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Chordoid meningioma is a rare, more aggressive subtype of meningioma. This study documents the histological, radiological and clinical features of seven tumours in five patients among 131 meningioma patients who were treated in the Department of Neurosurgery at Istanbul Medipol University between 2014 and 2019. There were two males and three females. All tumours were supratentorial. Surgical Simpson grade II resection was achieved in two cases, grade I in one and grade IV in two. One case relapsed and underwent further surgeries and adjuvant treatment. The chances of survival without recurrence after the Simpson grade I-II resection are high but close follow-up is recommended particularly if grade I cannot be achieved.

We aimed to study the long-term efficacy, prognostic factors and complications associated with the GKRS for trigeminal neuralgia.Prospectively created database was analyzed for these patients. We created an Artificial neural Network - using Multilayer perceptron model in SPSS 23 by including all variables whose p value were0.5 in univariate analysis.A total of 36 patients were included in the study. Patients pain free at 6 months were 25(69.44%), which reduced to 6(40 %) at 6 years. Median time to pain relief was 18.5 days. Only 5(13.88%) of them developed new onset or worsened numbness post Gamma Knife radio surgery. Median radiation dose was 80 Gy (prescribed at 100 percent isodose line). 1st GKT (P value 0.05) and post GKT numbness (P value 0.05) were the only factors favouring good outcome. Prior history of MVD was associated with poor pain relief post GKRS although p value was not significant (p = 0.136). ANN model could predict with 90.0 percent accuracy the favourable or unfavourable response on 11 Tested cases. In ANN model, a greater number of Pre GKT medications, previous MVD history, V2 dermatome involvement and negative history of post GKT numbness were negative prognostic factors.Lesser number of pre GKRS drugs used, involvement of V1 dermatome, post GKT numbness are favourable prognostic factors. Also, history of failed MVD for trigeminal neuralgia is associated with poor outcome. Repeat GKRS failed to show improvement in BNI grades.

Introduction: Gangliogliomas (GG) are considered WHO grade I rare tumors. While they commonly manifest as temporal lobe epilepsy, they can be located anywhere in the brain. Primary treatment is complete microsurgical resection. Remnant or recurrent GG can benefit from radiation therapy. Here, we present a series of GG who received Gamma Knife radiosurgery (GKR) after initial microsurgery. Methods: Between October 2009 and February 2020, four patients benefitted from such approach. The median age at surgery was 16 years (mean 17, 11-25) and at the time of GKR was 22.5 years (mean 23, 19-28). Initial clinical symptom was epilepsy in 3 cases and incidental in one. Biopsy was firstly performed in one case. One patient had stereotactic electroencephalography. The respective anatomical locations were right parieto-occipital, sylvian, left paraventricular and left inferior parietal. Results: Gamma Knife radiosurgery was performed after a median time of 3.5 years after initial gross total microsurgical resection (GTR). The median follow-up after GKR was 54 months (mean 58.5, 6-120). The median marginal dose was 18 Gy (mean 17.5, 16-18). The median target volume was 0.5 mL (mean 0.904, 0.228-2.3). The median prescription isodose volume was 0.6 mL (mean 0.9, 0.3-2.4). At last follow-up, GG majorly decreased in 3 patients, remained stable in one. Conclusion: Gamma Knife radiosurgery is safe and effective for remnant GG after GTR. Primary treatment remains microsurgical resection, especially in cases with symptomatic mass effect or with epilepsy. Single fraction GKR can be a valuable option for remnant or recurrent tumors after initial resection. (C) 2021 The Author(s). Published by Elsevier Ltd.

ZusammenfassungWir berichten über einen Fall, bei dem makroskopische und mikroskopische Veränderungen des Verstibularnervs nach radiochirurgischer Behandlung eines intrameatalen Vestibularisschwannoms beobachtet wurden. Der Fallbericht zeigt das erste Mal ein morphologisches Korrelat der unerwünschten Effekte der Gamma-Knife-Therapie von Vestibularisschwannomen und unterstreicht, dass trotz eines deutlichen Abstands zum bestehenden Tumor degenerative Veränderungen der neuralen Strukturen erwartet werden können.

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.

Vestibular schwannomas (VSs) are benign, slow-growing tumors. Management options include observation, surgery, and radiation. In this retrospective trial, we aimed at evaluating whether biologically effective dose (BED) plays a role in tumor volume changes after single-fraction first intention stereotactic radiosurgery (SRS) for VS. We compiled a single-institution experience (n = 159, Lausanne University Hospital, Switzerland). The indication for SRS was decided after multidisciplinary discussion. Only cases with minimum 3 years follow-up were included. The Koos grading, a reliable method for tumor classification was used. Radiosurgery was performed using Gamma Knife (GK) and a uniform marginal prescription dose of 12 Gy. Mean BED was 66.3 Gy (standard deviation 3.8, range 54.1–73.9). The mean follow-up period was 5.1 years (standard deviation 1.7, range 3–9.2). The primary outcome was changes in 3D volumes after SRS as function of BED and of integral dose received by the VS. Random-effect linear regression model showed that tumor volume significantly and linearly decreased over time with higher BED (p p

