ABSTRACT
PURPOSE: To calculate the effective doses of cone-beam computed tomography (CBCT) using personal computer-based Monte Carlo (PCXMC) software (Radiation and Nuclear Safety Authority, Helsinki, Finland) and to compare the calculated effective doses with those measured using thermoluminescent dosimeters (TLDs) and an anthropomorphic phantom. MATERIALS AND METHODS: An Alphard VEGA CBCT scanner (Asahi Roentgen Ind. Co., Kyoto, Japan) with multiple fields of view (FOVs) was used for this study. The effective doses of the scout and main projections of CBCT using 1 large and 2 medium FOVs with a height >10 cm were calculated using PCXMC and PCXMCRotation software and then were compared with the doses obtained using TLD-100 LiF and an anthropomorphic adult human male phantom. Furthermore, it was described how to determine the reference points on the Y- and Z-axes in PCXMC, the important dose-determining factors in this software. RESULTS: The effective doses at CBCT for 1 large (20.0 cm×17.9 cm) and 2 medium FOVs (15.4 cm×15.4 cm and 10.2 cm×10.2 cm) calculated by the PCXMC software were 181, 300, and 158 µSv, respectively. These values were comparable (16%–18% smaller) to those obtained through TLD measurements in each mode. CONCLUSION: The use of PCXMC software could be an alternative to the TLD measurement method for effective dose estimation in CBCT with large and medium FOVs.
Subject(s)
Adult , Humans , Male , Cone-Beam Computed Tomography , Methods , Radiation Dosage , Radiation ProtectionABSTRACT
@#Introduction It is important to produce data on the relationship between age and dental degenerative changes in different populations using dental radiography, because the results of the same method could vary according to the population. Aim This study aimed to examine the applicability of the tooth coronal index (TCI) and the pulp/tooth area ratio of the whole tooth (PTR) to develop a population-specific method to accurately estimate the age of Korean adults using digital panoramic radiography. Result The upper and lower canines, as well as the lower first and second premolars of 101 digital panoramic images of Korean adults aged between 20 and 75 years were analyzed. According to the method of Ikeda et al., the height of the crown and the height of the coronal pulp cavity were measured from the cementoenamel junction (CEJ) to the cusp tip and pulp horn; then the TCI was calculated. According to the method of Cameriere et al., the pulp and tooth areas of the whole tooth were measured and the pulp/tooth area ratio (PTR) was calculated. Aside from this, we modified the method such that the whole tooth was divided into the coronal and root parts at the CEJ, with the pulp and tooth areas from the cusp tip to the CEJ designated as the coronal part (PcCR) and from the CEJ to the root apex designated as the root part (PrRR); these parts were measured and their ratios were each calculated. Pearson correlation coefficients, analysis of covariance, linear regression models, and the standard error of the estimate (SEE) were computed using statistical software. To justify the use of linear regression models for purposes of prediction, diagnostic tests of 4 principal assumptions were also performed. The TCI in an individual tooth showed a poor correlation SEE ranging from 14.9 to 15.4 years. The four-tooth combination model slightly improved on these results, with a SEE value of 14.8 years. In an individual tooth, the PTR and PrRR showed better correlation than TCI, with SEE ranging from 10.7 to 13.9 years and from 10.5 to 13.7 years, respectively. The PTR and PrRR of the lower second premolar were the most accurate of the regression models. The PTR and PrRR in a four-tooth combination model showed the best age correlation, with SEE values of 10.5 and 9.8 years, separately. Conclusion TCI is not thought to be an appropriate method to predict the age of Korean adults. However, PTR in the lower second premolar can be used as an appropriate indicator for age prediction, and PrRR is more accurate than PTR in Korean adults.
