Background and Objectives: Introduction of 64-Slice Multidetector Computed Tomography (MDCT has resulted in a great improvement in the non-invasive coronary artery imaging.Materials and Methods: In a retrospective cross sectional study we evaluated the diagnostic accuracy of 64-Slice MDCT versus invasive coronary angiography in patients with the suspected coronary artery disease who underwent both MDCT and invasive coronary angiography (ICA). Computed tomography angiography and invasive coronary angiography findings of each coronary segment were compared to determine the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of MDCT in the detection of significant lesions (³50% diameter decrease stenosis or total occlusion with no luminal flow shown).Results: a total of 125 patients were evaluated with both methods. In per patient assessment, the sensitivity, specificity, PPV and NPV of MDCT were 97.6%, 85.2%, 95.2% and 92% respectively. These values in per vessel evaluation were 86.3%, 92.2%, 86.8%, and 92.2%, and also corresponding values in per segment evaluation were 69.8%, 94.8%, 69%, and 95% respectively.Conclusion: We concluded that coronary angiography with 64-Slice MDCT has high diagnostic performance for evaluation of significant coronary artery disease (CAD) in patients with the suspected coronary artery disease but cannot replace conventional coronary angiography at present time.

Introduction: Computed tomography (CT) has numerous applications in clinical procedures but its main problem is its high radiation dose to the patients compared to other imaging modalities using x-ray. CT delivers approximately high doses to the nearby tissues due to the scattering effect, fan beam (beam divergence) and limited collimator efficiency. The radiation dose from multi-slice scanners is greater than the single-slice scanners and since multi-slice scanners increasingly employ a wide beam, 100 mm ion chambers currently used in measuring the CTDI100, are not capable of accurately measuring the total dose profile of the slice width. Therefore, the CT dose is underestimated by using them. The purpose of this study is to measure the Computed Tomography Dose Index (CTDI) of a GE multi-slice CT scanner (64-slice) using polymer gel dosimetry based on MRI imaging (MRPD). CTDI is the sum of point doses along the central axis and estimates the average patient dose during CT scanning.Materials and Methods: For measuring CTDI, after designing and fabricating the phantom and preparing the MAGIC gel, MRI imaging using a 1.5 T Siemens MRI scanner was performed with the imaging parameters of ST=2 mm, NEX=1, TE=20-640 ms and TR=2000 ms. CTDI was measured with a 100 mm ion chamber (CTDI100) and also the MAGIC gel with MRPD method for 10 mm and 40 mm CT scan nominal widths.Results: Following the measurement of the CTDI100 for 10 mm and 40 mm nominal slice widths of the multi-slice scanner using both ion chamber and MAGIC gel, the results showed that the ion chamber underestimates CTDI100 by 28.71% and 14.03% compared to gel for 10 mm and 40 mm respectively.Discussion and Conclusion: It was concluded from this study that gel dosimeters have the capability to measure CTDI in wide beams of multi-slice CT scanners whereas 100 mm standard ion chamber due to its limited length is not reliable even for a 10 mm beam width. In addition, due to the 3 dimensional nature of gel dosimetry, by using a MAGIC polymer gel, it is possible to obtain a lot of important information from the mentioned profiles such as the actual slice thickness and z-axis geometric efficiency. In addition to the stated parameters, the percentages of the total and partial homogeneities in the slice plane can be obtained only from gel dosimetry. The results of this study show that MAGIC polymer gel dosimetry based on MRI can be used as a supplementary method to using conventional ion chamber dosimetry especially in measurements for slice widths greater than 2 mm.

Introduction: The use of sophisticated radiographic techniques is absolutely necessary in dentistry.The use of these techniques exposes the sensitive organs of head and neck to x-rays. The aim of the present study was to investigate the absorbed dose of the thyroid gland in conventional spiral and spiral computed tomography techniques.Materials and Methods: In this experimental study, 10 TLD GR-200 circular dosimeters (Thermoluminans Detector) were used in male RANDO-like phantom (head and neck segment, i.e. the first 10 segments) in order to determine the radiation dose absorbed by the thyroid gland. Then spiral computed tomographies were provided from the anterior and posterior regions of the maxilla and mandible along with a lateral Scout view as a guide. Conventional spiral tomographies were prepared from the maxilla, mandible and both jaws with a panoramic radiograph as a guide. Data was analyzed using Kruskal-Wallis and Mann-Whitney tests using SPSS 11.5 (a=0.05).Results: The highest and lowest thyroid gland absorbed doses were observed with computed tomography of both jaws and conventional spiral tomography of the anterior maxilla, respectively (5.92±0.01 and 0.79±0.01 mSiv). The mean amount of the absorbed dose by the thyroid gland was lower in the conventional spiral tomography compared to computed tomography. The two techniques revealed significant differences in the absorbed doses except for conventional spiral tomography in the posterior and anterior regions of the mandible (p value=0.276).Conclusion: According to results of the present study, the absorbed dose of the thyroid gland in the conventional spiral tomography in different regions of the jaws was less than CT scan techniques. As a result, it appears the use of conventional spiral tomography is preferred over CT scans in limited regions where three-dimensional and cross-sectional views are required.

