[Application of amorphous silicon electronic portal imaging device (a-Si EPID) to dosimetry quality assurance of radiation therapy].
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.
Chen
Ming-Wei
MW
State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, 510060, PR China.
Deng
Xiao-Wu
XW
Huang
Shao-Min
SM
Chen
Li
L
Kang
De-Hua
DH
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
D012825:Silicon