نتایج جستجو برای: energy resolution
تعداد نتایج: 928621 فیلتر نتایج به سال:
Introduction: Image quality and accuracy of in vivo activity quantification in SPECT are affected by collimator penetration and scatter components, especially in high energy imaging. These phenomena highly depend on the collimator characteristic and photon energy. The presence of penetrated and scattered photons from collimator in SPECT images degrades spatial resolution, contr...
seismic attribute is a quantitative measure of an interested seismic characteristic. there are several seismic attributes. in recent years, time-frequency (tf) attributes have been developed which to reach them, tf analyzing of seismic data is required. a high resolution tf representation (tfr) can yield more accurate tf attributes. there are several tfr methods including short-time fourier tra...
Introduction: Most beta and gamma radiation radioisotopes used for treatment are not suitable for imaging. The bremsstrahlung images on a conventional gamma camera helped to localize the radionuclide within and outside of the lesion. Secondary scattering of gamma rays of higher energy and bremsstrahlung causes contamination in the energy window and reducing the contrast and resolution of the im...
Background and purpose: Imaging which is used in nuclear medicine is done using emit gamma rays whereas therapy in nuclear medicine is performed by applying radionuclide’s which emit beta radiation. Using Bremsstrahlung is a new field which is recently introduced in imaging. In the Bremsstrahlung imaging, collimator design should not be based on energy peak and whole energy spectrum should be c...
Background: The nuclear medicine systems are very sensitive to the variation of the magnetic field. Photomultiplier tubes amplify low energy light signal and change it into electrical current. Low magnetic field can produce some variations in uniformity and special resolution of SPECT systems. In this study, we tried to evaluate the effects of magnetic field on the function of nuclear medic...
Objective(s): The energy resolution of a cadmium-zinc-telluride (CZT) solid-state semiconductor detector is about 5%, and is superior to the resolution of the conventional Anger type detector which is 10%. Also, the window width of the high-energy part and of the low-energy part of a photo peak window can be changed separately. In this study, we used a semiconductor detector and examined the ef...
a one dimensional dynamic model for a riser reactor in a fluidized bed catalytic cracking unit (fccu) for gasoil feed has been developed in two distinct conditions, one for industrial fccu and another for fccu using various frequencies of microwave energy spaced at the height of the riser reactor (fccu-mw). in addition, in order to increase the accuracy of component and bulk diffusion, instanta...
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