Analisis Pengaruh Variasi Sudut Penyinaran terhadap Kontras dan Ketajaman Kualitas Citra pada Pemeriksaan Radiografi Digital di Instalasi Radiologi Rumah Sakit Bhayangkara Bondowoso

Abstract

Digital radiography using a Computed Radiography (CR) system requires good image quality to provide optimal diagnostic information. One factor that can affect image quality is variation in the angle of irradiation. This study aims to analyze the effect of variations in the angle of irradiation on the contrast and sharpness of digital radiographic images from a CR system using a flask phantom. The study was conducted with irradiation angles of 0°, 10°, 15°, 20°, and 25° at a tube voltage of 60 kVp and a current of 25 mAs. Each angle was tested three times, resulting in 27 radiographic images in DICOM format. Image quality analysis was performed by calculating contrast, Contrast-to-Noise Ratio (CNR), sharpness, and Modulation Transfer Function (MTF). . The data were analyzed using the Kruskal Wallis test with a significance level of 5%, as well as Dunn’s post-hoc test for parameters showing significant differences. The results of the study indicate that variations in the illumination angle do not have a significant effect on image contrast (p > 0.05). The relatively stable CNR values across all angle variations support these results. Conversely, variations in the illumination angle had a significant effect on image sharpness (p < 0.05). The results of the Dunn post-hoc test showed a significant difference between the 0° and 20° angle pairs. MTF analysis revealed a curve pattern consistent with the theoretical characteristics of digital imaging systems and supported the image sharpness measurement results. It can be concluded that variations in the illumination angle within the 0°–25° range do notsignificantly affect image contrast but do affect the sharpness of digital radiographic images in CR systems.