Spectroscopy and Optimizing Semiconductor Detector Data Under X and γ Photons Using Image Processing Technique

Quantitative assessment of full-width at half-maximum and detector energy threshold in X-ray imaging systems

BACKGROUND

The response function of imaging systems is regularly considered to improve the qualified maps in various fields. More the accuracy of this function, the higher the quality of the images.

METHODS

In this study, a distinct analytical relationship between full-width at half-maximum (FWHM) value and detector energy thresholds at distinct tube peak voltage of 100 kV has been addressed in X-ray imaging. The outcomes indicate that the behavior of the function is exponential. The relevant cut-off frequency and summation of point spread function S(PSF) were assessed at large and detailed energy ranges.

RESULTS

A compromise must be made between cut-off frequency and FWHM to determine the optimal model. By detailed energy range, the minimum and maximum of S(PSF) values were revealed at 20 keV and 48 keV, respectively, by 2979 and 3073. Although the maximum value of FWHM occurred at the energy of 48 keV by 224 mm, its minimum value was revealed at 62 keV by 217 mm. Generally, FWHM value converged to 220 mm and S(PSF) to 3026 with small fluctuations. Consequently, there is no need to increase the voltage of the X-ray tube after the energy threshold of 20 keV.

CONCLUSION

The proposed FWHM function may be used in designing the setup of the imaging parameters in order to reduce the absorbed dose and obtain the final accurate maps using the related mathematical suggestions.

Appraisal of new density coefficient on integrated-nanoparticles concrete in nuclear protection

The most important material for shielding is concrete in nuclear facilities which performance can be improved by addition some Nanoparticles (NP) at the various concentrations. Nanoparticles, which have a distinctive potential for bio-radiation and shielding of nuclear reactors, are used in many areas due to their special characteristics, which lead to an improvement in the mechanical properties and the pore structure of the concrete shield. The aim of this research was to initiate a novel coefficient (n), experiment to theory density ratio for integrated NP at different nanoparticle concentrations (xnano), established upon purely mathematical viewpoints and some appropriate physical objectives.

Evaluation of gamma and electron radiations impact on vitamins for onion preservation

Food irradiation is a process in which food and other consumer products are exposed to gamma rays, X-rays or electron beams after extraction. This method is particularly important in order to reduce infectious agents and to extend the shelf life of the product. The target radiation is done with different devices, so self-sufficient radiation and panoramic radiation -including product and source overlap, planar and categorical radiation- is the major characteristics. Besides, a high performance liquid chromatography device (10% methanol, 70%-80% distilled water and 10% ethanol) is utilized to measure the chemical substance of pyridoxine (vitamin B3), thiamine (vitamin B6) and vitamin C of Vidalia or sweet onions. In our research, gamma-cell 220 and Rhodorton electron facilities were utilized to irradiate the onion crop. This project focuses on increasing the shelf life of agricultural products, especially onions, using energy of 1.25 MeV for both gamma irradiation and electron beam, and measuring the amount of vitamins B3, B6 and C, which are the nutrients of this product. The prepared onion samples were exposed under electron and gamma irradiations by two doses of 200 and 500 Gy at 25 °C. Then, a liquid chromatography device was utilized to measure the vitamins. The results showed that the onions were not damaged by 200 Gy doses and their nutritional properties were preserved, which means that not only can vitamins with this dose be retained without any spoilage for 30 days, but also eliminate pathogenic microorganisms. The process indicated that using 200 Gy radiations does not endanger the health of food and consumers.

Introducing a novel coefficient on mixed-nanoparticles material: relationship between the theoretical and experimental densities

Nanoparticles (NPs) indicating a unique potential in bioradiation and nuclear reactor shielding are employed in many fields due to their particular specifications leading improving the mechanical properties as well as pore structure of the concrete-shield. The aim was to introduce a novel coefficient ( ξ ), namely the experimental to theoretical density ratio for mixed-NPs material at various nanoparticles percent concentrations (ω n a n o ) based on pure mathematical aspects along with the some suitable physical purposes by Monte Carlo method. The change in the mixture density to the change inω n a n o is always proportional to theω n a n o value. The density will become maximum at theω n a n o ∗ in which the physical, morphological and chemical features of NPs along with the amounts of voids in the material have a key role over estimating porosity percentage. The NPs' separation probability as born-cascaded-pairs towards very small radii may be formulated as ξ - ξ - 1 + ω n a n o ∗ + k ' ' | ω n a n o - ω n a n o ∗ | = k ' wherek ' andk ' ' are constant values. In conclusion, the theoretical results may be experimentally used in future work for different applications such as designing shield at a nuclear facility.

Determination of Gamma Camera's Calibration Factors for Quantitation of Diagnostic Radionuclides in Simultaneous Scattering and Attenuation Correction

OBJECTIVE

The characterization of cancerous tissue and bone metastasis can be distinguished by accurate assessment of accumulated uptake and activity from different radioisotopes. The various parameters and phenomena such as calibration factor, Compton scattering, attenuation and penetration intrinsicallyinfluence calibration equation, and the qualification of images as well.

METHODS

The camera calibration factor (CF) translates reconstructed count map into absolute activity map, which is determined by both planar and tomographic scans using different phantom geometries. In this study, the CF for radionuclides of Tc-99m and Sm-153 in soft tissue and bone was simulated by the Monte Carlo method, and experimental results were obtained in equivalent tissue and bone phantoms. It may be employed for the simultaneous correction of the scattering and attenuation rays interacted with the camera, leading to corrected counts. Also, the target depth (d) may be estimated by a combination of scattering and photoelectric functions, which we have published before.

RESULTS

The calibrated equations for soft tissue phantom for the radionuclides were obtained by RTc = - 10d+ 300 and RSm = -8d + 100, and the relative errors between the simulated and experimental results were 4.5% and 3.1%, respectively. The equations for bone phantom were RTc = -30d + 300 and RSm = - 10d + 100, and the relative errors were 5.4% and 5.6%. The R and d are in terms of cpm/mCi and cm. Besides, the collimators' impact was evaluated on the camera response, and the relevant equations were obtained by the Monte Carlo method. The calibrated equations as a function of various radiation angles on the center of camera's cells without using collimator indicated that both sources have the same quadratic coefficient by -2E-08 and same vertical width from the origin by 8E-05.

CONCLUSION

The presented procedure may help determine the absorbed dose in the target and likewise optimize treatment planning.