Purpose or Case Report: Determine the most effective method of computed tomography (CT) dose reduction that maintains diagnostic imaging quality, relative to individual patient size characteristics, such as Body Mass Index (BMI) and maximal girth.
Methods & Materials: The Carilion Clinic PACS system was queried by using CPT codes for body CT, chest, abdomen, and pelvis, patient age range 2-18 at the time of CT scan acquisition from 2008-2014. The data set was cross referenced with the electronic medical record for patient BMI and subsequently analyzed. Variables from CT dosage reports were extracted for each individual scan, including Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP). Images from individual scans were measured to calculate patient girth and cross-sectional area. Raw data was analyzed using JMP 11 statistical software. Radiation dose for iterative reconstruction, mA reduction, and kVp reduction based on BMI was compared to dose for traditional CT relative to patient BMI and girth.
Results: The Epic query yielded 1330 unique CT scans, including data of date of CT scan, patient age at time of scan, gender, race, height, weight, and BMI. Each of these scans utilized a specific combination of dose reduction technologies, or lack thereof, yielding 4 groups. Using a Weighted Least Squares analysis, the vast majority of CT scans for individual anatomical regions demonstrated no significant difference in radiation exposure relative to dose reduction technology utilized compared to traditional CT without dose reduction. This analysis accounted for increasing patient girth across increasing DLP.
Conclusions: This data suggests that patient size characteristics cannot be used as a predictive factor to select the type of dose reduction technology that would yield the least radiation exposure to an individual patient.