Organ Dose and Attributable Cancer Risk in Lung Cancer Screening with Low-Dose Computed Tomography

PLoS One. 2016 May 20;11(5):e0155722. doi: 10.1371/journal.pone.0155722. eCollection 2016.

Abstract

Purpose: Lung cancer screening with CT has been recently recommended for decreasing lung cancer mortality. The radiation dose of CT, however, must be kept as low as reasonably achievable for reducing potential stochastic risks from ionizing radiation. The purpose of this study was to calculate individual patients' lung doses and to estimate cancer risks in low-dose CT (LDCT) in comparison with a standard dose CT (SDCT) protocol.

Materials and methods: This study included 47 adult patients (mean age 63.0 ± 5.7 years) undergoing chest CT on a third-generation dual-source scanner. 23/47 patients (49%) had a non-enhanced chest SDCT, 24 patients (51%) underwent LDCT at 100 kVp with spectral shaping at a dose equivalent to a chest x-ray. 3D-dose distributions were obtained from Monte Carlo simulations for each patient, taking into account their body size and individual CT protocol. Based on the dose distributions, patient-specific lung doses were calculated and relative cancer risk was estimated according to BEIR VII recommendations.

Results: As compared to SDCT, the LDCT protocol allowed for significant organ dose and cancer risk reductions (p<0.001). On average, lung dose was reduced from 7.7 mGy to 0.3 mGy when using LDCT, which was associated with lowering of the cancer risk from 8.6 to 0.35 per 100'000 cases. A strong linear correlation between lung dose and patient effective diameter was found for both protocols (R2 = 0.72 and R2 = 0.75 for SDCT and LDCT, respectively).

Conclusion: Use of a LDCT protocol for chest CT with a dose equivalent to a chest x-ray allows for significant lung dose and cancer risk reduction from ionizing radiation.

MeSH terms

  • Aged
  • Early Detection of Cancer / adverse effects
  • Early Detection of Cancer / methods*
  • Female
  • Humans
  • Lung Neoplasms / diagnosis*
  • Male
  • Middle Aged
  • Monte Carlo Method
  • Radiation Dosage
  • Tomography, X-Ray Computed / adverse effects
  • Tomography, X-Ray Computed / methods*

Grants and funding

The authors have no support or funding to report.