Use of PET/CT instead of CT-only when planning for radiation therapy does not notably increase life years lost in children being treated for cancer.
BACKGROUND
PET/CT may be more helpful than CT alone for radiation therapy planning, but the added risk due to higher doses of ionizing radiation is unknown.


OBJECTIVE
To estimate the risk of cancer induction and mortality attributable to the [F-18]2-fluoro-2-deoxyglucose (FDG) PET and CT scans used for radiation therapy planning in children with cancer, and compare to the risks attributable to the cancer treatment.


METHODS
Organ doses and effective doses were estimated for 40 children (2-18 years old) who had been scanned using PET/CT as part of radiation therapy planning. The risk of inducing secondary cancer was estimated using the models in BEIR VII. The prognosis of an induced cancer was taken into account and the reduction in life expectancy, in terms of life years lost, was estimated for the diagnostics and compared to the life years lost attributable to the therapy. Multivariate linear regression was performed to find predictors for a high contribution to life years lost from the radiation therapy planning diagnostics.


RESULTS
The mean contribution from PET to the effective dose from one PET/CT scan was 24% (range: 7-64%). The average proportion of life years lost attributable to the nuclear medicine dose component from one PET/CT scan was 15% (range: 3-41%). The ratio of life years lost from the radiation therapy planning PET/CT scans and that of the cancer treatment was on average 0.02 (range: 0.01-0.09). Female gender was associated with increased life years lost from the scans (P < 0.001).


CONCLUSIONS
Using FDG-PET/CT instead of CT only when defining the target volumes for radiation therapy of children with cancer does not notably increase the number of life years lost attributable to diagnostic examinations.
Section of Radiotherapy, Department of Oncology, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark, josefine.staahl.kornerup@regionh.dk.
Josefine S
JS
Kornerup
Patrik
P
Brodin
Charlotte
C
Birk Christensen
Thomas
T
Björk-Eriksson
Anne
A
Kiil-Berthelsen
Lise
L
Borgwardt
Per
P
Munck Af Rosenschöld
D000293:Adolescent; D001943:Breast Neoplasms / Q000401:mortality* / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008017:Life Expectancy; D008297:Male; D064847:Multimodal Imaging / Q000706:statistics & numerical data; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D015995:Prevalence; D011379:Prognosis; D019057:Quality-Adjusted Life Years; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D055815:Young Adult