Abstract
The International Commission on Radiological Protection (ICRP) recommended the use of diagnostic reference levels (DRLs) for optimization of radiation protection of patients, and proposed choosing a percentile point as the initial value of the DRLs in the observed distribution of patient doses. This study was undertaken to survey the distribution of patient doses in our facility and to determine the local DRLs in intraoral radiography for optimization and quality control of dental X-ray examinations.
To obtain the patient entrance doses, background optical densities were measured on the periapical radiograph of adult patient incisors. The total 5,045 radiographs were extracted from the films (Carestream/Kodak UltraSpeed) for diagnostic X-ray examinations performed in the period May/1999-April/2000 using four intraoral X-ray units with half value layers from 1.5 to 2.0mm aluminum and three automatic processors under sensitometric control. The measured optical densities were converted into the patient entrance doses using the film characteristic curve.
The patient entrance doses were observed as a Gaussian distribution for the X-ray examinations of maxillary and mandibular incisors. The average patient entrance doses (±standard deviations) for maxillary and madibular incisors were respectively 1.27 ± 0.25mGy and 1.16 ± 0.24mGy corresponding to the optical densities of 2.59 ± 0.43 and 2.39 ± 0.42.
The average patient entrance doses for maxillary and madibular incisors were nearly equal to the values (1.3mGy and 1.1mGy) of Japan DRLs 2015. The local DRLs, remedial levels, and suspension levels useful for quality control of X-ray examinations were derived from the averages and standard deviations. However, to adequately optimize intraoral radiography, the newer higher sensitivity image receptors should be used for patient doses to achieve the lowest reasonable dose.
