1,924 results on '"RADIOSURGERY"'
Search Results
2. Incidental craniovertebral junction schwannoma: Surgical or radiosurgical management?
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Giuseppe Emmanuele Umana, Maurizio Passanisi, Bipin Chaurasia, and Gianluca Scalia
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craniovertebral junction ,gamma‐knife ,radiosurgery ,schwannoma ,Medicine ,Medicine (General) ,R5-920 - Abstract
Key Clinical Message Craniovertebral junction (CVJ) schwannomas are rare tumors, showing direct involvement of the atlanto‐occipital and atlanto‐axial joints. Microsurgical removal is the standard of care to improve symptoms and local control, but stereotactic radiosurgery (SRS) is an option. Both, surgery, and SRS, may show risks of severe complications. A 41‐year‐old male was referred to our department after incidental finding of a right‐sided C1 tumor. A CT angiogram with 3D reconstructions showed the close relationship between the tumor and the right vertebral artery (VA). A post‐contrast enhancement MRI revealed the presence of an extradural mass, sited at the level of the CVJ, mainly at the level of the right articular mass of C1. After multidisciplinary assessment, involving the gamma‐knife and neurosurgical teams, we performed a microsurgical resection of the tumor. Histology confirmed the diagnosis of schwannoma. At 1 year follow‐up the patient is stable, with no recurrence of the tumor. CVJ schwannoma's current standard of care is surgical resection, but longitudinal studies are required, and should promoted promptly since the recent introduction of the new version of GKSRS that allow the treatment of CVJ's lesions.
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- 2023
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3. Long-Term Hearing Outcome For Vestibular Schwannomas After Microsurgery And Radiotherapy: A Systematic Review and Meta-Analysis.
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Daloiso A, Cazzador D, Concheri S, Tealdo G, and Zanoletti E
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Objective: Hearing loss is a common symptom associated with vestibular schwannoma (VS), either because of the tumor's effects on the cochlear nerve or due to active treatments such as surgery or stereotactic radiosurgery (SRS). Treatment decisions for VS are based on factors including tumor size, hearing status, patient symptoms, and institutional preference. The study aimed to investigate long-term auditory outcomes in VS patients undergoing active treatments with a hearing preservation intent., Data Sources: A systematic literature review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, searching Scopus, Pubmed, and Web of Science databases from inception to January 2024., Review Methods: Studies meeting inclusion criteria, including a minimum 5-year follow-up and assessment of pre- and posttreatment hearing outcomes, were included. Pooled prevalence estimates for serviceable hearing after SRS and microsurgery were calculated using MetaXL software. Risk of bias assessment was performed with the Risk of Bias in Non-randomized Studies of Interventions tool., Results: Nine studies met the inclusion criteria, with 356 patients included for analysis. The pooled prevalence of maintaining serviceable hearing after SRS at 10 years was 18.1% (95% confidence interval [CI]: 1.7%-43.3%), with wide prediction intervals indicating variability in outcomes. Microsurgery demonstrated a higher prevalence of maintaining long-term serviceable hearing, with a pooled estimate of 74.5% (95% CI: 63.5%-84.1%)., Conclusion: This systematic review underscores the importance of long-term follow-up in evaluating auditory outcomes in VS treatment. Despite the biases inherent to pretreatment patients selection, hearing preservation microsurgery for sporadic VS removal demonstrated favorable and stable long-term serviceable hearing., (© 2024 The Author(s). Otolaryngology–Head and Neck Surgery published by Wiley Periodicals LLC on behalf of American Academy of Otolaryngology–Head and Neck Surgery Foundation.)
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- 2024
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4. The biological underpinnings of radiation therapy for vestibular schwannomas: Review of the literature
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Mark C. Dougherty, Seiji B. Shibata, and Marlan R. Hansen
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radiation therapy ,radiobiology ,radiosurgery ,vestibular schwannoma ,Otorhinolaryngology ,RF1-547 ,Surgery ,RD1-811 - Abstract
Abstract Objective Radiation therapy is a mainstay in the treatment of numerous neoplasms. Numerous publications have reported good clinical outcomes for primary radiation therapy for Vestibular Schwannomas (VS). However, there are relatively few pathologic specimens of VSs available to evaluate post‐radiation, which has led to a relative dearth in research on the cellular mechanisms underlying the effects of radiation therapy on VSs. Methods Here we review the latest literature on the complex biological effects of radiation therapy on these benign tumors—including resistance to oxidative stress, mechanisms of DNA damage repair, alterations in normal growth factor pathways, changes in surrounding vasculature, and alterations in immune responses following radiation. Results Although VSs are highly radioresistant, radiotherapy is often successful in arresting their growth. Conclusion By better understanding the mechanisms underlying these effects, we could potentially harness such mechanisms in the future to potentiate the clinical effects of radiotherapy on VSs. Level of Evidence N/A.
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- 2021
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5. Timing of fluorodeoxyglucose positron emission tomography maximum standardized uptake value for diagnosis of local recurrence of non‐small cell lung cancer after stereotactic body radiation therapy
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Daren Tan, Suki Gill, and Nelson Loh
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CT PET ,FDG‐PET ,NSCLC ,radiosurgery ,standardized uptake value ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Introduction After treatment with stereotactic body radiation therapy (SBRT), local recurrence of non‐small cell cancer (NSCLC) can be difficult to differentiate from radiation‐induced changes. Maximum standardized uptake value (SUVmax), measured with 18‐F‐Fluorodeoxyglucose positron emission tomography (FDG‐PET), can have false positives due to acute radiation inflammation. The primary study objective was to determine the utility of SUVmax > 5 to identify local recurrence later than 9 months after SBRT. Method A retrospective review was performed of FDG‐PET scans for suspicious CT findings after SBRT treatment of stage 1 NSCLC. SUVmax was measured including surrounding opacification. Outcome measures were local recurrence, progression free survival, and overall survival. Receiver operator curve analysis, sensitivity, specificity, and Kaplan‐Meier analysis were performed. Results Of 118 patients treated, 42 patients had eligible FDG‐PET scans. They received SBRT (48‐60Gy in 3‐8 fractions) for 49 NSCLC and had 101 follow‐up PET scans. The median time to first PET scan was 9.3 months, and the median follow‐up period was 22.4 months. Local recurrence was diagnosed in 12 patients, at a median of 16 months. Due to selection bias, the included patients had poorer outcomes than the entire cohort, with progression free survival (PFS) at 1, 2, and 3 years of 82.7%, 57.8%, and 45.8%; and overall survival of 97.9%, 79.9%, and 59.1%, respectively. Thirty FDG‐PET scans were performed within 9 months, of which 17% were false positives. A total of 71 FDG‐PET scans were performed beyond 9 months, and the median SUVmax was significantly higher for patients with local recurrence (7.48 vs. 2.14, P 5 has a sensitivity of 91% (95% CI 62%‐99.8%) and 100% (89.1%‐100%). Conclusion For local recurrence of NSCLC, SUVmax > 5 on FDG‐PET scan has good sensitivity and specificity after 6 months, but is highest beyond 9 months after SBRT.
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- 2020
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6. Low‐dose hilar and mediastinal stereotactic body radiation therapy for non‐small cell lung cancer: Analysis of outcomes in patients receiving one or multiple courses of treatment
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Roman O. Kowalchuk, Michael R. Waters, Martin Richardson, Kelly Spencer, James M. Larner, and Charles R. Kersh
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Carcinoma, non‐small cell lung ,dose fractionation, radiation ,lung neoplasms ,patient selection ,radiosurgery ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Background This study reports the outcomes of a single institutional experience treating non‐small cell lung cancer (NSCLC) involving the pulmonary hilum with low‐dose stereotactic body radiation therapy (SBRT). The authors also present a series of repeat hilar SBRT. Methods Inclusion criteria required treatment with SBRT for NSCLC involving regional lymph nodes of the: (i) hilum, (ii) mediastinum, (iii) aortopulmonary window (station 5), or (iv) mainstem bronchus. At least one clinical follow‐up with imaging was required, unless the patient had a prior documented death from cancer. Results A total of 32 patients with 44 treatments were included, and 37 treatments targeted the hilum directly, with seven concerning the mediastinum, AP window, or mainstem bronchus. Median dose was 28 Gy in four fractions with once‐weekly fractionation. At a median clinical follow‐up of 23 months, local control was 64%. Median overall survival was 24 months, and median progression‐free survival was 15 months. A total of 48% of treatments resulted in complete radiographic response on last imaging follow‐up, and no cases of grade ≥ 3 toxicity were reported. For repeat SBRT (after prior hilar SBRT), local control was 92%. Median overall survival was 20 months, and median progression‐free survival was 19 months. Complete radiographic response was noted after 58% of treatments, with 0 instances of progressive response and no reported side effects. Conclusions Low‐dose hilar SBRT was efficacious and well‐tolerated, with impressive overall survival and no grade ≥ 3 toxicity. Repeat treatments with SBRT were feasible and effective, demonstrating overall survival, local control, and toxicity comparable to primary treatments. Key points Significant findings of the study Low‐dose hilar SBRT was efficacious and well‐tolerated Repeated treatments with SBRT demonstrated encouraging results, comparable to primary treatments What this study adds This study contributes to the small body of literature concerning hilar SBRT Repeat hilar SBRT was safe and feasible Toxicity was minimal with low‐dose SBRT Once‐weekly fractionation may have contributed to low rate of side effects.
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- 2020
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7. Epileptic encephalopathies secondary to hypothalamic hamartomas treated with radiosurgery: A case series.
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Jaramillo-Jiménez E, Sandoval-Barrios J, Walsh FJ, Jaramillo-Jiménez MC, Echeverri-Sánchez JD, Rodríguez-Márquez IA, Barrientos-Montoya HD, Ascencio-Lancheros JL, Giraldo-Palacio JF, Sierra-Arrieta IM, Gómez-Duque DI, Pérez-López S, and Bustamante MT
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Objective: Hypothalamic hamartomas are congenital lesions that typically present with gelastic seizures, refractory epilepsy, neurodevelopmental delay, and severe cognitive impairment. Surgical procedures have been reported to be effective in removing the hamartomas, however, they are associated with significant morbidity. Therefore, it is not considered a safe therapeutic modality. Image-guided robotic radiosurgery (CyberKnife® Radiosurgery System) has been shown to provide good outcomes without lasting complications., Methods: This series of cases describes the clinical, radiological, radiotherapeutic, and postsurgical outcomes of five patients with epileptic encephalopathies secondary to hypothalamic hamartomas who were treated with CyberKnife®., Results: All patients exhibited refractory epilepsy with gelastic seizures and were unsuitable candidates for surgical resection The prescribed dose ranged between 16 and 25 Gy, delivered in a single fraction for four patients and five fractions for one patient while adhering strictly to visual pathway constraints. After radiosurgery, four patients maintained seizure control (one with an Engel class Ia, three with an Engel class 1d), and another presented sporadic, nondisabling gelastic seizures (with an Engel class IIa). After 24-26 months of follow-up, in three patients, their intelligence quotient scores increased. No complications were reported., Significance: This report suggests that Cyberknife may be a good option for treating hypothalamic hamartoma, particularly in cases where other noninvasive alternatives are unavailable. Nevertheless, additional studies are essential in order to evaluate the effectiveness of the technique in these cases., (© 2024 International League Against Epilepsy.)
