Determination of Patient Dose from Exposure Index (EI) in Digital Imaging

The Exposure Index (EI) is an accepted metric in modern radiography practice that indicates digital detector response to incident radiation. The EI provides feedback to the radiographer on the exposure techniques applied. For example, an overexposed image will display an incorrect EI. In the spirit of ALARA dose management, it is of interest in our experimental study to determine the level of agreement between phantom doses acquired by applying both direct dose measurement methods and indirect dose measurement methods. Our direct dose measurement methods included the use of self-developing radiochromic film (RCF) XR-RV3 which was calibrated against a gold-standard reference dosimeter, the Unfors solid state detector. Indirect dose measurement involved recording the equipment dose-area-product (DAP) meter readout as well as using third party virtual radiography simulation software, TechnicVR v2.0 (Shaderware Ltd, UK).