Open AccessEffect of beam profile measurement on arc therapy plan quality assurance: a case study
Author(s) -
Kim Leonard H.,
Malajovich Irina,
Reyhan Meral L.,
Xue Jinyu,
Park Joo Han
Publication year - 2017
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.12071
Subject(s) - multileaf collimator , quality assurance , collimator , arc (geometry) , beam (structure) , linear particle accelerator , optics , medical physics , computer science , mathematics , physics , engineering , geometry , operations management , external quality assessment
We present an example when profile measurement and modeling of an Elekta Agility multileaf collimator (MLC) had a large effect specifically on arc therapy plan quality assurance (QA) results using ArcCheck. ArcCheck absolute dose measurements of these plans were systematically lower than planned by 3–10%. Failing QA results were seen even with unmodulated static and conformal arcs. Furthermore, the effect was found to be dependent on collimator angle, with worse results associated with near‐zero collimator angles. In contrast, step‐and‐shoot QA results were not affected. Changing the beam model to match steeper profile measurements obtained using a different measurement device resolved the problem. This case study demonstrates that conventional gamma index analysis can be sensitive to small profile modeling changes.