Can Patient’s Body Weight Represent Body Diameter for Pediatric Size-Specific Dose Estimate in Thoracic and Abdominal Computed Tomography?

OBJECTIVE: The objective of the study was to determine whether body weight (BW) can be substituted for body diameters to calculate size-specific dose estimate (SSDE) in the children. MATERIALS AND METHODS: A total of 196 torso computed tomography (CT) studies were retrospectively reviewed. Anteroposterior diameter (D(AP)) and lateral diameter (D(lat)) were measured, and D(AP)+D(lat), effective diameter, SSDE diameter and SSDE(BW) were calculated. Correlation coefficients among body diameters, all SSDE types and percentage changes between CT dose index volumes and SSDEs were analyzed by BW and age subgroups. RESULTS: Overall BW was more strongly correlated with body diameter (r = 0.919–0.960, P < 0.001) than was overall age (r = 0.852–0.898, P < 0.001). The relationship between CT dose index volume and each of the SSDE types (r = 0.934–0.953, P < 0.001), between SSDE(BW) and all SSDE diameters (r = 0.934–0.953, P < 0.001), and among SSDE diameters (r = 0.950–0.989, P < 0.001) overall had strong correlations with statistical significance. The lowest magnitude difference was SSDE(BW)−SSDE(eff). CONCLUSION: BW can be used instead of body diameter to calculate all SSDE types, with our suggested best accuracy for SSDE(eff) and the least variation in age < four years and BW < 20 kg. KEY MESSAGES: Size-specific dose estimate (SSDE) is a new and accurate dose-estimating parameter for the individual patient which is based on the actual size or body diameter of the patient. BW can be an important alternative for all body diameters to estimate size-specific dose or calculate SSDE in children.