Reference phantom selection in pediatric computed tomography using data from a large, multicenter registry

Philip W Chu; Sophronia Yu; Yifei Wang; J Anthony Seibert; Luisa F Cervantes; Nima Kasraie; Cameron A Chu; Rebecca Smith-Bindman

doi:10.1007/s00247-021-05227-0

Reference phantom selection in pediatric computed tomography using data from a large, multicenter registry

Pediatr Radiol. 2022 Mar;52(3):445-452. doi: 10.1007/s00247-021-05227-0. Epub 2021 Dec 6.

Authors

Philip W Chu¹, Sophronia Yu², Yifei Wang¹, J Anthony Seibert³, Luisa F Cervantes⁴, Nima Kasraie⁵, Cameron A Chu¹, Rebecca Smith-Bindman^{6

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Affiliations

¹ Department of Epidemiology & Biostatistics, University of California San Francisco, 550 16th St., Box 0560, San Francisco, CA, 94143, USA.
² Chan Zuckerberg Biohub, San Francisco, CA, USA.
³ Department of Radiology, University of California Davis Health, Sacramento, CA, USA.
⁴ Department of Radiology, Nicklaus Children's Hospital, Miami, FL, USA.
⁵ Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA.
⁶ Department of Epidemiology & Biostatistics, University of California San Francisco, 550 16th St., Box 0560, San Francisco, CA, 94143, USA. Rebecca.Smith-Bindman@ucsf.edu.
⁷ Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, CA, USA. Rebecca.Smith-Bindman@ucsf.edu.
⁸ Philip R. Lee Institute for Health Policy Studies, University of California San Francisco, San Francisco, CA, USA. Rebecca.Smith-Bindman@ucsf.edu.

Abstract

Background: Radiation dose metrics vary by the calibration reference phantom used to report doses. By convention, 16-cm diameter cylindrical polymethyl-methacyrlate phantoms are used for head imaging and 32-cm diameter phantoms are used for body imaging in adults. Actual usage patterns in children remain under-documented.

Objective: This study uses the University of California San Francisco International CT Dose Registry to describe phantom selection in children by patient age, body region and scanner manufacturer, and the consequent impact on radiation doses.

Materials and methods: For 106,837 pediatric computed tomography (CT) exams collected between Jan. 1, 2015, and Nov. 2, 2020, in children up to 17 years of age from 118 hospitals and imaging facilities, we describe reference phantom use patterns by body region, age and manufacturer, and median and 75th-percentile dose-length product (DLP) and volume CT dose index (CTDI_vol) doses when using 16-cm vs. 32-cm phantoms.

Results: There was relatively consistent phantom selection by body region. Overall, 98.0% of brain and skull examinations referenced 16-cm phantoms, and 95.7% of chest, 94.4% of abdomen and 100% of cervical-spine examinations referenced 32-cm phantoms. Only GE deviated from this practice, reporting chest and abdomen scans using 16-cm phantoms with some frequency in children up to 10 years of age. DLP and CTDI_vol values from 16-cm phantom-referenced scans were 2-3 times higher than 32-cm phantom-referenced scans.

Conclusion: REFERENCE PHANTOM SELECTION IS HIGHLY CONSISTENT, WITH A SMALL BUT SIGNIFICANT NUMBER OF ABDOMEN AND CHEST SCANS (~5%) USING 16-CM PHANTOMS IN YOUNGER CHILDREN, WHICH PRODUCES DLP VALUES APPROXIMATELY TWICE AS HIGH AS EXAMS REFERENCED TO 32-CM PHANTOMS.

Keywords: Children; Computed tomography; Phantom; Radiation dose; Reference phantom; Registry.

Publication types

Multicenter Study

MeSH terms

Adult
Child
Humans
Phantoms, Imaging
Radiation Dosage
Registries
Thorax*
Tomography, X-Ray Computed* / methods