Dosimetric verification of IMRT and 3D conformal treatment delivery using EPID.

Purpose: Electronic portal imaging devices (EPIDs) could potentially be useful for either in-vivo or pre-treatment dosimetric verification of external beam radiation therapy. The accuracy of EPID for dosimetric purposes is highly dependent on the specific method used for the determination of dose-response characteristics. The aim of this study was to develop a simple and time-saving EPID back-projection dosimetry algorithm for 2D dose verification in 3D conformal and intensity-modulated beams.

An Empirical Transmitted EPID Dosimetry Method using a Back-Projection Algorithm.

Background: The present study aimed to introduce a rapid transmission dosimetry through an electronic portal-imaging device (EPID) to achieve two-dimensional (2D) dose distribution for homogenous environments.

Material And Methods: In this Phantom study, first, the EPID calibration curve and correction coefficients for field size were obtained from EPID and ionization chamber. Second, the EPID off-axis pixel response was measured, and the grey-scale image of the EPID was converted into portal dose image using the calibration curve.