National Lung Screening Trial (NLST) Screening

Inclusion Criteria:

* Age 55-74 years (pack-years = packs per day \* years smoked)
* 30 or more pack-years of cigarette smoking history
* Former smokers: quit smoking within the previous 15 years
* Ability to lie on the back with arms raised over the head
* Signed informed consent form

Exclusion Criteria:

* Metallic implants or devices in the chest or back, such as pacemakers or Harrington fixation rods
* Treatment for, or evidence of, any cancer other than nonmelanoma skin cancer or carcinoma in situ (with the exception of transitional cell carcinoma in situ or bladder carcinoma in situ) in the 5 years prior to eligibility assessment
* History of lung cancer
* History of removal of any portion of the lung, excluding needle biopsy
* Requirement for home oxygen supplementation
* Participation in another cancer screening trial
* Participation in a cancer prevention study, other than a smoking cessation study
* Unexplained weight loss of more than 15 pounds in the 12 months prior to eligibility assessment
* Recent hemoptysis
* Pneumonia or acute respiratory infection treated with antibiotics in the 12 weeks prior to eligibility assessment
* Chest CT examination in the 18 months prior to eligibility assessment