Current status of 3D EPID-based in vivo dosimetry in The Netherlands Cancer Institute

8th International Conference on 3D Radiation Dosimetry

Mijnheer, B.^1 ; Olaciregui-Ruiz, I.^1 ; Rozendaal, R.^1 ; Spreeuw, H.^1 ; Van Herk, M.^1 ; Mans, A.^1

Department of Radiation Oncology, Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam

1066 CX, Netherlands^1

关键词: Anatomical changes;    Backprojection algorithms;    Clinical procedure;    Dose distributions;    Dose reconstruction;    Dose verification;    Evaluation software;    Patient specific;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/573/1/012014/pdf
DOI  :  10.1088/1742-6596/573/1/012014

来源: IOP

【 摘 要 】

3D in vivo dose verification using a-Si EPIDs is performed routinely in our institution for almost all RT treatments. The EPID-based 3D dose distribution is reconstructed using a back-projection algorithm and compared with the planned dose distribution using 3D gamma evaluation. Dose-reconstruction and gamma-evaluation software runs automatically, and deviations outside the alert criteria are immediately available and investigated, in combination with inspection of cone-beam CT scans. The implementation of our 3D EPID- based in vivo dosimetry approach was able to replace pre-treatment verification for more than 90% of the patient treatments. Clinically relevant deviations could be detected for approximately 1 out of 300 patient treatments (IMRT and VMAT). Most of these errors were patient related anatomical changes or deviations from the routine clinical procedure, and would not have been detected by pre-treatment verification. Moreover, 3D EPID-based in vivo dose verification is a fast and accurate tool to assure the safe delivery of RT treatments. It provides clinically more useful information and is less time consuming than pre-treatment verification measurements. Automated 3D in vivo dosimetry is therefore a prerequisite for large-scale implementation of patient-specific quality assurance of RT treatments.