Current status of diagnostic imaging in dental university hospitals in Japan

The diagnostic imaging examinations in all 29 dental university hospitals in Japan were analyzed during a 1-year period from April 1999 to March 2000. The total number of patients examined was 790859, which corresponded to 27271 patients per hospital on average, with a range from 7872 to 62904. Relative to the total number of patients, intraoral radiography was found to have been most frequently performed, 59% on average, with a range from 40% to 80%, depending on the hospital. Extraoral radiography, mostly panoramic radiography, was 36% on average with the range from 18% to 56%.A significant inverse correlation was observed between the percentages of intraoral and extraoral radiography, relative to the total number of all types of imaging examinations. Computed tomography (CT) examinations were performed with their own apparatuses in 27 hospitals with a frequency of 2.9% of patients in all imaging examinations on average and 9.1% at maximum. The scanning parameter of milliampere seconds (mAs) for individual types of routinely performed CT examinations varied widely, and thus the patient dose can be expected to be considerably reduced, without reducing the amount of diagnostic information to be obtained. Other imaging examinations performed were magnetic resonance imaging in 11 hospitals, X-ray fluoroscopy in 8 hospitals, ultrasonography in 20, nuclear medicine in 5, and bone densitometry in 1 hospital.A report from the Radiation Protection Committee (Chairperson, T. Sasaki), Japanese Society for Oral and Maxillofacial Radiology. A portion of this study was presented at the 4th ACOMFR, June 16, 2002, Kaohsiung, Taiwan.