ANALYSIS OF EXPOSURE INDEX AND DEVIATION INDEX IN AEC MODE FOR RADIOGRAPHIC IMAGE QUALITY IMPROVEMENT AT THUNG SONG HOSPITAL

Abstract

This study aimed to 1) Analyze and compare the Exposure Index (EI) and Deviation Index (DI) values obtained from two digital radiography machines using the Automatic Exposure Control (AEC) mode. 2) Investigate the relationship between EI and DI with imaging parameters (kVp and mAs), and 3) Establish optimal parameter settings for the AEC system to ensure consistent image quality and patient safety. This experimental research utilized a total of 62 chest posteroanterior (PA) radiographs acquired in AEC mode, retrieved from the hospital’s PACS. The dataset included 31 images from each of the two machines and additional measurements from a Phantom chest model. EI and DI values were extracted from PACS, and image quality was assessed by three radiologists using a 5-point Likert scale. Data were analyzed using independent t-tests and regression analysis. The results revealed that 1) There was no statistically significant difference in EI values between the two machines (p = 0.109), while DI values showed a significant difference (p < 0.00001), with Machine B producing DI values closest to zero. 2) A low correlation was observed between EI and kVp (r = 0.227), and a very weak negative correlation between DI and mAs (r = -0.114). 3) Machine B, operating at 110 kVp and 3.56 mAs, yielded DI values nearest to zero and the highest image quality scores, indicating a more stable AEC performance. These findings highlight the necessity of establishing machine-specific standard values for EI and DI to ensure consistent image quality, reduce unnecessary radiation exposure, and enhance diagnostic accuracy.