Assessing the influence of X-ray spectrum on image quality in abdominal computed tomography scans

Abstract

This work aims to evaluate the effect of acquisition parameters of the abdominal computed tomography protocol on image quality and dose, including the contrast-to-noise ratio (CNR), noise, spatial resolution (SR) as well as volumetric computed tomography dose index (CTDIvol). The measurements have been performed on a 16-slice HITACHI scanner using the polymethylmethacrylate phantom for CTDIvol and Catphan 500 for image quality. Two tube voltages of 120 kVp and 100 kVp have been analyzed while varying the tube current settings from 100 to 300 (mA) to measure image quality quantities and dose (CTDIvol). The scanning with 100 kVp compared to 120 kVp has led to a dose reduction up to 38% at mAs ranging from 100 to 300, a decrease in CNR by 28%, with a slight decrease in spatial resolution accompanied by an increase in noise. This work has shown that despite the increase in noise at 100 kVp, it is possible to reduce the dose without affecting the quantities of spatial resolution and the contrast/noise ratio by lowering the tube voltage from 120 kVp to 100 kVp.