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- 2024
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8. Evaluation of inverse treatment planning for gamma knife radiosurgery using fMRI brain activation maps as organs at risk
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Background: Stereotactic radiosurgery (SRS) can be an effective primary or adjuvant treatment option for intracranial tumors. However, it carries risks of various radiation toxicities, which can lead to functional deficits for the patients. Current inverse planning algorithms for SRS provide an efficient way for sparing organs at risk (OARs) by setting maximum radiation dose constraints in the treatment planning process.Purpose: We propose using activation maps from functional MRI (fMRI) to map the eloquent regions of the brain and define functional OARs (fOARs) for Gamma Knife SRS treatment planning.Methods: We implemented a pipeline for analyzing patient fMRI data, generating fOARs from the resulting activation maps, and loading them onto the GammaPlan treatment planning software. We used the Lightning inverse planner to generate multiple treatment plans from open MRI data of five subjects, and evaluated the effects of incorporating the proposed fOARs.Results: The Lightning optimizer designs treatment plans with high conformity to the specified parameters. Setting maximum dose constraints on fOARs successfully limits the radiation dose incident on them, but can have a negative impact on treatment plan quality metrics. By masking out fOAR voxels surrounding the tumor target it is possible to achieve high quality treatment plans while controlling the radiation dose on fOARs.Conclusions: The proposed method can effectively reduce the radiation dose incident on the eloquent brain areas during Gamma Knife SRS of brain tumors., Funding: Centrum foer Industriell Informationsteknologi, Linkoepings Universitet; Vinnova [2018-02230, 2021-01954]
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- 2023
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9. Evaluation of inverse treatment planning for gamma knife radiosurgery using fMRI brain activation maps as organs at risk
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Background: Stereotactic radiosurgery (SRS) can be an effective primary or adjuvant treatment option for intracranial tumors. However, it carries risks of various radiation toxicities, which can lead to functional deficits for the patients. Current inverse planning algorithms for SRS provide an efficient way for sparing organs at risk (OARs) by setting maximum radiation dose constraints in the treatment planning process.Purpose: We propose using activation maps from functional MRI (fMRI) to map the eloquent regions of the brain and define functional OARs (fOARs) for Gamma Knife SRS treatment planning.Methods: We implemented a pipeline for analyzing patient fMRI data, generating fOARs from the resulting activation maps, and loading them onto the GammaPlan treatment planning software. We used the Lightning inverse planner to generate multiple treatment plans from open MRI data of five subjects, and evaluated the effects of incorporating the proposed fOARs.Results: The Lightning optimizer designs treatment plans with high conformity to the specified parameters. Setting maximum dose constraints on fOARs successfully limits the radiation dose incident on them, but can have a negative impact on treatment plan quality metrics. By masking out fOAR voxels surrounding the tumor target it is possible to achieve high quality treatment plans while controlling the radiation dose on fOARs.Conclusions: The proposed method can effectively reduce the radiation dose incident on the eloquent brain areas during Gamma Knife SRS of brain tumors., Funding: Centrum foer Industriell Informationsteknologi, Linkoepings Universitet; Vinnova [2018-02230, 2021-01954]
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- 2023
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10. Evaluation of inverse treatment planning for gamma knife radiosurgery using fMRI brain activation maps as organs at risk
- Abstract
Background: Stereotactic radiosurgery (SRS) can be an effective primary or adjuvant treatment option for intracranial tumors. However, it carries risks of various radiation toxicities, which can lead to functional deficits for the patients. Current inverse planning algorithms for SRS provide an efficient way for sparing organs at risk (OARs) by setting maximum radiation dose constraints in the treatment planning process.Purpose: We propose using activation maps from functional MRI (fMRI) to map the eloquent regions of the brain and define functional OARs (fOARs) for Gamma Knife SRS treatment planning.Methods: We implemented a pipeline for analyzing patient fMRI data, generating fOARs from the resulting activation maps, and loading them onto the GammaPlan treatment planning software. We used the Lightning inverse planner to generate multiple treatment plans from open MRI data of five subjects, and evaluated the effects of incorporating the proposed fOARs.Results: The Lightning optimizer designs treatment plans with high conformity to the specified parameters. Setting maximum dose constraints on fOARs successfully limits the radiation dose incident on them, but can have a negative impact on treatment plan quality metrics. By masking out fOAR voxels surrounding the tumor target it is possible to achieve high quality treatment plans while controlling the radiation dose on fOARs.Conclusions: The proposed method can effectively reduce the radiation dose incident on the eloquent brain areas during Gamma Knife SRS of brain tumors., Funding: Centrum foer Industriell Informationsteknologi, Linkoepings Universitet; Vinnova [2018-02230, 2021-01954]
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- 2023
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11. Long-term outcomes of Gamma Knife radiosurgery in treating glossopharyngeal neuralgia.
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Samanci Y, Mürdün E, Çil M, Düzkalir AH, Askeroglu MO, and Peker S
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- Humans, Middle Aged, Follow-Up Studies, Retrospective Studies, Treatment Outcome, Pain etiology, Radiosurgery adverse effects, Radiosurgery methods, Glossopharyngeal Nerve Diseases surgery, Glossopharyngeal Nerve Diseases etiology, Trigeminal Neuralgia etiology
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Glossopharyngeal neuralgia (GPN) is an unusual disorder causing severe, brief pain episodes in the areas supplied by the glossopharyngeal nerve. Initial treatment involves medications like carbamazepine, but if these are ineffective or cause side effects, interventional pain management techniques or surgery may be considered. Gamma Knife radiosurgery is becoming popular in managing GPN due to its lower risk of complications than surgical interventions like microvascular decompression or rhizotomy. In this retrospective case series, we examined the outcomes of Gamma Knife radiosurgery in eight patients with GPN. The decision to utilize Gamma Knife radiosurgery was made following specific criteria, including failed surgical interventions, patient preference against surgery, or contraindications to surgical procedures. Patients were administered radiation doses within the range of 80 to 90 Gy, targeting either the cisternal glossopharyngeal nerve or glossopharyngeal meatus of the jugular foramen. Evaluations were conducted before the Gamma Knife radiosurgery; at 3, 6, and 12 months after Gamma Knife radiosurgery; and annually thereafter. Pain severity was assessed using the modified Barrow Neurological Institute scale grades, with patients achieving grade I-IIIa considered to have a good treatment outcome and grade IV-V to have a poor treatment outcome. Pain control and absence of radiosurgery-related complications were primary endpoints. The median age of the patients was 46.5 years, varying from 8 to 72 years. The median duration of pain was 32 months (range, 12-120 months). All patients, except one, were on polydrug therapy. All cases exhibited preoperative grade V pain. The median follow-up duration after Gamma Knife radiosurgery was 54.5 months, varying from 14 to 90 months. The overall clinical assessments revealed a gradual neurological improvement, particularly within the first 8.5 weeks (range, 1-12 weeks). The immediate outcomes at 3 months revealed that all patients (8/8, 100%) experienced pain relief, with 25% (2/8) achieving a medication-free status (Grade I). Three patients (37%) experienced a recurrence during the follow-up and were managed with repeat Gamma Knife radiosurgery (n = 2) and radiofrequency rhizotomy (n = 1). At the last follow-up, 88% (7/8) of patients had pain relief (Grades I-IIIa), with three (37%) achieving a medication-free status (Grade I). No adverse events or neurological complications occurred. The patient who underwent radiofrequency rhizotomy continued to experience inadequately controlled pain despite medication (Grade IV). Gamma Knife radiosurgery is a non-invasive, efficacious treatment option for idiopathic GPN, offering short- and long-term relief without permanent complications., (© 2024 American Headache Society.)
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- 2024
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12. Hypothalamic hamartomas in adulthood: Clinical spectrum and treatment outcome—A unicenter experience
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Estefanía Conde Blanco, Carla Anciones Martín, Isabel Manzanares, Francisco Gil López, Pedro Roldán, Antonio Donaire, Jordi Rumiá, and Mar Carreño
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adult ,epilepsy ,hypothalamic hamartoma ,radiosurgery ,seizures ,treatment ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Abstract Introduction Clinical manifestations of the hypothalamic hamartoma‐epilepsy syndrome (HH‐ES) in adulthood are variable. Efficacy of therapeutic options and outcome are diverse. Methods Retrospective study of adult patients diagnosed with a HH in magnetic resonance imaging and epilepsy who attended our tertiary Epilepsy Unit between 2003 and 2018. We report the clinical and electroencephalographic features of a series of adult patients with HH and related epilepsy seen in our center together with the treatments and seizure outcome. Results We describe a series of eight patients. Five males (62.5%), median age at evaluation was 28.5 years (IQR: 15.5). Clinical manifestations included focal with preserved and impaired awareness emotional seizures (gelastic seizures [GS]) in six patients (75%), focal tonic, atonic with impaired awareness and focal to bilateral tonic–clonic seizures. Mild GS were the only symptom in one patient. Three patients (37.5%) had endocrinological disturbances such as obesity and hypothyroidism. Fifty percent of the patients showed psychiatric comorbidity such as anxiety disorder and aggressiveness, and two patients had psychomotor delay. Seven patients (87.7%) had drug‐resistant seizures and three of them were treated with radiosurgery. Out of the treated group, only one (33.3%) became seizure‐free 2 years after surgery but developed psychiatric problems. The other two patients had an Engel IV outcome and received a vagal nerve stimulation (VNS) implant. VNS did not lead to changes either in intensity nor in seizure frequency. Conclusions Hypothalamic hamartoma‐epilepsy syndrome clinical manifestations in adult patients are as variable as at pediatric age. Outcome of therapeutic options such as radiosurgery or VNS may be poorer at this stage.
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- 2019
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13. Risk‐adapted stereotactic body radiotherapy for patients with cervical spinal metastases
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Huan‐Huan Wang, Shou‐Sen Tian, Jia‐Min Yang, Bing‐Sheng Sun, Ying Chen, Yong‐Chun Song, Yang Dong, Jing‐Sheng Wang, Zhi‐Yong Yuan, Yao‐Li Cui, and Mao‐Bin Meng
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Cancer Research ,Spinal Neoplasms ,Oncology ,Fractures, Compression ,Carcinoma ,Humans ,Spinal Fractures ,Pain ,General Medicine ,Radiosurgery - Abstract
Owing to the complex anatomical structure and biomechanics, the current standard palliative treatments for cervical spinal metastases are associated with a high risk of recurrence and complications. Stereotactic body radiotherapy (SBRT) can provide radical dose to tumors while protecting normal organs to the maximum extent. However, the efficacy and safety of SBRT for cervical spinal metastases is not well characterized. Data from 71 patients with cervical spine metastases who were treated with SBRT using CyberKnife between 2006 and 2021 were obtained from our prospectively maintained database. Primary endpoint was pain response at 12 weeks following SBRT completion; secondary endpoints included local control (LC), overall survival (OS), and adverse events. Standard-risk patients were planned to receive 30 Gy (range 21-36) with median fractions of 3 (range 1-3) and high-risk patients 35 Gy (range 24-50) with median fractions of 5 (range 4-5) according to the spinal cord and esophagus dose constraints. The median follow-up time was 17.07 months (range 3.1-118.9). After 12 weeks of SBRT completion, 54 (98.2%) of 55 patients with baseline pain achieved pain response and 46 (83.6%) achieved complete pain response. LC rates were 93.1% and 90% at 1 year and 2 year, respectively. The 1-year and 2-year OS rates were 66.2% and 37.4%, respectively. Eight patients experienced grades 1-4 adverse events (six vertebral compression fracture [VCF], five of them had VCF before SBRT; and two hemiparesis). No grade 5 adverse events were observed. Therefore, risk-adapted SBRT for cervical spine metastases achieved high pain control and LC rates with acceptable adverse events.
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- 2022
14. Technical note: Absolute dose measurements of a vault‐free radiosurgery system
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Stephen P, Sorensen, Shyam S, Jani, Dilini S, Pinnaduwage, Xiangsheng, Yan, and Shiv P, Srivastava
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Phenylpropionates ,Phantoms, Imaging ,Calibration ,Water ,General Medicine ,Radiosurgery ,Radiometry - Abstract
Methods for accurate absolute dose (AD) calibration are essential for the proper functioning of radiotherapy treatment machines. Many systems do not conform to TG-51 calibration standards, and modifications are required. TG-21 calibration is also a viable methodology for these situations with the appropriate setup, equipment, and factors. It has been shown that both these methods result in minimal errors. A similar approach has been taken in calibrating the dose for a recent vault-free radiosurgery system.To evaluate modified TG-21 and TG-51 protocols for AD calibrations of the ZAP-X radiosurgery system using ion chambers, film, and thermoluminescent dosimeters (TLDs).The current treatment planning system for ZAP-X requires AD calibration at dMeasurements from TG-51, TG-21 (utilizing the custom acrylic phantom), film, and TLDs agreed to within ± 2%.A modified TG-51 AD calculation in water is preferred but may not be practical due to the difficulty in tank setup. The TG-21 modified protocol using a custom acrylic phantom is an accurate alternative option for dose calibration. Both of these methods are within acceptable agreement and provide confidence in the system's AD calibration.
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- 2022
15. Low‐rank fusion convolutional neural network for prediction of remission after stereotactic radiosurgery in patients with acromegaly: a proof‐of‐concept study
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Nidan Qiao, Damin Yu, Guoqing Wu, Qilin Zhang, Boyuan Yao, Min He, Hongying Ye, Zhaoyun Zhang, Yongfei Wang, Hanfeng Wu, Yao Zhao, and Jinhua Yu
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Treatment Outcome ,Artificial Intelligence ,Acromegaly ,Humans ,Neural Networks, Computer ,Radiosurgery ,Follow-Up Studies ,Retrospective Studies ,Pathology and Forensic Medicine - Abstract
Artificial intelligence approaches to analyze pathological images (pathomic) for outcome prediction have not been sufficiently considered in the field of pituitary research. A total of 5,504 hematoxylineosin-stained pathology image tiles from 58 acromegalic patients with a good or poor outcome were integrated with other clinical and genetic information to train a low-rank fusion convolutional neural network (LFCNN). The model was externally validated in 1,536 patches from an external cohort. The primary outcome was the time to the first endocrine remission after stereotactic radiosurgery (SRS). The median time of initial endocrine remission was 43 months (interquartile range [IQR]: 13-60 months) after SRS, and the 24-month initial cumulative remission rate was 57.9% (IQR: 46.4-72.3%). The patient-wise accuracy of the LFCNN model in predicting the primary outcome was 92.9% in the internal test dataset, and the sensitivity and specificity were 87.5 and 100.0%, respectively. The LFCNN model was a strong predictor of initial cumulative remission in the training cohort (hazard ratio [HR] 9.58, 95% confidence interval [CI] 3.89-23.59; p 0.001) and was higher than that of established prognostic markers. The predictive value of the LFCNN model was further validated in an external cohort (HR 9.06, 95% CI 1.14-72.25; p = 0.012). In this proof-of-concept study, clinically and genetically useful prognostic markers were integrated with digital images to predict endocrine outcomes after SRS in patients with active acromegaly. The model considerably outperformed established prognostic markers and can potentially be used by clinicians to improve decision-making regarding adjuvant treatment choices. © 2022 The Pathological Society of Great Britain and Ireland.
