Woo Kyoung Jeong MD, Presenter: Nothing to Disclose

Ah Young Kim MD, Abstract Co-Author: Nothing to Disclose

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

To investigate radiation doses for abdominal computed tomography (CT) and their differences among multi-detector row CT (MDCT) using various protocols and to evaluate their allowance with the diagnostic reference levels

A total of 464 consecutive CT scans taken on the abdomen and pelvis using 16-channel MDCT were enrolled. These scans were divided into 1) general abdomen (including pre and/or post-enhanced CT); 2) dynamic abdomen with thick (including most of dynamic liver CT; collimation, 1.5 mm) and thin collimation (including some of dynamic liver, pancreas, biliary CT and specific study for liver transplantation; collimation, 0.75 mm); and 3) other specific CT protocols such as CT colonography, CT gastrography, and CT enterography. We compared protocols as follows; number of scanning per study, mean volumetric CT dose index (CTDIv) and dose length product (DLP). Then, we also compared radiation dose at our institution with reference levels of European guidelines on quality criteria for CT (EUR 16262). Statistical analysis for comparison between each protocol was ANOVA test with a p-value < 0.05 for significance.

The mean numbers of scanning in dynamic and other specific CT protocols were 3.53 and 2.91, respectively, and larger than general protocol (mean, 1.23) significantly. Mean CTDIv of general CT protocol (9.99 ± 1.82 mGy) was larger than other CT protocols (9.35 ± 1.98 mGy; 7.91 ± 3.29 mGy), but mean DLP (610 ± 209 mGy•cm) was smaller than others (1052 ± 339 mGy•cm; 932 ± 293 mGy•cm). Of the dynamic CT protocol, mean CTDIv of the groups with thin collimation (9.71 ± 1.92 mGy) was larger than those with thick collimation (9.05 ± 1.98 mGy), but mean DLP (966 ± 246 mGy•cm) was smaller than the thick (1124 ± 386 mGy•cm). According to EUR 16262, the DLPs of dynamic and some specific CT protocols were larger than the reference levels (780-900 mGy•cm), but those of general CT and CT colonography were permissible (610 ± 363 mGy•cm and 730 ± 364 mGy•cm, respectively).

Except CT colonography, effective dose of MDCT in abdominal imaging was significantly increased with dynamic and some specific CT protocols as compared with general CT protocol.

It is necessary to adjust the radiation dose down because effective dose was increased after using MDCT, except CT colonography.

Jeong, W, Kim, A, Do, K, Survey of CT Radiation Dose in Abdominal Imaging: Focusing on Dose Differences according to Various CT Protocols of Multidetector Row CT.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6019558.html