Dose monitoring using the DICOM structured report: assessment of the relationship between cumulative radiation exposure and BMI in abdominal CT

Abstract

Aim: To perform a systematic, large-scale analysis using the Digital Imaging and Communication in Medicine structured report (DICOM-SR) to assess the relationship between body mass index (BMI) and radiation exposure in abdominal CT.

Materials and methods: A retrospective analysis of DICOM-SR of 3121 abdominal CT examinations between April 2013 and March 2014 was performed. All examinations were conducted using a 128 row CT system. Patients (mean age 61 ± 15 years) were divided into five groups according to their BMI: group A <20 kg/m(2) (underweight), group B 20-25 kg/m(2) (normal weight), group C 25-30 kg/m(2) (overweight), group D 30-35 kg/m(2) (obese), and group E > 35 kg/m(2) (extremely obese). CT dose index (CTDIvol) and dose-length product (DLP) were compared between all groups and matched to national diagnostic reference values.

Results: The mean CTDIvol and DLP were 5.4 ± 2.9 mGy and 243 ± 153 mGy.cm in group A, 6 ± 3.6 mGy and 264 ± 179 mGy.cm in group B, 7 ± 3.6 mGy and 320 ± 180 mGy.cm in group C, 8.1 ± 5.2 mGy and 375 ± 306 mGy.cm in group D, and 10 ± 8 mGy and 476 ± 403 mGy.cm in group E, respectively. Except for group A versus group B, CTDIvol and DLP differed significantly between all groups (p<0.05). Significantly more CTDIvol values exceeded national diagnostic reference values in groups D and E (2.1% and 6.3%) compared to group B (0.5%, p<0.05).

Conclusion: DICOM-SR is a comprehensive, fast, and reproducible way to analyse dose-related data at CT. It allows for automated evaluation of radiation dose in a large study population. Dose exposition is related to the patient's BMI and is increased by up to 96% for extremely obese patients undergoing abdominal CT.