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- 2022
16. Gamma knife radiosurgery for patients with brain metastases from non–small cell lung cancer: Comparison of survival between <5 and ≥5 metastases
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Xu Zhao, Shouluan Ding, Ming Zhang, and Chengwei Wang
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Pulmonary and Respiratory Medicine ,Lung Neoplasms ,Oncology ,Brain Neoplasms ,Carcinoma, Non-Small-Cell Lung ,Humans ,General Medicine ,Radiosurgery ,Retrospective Studies - Abstract
Current evidence-based guidelines support stereotactic radiosurgery (SRS) for patients with up to four brain metastases (BMs). However, debate continues about how many tumors may be treated by SRS alone.This retrospective study included non-small cell lung cancer (NSCLC) patients with BMs treated with gamma knife as the initial treatment for cerebral lesions. The patients were followed up to obtain their survival information. The outcomes were statistically analyzed to compare the differences in survival between the5 BMs and ≥5 BMs groups and to identify prognostic factors.A total of 77 patients were divided into two groups (54 patients with5 BMs and 23 patients with ≥5 BMs). The median overall survival (OS) was 18.3 months in the5 BMs group and 17.7 months in the ≥5 BMs group. The median intracranial progression-free survival (IPFS) was 9.0 months in the5 BMs group and 9.9 months in the ≥5 BMs group. There was no significant difference in OS and IPFS between the two groups. The multivariate analysis demonstrated that adenocarcinoma, controlled primary cancer, higher Karnofsky Performance Scale (KPS), and salvage treatment were independent prognostic factors favoring longer OS.SRS alone as the initial treatment for NSCLC patients with more than four BMs was non-inferior to SRS for those with one to four BMs in terms of OS and IPFS.
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- 2022
17. Cost of cardiac stereotactic body radioablation therapy versus catheter ablation for treatment of ventricular tachycardia
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Chen Wei, Michelle Boeck, Pierre C. Qian, Todd Vivenzio, Zoe Elizee, Jeremy S. Bredfeldt, Robert S. Kaplan, Usha Tedrow, Raymond Mak, and Paul C. Zei
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Treatment Outcome ,Catheter Ablation ,Tachycardia, Ventricular ,Humans ,General Medicine ,Radiosurgery ,Cardiology and Cardiovascular Medicine ,Anti-Arrhythmia Agents ,Retrospective Studies - Abstract
To compare the cost of cardiac stereotactic body radioablation therapy (SBRT) versus catheter ablation for treating ventricular tachycardia (VT).Cardiac SBRT is a novel way of treating refractory VT that may be less costly than catheter ablation, owing to its noninvasive, outpatient nature. However, the true costs of either procedure are not well described, which could help inform a more appropriate reimbursement for cardiac SBRT than simply cross-indexing existing procedural rates.Process maps were derived for the full patient care cycle of both procedures using time-driven activity-based costing. Step-by-step timestamps were collected prospectively from a 10-patient SBRT cohort and retrospectively from a 59-patient catheter ablation cohort. Individual costs were estimated by multiplying timestamps with capacity cost rates (CCRs) for personnel, space, equipment, consumable, and indirect resources. These were summed into total cost, which for cardiac SBRT was compared with current catheter ablation and single-fraction lung SBRT reimbursements, both potential reference rates for cardiac SBRT.The direct and total procedural costs of cardiac SBRT ($7549 and $10,621) were 49% and 54% less than those of VT ablation ($14,707 and $23,225). These costs were significantly different from current reimbursement for catheter ablation ($22,692) and lung SBRT ($6329). After including hospitalization expenses (≥$15,000), VT ablation costs at least $27,604 more to furnish than cardiac SBRT.Time-driven activity-based costing (TDABC) can be a helpful tool for assessing healthcare costs, including novel treatment approaches. In addition to its clinical benefits, cardiac SBRT may provide significant cost reduction opportunities for treatment of VT.
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- 2022
18. Volumetric reduction of brain metastases after stereotactic radiotherapy: Prognostic factors and effect on local control
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Naoyuki Kanayama, Toshiki Ikawa, Shingo Ohira, Takero Hirata, Masahiro Morimoto, Kazuhiko Ogawa, Teruki Teshima, and Koji Konishi
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Cancer Research ,Oncology ,Brain Neoplasms ,Multivariate Analysis ,Humans ,Radiotherapy Dosage ,Radiology, Nuclear Medicine and imaging ,Prognosis ,Radiosurgery ,Proportional Hazards Models ,Retrospective Studies - Abstract
Few reports include volumetric measurements as endpoints after stereotactic radiotherapy (SRT) despite the importance of such measurements. This study aimed to (1) investigate the impact of the volumetric response (specifically, an over 65% and over 90% volume reduction in brain metastases) at 6 months post-SRT on local control and (2) identify the predictive factors for a volumetric response of over 65% and over 90%.This study included 250 unresected brain metastases (0.3 cc) treated with SRT. Doses were stratified according to the biological effective dose (BED). The BED was calculated using four models: linear-quadratic (LQ): α/β = 10; LQ: α/β = 20; LQ cubic: α/β = 12; and LQ linear: α/β = 10. The median prescription dose was 30 Gy/3 fractions (BED20, 45). The median follow-up time after SRT was 18.6 months (range, 6.4-81.8 months).In the multivariate analysis, over 65% volume reduction and over 90% volume reduction were prognostic factors for local control (hazard ratio: 2.370, p = 0.011 and hazard ratio: 3.161, p = 0.014, respectively). A dose of 80% of the gross tumor volume (GTV) D80 BED20 58 was a predictive factor for over 65% and over 90% volume reductions (odds ratio: 1.975, p = 0.023; odds ratio: 3.204, p 0.001, respectively).Robust volume reduction of brain metastases at 6 months post-SRT can predict local control. GTV D80 in the LQ model: α/β = 20 may be warranted for good volume reduction.
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- 2022
19. Demonstrating the benefits of corrective intraoperative feedback in improving the quality of duodenal hydrogel spacer placement
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Hamed Hooshangnejad, Sarah Han‐Oh, Eun Ji Shin, Amol Narang, Avani Dholakia Rao, Junghoon Lee, Todd McNutt, Chen Hu, John Wong, and Kai Ding
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Organs at Risk ,Duodenum ,Radiotherapy Planning, Computer-Assisted ,Cadaver ,Humans ,Hydrogels ,Radiotherapy Dosage ,General Medicine ,Radiosurgery ,Feedback - Abstract
Pancreatic cancer is the fourth leading cause of cancer-related death with a 10% 5-year overall survival rate (OS). Radiation therapy (RT) in addition to dose escalation improves the outcome by significantly increasing the OS at 2 and 3 years but is hindered by the toxicity of the duodenum. Our group showed that the insertion of hydrogel spacer reduces duodenal toxicity, but the complex anatomy and the demanding procedure make the benefits highly uncertain. Here, we investigated the feasibility of augmenting the workflow with intraoperative feedback to reduce the adverse effects of the uncertainties.We simulated three scenarios of the virtual spacer for four cadavers with two types of gross tumor volume (GTV) (small and large); first, the ideal injection; second, the nonideal injection that incorporates common spacer placement uncertainties; and third, the corrective injection that uses the simulation result from nonideal injection and is designed to compensate for the effect of uncertainties. We considered two common uncertainties: (1) "Narrowing" is defined as the injection of smaller spacer volume than planned. (2) "Missing part" is defined as failure to inject spacer in the ascending section of the duodenum. A total of 32 stereotactic body radiation therapy (SBRT) plans (33 Gy in 5 fractions) were designed, for four cadavers, two GTV sizes, and two types of uncertainties. The preinjection scenario for each case was compared with three scenarios of virtual spacer placement from the dosimetric and geometric points of view.We found that the overlapping PTV space with the duodenum is an informative quantity for determining the effective location of the spacer. The ideal spacer distribution reduced the duodenal V33Gy for small and large GTV to less than 0.3 and 0.1cc, from an average of 3.3cc, and 1.2cc for the preinjection scenario. However, spacer placement uncertainties reduced the efficacy of the spacer in sparing the duodenum (duodenal V33Gy: 1.3 and 0.4cc). The separation between duodenum and GTV decreased by an average of 5.3 and 4.6 mm. The corrective feedback can effectively bring back the expected benefits from the ideal location of the spacer (averaged V33Gy of 0.4 and 0.1cc).An informative feedback metric was introduced and used to mitigate the effect of spacer placement uncertainties and maximize the benefits of the EUS-guided procedure.
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- 2022
20. A volume‐independent conformity index for stereotactic radiosurgery
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Seungjong, Oh, Musaddiq J, Awan, James I, Monroe, Yun, Liang, Rodney E, Wegner, Stephen, Karlovits, Mitchell, Machtay, Simon S, Lo, Andrew, Sloan, and Jason W, Sohn
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Brain Neoplasms ,Radiotherapy Planning, Computer-Assisted ,Humans ,Radiotherapy Dosage ,General Medicine ,Radiosurgery ,Tumor Burden - Abstract
To develop a volume-independent conformity metric called the Gaussian Weighted Conformity Index (GWCI) to evaluate stereotactic radiosurgery/radiotherapy (SRS/SRT) plans for small brain tumors.A signed bi-directional local distance (BLD) between the prescription isodose line and the target contour is determined for each point along the tumor contour (positive distance represents under-coverage). A similarity score function (SF) is derived from Gaussian function, penalizing under- and over-coverage at each point by assigning standard deviations of the Gaussian function. Each point along the dose line contour is scored with this SF. The average of the similarity scores determines the GWCI. A total of 40 targets from 18 patients who received Gamma-Knife SRS/SRT treatments were analyzed to determine appropriate penalty criteria. The resulting GWCIs for test cases already deemed clinically acceptable are presented and compared to the same cases scored with the New Conformity Index to determine the influence of tumor volumes on the two conformity indices (CIs).A total of four penalty combinations were tested based on the signed BLDs from the 40 targets. A GWCI of 0.9 is proposed as a cutoff for plan acceptability. The GWCI exhibits no target volume dependency as designed.A limitation of current CIs, volume dependency, becomes apparent when applied to SRS/SRT plans. The GWCI appears to be a more robust index, which penalizes over- and under-coverage of tumors and is not skewed by the tumor volume.
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- 2022
21. A PI3K gene expression signature predicts for recurrence in early-stage non-small cell lung cancer treated with stereotactic body radiation therapy.
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Sebastian NT, Webb A, Shilo K, Robb R, Xu-Welliver M, Haglund K, Brownstein J, DeNicola GM, Shen C, and Williams TM
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- Humans, Neoplasm Staging, Phosphatidylinositol 3-Kinases genetics, Retrospective Studies, Transcriptome, Treatment Outcome, Carcinoma, Non-Small-Cell Lung genetics, Carcinoma, Non-Small-Cell Lung radiotherapy, Lung Neoplasms genetics, Lung Neoplasms radiotherapy, Radiosurgery, Small Cell Lung Carcinoma pathology
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Introduction: Increasingly, early-stage non-small cell lung cancer (NSCLC) is treated with stereotactic body radiation therapy (SBRT). Although treatment is generally effective, a small subset of tumors will recur because of radioresistance. Preclinical studies suggested PI3K-AKT-mTOR activation mediates radioresistance. This study sought to validate this finding in tumor samples from patients who underwent SBRT for NSCLC., Methods: Patients with T1-3N0 NSCLC treated with SBRT at our institution were included. Total RNA of formalin-fixed paraffin-embedded tumor biopsy specimens (pretherapy) was isolated and analyzed using the Clariom D assay. Risk scores from a PI3K activity signature and four published NSCLC signatures were generated and dichotomized by the median. Kaplan-Meier curves and Cox regressions were used to analyze their association with recurrence and overall survival (OS). The PI3K signature was also tested in a data set of resected NSCLC for additional validation., Results: A total of 92 patients were included, with a median follow-up of 18.3 months for living patients. There was no association of any of the four published gene expression signatures with recurrence or OS. However, high PI3K risk score was associated with higher local recurrence (hazard ratio [HR], 11.72; 95% CI, 1.40-98.0; p = .023) and worse disease-free survival (DFS) (HR, 3.98; 95% CI, 1.57-10.09; p = .0035), but not OS (p = .49), regional recurrence (p = .15), or distant recurrence (p = .85). In the resected NSCLC data set (n = 361), high PI3K risk score was associated with decreased OS (log-rank p = .013) but not DFS (p = 0.54)., Conclusions: This study validates that higher PI3K activity, measured by gene expression, is associated with local recurrence and worse DFS in early-stage NSCLC patients treated with SBRT. This may be useful in prognostication and/or tailoring treatment, and merits further validation., (© 2023 The Authors. Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.)
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- 2023
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22. Immunotherapy plus stereotactic radiation therapy improves event-free survival in early-stage non-small cell lung cancer.
