Dosimetry of digital panoramic imaging. Part I: patient exposure

Objectives: To measure patient radiation dose during panoramic exposure with various panoramic units for digital panoramic imaging. Methods: An anthropomorphic phantom was filled with thermoluminescent dosemeters (TLD 100((R))) and exposed with five different digital panoramic units during ten consecutive exposures. Four machines were equipped with a direct digital CCD (charge coupled device) system, whereas one of the units used storage phosphor plates (indirect digital technique). The exposure settings recommended by the different manufacturers for the particular image and patient size were used: tube potential settings ranged between 64 kV and 74 kV, exposure times between 8.2 s and 19.0 s, at fuse current values between 4 mA and 7 mA. The effective radiation dose was calculated with inclusion of the salivary glands. Results: Effective radiation doses ranged between 4.7 mu Sv and 14.9 mu Sv for one exposure. Salivary glands absorbed the most radiation for all panoramic units. When indirect and direct digital panoramic systems were compared, the effective dose of the indirect digital unit (8.1 mu Sv) could be , found within the range of the effective doses for the direct digital units (4.7- 14.9 mu Sv). Conclusions: A rather wide range of patient radiation doses can be found for digital panoramic units. There is a tendency for lower effective doses for digital compared with analogue panoramic units, reported in previous studies.