Influence of Body Mass Index and Abdominal Circumference on Radiation Dose During Abdominopelvic Computed Tomography

Background: Contrast-enhanced examinations of the abdomen region have a greater radiation exposure due to the multiphase abdominal computed tomography (CT) protocols. The use of automatic tube current modulation is known to reduce radiation dose and maintain or improve image quality for abdominal CT. However, using automatic tube current modulation can increase radiation dose for individuals with a larger body habitus. Objectives: The study aimed to assess the influence of body mass index and abdominal circumference on the effective dose for routinely performed contrast-enhanced abdomen and pelvis scans. Methods: A total of 160 subjects referred for routine CT abdomen and pelvis were included in the study and categorised into three groups according to their body mass index (BMI) [underweight: <18.5 kg/m2, normal: 18.5-24.9 kg/m2, overweight: 25-29.9 kg/m2 and obese: (≥30 kg/m2]. All the scans were performed on a 128 MDCT scanner by Philips. The effective dose was calculated from the dose length product using region-specific conversion factors. Results: The effective dose was found to be 21.47 ± 2 mSv for the underweight group, 22.75± 2.3 mSv for the normal group, 25.02 ± 2.8 for the overweight group, and 29.7 ± 6.7 mSv for the obese group. Conclusion: The study reported a 32.39 % increase in effective dose for obese patients. The study also reported a significant increase in effective dose as BMI and abdominal circumference increased.