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- Humans, Progression-Free Survival, Immunotherapy, Treatment Outcome, Neoplasm Staging, Carcinoma, Non-Small-Cell Lung radiotherapy, Lung Neoplasms radiotherapy, Radiosurgery, Small Cell Lung Carcinoma
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- 2023
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23. OptImal Gamma kNife lIghTnIng sOlutioN (IGNITION) score to characterize the solution space of the Gamma Knife FIP optimizer for stereotactic radiosurgery
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Ranjini Tolakanahalli, D Jay J. Wieczorek, Yongsook C. Lee, Martin C. Tom, Matthew D. Hall, Michael W. McDermott, Minesh P. Mehta, Rupesh Kotecha, and Alonso N. Gutierrez
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inverse optimizer ,Radiation ,Brain Neoplasms ,Gamma Knife ,Radiotherapy Planning ,stereotactic radiosurgery ,Clinical Sciences ,Medical Physiology ,Radiotherapy Dosage ,Radiosurgery ,Lightning ,Arteriovenous Malformations ,Other Physical Sciences ,Nuclear Medicine & Medical Imaging ,Computer-Assisted ,Humans ,Radiology, Nuclear Medicine and imaging ,Instrumentation ,Cancer - Abstract
ObjectivesThe objective of this study is to evaluate the user-defined optimization settings in the Fast Inverse Planning (FIP) optimizer in Leksell GammaPlan® and determine the parameters that result in the best stereotactic radiosurgery (SRS) plan quality for brain metastases, benign tumors, and arteriovenous malformations (AVMs).MethodsThirty patients with metastases and 30 with benign lesions-vestibular schwannoma, AVMs, pituitary adenoma, and meningioma-treated with SRS were evaluated. Each target was planned by varying the low dose (LD) and beam-on-time (BOT) penalties in increments of 0.1, from 0 to 1. The following plan quality metrics were recorded for each plan: Paddick conformity index (PCI), gradient index (GI), BOT, and maximum organ-at-risk (OAR) doses. A novel objective score matrix was calculated for each target using a linearly weighted combination of the aforementioned metrics. A histogram of optimal solutions containing the five best scores was extracted.ResultsA total of 7260 plans were analyzed with 121 plans per patient for the range of LD/BOT penalties. The ranges of PCI, GI, and BOT across all metastatic lesions were 0.58-0.97, 2.1-3.8, and 8.8-238 min, respectively, and were 0.13-0.97, 2.1-3.8, and 8.8-238 min, respectively, for benign lesions. The objective score matrix showed unique optimal solutions for metastatic lesions and benign lesions. Additionally, the plan metrics of the optimal solutions were significantly improved compared to the clinical plans for metastatic lesions with equivalent metrics for all other cases.ConclusionIn this study, FIP optimizer was evaluated to determine the optimal solution space to maximize PCI and minimize GI, BOT and OAR doses simultaneously for single metastatic/benign/non-neoplastic targets. The optimal solution chart was determined using a novel objective score which provides novice and expert planners a roadmap to generate the most optimal plans efficiently using FIP.
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- 2023
24. Automatic inverse treatment planning of Gamma Knife radiosurgery via deep reinforcement learning
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Yingzi Liu, Chenyang Shen, Tonghe Wang, Jiahan Zhang, Xiaofeng Yang, Tian Liu, Shannon Kahn, Hui‐Kuo Shu, and Zhen Tian
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Radiotherapy Planning, Computer-Assisted ,Humans ,FOS: Physical sciences ,Radiotherapy Dosage ,Neuroma, Acoustic ,Medical Physics (physics.med-ph) ,General Medicine ,Radiosurgery ,Physics - Medical Physics ,Algorithms - Abstract
Several inverse planning algorithms have been developed for Gamma Knife (GK) radiosurgery to determine a large number of plan parameters by solving an optimization problem, which typically consists of multiple objectives. The priorities among these objectives need to be repetitively adjusted to achieve a clinically good plan for each patient. This study aimed to achieve automatic and intelligent priority tuning by developing a deep reinforcement learning (DRL)-based method to model the tuning behaviors of human planners.We built a priority-tuning policy network using deep convolutional neural networks. Its input was a vector composed of multiple plan metrics that were used in our institution for GK plan evaluation. The network can determine which tuning action to take based on the observed quality of the intermediate plan. We trained the network using an end-to-end DRL framework to approximate the optimal action-value function. A scoring function was designed to measure the plan quality to calculate the received reward of a tuning action.Vestibular schwannoma was chosen as the test bed in this study. The number of training, validation and testing cases were 5, 5, and 16, respectively. For these three datasets, the average scores of the initial plans obtained with the same initial priority set were 3.63 ± 1.34, 3.83 ± 0.86 and 4.20 ± 0.78, respectively, while they were improved to 5.28 ± 0.23, 4.97 ± 0.44 and 5.22 ± 0.26 through manual priority tuning by human expert planners. Our network achieved competitive results with 5.42 ± 0.11, 5.10 ± 0. 42, 5.28 ± 0.20, respectively.Our network can generate GK plans of comparable or slightly higher quality than the plans generated by human planners via manual priority tuning for vestibular schwannoma cases. The network can potentially be incorporated into the clinical workflow as planning assistance to improve GK planning efficiency and help to reduce plan quality variation caused by interplanner variability. We also hope that our method can reduce the workload of GK planners and allow them to spend more time on more challenging cases.
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- 2022
25. Stereotactic radiosurgery for melanoma brain metastases: Concurrent immune checkpoint inhibitor therapy associated with superior clinicoradiological response outcomes
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Mihir D Shanker, Sidyarth Garimall, Nick Gatt, Heath Foley, Samuel Crowley, Emma Le Cornu, Kendall Muscat, Wei Soon, Victoria Atkinson, Wen Xu, Trevor Watkins, Michael Huo, Matthew C Foote, and Mark B Pinkham
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Oncology ,Brain Neoplasms ,Humans ,Radiology, Nuclear Medicine and imaging ,Immunotherapy ,Radiosurgery ,Immune Checkpoint Inhibitors ,Melanoma ,Retrospective Studies - Abstract
This study assessed long-term clinical and radiological outcomes following treatment with combination stereotactic radiosurgery (SRS) and immunotherapy (IT) for melanoma brain metastases (BM).A retrospective review was performed in a contemporary cohort of patients with melanoma BM at a single tertiary institution receiving Gamma Knife101 patients (435 melanoma BM) were treated with SRS between January-2015 and June-2019. 68.3% of patients received IT within 4 weeks of SRS (concurrent) and 31.7% received SRS alone or non-concurrently with IT. Overall, BM local control rate was 87.1% after SRS. Median progression free survival was 8.7 months. Median follow-up was 29.2 months. On multivariate analysis (MVA), patients receiving concurrent SRS-IT maintained a higher chance of achieving a complete (CR) or partial response (PR) [HR 2.6 (95% CI: 1.2-5.5, P = 0.012)] and a reduced likelihood of progression of disease (PD) [HR 0.52 (95% CI: 0.16-0.60), P = 0.048]. Any increase in BM volume on the initial MRI 3 months after SRS predicted a lower likelihood of achieving long-term CR or PR on MVA accounting for concurrent IT, BRAF status and dexamethasone use [HR = 0.048 (95% CI: 0.007-0.345, P = 0.0026)]. Stratified volumetric change demonstrated a sequential relationship with outcomes on Kaplan-Meier analysis.Concurrent SRS-IT has favourable clinical and radiological outcomes with respect to CR, PR and a reduced likelihood of PD. Changes in BM volume on the initial MRI 3 months after SRS were predictive of long-term outcomes for treatment response.
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- 2022
26. A hyperparameter‐tuning approach to automated inverse planning
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K, Maass, A, Aravkin, and M, Kim
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Organs at Risk ,FOS: Computer and information sciences ,Computer Science - Machine Learning ,Radiotherapy Planning, Computer-Assisted ,FOS: Physical sciences ,Bayes Theorem ,Radiotherapy Dosage ,General Medicine ,Radiosurgery ,Physics - Medical Physics ,Machine Learning (cs.LG) ,Humans ,Radiotherapy, Intensity-Modulated ,Medical Physics (physics.med-ph) ,65K10, 90C26, 97M60 ,Retrospective Studies - Abstract
Radiotherapy inverse planning often requires planners to modify parameters in the treatment planning system's objective function to produce clinically acceptable plans. Due to the manual steps in this process, plan quality can vary depending on the planning time available and the planner's skills. This study investigates two hyperparameter-tuning methods for automated inverse planning. Because this framework does not train a model on previously-optimized plans, it can be readily adapted to practice pattern changes, and plan quality is not limited by that of a training cohort. We selected 10 patients who received lung SBRT using manually-generated clinical plans. We used random sampling (RS) and Bayesian optimization (BO) to tune parameters using linear-quadratic utility functions based on 11 clinical goals. Normalizing all plans to have PTV D95 equal to 48 Gy, we compared plan quality for the automatically-generated and manually-generated plans. We also investigated the impact of iteration count on the automatically-generated plans, comparing planning time and plan utility for RS and BO plans with and without stopping criteria. Without stopping criteria, the median planning time was 1.9 and 2.3 hours for RS and BO plans. The OAR doses in the RS and BO plans had a median percent difference (MPD) of 48.7% and 60.4% below clinical dose limits and an MPD of 2.8% and 3.3% below clinical plan doses. With stopping criteria, the utility decreased by an MPD of 5.3% and 3.9% for RS and BO plans, but the median planning time was reduced to 0.5 and 0.7 hours, and the OAR doses still had an MPD of 42.9% and 49.7% below clinical dose limits and an MPD of 0.3% and 1.8% below clinical plan doses. This study demonstrates that hyperparameter-tuning approaches to automated inverse planning can reduce active planning time with plan quality that is similar to or better than manually-generated plans., Comment: 22 pages, 4 figures
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- 2022
27. High local failure rates despite high margin‐negative resection rates in a cohort of borderline resectable and locally advanced pancreatic cancer patients treated with stereotactic body radiation therapy following multi‐agent chemotherapy
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Colin Hill, Shuchi Sehgal, Wei Fu, Chen Hu, Abhinav Reddy, Elizabeth Thompson, Amy Hacker‐Prietz, Dung Le, Ana De Jesus‐Acosta, Valerie Lee, Lei Zheng, Daniel A. Laheru, William Burns, Matthew Weiss, Christopher Wolfgang, Jin He, Joseph M. Herman, Jeffrey Meyer, and Amol Narang
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Pancreatic Neoplasms ,Cancer Research ,Oncology ,Antineoplastic Combined Chemotherapy Protocols ,Humans ,Radiology, Nuclear Medicine and imaging ,Adenocarcinoma ,Radiosurgery ,Neoadjuvant Therapy ,Retrospective Studies - Abstract
Stereotactic body radiation therapy (SBRT) for patients with borderline resectable and locally advanced pancreatic adenocarcinoma (BRPC/LAPC) remains controversial. Herein, we report on surgical, pathologic, and survival outcomes in BRPC/LAPC patients treated at a high-volume institution with induction chemotherapy (CTX) followed by 5-fraction SBRT.BRPC/LAPC patients treated between 2016 and 2019 were retrospectively reviewed. Surgical and pathological outcomes were descriptively characterized. Overall survival (OS) and progression-free survival (PFS) were analyzed using Cox proportional hazard regression. Locoregional failure and distant failure were analyzed with Fine-Gray competing risk model.Of 155 patients, 91 (59%) had LAPC and 64 (41%) had BRPC. Almost all were treated with induction multi-agent CTX with either FOLFIRINOX (75%) or gemcitabine and nab-paclitaxel (24%) for a median duration of 4.0 months (1-18 months). All received SBRT to a median dose of 33 Gy. Among 64 BRPC patients, 50 (78%) underwent resection, of whom 48 (96%) achieved margin-negative (R0) resection. Among 91 LAPC patients, 57 (63%) underwent resection, of whom 50 (88%) achieved R0 resection. Despite the high R0 rate, 33% of patients experienced locoregional failure, which was a component of 44% of all failures. After SBRT, median OS and PFS were 18.7 and 7.7 months, respectively. After SBRT, 1- and 2-year OS probabilities were 70% and 45%, whereas, from diagnosis, they were 93% and 51%.Although a high proportion of BRPC/LAPC patients treated with induction multi-agent CTX followed by SBRT successfully achieved R0 resection, locoregional failure remained common, highlighting the need to continue to optimize radiation delivery in this context.
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- 2022
28. Feasibility of isodose‐shaped scintillation detectors for the measurement of gamma knife output factors
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Tae Hoon Kim, Hye Jeong Yang, Jae Young Jeong, Thomas Schaarschmidt, Yong Kyun Kim, and Hyun‐Tai Chung
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Phantoms, Imaging ,Feasibility Studies ,General Medicine ,Radiometry ,Radiosurgery ,Monte Carlo Method - Abstract
Scintillation detectors were 3D printed based on a gamma knife (GK) dose distribution to calculate the volume averaging effect. The collimator output factors were measured using isodose-shaped scintillators (ISSs) and compared with those of a micro-diamond detector and previous reports.An absorbed dose distribution in a spherical dosimetry phantom with a radius of 8 cm was obtained from GK treatment planning software (Leksell GammaPlan [LGP], Elekta AB, Stockholm, Sweden). Two types of ISSs were fabricated to fit the 97.2% (ISS-1) and 95.6% (ISS-2) isodose surfaces. The volume averaging correction factors were obtained by dividing the absorbed dose to water in the central voxel (CV) by that in the ISS. The correction effect due to the difference between the ISS and water was calculated by Monte Carlo simulations. Ten ISS detectors, five of each type, were used to measure the output factors of the 4- and 8-mm collimators of a GK Icon to assess system consistency. The output factors of seven GKs were measured using two ISS detectors, one of each type, and a PTW T60019 (PTW, Freiburg, Germany) micro-diamond detector.The detector output ratios (DORs) measured using the five ISSs of each type were consistent, with standard uncertainties less than 0.2%. In the 4-mm field, the volume averaging correction factor ratios were 1.018 and 1.026, and the output factors after all corrections were 0.827 (0.006) and 0.825 (0.006) for ISS-1 and ISS-2, respectively. In the 8-mm field, the volume averaging correction factor ratios were 1.000 for both ISS types, and the output factors were 0.898 (0.003) and 0.900 (0.003) for ISS-1 and ISS-2, respectively. The ISS detectors could measure the output factors of a GK with uncertainties comparable to that of the PTW 60019 detector. The output factors of all detectors decreased with the dose rate.The volume averaging effect of an ISS developed in-house could be calculated using known dose distributions. The collimator output factors of the GK Perfexion/Icon models measured using ISS detectors were consistent with those of a commercial synthetic micro-diamond detector and recent studies.
