| Abstrakt: |
Purpose: To compare radiation dose and image quality of abdominal CT for patients who underwent repeated CT examinations before and after adjustment of scan protocol. Materials and Methods:We compared radiation dose and image quality of repeated abdominal CT scans (at three-year-interval) of 50 patients with chronic liver disease, 50 patients with early gastric cancer, and 50 patients with uterine cancer. To reduce radiation dose, we optimzed CT protocols by omitting unnecessary pre-contrast phase, reducing kVp, and setting higher noise index. Data o f dose reports were collected. Objective image quality was evaluated for noise level, signal to noise ratio (SNR), and con tra st noise ratio (CNR). For subjective image quality, we evaluated image noise, contrast, and overall diagnostic acceptability. Results: The mean values of dose length product of 2011 CT scans compared to those of 2008 CT scans were 27.6% to 45.7%. The image noise level, SNR, and CNR were significantly (p< 0.05) worse in 2011 CT scans compared to 2008 CT scans. For subjective image quality, image noise was also significantly (p <0.05) worse in 2011. However, CNR and diagnostic acceptability showed variable results. No CT scans were considered as unacceptable image. Conclusion: We modified abdominal CT protocols to reduce radiation exposure. [ABSTRACT FROM AUTHOR] |
