Search

In the delivery of stereotactic radiosurgery (SRS) by linear accelerator (LINAC), dynamic conformal arc therapy (DCAT) with non-coplanar beams is conventionally used. However, volumetric modulated arc therapy (VMAT) can improve target conformity, thereby decreasing the dose to organs at risk by inversed planning methods, but few studies have directly compared DCAT and VMAT with and without non-coplanar beams in patients with single brain metastasis. We therefore conducted a planning study to compare the dose distribution in DCAT, VMAT using only a coplanar arc (CoVMAT) and VMAT with non-coplanar arcs (NcVMAT) in the treatment of single brain metastasis. DCAT, CoVMAT and NcVMAT plans were created for 15 patients. The three modalities were compared in terms of target conformity, target coverage, the dose to normal brain tissue, monitor units (MUs) and beam-on time. Both conformity indices (RTOG-CI and IP-CI) as well as the D98% of the gross target volume (GTV) were significantly better in the NcVMAT plans than in the DCAT plans. Comparisons of the doses to normal brain tissue revealed that the V20Gy, V15Gy, V12Gy, V10Gy and V5Gy were significantly smaller in the NcVMAT plans than in the plans based on the other two modalities. The MUs of the DCAT and NcVMAT plans were larger than those of the CoVMAT plans, and the beam-on time was longer in the NcVMAT and CoVMAT plans than in the DCAT plans. Compared to the CoVMAT and DCAT plans, NcVMAT plans significantly improved target conformity and reduced the doses to normal brain tissue at V20Gy, V15Gy, V12Gy, V10Gy and V5Gy.

We applied two propensity score-based analyses to simultaneously compare three treatment modalities—stereotactic body radiotherapy (SBRT), lobectomy, or sublobar resection (SLR)—for stage I non-small cell lung cancer (NSCLC), with the aim of clarifying the average treatment effect (ATE) and formulating a risk-adapted approach to treatment selection. A retrospective review of 823 patients aged ≥65 years who underwent SBRT, lobectomy, or SLR for stage I NSCLC was conducted. The following two analyses using machine learning-based propensity scores were performed: (i) propensity score weighting (PSW) to assess the ATE in the entire cohort, and (ii) propensity score subclassification (PSS) to evaluate treatment effects of subgroups. PSW showed no significant difference in the 5-year overall survival (OS) between SBRT and SLR (60.0% vs 61.2%; P = 0.70) and significant difference between SBRT and lobectomy (60.0% vs 77.6%; P = 0.026). Local (LR) and distant recurrence (DR) rates were significantly lower in lobectomy than in SBRT, whereas there was no significant difference between SBRT and SLR. PSS identified four subgroups with different patient characteristics: lobectomy-oriented (5-year cumulative incidences of non-lung cancer death, 7.5%), SLR-oriented (14.2%), SBRT-oriented (23.8%) and treatment-neutral subgroups (16.1%). Each subgroup showed different survival trends regarding the three treatments. The ATE of SBRT was not significantly different from that of SLR, but it was inferior to lobectomy. Four subgroups with different risks of non-lung cancer death and different survival trends for each treatment were identified. These would help decision-making for patients with stage I NSCLC.

The prognosis of patients with recurrence of uterine cervical cancer after definitive radiotherapy and the efficacy of local salvage therapy for recurrence were evaluated. We retrospectively reviewed 110 patients who were treated with definitive radiotherapy/chemoradiotherapy for uterine cervical cancer between 2008 and 2017 at our institution. Local salvage therapy was defined as any surgery or radiotherapy described in the medical record as intended for local control or cure. We identified 25 patients who developed recurrence after definitive radiotherapy/chemoradiotherapy. The median follow-up time post-recurrence was 18.9 months. Thirteen patients (52%) reported recurrence in the isolated extra-pelvic lymph node (EPLN). The 2-year overall survival after first recurrence (OSr) for patients with isolated EPLN recurrence was 83.1%, compared to that of 31.2% for patients with other patterns of recurrence (p

