Chest
Special FeaturesRadiation Risks in Lung Cancer Screening Programs
Section snippets
Materials and Methods
The NLST was used as the primary lung cancer screening reference because recommendations for screening by the American College of Chest Physicians and the American Society of Clinical Oncology have been based on this study.2, 3 Participants were aged 55 to 74 years, had a ≥ 30-pack-year smoking history, and were current smokers or former smokers who quit in the past 15 years.
Screenings yielding noncalcified nodules > 4 mm necessitated diagnostic follow-up, with full CT scan initially. The size
Assumptions on the Prevalence and Incidence of Nodules Detected in Lung Cancer Screening
Up to 50% of smokers aged > 50 years have pulmonary nodules.11, 13 A significant heterogeneity has been noted in the percentage of nodules detected at incidence and prevalence in lung cancer screening programs. We chose to use the range of 25% to 50% for both incidence and prevalence of nodules detected on LDCT scan on the basis of several studies.2, 3, 6, 8, 9 Incidence of nonpulmonary conditions warranting follow-up averaged about 5% in lung cancer screening programs.9
Radiation Doses From LDCT Scanning and CT Scanning
Radiation exposure is measured by a number of units, including sieverts and grays. The sievert reflects the effective dose and represents the stochastic biologic effects of ionizing radiation. One sievert equals 100 rem (roentgen equivalent man), an older radiation metric. The gray is the radiation measure used to reflect the absorbed dose.
In the NLST, the estimated effective doses of LDCT and CT scans were 2 mSv and 7 to 8 mSv, respectively; about 10% of the LDCT scans were associated with
Assessing Risk of Occupational Radiation Exposure
We addressed chronic low-dose radiation risks by reviewing nuclear worker cohort studies in which the risk of lung cancer was evaluated in light of total ionizing radiation exposure. We also used atomic bomb survivor data to assess acute high-dose radiation exposure risk.
Determining Cumulative Dose of Ionizing Radiation in Lung Cancer Screening Programs
Different scenarios were used to estimate the cumulative radiation exposure from screening over 20- to 30-year periods. The primary variables were (1) percentage of nodules detected on LDCT scan requiring follow-up, (2) radiation doses associated with screening and diagnostic studies, and (3) length of the screening program (20 vs 30 years). We considered 30 years as reflective of starting screening at age 50 and stopping at age 80. These assumptions were made to simplify the estimation of
Estimating Cumulative Radiation Exposure From Lung Cancer Screening Programs
If a 4-mm nodule is detected per LDCT scan, an additional three CT scans are recommended before concluding that the nodule is benign. These additional full CT scans per 4-mm nodule detected add another 24 mSv of radiation exposure. If a 4-mm nodule is detected every 2 years, the cumulative radiation exposure would be 2 mSv per year over 20 years (40 mSv) for the LDCT scans and 24 mSv per follow-up for each 4-mm nodule detected. Thus, over a 20-year period (ages 55-75 years), the cumulative
Conclusions
Of the 90 million current and former smokers in the United States, about 8 to 8.7 million adults meet the NLST criteria for lung cancer screening with LDCT scan.3, 30, 31, 32 Thus, lung cancer screening may involve a substantial number of people, which makes clarifying the risks and benefits of screening of paramount importance.
We evaluated cumulative radiation doses for lung cancer screening participants from the LDCT scan to follow-up full CT scan and FNAB according to the incidence and
Acknowledgments
Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
References (40)
- et al.
Radiation and chest CT scan examinations: what do we know?
Chest
(2012) Radiation and chest CT scans: are there problems? What should we do?
Chest
(2012)- et al.
The solitary pulmonary nodule
Chest
(2003) - et al.
Prevalence of small lung opacities in populations unexposed to dusts. A literature analysis
Chest
(1997) - et al.
What to do when a smoker's CT scan is “normal”? Implications for lung cancer screening
Chest
(2012) - et al.
Lung cancer: diagnosis and management
Am Fam Physician
(2007) - et al.
Reduced lung-cancer mortality with low-dose computed tomographic screening
N Engl J Med
(2011) - et al.
Benefits and harms of CT screening for lung cancer: a systematic review
JAMA
(2012) - et al.
ACP Journal Club. Review: CT screening for lung cancer reduced mortality in 1 large trial but not in 2 smaller trials
Ann Intern Med
(2012) - et al.
When the average applies to no one: personalized decision making about potential benefits of lung cancer screening
Ann Intern Med
(2012)
CT scan screening for lung cancer: risk factors for nodules and malignancy in a high-risk urban cohort
PLoS ONE
Diagnostic accuracy and complication rate of CT-guided fine needle aspiration biopsy of lung lesions: a study based on the experience of the cytopathologist
Acta Radiol
The 15-country collaborative study of cancer risk among radiation workers in the nuclear industry: estimates of radiation-related cancer risks
Radiat Res
Guidelines for management of small pulmonary nodules detected on CT scans: a statement from the Fleischner Society
Radiology
Estimated radiation dose associated with low-dose chest CT of average-size participants in the National Lung Screening Trial
AJR Am J Roentgenol
Radiation risks potentially associated with low-dose CT screening of adult smokers for lung cancer
Radiology
Recurrent CT, cumulative radiation exposure, and associated radiation-induced cancer risks from CT of adults
Radiology
Effective doses in radiology and diagnostic nuclear medicine: a catalog
Radiology
Dose exposure in the ITALUNG trial of lung cancer screening with low-dose CT
Br J Radiol
Radiation in the workplace-a review of studies of the risks of occupational exposure to radiation
J Radiol Prot
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