TITLE:
Feasibility of Estimating Patient-Specific Dose Verification Results Directly from Linear Accelerator Log Files in Volumetric Modulated Arc Therapy
AUTHORS:
Kengo Kosaka, Masao Tanooka, Hiroshi Doi, Hiroyuki Inoue, Kazuo Tarutani, Hitomi Suzuki, Yasuhiro Takada, Masayuki Fujiwara, Norihiko Kamikonya, Shozo Hirota
KEYWORDS:
Radiotherapy, VMAT, Log File, Patient Specific QA, Correlation, Gamma Index
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.5 No.4,
November
21,
2016
ABSTRACT: The feasibility
of estimating patient-specific dose verification results directly from linear
accelerator (linac) log files has been investigated for prostate cancer
patients who undergo volumetric modulated arc therapy (VMAT). Twenty-six
patients who underwent VMAT in our facility were consecutively selected. VMAT
plans were created using Monaco treatment planning system and were transferred
to an Elekta linac. During the beam delivery, dynamic machine parameters such
as positions of the multi-leaf collimator and the gantry were recorded in the
log files; subsequently, root mean square (rms) values of control errors,
speeds and accelerations of the above machine parameters were calculated for
each delivery. Dose verification was performed for all the plans using a
cylindrical phantom with diodes placed in a spiral array. The gamma index pass
rates were evaluated under 3%/3 mm and 2%/2 mm criteria with a dose threshold
of 10%. Subsequently, the correlation coefficients between the gamma index pass
rates and each of the above rms values were calculated. Under the 2%/2 mm
criteria, significant negative correlations were found between the gamma index
pass rates and the rms gantry angle errors (r = 0.64, p r
= 0.68, p