Benchmarking intermediate dose spillage in single target stereotactic radiosurgery for brain metastases.
5 affiliations
- 1Department of Radiation Oncology, University Hospital Bonn, Venusberg-Campus 1, Bonn, Germany.
- 2University Clinic for Medical Radiation Physics, Medical Campus Pius Hospital, Carl von Ossietzky University, Oldenburg, Germany.
- 3Institute of Experimental Oncology, University Hospital Bonn, Bonn, Germany.
- 4Department of Radiation Physics, University Hospital Leipzig, Stephanstrasse 9a, Leipzig, Germany.
- 5Department of Radiation Oncology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Abstract
Background and purpose
Intermediate-dose spillage is central to normal-brain sparing in stereotactic radiosurgery, yet fixed adverse-event and relative indices do not define achievable plan quality for single-target linear accelerator treatments. The aim was to derive a volume-dependent absolute benchmark for the 50% prescription isodose volume (V50%; equivalent to V10 Gy for 20 Gy plans) for brain metastases.Materials and methods
In total, 276 single-isocenter single-target plans were analyzed: 178 idealized model plans and 98 clinical plans. Power-law regression in log-log space modeled spillage against planning target volume (PTV, cm³). The volume-scaling exponents were 0.83 for the ideal references and 0.75 for the simplified clinical threshold. The clinical upper threshold was derived using q = 0.90 quantile regression. Threshold-exceeding plans were reviewed for anatomical or technical justification.Results
In the model cohort V50% value correlated strongly with PTV (r = 0.994, p < 0.001). The ideal mean model was V50% = 3.71 × PTV0.83, the conservative ideal-planning reference was V50% = 4.10 × PTV0.83, and the clinical upper threshold was V50% = 5.00 × PTV0.75. Ten of 98 clinical plans (10%) exceeded the threshold. Seven lacked anatomical justification and were replanned, reducing V50% by a median of 14% (range 7-29%) without compromising target coverage.Conclusions
A volume-based V50% benchmark provided a complementary quality-assurance reference for single-target linear accelerator radiosurgery for brain metastases. It flagged plans that warranted structured review alongside target coverage, organs of interest, conformity, and gradient metrics.
Related
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- Dosimetric Comparison of Contemporary Stereotactic Radiotherapy Platforms for Brain Metastases: Towards Personalized Technology Selection
- Clinical application of MR-Only in cyberknife stereotactic radiotherapy for brain metastases: a feasibility study
BibTeX
@article{nour2026benchmarking,
title = {{Benchmarking intermediate dose spillage in single target stereotactic radiosurgery for brain metastases.}},
author = {Youness Nour and Shari Wiegreffe and Tuba Tekin and Lara Caglayan and Christina Leitzen and Cas S Dejonckheere and Davide Scafa and Julian P Layer and Victoria Volkenborn and Fabian Kugel and Stephan Garbe and Christos Moustakis and Dimos Baltas and Gustavo R Sarria and Anca-L Grosu and Eleni Gkika},
journal = {Physics and imaging in radiation oncology},
year = {2026},
month = sep,
doi = {10.1016/j.phro.2026.101105},
url = {https://europepmc.org/article/MED/42904134},
note = {CC BY},
}
RIS
TY - JOUR
TI - Benchmarking intermediate dose spillage in single target stereotactic radiosurgery for brain metastases.
AU - Youness Nour
AU - Shari Wiegreffe
AU - Tuba Tekin
AU - Lara Caglayan
AU - Christina Leitzen
AU - Cas S Dejonckheere
AU - Davide Scafa
AU - Julian P Layer
AU - Victoria Volkenborn
AU - Fabian Kugel
AU - Stephan Garbe
AU - Christos Moustakis
AU - Dimos Baltas
AU - Gustavo R Sarria
AU - Anca-L Grosu
AU - Eleni Gkika
PY - 2026
DA - 2026/09/01
JO - Physics and imaging in radiation oncology
DO - 10.1016/j.phro.2026.101105
UR - https://europepmc.org/article/MED/42904134
AB - Background and purpose Intermediate-dose spillage is central to normal-brain sparing in stereotactic radiosurgery, yet fixed adverse-event and relative indices do not define achievable plan quality for single-target linear accelerator treatments. The aim was to derive a volume-dependent absolute benchmark for the 50% prescription isodose volume (V50%; equivalent to V10 Gy for 20 Gy plans) for brain metastases.Materials and methods In total, 276 single-isocenter single-target plans were analyzed: 178 idealized model plans and 98 clinical plans. Power-law regression in log-log space modeled spillage against planning target volume (PTV, cm³). The volume-scaling exponents were 0.83 for the ideal references and 0.75 for the simplified clinical threshold. The clinical upper threshold was derived using q = 0.90 quantile regression. Threshold-exceeding plans were reviewed for anatomical or technical justification.Results In the model cohort V50% value correlated strongly with PTV (r = 0.994, p < 0.001). The ideal mean model was V50% = 3.71 × PTV0.83, the conservative ideal-planning reference was V50% = 4.10 × PTV0.83, and the clinical upper threshold was V50% = 5.00 × PTV0.75. Ten of 98 clinical plans (10%) exceeded the threshold. Seven lacked anatomical justification and were replanned, reducing V50% by a median of 14% (range 7-29%) without compromising target coverage.Conclusions A volume-based V50% benchmark provided a complementary quality-assurance reference for single-target linear accelerator radiosurgery for brain metastases. It flagged plans that warranted structured review alongside target coverage, organs of interest, conformity, and gradient metrics.
SN - 2405-6316
ER -