Purpose/objectives To report our dosimetric analysis of the hippocampi (HC) and the incidence of perihippocampal tumor location in patients with ≥25 brain metastases who received stereotactic radiosurgery (SRS) in single or multiple sessions. Materials/methods Analysis of our prospective registry identified 89 patients treated with SRS for ≥25 brain metastases. HC avoidance regions (HA-region) were created on treatment planning MRIs by 5 mm expansion of HC. Doses from each session were summed to calculate HC dose. The distribution of metastases relative to the HA-region and the HC was analyzed. Results Median number of tumors irradiated per patient was 33 (range 25–116) in a median of 3 (range 1–12) sessions. Median bilateral HC Dmin (D100), D40, D50, Dmax, and Dmean (Gy) was 1.88, 3.94, 3.62, 16.6, and 3.97 for all patients, and 1.43, 2.99, 2.88, 5.64, and 3.07 for patients with tumors outside the HA-region. Multivariate linear regression showed that the median HC D40, D50, and Dmin were significantly correlated with the tumor number and tumor volume (p Conclusions Hippocampal dose is higher in patients with tumors in the HA-region; however, even for patients with a high burden of intracranial disease and tumors located in the HA-regions, SRS affords hippocampal sparing. This is particularly relevant in light of our finding of eventual perihippocampal metastases in more than half of our patients.

The impact of selection of prescription isodose line (IDL) on plan quality has not been well evaluated during inverse planning (IP). In this study, a total of 180 IP plans at five levels of IDL were generated for 30 brain metastases (BMs). For each BM, one round of IP was performed with typical IP settings, followed by a quick fine‐tuning to ensure the same target coverage and comparable conformality index. The impact of the IDL on the quality metrics (selectivity, gradient index [GI], and treatment time) was evaluated. The decrease of selectivity and increase of GI meant inferior target dose conformality and more dose spillage. Additionally, a metric directly correlated to the treatment time was proposed. For all cases, the mean GI decreased monotonically as IDL decreased from 70% to 30%, and the decreasing rate was significantly different based on tumor size. The mean selectivity and number of shots decreased monotonically as IDL decreased for all the tumors. From 70% to 30% IDL, the decreasing rate of the mean selectivity was 2.8% (p = 0.020), 7.7% (p = 0.005), and 15.4% (p = 0.020) and that of the number of shots was 75.4% (p = 0.001), 73.2% (p = 0.001), and 50.7% (p = 0.009), for the large, medium, and small tumors, respectively. For the medium and small tumor groups, the mean treatment time increased monotonically when IDLs decreased (increasing rate was 80.0% [p = 0.002] for medium tumors [p = 0.001] and 130.8% [p = 0.001] for small tumors from 70% to 30%). For the large tumors, the mean treatment time was the shortest at 50% IDL (59.0 min) and higher at 70% (65.9 min) and 30% (71.9 min). Overall, the GammaPlan chose smaller sectors for plans with lower IDLs except for the large size group.

Tikslas. Tyrimo tikslas įvertinti gama peilio talamotomijos efektyvumą, stabdant tremorą sergantiesiems Parkinsono liga (PL) ir esencialiniu tremoru, kai kiti invaziniai gydymo metodai nerekomenduotini. Tiriamieji ir tyrimo metodai. Nuo 2019 m. birželio iki 2021 m. sausio dėl esencialinio tremoro ir PL sąlygoto tremoro atitinkamai atlikta 27 ir 20 vienpusių gama peilio talamotomijų. Naudojant Leksell G stereotaksinį rėmą, pagal standartizuotą metodiką, naudojant 4 mm diametro kolimatoriaus šūvį, į n.ventralis intermedius (VIM) zoną paskirta 130-140 Gy dozė. Tyrime pooperacinis vertinimas planuotas atlikti praėjus 6 ir 12 mėnesių po taikyto gydymo. Tačiau dėl besikartojančio karantino dėl COVID-19 buvo apsunkintas ligonių kontaktinis vertinimas, todėl rezultatai vertinti telefoninės apklausos metu. Iš 20 ligonių, sergančių PL, pavyko susisiekti tik su 12, iš kurių aštuoniems gydymas buvo taikytas mažiau nei prieš 6 mėnesius. Nuspręsta PL grupės ligonių gydymo rezultatų analizę atlikti po 6 mėnesių. Rezultatai. Iš 27 sergančiųjų esencialiniu tremoru telefonu pakalbinti pavyko 23 ligonius. Viena ligonė per stebėjimo laikotarpį mirė nuo COVID-19 infekcijos. Iš apklaustų 22 ligonių 16 (72 %) teigė, kad jaučia žymų tremoro rankoje sumažėjimą ar visišką jo išnykimą priešingoje, nei atlikta VIM talamotomija, pusėje. Likę 6 ligoniai (28 %) taikyto gydymo efekto iki šiol ne-jaučia. Iš 22 ligonių 4 (18 %) teigė, kad kurį laiką buvo sutrikusi koordinacija ir vargino laikinas rankos nevikrumas, kuris praėjo per kelis mėnesius. Išvados. Gama peilio talamotomija yra saugi ir efektyvi esencialinio rankų tremoro mažinimo priemonė. Pagrindiniai šio gydymo trūkumai yra kelis ar keliolika mėnesių trunkantis latencinis periodas iki pastebimo klinikinio efekto ir laikina ataksija.