Purpose To evaluate intrafractional head motion (IFM) in patients who underwent intracranial stereotactic radiosurgery with the ExacTrac X-ray system (ETX) and a frameless mask. Methods A total of 143 patients who completed a pre-treatment examination for IFM were eligible for this study. The frameless mask type B R408 (Klarity Medical & Equipment Co., Ltd., Guangzhou, China), which covers the back of the head, and the entire face, was used for patient immobilization. After the initial 6D correction and first X-ray verification (IFM1), X-ray verification was performed every 3 min for a duration of 15 min. The IFMp (2 ≤ p ≤ 6) was calculated as the positional difference from IFM1. In addition, the inter-phase IFM (IP-IFM) and IFMm were calculated. The IP-IFM was defined as |IFMp − IFMp-1|, and IFMm as the difference between the values after all patients were asked to move their heads intentionally with the frameless mask on. Results Both translational IFMp and IP-IFM exceeded 1 mm for a single patient, whereas, for all patients, the translational IFMm values were kept to within 1 mm in all directions. The proportions of the rotational IFMp, IP-IFM, and IFMm values within 0.5° were greater than 94.4%, 98.6%, and 90.2% for all of the rotational axes, respectively. Conclusions A frameless mask achieved highly accurate patient positioning in combination with ETX and a 6°-of-freedom robotic couch; however, a deviation over 1 mm and 0.5° was observed with low frequency. Therefore, X-ray verification and correction are required during treatment.

To evaluate the displacement of gross tumor volume (GTV) positions caused by intrafractional residual setup errors (RSEs) and to accumulate delivered dose distributions considering intrafraction RSEs in fractionated-stereotactic radiotherapy (f-SRT) with single isocenter volumetric modulated arc therapy (SI-VMAT) for multiple brain metastases.Overall, 72 consecutive patients who underwent f-SRT with SI-VMAT for multiple brain metastases were included. For all patients, 6D correction was performed using the ExacTrac X-ray (ETX) system. GTV displacement (ΔD) was calculated considering the intrafractional RSEs measured by the ETX system during irradiation. The correlation between ΔD and the distance from the isocenter to each GTV (d) was analyzed. Computed tomography (CT) images considering the intrafractional RSEs were generated for five patients with ΔD 1 mm. The delivered dose distributions for all fractions were reconstructed on the corresponding CT, followed by their accumulation.The 95th percentile of ΔD from 7,270 resultant center positions of 417 GTVs was 0.92 mm. No correlation was observed between ΔD and d. For 53 GTVs from five patients with ΔD 1 mm, the difference of GTV DWe found no significant difference in GTV D

The spread through air spaces (STAS) is recognized as a negative prognostic factor in patients with early-stage lung adenocarcinoma. The present study aimed to develop a machine learning model for the prediction of STAS using peritumoral radiomics features extracted from preoperative CT imaging. A total of 339 patients who underwent lobectomy or limited resection for lung adenocarcinoma were included. The patients were randomly divided (3:2) into training and test cohorts. Two prediction models were created using the training cohort: a conventional model based on the tumor consolidation/tumor (C/T) ratio and a machine learning model based on peritumoral radiomics features. The areas under the curve for the two models in the testing cohort were 0.70 and 0.76, respectively (P = 0.045). The cumulative incidence of recurrence (CIR) was significantly higher in the STAS high-risk group when using the radiomics model than that in the low-risk group (44% vs. 4% at 5 years; P = 0.002) in patients who underwent limited resection in the testing cohort. In contrast, the 5-year CIR was not significantly different among patients who underwent lobectomy (17% vs. 11%; P = 0.469). In conclusion, the machine learning model for STAS prediction based on peritumoral radiomics features performed better than the C/T ratio model.

