Background & Aims: Nowadays, imaging of the blood supply of the heart muscle by single photon emission computed tomography (SPECT: Single Photon Emission Computed Tomography) due to its non-invasive nature and providing information with physiological value and low cost compared to the valuable angiography method. It is highly diagnostic. But these images undergo changes and artifacts under the influence of factors, the result of which is the reduction of the diagnostic accuracy of the images and false positive cases. During the detection process, several physical effects such as attenuation, scattering, and collimator response function affect the frequency of emitted photons,this leads to the destruction of the contrast and as a result of reducing the quantitative and qualitative accuracy of the images. Attenuation, as the most destructive factor of SPECT images, reduces the quality of SPECT images of heart blood supply and reduces the sensitivity of tests related to the diagnosis of coronary artery diseases, and for non-uniform environments, especially in nuclear imaging of chest areas. And the heart is necessary to produce a map of patient attenuation coefficients. The existence of scattered photons is also one of the main factors of error in quantization,the detection of scattered events affects the contrast of the lesions and causes the lack of image resolution and signal-to-noise ratio. Therefore, to correct the attenuation and scattering of the rays in the heart images quantitatively and qualitatively, patterns are needed in SPECT systems. Due to the importance of the topic, various research groups around the world have presented their research and results on correcting the effect of scattering of rays and also correcting the effect of weakening the rays. If there was no limitation of energy resolution, it was easily possible to identify the scattered rays and prevent them from being recorded in the image. Because we know that scattered rays lose energy. Because gamma rays are single energy and their energy amount is completely known. Therefore, each photon with less energy will represent scattered rays, but due to the limited energy resolution of the gamma camera, a range is usually considered on the sides of the main energy, which is called the energy window. It is assumed that the photons recorded in this energy range are primary photons, but in fact, many photons scattered in the body are also recorded in this window. These scattered rays do not carry correct spatial information and lead to a decrease in image resolution and contrast and quantization errors in the image. In nuclear medicine, instead of researching and examining the patient or processing the image of the patient, simulated images can be examined. Simulators can provide information about each of the image destruction factors. The purpose of this research is to propose a new method for scattering correction, in this research, a combination of Monte Carlo and modeling is used for the rapid production of scattered views, and in the proposed method, the two-matrix method is used, this method At the stage of generating mathematical views, dispersion is added and this problem leads to the removal of scattered rays. As a result, an image is reconstructed that is free from the effects of attenuation and non-ideal dispersion and leads to an increase in contrast and improvement of power. Detecting waste, increasing the signal-to-noise ratio, and increasing the accuracy of quantification. Methods: In this study, the effect of applying attenuation and dispersion correction using two energy windows (DEW) and three energy windows (TEW) methods in cardiac aspect imaging was investiGATEd and evaluated, and to simulate cardiac aspect imaging, a special code similar to SAR Monte Carlo GATE was used as the SPECT imaging system and XCAT digital phantom with activity distribution and realistic attenuation map was used to model the human trunk. Results: Comparison of image contrast improvement in different modes of attenuation and dispersion correction shows that the highest image contrast is obtained from the (TEW1+AC) method with an average increase of 25% and MSE in different modes of attenuation correction. And the dispersion compared to the reference image was reduced from 51. 5% to 54. 5%. Compared to the reference image, MSE decreased from 1. 4 in Un_Cor to 1. 15, 1. 13, 1. 12, and 1. 14 in AC+TEW1, AC+DEW, AC, and AC+TEW2, respectively, and the signal-to-noise ratio (SNR) increased up to 71% in all methods of applying dispersion correction along with attenuation correction compared to applying attenuation correction (AC). Conclusion: In this study, the effect of attenuation and dispersion correction in 5 non-correction modes, with attenuation correction, attenuation, and dispersion correction using two-window and three-window methods with triangular approximation and three-window with trapezoidal approximation on We evaluated XCAT phantom simulated images and heart muscle perfusion images by SPECT method and 4 different parameters were used to compare and evaluate the images, including profile, contrast, mean squared error (MSE) and signal to noise. According to the results of the quantification of reconstructed images, it is possible to apply dispersion correction along with attenuation correction.

