title: Dose coefficients in pediatric and adult abdominopelvic CT based on 100 patient models.
abstract: Recent studies have shown the feasibility of estimating patient dose from a CT exam using CTDI(vol)-normalized-organ dose (denoted as h), DLP-normalized-effective dose (denoted as k), and DLP-normalized-risk index (denoted as q). However, previous studies were limited to a small number of phantom models. The purpose of this work was to provide dose coefficients (h, k, and q) across a large number of computational models covering a broad range of patient anatomy, age, size percentile, and gender. The study consisted of 100 patient computer models (age range, 0 to 78 y.o.; weight range, 2-180 kg) including 42 pediatric models (age range, 0 to 16 y.o.; weight range, 2-80 kg) and 58 adult models (age range, 18 to 78 y.o.; weight range, 57-180 kg). Multi-detector array CT scanners from two commercial manufacturers (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare) were included. A previously-validated Monte Carlo program was used to simulate organ dose for each patient model and each scanner, from which h, k, and q were derived. The relationships between h, k, and q and patient characteristics (size, age, and gender) were ascertained. The differences in conversion coefficients across the scanners were further characterized. CTDI(vol)-normalized-organ dose (h) showed an exponential decrease with increasing patient size. For organs within the image coverage, the average differences of h across scanners were less than 15%. That value increased to 29% for organs on the periphery or outside the image coverage, and to 8% for distributed organs, respectively. The DLP-normalized-effective dose (k) decreased exponentially with increasing patient size. For a given gender, the DLP-normalized-risk index (q) showed an exponential decrease with both increasing patient size and patient age. The average differences in k and q across scanners were 8% and 10%, respectively. This study demonstrated that the knowledge of patient information and CTDIvol/DLP values may be used to estimate organ dose, effective dose, and risk index in abdominopelvic CT based on the coefficients derived from a large population of pediatric and adult patients.
authors.affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27705, USA. Carl E Ravin Advanced Imaging Laboratories, Duke University, Durham, NC 27705, USA.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Tian
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.forename: W Paul
authors.initials: WP
authors.lastname: Segars
authors.forename: Donald P
authors.initials: DP
authors.lastname: Frush
authors.forename: Erik K
authors.initials: EK
authors.lastname: Paulson
authors.forename: Ehsan
authors.initials: E
authors.lastname: Samei
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D010388:Pelvis / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011860:Radiography, Abdominal; D014057:Tomography, X-Ray Computed; D055815:Young Adult