Optimization of Imaging Parameters in Micro-CT Scanner Based On Signal-To-Noise Ratio for the Analysis of Urinary Stone Composition

Abstract

Introduction: Micro-CT scanner with a resolution of about 5 micrometers is one of the modalities used to create three-dimensional/two-dimensional images of urinary stones. This study aimed to optimize imaging parameters in micro-computed tomography (CT) scanner based on the signal-to-noise ratio (SNR) of urinary stones for the analysis of stone composition. Material and Methods: In this study,eight micro-CT scanning protocols were applied to five urinary stones taken from different patients. Each scanning protocol had different voltage, current, and exposure parameters. The reconstructed images were then analyzed based on image brightness and SNR. The optimized imaging parameters which were chosen were that having high SNR because the high-quality image has high SNR. Results: The results showed that two groups of urinary stones had the same mean Hounsfield Units (HU) value in the third scanning protocols (i.e., 65 kV, 123 µA, and 850 ms). Mean HU values in group one (i.e., stones numbered 1, 3, and 4) were reported as 790, 760, and 720, respectively. The second group (i.e., stones numbered 2 and 5) had mean HU values of -514 and -343, respectively. The imaging parameters (i.e., 75 kV, 106 µA, and 600 ms) had high SNR (25-34) for the first group. The SNR (12.8-13.25) was for the second group at imaging parameters (i.e., 85 kV, 94 µA, and 500 ms). Conclusion: Based on the SNR, the two optimal imaging parameters for the first and second groups were reported as 75 kV, 106 µA, and 600 ms, as well as 85 kV, 94 µA, and 500 ms, respectively.