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.

Cardiovascular disease remains the principal cause of death in the modernized world. Several novel noninvasive imaging techniques have been recently developed to improve diagnosis of cardiac and coronary disease. Of these advances, Multidetector Computed tomographic (MDCT) angiography has evolved most dramatically to transform Computed Tomography from a single-slice trans-axial modality to a three-dimensional volumetric technique. Current generation 64-detector row CT scanners allow for large volume coverage with submillimeter spatial and sub-second temporal resolution. These advances enable important new applications for MDCT in the assessment of cardiac and coronary anatomy. In this report, we discuss in depth potential appropriate uses of cardiac and coronary MDCT angiography.

Background: Paratracheal air cysts (PACs) are extraluminal collections of air mostly located adjacent to the right of the trachea at the level of the thoracic inlet. Although, PACs are usually asymptomatic, the lesions do occasionally cause complications such as chronic cough, difficult intubation, and right-sided recurrent laryngeal nerve palsy. The purpose of the present study was to demonstrate the appearance and prevalence of PACs through retrospective review of multi detector Computed Tomography (MDCT) of the chest.Methods: In a cross sectional study, a total of 1054 chest MDCT scans of patients that referred to MDCT unit of Alzahra hospital in Isfahan from 2012 to 2013 were reviewed. Exclusion criteria were history of thoracic surgery, history of tracheostomy or tracheal intubation and presence of tracheal lesions. PACs were evaluated for size and the presence of visible communication with the trachea. Patient demographics, age and sex were also collected.Findings: Of the 1054 patients evaluated, 112 (10.6%) of them had PACs.103 (92%) patients had one PAC, and 9 (8%) had two PACs. Age of the patients ranged from 6 to 91 years. In 43 (38.4%) of the patients, a direct communication with the trachea was seen. Sizes of the PACs ranged from 1 mm to 13.1 mm with mean±SD of 3.89±2.72 mm. PACs were<5 mm, 5-10 mm, and>10 mm, in 86 (76%), 21 (20%), and 5 (4%) of the patients, respectively. PACs which had communication with trachea, were significantly larger than the cysts without communication (P=0.01).Conclusion: PAC is a common finding on CT examinations of the chest that occur in an expectable location.The exact pathogenesis of PAC is unclear but presence of these cysts in a wide age range may suggest congenital and acquired causes.

Background: In kidney transplantation decision about the proper kidney donation is different between surgeons, but simple vasculature anatomy and a kidney without abnormalities are the most important reasons of choosing a kidney. Therefore complete assessment of renal vessels of a live donor with noninvasive techniques is a necessity for nephrectomy. For delineation of the kidney vasculature anomalies and urinary system abnormalities, Multi-Detector CT seems to be excellent method for evaluation.Methods: In this study 59 live donors were assessed with Multi-Detector CT Angiography. After injection of contrast media, we acquired images with 0.6 mm slice thickness. Processing and three dimentional reconstructions were done and the accessory arteries, early branching of main renal artery, the number of main renal vessels and the ureters were assessed.Findings were compared with the nephrectomy results.Results: In Multi-Detector CT Angiography the prevalence of accessory renal artery was 3/4% with 98% accuracy, early branching of main renal artery was 8/4% with 100% accuracy. Multiplicity of renal veins was seen in 8/4% of donors with 98% accuracy. Duplicated ureter was not seen in any of the donors.Conclusions: The accuracy of CT Angiography is 95% for depicting accessory renal artery and multiple renal artery and 100% for early branching.These results were comparable with findings in conventional angiography.Studies showed this method more valuable than M.R. Angiography and digital subtraction angiography. It is less invasive and can be named as the gold standard method in the diagnosis of anomalies of vessels & collecting system in live donors.

Background: Cone beam Computed Tomography (CBCT) and Multidetector Computed Tomography (MDCT) are frequently used in dental and maxillofacial problems. This study aimed to assess the genotoxicity and cytotoxicity effects of CBCT and MDCT radiographies on exfoliated buccal epithelial cells during dental examinations. Methods: This prospective experimental study was conducted at Babol University of Medical Sciences (Babol, Iran) from March 2021 to April 2021. Buccal mucosa smears were collected bilaterally pre-exposure and 12 days after CBCT or MDCT examinations. To compare the frequency of micronuclei and other cytotoxic cellular changes such as pyknosis, karyolysis, and karyorrhexis, the paired sample t test and Wilcoxon test were used. In addition, independent sample t test, Mann-Whitney, and Chi square tests were used to investigate the differences between the imaging methods and between men and women. All statistical analyses were performed using the SPSS software, and P≤0.05 was considered statistically significant. Results: The current study included 60 adult patients (30 patients in each group), ranging in age from 21 to 50 years. The micronuclei and the other cytotoxic cellular changes increased significantly after CBCT and MDCT radiographic examinations on the 12th day compared to the pre-exposure results (P<0.001). MDCT had statistically higher cytotoxic and genotoxic effects than CBCT (9.4%, 23.1%, and 40% higher values in micronucleus frequency, the mean frequency of micronuclei, and other cytotoxic changes, respectively). There were no significant differences between men and women in the two examination methods (P=0.46 and P=0.49, respectively). Conclusion: Dental examinations with CBCT and MDCT can increase cytotoxicity and chromosomal damage in both men and women. Due to its lower radiation toxicities, CBCT can be recommended as an alternative to MDCT for dental examinations.

