Half-value layer (HVL) is energy dependent on the photon, much as attenuation coefficient. Increasing penetrating of a photon stream causes an increase in substance's HVL. Before calculating HVL value, linear coefficient (μ) must be established. A review literature indicated that there presently no Monte Carlo-based sufficient tool for direct calculation value and computation suitable material ...

Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany Despite promising advances, attenuation correction of PET data remains challenging in PET/MRI. Known approaches to estimating attenuation maps from PET emission data take into account only true coincidences and fail to completely determine the attenuation map...

Shielding materials are extremely important in production or handling isotopes, nuclear reactors, accelerators, and medical centers, etc. The Monte Carlo simulation code Geant4 is one of the most common platforms for interaction radiation with matter. Therefore, this paper devoted to simulating partial absorption gamma-ray by Lead bronze alloys (Pb, Sn, Cu) different proportions using from 1.5 ...

UNLABELLED For quantitative PET information, correction of tissue photon attenuation is mandatory. Generally in conventional PET, the attenuation map is obtained from a transmission scan, which uses a rotating radionuclide source, or from the CT scan in a combined PET/CT scanner. In the case of PET/MRI scanners currently under development, insufficient space for the rotating source exists; the ...

In the hot environments of the anomalous X-ray pulsars and the soft gamma-ray repeaters, as indicated by their luminous, pulsed, quiescent X-ray emission, γ-rays generated from the inner gaps may have shorter attenuation lengths via two photon pair production than via magnetic photon splitting. The AXP/SGR environments may not be pairless, even if photon splitting could completely suppress one ...

We experimentally demonstrate a quantum cryptography system using two-photon entangled (EPR) states generated via the nonlinear process of spontaneous parametric down conversion pumped by a femtosecond laser. There are two major approaches in quantum cryptography which historically appeared almost simultaneously. One uses the quantum features of single photon states produced by signi cant atten...

introduction: osteoporosis is a bone disease in which there is a reduction in the amount of bone mineral content leading to an increase in the risk of bone fractures. the affected individuals not only have to go through lots of pain and suffering but this disease also results in high economic costs to the society due to a large number of fractures.  a timely and accurate diagnosis of this disea...

Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the 'self'-attenuation of photons emitted within the sample. The correction...

A Monte Carlo technique has been developed to simulate and correct for the effect of Compton scatter in 3-D acquired PET whole body imaging. The method utilizes the attenuation corrected and normalized, 3-D reconstructed image volume as the source intensity distribution for a photon-tracking Monte Carlo simulation. It is assumed that the number of events in each pixel of the image represents th...

Monte Carlo calculations are frequently used to analyse a variety of radiological science applications using low-energy (10-1000 keV) photon sources. This study seeks to create a low-energy benchmark for the MCNP Monte Carlo code by simulating the absolute dose rate in water and the air-kerma rate for monoenergetic point sources with energies between 10 keV and 1 MeV. The analysis compares four...