Highlights • SRS has emerged as an alternative to WBRT for surgically resected brain metastases. • Pre-therapy radiomic features are predictive of local control after cavity SRS. • Radiomic features were superior to clinical features for predicting local control., Purpose Adjuvant radiosurgery to the cavities of surgically resected brain metastases provides excellent local tumor control while reducing the risk of deleterious cognitive decline associated with whole brain radiotherapy. A subset of these patients, however, will develop disease recurrence following radiosurgery. In this study, we sought to assess the predictive capability of radiomic-based models, as compared with standard clinical features, in predicting local tumor control. Methods We performed a retrospective chart review of patients treated with adjuvant radiosurgery for resected brain metastases at the “Institution” from 2009 to 2019. Shape, intensity and texture based radiomics features of the cavities were extracted from the pre-radiosurgery treatment planning MRI scans and trained using a gradient boosting technique with K-fold cross validation. Results In total, 71 cavities from 67 treated patients were included for analysis. The 6 and 12 month local control estimates were 86% and 76%, respectively. The 6 and 12 month overall survival was 78% and 55%, respectively. Thirty-six patients developed intracranial failures outside of the surgical cavity. The predictive model for local control trained on imaging features from the whole cavity achieved an area-under-the-curve (AUC) of 0.73 on the validation set versus an AUC of 0.40 for the clinical features. Conclusions Here we report a single institutional experience using radiomic-based predictive modeling of local tumor control following adjuvant Gamma Knife radiosurgery for resected brain metastases. We found the radiomics features to provide more robust predictive models of local control rates versus clinical features alone. Such techniques could potentially prove useful in the clinical setting and warrant further investigation.

Brain tumors, which are among the most common solid tumors in childhood, remain a leading cause of cancer-related mortality in pediatric population. Gliomas, which may be broadly categorized as low grade glioma and high grade glioma, account for the majority of brain tumors in children. Expectant management, surgery, radiation therapy (RT), chemotherapy, targeted therapy or combinations of these modalities may be used for management of pediatric gliomas. Several patient, tumor and treatment-related characteristics including age, lesion size, grade, location, phenotypic and genotypic features, symptomatology, predicted outcomes and toxicity profile of available therapeutic options should be considered in decision making for optimal treatment. Management of pediatric gliomas poses a formidable challenge to the physicians due to concerns about treatment induced toxicity. Adverse effects of therapy may include neurological deficits, hemiparesis, dysphagia, ataxia, spasticity, endocrine sequelae, neurocognitive and communication impairment, deterioration in quality of life, adverse socioeconomic consequences, and secondary cancers. Nevertheless, improved understanding of molecular pathology and technological advancements may pave the way for progress in management of pediatric glial neoplasms. Multidisciplinary management with close collaboration of disciplines including pediatric oncology, surgery, and radiation oncology is warranted to achieve optimal therapeutic outcomes. In the context of RT, stereotactic irradiation is a viable treatment modality for several central nervous system disorders and brain tumors. Considering the importance of minimizing adverse effects of irradiation, radiosurgery has attracted great attention for clinical applications in both adults and children. Radiosurgical applications offer great potential for improving the toxicity profile of radiation delivery by focused and precise targeting of well-defined tumors under stereotactic immobilization and image guidance. Herein, we provide a concise review of stereotactic irradiation for pediatric glial neoplasms in light of the literature.

Arteriovenous malformations (AVM) are quite rare, but they are dangerous pathology due to the risk of rupture and intracranial hemorrhage, which leads to disability. This review enlights the epidemiology of AVM and their symptoms, current methods of diagnostics and treatment as well as prognosis and treatment outcomes. Nowadays microsurgical removal, endovascular embolization, stereotactic radiosurgery and combination of these methods are used in clinical practice for AVMs treatment. Stereotactic radiosurgery is a highly effective non-invasive technique resulting in high degree of AVM obliteration with low risk of complications. The results of magnetic resonance imaging usage in assessing the degree of obliteration and the development of post-radiation complications are presented in this article. The optimization of magnetic resonance imaging algorithm is necessary for determination of statistically significant factors affecting the obliteration process.

Purpose To determine the targeting accuracy of brain radiosurgery when planning procedures employing different MRI and MRI + CT combinations are adopted. Materials and method A new phantom, the BrainTool, has been designed and realized to test image co-registration and targeting accuracy in a realistic anatomical situation. The phantom was created with a 3D printer and materials that mimic realistic brain MRI and CT contrast using a model extracted from a synthetic MRI study of a human brain. Eight markers distributed within the BrainTool provide for assessment of the accuracy of image registrations while two cavities that host an ionization chamber are used to perform targeting accuracy measurements with an iterative cross-scan method. Two procedures employing 1.5 T MRI-only or a combination of MRI (taken with 1.5 T or 3 T scanners) and CT to carry out Gamma Knife treatments were investigated. As distortions can impact targeting accuracy, MR images were preliminary evaluated to assess image deformation extent using GammaTool phantom. Results MR images taken with both scanners showed average and maximum distortion of 0.3 mm and 1 mm respectively. The marker distances in co-registered images resulted below 0.5 mm for both MRI scans. The targeting mismatches obtained were 0.8 mm, 1.0 mm and 1.2 mm for MRI-only and MRI + CT (1,5T and 3 T), respectively. Conclusions Procedures using a combination of MR and CT images provide targeting accuracies comparable to those of MRI-only procedures. The BrainTool proved to be a suitable tool for carrying out co-registration and targeting accuracy of Gamma Knife brain radiosurgery treatments.