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- 2022
29. Impact of Social Determinants of Health on Stereotactic Radiotherapy for Vestibular Schwannoma
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Amar D. Desai, Vraj P. Shah, Christopher C. Tseng, Roman Povolotskiy, P. Ashley Wackym, and Yu‐Lan Mary Ying
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Treatment Outcome ,Otorhinolaryngology ,Social Determinants of Health ,Quality of Life ,Humans ,Neuroma, Acoustic ,Radiosurgery ,Retrospective Studies - Abstract
Linear accelerator (LINAC) and Gamma Knife (GK) are common stereotactic radiation therapies for treating vestibular schwannoma (VS). There is currently limited literature examining specific demographic and socioeconomic factors, which influence the type of stereotactic radiation therapy a patient with VS receives.Retrospective database review.The National Cancer Database was queried for cases of VS between 2004 and 2016. Patient demographic characteristics were compared using chi-squared and t-tests between GK and LINAC treated groups. Multivariate regression analysis was performed to assess predictors of stereotactic radiation therapy received.Of the 6,208 included patients, 5,306 (85.5%) received GK and 902 (14.5%) received LINAC. The mean age of GK patients was significantly lower than that of LINAC patients (58.0 vs. 59.7, P .001). Individuals treated with GK had greater proportions of private insurance (P .001) and incomes greater than $63,332 (P = .003). A greater proportion of GK patients were treated in academic centers (P .001), in high-volume facilities (P .001), in metropolitan areas (P .001), and in the Northeastern United States (P .001). On multivariate logistic regression analysis, region, metropolitan area, facility type, tumor size, and distance traveled by patients independently predict receipt of GK versus LINAC.Differences in patient demographics and other social determinants of health influence choice of GK versus LINAC therapy for VS patients. Future studies focused on addressing barriers to care, which may influence postprocedural quality of life and clinical outcomes associated with these two treatments are necessary to better understand the impact of these social differences.4 Laryngoscope, 132:2232-2240, 2022.
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- 2022
30. Radiation necrosis in renal cell carcinoma brain metastases treated with checkpoint inhibitors and radiosurgery: An international multicenter study
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Eric J. Lehrer, Jason Gurewitz, Kenneth Bernstein, Dev Patel, Douglas Kondziolka, Ajay Niranjan, Zhishuo Wei, L. Dade Lunsford, Timothy D. Malouff, Henry Ruiz‐Garcia, Samir Patel, Phillip A. Bonney, Lindsay Hwang, Cheng Yu, Gabriel Zada, David Mathieu, Claire Trudel, Rahul N. Prasad, Joshua D. Palmer, Brianna M. Jones, Sonam Sharma, Kareem R. Fakhoury, Chad G. Rusthoven, Christopher P. Deibert, Piero Picozzi, Andrea Franzini, Luca Attuati, Cheng‐Chia Lee, Huai‐Che Yang, Manmeet S. Ahluwalia, Jason P. Sheehan, and Daniel M. Trifiletti
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Necrosis ,Cancer Research ,Oncology ,Brain Neoplasms ,Humans ,Cranial Irradiation ,Radiosurgery ,Carcinoma, Renal Cell ,Kidney Neoplasms ,Aged ,Retrospective Studies - Abstract
Patients with renal cell carcinoma (RCC) brain metastases are frequently treated with immune checkpoint inhibitors (ICIs) and stereotactic radiosurgery (SRS). However, data reporting on the risk of developing radiation necrosis (RN) are limited.RN rates were compared for concurrent therapy (ICI/SRS administration within 4 weeks of one another) and nonconcurrent therapy with the χFifty patients (23 concurrent and 27 nonconcurrent) with 395 brain metastases were analyzed. The median follow-up was 12.1 months; the median age was 65 years. The median margin dose was 20 Gy, and 4% underwent prior whole-brain radiation therapy (WBRT). The median treated tumor volume was 3.32 cmSymptomatic RN occurs in a minority of patients with RCC brain metastases treated with ICI/SRS. The majority of events were grade 1 to 3 and were managed medically. Concurrent ICI/SRS does not appear to increase this risk. Attempts to improve dose conformality (reduce V12) may be the most successful mitigation strategy in single-fraction SRS.
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- 2022
31. Outcomes of dogs with thymoma treated with intensity modulated stereotactic body radiation therapy or non‐modulated hypofractionated radiation therapy
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Erin Trageser, Tiffany Martin, Elizabeth Hoaglund, Del Leary, Susan LaRue, and Mary‐Keara Boss
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Dogs ,Thymoma ,General Veterinary ,Animals ,Dog Diseases ,Thymus Neoplasms ,Radiation Injuries ,Radiosurgery ,Retrospective Studies - Abstract
Canine thymomas are routinely treated with radiotherapy (RT). In this study, we investigate the response and toxicity of canine thymoma treated with intensity-modulated stereotactic body radiation therapy (SBRT) relative to dogs treated with hypofractionated non-modulated radiation therapy (NMRT). A retrospective study was performed of dogs with thymoma treated with RT (total: n = 15; SBRT: n = 8, NMRT: n = 7). Tumour response was evaluated in six dogs (40%); following SBRT, three dogs (100%) experienced stable disease (SD); following NMRT, one dog (33%) had a PR, and two dogs (67%) had SD. Median PFS was 116 days (range 66-727 days) for the SBRT group and 134 days (range 10-405 days) for the NMRT group. The MST for the SBRT group was 250 days (range 1-727 days) and 155 days (range 10-405 days) for NMRT. Median disease-specific survival was 250 days (range 1-727 days) for the SBRT group and 169 days (range 20-405 days) for the NMRT group. No significant differences in survival data were found between the treatment groups, however the results from the small number of dogs analysed are likely underpowered for statistical comparisons. Reported acute and late side effects were limited to the lungs and heart and were statistically significantly more common in the NMRT (71%) compared to the SBRT group (25%) (p = .04). We suggest similar treatment efficacy may be provided for canine thymoma treated with either approach, but SBRT could provide the clinical benefit of reduced incidence of radiation-induced toxicity and completion of RT in a shorter time frame.
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- 2022
32. Treatment patterns and clinical outcomes for patients with melanoma and central nervous system metastases: A real‐world study
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Hussein Tawbi, Tu My To, Karen Bartley, Natalia Sadetsky, Elizabeth Burton, Lauren Haydu, and Edward McKenna
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Male ,Cancer Research ,Brain Neoplasms ,overall survival ,Clinical Cancer Research ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,systemic treatment ,Middle Aged ,Radiosurgery ,Survival Analysis ,Oncology ,CNS metastases ,melanoma ,Humans ,Radiology, Nuclear Medicine and imaging ,Female ,Cranial Irradiation ,Immune Checkpoint Inhibitors ,Research Articles ,radiotherapy ,RC254-282 ,Aged ,Retrospective Studies ,Research Article - Abstract
Background Patients with melanoma and central nervous system (CNS) metastases have poor survival outcomes. We investigated real‐world treatment patterns and overall survival (OS) of patients with melanoma and CNS metastases. Methods A retrospective analysis utilizing a nationwide de‐identified electronic health record‐derived database was undertaken in patients diagnosed with advanced melanoma between January 2011 and September 2018. Patients with any visit ≤90 days of metastatic diagnosis and with confirmed CNS metastases were included. Results Of 3473 patients diagnosed with advanced melanoma, 791 patients with confirmed CNS metastases were identified and included in this analysis. Synchronous CNS metastasis (≤30 days of metastatic diagnosis) was associated with longer median OS than metachronous CNS metastasis (>30 days after metastatic diagnosis, 0.58 vs 0.42 years). Stereotactic radiosurgery (SRS) was the most common treatment (40.5%) alone or in combination with other local or systemic therapies, being more frequent in patients diagnosed in 2015+ versus 2011–2014 (44.1% vs 35.5%, respectively). The most common systemic treatment was immune checkpoint inhibitors (ICIs; 30.5%), predominantly anti‐cytotoxic T‐lymphocyte antigen 4 (CTLA‐4) alone (2011–2014) and anti‐programmed death‐1 alone or in combination with anti–CTLA‐4 (2015+). Median OS was longest in SRS‐treated patients (1.17 years) regardless of number of CNS metastases. Median OS for SRS‐treated patients increased from 0.83 years (2011–2014) to 1.75 years (2015+). In multivariable analysis, the effect of SRS remained significant after adjustment for sex, race, intracranial and extracranial disease burden, and timing of CNS metastases. Interaction testing to examine potential synergy between SRS/whole‐brain radiation therapy and ICIs found no significant interaction. Conclusions Despite advances in treatment, patients with melanoma and CNS metastases have poor survival outcomes. Prevalence of SRS increased over time and was associated with improved outcomes., This retrospective analysis of real‐world data demonstrated that patients with melanoma and CNS metastases have poor survival outcomes despite recent advances in treatment options. Prevalence of stereotactic radiosurgery increased over time and was associated with improved outcomes.
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- 2022
33. Stereotactic radiotherapy as planned boost after definitive radiotherapy for head and neck cancers: Systematic review
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Michael S. Kim, Nauman H. Malik, Hanbo Chen, Ian Poon, Zain Husain, Antoine Eskander, Gabriel Boldt, Alexander V. Louie, and Irene Karam
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Survival Rate ,Otorhinolaryngology ,Head and Neck Neoplasms ,Humans ,Radiosurgery ,Neck - Abstract
Management of locoregionally advanced head and neck cancers (HNCs) remains a challenge. Some groups have attempted to use stereotactic radiotherapy (SBRT) to deliver "boost" treatment following conventional radiotherapy to improve local control (LC) and overall survival (OS), while aiming for acceptable toxicities. Medline, EMBASE, and Cochrane Library databases were queried for SBRT as curative-intent planned boost in HNC after conventional radiotherapy. Individual studies were reviewed from inception until January 2021, extracting patient, treatment, and outcome data. Nine studies met inclusion criteria, representing 454 unique patients treated with curative intent across multiple head and neck sites with conventional radiotherapy. At 3 years, median LC was 92% (90%-98%), and median OS was 80% (75%-91%). Seven treatment-related grade 5 toxicities (1.5%) were reported. Despite acceptable LC and OS rates, there were severe treatment-related late toxicities. As such, SBRT boost should only be used in investigational settings until more data is available.
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- 2021
34. Cost‐effectiveness of carbon‐ion radiotherapy versus stereotactic body radiotherapy for non‐small‐cell lung cancer
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Yuhei Miyasaka, Tomoyuki Takura, Tatsuya Ohno, Hidemasa Kawamura, Kei Shibuya, and Shohei Okazaki
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Cancer Research ,medicine.medical_specialty ,Lung Neoplasms ,Cost effectiveness ,Cost-Benefit Analysis ,medicine.medical_treatment ,Heavy Ion Radiotherapy ,Radiosurgery ,Japan ,Carcinoma, Non-Small-Cell Lung ,medicine ,Humans ,Lung cancer ,health care economics and organizations ,business.industry ,Health Care Costs ,General Medicine ,Cost-effectiveness analysis ,medicine.disease ,Radiation therapy ,Regimen ,Treatment Outcome ,Oncology ,Carbon Ion Radiotherapy ,Radiology ,Non small cell ,business ,Stereotactic body radiotherapy - Abstract
Carbon-ion radiotherapy (CIRT) for clinical stage I non-small-cell lung cancer (NSCLC) is used as an advanced medical treatment regimen in Japan. Carbon-ion radiotherapy reportedly aids in achieving excellent treatment outcomes, despite its high medical cost. We aimed to compare CIRT with stereotactic body radiotherapy (SBRT) in terms of cost-effectiveness for treating clinical stage I NSCLC. Data of patients with clinical stage I NSCLC treated with CIRT or SBRT at Gunma University between 2010 and 2015 were analyzed. The CIRT and SBRT groups included 62 and 27 patients, respectively. After propensity-score matching, both groups comprised 15 patients. Life year (LY) was used as an indicator of outcome. The CIRT technical fee was 3 140 000 JPY. There was no technical fee for the second CIRT carried out on the same organ within 2 years. The incremental cost-effectiveness ratio (ICER) was calculated by dividing the incremental cost by the incremental LY for 5 years after treatment. Sensitivity analysis was applied to evaluate the impact of LY or costs of each group on ICER. The ICERs were 7 491 017 JPY/LY and 3 708 330 JPY/LY for all patients and matched patients, respectively. Hospitalization and examination costs were significantly higher in the CIRT group, and the impact of the CIRT technical costs was smaller than other costs and LY. Carbon-ion radiotherapy is a cost-effective treatment approach. However, our findings suggest that reducing excessive costs by considering the validity and necessity of examinations and hospitalizations would make CIRT a more cost-effective approach.
