Background: Multislice Computed Tomography (CT) angiography is a robust imaging method for noninvasive assessment of coronary artery diseases، which is associated with high radiation dose. Having knowledge of the various parameters used to estimate the dose plays an important role in increasing the understanding of dose delivered to patients and help operators and technologist to reduce the dose. In this research، the amounts of Weighted Computed Tomography Dose Index (CTDIW) for coronary CT angiography exams were measured in Isfahan city, IranMethods: To calculate the dose، an ionization chamber (Piranha، X-ray Analyzer، RTI Electronics and Sweden) and acrylic body phantom were used. Common conditions of coronary CT angiography used in two centers were applied for this project. Finally, CTDIW of all the scans were calculated using the related formulation.Findings: The amount of mean CTDIW for calcium score exams in Sina and Alzahra hospitals were 0.468±0.190 and 2.354±0.610 mGy, respectively (P = 0.007); and for coronary CT angiography scans in Sina and Alzahra hospitals were 6.221±1.290 and 5.299±0.840 mGy, respectively (P=0.860).Conclusion: CTDIW for the calcium score was significantly different in the two centers، but there was not significant difference in the two centers for coronary CT angiography scans. In this study، the amount of CTDIW was much lower than the measured in other centers. Since scan parameters have an important effect on the dose value، training and precision of technologist result in dose reduction and patient radiation protection.

Objectives: The present study aimed to calculate the efficiency of bismuth nanoparticles shield to protect the breast in chest Computed Tomography (CT) scan and investigate the alteration of image quality after using the shield. Materials and Methods: Three groups were included in this experimental research in which phantom was scanned without using nano bismuth shield (group 1), using 0. 5 mm nano bismuth shield (group 2), and employing nano bismuth shield with 1 mm thickness (group 3). The polymethyl methacrylate phantom was applied to present the main organ of the chest including the breast and lung. Multi-detector 6-slice CT scan system was utilized for the tests. In addition, the breast radiation dose was measured by ion-chamber which was placed at 12 o’ clock position in the phantom according to dosimetry protocol. Further, chest CT image processing was performed once without shield and once in the presence of 10% nano bismuth shield with different thicknesses. Finally, image quality was compared by adding the shield for correct diagnosis. Tests were repeated three time and data were analyzed by ANOVA. Results: Based on the results, using nano bismuth Shields, breast dose reduced by 7. 2% and 13. 8% for 0. 5 and 1 mm thickness of the shield, respectively. Furthermore, the CT number and noise increased from 121. 3 to 126. 36 HU and from 24. 53 to 28. 1 HU, respectively. Finally, the dose reduction ratio approximately doubled by increasing the thickness from 0. 5 to 1 mm. Conclusions: Generally, nano bismuth Shields have a noticeable potential for reducing the breast dose with the smallest change in the noise.

Background and Objective: The aim of this study was to evaluate the diagnostic ability of CBCT to detect external root resorption.Subjects and Methods: External root resorption defects of different sizes and in different locations were simulated in 60 human mandibular incisors. Cavities simulating root resorption defects of small size (0.3´0.6 mm), medium (1.2´0.6 mm) and large (1.8´0.9 mm) were drilled in the cervical, medial and apical thirds of buccal surfaces. The teeth were divided in random groups and mounted in the mixture of acryle and dryed skull sheep powder. CBCT scan was used to evaluate external root resorption in 180 root thirds by two blinded observer. Statistical analysis was done with Kappa test.Results: Sensitivity of CBCT to detect external root resorption was 89% and the specificity was 99 %.The most defects that was detected were on the medial root thirds and the lowest defects that were detected were on the apical root. The percentage of small defects detection was 80%.Conclusion: CBCT technique is a very good method to evaluate external root resorption with high sensitivity and excellent specificity. It can detect the defects as small as 0.3mm.

BACKGROUND AND OBJECTIVE: Having the correct anatomical points and the size of the pedicle dimension is necessary to minimize neurological complications. Currently, the gold standard for spinal fusion is the use of pedicle screws. In this method, the pedicle screw should be placed in its ideal position. Given the importance of this topic, the present study was performed to determine the dimensions of right and left pedicle by Computed Tomography (CT) scan in three axial, coronal and sagittal planes based on gender in Fars-native ethnic group. METHODS: This cross-sectional study was performed on 40 patients (20 females and 20 males aged 18 – 45 years) from Fars-native ethnic group. The average height for males was 165 to 180 cm and for females between 165 and 175 cm. Healthy vertebrae were selected in people who referred to a CT scan unit with symptoms of spinal pain or trauma. Determination of height, length and width of right and left pedicle of lumbar vertebrae in axial, coronal and sagittal view in 1. 5 mm sections was performed by CT scan. FINDINGS: Mean and standard deviation of height (1. 458± 0. 141), width (0. 788± 0. 173), and length (1. 248± 0. 195) of pedicle in men (based on millimeter) was significantly higher compared to mean and standard deviation of height (1. 268± 0. 140), width (0. 618± 0. 148), and length (1. 08± 0. 174) in women (p<0. 05). CONCLUSION: The results of this study showed that gender affects the dimensions of lumbar vertebral pedicle.

