Ji-Won Kang MD, Presenter: Nothing to Disclose

Kyung-Hyun Do MD, Abstract Co-Author: Nothing to Disclose

Kichang Han MD, Abstract Co-Author: Nothing to Disclose

Eun Jin Chae MD, PhD, Abstract Co-Author: Nothing to Disclose

Dong Hyun Yang MD, Abstract Co-Author: Nothing to Disclose

Choong Wook Lee MD, Abstract Co-Author: Nothing to Disclose

To analyze tendency of CT protocol changes and dose reduction from 2007 to 2012, after establishment of thoracic CT guidelines on 2008.

We retrospectively reviewed CT scans from nationwide hospitals; one group from 2007-05-01 to 2007-05-31 and the other group from 2012-01-01 to 2012-01-31. A total of 100 CT scans from 2007 and 173 CT scans from 2012 were included by selecting only one CT scan from each hospital. In addition, each group was divided into two subgroups (A and B) by the level of hospitals; “A” subgroup from primary care hospitals and “B” subgroup from secondary and tertiary care hospitals. We obtained patient information, CT scan protocols, and CT dose parameters. Two radiologists analyzed the image quality and scan range according to thoracic CT guidelines.  

When comparing the data from 2007 and 2012, tube current significantly decreased from 179.1 mean mAs to 137.2 mean mAs. Tube voltage decreased from 121.8 kVp to 120.5 kVp, which was not statistically significant.  There were no significant changes in thickness and phase, either. Scan interval decreased from 6.4 mm to 4.8 mm. Insufficient scan range decreased from 19.0 % to 8.7 %.  Suboptimal quality scans decreased from 33.0 % to 5.2 %. No significant change in excessive scan range was seen.  Between group A and B, group B has lower tube voltage, smaller scan thickness and smaller scan interval both in 2007 and 2012. Group B has more phases in 2012, when compared to group A.  In group A, insufficient scan range, which was prevlent in 2007, was statistically reduced in 2012.  In group B, excessive scan range, which was 57.8% in 2007, remains to be as high as 46.4% in 2012. In terms of suboptimal quality scan, a signicant decrease was seen in both groups.   

 During 5-year period from 2007 to 2012, a reduction in mAs can be interpreted as a decrease in radiation doses. Despite a lower radiation dose, the overall image quality was improved. We assume that these changes are attributed to the introduction of thoracic CT guidelines in 2008. However, excessive scan range and suboptimal quality scan still exist as CT protocols vary from hospital to hosiptal. In that sense, continuous education and dissemination of the guidlines are critical. 

 Based on this study, the introduction of guidelines served as a platform to bring about those changes. Furthermore, the result of this study may be utilitzed for future revisions of the guidelines.

Kang, J, Do, K, Han, K, Chae, E, Yang, D, Lee, C, Survey of Thoracic CT Protocols and Technical Parameters in Korean Hospitals: Tendency of CT Protocol Change before and after Establishment of Thoracic CT Guidelines by Korean Society of Thoracic Radiology (KSTR).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045733.html