Purpose: The target delineation of whole ventricle radiotherapy (WVRT) in germinoma varies among radiation oncologists, especially regarding the inclusion of the prepontine cistern (PC). We evaluated the outcome of PC-sparing WVRT in localized germinoma. Materials and Methods: We identified 87 localized intracranial germinoma patients who received radiotherapy (RT) following chemotherapy between 1999 and 2020. By institutional policy, RT for localized germinoma excluded PC from the target volume. WVRT was delivered to 65 patients (74.7%) and involved field radiotherapy (IFRT) to 22 patients (25.3%). The median dose was 45.0 Gy (range, 23.4 to 55.8 Gy) for the primary tumor and 19.8 Gy (rangem 14.4 to 36.0 Gy) for the whole ventricle. We analyzed the dosimetric differences of the organs at risk between the PC-excluding plans and the PC-including ones. Results: The median follow-up duration was 7.8 years (range, 1.0 to 22.5 years). The 10-year recurrence-free survival and overall survival rates were 86.3% and 90.9%, respectively. The recurrences occurred in eight patients (8.7%), including five patients after IFRT and three after WVRT. Five of them showed recurrences at lateral ventricles and only one patient experienced spinal cord relapse. However, no relapse in the PC occurred. Endoscopic third ventriculostomy was not a significant prognostic factor. The dosimetric comparisons showed significantly lower mean doses to the brainstem and the cochleae when the PC was excluded. Conclusion WVRT for localized germinoma can safely exclude the PC in the target volume, reducing radiation dose to the brain stem. The target protocol needs to reach a consensus regarding the PC in prospective trials.

Purpose: This study aims to evaluate the impact of smaller gantry arc increment (GAI) values on the plan quality and deliverability of volumetric modulated arc therapy (VMAT) for head and neck (HN) and prostate cancer cases using the Monaco treatment planning system. The study investigates whether a smaller GAI can enhance organ at risk (OAR) sparing without compromising target coverage or significantly increasing plan complexity. Methods: VMAT plans were created for 20 patients (10 HN and 10 prostate cancer) using GAI values of 15° and 30°. Dose-volumetric parameters, such as conformity number, homogeneity and gradient indices, were assessed alongside plan complexity metrics like the modulation complexityscore for VMAT (MCS v ) and monitor unit (MU). Statistical significance was determined using the Wilcoxon signed-rank test. Results: For HN cases, a 15° increment significantly reduced the D0.03cc for the spinal cord and the Dmean for both parotid glands compared to a 30° increment, improving OAR sparing. However, no significant differences were observed in the OAR doses for prostate cases. The 15° increment resulted in higher plan complexity, reflected by a lower MCS v , but the MU difference was not significant. Conclusions Smaller GAI values, such as 15°, can significantly reduce OAR doses in HN VMAT plans, offering potential clinical benefits despite increased plan complexity. However, no substantial advantages were observed in prostate cases. These findings suggest that smaller GAI values may be particularly beneficial for cases requiring high modulation.

Purpose: This study aims to evaluate the impact of smaller gantry arc increment (GAI) values on the plan quality and deliverability of volumetric modulated arc therapy (VMAT) for head and neck (HN) and prostate cancer cases using the Monaco treatment planning system. The study investigates whether a smaller GAI can enhance organ at risk (OAR) sparing without compromising target coverage or significantly increasing plan complexity. Methods: VMAT plans were created for 20 patients (10 HN and 10 prostate cancer) using GAI values of 15° and 30°. Dose-volumetric parameters, such as conformity number, homogeneity and gradient indices, were assessed alongside plan complexity metrics like the modulation complexityscore for VMAT (MCS v ) and monitor unit (MU). Statistical significance was determined using the Wilcoxon signed-rank test. Results: For HN cases, a 15° increment significantly reduced the D0.03cc for the spinal cord and the Dmean for both parotid glands compared to a 30° increment, improving OAR sparing. However, no significant differences were observed in the OAR doses for prostate cases. The 15° increment resulted in higher plan complexity, reflected by a lower MCS v , but the MU difference was not significant. Conclusions Smaller GAI values, such as 15°, can significantly reduce OAR doses in HN VMAT plans, offering potential clinical benefits despite increased plan complexity. However, no substantial advantages were observed in prostate cases. These findings suggest that smaller GAI values may be particularly beneficial for cases requiring high modulation.