Background: CT techniques and procedures have been expanded in the past decades, leading to an increase in the use of CT. At the same time, the radiation dose to the patient and the concern surrounding this issue has also increased. Objectives: The goal of this study was to assess clinical image quality and x-ray dose from various Computed Tomography (CT) scanners in order to identify the CT scanners that produce the least radiation dose to patients with exact acceptable image quality for diagnosis. Patients and Methods: Non-randomized clinical image data were collected from six hospitals on 16, 32 and 64 slice CT scanners. A total of 900 patients who underwent chest, abdomen, and brain scans were used for image quality evaluation and dose assessment. The image qualities were evaluated by five observers on 1-5 visual grading scale. The CT dose volume index (CTDIv) and dose length product (DLP) was documented from the image display. Results: The averaged CTDIv was 64. 96, 70. 2, and 75 mGy for the brain, 11. 65, 15. 53 and 17. 11 mGy for the chest, and 13. 41, 18. 44, and 19. 42 mGy for the abdomen from 16, 32 and 64 slice scanners respectively. The averaged image quality scores were 3. 68, 3. 82, and 4. 81 for the abdomen, 3. 01, 4. 27, and 4. 42 for the chest, and 4. 92, 4. 94, and 4. 99 for the brain from 16, 32 and 64 slice scanners respectively. Conclusion: Sixteen slice CT scanner delivered the minimum radiation dose to patients in contrast with the 32 and 64 slice CT scanners, and the image quality was adequate for diagnosis. Both 32 and 64 slice CT scanners produced more than acceptable image quality as well as more than needed dose to patients. The patient dose from the 32 and 64 slice scannersmaybe reduced by dropping their image quality to close to the 16 slice CT scanner.

Intestinal lipomatosis also known as lipohyperplasia is a rare disease. Diffuse infiltration of the fatty tissue mainly in the submucosal layer is characteristic. It is usually asymptomatic and found incidentally. We report a case of lipomatosis in the terminal ileum and ileocecal valve. Multidetector Computed Tomography (MDCT) with contrast enhancement showed fatty infiltration of the terminal ileum and ileocecal valve.

Background: Abdominal CT using a tube-current modulation technique may result in artifacts due to changes in the position of the patient’ s arms, resulting in poor image quality and excessive radiation exposure. To solve these problems, the patient’ s arm is positioned mainly on the head or outside the examination area. Objectives: An optimization method to acquire high-quality images in CT examination by comparing the radiation dose and image according to the change in arm position and the use of the tube-current modulation method in CT examination. Materials and Methods: To analyze the CT images, the mean, standard deviation (SD), and coeffi cient of variation (COV) of the Hounsfi eld unit (HU) of the CT were obtained by measuring the pixel values of the heart, chest, lung, and bone using region of interest (ROI) manage. The dose of Computed Tomography dose index (CTDI) and dose length product (DLP) according to the position of the arm. Results: The arms up position of CTDIvol and DLP values were lower than the arms down position. In the z-axis thickness modulation (Z-DOM), the tube current increased in the shoulders, decreased in the lungs, and increased in the abdomen. There was no artifact when the arms were raised, but an artifact was present when the arm was lowered. The calculated peak signal-to-noise ratio (PSNR) for the Z-DOM application in the CT scan of the anthropomorphic phantom by applying automatic exposure control (AEC) was 38. 21 dB. There was no signifi cant diff erence between SD and COV using Z-DOM and the fi xed tube current technique (P > 0. 05). Noise in the image increased when the arm was raised, and dose increased in the thyroid and upper chest. Conclusion: The position of the upper arms directly aff ects the image in the MDCT imaging of the anthropomorphic phantom. Therefore, it is possible to increase the quality of the image by reducing the amount of artifacts and the amount of radiation by orienting the arms upward. This optimal test method could be used in clinical practice to achieve high image quality and low noise in the MDCT of trauma patients.

We present two cases of hyperthyroid cardiomyopathy (CMP) caused by Graves’ disease in which Multidetector Computed Tomography (MDCT) findings provided specific diagnostic clues, guiding the attending physician to a prompt diagnosis and allowing rapid initiation of therapy. We believe that a combination of diffuse thyroid enlargement, with decreased attenuation on non-enhanced chest CT, thymic hyperplasia and cardiomegaly (i. e. predominantly right heart failure with enlargement of the left atrium) are suspicious CT findings of hyperthyroid CMP.