Background and Objective: Sinus extension is a physiological process that occurs in the growth cells of the paranasal sinuses and leads to increasing their volume over time, causing challenges in the dental implant process. This study was conducted to evaluate maxillary sinus morphometrics by cone-beam computed tomography (CBCT). Methods: This descriptive-analytical study was conducted on the CBCT images of 100 people (52 male and 48 female) with a mean age of 45. 32 ± 17. 41 and the age range of 27 to 63 years referring to an oral and maxillofacial specialized radiology clinic in Babol, Iran during 2019. The amount of maxillary sinus extension in the panoramic-like view was recorded based on the amount of its extension in terms of the first anterior tooth and the last posterior tooth. In the new net technologies (NNT) software, in the section related to creating panoramic-like views, first, in the axial sections, the starting point of the maxillary sinus was specified from the occlusal side, and the mediolateral dimensions were measured at distances of 3 mm above and 3 mm below. Results: The highest amount of maxillary sinus progress in the right anterior side was related to the mesial of tooth 5 (15%), and the highest amount of sinus progress in the left anterior side was related to the distal of tooth 3 (15%) and the mesial of tooth 4 (15%), which had no statistically significant differences. The most progress in the anterior area was related to the distal of the canine tooth and the mesial of the first premolar. The mean mediolateral sinus progress at 3 mm above the right nasal floor was higher in females than in males (P<0. 05). Gender and age had no statistically significant relationship with maxillary sinus progress. Conclusion: The maxillary sinus progress was almost equal in the left and right sides and also in males and females.

Thickening of extra ocular muscles are seen in a variety diseases and disorders. Normal values of these muscle's diameters are necessary for diagnosis and differentiation of pathologic conditions. Magnetic resonance imaging (MRI) and computed x-ray topography (CT) are essential studies for visualization of most normal and abnormal orbital structures.This study was performed for determining of the normative measurements of extra ocular muscles diameters and probable age and sex related differences in Iranian population.100 patients presenting for CT Scan of paranasl sinuses were evaluated and the diameters of their extra orbital muscle were measured and analyzed.Statistically, there was no significant difference between normal mean diameter of extra ocular muscles (right internal rectos, left external rectos, right superior complex group, left superior complex group, left superior oblique, right inferior oblique and left inferior oblique males and females results, but there were significant differences between age groups and right and left orbits about all measured parameters.Our study results can help ophthalmologists to accurately assess enlargement of the extra ocular muscles and the optic nerve.

Background: Paranasal sinus disease is one of the most common problems of patients that refer to ENT centers. Adding to clinical examination, imaging plays an important role in diagnosis and treatment. Also the imaging of paranasal sinuses is necessary before surgery. Although computed tomography is the modality of choice for these areas, it has some disadvantages which the most important one is its high patient's dose. The aim of this study is the comparison between cone beam volumetric tomography and conventional computed tomography computed tomography, in evaluation of these areas.Methods: In this descriptive-analytic study Coronal computed tomography imaged and cone beam volumetric tomography images were performed for40 patients referred to ENT department of Amir Aelam Hospital in Tehran, Iran. Computed tomography images were observed by general radiologist and cone beam volumetric tomography images by Maxillofacial radiologist and their results' were recorded. Also ENT surgeon recorded her observations during surgery. Data were analyzed using Mc Nemar test with Kappa and weighted Kappa agreement coefficient.Results: No statistical difference was shown between the efficacy of computed tomography and cone beam volumetric tomography in evaluation of paranasal sinuses (p>0.05).Conclusion: As there was not any difference between conventional computed tomography and cone beam volumetric tomography in the assessment of paranasal sinuses and additional advantages of the later, cone beam volumetric tomography is suggested for paranasal sinus imaging before surgery.

Introduction: Chronic sinusitis has been the most reported chronic and multifactorial disease in the last decades. The relationship between the anatomical diversity of the sinonasal complex and sinusitis is still under discussion. Computed tomography (CT) is the modality of choice for the evaluation of the sinuses and anatomic factors that predispose one to sinusitis. This study aimed to investigate the relationship between the anatomical variations of sinonasal complex and sinusitis of the maxillary sinuses using multi-slice CT scans. Materials and Methods: In this study, we evaluated CT scans from the paranasal sinuses of 106 patients (212 maxillary sinuses) referring to the Shahid Kamyab Hospital in Mashhad, Iran, that were prepared by 16-slice spiral CT machine (cutting thickness: 0. 75 mm). Normal anatomic variations which included agger nasi cells, ethmoid bulla, concha–, bullosa, paradoxical middle concha, and nasal septal deviation, were evaluated and recorded. The samples were divided into a healthy group, that showed no increase in mucosal thickness in the maxillary sinus walls, and a patient group (with sinusitis) that showed an increase of more than 2 mm in mucosal thickness of at least one wall. Chi-squared test and independent t-test were used to determine the association between the anatomic variations with maxillary sinusitis. Results: Chi-square test showed a statistically significant relationship between the presence of paradoxical middle concha and the deviation of the middle nasal septum with an increase in the thickness of the sinus mucosa (sinusitis) (P≤, 0. 001). Moreover, Student's t-test showed no statistically significant difference between the healthy and patient groups in the dimensions of concha bullosa, agger nasi cell, and ethmoid bulla. Conclusion: The findings of our study showed a relationship between paradoxical middle concha and deviation of the middle nasal septum with sinusitis of maxillary sinus. However, other sinonasal anatomical variations were not associated with the development of sinusitis.