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SU‐E‐T‐62: A Quality Control Computer Program for MLC Leafs Position Verification in IMRT
Author(s) -
Lazos D,
Sillanpaa J,
Furhang E,
Harrison L
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612013
Subject(s) - truebeam , computer science , radiation treatment planning , quality assurance , eclipse , nuclear medicine , fiducial marker , position (finance) , proton therapy , linear particle accelerator , beam (structure) , physics , radiation therapy , medicine , optics , surgery , artificial intelligence , external quality assessment , finance , pathology , astronomy , economics
Purpose: We developed a computer program for independent review of the treatment delivery process, with focus on the verification of the MLC leaf positions during treatment. The program compares the treatment delivery files that the Linac creates after each treatment with the file that contains the parameters of the plan. Methods: During each dynamic treatment, the MLC controller records information related to MLC motion—dose fraction, tolerance, gantry angle, beam‐hold flag, gantry position, and the positions of each leaf, sampled at a rate of 100 times per second. Recording continues until the dynamic treatment is completed or terminated. These binary and text log‐files of treatment machine (TrueBeam, Varian, Palo Alto, CA) are compared against the plan file as it is exported by our treatment planning system EclipseTM TPS (Varian, Palo Alto, CA). The program finds the control points of the Eclipse file that any of the treatment parameter was off by a difference above predefined tolerance values. The tolerance values are user selectable: in our implementation they were 1 deg for gantry and colim. angle, 1 mm for jaws and 0.2 mm for leafs. A verification report for each patient is created including the parameters that exceeded tolerance. Verification reports are created either for all daily treatments, or for all completed treatments of the same patient, thus checking the constancy of treatment parameters over time. The program is developed using the FreeMat computation tool. Results: The program was applied on 40 IMRT plans (300 beams in total). The computation time is about 30 sec per plan (9 beams per plan assumed), mostly spent on searching in Eclipse‐exported files and parameters. Conclusions: This program is a step towards the automation in paperless radiation therapy quality management. Study partially supported by Varian.