Estimating population doses from medical radiology

An EU-funded project called DOSE DATAMED has been set up to develop mutually acceptable methods for future surveys of population exposure from medical x-rays, including issuing guidance on suitable patient dose quantities and dosimetry methods. The second report from the project group deals with guidance on how to conduct population dose surveys for medical exposures to improve the comparability of results from various countries. In order to assess population exposures from medical radiology in terms of the collective or per caput effective dose, it is necessary to estimate representative mean effective doses for each type of x-ray examination that makes a significant contribution to the collective dose in a country. Suitable practical dose quantities are entrance surface dose or the dose-area product for simple radiography, the total dose-area product for examinations including fluoroscopy, and the computed tomography dose index and the dose-length product for CT examinations. Factors for converting these practical dose quantities into effective doses are provided in the report. Guidance on assessing the frequency of x-ray examinations includes the definition of 225 specific x-ray examinations and 70 broader categories of examinations, and the identification of those 20 examinations most contributing to the collective effective dose. Information on the age and sex distribution of the patients undergoing these 20 important examinations is provided to assist in relating the collective doses to the collective detriment. Simple approaches for those countries that do not have resources to make comprehensive frequency or dose surveys are provided. The uncertainties involved in various survey methods are addressed. New approaches using dose data stored in the DICOM header and information in the radiological information system (RIS) are also discussed. (author)