Optimizing radiation exposure in screening of body packing: image quality and diagnostic acceptability of an 80 kVp protocol with automated tube current modulation.

Abstract

The aim of this study was to evaluate the objective and subjective image quality of a novel computed tomography (CT) protocol with reduced radiation dose for body packing with 80 kVp and automated tube current modulation (ATCM) compared to a standard body packing CT protocol. 80 individuals who were examined between March 2012 and July 2015 in suspicion of ingested drug packets were retrospectively included in this study. Thirty-one CT examinations were performed using ATCM and a fixed tube voltage of 80 kVp (group A). Forty-nine CT examinations were performed using a standard protocol with a tube voltage of 120 kVp and a fixed tube current time product of 40 mAs (group B). Subjective and objective image quality and visibility of drug packets were assessed. Radiation exposure of both protocols was compared. Contrast-to-noise ratio (group A: 0.56±0.36; group B: 1.13±0.91) and Signal-to-noise ratio (group A: 3.69±0.98; group B: 7.08±2.67) were significantly lower for group A compared to group B (p<0.001). Subjectively, image quality was decreased for group A compared to group B (2.5±0.8 vs. 1.2±0.4; p<0.001). Attenuation of body packets was higher with the new protocol (group A: 362.2±70.3 Hounsfield Units (HU); group B: 210.6±60.2 HU; p=0.005). Volumetric Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) were significantly lower in group A (CTDIvol 2.2±0.9mGy, DLP 105.7±52.3 mGycm) as compared to group B (CTDIvol 2.7±0.1mGy, DLP 126.0±9.7 mGycm, p=0.002 and p=0.01). The novel 80 kVp CT protocol with ATCM leads to a significant dose reduction compared to a standard CT body packing protocol. The novel protocol led to a diagnostic image quality and cocaine body packets were reliably detected due to the high attenuation.