Background The risk for radiation necrosis is lower in fractionated stereotactic radiotherapy (SRT) than in conventional radiotherapy, and 13-fraction SRT is our method of choice for the treatment of brain metastases ≥ around 2 cm or patients who are expected to have a good prognosis. As 13-fraction SRT lasts for at least 17 days, adaptive radiotherapy based on contrast-enhanced mid-treatment magnetic resonance imaging (MRI) is often necessary for patients undergoing 13-fraction SRT. In this study, we retrospectively analyzed interfractional target changes in patients with brain metastases treated with 13-fraction SRT. Methods Our analyses included data from 23 patients and 27 metastatic brain lesions treated with 13-fraction SRT with dynamic conformal arc therapy. The peripheral dose prescribed to the planning target volume (PTV) was 39–44.2 Gy in 13-fractions. The gross tumor volume (GTV) of the initial SRT plan (initial GTV), initial PTV, and modified GTV based on the mid-treatment MRI scan (mid-treatment GTV) were assessed. Results The median initial GTV was 3.8 cm3 and the median time from SRT initiation to the mid-treatment MRI scan was 6 days. Compared to the initial GTV, the mid-treatment GTV increased by more than 20% in five lesions and decreased by more than 20% in five lesions. Interfractional GTV volume changes of more than 20% were not significantly associated with primary disease or the presence of cystic components/necrosis. The mid-treatment GTV did not overlap perfectly with the initial PTV in more than half of the lesions. Conclusions Compared to the initial GTV, the mid-treatment GTV changed by more than 20% in almost one-third of lesions treated with 13-fraction SRT. As SRT usually generates a steep dose gradient as well as increasing the maximum dose of PTV compared to conventional radiotherapy, assessment of the volume and locational target changes and adaptive radiotherapy should be considered as the number of fractions increases.

A new irradiation technique, volumetric-modulated Dynamic WaveArc therapy (VMDWAT), based on sequential non-coplanar trajectories, can be performed using the Vero4DRT. This planning study compared the dose distribution and treatment time between single-isocenter volumetric-modulated arc therapy (VMAT) with multiple straight non-coplanar arcs and single-isocenter VMDWAT in patients with two brain metastases. Twenty patients with two planning target volumes exceeding 2.0 cm3 were included. Both VMAT and VMDWAT plans were created with single isocenter and a prescribed dose of 28 Gy delivered in five fractions. Target conformity was evaluated using indices modified from the RTOG-CI (mRTOG-CI) and IP-CI (mIP-CI). VMDWAT significantly improved both mRTOG-CI and mIP-CI and reduced the volume of normal brain tissue receiving 25 and 28 Gy compared to VMAT. The two modalities did not significantly differ in terms of the volume of normal brain tissue receiving 5, 10, 12, 15, and 20 Gy. The mean treatment time was significantly shorter in the VMDWAT group. VMDWAT significantly improved dose distribution in a shorter treatment time compared to VMAT in patients treated for two brain metastases. Single-isocenter VMDWAT may thus be a promising treatment for two brain metastases.

This study sought to develop and validate a prognostic model for non-lung cancer death (NLCD) in elderly patients with non-small cell lung cancer (NSCLC) treated with stereotactic body radiotherapy (SBRT). Patients aged ≥65 diagnosed with NSCLC (Tis-4N0M0), tumor diameter ≤5 cm and SBRT between 1998 and 2015 were retrospectively registered from two independent institutions. One institution was used for model development (arm D, 353 patients) and the other for validation (arm V, 401 patients). To identify risk factors for NLCD, multiple regression analysis on age, sex, performance status (PS), body mass index (BMI), Charlson comorbidity index (CCI), tumor diameter, histology and T-stage was performed on arm D. A score calculated using the regression coefficient was assigned to each factor and three risk groups were defined based on total score. Scores of 1.0 (BMI ≤18.4), 1.5 (age ≥ 5), 1.5 (PS ≥2), 2.5 (CCI 1 or 2) and 3 (CCI ≥3) were assigned, and risk groups were designated as low (total ≤ 3), intermediate (3.5 or 4) and high (≥4.5). The cumulative incidences of NLCD at 5 years in the low, intermediate and high-risk groups were 6.8, 23 and 40% in arm D, and 23, 19 and 44% in arm V, respectively. The AUC index at 5 years was 0.705 (arm D) and 0.632 (arm V). The proposed scoring system showed usefulness in predicting a high risk of NLCD in elderly patients treated with SBRT for NSCLC.

