Abstract
The purpose of this study was to investigate the prediction of mechanical error using DICOM-RT plan parameters for volumetric modulated arc therapy (VMAT). We created plans for gantry rotation arcs of 360° and 180° (full-arc and half-arc VMAT) for six maxillary sinus cancer cases using a Monaco treatment planning system, and delivered the doses with a linear accelerator. We calculated DICOM-RT plan parameters, including gantry, multileaf collimator (MLC) positions and Monitor Units (MU). We compared plans with regard to gantry angle per MU (degrees/MU) and MLC travel per MU (mm/MU) for each segment. Calculated gantry angle/MLC position speeds and errors were evaluated by comparison with the log file. On average, the half-arc VMAT plan resulted in 47% and 35% fewer degrees/MU and mm/MU than the full-arc VMAT plan, respectively. The root mean square (r.m.s.) gantry and MLC speeds showed a linear relationship with calculated degrees/MU and mm/MU, with coefficients of determination (R2) of 0.86 and 0.72, respectively. The r.m.s. gantry angle and MLC position errors showed a linear relationship with calculated degrees/MU and mm/MU with R2 of 0.63 and 0.76, respectively. Deviations from plan parameters were related to mechanical error for VMAT, and provided quantitative information without the need for VMAT delivery. These parameters can be used in the selection of treatment planning.
Highlights
Volumetric-modulated arc therapy (VMAT) is the administration of intensity-modulated radiotherapy (IMRT) in a single gantry arc, in which gantry speed, dose rate, and multileaf collimator (MLC) leaf speed are varied during gantry rotation [1]
We investigated the prediction of mechanical error when using DICOM-RT VMAT plan parameters, assessing delivery by recording gantry angle and MLC position errors during VMAT delivery in a log file
The half-arc VMAT plan resulted in 47% and 35% fewer degrees/monitor units (MU) and mm/MU than the full-arc VMAT plan
Summary
Volumetric-modulated arc therapy (VMAT) is the administration of intensity-modulated radiotherapy (IMRT) in a single gantry arc, in which gantry speed, dose rate, and multileaf collimator (MLC) leaf speed are varied during gantry rotation [1]. VMAT is comparable to IMRT, but features decreased delivery time and lower monitor units (MU) [2]. Newer phantoms have been developed for VMAT include the Delta (Scandidos, Uppsala, Sweden) [5] and ArcCHECK (Sun Nuclear Corp., Melbourne FL, USA) [6], as well as electronic portal imaging devices (EPID) [7] that can replace film measurement. These devices cannot evaluate plan parameters such as gantry or MLC position
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: International Journal of Medical Physics, Clinical Engineering and Radiation Oncology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.