Detection of bodypacks: Accuracy of abdominal radiography versus very low dose CT

Purpose The aim of this study was to investigate the detectability of bodypacks in low dose computed tomography (CT) in comparison to abdominal radiography (AR). Materials and method Bodypacks ( n =13 to n =20 per body) were placed into the small intestines of 9 human corpses. In each case AR and CT at different dose levels were performed: standard dose for abdominal CT scans (CTDI=8.5 mGy/cm), 1/2 dose (CTDI=4.3 mGy/cm), 1/4 dose (CTDI=2.1 mGy/cm), 1/8 dose (CTDI=1.1 mGy/cm), 1/16 dose (CTDI=0.6 mGy/cm), and technical minimal dose of 1/60 (CTDI=0.14 mGy/cm). Two independent observers counted the number of bodypacks in each CT dataset and in the AR. Radiation exposure was estimated for CT using the dose-length-product and for AR using the area-dose-product. Results Intra- and interobserver agreement was good. Image noise at CT ranged between 17 HU (at standard dose) and 300 HU (at technical minimal dose). At AR, the accuracy for the detection of bodypacks had a sensitivity of 59% and a specificity of 97% at an average radiation exposure of 1.0 mSv. In CT, all bodypacks were detected at every dose level (sensitivity and specificity: 100%). The calculated radiation exposure ranged from 10.9 mSv (at standard dose) to 0.2 mSv (at technical minimal dose). Discussion CT permits detection of all bodypacks even at minimal dose levels of 0.2 mSv. Therefore, the use of very low-dose CT is recommendable for the detection of bodypacks in suspected traffickers as low-dose CT provides a superior accuracy and a lower radiation exposure than AR.