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- 2021
35. New dosimetric guidelines for linear Boltzmann transport equations through comparative evaluation of stereotactic body radiation therapy for lung treatment planning
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Deepinder P. Singh, Kenneth Y. Usuki, Michael T. Milano, Amy Herman, Matthew Webster, Neil Joyce, Yuhchyau Chen, Louis S. Constine, Inhwan Yeo, and Sean Tanny
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Lung Neoplasms ,Acuros XB ,Stereotactic body radiation therapy ,Planning target volume ,planning guidelines ,Radiosurgery ,lung ,Comparative evaluation ,Retrospective analysis ,Humans ,Radiation Oncology Physics ,Radiology, Nuclear Medicine and imaging ,Radiation treatment planning ,Instrumentation ,Retrospective Studies ,Mathematics ,SBRT ,Radiation ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Radiotherapy Dosage ,Acuros xb ,Radiotherapy, Intensity-Modulated ,Nuclear medicine ,business ,Previously treated ,Algorithms - Abstract
Purpose To propose guidelines for lung stereotactic body radiation therapy (SBRT) when using Acuros XB (AXB) equivalent to the existing ones developed for convolution algorithms such as analytic anisotropic algorithm (AAA), considering the difference between the algorithms. Methods A retrospective analysis was performed on 30 lung patients previously treated with SBRT. The original AAA plans, which were developed using dynamic conformal arcs, were recalculated and then renormalized for planning target volume (PTV) coverage using AXB. The recalculated and renormalized plans were compared to the original plans based on V100% and V90% PTV coverage, as well as V105%, conformality index, D2cm , Rx/Dmax , R50, and Dmin . These metrics were analyzed nominally and on variations according to RTOG and NRG guidelines. Based on the relative difference between each metric in the AAA and AXB plans, new guidelines were developed. The relative differences in our cohort were compared to previously documented AAA to AXB comparisons found in the literature. Results AAA plans recalculated in AXB had a significant reduction in most dosimetric metrics. The most notable changes were in V100% (4%) and the conformality index (7.5%). To achieve equal PTV coverage, AXB required an average of 1.8% more monitor units (MU). This fits well with previously published data. Applying the new guidelines to the AXB plans significantly increased the number of minor violations with no change in major violations, making them comparable to those of the original AAA plans. Conclusion The relative difference found between AAA and AXB for SBRT lung plans has been shown to be consistent with previous works. Based on these findings, new guidelines for lung SBRT are recommended when planning with AXB.
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- 2021
36. Application of an automatic, uncertainty model‐guided, target‐generating algorithm to lung stereotactic body radiotherapy
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Evan C. Osmundson, Adam D. Yock, and Ashley Knutson
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Uncertainty model ,Lung Neoplasms ,Lung ,Computer science ,medicine.medical_treatment ,Uncertainty ,Image registration ,General Medicine ,Radiosurgery ,computer.software_genre ,Radiation therapy ,medicine.anatomical_structure ,Margin (machine learning) ,Voxel ,medicine ,Humans ,computer ,Algorithm ,Algorithms ,Volume (compression) ,Image-guided radiation therapy - Abstract
PURPOSE This work evaluated a new radiotherapy target-generating framework (the αTarget algorithm) for creating internal target volumes for lung SBRT. METHODS Nineteen patients previously treated with definitive intent SBRT to the lung were identified from a clinical database. For each patient's 4DCT simulation scan, deformable image registration was used between phases of the scan in order to generate voxelized models of motion for 35 individual gross tumor volumes. These motion models were then used with a new implementation of a previously described target-generating algorithm to create new internal target volumes (αITVs). The resulting αITVs were analyzed with respect to their volume and the coverage they provided each tumor voxel per that voxel's motion model. The clinically used ITVs were similarly analyzed, and were then compared to the αITVs using paired Student's t-tests. In addition, isotropic margins were added to the αITVs in order to determine the largest margin magnitude that could be added without exceeding the volume of the clinical ITVs. RESULTS The αITVs increased the target coverage provided to each tumor's 5th-percentile-most-covered-voxel an average of 50.3% compared to the clinical ITVs (p
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- 2021
37. Optimization of treatment isocenter location in single‐isocenter LINAC‐based stereotactic radiosurgery for management of multiple brain metastases
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Ning J. Yue, Yongkang Zhou, Ke Nie, Yin Zhang, Taoran Cui, Irina Vergalasova, and Jiahua Zhu
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Sample average ,Brain Neoplasms ,business.industry ,Radiotherapy Planning, Computer-Assisted ,medicine.medical_treatment ,Planning target volume ,Isocenter ,Radiotherapy Dosage ,General Medicine ,Dose distribution ,Radiosurgery ,Standard deviation ,Linear particle accelerator ,medicine ,Range (statistics) ,Humans ,Nuclear medicine ,business ,Retrospective Studies ,Mathematics - Abstract
PURPOSE Single-isocenter linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) has become a promising treatment technique for the management of multiple brain metastases. Because of the high prescription dose and steep dose gradient, SRS plans are sensitive to geometric errors, resulting in loss of target coverage and suboptimal local tumor control. Current planning techniques rely on adding a uniform and isotropic setup margin to all gross tumor volumes (GTVs) to account for rotational uncertainties. However, this setup margin may be insufficient, since the magnitude of rotational uncertainties varies and is dependent upon the distance between a GTV and the isocenter. In this study, we designed a framework to determine the optimal isocenter of a single-isocenter SRS plan for multiple brain metastases using stochastic optimization to mitigate potential errors resulting from rotational uncertainties. METHODS Planning target volumes (PTVs), defined as GTVs plus a 1-mm margin following common SRS planning convention, were assumed to be originally treated with a prescription dose and therefore covered by the prescription isodose cloud. The dose distribution, including the prescription isodose, was considered invariant assuming small rotations throughout the study. A stochastic optimization scheme was developed to determine the location of the optimal isocenter, so that the prescription dose coverage of rotated GTVs, equivalent to the intersecting volumes between the rotated GTVs and original PTVs, was maximized for any random small rotations about the isocenter. To evaluate the coverage of GTVs, the expected V100% undergoing random rotations was approximated as the sample average V100% undergoing a predetermined number of rotations. The expected V100% of each individual GTV and total GTVs was then compared between the plans using the optimal isocenter and the center-of-mass (CoM), respectively. RESULTS Twenty-two patients previously treated for multiple brain metastases in a single institute were included in this retrospective study. Each patient was initially treated for more than three brain metastases (mean: 7.6; range: 3-15) with the average GTV volume of 0.89 cc (range: 0.03-11.78 cc). The optimal isocenter found for each patient was significantly different from the CoM, with the average Euclidean distance between the optimal isocenter and the CoM being 4.36 ± 2.59 cm. The dose coverage to GTVs was also significantly improved (paired t-test; p
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- 2021
38. Decompose kV projection using neural network for improved motion tracking in paraspinal SBRT
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Xiuxiu He, John J. Cuaron, Laura Cervino, Qiyong Fan, Weixing Cai, Feifei Li, Pengpeng Zhang, Xiang Li, and Tianfang Li
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Image-Guided Therapy ,Discriminator ,Mean squared error ,Artificial neural network ,Computer science ,business.industry ,Radiography ,General Medicine ,Signal-To-Noise Ratio ,Radiosurgery ,Tracking (particle physics) ,Article ,Spine ,Motion ,Match moving ,Humans ,Computer vision ,Neural Networks, Computer ,Artificial intelligence ,Projection (set theory) ,business - Abstract
PURPOSE On-treatment kV images have been used in tracking patient motion. One challenge of markerless motion tracking in paraspinal SBRT is the reduced contrast when the X-ray beam needs to pass through a large portion of the patient's body, for example, from the lateral direction. Besides, due to the spine's overlapping with the surrounding moving organs in the X-ray images, auto-registration could lead to potential errors. This work aims to automatically extract the spine component from the conventional 2D X-ray images, to achieve more robust and more accurate motion management. METHODS A ResNet generative adversarial network (ResNetGAN) consisting of one generator and one discriminator was developed to learn the mapping between 2D kV image and the reference spine digitally reconstructed radiograph (DRR). A tailored multi-channel multi-domain loss function was used to improve the quality of the decomposed spine image. The trained model took a 2D kV image as input and learned to generate the spine component of the X-ray image. The training dataset included 1347 2D kV thoracic and lumbar region X-ray images from 20 randomly selected patients, and the corresponding matched reference spine DRR. Another 226 2D kV images from the remaining four patients were used for evaluation. The resulted decomposed spine images and the original X-ray images were registered to the reference spine DRRs, to compare the spine tracking accuracy. RESULTS The decomposed spine image had the mean peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) of 60.08 and 0.99, respectively, indicating the model retained and enhanced the spine structure information in the original 2D X-ray image. The decomposed spine image matching with the reference spine DRR had submillimeter accuracy (in mm) with a mean error of 0.13, 0.12, and a maximum of 0.58, 0.49 in the x - and y -directions (in the imager coordinates), respectively. The accuracy improvement is robust in all lateral and anteroposterior X-ray beam angles. CONCLUSION We developed a deep learning-based approach to remove soft tissues in the kV image, leading to more accurate spine tracking in paraspinal SBRT.
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- 2021
39. SBRT of ventricular tachycardia using 4pi optimized trajectories
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James Robar, Brian Little, Alasdair Syme, Christopher G. Thomas, Macdonald Robert Lee, and Cristiano Q. M. Reis
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Organs at Risk ,Thorax ,Vena Cava, Superior ,medicine.medical_treatment ,Ventricular tachycardia ,Inferior vena cava ,Radiosurgery ,Superior vena cava ,medicine.artery ,Humans ,Radiation Oncology Physics ,Medicine ,Radiology, Nuclear Medicine and imaging ,Esophagus ,Instrumentation ,Aorta ,SBRT ,Radiation ,business.industry ,Radiotherapy Planning, Computer-Assisted ,radiosurgery ,Radiotherapy Dosage ,medicine.disease ,Spinal cord ,4pi trajectories ,medicine.anatomical_structure ,medicine.vein ,Tachycardia, Ventricular ,Radiotherapy, Intensity-Modulated ,ventricular tachycardia ,business ,Nuclear medicine - Abstract
Purpose To investigate the possible advantages of using 4pi‐optimized arc trajectories in stereotactic body radiation therapy of ventricular tachycardia (VT‐SBRT) to minimize exposure of healthy tissues. Methods and materials Thorax computed tomography (CT) data for 15 patients were used for contouring organs at risk (OARs) and defining realistic planning target volumes (PTVs). A conventional trajectory plan, defined as two full coplanar arcs was compared to an optimized‐trajectory plan provided by a 4pi algorithm that penalizes geometric overlap of PTV and OARs in the beam's‐eye‐view. A single fraction of 25 Gy was prescribed to the PTV in both plans and a comparison of dose sparing to OARs was performed based on comparisons of maximum, mean, and median dose. Results A significant average reduction in maximum dose was observed for esophagus (18%), spinal cord (26%), and trachea (22%) when using 4pi‐optimized trajectories. Mean doses were also found to decrease for esophagus (19%), spinal cord (33%), skin (18%), liver (59%), lungs (19%), trachea (43%), aorta (11%), inferior vena cava (25%), superior vena cava (33%), and pulmonary trunk (26%). A median dose reduction was observed for esophagus (40%), spinal cord (48%), skin (36%), liver (72%), lungs (41%), stomach (45%), trachea (53%), aorta (45%), superior vena cava (38%), pulmonary veins (32%), and pulmonary trunk (39%). No significant difference was observed for maximum dose (p = 0.650) and homogeneity index (p = 0.156) for the PTV. Average values of conformity number were 0.86 ± 0.05 and 0.77 ± 0.09 for the conventional and 4pi optimized plans respectively. Conclusions 4pi optimized trajectories provided significant reduction to mean and median doses to cardiac structures close to the target but did not decrease maximum dose. Significant improvement in maximum, mean and median doses for noncardiac OARs makes 4pi optimized trajectories a suitable delivery technique for treating VT.
