Doses to patients from pantomographic and conventional dental radiography.

The increasing popularity of pantographic dental radiography and particularly its recent use for routine screening of asymptomatic patients have prompted the NRPB to compare the risks to patients from this technique with those from more conventional dental diagnostic procedures. Pantographic equipment from seven manufacturers have been investigated along with five procedures for obtaining similar information using conventional dental X-ray sets. Lithium borate thermoluminescent dosimeters located at 141 sites in the head and neck of a Rando phantom have been used to measure the mean absorbed dose to organs of interest as well as the total energy imparted to the phantom. Relative values of the energy imparted by the various techniques provide an estimate of their relative somatic risk to the patient. Pantomographic techniques were generally found to impart less than half the energy to the phantom than that given by a conventional full-mouth periapical series conducted at 45 kV, and a similar amount of energy to four bitewing intra-oral films. The restriction of the frequency of pantomographic examinations to no more than once per year during adolescence and once per three to five years during adulthood has been shown to involve only a minimal increase in the risk of somatic injury to the patient.