Objectives The purpose of this study was to assess the radiological change patterns in skull base meningiomas after conventionally fractionated stereotactic radiotherapy (CFSRT) to determine a simple and valid method to assess the tumor response. Materials and methods Forty-one patients with a benign skull base meningioma treated by CFSRT from March 2007 to August 2015 were retrospectively evaluated. We measured tumor volume (TV), long-axis diameter (LD), and short-axis diameter (SD) on both pre-treatment images and follow-up images of 1, 3, and 5 years after CFSRT, respectively. The paired t test was used to detect differences in the LD and SD change rates. Spearman’s correlation coefficients were calculated to evaluate relationships between the TV and the diameters changes. Results The number of available follow-up MRIs that was performed at 1, 3, and 5 years after the CFSRT was 41 (100%), 34 (83%), and 23 (56%), respectively. The change rates of SD were significantly higher than those of LD at every time point and more strongly correlated with the change rates of tumor volume at 3 and 5 years after CFSRT. Conclusions SD may be useful as a simple indicator of the tumor response for skull base meningioma after CFSRT. Key Points • The change rate in short-axis diameter is a useful and simple indicator of the response of skull base meningioma to conventionally fractionated stereotactic radiotherapy. • Conventionally fractionated stereotactic radiotherapy for skull base meningioma achieved excellent 5-year local control.

Mono-isocentric volumetric-modulated arc therapy (VMAT) can be used to treat multiple brain metastases. It remains unknown whether mono-isocentric VMAT can improve the dose distribution compared with dual-isocentric dynamic conformal arc therapy (DCAT), especially for two brain metastases. We compared the dose distribution between dual-isocentric DCAT and mono-isocentric VMAT for two large brain metastases, and analyzed the relationship between the distance between the two targets and the difference in dose distribution. A total of 19 patients, each with two large brain metastases, were enrolled. The dose prescribed for each planning target volume (PTV) was 28 Gy in five fractions (D99.8 = 100%). We created new indices derived from conformity indices suggested by the Radiation Therapy Oncology Group (RTOG; mRTOG-CI) and Paddick et al. (mIP-CI), using the dosimetric parameters of the sum of the two PTVs. The median PTV was 5.05 cm3 (range, 2.10–28.47). VMAT significantly improved mRTOG-CI and mIP-CI compared with DCAT. In all cases, VMAT was able to improve mRTOG-CI and mIP-CI compared with DCAT. Whereas the normal brain volume receiving 5 Gy was similar between the two modalities, the normal brain receiving 10, 12, 15, 20, 25 and 28 Gy (V10–V28) was significantly smaller in VMAT. The mean beam-on times were 213.3 s and 121.9 s in DCAT and VMAT, respectively (P < 0.001). Mono-isocentric VMAT improved the target conformity and reduced the beam-on time and V10–V28 of the normal brain for not only two close metastases but also two distant metastases. Mono-isocentric VMAT seems to be a promising treatment technique for two large brain metastases.

