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NLST CT Images

The NLST low-dose helical CT scan image collection comes from over 25,000 people who were randomly assigned to the CT arm of NLST. The CT arm protocol was for three annual helical CT exams to screen for lung cancer: one at baseline (T0) and two more on the first and second anniversaries of randomization (T1 and T2). Only images from CT screening exams are available; images from follow-up scans (with higher radiation dose and image quality) are not in the collection. For each screening exam, the image collection contains (on average) one localizer image and 2 to 3 axial reconstructions of a single helical CT scan of the chest. Approximately 200,000 image series from 75,000 CT exams in 25,000 people are available.

CT images do not contain radiologist’s findings. Findings detected in trial screening can be found in the Spiral CT Abnormalities or Spiral CT Comparison Read Abnormalities datasets. Coordinates of findings on CT screens were not collected by the NLST trial.

The complete collection of CT images is comprised of more than 20 million files requiring over 10TB.

Group Participants Localizer Images Axial Images Terabytes
Screen Detected Lung Cancer with Image in Same Study Year 622 1,035 2,244 0.17
Lung Cancer with Image 436 1,000 2,104 0.16
Nodule positive or screen positive with image in Same Study Year 9,470 24,483 56,423 3.91
3 Negative Screens with 3 Images 12,548 34,452 65,197 4.85
Other Participants 3,162 4,206 10,493 0.96

NLST Pathology Images

The NLST pathology images come from ~450 lung cancer patients in the Lung Screening Study (LSS) subcomponent of NLST. They are images of H&E-stained slides that were obtained as part of a pathology specimen collection to construct tissue microarrays (TMAs). The ~1250 H&E slides (and corresponding images) each came from blocks of lung tissue that were resected during diagnosis and treatment of lung cancer and preserved by pathology labs.

A pathologist reviewed each image to identify histologies of interest for tissue sampling and inclusion in the TMAs. Each region of interest (ROI) was digitally annotated, and the histologies were recorded on case report forms. Data from the case report forms may be obtained by investigators. Annotated pathology images were not retained and are therefore not available.

Image Access

The following options for NLST image access are now available:

  • Cancer Data Access System (CDAS) – All CT and Pathology images are available by hard drive shipment. If you would like to ship a hard drive and pay for the return shipping back to you then submit a request and we will contact you with details. If you have any questions please post at
  • Imaging Data Commons (IDC) – All CT and Pathology images may be viewed online by registering an account and logging in. Questions related to the use of this service should be directed to
  • The Cancer Imaging Archive (TCIA) – All CT and Pathology images may be downloaded. CT images are available in whole or in batches of 2,500 participants each. Questions related to the use of this service should be directed to