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National Lung Screening Trial

NLST Staff Photo

The Role of ERL

The National Lung Screening Trial (NLST) aims to compare the effectiveness of two screening tests, low-dose spiral CT scan and chest x-ray (CXR), in net lung cancer-specific mortality in persons who are at high risk (histories of heavy smoking, but no lung cancer) for developing lung cancer.  The trial is sponsored by the National Cancer Institute (NCI) and conducted under a harmonized protocol within two separate administrative organizations: the Lung Screening Study (LSS) and the American College of Radiology Imaging Network (ACRIN).  Accrual through 10 LSS screening centers (SCs) is complete with 34,614 participants enrolled over the period September 2002 through May 2004.    LSS SCs operate within the screening centers of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial Network.

Participants were randomized to chest Xray or CT imaging arms, and three serial screening exams {T0, T1, T2} were performed at annual intervals.  Images were interpreted and stored locally at the SCs. Screening results, participant demographic and baseline health data, and medical follow-up information were forwarded to Westat, an independent research firm, contracted by NCI to coordinate the LSS network.  Screening completed early 2007.

The Electronic Radiology Lab (ERL) of the Mallinckrodt Institute of Radiology, Washington University School of Medicine, manages the imaging Quality Assurance Coordinating Center (QACC) for the LSS network of the NLST.   Each month, Westat provides a list of some 4-5% of the previous month’s CT and digital chest X-ray exams to the SCs and the ERL.  The SCs transmit these exams over a secure Internet Virtual Private Network.  The exams are posted on an image server accessed by NLST QA-radiologists who assess the exams for image quality.  For exams of poor diagnostic quality, SCs are asked to repeat.

In late 2004, NCI contracted the ERL to collect the 3 screens of 17,308 participants randomized to the CT arm (possible total 51,924 exams) as a lung-imaging-research resource.  A CT Image Library (CTIL) infrastructure was organized, and collection began in 2005, more than two years after initial screenings.  All exams were expected to be de-identified and delivered to the CTIL by March, 2007, via DVD, external hard drive (XHD), or secure Internet transmission and could be delivered in any order {T0, T1, T2} suiting local SC workflow.  Periodic delivery quotas were not imposed.  The DICOM headers of delivered exams are inspected to make sure they meet NLST-protocol specifications, and images are inspected to make sure they are uncorrupted, have adequate lung coverage, and contain no protected health information.  The size of the CTIL is about 7 terabytes.


The Mallinckrodt Institute of Radiology is a screening center for LSS and, thus, within the Washington University screening center of the PLCO.  David Gierada, M.D., an ERL collaborator, is the Principal Investigator of the LSS screening center, the QACC, and the CTIL.


National Cancer Institute Contract N01-CN-25516



  1. Moore SM, Gierada DS, Clark KW, Blaine GJ, and the PLCO-NLST Quality Assurance Working Group, “Image Quality Assurance in the Prostate, Lung, Colon, and Ovarian (PLCO) Cancer Screening Trial Network of the National Lung Screening Trial” (Poster Session, SCAR 2004), J Digit Imaging 18(3):242-250, 2005.
  2. K. W. Clark, D. S. Gierada, S. M. Moore, D. R. Maffitt, P. Koppel, S. R. Phillips, F. W. Prior, Creation of a CT Image Library for the Lung Screening Study of the National Lung Screening Trial, Journal of Digital Imaging, Jan 2006, , DOI 10.1007/s10278-006-0589-5, URL http://dx.doi.org/10.1007/s10278-006-0589-5
  3. http://www.mir.wustl.edu/graphics/assets/media/