An Application of Trajectory Log for Volumetric Intensity Modulated Arc Therapy (VIMAT) Plan Quality Assurance in a Digitally Integrated and Controlled Linear Accelerator

Chan, Shannon M.; Lau, Steven; Lee, K.; Kam, Kai‐Man; Yu, Kin Wah; Chan, Anthony T.C.

doi:10.1016/j.ijrobp.2013.06.1884

Cited by 1 publication

(6 citation statements)

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“…Magnitude of MLC errors (RMS <0.3 mm) and maximum gantry angle deviation (<0.2 degree) in this study for VMAT SBRT were similar to that reported for VMAT deliveries by Mcgarry, et al (RMS <0.16 mm) and Chan, et al (<0.1 degree) respectively 13,14 . Minor differences between studies might be due to the differences in the mechanical accuracy between machines such as the extent of degradation of MLC motors and wearing of gantry chain.…”

Section: Discussionsupporting

confidence: 85%

“…Magnitude of MLC errors (RMS <0.3 mm) and maximum gantry angle deviation (<0.2 degree) in this study for VMAT SBRT were 13,14 Minor differences between studies might be due to the differences of MLC positions, gantry angles, and differential dose indices with magnitudes of 1 mm, 1 degree, and 5 % respectively, while the passing rate of gamma analysis from ArcCheck TM measurement was still higher than 95 % tolerance that would be recognized as a pass…”

Section: Discussionmentioning

confidence: 52%

“…13,14 Chan et al conducted a preliminary study on quantifying the deviations of monitor unit (MU) and gantry angles during delivery against the plan through log analysis for three head and neck and three prostate VMAT cases. 14 Mcgarry et al quantified the plan delivery accuracy in terms of log file-derived MLC positioning error with single center-specific plan and single standard plan for each participating center in VMAT audits. 13 However, no comprehensive study with a large number of clinical cases has been conducted to evaluate simultaneously the deviations of MU, gantry angles, and MLC positions against the planned values using machine log files.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Several studies have been performed to evaluate the efficiency and effectiveness of machine log file analysis for volumetric‐modulated arc therapy (VMAT) 13,14 . Chan et al conducted a preliminary study on quantifying the deviations of monitor unit (MU) and gantry angles during delivery against the plan through log analysis for three head and neck and three prostate VMAT cases 14 . Mcgarry et al quantified the plan delivery accuracy in terms of log file‐derived MLC positioning error with single center‐specific plan and single standard plan for each participating center in VMAT audits 13 .…”

Section: Introductionmentioning

confidence: 99%

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Patient‐specific quality assurance using machine log files analysis for stereotactic body radiation therapy (SBRT)

Chow

Kan

Chan

2020

J Applied Clin Med Phys

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An in-house trajectory log analysis program (LOGQA) was developed to evaluate the delivery accuracy of volumetric-modulated arc therapy (VMAT) for stereotactic body radiation therapy (SBRT). Methods have been established in LOGQA to provide analysis on dose indices, gantry angles, and multi-leaf collimator (MLC) positions. Between March 2019 and May 2020, 120 VMAT SBRT plans of various treatment sites using flattening filter-free (FFF) mode were evaluated using both LOGQA and phantom measurements. Gantry angles, dose indices, and MLC positions were extracted from log and compared with each plan. Integrated transient fluence map (ITFM) was reconstructed from log to examine the deviation of delivered fluence against the planned one. Average correlation coefficient of dose index versus gantry angle and ITFM for all patients were 1.0000, indicating that the delivered beam parameters were in good agreement with planned values. Maximum deviation of gantry angles and monitor units (MU) of all patients were less than 0.2 degree and 0.03 % respectively. Regarding MLC positions, maximum and rootmean-square (RMS) deviations from planned values were less than 0.6 mm and 0.3 mm respectively, indicating that MLC positions during delivery followed planned values in precise manner. Results of LOGQA were consistent with measurement, where all gamma-index passing rates were larger than 95 %, with 2 %/2 mm criteria. Three types of intentional errors were introduced to patient plan for software validation. LOGQA was found to recognize the introduced errors of MLC positions, gantry angles, and dose indices with magnitudes of 1 mm, 1 degree, and 5 %, respectively, which were masked in phantom measurement. LOGQA was demonstrated to have the potential to reduce or even replace patient-specific QA measurements for SBRT plan delivery provided that the frequency and amount of measurement-based machine-specific QA can be increased to ensure the log files record real values of machine parameters.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 52%