Estimation of cancer mortality associated with repetitive computed tomography scanning.
BACKGROUND
Low-dose radiation from computed tomography (CT) may increase the risk of certain cancers, especially in children.


OBJECTIVE
We sought to estimate the excess all-cause and cancer-specific mortality, which may be associated with repeated CT scanning of patients with cystic fibrosis (CF).


METHODS
The radiation dose was calculated for a published CF surveillance CT scanning protocol of biennial CT scans, and the risk per scan was estimated using atom-bomb survivor data. A computational model was developed to calculate the excess mortality in a CF cohort associated with radiation from the CT scan and to evaluate the effects of background survival, scanning interval, and level of CT radiation used. The model assumed that there would be no survival benefits associated with repeated surveillance CT scanning.


RESULTS
The average radiation dose for the published CT protocol was 1 mSv. Survival reduction associated with annual scans from age 2 yr until death was approximately 1 mo and 2 yr for CF cohorts, with a median survival of 26 and 50 yr, respectively. Corresponding cumulative cancer mortality was approximately 2 and 13% at age 40 and 65 yr, respectively. Biennial CT scanning reduced all-cause and cumulative cancer mortality by half.


CONCLUSIONS
Routine lifelong annual CT scans carry a low risk of radiation-induced mortality in CF. However, as the overall survival increases for patients with CF, the risk of radiation-induced mortality may modestly increase. These data indicate that radiation dose must be considered in routine CT imaging strategies for patients with CF, to ensure that benefits outweigh the risks.
de Jong
Pim A
PA
Department of Pediatric Pulmonology and Allergology, Erasmus MC-Sophia Children's Hospital, Dr Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands. pdejong@mrl.ubc.ca
Mayo
John R
JR
Golmohammadi
Kamran
K
Nakano
Yasutaka
Y
Lequin
Maarten H
MH
Tiddens
Harm A W M
HA
Aldrich
John
J
Coxson
Harvey O
HO
Sin
Don D
DD
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003198:Computer Simulation; D003550:Cystic Fibrosis / Q000000981:diagnostic imaging; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology / Q000401:mortality*; D011829:Radiation Dosage; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000009:adverse effects*