Program Information
MLCs Performance and Patient-Specific IMRT QA Using Log File Analysis
A Osman1,3*, N Maalej1 , K Jayesh2 , W Abdel-Rahman2 , (1) King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia, (2) King Fahad Specialist Hospital-Dammam, Eastern Province, Saudi Arabia (3) American University of Beirut Medical Center, Beirut, Lebanon
Presentations
SU-F-T-295 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To analyze the performance of the multi-leaf collimators (MLCs) from the log files recorded during the intensity modulated radiotherapy (IMRT) treatment and to construct the relative fluence maps and do the gamma analysis to compare the planned and executed MLCs movement.
Methods: We developed a program to extract and analyze the data from dynamic log files (dynalog files) generated from sliding window IMRT treatment delivery. The program extracts the planned and executed (actual or delivered) MLCs movement and dose rate fractions data, calculates and compares the relative planned and executed fluences. The fluence maps were used to perform the gamma analysis (with 3% dose difference and 3 mm distance to agreement) for 3 IMRT patients. We compared our gamma analysis results with those obtained from dose evaluation algorithm in the portal dosimetry task performed using the EPID.
Results: For 3 different IMRT patient treatments, the maximum difference between the planned and the executed MLCs positions was 1.2 mm. The gamma analysis results of the planned and delivered fluences were in good agreement with the gamma analysis from portal dosimetry. The maximum difference in the number of pixels passing the gamma criteria (3%/3mm) was 0.19% with respect to portal dosimetry results.
Conclusion: MLCs log files can be used to verify the performance of the MLCs. Patient-specific IMRT QA based on MLCs log files gives similar results to EPID dosimetry results. This promising method for patient-specific IMRT QA is fast, does not require dose measurements in a phantom, can be done before the treatment and for every fraction, and significantly reduces the IMRT plan QA workload.
Funding Support, Disclosures, and Conflict of Interest: The author would like to thank King Fahd University of petroleum and Minerals for the support.
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