TITLE:
Predicting Delivery Error Using a DICOM-RT Plan for Volumetric Modulated Arc Therapy
AUTHORS:
Hideharu Miura, Masao Tanooka, Masayuki Fujiwara, Yasuhiro Takada, Hiroshi Doi, Soichi Odawara, Kengo Kosaka, Norihiko Kamikonya, Shozo Hirota
KEYWORDS:
Volumetric-Modulated Arc Therapy, DICOM-RT Plan, Patient-Specific QA, Radiotherapy Planning, Computer-Assisted
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.3 No.2,
May
8,
2014
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.