Clinical implementation of 3D in vivo dosimetry for abdominal and pelvic stereotactic treatments
Autor: | Marco Esposito, L. Paoletti, S. Fondelli, P. Alpi, Serenella Russo, Paolo Bastiani, A. Ghirelli, S. Pini, Barbara Grilli Leonulli, Francesca Rossi, R. Barca |
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Rok vydání: | 2019 |
Předmět: |
business.industry
Radiotherapy Planning Computer-Assisted Epid dosimetry Planning target volume Radiotherapy Dosage Hematology SABR volatility model In Vivo Dosimetry 030218 nuclear medicine & medical imaging Pelvis Stereotactic radiotherapy 03 medical and health sciences 0302 clinical medicine Oncology 030220 oncology & carcinogenesis LOCAL TOLERANCE Abdomen Medicine Humans Radiology Nuclear Medicine and imaging Radiotherapy Intensity-Modulated In vivo dosimetry Nuclear medicine business Radiometry |
Zdroj: | Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 154 |
ISSN: | 1879-0887 |
Popis: | Purpose To analyze results from three years of in vivo transit EPID dosimetry of abdominal and pelvic stereotactic radiotherapy and to establish tolerance levels for routine clinical use. Material 80 stereotactic VMAT treatments (152 fractions) targeting the abdomen or pelvis were analyzed. In vivo 3D doses were reconstructed with an EPID commercial algorithm. Gamma Agreement Index (GAI) and DVH differences in Planning Target Volume (PTV) and Clinical Target Volume (CTV) were evaluated. Initial tolerance level was set to GAI > 85% in PTV. Fractions Over Tolerance Level (OTL) were deemed to be due to set-up errors, incorrect use of immobilization devices, 4D errors, transit EPID algorithm errors and unknown/unidentified errors. Statistical Process Control (SPC) was applied to determine local tolerance levels. Results Average GAI were (82.7 ± 20.9) % in PTV and (72.9 ± 29.7) % in CTV. 37.8% of fractions resulted OTL and were classified as: set-up errors (3.3%), incorrect use of immobilization devices (2.1%), 4D errors (2.1%), EPID transit algorithm errors (17.1%). OTL causes for the remaining 13.2% of fractions were not identified. The differences between PTV and CTV measured in vivo and calculated mean dose (average difference ± standard deviation) were (−3.3% ± 3.2%) and (−2.3% ± 3.0%). When tolerance levels based on SPC to PTV mean dose differences were applied, the percentage of OTL decreased to 7% and no EPID algorithm error occurred. One error was not identified. Conclusions The application of local tolerance levels to EPID in vivo dosimetry proved to be useful for detecting extra-lung SBRT treatment errors. |
Databáze: | OpenAIRE |
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