Gamma knife radiosurgery (GKRS) is an established treatment option for residual and recurrent nonfunctioning pituitary adenoma (NFPA). This investigation assessed hormonal and radiologic outcomes after adjuvant and primary GKRS for NFPAs.This retrospective study included 252 patients with NFPA who underwent GKRS at a single center between 2005 and 2016. GKRS was performed as adjuvant procedure in 216 (85.8%) patients and as primary procedure in 36 (14.2%) patients. Characteristics of these two groups were compared.Mean age was comparable between adjuvant and primary GKRS groups (48.3 ± 12.6 vs. 52.2 ± 13.2 years, respectively,GKRS was effective both as adjuvant and primary procedure in patients with NFPA. Radiation dose of ≤13.5 Gy was associated with lower tumor control rate and tumor volume5 cm

With the advent of minimally invasive neurosurgical techniques and rapid innovations in the field of neurointervention, there has been a sharp rise in diagnostic and therapeutic modalities requiring radiation exposure. Neuroanesthesiologists are currently involved in various procedures inside as well as outside the operating room (OR) like intensive care units, interventional suites, and gamma knife units. The ambit expands from short-lasting diagnostic scans to lengthy therapeutic procedures performed under fluoroscopic guidance. Hence, a modern-day neuroanesthesiologist has to bear the brunt of the radiation exposure in both inside and outside the OR. However, obliviousness and nonadherence to the relevant radiation safety measures are still prevalent. Radiation protection and safety are topics that need to be discussed with new vigor in the light of current practice.

Objective With the development of interventional therapy and precise radiotherapy, such as 3‐D conformal intensity‐modulated radiation therapy and stereotactic body radiotherapy (SBRT), transarterial chemoembolization (TACE) combined with radiotherapy has become an important method of comprehensive treatment for advanced liver cancer. However, few studies focus on the treatment of massive hepatocellular carcinoma (HCC) with SBRT. In this study, we investigated the effects and prognostic factors of whole‐body gamma‐knife SBRT combined with TACE in the treatment of massive HCC. Methods A retrospective analysis was carried out in 81 patients with massive, who received super gamma‐knife (type SGS‐I) SBRT after TACE treatment between 2 January 2011 and 30 June 2016. The curative effects were evaluated using the Modified Response Evaluation Criteria in Solid Tumors criteria. The alpha‐fetoprotein and alanine aminotransferase levels were measured before and after treatment. Patients were followed up for overall survival and 1‐, 3‐, and 5‐year survival rates. Adverse reactions were evaluated using the Radiation Therapy Oncology Group and the European Organization for Research and Treatment of Cancer criteria. Results A total of 81 patients were evaluated, including 29 patients with complete response, 48 patients with partial response, two patients with stable disease, and two patients with progressive disease; the total response rate was 95.06%. The 1‐year local control rate was 71.60%. The overall survival rates at 1, 3, and 5 years were 81.48%, 40.74%, and 16.67%, respectively. The median survival time was 15.0 months (95% CI 10.1–19.8 months). Progression‐free time was 11.0 months (95% CI 9.5–14.4 months). The alpha‐fetoprotein level after treatment was (85.53 ± 21.36) μg/L and was significantly lower than that before treatment (635.62 ± 125.83 μg/L; t = 8.189, P = 0.002). The alanine aminotransferase levels were 70.34 ± 16.60 and (54.95 ± 12.02) U/L before and after treatment, respectively, and were not significantly different (t = 1.348, P = 0.624). Multivariate analysis showed that a portal vein tumor thrombus (χ2 = 4.727, P = 0.016) and the Child–Pugh grade of liver function (χ2 = 4.893, P = 0.013) were adverse prognostic factors of overall survival. The 1‐year local control rates and the median survival times were 72.03% and 71.17%, and 16 and14 months, respectively, for the clinical target volumes ≥120 cm3 and

BackgroundFocused ultrasound (FUS) was approved as a new treatment modality for essential tremor (ET) in 2016. The goal of this study was to quantify FUS adoption for ET and understand its drivers.MethodsThe adoption of the various surgical options for ET was estimated using three measures: the number of presentations on the various surgical treatments for ET at specialised international meetings, the number of original papers published as identified by literature searches and the number of thalamotomy procedures performed worldwide for ET as provided by device manufacturers’ registries.ResultsFirst, we found that the number of presentations related to lesioning procedures is increasing relative to deep brain stimulation (DBS) at international meetings. Second, there are already more publications on FUS (93) than stereotactic radiosurgery (SRS) (68) or radiofrequency (43) for ET, although they still lag behind DBS papers (750). Third, the number of annual FUS thalamotomies performed for ET (n>1200 in 2019) in 44 centres has surpassed the annual procedures across 342 Gamma Knife units (nConclusionFUS is being rapidly adopted for the treatment of ET. We hypothesise that its perceived minimally invasive nature coupled with the ability to perform intraoperative clinical assessments, its immediate effects and active marketing efforts are contributing factors. As lesioning modalities for the treatment of ET are reappraised, the superior popularity of FUS over SRS appears to arise for reasons other than differences in clinical outcomes.

