Assessment of Radiation Dose and Image Quality of Multidetector Computed Tomography

Abstract

Background: CT techniques and procedures have been expanded in the past decades, leading to an increase in the use of CT. At the same time, the radiation dose to the patient and the concern surrounding this issue has also increased. Objectives: The goal of this study was to assess clinical image quality and x-ray dose from various computed tomography (CT) scanners in order to identify the CT scanners that produce the least radiation dose to patients with exact acceptable image quality for diagnosis. Patients and Methods: Non-randomized clinical image data were collected from six hospitals on 16, 32 and 64 slice CT scanners. A total of 900 patients who underwent chest, abdomen, and brain scans were used for image quality evaluation and dose assessment. The image qualities were evaluated by five observers on 1 - 5 visual grading scale. The CT dose volume index (CTDIv) and dose length product (DLP) was documented from the image display. Results: The averaged CTDIv was 64.96, 70.2, and 75 mGy for the brain, 11.65, 15.53 and 17.11 mGy for the chest, and 13.41, 18.44, and 19.42 mGy for the abdomen from 16, 32 and 64 slice scanners respectively. The averaged image quality scores were 3.68, 3.82, and 4.81 for the abdomen, 3.01, 4.27, and 4.42 for the chest, and 4.92, 4.94, and 4.99 for the brain from 16, 32 and 64 slice scanners respectively. Conclusion: Sixteen slice CT scanner delivered the minimum radiation dose to patients in contrast with the 32 and 64 slice CT scanners, and the image quality was adequate for diagnosis. Both 32 and 64 slice CT scanners produced more than acceptable image quality as well as more than needed dose to patients. The patient dose from the 32 and 64 slice scanners may be reduced by dropping their image quality to close to the 16 slice CT scanner.