Tracy Anne Jaffe MD, Presenter: Nothing to Disclose

Susan Marie Delaney, Abstract Co-Author: Nothing to Disclose

Ana Maria Gaca MD, Abstract Co-Author: Nothing to Disclose

Lynne Hurwitz MD, Abstract Co-Author: Nothing to Disclose

Terry T. Yoshizumi PhD, Abstract Co-Author: Research support, General Electric Company

Greta Toncheva BS, Abstract Co-Author: Nothing to Disclose

Giao Nguyen, Abstract Co-Author: Nothing to Disclose

Donald Paul Frush MD, Abstract Co-Author: Research funded, General Electric Company

et al, Abstract Co-Author: Nothing to Disclose

To compare organ and effective doses for small bowel follow through (SBFT) and abdominal pelvic MDCT scans in imaging adults with Crohn’s disease (CD).

Average fluoroscopic time for SBFT was determined by reviewing records in 30 CD patients. Using an adult female anthropomorphic phantom (CIRS, Norfolk, VA) and MOSFET detectors (Thomson-Nielson, Ottawa, Canada), specific organ doses were measured for 5 minutes of continuous fluoroscopy (kVp=120, mA 0.6) of each of the following: right lower quadrant (RLQ), central abdomen (CA), and pelvis (P). Effective doses were determined for these fluoroscopic regions based on IRCP 60 weighting factors. Organ and effective doses were determined for 16-slice MDCT (GE Healthcare, Milwaukee, WI) using the following protocol: 16x0.625mm, pitch 1.75, 17.5mm/rotation, 0.5 seconds, 140 kVp, 340 mA. Review of records was performed to determine number of patients imaged for CD indications. Number of SBFTs and CTs were recorded.

Average fluoroscopic time for clinical SBFT was 4.9 minutes. Highest organ doses in RLQ were right kidney (0.78 cGy) and bone marrow (0.66 cGy). Highest organ doses in CA were bilateral kidneys and bone marrow (1.5 and 1.6 cGy, 0.76 cGy, respectively), and highest doses in P were found in bone marrow (0.67-0.95 cGy). Effective doses for RLQ, CA, and P were 1.37, 2.02 and 3.83 mSv, respectively. For MDCT, highest organ doses were bladder (5.71 cGy), uterus (5.19 cGy), and ovaries (4.10 cGy). Effective dose for abdominal pelvic MDCT was 13.3 mSv. 397 patients underwent imaging for CD from 1990-2005. Average number of SBFT was 1.7 (range 0-15) and average number of CT exams was 2.1 (range 0-50). 31/397 (8%) patients underwent >5 CTs and 11/397 (3%) had >10 CTs.

Specific organ and effective doses are up to five times higher with abdominal pelvic MDCT than SBFT. CD is more frequently imaged with CT, and a subset of patients has numerous CT exams. In this population, concerted effort should be made to minimize number of CTs, decrease CT dose or consider MR enterography.

A subset of patients with Crohn's disease undergo frequent imaging and are at risk for sizable radiation doses to radiosensitive organs.

Jaffe, T, Delaney, S, Gaca, A, Hurwitz, L, Yoshizumi, T, Toncheva, G, Nguyen, G, Frush, D, et al, , Radiation Doses from Small Bowel Follow through and Abdominal Pelvic MDCT in Crohn’s Disease.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4427787.html