The treatment of patients with ≥11 brain metastases (BMs) with stereotactic radiosurgery (SRS) alone has yet to be established. The aim of this study was to compare results of SRS alone in patients with 5-10 BMs versus 11-20 BMs.This was an institutional review board-approved, retrospective cohort study using our prospectively accumulated database including 1515 patients with 5-10 tumors and 804 patients with 11-20 tumors treated with Gamma Knife SRS by 2 experienced neurosurgeons between 1998 and 2018. The Kaplan-Meier method was applied to determine post-SRS survival times, and competing risk analyses were used to estimate cumulative incidences of the secondary end points.The post-SRS median survival time was slightly longer in the group with 5-10 tumors (7.7 months) than in the group with 11-20 tumors (6.5 months) (P0.0001). Median survival time differences were statistically significant for patients with lung cancers but not for patients with breast, gastrointestinal tract, kidney, and other cancers. Multivariable analysis revealed female sex, better Karnofsky performance scale score, controlled primary cancer, and absence of extracerebral metastases to be statistically significant predictors of longer survival in the 2 patient cohorts. Crude and cumulative incidences of local recurrences were significantly lower in the group with 11-20 tumors than in the group with 5-10 tumors, while those of other secondary end points were similar to or lower in the group with 11-20 tumors than in the group with 5-10 tumors. Post-SRS outcomes were relatively poor in patients with 11-20 tumors from kidney or other cancers.Carefully selected patients with 11-20 BMs are not unfavorable candidates for SRS alone.

Stereotactic radiosurgery (SRS) was born in an attempt to treat complex intracranial pathologies in a fashion whereby open surgery would create unnecessary or excessive risk. To create this innovation, it was necessary to harness advances in other fields such as engineering, physics, radiology, and computer science. We review the history of SRS to provide context to today’s current state, as well as guide future advancement in the field. Since time of Lars Leksell, the young Swedish neurosurgeon who pioneered the development of the SRS, the collegial and essential partnership between neurosurgeons, radiation oncologists and physicists has given rise to radiosurgery as a prominent and successful tool in neurosurgical practice. We examine how neurosurgeons have helped foster the SRS evolution and how this evolution has impacted neurosurgical practice as well as that of radiation oncology and neuro-oncology.

Introduction: Supratentorial primitive neuroectodermal tumor is a rare, aggressive intrinsic brain tumor with limited treatment options for recurrent disease. SRS as a treatment modality in the recurrent setting was investigated. Methods: A retrospective review of 8 patients treated with SRS for local or distant recurrence of supratentorial PNET from 1999 to 2014 was conducted. Results: Thirty-six tumors were treated in 15 sessions in 8 patients. The median patient age was 22.5 (interquartile range [IQR], 14.75–43.5 years) with a median 21-month period from diagnosis until SRS (IQR, 16–23.75 months). The median prescription isodose volume was 1.85 cm3 (IQR, 1.85–7.02 cm3); median tumor margin dose was 18 Gy (IQR 14–20 Gy); and median isocenters was 2 (range 1–13). No patients experienced adverse radiation effects. All but 1 patient died, and the median overall survival was 32 months (IQR, 26.75–53.5 months) with median overall survival following SRS of 9.5 months (IQR, 5.25–30 months). Univariate analysis failed to demonstrate a statistically significant association between age, number of gamma knife treatments, interval to gamma knife, and margin radiation dose with overall survival. Discussion/Conclusion: This series supports the use of SRS in patients with recurrent supratentorial PNET following multimodal therapy.

Objective High precision and accuracy are expected in gamma knife radiosurgery treatment. Because of the requirement of clinically applying complex radiation and dose gradients together with a rapid radiation decline, a dedicated quality assurance program is required to maintain the radiation dosimetry and geometric accuracy and to reduce all associated risk factors. This study investigates the validity of Leksell Gamma plan (LGP)10.1.1 system of 5th generation Gamma Knife Perfexion as modified variable ellipsoid modeling technique (VEMT) method. Methods To verify LGP10.1.1 system, we compare the treatment plan program system of the Gamma Knife Perfexion, that is, the LGP, with the calculated value of the proposed modified VEMT program. To verify a modified VEMT method, we compare the distributions of the dose of Gamma Knife Perfexion measured by Gafchromic EBT3 and EBT-XD films. For verification, the center of an 80 mm radius solid water phantom is placed in the center of all sectors positioned at 16 mm, 4 mm and 8 mm; that is, the dose distribution is similar to the method used in the x, y, and z directions by the VEMT. The dose distribution in the axial direction is compared and analyzed based on Full-Width-of-Half-Maximum (FWHM) evaluation. Results The dose profile distribution was evaluated by FWHM, and it showed an average difference of 0.104 mm for the LGP value and 0.130 mm for the EBT-XD film. Conclusion The modified VEMT yielded consistent results in the two processes. The use of the modified VEMT as a verification tool can enable the system to stably test and operate the Gamma Knife Perfexion treatment planning system.

