To improve spatial resolution, positron emission tomography (PET) systems are being developed with finer detector elements. Unfortunately, using a smaller crystal size increases intercrystal Compton scatter and X-ray escape crosstalk, causing positioning errors that can lead to degradation of image contrast. We investigated the use of extremely thin ( 300 m) lead strips for passive shielding of...

Introduction:  In  this  study,  we  utilized  the  MCNP4C  Monte  Carlo  code  to  quantitatively  evaluate  the  influence of crystal size and material on intercrystal scatter and parallax effects.   Materials and Methods:  For each of the 5 selected crystals (BGO, LSO, LYSO, LuAP, GSO), transport of  511  keV  photons  originating  from  a  point  source  and  incident  on  the  central  cry...

introduction: one of the most important parameters in x-ray ct imaging is the noise induced by detected scattered radiation. the detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. the magnitude and spatial distribution of the scattered radiation in x-ray ct should be quantified for development of robust scatter...

introduction: scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. accurate estimation of scatter in projection data of spect is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. methods: the objective of this paper is to develop and validate a scatter correction technique t...

To improve spatial resolution, PET systems are being developed with finer detector elements. Unfortunately, using smaller crystal sizes increases inter-crystal Compton scatter and bismuth x-ray and (to a lesser degree) electron escape crosstalk, causing positioning errors that lead to degradation of image contrast. We investigated the use of extremely thin (I 300 ym) lead strips for passive shi...

Introduction: One of the most important parameters in x-ray CT imaging is the noise induced by detected scattered radiation. The detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. The magnitude and spatial distribution of the scattered radiation in x-ray CT should be quantified for development of robust scatter...

Introduction: Scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. Accurate estimation of scatter in projection data of SPECT is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. Methods: The objective of this paper is to develop and validate a scatter correction technique ...

Introduction: In the last few decades, a lot of monte carlo codes have been introduced for medical applications. this is important because through simulation, we are fully independent of the spectral scattering factor that we are not able measure in real terms. The effect of the radiation energy, the dimension of the radiation field, the sensitive volume of the ion chamber on t...

one of methods of improvement of the material flow is cross docking that in is considered as a good method to reduce inventory and improve customer satisfaction. too, the vehicle routing problem is one of the important problems in distribution management and its goal is to find paths for delivering various cargos. therefore, this study was conducted in order to vehicle routing problem with cros...