Reconstruction of doses from occupationally related medical x-ray examinations.

Many nuclear weapons complex workers were required to undergo medical x-ray examinations as a condition of their employment. To ensure that their dose reconstructions are complete, it is necessary to include the contributions from these examinations. X-ray procedures that must be evaluated include: (1) posterior-anterior and lateral radiography, and/or photofluorography, of the chest; (2) anterior-posterior, lateral and oblique lumbar, cervical and thoracic radiography of the spine; and (3) radiography of the pelvis. Each is discussed in the context of conditions that existed during the time the worker was employed. For purposes of dose reconstruction, the x-ray beam size is especially important because the dose conversion factors (DCFs) for each specific body organ depend on whether it was in, or on the periphery of, the primary beam. The approach adopted was to use the DCFs, combined with the entrance kerma, to estimate the organ doses. In cases in which beam output data or information on the primary factors influencing the dose are not available, methods to provide conservative (i.e., claimant-favorable) entrance kerma and dose estimates are adopted. These include specific default values for chest radiography. To account for uncertainties, the estimated doses due to x-ray examinations are increased by 30%.