The Influence of Alteration of kVp and mAs towards the Image Quality of Acrylic Using CBCT

Abstract

CBCT is a modernized technology in producing radiograph image on dentistry. The image quality excellence is very important for clinicians to interpret the image, so the result of diagnosis produced becoming more accurate, appropriate, thus minimizing the working time. This research was aimed to assess the image quality using the blank acrylic phantom polymethylmethacrylate (PMMA) (C­5H8O2)n in the density of 1.185 g/cm3 for evaluating the homogeneity and uniformity of the image produced. Acrylic phantom was supported with a tripod and laid down on the chin rest of the CBCT device, then the phantom was fixed, and the edge of the phantom was touched by the bite block. Furthermore, the exposure of the X-ray was executed toward the acrylic phantom with various kVp and mAs, from 80 until 90, with the range of 5 kV and the variation of mA was 3, 5, and 7 mA respectively. The time exposure was kept constant for 25 seconds. The samples were taken from CBCT acrylic images, then as much as 5 ROIs (Region of Interest) was chosen to be analyzed. The ROIs determination was analyzed by using the ImageJ® software for recognizing the influence of kVp and mAs towards the image uniformity, noise and SNR. The lowest kVp and mAs had the result of uniformity value, homogeneity and signal to noise ratio of 11.22; 40.35; and 5.96 respectively. Meanwhile, the highest kVp and mAs had uniformity value, homogeneity and signal to noise ratio of 16.96; 26.20; and 5.95 respectively. There were significant differences between the image uniformity and homogeneity on the lowest kVp and mAs compared to the highest kVp and mAs, as analyzed with the ANOVA statistics analysis continued with the t-student post-hoc test with α = 0.05. However, there was no significant difference in SNR as analyzed with the ANOVA statistic analysis. The usage of the higher kVp and mAs caused the improvement of the image homogeneity and uniformity compared to the lower kVp and mAs.

Comparative Evaluation of Artifacts Originated by Four Different Post Materials Using Different CBCT Settings

“…The presence of posts within the root canal generates artifacts, which may hinder the examination of diagnosis of several endodontic conditions. Therefore, when CBCT is required in areas containing post materials, the clinician must be aware that these artifacts may alter the true diagnosis [8,19].…”

“…The usage of a higher kVp and mAs improves image homogeneity and uniformity compared to the lower kVp and mAs [8]. Voxel size is directly related to the spatial resolution of an image; as voxel size decreases, resolution and detail increase.…”

The Influence of X-Ray Tube Current-Time Variations Toward Signal to Noise Ratio (SNR) in Digital Radiography: A Phantom Study

“…The amount of radiation utilized to diagnose and sculpt image quality is the most crucial aspect of radiation exposure optimization [5]- [7]. The manufacturer, the government, and/or the user's experience are typically the sources of information used to regulate radiation levels or other criteria.…”

“…It is inappropriate to set the exposure parameter too high, but it is also unacceptable to set the exposure parameter too low [6]. Tube voltage (kVp), tube current (mA), and exposure time (s) are variables that might affect the quality of the image [7].…”