Premium
Dosimetric verification of IMAT delivery with a conventional EPID system and a commercial portal dose image prediction tool
Author(s) -
Iori Mauro,
Cagni Elisabetta,
Paiusco Marta,
Munro Peter,
Nahum Alan E.
Publication year - 2010
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3271107
Subject(s) - dosimetry , image guided radiation therapy , linear particle accelerator , medical imaging , computer science , radiation treatment planning , medical physics , nuclear medicine , radiation therapy , medicine , radiology , physics , artificial intelligence , beam (structure) , optics
Purpose The electronic portal imaging device (EPID) is a system for checking the patient setup; as a result of its integration with the linear accelerator and software customized for dosimetry, it is increasingly used for verification of the delivery of fixed‐field intensity‐modulated radiation therapy (IMRT). In order to extend such an approach to intensity‐modulated arc therapy (IMAT), the combined use of an EPID system and a portal dose image prediction (PDIP) tool has been investigated. Methods The dosimetric behavior of an EPID system, mechanically reinforced to maintain its positional stability during the accelerator gantry rotation, has been studied to assess its ability to measure portal dose distributions for IMAT treatment beams. In addition, the PDIP tool of a commercial treatment planning system, commonly used for static IMRT dosimetry, has been validated for simulating the PDIs of IMAT treatment fields. The method has been applied to the delivery verification of 23 treatment fields that were measured in their dual mode of IMRT and IMAT modalities. Results The EPID system has proved to be appropriate for measuring the PDIs of IMAT fields; additionally the PDIP tool was able to simulate these accurately. The results are quite similar to those obtained for static IMRT treatment verification, although it was necessary to investigate the dependence of the EPID signal and of the accelerator monitor chamber response on variable dose rate. Conclusions Our initial tests indicate that the EPID system, together with the PDIP tool, is a suitable device for the verification of IMAT plan delivery; however, additional tests are necessary to confirm these results.