Introduction: The inferior alveolar canal is an important anatomical structure in the field of dentistry implants and cone beam Computed Tomography (CBCT) is an important diagnostic technique. The aim of this study was to evaluate the prevalence of anatomical variations of the mandibular canal observed in CBCT images. Materials & Methods: In this descriptive-analytic study 384 inferior alveolar canals were evaluated in 192 patients, who were referred to the radiology department of Isfahan Azad University in 1396 for a cone-beam Computed Tomography. Radiographs were performed to assess the frequency of different left and right mandibular canal segregations by sex in terms of upper and lower position, baccolingual position, shape of the general canal. The frequency and different types of existing mandibular plug canals were also evaluated. Data were analyzed by Chi Square, independent T Test, paired t-test. (p value < 0. 05). Results: The mandibular canal was 2. 1% of the lower position, 11. 9% of the upper position and 86% of the middle position. Statistically significant differences were observed between the frequency distributions of canal positions and gender (p value = 0. 004). The prevalence of Bifid mandibular canals was 14. 8%. There was no significant relationship between the shape of the general channel path and gender. There was no significant difference between the mean distance between the mandibular canal and the buccal cortex in both Molar and Ramus with the sex of the subjects and the side of the canal (p value < 0. 05). Conclusion: The highest frequency of mandibular canal in most subjects was on the right in the intermediate position. The mean distance between mandibular canal and buccal cortex in Ramos and Molars area on both right and left sides was not significantly different between men and women.

Introduction & Objective: The mental foramen is a part of lower jaw which has neurovascular bundles and also is important in biology. 3D imaging of this area by cone beam Computed Tomography (CBCT) before surgery can prevent some problems. This study aims to evaluate the anatomic position and geometrical shape of the mental foramen by CBCT images.Materials & Methods: In this research, the CBCT images (by NewTom and Planmeca promax 3D set) of 85 patients referred to dentistry school clinic or other clinics in Hamadan city were studied. These patients did not have their first and second premolar teeth extracted in both right and left sides. The geometrical shape of mental foramen, the canal angle connecting to mental foramen compared to the buccal plate of lower jaw, distance from the lower border of mental foramen to the lower border of lower jaw, position of mental foramen relating to the root of adjacent tooth and the incidence of accessory mental foramen were studied.Results: The means of canal angle connecting to mental foramen in the right side in men and women were 123.3 and 130.1 and in the left side were 123.8 and 133.7, respectively. The mean distance from the lower border of mental foramen to the lower border of lower jaw in the right side in men and women were: 12.4 and 13.3 mm and in the left side were: 12.7 and 13.6 mm, respectively. Also, there is a meaningful statistical relation between gender and the angle of canal of mental foramen, regarding to the buccal plate in both sides.Conclusion: Regarding to the variations in the position and shape of mental foramen and the angle connecting to the mental foramen related to the buccal plate and accessory mental foramen, investigation of CBCT images before placement of implants is necessary.

Background and Objective: Many surgeries are performed on anterior region of mandible. Incisive branch of the inferior alveolar nerve is located in the anterior region of mandible. The identification of various form of nerve is important for diagnosis and treatment plan. This study was carried out to the assessment of visibility and extension rate of incisive branch of the inferior alveolar nerve in cone beam Computed Tomography (CBCT) imagings.Methods: This descriptive- analytic study was performed on 105 CBCT images. The presences or absence of incisive branch of the inferior alveolar nerve and assessment of visibility and extension rate of mandibular incisive canal were studied.Results: In 79% extension of the incisive branch of the inferior alveolar nerve were observed. 18.07% of extensions were observed in one-side and 78.31% were bilateral. Extension of the incisive branch of the inferior alveolar nerve was observed to central, lateral and canine tooth in 59%, 26.5% and 14.5% respectively. There was no significant relation beween gender and age of subjects with extension of the incisive branch of the inferior alveolar nerve.Conclusion: Regarding the high visibility of the incisive nerve branches in the lower dental CBCT images this method can be used to evaluate the anterior region of mandible.