Effective dose equivalent and effective dose: Comparison for common projections in oral and maxillofacial radiology

Objectives. Effective dose equivalents (H-E) and effective doses (E) for radiographic projections common in dentistry, calculated from the same organ dose distributions, are presented to determine whether the 2 quantities can be directly compared. Study design. Doses to all organs and tissues in the head, neck, trunk. and proximal extremities were determined for each projection (intraoral full-mouth radiographic survey, panoramic, cephalometric, temporomandibular tomograms, and submentovertex view) by computer simulation with Monte Carlo methods. H-E and E were calculated from these complete distributions and by methods prescribed by the International Commission on Radiological Protection (ICRP). Results. H-E and E computed from complete dose distributions were found comparable within a few percentage points. However, those computed by strict application of ICRP methods were not. Conclusion. For radiographic projections with highly localized dose distributions, such as those common in dentistry, direct comparison of H-E and E may not be meaningful, unless both computation algorithms are known.