Important to the committee’s task and many times reiterated is the need for a source of information on medical diagnostic procedures that use radiation, especially those that use high doses such as CT scans. The main data source for aggregate counts on medical diagnostic procedures that involve radiation by body part is IMV19 IMV is a market research and database provider founded in 1977 which, using a variety of survey methods, tracks diagnostic medical procedures. While IMV surveys have high participation rates and cover a large number of imaging facilities (IMV data were the main source for the NCRP Report 160 [NCRP, 2009]), they do not have a detailed categorization of procedures and therefore are unable to capture the variation in radiation doses and protocols. Detailed data on counts of procedures for large populations are also available from administrative claims such as Medicare. However, information is restricted to those that are age 65 or over and use this social insurance program. Neither IMV nor Medicare data are directly applicable for the present task, as they do not contain information about medical diagnostic imaging at the census-tract level.

4.4 FINDINGS AND RECOMMENDATIONS

This chapter provides the committee’s assessment of methodological approaches for carrying out a cancer epidemiology study. Based on this assessment, the committee finds that:

  1. The statistical power of an epidemiologic study of cancer risks in populations near nuclear facilities is likely to be low because (a) the size of the estimated risks from the reported radioactive effluent releases from nuclear facilities is likely to be small and (b) the size of the populations most likely to be exposed (that is, those in close proximity to a nuclear facility, for example, within an 8-km radius) is relatively small. This implies that a large-scale multisite study with as many years of observations as possible is needed to reliably assess the potential risks.
  2. Centralized cancer registries such as SEER and NPCR (for cancer incidence) or national offices such as NCHS (for cancer mortality) can only release data that are aggregated across geographic areas such as counties. Cancer incidence and mortality data for more refined geographic areas can be released only by individual states upon submission and approval of a research proposal. In general, cancer mortality data are available since about 1970, but individual address at time of death is not captured until much


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