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 (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 Eexc), and second, with its inclusion (designated Einc). 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 Einc was found to be up to double Eexc. 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 Eexc and Einc 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.