Inter-unit variability of multi-leaf collimator parameters for IMRT and VMAT treatment planning: a multi-institutional survey
| Autor: | Hirokazu Mizuno, Toshijiro Yamamoto, Yuichi Akino, Masaru Isono, Norihisa Masai, Yoshihiro Tanaka |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Computer science
Health Toxicology and Mutagenesis Linear particle accelerator 030218 nuclear medicine & medical imaging law.invention 03 medical and health sciences 0302 clinical medicine law Surveys and Questionnaires Regular Paper Confidence Intervals Humans Radiology Nuclear Medicine and imaging dosimetric leaf gap Radiation treatment planning Simulation Medical systems Radiation Radiotherapy Planning Computer-Assisted Truebeam Collimator Source surface Radiotherapy Dosage Multi leaf collimator 030220 oncology & carcinogenesis MLC leaf transmission IMRT/VMAT commissioning Radiotherapy Intensity-Modulated |
| Zdroj: | Journal of Radiation Research |
| ISSN: | 1349-9157 0449-3060 |
| Popis: | Modern treatment machines have shown small inter-unit variability regarding beam data. Recently, vendor-provided average beam data, such as the Representative Beam Data (RBD) of the TrueBeam (Varian Medical Systems, Palo Alto, CA, USA), has been used for modeling of the Eclipse (Varian Medical Systems) treatment planning system. However, RBD does not provide multi-leaf collimator (MLC) parameters, such as MLC leaf transmission factor (LTF) and dosimetric leaf gap (DLG). We performed a web-based multi-institutional survey to investigate these parameters as well as the measurement protocols and customization of the parameters for intensity-modulated radiotherapy (IMRT) and/or volumetric modulated radiotherapy (VMAT) commissioning. We collected 69 sets of linear accelerator (linac) data from 58 institutions. In order to measure MLC parameters, most institutions used farmer-type ionization chambers with a sensitive volume of 0.6 cm3, water phantoms, source surface distance of 90 cm with 10 cm depth, and a vendor-provided plan. The LTF showed small inter-unit variabilities, although the DLG showed large variations. For optimization of the parameters for IMRT/VMAT calculations, DLG values were upwardly adjusted at many institutions, whereas the LTF values were modestly changed. We clarified that MLC parameters were measured under the same conditions at more than half of the facilities. Most institutions customized parameters in a similar manner for IMRT/VMAT. The median measured and customized values obtained in our study will be valuable to verify MLC installation accuracy and to shorten the iterative processes of finding the optimal values. |
| Databáze: | OpenAIRE |
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