The aim of this study was to assess the clinical outcomes of acoustic neuromas (ANs) treated with hypofractionated stereotactic radiotherapy (hypo-FSRT) prescribed at a uniform dose. Forty-seven patients with a unilateral AN were treated consecutively with hypo-FSRT between February 2007 and March 2012. Nineteen patients maintained a serviceable hearing status at the beginning of hypo-FSRT. The prescribed dose was 25 Gy delivered in five fractions per week to the isocenter, and the planning target volume was covered by the 80% isodose line. The median follow-up and audiometric follow-up periods were 61 and 52 months, respectively. The estimated tumor control rate at 5 years was 90% (95% CI 76–96). The existence of the cystic component before hypo-FSRT had a significantly worse impact on tumor control (p = 0.02). The estimated hearing preservation rates at 1, 3 and 5 years were 68% (95% CI 42–84), 41% (95% CI 20–62) and 36% (95% CI 15–57), respectively. A borderline significant difference was identified in the mean biological effective dose with an α/β value of 3 Gy (BED3) to the ipsilateral cochlea between the preserved hearing and hearing loss groups (19 Gy vs. 28 Gy) (p = 0.08). Hypo-FSRT delivered in five fractions for unilateral ANs may achieve excellent tumor control with no severe facial or trigeminal complications. The mean BED3 in the cochlea may impact the hearing preservation rate. Therefore, the cochlear dose should be as low as possible.

Purpose To validate the clinical applicability of knowledge-based (KB) planning in single-isocenter volumetric-modulated arc therapy (VMAT) for multiple brain metastases using the k-fold cross-validation (CV) method. Methods This study comprised 60 consecutive patients with multiple brain metastases treated with single-isocenter VMAT (28 Gy in five fractions). The patients were divided randomly into five groups (Groups 1-5). The data of Groups 1-4 were used as the training and validation dataset and those of Group 5 were used as the testing dataset. Four KB models were created from three of the training and validation datasets and then applied to the remaining Groups as the fourfold CV phase. As the testing phase, the final KB model was applied to Group 5 and the dose distributions were calculated with a single optimization process. The dose-volume indices (DVIs), modified Ian Paddick Conformity Index (mIPCI), modulation complexity scores for VMAT plans (MCSv), and the total number of monitor units (MUs) of the final KB plan were compared to those of the clinical plan (CL) using a paired Wilcoxon signed-rank test. Results In the fourfold CV phase, no significant differences were observed in the DVIs among the four KB plans (KBPs). In the testing phase, the final KB plan was statistically equivalent to the CL, except for planning target volumes (PTVs) D2% and D50% . The differences between the CL and KBP in terms of the PTV D99.5% , normal brain, and Dmax to all organs at risk (OARs) were not significant. The KBP achieved a lower total number of MUs and higher MCSv than the CL with no significant difference. Conclusions We demonstrated that a KB model in a single-isocenter VMAT for multiple brain metastases was equivalent in dose distribution, MCSv, and total number of MUs to a CL with a single optimization.

Permanent alopecia is a grave late complication of multi-drug chemotherapy (CTx) plus cranial irradiation, reducing both patient self-esteem and quality of life in pediatric patients. We started to use craniospinal irradiation (CSI) using the volumetric-modulated arc whole-brain radiotherapy (VMAT-WBRT) in order to prevent permanent alopecia. We treated 5 pediatric patients with CSI using VMAT-WBRT, and report the initial clinical outcome. Five consecutive patients (4–11 years old) who received CSI using VMAT-WBRT from June 2015 to November 2018 were included into this study. One patient with embryonic carcinoma received radiotherapy (RT) with concurrent CTx; four patients with medulloblastoma (two patients with standard risk, and two patients with high risk) received RT followed by CTx. The prescribed doses of CSI were 23.4–35.2 Gy in 13–22 fractions, respectively. Optimization for VMAT-WBRT was performed to reduce doses to the hair follicles with keeping the dose coverage to the planning target volume. Although all patients experienced temporary alopecia, their hair fully recovered over the whole scalp within 8 months after finishing RT. One patient had disease progression after 6 months after completing CTx; this patient who was diagnosed as Group 3 subtype had diffuse meningeal dissemination confirmed with contrast enhanced spinal MRI before RT. The other four patients had no evidence of recurrence. Although CSI with VMAT-WBRT might be one of considerable options, more cases are needed to verify the efficacy to prevent permanent alopecia for pediatric patients who receive multi-drug CTx and cranial irradiation.