Purpose: This study aims to evaluate the impact of smaller gantry arc increment (GAI) values on the plan quality and deliverability of volumetric modulated arc therapy (VMAT) for head and neck (HN) and prostate cancer cases using the Monaco treatment planning system. The study investigates whether a smaller GAI can enhance organ at risk (OAR) sparing without compromising target coverage or significantly increasing plan complexity. Methods: VMAT plans were created for 20 patients (10 HN and 10 prostate cancer) using GAI values of 15° and 30°. Dose-volumetric parameters, such as conformity number, homogeneity and gradient indices, were assessed alongside plan complexity metrics like the modulation complexityscore for VMAT (MCS v ) and monitor unit (MU). Statistical significance was determined using the Wilcoxon signed-rank test. Results: For HN cases, a 15° increment significantly reduced the D0.03cc for the spinal cord and the Dmean for both parotid glands compared to a 30° increment, improving OAR sparing. However, no significant differences were observed in the OAR doses for prostate cases. The 15° increment resulted in higher plan complexity, reflected by a lower MCS v , but the MU difference was not significant. Conclusions Smaller GAI values, such as 15°, can significantly reduce OAR doses in HN VMAT plans, offering potential clinical benefits despite increased plan complexity. However, no substantial advantages were observed in prostate cases. These findings suggest that smaller GAI values may be particularly beneficial for cases requiring high modulation.

Purpose: This study aims to evaluate the impact of smaller gantry arc increment (GAI) values on the plan quality and deliverability of volumetric modulated arc therapy (VMAT) for head and neck (HN) and prostate cancer cases using the Monaco treatment planning system. The study investigates whether a smaller GAI can enhance organ at risk (OAR) sparing without compromising target coverage or significantly increasing plan complexity. Methods: VMAT plans were created for 20 patients (10 HN and 10 prostate cancer) using GAI values of 15° and 30°. Dose-volumetric parameters, such as conformity number, homogeneity and gradient indices, were assessed alongside plan complexity metrics like the modulation complexityscore for VMAT (MCS v ) and monitor unit (MU). Statistical significance was determined using the Wilcoxon signed-rank test. Results: For HN cases, a 15° increment significantly reduced the D0.03cc for the spinal cord and the Dmean for both parotid glands compared to a 30° increment, improving OAR sparing. However, no significant differences were observed in the OAR doses for prostate cases. The 15° increment resulted in higher plan complexity, reflected by a lower MCS v , but the MU difference was not significant. Conclusions Smaller GAI values, such as 15°, can significantly reduce OAR doses in HN VMAT plans, offering potential clinical benefits despite increased plan complexity. However, no substantial advantages were observed in prostate cases. These findings suggest that smaller GAI values may be particularly beneficial for cases requiring high modulation.

Purpose: This study aims to evaluate the impact of smaller gantry arc increment (GAI) values on the plan quality and deliverability of volumetric modulated arc therapy (VMAT) for head and neck (HN) and prostate cancer cases using the Monaco treatment planning system. The study investigates whether a smaller GAI can enhance organ at risk (OAR) sparing without compromising target coverage or significantly increasing plan complexity. Methods: VMAT plans were created for 20 patients (10 HN and 10 prostate cancer) using GAI values of 15° and 30°. Dose-volumetric parameters, such as conformity number, homogeneity and gradient indices, were assessed alongside plan complexity metrics like the modulation complexityscore for VMAT (MCS v ) and monitor unit (MU). Statistical significance was determined using the Wilcoxon signed-rank test. Results: For HN cases, a 15° increment significantly reduced the D0.03cc for the spinal cord and the Dmean for both parotid glands compared to a 30° increment, improving OAR sparing. However, no significant differences were observed in the OAR doses for prostate cases. The 15° increment resulted in higher plan complexity, reflected by a lower MCS v , but the MU difference was not significant. Conclusions Smaller GAI values, such as 15°, can significantly reduce OAR doses in HN VMAT plans, offering potential clinical benefits despite increased plan complexity. However, no substantial advantages were observed in prostate cases. These findings suggest that smaller GAI values may be particularly beneficial for cases requiring high modulation.