title: Effect of beam profile measurement on arc therapy plan quality assurance: a case study.
abstract: 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.
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center at Cooper, 2 Cooper Plaza, Camden, NJ, 08103, USA.
authors.forename: Leonard H
authors.initials: LH
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center at Cooper, 2 Cooper Plaza, Camden, NJ, 08103, USA.
authors.forename: Irina
authors.initials: I
authors.lastname: Malajovich
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center at Cooper, 2 Cooper Plaza, Camden, NJ, 08103, USA.
authors.forename: Meral L
authors.initials: ML
authors.lastname: Reyhan
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center at Cooper, 2 Cooper Plaza, Camden, NJ, 08103, USA.
authors.forename: Jinyu
authors.initials: J
authors.lastname: Xue
authors.affiliation: Department of Radiation Oncology, MD Anderson Cancer Center at Cooper, 2 Cooper Plaza, Camden, NJ, 08103, USA.
authors.forename: Joo Han
authors.initials: JH
authors.lastname: Park
mesh_terms: D010315:Particle Accelerators; D011785:Quality Assurance, Health Care; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation* / Q000379:methods*
keywords: arc therapy; beam modeling; quality assurance