Cystic brain necrosis (CBN) is a rare form of BN. It typically occurs as a very late complication, and no standard treatment has been established. We report a case of a 59-year-old man who developed CBN 10 years after radiation therapy for metastatic brain tumors. The therapy consisted of whole brain radiotherapy followed by linac-based stereotactic radiosurgery as a boost. Initially, the CBN continued to expand despite treatment with corticosteroids and bevacizumab. Therefore, we resected the tumor and implanted an Ommaya reservoir, which successfully stabilized the lesion. Although the prognosis of patients with brain metastases is generally poor, some patients, like the one reported here, achieve long survival. Therefore, we should follow such cases carefully, considering the possibility of developing CBN as a late complication.

The purposes of this study on prostate cancer are to demonstrate the time course of International Prostate Symptom Score (IPSS) after intensity-modulated radiation therapy (IMRT) combined with androgen deprivation therapy (ADT) and to examine the factor associated with the IPSS change. This study included 216 patients treated with IMRT between 2006 and 2010. Patients were evaluated in three groups according to baseline IPSS as defined by the American Urological Association classification, where IPSSs of 0 to 7, 8 to 19, and 20 to 35 represent mild (n = 124), moderate (n = 70), and severe (n = 22) symptom groups, respectively. The average IPSSs ± standard deviation at baseline vs. those at 24 months after IMRT were 3.5 ± 2.1 vs. 5.1 ± 3.6 in the mild group (P < 0.001), 12.6 ± 3.4 vs. 10.0 ± 6.0 in the moderate group (P = 0.0015), and 23.8 ± 2.9 vs. 14.4 ± 9.1 in the severe group (P < 0.001). Among factors of patient and treatment characteristics, age, IPSS classification, pretreatment GU medications, and positive biopsy rates were associated with the IPSS difference between baseline and 24 months (P = 0.023, < 0.001, 0.044, and 0.028, respectively). In conclusion, patients with moderate to severe urinary symptoms can exhibit improvement in urinary function after IMRT, whereas patients with mild symptoms may have slightly worsened functions. Age, baseline IPSS, GU medications, and tumor burden in the prostate can have an effect on the IPSS changes.

Purpose: We assessed the signal of the globus pallidus (GP) in cases of hepatic insufficiency, especially to evaluate the degree of discrepancy in paramagnetic effects on shortening of T1 and T2* using susceptibility-weighted images (SWI). Materials and Methods: Seven patients with hepatic insufficiency underwent magnetic resonance (MR) examinations that included T1-weighted images (T1WI), T2-weighted images (T2WI), and SWI on a 1.5-tesla MR imager, and we compared their results to those of controls. On T1WI and T2WI, we measured signal intensity in the GP and posterior segment of the putamen (Put) to obtain a signal ratio (GP/Put ratio), and on SWI, we classified signal intensity into 4 grades: A, higher than the cortex; B, lower than the cortex and higher than the cerebrospinal fluid (CSF); C, lower than the CSF and higher than the red nucleus; and D, lower than the red nucleus. Results: In the 7 patients with hepatic insufficiency, the mean GP/Put ratio was significantly higher on T1WI and T2WI than those values in controls. On SWI, we classified 2 cases each as Grade A, Grade B, and Grade C, and one as Grade D. Although the signal of the GP was elevated on T1WI, there was no decrease in signal on T2WI. On SWI, we obtained no low signal intensity. Conclusion: In patients with hepatic insufficiency, the globus pallidus did not show low signal intensity on either T2WI or SWI. Hyperintensity of the GP on T1WI without hypointensity on T2WI, or even SWI, suggests a discrepancy between paramagnetic effect on T1 and T2 shortening that reflects the accumulation of manganese and the presence of hepatic insufficiency.