Risk-benefit analysis of X-ray exposure associated with lung cancer screening in the Italung-CT trial.
OBJECTIVE
Prior analyses of X-ray exposures in lung cancer screening with CT considered the basic acquisition technique in single-detector scanners and the effects of a lifetime screening regimen, whereas the potential benefit in terms of lives saved was not addressed.


METHODS
We determined the total-body effective dose of different acquisition techniques for one single-detector and one MDCT scanner and made projections about the cumulative radiation exposure to smokers undergoing four annual CT examinations on the same scanners in the Italung-CT Trial. Combining these data with estimates of radiation-induced fatal cancer and of the benefit of screening, we calculated the risk-benefit ratio for participants in the trial, ex-smokers, and never-smokers.


RESULTS
The cumulative effective doses per 1,000 subjects were 3.3 Sv using an MDCT scanner and 5.8 or 7.1 Sv using a single-detector scanner. Potential fatal cancers associated with radiation exposure were 0.11 per 1,000 subjects for MDCT scanners and 0.20 or 0.24 for single-detector scanners, which is about 10-100 times lower than the number of expected lives saved by screening assuming a 20-30% lung cancer-specific mortality reduction in current smokers. They were, however, of similar magnitude to the lives saved by screening in never-smokers and former smokers assuming a 10% efficacy of screening.


CONCLUSIONS
MDCT is associated with lower radiation doses than single-detector CT technology. The risk of radiation dose in the Italung-CT Trial is compensated for by the expected benefit. CT screening for lung cancer should not be offered to never-smokers, whereas its recommendation in former smokers is debatable.
Mascalchi
Mario
M
Sezione di Radiodiagnostica, Dipartimento di Fisiopatologia Clinica, Università di Firenze, Viale Morgagni 85, 50134 Firenze, Italia. m.mascalchi@dfc.unifi.it
Belli
Giacomo
G
Zappa
Marco
M
Picozzi
Giulia
G
Falchini
Massimo
M
Della Nave
Riccardo
R
Allescia
Germana
G
Masi
Andrea
A
Pegna
Andrea Lopes
AL
Villari
Natale
N
Paci
Eugenio
E
D000368:Aged; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011829:Radiation Dosage; D018570:Risk Assessment; D012907:Smoking; D014057:Tomography, X-Ray Computed / Q000009:adverse effects*