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The Radiation Risk Assessment Tool (RadRAT) is an online calculator for estimating the lifetime risk of cancer incidence for members of the U.S. population (or countries with similar cancer incidence rates) from exposure to ionizing radiation for doses below 1 Gy.

The calculator works using organ-specific dose estimates according to age at exposure and sex. Lifetime total cancer risk and organ-specific risk estimates are reported along with a 90% uncertainty range.

The reported lifetime risks are based on the risk models for the eleven cancers included in the 2006 report of the National Academies of Sciences' BEIR VII Committee and on the risk models for an additional eight cancers, developed by the NCI after the publication of the BEIR VII report. Read more about RadRAT risk models and methodologies.

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RadRAT version 3.7.1 was released in August 2013. Please refer to the upgrade history for the modifications included in various versions of the code.