[Comparison of absorbed skin dose received by patients in cone beam computed tomography, spiral and conventional computed tomography scanning]

The evaluation of absorbed dose received by patients could give useful information for radiation risk estimation. This study was performed to compare the entrance skin dose received by patients in cone beam computed tomography [CBCT], conventional and spiral computed tomography [CT]. In this experimental study, 81 calibrated TLD chips were used. The TLD chips were placed on facial, thyroid and end of sternum skin surface in patients referred for CT of the paranasal sinuses [3 TLD chips for each area] to estimate the absorbed dose received by central part of radiation field, thyroid and out of field areas, respectively. The data were analyzed using one-way ANOVA and Tukey tests. The dose delivered to the center of irradiated field was about 0.79 +/- 0.09 mGy in CBCT technique compared with 16.31 +/- 3.71 and 18.84 +/- 4.12 mGy for spiral and conventional CT, respectively. The received dose by the out of field areas was about 54 percent of central area dose. There was statistical significant relationship between the imaging modalities and absorbed dose received by patients [P=0.016]. The least absorbed dose was for CBCT and the greatest dose was for conventional CT imaging technique. The dose delivered to central area of irradiated field in conventional and spiral CT imaging modalities was about 24 times greater than of that in CBCT. Also, the highest received dose was for central areas of radiated field and the lowest dose was for the out of field areas

Radiation protection principles observance in Iranian dental schools

In recent decades many guidelines has been conducted by radiation protection organizations about radiation protection in dentistry. This study aimed to evaluate the observance of these guidelines in educational clinics of all dental schools in Iran. In this cross-sectional study a self-administered questionnaire, based on National Radiation Protection Board [NRPB] and European Commission guidelines, was conducted. The radiology departments of all dental school [18 schools] were surveyed in this study. The questionnaire was consisted of 3 sections including intraoral radiography, extraoral radiography and implementation of quality control programs. In the case of the existence of radiation protection facilities [such as lead apron, thyroid shield and lead impacted walls] the use of high speed films and existence of automatic processor in dental schools, there was a proper condition. The main problem was related to lack of regular quality control and quality assurance programs. Digital radiography systems were employed in none of the schools and it was occasionally used for research purposes at some of them. This study has emphasized on the need for further consideration of radiation protection principles in dental schools, especially on the field of quality control and quality assurance programs