Objective: The aims of this study were to investigate the incidence, risk factors and prognosis of pituitary hemorrhage in pituitary adenomas treated with gamma knife radiosurgery (GKRS). Methods and materials: Between December 1993 and December 2016, 751 consecutive pituitary adenoma patients treated with GKRS were retrospectively reviewed in a single center. There were 271 male (36.1%) and 480 female (63.9%) patients with a median age of 38.5 (range, 7.2-84.0) years. The number of nonfunctioning pituitary adenomas (NFPAs) and functioning pituitary adenomas were 369 (49.1%) and 382 (50.9%) respectively. The median follow-up time was 61.1 (range, 12.1-304.4) months. Results: In this study, 88 patients (11.7%) were diagnosed with pituitary hemorrhage before GKRS, 55 patients (7.3%) developed new or worsened pituitary hemorrhage after GKRS (excluding 3 patients with new or worsened pituitary hemorrhage due to tumor regrowth). The median time to new or worsened pituitary hemorrhage after GKRS was 18.9 (range 3.1-70.7) months. Overall, 128 patients (17.0%) were diagnosed with pituitary hemorrhage in the entire series. After adjustment with logistic regression, nonfunctioning pituitary adenomas (NFPAs) (odds ratio [OR]=2.121, 95% confidence interval [CI]=1.195-3.763, p=0.010) and suprasellar extension (OR=2.470, 95% CI=1.361-4.482, p=0.003) were associated with pituitary hemorrhage before GKRS. NFPA (OR=3.271, 95% CI=1.278-8.373, p=0.013) was associated with new or worsened pituitary hemorrhage after GKRS. Five patients received surgical resection for new or worsened pituitary hemorrhage were considered as GKRS treatment failure. Two patients with new hypopituitarism were considered to be owed to new or worsened pituitary hemorrhage after GKRS. Conclusions: New or worsened pituitary hemorrhage after GKRS was not an uncommon phenomenon. NFPA was an independent risk factor of new or worsened pituitary hemorrhage after GKRS. New or worsened pituitary hemorrhage after GKRS could lead to GKRS treatment failure. GKRS might be a precipitating factor of pituitary hemorrhage.

A series of 3 patients (35–60 years old) with bleeding distal aneurysm not associated with AVM who underwent radiosurgery by gamma knife are reported. One isocentre centralized over the aneurysm was used; peripheral dose 24–28.8 Gy was applied. Control angiography 20–36 months after gamma knife surgery (GKS) demonstrated obliteration of both the aneurysm and the feeding artery, without deterioration of the neurological symptoms. Our case series implies that GKS might serve as a safe mini-invasive technique in the treatment of selected distal aneurysms.

Background Choroid plexus tumors (CPT) are rare epithelial tumors of the choroid plexus. Gross total resection (GTR) may be curative, but it is not always possible. Objective To evaluate the role of Gamma Knife stereotactic radiosurgery (GKSRS) as either a primary or adjuvant management option for WHO grade I-III CPT through a multicenter project. Methods A total of 32 patients (20 females) with a total of 43 treated tumors were included in the analysis. A total of 25 patients (78%) had undergone initial surgical resection. The median total tumor volume was 2.2 cc, and the median margin and maximum doses were 13 and 25.5 Gy, respectively. Results Local tumor control was achieved in 69% of cases. Local tumor progression-free survival (PFS) rate for low-grade tumors at 1, 3, and 5 yr was 90%, 77%, 58%, respectively. The actuarial local tumor PFS rate for high-grade tumors at 1, 3, and 5 yr was 77%, 62%, and 62%, respectively. There was no significant difference in local tumor control rates between low- and high-grade CPT (P = .3). Gender, age, and degree of resection were not associated with treated tumor PFS. Distant intracranial spread developed in 6 patients at a median of 22 mo after initial SRS. Actuarial distant brain tumor PFS rate at 1, 2, 5, and 10 yr was 93%, 88%, 78%, and 65%, respectively. Three patients (9%) developed persistent symptomatic adverse radiation effects at a median of 11 mo after the procedure. Conclusion GKSRS represents a minimally invasive alternative management strategy for imaging defined or surgically recurrent low- and high-grade CPT.

Background: We proposed an algorithm to automate the components within the identification of components within the nidus of cerebral arteriovenous malformations (AVMs) which may be used to analyze the relationship between its diffuseness and treatment outcomes following stereotactic radiosurgery (SRS). Objectives: to determine the impact of the diffuseness of the AVM nidus on SRS outcomes. Methods: This study conducted regular follow-ups of 209 patients with unruptured AVMs who underwent SRS. The diffuseness of the AVM nidus was estimated by quantifying the proportions of vascular nidal component, brain parenchyma, and cerebrospinal fluid in T2-weighted MRIs. We used Cox regression analysis to characterize the association between nidal diffuseness and treatment outcomes in terms of obliteration rate and radiation-induced change (RICs) rate following SRS. Results: The median AVM volume was 20.7 cm3. The median duration of imaging follow-up was 51 months after SRS. The overall AVM obliteration rate was 68.4%. RICs were identified in 156 of the 209 patients (74.6%). The median proportions of the nidus of AVM and brain parenchyma components within the prescription isodose range were 30.2 and 52.2%, respectively. Cox regression multivariate analysis revealed that the only factor associated with AVM obliteration rate after SRS was AVM volume. However, a larger AVM volume (>20 mL) and a larger proportion of brain parenchyma (>50%) within the prescription isodose range were both correlated with a higher RIC rate following SRS. Conclusions: The diffuseness of the nidus indeed appears to affect the RIC rate following SRS in patients with unruptured AVMs.

