title: Automated pediatric abdominal effective diameter measurements versus age-predicted body size for normalization of CT dose.
abstract: There has been increasing interest in adjusting CT radiation dose data for patient body size. A method for automated computation of the abdominal effective diameter of a patient from a CT image has previously only been tested in adult patients. In this work, we tested the method on a set of 128 pediatric patients aged 0.8 to 12.9 years (average 8.0 years, SD = 3.7 years) who had CT abdomen/pelvis exams performed on a Toshiba Aquilion 64 scanner. For this set of patients, age-predicted abdominal effective diameter extrapolated based on data from the International Commission on Radiation Units and Measurements was a relatively poor predictor of measured effective diameter. The mean absolute percentage error between the CTDI normalization coefficient calculated from a manually measured effective diameter and the coefficient determined by age-predicted effective diameter was 12.3 % with respect to a 32 cm phantom (range 0.0-52.8 %, SD 8.7 %) and 12.9 % with respect to a 16 cm phantom (range 0.0-56.4 %, SD 9.2 %). In contrast, there is a close correspondence between the automated and manually measured patient effective diameters, with a mean absolute error of 0.6 cm (error range 0.2-1.3 cm). This correspondence translates into a high degree of correspondence between normalization coefficients determined by automated and manual measurements; the mean absolute percentage error was 2.1 % with respect to a 32 cm phantom (range 0.0-8.1 %, SD = 1.4 %) and 2.3 % with respect to a 16 cm phantom (range 0.0-9.3 %, SD = 1.6 %).
authors.affiliation: Department of Radiology, Keck School of Medicine of USC, Los Angeles, CA, USA, phillip.cheng@usc.edu.
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Cheng
authors.forename: Linda A
authors.initials: LA
authors.lastname: Vachon
authors.forename: Vinay A
authors.initials: VA
authors.lastname: Duddalwar
mesh_terms: D000367:Age Factors; D001331:Automation; D049628:Body Size / Q000528:radiation effects*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D009010:Monte Carlo Method; D010372:Pediatrics; D010388:Pelvis / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000379:methods; D011860:Radiography, Abdominal / Q000379:methods*; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed / Q000009:adverse effects / Q000379:methods*