Optimisation of patient doses in programmable dental panoramic radiography

Objectives: To estimate the radiation-related risk; associated with twelve imaging programs available on the Orthophos(R) (Siemens, Erlangen, Germany) dental panoramic radiography unit. Methods: Organ absorbed doses for each program were measured using a Rando anthropomorphic phantom loaded with thermoluminescent dosemeters. Effective dose (E) was calculated in two ways; first, using the method recommended by the International Commission on Radiological Protection, which excludes the salivary glands (designated E-exc), and second, with its inclusion (designated E-inc). Organ and effective doses were both used to compare the various imaging programs. Results: In 11 of the 12 programs studied the salivary glands received the highest individual organ dose, and E-inc was found to be up to double E-exc. When the image was restricted to the dentition (program 2) organ doses were lower than for the complete jaws (program 1) by up to 85%, and E-exc and E-inc reduced by about one half. When programs 2 and 6 (to image the temporomandibular joints) are used in place of program 1, the former combination provides more image information at an equivalent risk. Conclusions: The value of E in panoramic radiography depends on the inclusion of the salivary glands in the calculation and the magnitude of the dose.