%0 Journal Article
%T Dosimetric Comparison of Amorphous Silicon EPID and 2D Array Detector for Pre-Treatment Verification of Intensity Modulated Radiation Therapy
%A Ayman G. Ibrahim
%A Ismail E. Mohamed
%A Hamdy M. Zidan
%J International Journal of Medical Physics,Clinical Engineering and Radiation Oncology
%P 438-452
%@ 2168-5444
%D 2018
%I Scientific Research Publishing
%R 10.4236/ijmpcero.2018.74037
%X Purpose: To
study the dosimetric characteristics of amorphous silicon Electronic Portal
Imaging Device EPID and 2D array detector for dose verification of
radiotherapy treatment plans, and the quality assurance QA testing of IMRT was investigated. Materials and methods: All measurements were done with Varian IX linear
accelerator, aSi-1000 EPID and 2D array detector. The dose linearity, reproducibility,
output factors, dose rate, SDD and response with slap phantom thickness have
been measured and compared against those measured by ion chamber. Results: The characteristics of EPID
and 2D array: the response of EPID agreed with 2D array and ion chamber 0.6cc.
EPID and 2D array showed short-term output reproducibility with SD = 0.1%. The
dose rates of 2D array SD = ¡À0.7%, EPID = ¡À0.4% compared with a 0.6 cc SD = ¡À0.5%. Output factor measurements for the central
chamber of the EPID and 2D array showed no considerable deviation from ion
chamber measurements. Measurement of beam profiles with the EPID and 2D array
matched very well with the ion chamber measurements in the water phantom. The
EPID is more sensitive to lower energy photons by increasing solid water
phantom thickness. The mean and standard deviation passing rates (<i>¦Ã</i>%<sub>¡Ü1</sub>) for film, 2D array and EPID for 30 IMRT fields of
five patients were 95.93 ¡À