Optimization of Radiation Dose and Image Quality in Computed Tomography Imaging

Abstract

Improvements in the benefit of CT have been so dramatic that a tendency exists to the overuse. CT is a diagnostic imaging modality giving higher patient dose in comparison with other radiological procedures. While the benefits of CT exceed the harmful effects of radiation exposure in patients, increasing radiation doses to the population have raised. The main objective of this work was to find an optimization approach to minimize the radiation dose to adult patients undergoing CT examinations, while maintaining the diagnostic image quality. This study was done on four different CT scanners (2, 4, 16 and 64), in Khartoum state, during the period 2013-2016. One way to achieve optimization is to reduce tube rotation time, which has been shown to be effective in reducing absorbed dose to patients undergoing CT examinations. A total of 404 CT patients’ examinations 240 before and164 after optimization were included in the study. The results from this study indicate that radiation dose DLP was reduced significantly by (14.3%-59.7%) mGy.cm in Brain Protocol and by (1.1%-28.2%) mGy.cm in Chest Protocol and by (16.2%-55.4%) mGy.cm in Abdomen protocol for the four scanners. Image noise generally increases, subjective image quality was affected by an increased noise level in the images but was judged to be acceptable in all groups.Using this protocol, effective dose was reduced by (22.9%-47.0%) mSv in Brain and (2.6%- 25.3%) mSv in Chest and (15.6%-49.2%) mSv in Abdomen which in turns reduced the cancer probability. This study showed that optimizing the dose and image quality for the four CT scanners is dependent on choosing the appropriate parameter for the exam protocol. Finally, concerted efforts and research should be directed to define IV diagnostic image quality, and research efforts must focus on patient- and technology- based methods to achieve a diagnostic- quality CT image at an optimum radiation dose. A team approach is essential in CT protocol review. And there is still considerable room for optimization and continuous developments of new technologies aim to optimize image quality and radiation absorbed dose to the patient.