Proton beam therapy (PBT) is a modern radiotherapy technique characterized by superior target coverage compared to conventional modalities. In this work, a comprehensive GATE Monte Carlo model was developed and then validated for a double scattering proton treatment nozzle. To this aim, a double scattering treatment nozzle was modeled in the GATE toolkit. Proton beam flatness and its symmetry, secondary neutron effective dose, and dosimetric performance were characterized. A proton beam flatness of 98. 6% was observed downstream of the aperture for a 7×7 cm2 field size. The beam flatness deteriorates at the edge of the treatment field for the single scattering model while it remains approximately constant for the double scattering one. Compared to the single scattering delivery, the second scattering model results in a 1. 3 times increase in neutron dose for the nickel as the optimal collimator/aperture material. Furthermore, a flat beam modulation width of 3. 50 cm is formed with a distal edge at 7. 86 cm in water using the GATE and MCNPX codes. The GATE model agreed with the MCNPX results. The results show that the constructed GATE model results in a fast and accurate simulation of passive scattering PBT.

The spot-scan based methods are expected to perform better than other methods for proton therapy in delivering the dose to the intended target. In this study, the GATE computer code is used to evaluate important dosimetric quantities in proton therapy, such as Full width at half maximum, peak position, range and peak-to-entrance dose ratio (percentage depth dose) in the proton therapy process under the same conditions based on spot scanning and passive scattering. Water phantom was selected and system energy parameters were measured using a set of depth-dose curve in the energy range of 120 to 235 MeV. Bragg peaks were generated with an accuracy of 0. 7 mm in range. Spread out Bragg-peak were produced with 7 cm modulation and 10 mm range accuracy and peak-to-entrance dose ratio difference at an input dose of 8%. To evaluate the versatility of the beam, the Full width at half-maximum was evaluated with a maximum difference of 7% between the two methods. As a result, based on the simulations performed for different beam delivery systems, the ability of the spot scanning method in adapting to the target volume, better control over dose distribution and less extra-tumor dose was demonstrated.

GATE Induced Drain Leakage (GIDL) current is one of the main leakage current components in Silicon on Insulator (SOI) MOSFET structure and plays an important role in the data retention time of DRAM cells. GIDL can dominate the drain leakage current at zero bias and will limit the scalability of the structure for low power applications. In this paper we propose a novel technique for reducing GIDL and hence off-state current in the nanoscale single GATE SOI MOSFET structure. The proposed structure employs asymmetric GATE oxide thickness, which can reduce GIDL current, and hence Ioff current to about 98% in comparison with the symmetric GATE oxide thickness structure, without sacrificing the driving current and losing GATE control over the channel. This technique is very simple in the fabrication point of view in CMOS technology.

Today more than ever, we need high-speed circuits with low occupancy and low power as an alternative to CMOS circuits. Therefore, we proposed a new path to build nanoscale circuits such as Quantum-dot Cellular Automata (QCA). This technology is always prone to failure due to its very small size. Therefore, designers always try to design fault-tolerant GATEs and provide methods to increase the reliability of QCA. By adding redundant cells, the possibility of some defects such as cell omission and cell addition is somewhat reduced. However, in the face of defects such as stuck-at 0/1 faults, Clock fault and bridging fault. We can greatly increase the fault tolerance by appropriate placement and using fault tolerant GATEs with a suitable structure. In this paper, we design the XOR/XNOR GATE with the approach of preventing stuck-at 0/1 fault, clock fault, and bridging fault using the first NNI GATE tolerating cell addition fault.

Problems related to sedimentation and depositions can be minimized by using a system where weirs and GATE are combined in open canals while the floated materials run over and sediments run under the structure. Because of effect of overflow on underflow, the variation rate of discharge coefficient with geometric and hydraulic parameters is different with their use each other separately. It is important for cylindrical weir-GATE because the flow nape will sit on the weir completely the current work describes the results of experimental investigation on effect of weir flow on GATE discharge coefficient for cylindrical weir-GATE. In this way the GATE discharge is measured against upstream water depth in two condition of weir flow and without weir flow. The experiments are carried out in a laboratory flume 10 m length, 60 cm wide and 70 cm height. Results indicate that increasing dimensionless parameters of Hw/a and Hw/D cause decreasing the discharge coefficient for weir flow and it rises about 1-25% without weir flow. For a constant values of the Hw/a increasing the GATE height, the effect of weir on GATE discharge coefficient decreases for the cylindrical weir-GATE.

Electromagnetic radiation reflected from ground features is scattered by atmospheric particles and molecules in its way to satellite sensors. This causes some degree of haze in satellite imagery produced. scattering and its consequent produced haze in imageries vary with time and weather condition. Consequently, image analysis becomes difficult. It is sometimes necessary to omit or at least reduce atmospheric effects on images in hand. This article studies application of an atmospheric correction model on Landsat TM image of an area in north mountainous part of Iran. The result of atmospheric correction was evaluated via comparing the product of maximum likelihood classification on corrected and on non corrected images. The results show that applying this method considerably reduces the haze effect on corrected image and produces higher classification accuracy.