title: Clinical practice and evaluation of electronic portal imaging device for VMAT quality assurance.
abstract: Volumetric-modulated arc therapy (VMAT) is a novel extension of the intensity-modulated radiation therapy (IMRT) technique, which has brought challenges to dose verification. To perform VMAT pretreatment quality assurance, an electronic portal imaging device (EPID) can be applied. This study's aim was to evaluate EPID performance for VMAT dose verification. First, dosimetric characteristics of EPID were investigated. Then 10 selected VMAT dose plans were measured by EPID with the rotational method. The overall variation of EPID dosimetric characteristics was within 1.4% for VMAT. The film system serving as a conventional tool for verification showed good agreement both with EPID measurements ([94.1 ± 1.5]% with 3 mm/3% criteria) and treatment planning system (TPS) calculations ([97.4 ± 2.8]% with 3 mm/3% criteria). In addition, EPID measurements for VMAT presented good agreement with TPS calculations ([99.1 ± 0.6]% with 3 mm/3% criteria). The EPID system performed the robustness of potential error findings in TPS calculations and the delivery system. This study demonstrated that an EPID system can be used as a reliable and efficient quality assurance tool for VMAT dose verification.
authors.affiliation: Department of Radiation Oncology, Chang Gung Memorial Hospital, Keelung Branch, Keelung City, Taiwan. yenchohuang@hotmail.com
authors.forename: Yen-Cho
authors.initials: YC
authors.lastname: Huang
authors.forename: Chien-Yi
authors.initials: CY
authors.lastname: Yeh
authors.forename: Jih-Hsiang
authors.initials: JH
authors.lastname: Yeh
authors.forename: Ching-Jung
authors.initials: CJ
authors.lastname: Lo
authors.forename: Ping-Fang
authors.initials: PF
authors.lastname: Tsai
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Hung
authors.forename: Chieh-Sheng
authors.initials: CS
authors.lastname: Tsai
authors.forename: Chen-Yuan
authors.initials: CY
authors.lastname: Chen
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D011785:Quality Assurance, Health Care / Q000379:methods* / Q000592:standards; D011874:Radiometry / Q000295:instrumentation* / Q000592:standards*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation* / Q000592:standards*; D013624:Taiwan; D014963:X-Ray Intensifying Screens / Q000592:standards*