Effective dose equivalent estimates in diagnostic radiology with single dosimetry.

In many external exposure situations dose estimates obtained from personal monitors significantly overestimate the Effective Dose Equivalent (EDE). This occurs particularly when the body is not uniformly exposed due to the irradiation conditions or due to protective shielding (i.e., lead apron) of portions of the body (NCRP 1995). Many numerical relationships between monitoring data and EDE have been proposed to perform more accurate dose estimates (Gill et al. 1980; Faulkner and Harrison 1988; Webster 1989; Niklason et al. 1994; Berger et al. 1995). Also, organizations such as the Conference of Radiation Control Program Directors (CRCPD), the National Council on Radiation Protection and Measurements (NCRP) and the Electric Power Research Institute (EPRI) have published recommendations on this subject (CRCPD 1995; NCRP 1995; EPRI 1998). Before implementing the use of any of the proposed relationships, they should be thoroughly reviewed so that proper practices are chosen and monitoring data are properly evaluated. It is also important for each facility to be aware of the regulatory requirements in their state such as if the methodology is approved for use, which method and for whom can the EDE be applied. The United States Nuclear Regulatory Agency (NRC) does not currently permit dose weighting for any of its licensees. The EPRI study performed in 1997 was initiated by the NRC to determine how viable dose weighting would be, and for which NRC licensee population. This paper discusses numerical relationships for external exposure in diagnostic radiology for estimating EDE in a single-monitor program.