Evaluation and comparison of image quality for indirect flat panel systems with CsI and GOS scintillators

Abstract

Aim: The objective of this study is to compare the image quality of flat panel systems that have cesium iodide (CsI) and gadolinium oxysulfate (GOS) scintillators in their detectors. Method: CDRAD 2.0 phantom and CDRAD analyzer software is used for objective evaluation and comparison of image quality of flat panel systems with CsI and GOS scintillators. The image quality is investigated in terms of contrast and detail. Nine different flat panel systems from 6 different manufacturers are evaluated in this study. Four of these flat panels have CsI scintillators and the remaining 5 have GoS scintillators. For evaluations, 20 layers of plexiglass were placed on the top (10 layers) and bottom (10 layers) of the CDRAD 2.0 phantom to simulate a patient. 3 images were taken from each system at each dose level, which were analyzed by the CDRAD 2.0 analyzer software. Image qualities were investigated at four different dose levels (50, 100, 150, and 200 μGys). IQFinv is used as the quality metric. Results: IQFinv values of GOS systems have little variance both within the same system and between all systems. On the other hand, CsI systems have higher variance in IQFinv values within the same system and between the systems. In addition, same CsI detectors (same model from the same manufacturer) used in different systems resulted in considerably different IQFinv values. CsI systems demonstrate 4–5 times more improvement in IQFinv value with increasing dose levels compared to GOS systems. Finally, IQFinv values of CsI systems are higher than GOS systems with statistically significance (p<0.029).