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.

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: Single photon emission computed tomography (SPECT) imaging is widely implemented in nuclear medicine for detecting coronary artery diseases. To increase the accuracy of the diagnosis, it is necessary to improve the quality of the SPECT images that can be degraded by noise. The aim of this study was to evaluate the effectiveness of using different filters such as Butterworth, Gaussian, Wiener with kernel sizes 3×3 and 5×5, and Median Modified Wiener Filters (MMWF with kernel sizes 3×3 and 5×5 to improve the quality of myocardial perfusion SPECT images with 99mTc-MIBI. Methods: A Siemens Symbia T2 dual head SPECT/CT scanner equipped with a low-energy and high-resolution collimator (LEHR) was used for collecting data for this cross-sectional-applied study. The noise ratio (SNR), peak to noise ratio (PSNR) and contrast to noise ratio (CNR) were the indices used to asses the quality of the myocardial perfusion SPECT images of 30 patients after the filters mentioned above have been applied to the images. Findings: Wiener filter with kernel size of 5×5 4. 90 ±,0. 69 and 2. 65 ±,0. 57 were found be the highest SNR and CNR indices respectively. However, it had the lowest PSNR in the range of 29. 93 ±,3. 13 (dB). In addition, the highest PSNR values were associated with the Gaussian filter as 50. 09 ±,10. 63 (dB). Conclusion: The results of this study show that the wiener filter of kernel size of 5×5 outperformed the others to improve the quality of myocardial perfusion SPECT images used in this study.

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.

Documented evidences available from both developed and developing countries reveal that the number of clinical imaging procedures and instruments have continued to increase over the past decades, confirming the increasing demand for these clinical imaging modalities. Accordingly, concerns about over-utilization and inappropriate use in imaging have been raised, and consequently medical authorities and clinicians who were slow to respond to spiraling costs of cardiac imaging years ago, now recognize the need to promote appropriate and cost-conscious use of imaging, mainly through the development of appropriateness criteria and guidelines, which are focused on eliminating unnecessary testing to decrease health care costs.

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.