Background Management of intracranial Langerhans cell histiocytosis generally includes surgical resection. Case Description A female patient with a diagnosis of Langerhans cell histiocytosis developed multiple brain lesions. As part of her multimodality treatment, she underwent Gamma Knife stereotactic radiosurgery on 4 occasions over a 20-year period. All tumors showed significant shrinkage on serial imaging after initially demonstrating a transient expansion. No permanent postradiosurgery complications occurred. Conclusions As part of multimodality management of this recurrent and refractory disease, Gamma Knife stereotactic radiosurgery should be considered an important salvage option that can control local disease and obviate the need for invasive surgery.

OBJECTIVE Cerebral cavernous malformation (CM) is an angiographically occult vascular pathology. Although microsurgery is the gold standard treatment to control the symptoms of CM, resection carries high risk in some situations, especially eloquent areas. The objective was to evaluate annual hemorrhage rates (AHRs) before and after stereotactic radiosurgery (SRS) treatment of cerebral CM in different locations. METHODS A total of 195 patients (119 women and 76 men) with CM treated at the Gazi University Gamma Knife Center between April 2005 and June 2017 were analyzed. The mean ± SD follow-up period was 67.4 ± 31.1 months (range 12 days to 170 months). AHR before SRS, AHR after SRS, morbidity associated with radiation, seizure control rate after SRS, lesion volume, coexistence with developmental venous anomaly, and SRS treatment parameters were analyzed, with evaluation of radiological data and clinical charts performed retrospectively. The seizure control rate was assessed using the Engel outcome scale. RESULTS The AHR before SRS was 15.3%. Application of SRS to these patients significantly reduced the AHR rates to 2.6% during the first 2 years after treatment and to 1.4% thereafter. Favorable seizure control (Engel class I and II) after radiosurgery was achieved in 23 patients (88.5%) with epilepsy. Radiation-related temporary complications occurred in 15.4% of patients, and permanent morbidity occurred in 4.6%. CONCLUSIONS SRS is a safe and effective treatment modality for reducing the hemorrhage risk of CM. The authors suggest that SRS should be considered for the treatment of patients with CM, high surgical risks, and hemorrhage history, instead of a using a wait-and-see policy.

Purpose The Gamma Knife (GK) Icon allows for the delivery of stereotactic radiosurgery using a thermoplastic mask in combination with intrafraction motion monitoring using high definition motion management. The system pauses treatment if the magnitude of motion in all directions exceeds 1 to 1.5 mm, causing a break in treatment and prolongation of the session. We reviewed the records of patients treated in a frameless manner on our GK Icon system to determine predictors for treatment interruption. Methods and Materials We reviewed the records of patients treated between May 2019 and May 2020 on the GK Icon using a frameless technique for brain metastases, gliomas, schwannomas, and meningiomas. We recorded treatment time as noted in the plan document, actual treatment delivery time, and any pauses in treatment. We tabulated baseline characteristics including age, gender, diagnosis, performance status, and shifts at time of treatment. We used a receiver operating curve analysis to determine a timepoint corresponding with treatment interruption. We then conducted a logistic regression analysis to generate odds ratios for likelihood of treatment. Results We identified 150 patients meeting inclusion criteria. The majority (82%) were patients with brain metastases. The median age was 63 and the median dose was 27 Gy (16-30 Gy) in 3 fractions (1-5 fractions). The median treatment time was 23 minutes (4-108 minutes). Sixty-nine patients (46%) had at least 1 pause in treatment (range, 1-7). Receiver operating curve analysis revealed treatment time >19 minutes and rotation >0.47 degrees to be associated with interruption. Multivariable logistic regression revealed rotation >0.47 degrees and treatment time >19 minutes as predictive of interruption. Conclusions For patients with rotations exceeding 0.47 degrees or an extended treatment time, physicians should expect treatment interruptions, consider fractionation to lessen table time, or use a frame-based approach.

Objective The aim of this study is to determine if pretreatment growth of sporadic vestibular schwannomas (VS) predicts postradiosurgery response. Methods This study was a retrospective chart review at a tertiary referral center of patients with VS that had at least two pretreatment magnetic resonance imaging (MRI) studies at least 6 months apart and underwent Gamma Knife radiosurgery with a minimum of 14 months postradiosurgery imaging surveillance. Tumor linear measurements and volumetric segmentation were assessed before and after radiosurgery. The main outcome measure was persistent enlargement following radiosurgery, defined as 2 mm enlargement in greatest axial diameter or 20% enlargement in volume without size regression. Results Thirty-five patients met the inclusion criteria. Patients were observed for median pre- and posttreatment intervals of 29.5 and 40.6 months, respectively. Median dose to the tumor margin was 13 Gy. Postradiosurgery enlargement occurred in six (17.1%) and nine (25.7%) patients based on linear and volumetric enlargement definitions, respectively. Pseudoprogression—defined as tumor enlargement—followed by linear or volumetric regression that occurred in 34.3% of tumors, reaching a maximum size at a median time of 6.3 months (3.3–8.4) postradiosurgery. When controlling for age, gender, and radiation dose, preradiosurgery tumor volume less than 0.3 cm3 (odds ratio [OR]: 59.7, p = 0.012) and preradiosurgery tumor diameter growth rate greater than or equal to 2.5 mm/year (OR: 19.3, p = 0.045) were associated with persistent postradiosurgery tumor enlargement. Conclusion Smaller pretreatment tumor volume and greater linear tumor growth rates were associated with postradiosurgery tumor enlargement when controlling for age, gender, and radiation dose. Level of Evidence This study indicates that the level of evidence is V.

