حجت الله ماهانی

Modeling and simulation are crucial in designing and developing complex systems, such as cargo scanner systems. A cargo scanner is a device used to scan and inspect cargo transported by air, land, and sea. These scanners are usually used by customs and security centers to identify potential threats such as weapons, explosives, and contraband. One of the key benefits of using modeling and simulation is that it allows designers to test different scenarios and configurations without the need for physical prototypes. This can save time and money, as well as reduce the risk of costly mistakes. This study examines how the parameter angle affects detector responses in truck cargo scanner systems using the MCNPX code. The angle refers to the angle at which the beam generated from the beam generator interacts with the detector's normal surface, an important factor in ensuring the accuracy and reliability of cargo scanning systems in imaging. Initially, the X-ray spectrum output was calculated from the accelerated 6 MV electrons due to tungsten target impact and validated against spectra from other studies. The results demonstrated good agreement between the output spectra. The changes in counts recorded in the vertical direction of the detector arrays showed that the count difference between the lowest pixel and highest pixel is approximately 33%, while the count changes from the closest pixel to the farthest pixel to the beam generator in the horizontal direction are about 60%. Subsequently, the angle of each array was adjusted so that the emitted rays from the cone beam generator were perpendicular, and this case was compared to cases where the array angle was 20 and 30 degrees. The results revealed that when exposed to perpendicular radiation, the signal recorded in detectors is greater than that of a rotated detector, and the count rate in the detector decreases as the angle increases.

Exploration of radioactive materials has been mainly performed by either airborne- or ground-based monitoring at the earlier steps. As the airborne monitoring using a helicopter (or airplanes) suffers from low spatial resolution, a radiation worker then surveys potential anomalies with a hand-held monitor to extract the radiological map. Due to possible rough terrain, ground-based monitoring faces some difficulties and is expensive or time-consuming. Drones fill a gap between airborne- and ground-based monitoring in the exploration of nuclear materials and facilities and complement the exploration process. Furthermore, the utilization of drones leads to a reduction in the time spent by a radiation worker in a radiological environment. In this study, a radiation detector-equipped unmanned aerial vehicle (UAV) has been utilized to explore nuclear materials. The UAV consisted of a hexacopter, a scintillation detector, a photomultiplier tube, a positioning system, a mini-computer, and a data-link system for radiation data. The results show the effect of the height of flight on the exploration is more considerable than the speed and thus low altitudes are preferred. It can be concluded that the developed radiological-monitored UAV can be utilized for the exploration of natural radioactive materials.

Cancer is a significant public health problem worldwide and one of the leading causes of death worldwide. Breast cancer and fibroids are common among women, and if they are diagnosed on time, recovery and treatment will increase significantly.
In this article, breast cysts are diagnosed based on the surface temperature characteristic of breast tissue. For this purpose, the temperature characteristics of a breast with a cyst have been evaluated. Heat transfer inside the breast is modeled by Penne’s bio-heat equation and solved by the finite element method. In this study, due to the difference in the dielectric properties of healthy and tumor breast tissue, the temperature distribution on the surface of the breast with a cyst of different sizes was determined. For this purpose, parameters such as temperature and SAR levels were examined and evaluated. The results show that with a similar amount of total energy for electromagnetic waves, the temperature level of the tissue exposed to the waves remains constant regardless of the input power combination. Also, results show that as the size of the tumor increases, the effect of radiation on breast tissue increases, and therefore the malignant area can be distinguished from the healthy area of breast tissue. The results show the difference in the surface temperature characteristics of the normal breast and breast with a cyst of various sizes, which can be a criterion in diagnosing the complication of breast cysts compared to normal breasts.

This radiological monitoring system consisting of a 2-inch NaI(Tl) crystal coupled to a PM tube and mounted on a multi-rotor UAV has been developed to fast detect radioactive sources. To assess its performance, a set of experiments for the detection of low-level Co-60 and Cs-137 point sources in a soccer field was performed. Then, the radiological map was made and then fused with the geographical one using image processing techniques. The results show that at 50 cm, all 5-point sources were successfully identified in their actual locations. By decreasing the flight height, the ability of the drone-based radiological monitor in recognizing radioactive sources significantly increases. The results confirmed that the drone system with the scintillation detector enabled the accurately identifying radiological anomalies by surveying a contaminated area.