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- 2021
40. CT characteristics and proposed scoring scheme are predictive of pathologic fracture in dogs with appendicular osteosarcoma treated with stereotactic body radiation therapy
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Tiffany Martin, Lynn Griffin, and Susan M. LaRue
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Osteosarcoma ,medicine.medical_specialty ,General Veterinary ,business.industry ,Stereotactic body radiation therapy ,Pathologic fracture ,medicine.medical_treatment ,Bone Neoplasms ,Sequela ,Odds ratio ,Radiosurgery ,medicine.disease ,Radiation therapy ,Dogs ,Fractures, Spontaneous ,Normal bone ,Quartile ,medicine ,Animals ,Dog Diseases ,Radiology ,Tomography, X-Ray Computed ,business ,Retrospective Studies - Abstract
Stereotactic body radiation therapy (SBRT) is an established limb-sparing treatment for dogs with appendicular osteosarcoma (OSA) and pathologic fractures are a common sequela. The objectives of this retrospective, observational, and descriptive study were to develop and evaluate objective CT criteria for predicting pathologic fractures and assess impacts on survival time. Included dogs had confirmed or suspected appendicular OSA, available CT scans, available outcome data, and were treated with SBRT. For each study, the number of quartiles affected by lysis on the most severely affected transverse slice, longest measurable length of contiguous full cortical lysis, presence of subchondral bone lysis, and ratio of the length of the affected bone to normal bone were recorded. A scoring system was developed for assigning grades (summed score 1-4 = grade 1, 5-7 = grade 2, and 8 or greater = grade 3.) A total of 127 CT datasets were sampled (123 patients). The median summed score was 7. The grade was correlated with pathologic fracture development (23% of grade 1, 35% of grade 2, and 57% of grade 3 resulting in fracture, P = 0.028). Subchondral bone lysis was correlated with fracture (odds ratio, 2.2, P = 0.02). Percent affected bone ≥40% was associated with decreased survival (P = 0.002). Dogs with
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- 2021
41. Value and significance of brain radiation therapy during first‐line <scp>EGFR‐TKI</scp> treatment in lung adenocarcinoma with <scp> EGFR </scp> sensitive mutation and synchronous brain metastasis: Appropriate timing and technique
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Ping Liu, Weijuan Jiang, Baoshan Cao, Yan Yu, Yuan Cheng, Li Liang, Hongqing Zhuang, Dahai Zhao, Yonggang Liu, Junzhen Gao, Yangchun Gu, Mengzhao Wang, Hua Zhang, Xiaofeng Li, Jianwen Qin, Yan Xu, Li Ma, and Xueqin Chen
- Subjects
Pulmonary and Respiratory Medicine ,Oncology ,medicine.medical_specialty ,Mutation ,Lung ,biology ,medicine.drug_class ,business.industry ,medicine.medical_treatment ,General Medicine ,medicine.disease ,medicine.disease_cause ,Tyrosine-kinase inhibitor ,Radiosurgery ,respiratory tract diseases ,Radiation therapy ,medicine.anatomical_structure ,Internal medicine ,medicine ,biology.protein ,Adenocarcinoma ,Epidermal growth factor receptor ,business ,Brain metastasis - Abstract
Background For lung adenocarcinoma patients with epidermal growth factor receptor (EGFR) sensitive mutation and synchronous brain metastasis (syn-BM), when and how to apply radiotherapy (RT) during first-line tyrosine kinase inhibitor (TKI) treatment remains debatable. Methods From a real-world multicenter database, EGFR-mutant patients with syn-BM diagnosed between 2010-2020 and treated with first-line TKIs were enrolled and divided into upfront TKI + RT and upfront TKI groups. Median intracranial progression-free survival (mIC-PFS), median overall survival (mOS), and their risk factors were estimated. Results There were 60 and 186 patients in the upfront TKI + RT group and upfront TKI group, respectively. Their mIC-PFS were 28.9 months (m) and 17.5 m (p = 0.023), and mOS were 42.7 m and 40.1 m (p = 0.51). Upfront brain RT improved mIC-PFS in patients ≤60-year-old (p = 0.035), with symptomatic BM (p = 0.002), and treated with first-generation TKIs (p = 0.012). There was no significant difference in mOS in any subgroup. Upfront brain stereotactic radiosurgery (SRS) showed a trend of better mIC-PFS and mOS. mIC-PFS was independently correlated with symptomatic BM (HR = 1.54, p = 0.030), EGFR L858R mutation (HR = 1.57, p = 0.019), and upfront brain RT (HR = 0.47, p = 0.001). mOS was independently correlated with being female (HR = 0.54, p = 0.007), ECOG 3-4 (HR = 10.47, p 3 (HR = 2.19, p = 0.002), and third-generation TKI (HR = 0.54, p = 0.044) or antiangiogenic drugs (HR = 0.11, p = 0.005) as first/second-line therapy. Conclusions Upfront brain RT based on first-line EGFR-TKI might improve IC-PFS but not OS in EGFR-mutant lung adenocarcinoma patients, indicating potential survival benefit from brain SRS and early application of drugs with higher intracranial activity.
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- 2021
42. Cardiac stereotactic body radiation therapy for ventricular tachycardia: Current experience and technical gaps
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Chen Wei, Raymond H. Mak, Jeremy S. Bredfeldt, Paul C. Zei, Ron Blankstein, Pierre Qian, Michelle Boeck, and Usha B. Tedrow
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medicine.medical_specialty ,Stereotactic body radiation therapy ,business.industry ,medicine.medical_treatment ,Arrhythmias, Cardiac ,Heart ,Catheter ablation ,Radiosurgery ,Ventricular tachycardia ,medicine.disease ,Radiation therapy ,Safety profile ,Physiology (medical) ,Catheter Ablation ,Tachycardia, Ventricular ,medicine ,Humans ,Treatment effect ,Cardiology and Cardiovascular Medicine ,business ,Intensive care medicine ,Stereotactic body radiotherapy - Abstract
Despite advances in drug and catheter ablation therapy, long-term recurrence rates for ventricular tachycardia remain suboptimal. Cardiac stereotactic body radiotherapy (SBRT) is a novel treatment that has demonstrated reduction of arrhythmia episodes and favorable short-term safety profile in treatment-refractory patients. Nevertheless, the current clinical experience is early and limited. Recent studies have highlighted variable duration of treatment effect and substantial recurrence rates several months postradiation. Contributing to these differential outcomes are disparate approaches groups have taken in planning and delivering radiation, owing to both technical and knowledge gaps limiting optimization and standardization of cardiac SBRT.In this report, we review the historical basis for cardiac SBRT and existing clinical data. We then elucidate the current technical gaps in cardiac radioablation, incorporating the current clinical experience, and summarize the ongoing and needed efforts to resolve them.Cardiac SBRT is an emerging therapy that holds promise for the treatment of ventricular tachycardia. Technical gaps remain, to be addressed by ongoing research and growing clincial experience.
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- 2021
43. Predicting the effect of indirect cell kill in the treatment of multiple brain metastases via single‐isocenter/multitarget volumetric modulated arc therapy stereotactic radiosurgery
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Allison N Palmiero, Denise Fabian, William H. St. Clair, Damodar Pokhrel, and Marcus E. Randall
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SIMT‐VMAT SRS ,medicine.medical_treatment ,Planning target volume ,Radiosurgery ,multiple brain metastases ,direct/indirect cell kill ,Cell kill ,medicine ,Humans ,Radiation Oncology Physics ,Dosimetry ,Radiology, Nuclear Medicine and imaging ,Instrumentation ,High rate ,Radiation ,setup uncertainties ,Brain Neoplasms ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Isocenter ,Radiotherapy Dosage ,Volumetric modulated arc therapy ,Gross tumor volume ,Radiotherapy, Intensity-Modulated ,Nuclear medicine ,business - Abstract
Purpose Due to spatial uncertainty, patient setup errors are of major concern for radiosurgery of multiple brain metastases (m‐bm) when using single‐isocenter/multitarget (SIMT) volumetric modulated arc therapy (VMAT) techniques. However, recent clinical outcome studies show high rates of tumor local control for SIMT‐VMAT. In addition to direct cell kill (DCK), another possible explanation includes the effects of indirect cell kill (ICK) via devascularization for a single dose of 15 Gy or more and by inducing a radiation immune intratumor response. This study quantifies the role of indirect cell death in dosimetric errors as a function of spatial patient setup uncertainty for stereotactic treatments of multiple lesions. Material and Methods Nine complex patients with 61 total tumors (2‐16 tumors/patient) were planned using SIMT‐VMAT with geometry similar to HyperArc with a 10MV‐FFF beam (2400 MU/min). Isocenter was placed at the geometric center of all tumors. Average gross tumor volume (GTV) and planning target volume (PTV) were 1.1 cc (0.02–11.5) and 1.9 cc (0.11–18.8) with an average distance to isocenter of 5.4 cm (2.2–8.9). The prescription was 20 Gy to each PTV. Plans were recalculated with induced clinically observable patient setup errors [±2 mm, ±2o] in all six directions. Boolean structures were generated to calculate the effect of DCK via 20 Gy isodose volume (IDV) and ICK via 15 Gy IDV minus the 20 Gy IDV. Contributions of each IDV to the PTV coverage were analyzed along with normal brain toxicity due to the patient setup uncertainty. Induced uncertainty and minimum dose covering the entire PTV were analyzed to determine the maximum tolerable patient setup errors to utilize the ICK effect for radiosurgery of m‐bm via SIMT‐VMAT. Results Patient setup errors of 1.3 mm /1.3° in all six directions must be maintained to achieve PTV coverage of the 15 Gy IDV for ICK. Setup errors of ±2 mm/2° showed clinically unacceptable loss of PTV coverage of 29.4 ± 14.6% even accounting the ICK effect. However, no clinically significant effect on normal brain dosimetry was observed. Conclusions Radiosurgery of m‐bm using SIMT‐VMAT treatments have shown positive clinical outcomes even with small residual patient setup errors. These clinical outcomes, while largely due to DCK, may also potentially be due to the ICK. Potential mechanisms, such as devascularization and/or radiation‐induced intratumor immune enhancement, should be explored to provide a better understanding of the radiobiological response of stereotactic radiosurgery of m‐bm using a SIMT‐VMAT plan.
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- 2021
44. Outcomes of Salvage Resection and Radiosurgery Following Failed Primary Treatment of Vestibular Schwannomas
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David R. Friedmann, J. Thomas Roland, John G. Golfinos, Sean O. McMenomey, Daniel Jethanamest, Emily Kay-Rivest, and Douglas Kondziolka
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Salvage Therapy ,medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,Neuroma, Acoustic ,Microsurgery ,Radiosurgery ,Surgery ,Resection ,Treatment Outcome ,Otorhinolaryngology ,Vestibular Schwannomas ,parasitic diseases ,medicine ,Humans ,Primary treatment ,business ,Follow-Up Studies ,Retrospective Studies - Abstract
To evaluate outcomes following salvage microsurgery (MS) and salvage stereotactic radiosurgery (SRS) after failure of primary treatment for vestibular schwannomas (VS).Retrospective chart review.Tertiary referral center.Patients with more than 1 intervention for their VS were divided into 4 groups: MS followed by SRS (n = 61), MS followed by MS (n = 9), SRS followed by MS (n = 7), and SRS followed by SRS (n = 7), and outcomes were evaluated.A total of 77 patients were included (84 procedures). In group 1 (MS then SRS), 3% developed a decline in facial function, 3% developed trigeminal sensory loss, and 13% patients had gradual improvement of facial nerve function following SRS. Group 2 (MS then MS) had the highest rates of facial nerve deterioration, although all but 1 patient achieved a House-Brackmann score of II or III. Gross-total resection (GTR) was achieved in 56% of patients. When a different approach was used for salvage resection, GTR occurred more commonly, and facial nerve outcomes were similar. In group 3 (SRS then MS), GTR occurred in 43% of cases, and 2 of 7 patients developed worsened facial function. In group 4 (SRS then SRS), no patient developed facial weakness after reirradiation, and 1 developed a trigeminal nerve deficit.For MS recurrences/residuals, SRS is the mainstay of treatment and does not preclude facial function recovery. If salvage microsurgery is required, an alternate approach should be considered. For SRS failures, when MS is required, less-than GTR may be preferable, and reirradiation is a potential safe alternative.
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- 2021
45. Late metastatic presentation is associated with improved survival and delayed wide‐spread progression after ablative stereotactic body radiotherapy for oligometastasis
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Arjun Sahgal, Umberto Ricardi, Hanbo Chen, Matthew Foote, Tithi Biswas, Kristin J. Redmond, Roi Dagan, Xuguang Chen, Darby Erler, Alexander V. Louie, Serena Badellino, and Ian Poon
- Subjects
Male ,Oncology ,Cancer Research ,Lung Neoplasms ,Colorectal cancer ,wide-spread progression ,Kaplan-Meier Estimate ,Metastasis ,Carcinoma, Non-Small-Cell Lung ,Research Articles ,RC254-282 ,SABR ,Aged, 80 and over ,SBRT ,Incidence ,Incidence (epidemiology) ,Hazard ratio ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,Middle Aged ,Prognosis ,Primary tumor ,metastasis‐directed radiotherapy ,Kidney Neoplasms ,Progression-Free Survival ,oligometastasis ,Disease Progression ,Female ,late metastasis ,metastasis-directed radiotherapy ,Colorectal Neoplasms ,Research Article ,Adult ,wide‐spread progression ,medicine.medical_specialty ,Breast Neoplasms ,Radiosurgery ,Internal medicine ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Aged ,business.industry ,Clinical Cancer Research ,Prostatic Neoplasms ,Cancer ,medicine.disease ,Confidence interval ,business ,Kidney cancer ,Follow-Up Studies - Abstract
Background Stereotactic body radiotherapy (SBRT) is increasingly used to treat oligometastatic disease (OMD), but the effect of metastasis timing on patient outcomes remains uncertain. Methods An international database of patients with OMD treated with SBRT was assembled with rigorous quality assurance. Early versus late metastases were defined as those diagnosed ≤24 versus >24 months from the primary tumor. Overall survival (OS), progression‐free survival (PFS), and incidences of wide‐spread progression (WSP) were estimated using multivariable Cox proportional hazard models stratified by primary tumor types. Results The database consists of 1033 patients with median follow‐up of 24.1 months (0.3–104.7). Late metastatic presentation (N = 427) was associated with improved OS compared to early metastasis (median survival 53.6 vs. 33.0 months, hazard ratio [HR] 0.59, 95% confidence interval [CI]: 0.47–0.72, p, Despite the increasing utilization of stereotactic body radiotherapy (SBRT) for patients with oligometastasic disease (OMD), prognostic and predictive factors for this treatment modality are not well understood. In this analysis of a large, multi‐institutional database of SBRT for OMD, the timing of metastatic presentation is a significant prognostic factor, as patients with late metastasis (>24 months from cancer diagnosis) have lower risk of widespread progression and death after SBRT.
