title: [Application of amorphous silicon electronic portal imaging device (a-Si EPID) to dosimetry quality assurance of radiation therapy].
abstract: OBJECTIVE
  Due to its good dosimetric properties, amorphous silicon electronic portal imaging device (a-Si EPID), as a rapid two-dimensional dosimetric measurement device, presents an attractive prospect in routine quality assurance (QA) test, dosimetric verification of intensity-modulated radiotherapy treatment (IMRT) and in vivo dose monitoring. This study was to explore the application of a-Si EPID as a detector for dosimetric QA of linear accelerator radiotherapy, and setup the calibration module.
  
  
  METHODS
  The imaging calibration procedure of conventional a-Si EPID was modified for dosimetric measurement by acquiring the traditional "flush field" from integrated subfields to correct the dosimetric responding difference in pixel sensitivity. The energy dependence of the a-Si EPID detectors was analyzed through off-axis dose response curves. Calibrated dose profile obtained with a-Si EPID was compared with the measuring results of ion chamber in a 3-D water phantom.
  
  
  RESULTS
  The calibrated dose profiles measured with a-Si EPID showed a deviation within 2% in high dose regions, but dropped much steeply in the penumbra region, as compared with that scanned using ion chamber in water.
  
  
  CONCLUSIONS
  With the modeling management set up in this research, a-Si EPID can be applied for dosimetric QA of linear accelerator in radiotherapy.
authors.affiliation: State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, PR China.
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Chen
authors.forename: Xiao-Wu
authors.initials: XW
authors.lastname: Deng
authors.forename: Shao-Min
authors.initials: SM
authors.lastname: Huang
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: De-Hua
authors.initials: DH
authors.lastname: Kang
mesh_terms: D004307:Dose-Response Relationship, Radiation; D010315:Particle Accelerators; D011786:Quality Control; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D012825:Silicon
chemical_list: D012825:Silicon