Background Klippel-Trenaunay-Weber syndrome (KTWS) is characterized by the presence of a combined vascular malformation of capillaries, veins, and lymphatic vessels; congenital venous abnormalities; and limb hypertrophy. Its association with neurovascular abnormalities is infrequent, and the presence of intracranial arteriovenous malformations (AVMs) is extremely rare. Case Description We report a case of a 48-year-old male diagnosed with KTWS who spontaneously presented with a cerebral hemorrhage. Computed tomography scan and angio−computed tomography studies revealed bleeding associated with AVM rupture. In the conventional arteriography study, 10 small ( Conclusions Cerebral AVMs are extremely rare in KTWS cases; however, their presence can have serious consequences if they are treated. We find it advisable to include brain imaging tests, such as nuclear magnetic resonance imaging, to diagnose and monitor KTWS. Furthermore, a Gamma Knife may be useful when multiple AVMs are present.

Purpose To compare planning indices achieved using manual and inverse planning approaches for Gamma Knife radiosurgery of arterio‐venous malformations (AVMs). Methods and materials For a series of consecutive AVM patients, treatment plans were manually created by expert planners using Leksell GammaPlan (LGP). Patients were re‐planned using a new commercially released inverse planning system, IntuitivePlan. Plan quality metrics were calculated for both groups of plans and compared. Results Overall, IntuitivePlan created treatment plans of similar quality to expert planners. For some plan quality metrics statistically significant higher scores were achieved for the inversely generated plans (Coverage 96.8% vs 96.3%, P = 0.027; PCI 0.855 vs 0.824, P = 0.042), but others did not show statistically significant differences (Selectivity 0.884 vs 0.856, P = 0.071; GI 2.85 vs 2.76, P = 0.096; Efficiency Index 47.0% vs 48.1%, P = 0.242; Normal Brain V12(cc) 5.81 vs 5.79, P = 0.497). Automatic inverse planning demonstrated significantly shorter planning times over manual planning (3.79 vs 11.58 min, P

Malignant gliomas consist 15.6 % of all primary brain tumors. Amidst the group of neoplasms, glioblastoma remains the most common primary malignant brain tumor in adults. Mortality of patients with glioblastoma remains the highest among all cancer patients, approaching the absolute. At the present stage, a combined multimodal approach based on adjuvant chemotherapy and radiotherapy after the most safe microsurgical resection of the tumor is considered to be the standard protocol for the treatment of glioblastoma, but the median survival of patients does not exceed 24.5 months. Recently, the role of stereotactic radiosurgery in the treatment of glioblastoma recurrence is increasing, which is due to the high efficiency and organ-preserving specifics of the radiosurgical effect. Our clinic uses stereotactic radiosurgery on the gamma knife, which is a successful combination of surgical and radio-oncological treatment technologies, using a high dose of focused radiation (in one or several procedures) and a sharp drop in the dose, which results in a pronounced radiobiological effect, along with a gentle attitude towards adjacent anatomical structures. As part of this work, a clinical example of long-term survival with a high quality of life is given in the treatment of recurrent glioblastoma on the gamma knife.

Purpose Frameless Gamma Knife stereotactic radiosurgery (SRS) uses a moldable headrest with a thermoplastic mask for patient immobilization. An efficacious headrest is time consuming and difficult to fabricate due to the expertise required to mold the headrest within machine geometrical limitations. The purpose of this study was to design and validate a three‐dimensional (3D)‐printed headrest for frameless Gamma Knife SRS that can overcome these difficulties. Materials and methods A headrest 3D model designed to fit within the frameless adapter was 3D printed. Dosimetric properties of the 3D‐printed headrest and a standard‐of‐care moldable headrest were compared by delivering a Gamma Knife treatment to an anthropomorphic head phantom fitted with an ionization chamber and radiochromic film. Ionization measurements were compared to assess headrest attenuation and a gamma index was calculated to compare the film dose distributions. A volunteer study was conducted to assess the immobilization efficacy of the 3D‐printed headrest compared to the moldable headrest. Five volunteers had their head motion tracked by a surface tracking system while immobilized in each headrest for 20 min. The recorded motion data were used to calculate the average volunteer movement and a paired t‐test was performed. Results The ionization chamber readings were within 0.55% for the 3D‐printed and moldable headrests, and the calculated gamma index showed 98.6% of points within dose difference of 2% and 2 mm distance to agreement for the film measurement. These results demonstrate that the headrests were dosimetrically equivalent within the experimental uncertainties. Average motion (±standard deviation) of the volunteers while immobilized was 1.41 ± 0.43 mm and 1.36 ± 0.51 mm for the 3D‐printed and moldable headrests, respectively. The average observed volunteer motion between headrests was not statistically different, based on a P‐value of 0.466. Conclusions We designed and validated a 3D‐printed headrest for immobilizing patients undergoing frameless Gamma Knife SRS.