Background: A VARIABLE RESOLUTION X-RAY ((VRX)) CT SCANNER provides a great increase in the spatial RESOLUTION. In (VRX) CT SCANNERs, the spatial RESOLUTION of the system and its field of view (FOV) can be changed according to the object size. One of the main factors that limit the spatial RESOLUTION of (VRX) CT SCANNER is the effect of the X-RAY focal spot. Materials and Methods: A theoretical study of the effect of X-RAY focal spot on the spatial RESOLUTION of (VRX) CT is presented in this paper. In this study, we used the parameters of an actual (VRX) CT SCANNER. By using the relevant equations, the effects of foal spot sizes of 0.6 and 0.1 mm were calculated on spatial RESOLUTION of the system at various opening half angles. Results: Focal spot size of 0.6 mm had no significant effect on spatial RESOLUTION of the system for opening half angles of above 14°. Even focal spot sizes of larger than 0.6 mm could not affect the spatial RESOLUTION of the system. For opening half angles of below 14°, foal spot size of 0.6 mm limited the spatial RESOLUTION of the system to 5.7 cycle/mm and caused great spatial RESOLUTION non-uniformity along the detector length. Conclusion: By focal spot size of 0.1 mm, the spatial RESOLUTION varied as a function of the opening half angle and increased to more than 30 cycle/mm. Additionally, focal spot size of 0.1 mm minimized the spatial RESOLUTION non-uniformity along the detector length.

Introduction: VARIABLE RESOLUTION X-RAY ((VRX)) CT is a new type of CT that can image objects at various spatial RESOLUTIONs. In a (VRX) CT SCANNER, the spatial RESOLUTION increases at the cost of reduction in the field of view (FOV). An important factor that limits the spatial RESOLUTION of the (VRX) CT is the effect of focal spot size. Also, the optimum magnification is different at each incident angle.Material and Methods: To investigate the spatial RESOLUTION and the FOV in (VRX) CT, we used the numerical parameters of an actual (VRX) CT SCANNER. The effects of decreasing the focal spot size and optimizing magnification on the spatial RESOLUTION and the FOV of the system were studied theoretically.Results: The focal spot size was found to greatly limit the spatial RESOLUTION of the (VRX) CT at the small incident angles. By decreasing the focal spot size, the spatial RESOLUTION was comparatively improved. Optimization of the system magnification without decreasing the focal spot size could greatly increase the spatial RESOLUTION of the system. After optimization of magnification, the FOV of the system decreased significantly.Discussion and Conclusion: The spatial RESOLUTION of the system after optimizing the magnification increased from 7.5 to more than 35 cycles/mm and also the effect of the focal spot no longer limited the spatial RESOLUTION at incident angles smaller than 13o. The disadvantage of optimization of magnification was a great decrease in the FOV of the system. The optimization of magnification has the reverse effect on the spatial RESOLUTION and the FOV of the system so at each incident angle, according to the importance of spatial RESOLUTION or FOV, the system magnification can be set to lead to the desirable condition.

Structural health monitoring is becoming more reliable as technology advances. Many structures are in use throughout cities and environments that require constant attention due to fatigue of corrosion and environmental effects such as floods, earthquakes, or strong winds. This means that with the advent of new damage detection techniques, authorities can make sure that these vital structural elements, such as road signs or traffic lights and so on, are safe. The important key to these techniques is that they must be simple and relatively inexpensive. Therefore, an attempt was made to use techniques in medical practice and adapt those to structural members. In this article, the effectiveness of X-RAY computed tomography in the inspection of urban structures and building structures is discussed. X-RAY tomography is a non-destructive method based on X-RAY absorption, widely used in the medical field. By using this method, it is possible to study and examine the internal structure of old structures to fix defects and maintain the safety of residents, as well as to maintain them as best as possible. For example, urban structures such as electric poles and traffic signs cause financial losses or even deaths due to natural hazards or wear and tear every year. One of the features of this method is its high accuracy and speed in checking the member. Considering the capabilities of this method, in this research, a baggage inspection device at the MehrAbad airport was used to examine a number of concrete and wooden samples to identify defects such as cracks, holes, or knots in wooden samples. The investigation results are directly related to the device's power and the duration of radiation used on the sample. According to the results, defects such as cracks in concrete or knots in wood can be observed.

Background and Objectives: Knee joint as the largest synovial joint in the body, consists of the lateral collateral ligament, cruciate ligament, and medial and lateral meniscus. For proper management, identification of damage to any structures of the knee is necessary. In this study, snsitivity, specificity, and diagnostic accuracy of high RESOLUTION CT scan in meniscal lesions, were assessed. Methods: In this test accuracy assessment study, 57 patients with a history of positive meniscus lesion, who referred to Ayatollah Mousavi Hospital of Zanjan city from 2015 to 2016, were investigated by magnetic resonance imaging, high RESOLUTION computed tomography, and arthroscopy. Magnetic resonance imaging and high RESOLUTION computed tomography data, were compared to knee arthroscopy as the diagnosis gold standard. Kappa (κ ) correlation coefficient was used to calculate the consistency of the tests. Results: Out of the 57 patients presented with meniscal lesion, 52 patients (91. 2%) were male and 5 patients (8. 8%) were female. The highest incidence of meniscal lesions was in ages from 21 to 30 years. Among the causes of meniscal lesions, exercise with prevalence of 47. 9%, was the most prevalent cause of injury. In comparison with arthroscopy, the sensitivity, specificity, and accuracy of high RESOLUTION computed tomography were determined to be 64. 7%, 55%, and 60%, respectively, and for magnetic resonance imaging were 85. 2%, 50%, and 77. 5%, respectively. Conclusion: According to the results of the present study, specificity, sensitivity, and accuracy of high RESOLUTION computed tomography in the diagnosis of meniscal lesions, was lower than the previous studies.

Background: Evaluation of performance is essential prior to human studies. The objective was to evaluate the physical performance of the new integrated PET/CT system according to NEMA and IAEA standards.Materials and Methods: A series of Quality control procedures was performed on GE DiscoveryTM STE16 Whole Body PET‐CT system.Results: (1).2 cold and 4 hot spheres were visible in 3D mode with contrast values of 28.5%, 35.7%, 50.8%, 69.2% from smallest to largest hot sphere for cold spheres from 53.4% and 61.6%. In 2D mode 2 cold and 3 hot spheres were visible.(2). The average transverse and axial spatial RESOLUTION (FWHM) at 1 cm off center was 5.03 (5.05) mm and 10 cm off axis was 5.2 (6.1) mm in 2D, and 5.4 (6.9) mm and 6.1 (6.6) mm in 3D.(3). The average sensitivity for two radial positions (r=0 cm and r=10 cm) was 1.7 cps/kBq in 2D and 8.4 cps/kBq in 3D.CT: (1). All slice thicknesses (5, 3.75, 2.5, 1.25) mm are acceptable except 0.625 mm.(2). Standard deviation in the image noise uniformity, for center and 2 radial positions, was 3.27, 3.2 and 3.21 respectively.Conclusion: The system has excellent overall performance in 2D and 3D modes in particular high sensitivity. Hence, CT alone is good enough for diagnostic use.