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- 2021
46. Leksell Gamma Knife® – The first 1000 patients from the radiation therapist’s perspective
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Sara H. Olson, Angela McBean, Bruce Hall, Mark B. Pinkham, Heath Foley, Michael Jenkins, Catherine E. Jones, Ryan Lusk, and Matthew Foote
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medicine.medical_specialty ,intracranial ,workflow ,medicine.medical_treatment ,stereotactic radiosurgery ,R895-920 ,Gamma knife ,Treatment unit ,Radiosurgery ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Medical physics. Medical radiology. Nuclear medicine ,0302 clinical medicine ,Radiation oncology ,medicine ,High doses ,Radiology, Nuclear Medicine and imaging ,Medical physics ,Radiological and Ultrasound Technology ,business.industry ,Radiation Therapist ,Radiation therapy ,030220 oncology & carcinogenesis ,Neurosurgery ,business ,Leksell gamma knife - Abstract
The Princess Alexandra Hospital (PAH) Gamma Knife® Centre of Queensland (GKCoQ) began operations in October of 2015 as a sub‐specialty located within a larger radiation oncology service at PAH. It is uniquely positioned as the only Leksell Gamma Knife® (LGK) treatment unit available in the public hospital system in Australia, and the first and only service in Queensland. The GKCoQ treated the 1000th patient on 23 January 2019. LGK is a non‐invasive alternative to neurosurgery which uses radioactive cobalt sources to treat a variety of intracranial conditions ranging from tumours and metastases to functional disorders. It is a platform for stereotactic radiosurgery, a highly precise form of radiotherapy utilising very high doses to the target while maximally sparing surrounding normal brain. LGK enables patient planning and treatment to be done in one day as an outpatient procedure. This paper will outline our LGK service and provide insight into the expanded role that radiation therapists have within the multidisciplinary team required to deliver radiosurgery in a timely manner. The training programme and radiation licensing pathway that have been established for radiation therapists will also be described.
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- 2021
47. Stereotactic body radiotherapy using a hydrogel spacer for localized prostate cancer: A dosimetric comparison between tomotherapy with the newly‐developed tumor‐tracking system and cyberknife
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Yuta Shibamoto, Yoshihiko Manabe, Seiji Hashimoto, and Hideki Mukouyama
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Male ,medicine.medical_treatment ,tomotherapy ,Rectum ,Radiosurgery ,Tomotherapy ,Prostate cancer ,Cyberknife ,Prostate ,cyberknife ,Radiation Oncology Physics ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,Instrumentation ,Radiation ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Prostatic Neoplasms ,Hydrogels ,Radiotherapy Dosage ,prostate cancer ,medicine.disease ,medicine.anatomical_structure ,Urethra ,tumor‐tracking system ,Tumor tracking ,stereotactic radiotherapy ,Radiotherapy, Intensity-Modulated ,business ,Nuclear medicine ,Stereotactic body radiotherapy - Abstract
Purpose With a new tumor‐tracking system (Synchrony®) for tomotherapy (Radixact®), the internal and set‐up margins can be tightened, like cyberknife (CyberKnife®), in the planning of stereotactic body radiotherapy (SBRT) for prostate cancer. Recently, the usefulness of placing a hydrogel spacer between the prostate and rectum has been established in prostate radiotherapy. We evaluated the characteristics of tomotherapy plans with the tumor‐tracking system and compared them with cyberknife SBRT plans for localized prostate cancer using a hydrogel spacer. Methods In 20 patients, two plans were created and compared using tomotherapy and cyberknife. All patients underwent hydrogel spacer injection behind the prostate before simulation CT and MRI for fusion. For all plans, 36.25 Gy in 7.25‐Gy fractions for a minimum coverage dose of 95% of planning target volume (PTV) (D95%) was prescribed. The D99% of PTV and D0.1 ml of the PTV, urethra, bladder, and rectum were intended to be > 90%, 110–130%, 100–110%
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- 2021
48. Calculation algorithms and penumbra: Underestimation of dose in organs at risk in dosimetry audits
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Stephanie Keehan, Jeremy Hughes, Joerg Lehmann, Maddison Shaw, J R Supple, Tomas Kron, Jessica Lye, Fayz Kadeer, Francis Gibbons, and A. Alves
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Organs at Risk ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Penumbra ,Calculation algorithm ,Australia ,Radiotherapy Dosage ,General Medicine ,Radiosurgery ,computer.software_genre ,Planned Dose ,Voxel ,Maximum dose ,Ionization chamber ,Humans ,Medicine ,Dosimetry ,Radiotherapy, Intensity-Modulated ,Nuclear medicine ,business ,Monte Carlo Method ,Stereotactic body radiotherapy ,computer ,Algorithms - Abstract
PURPOSE: The aim of this study is to investigate overdose to organs at risk (OARs) observed in dosimetry audits in Monte Carlo (MC) algorithms and Linear Boltzmann Transport Equation (LBTE) algorithms. The impact of penumbra modeling on OAR dose was assessed with the adjustment of MC modeling parameters and the clinical relevance of the audit cases was explored with a planning study of spine and head and neck (H&N) patient cases. METHODS: Dosimetric audits performed by the Australian Clinical Dosimetry Service (ACDS) of 43 anthropomorphic spine plans and 1318 C-shaped target plans compared the planned dose to doses measured with ion chamber, microdiamond, film, and ion chamber array. An MC EGSnrc model was created to simulate the C-shape target case. The electron cut-off energy Ecut(kinetic) was set at 500, 200, and 10 keV, and differences between 1 and 3 mm voxel were calculated. A planning study with 10 patient stereotactic body radiotherapy (SBRT) spine plans and 10 patient H&N plans was calculated in both Acuros XB (AXB) v15.6.06 and Anisotropic Analytical Algorithm (AAA) v15.6.06. The patient contour was overridden to water as only the penumbral differences between the two different algorithms were under investigation. RESULTS: The dosimetry audit results show that for the SBRT spine case, plans calculated in AXB are colder than what is measured in the spinal cord by 5%-10%. This was also observed for other audit cases where a C-shape target is wrapped around an OAR where the plans were colder by 3%-10%. Plans calculated with Monaco MC were colder than measurements by approximately 7% with the OAR surround by a C-shape target, but these differences were not noted in the SBRT spine case. Results from the clinical patient plans showed that the AXB was on average 7.4% colder than AAA when comparing the minimum dose in the spinal cord OAR. This average difference between AXB and AAA reduced to 4.5% when using the more clinically relevant metric of maximum dose in the spinal cord. For the H&N plans, AXB was cooler on average than AAA in the spinal cord OAR (1.1%), left parotid (1.7%), and right parotid (2.3%). The EGSnrc investigation also noted similar, but smaller differences. The beam penumbra modeled by Ecut(kinetic) = 500 keV was steeper than the beam penumbra modeled by Ecut(kinetic) = 10 keV as the full scatter is not accounted for, which resulted in less dose being calculated in a central OAR region where the penumbra contributes much of the dose. The dose difference when using 2.5 mm voxels of the center of the OAR between 500 and 10 keV was 3%, reducing to 1% between 200 and 10 keV. CONCLUSIONS: Lack of full penumbral modeling due to approximations in the algorithms in MC based or LBTE algorithms are a contributing factor as to why these algorithms under-predict the dose to OAR when the treatment volume is wrapped around the OAR. The penumbra modeling approximations also contribute to AXB plans predicting colder doses than AAA in areas that are in the vicinity of beam penumbra. This effect is magnified in regions where there are many beam penumbras, for example in the spinal cord for spine SBRT cases.
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- 2021
49. Quantifying the impact of SpaceOAR hydrogel on inter‐fractional rectal and bladder dose during 0.35 T MR‐guided prostate adaptive radiotherapy
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Bilal Chughtai, Shu Ling Chen, Sean S. Mahase, Josephine Kang, Reza Farjam, Ryan Fecteau, J. Keith Dewyngaert, Ryan T. Pennell, Madeline Coonce, Himanshu Nagar, and Silvia Ch Formenti
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Male ,Organs at Risk ,Urinary Bladder ,Rectum ,Radiosurgery ,Dose constraints ,Prostate cancer ,Prostate ,medicine ,Humans ,Radiation Oncology Physics ,Radiology, Nuclear Medicine and imaging ,In patient ,Adaptive radiotherapy ,Instrumentation ,Radiation ,business.industry ,Radiotherapy Planning, Computer-Assisted ,Prostatic Neoplasms ,Hydrogels ,Radiotherapy Dosage ,medicine.disease ,Magnetic Resonance Imaging ,medicine.anatomical_structure ,adaptive radiotherapy ,Total dose ,SpaceOAR ,0.35 T MRI‐Linac ,Nuclear medicine ,business ,Mri guided - Abstract
Purpose To investigate the impact of rectal spacing on inter‐fractional rectal and bladder dose and the need for adaptive planning in prostate cancer patients undergoing SBRT with a 0.35 T MRI‐Linac. Materials and Methods We evaluated and compared SBRT plans from prostate cancer patients with and without rectal spacer who underwent treatment on a 0.35 T MRI‐Linac. Each group consisted of 10 randomly selected patients that received prostate SBRT to a total dose of 36.25 Gy in five fractions. Dosimetric differences in planned and delivered rectal and bladder dose and the number of fractions violating OAR constraints were quantified. We also assessed whether adaptive planning was needed to meet constraints for each fraction. Results On average, rectal spacing reduced the maximum dose delivered to the rectum by more than 8 Gy (p
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- 2021
50. Automated treatment planning of prostate stereotactic body radiotherapy with focal boosting on a fast‐rotating O‐ring linac: Plan quality comparison with C‐arm linacs
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Tom Depuydt, Cédric Draulans, Karin Haustermans, Kenneth Poels, Wouter Crijns, Bertrand Dewit, and Robin De Roover
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Male ,GLEASON SCORE ,medicine.medical_specialty ,O‐ring linac ,Boosting (machine learning) ,Computer science ,ONLINE ,GUIDELINES ,Radiosurgery ,TOXICITY ,Linear particle accelerator ,FAILURES ,Prostate ,RADIATION-THERAPY ,medicine ,DISTRIBUTIONS ,Humans ,Radiation Oncology Physics ,Dosimetry ,Radiology, Nuclear Medicine and imaging ,Medical physics ,Adaptive radiotherapy ,Radiation treatment planning ,Instrumentation ,automation ,Science & Technology ,SBRT ,Radiation ,COMPLICATION PROBABILITY ,Radiotherapy Planning, Computer-Assisted ,Radiology, Nuclear Medicine & Medical Imaging ,Truebeam ,Radiotherapy Dosage ,plan quality ,prostate cancer ,CANCER ,DELINEATION ,medicine.anatomical_structure ,focal boost ,O-ring linac ,Radiotherapy, Intensity-Modulated ,Life Sciences & Biomedicine ,Stereotactic body radiotherapy - Abstract
PURPOSE: The integration of auto-segmentation and automated treatment planning methods on a fast-rotating O-ring linac may improve the time efficiency of online adaptive radiotherapy workflows. This study investigates whether automated treatment planning of prostate SBRT with focal boosting on the O-ring linac could generate plans that are of similar quality as those obtained through manual planning on clinical C-arm linacs. METHODS: For 20 men with prostate cancer, reference treatment plans were generated on a TrueBeam STx C-arm linac with HD120 MLC and a TrueBeam C-arm linac with Millennium 120 MLC using 6 MV flattened dual arc VMAT. Manual planning on the Halcyon fast-rotating O-ring linac was performed using 6 MV FFF dual arc VMAT (HA2-DL10) and triple arc VMAT (HA3-DL10) to investigate the performance of the dual-layer MLC system. Automated planning was performed for triple arc VMAT on the Halcyon linac (ET3-DL10) using the automated planning algorithms of Ethos Treatment Planning. The prescribed dose was 35 Gy to the prostate and 30 Gy to the seminal vesicles in five fractions. The iso-toxic focal boost to the intraprostatic tumor nodule(s) was aimed to receive up to 50 Gy. Plan deliverability was verified using portal image dosimetry measurements. RESULTS: Compared to the C-arm linacs, ET3-DL10 shows increased seminal vesicles PTV coverage (D99% ) and reduced high-dose spillage to the bladder (V37Gy ) and urethra (D0.035cc ) but this came at the cost of increased high-dose spillage to the rectum (V38Gy ) and a higher intermediate dose spillage (D2cm). No statistically significant differences were found when benchmarking HA2-DL10 and HA3-DL10 with the C-arm linacs. All plans passed the patient-specific QA tolerance limit. CONCLUSIONS: Automated planning of prostate SBRT with focal boosting on the fast-rotating O-ring linac is feasible and achieves similar plan quality as those obtained on clinical C-arm linacs using manual planning. ispartof: Journal Of Applied Clinical Medical Physics vol:22 issue:9 ispartof: location:United States status: Published online
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- 2021
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