Physical factors such as photon attenuation degrade image quality and quantitative accuracy in single-photon emission computed tomography (SPECT). It is often considered (especially in situations with non-uniform attenuation and distance-dependent spatial resolution (DDSR)) that adequate compensation for the effects of these physical factors requires data acquired over 2 . However, as the analy...

Background:In diagnostic radiology lead apron, are usually used to protect patients and radiology staff against ionizing radiation. Lead apron is a desirable shield due to high absorption and effective attenuation of x-ray photons in the diagnostic radiology range.Objective: Although lead aprons have good radiation protection properties, in recent years, researchers have been looking for altern...

Detrimental effects to quantitative interpretation of Mie and laser-induced fluorescence images of hollow-cone sprays were investigated. The attenuation of the laser beam leads to locally unknown intensities rendering it impossible to obtain high-fidelity images of these sprays. Two strategies that use bidirectional illumination of the spray are discussed and evaluated. Conditions for which a b...

This study has investigated the relationship between linear attenuation coefficients (mu) and Hounsfield units (HUs) for six materials covering the range of values found clinically. Narrow-beam mu values were measured by performing radionuclide transmission scans using (99m)Tc, (123)I, (131)I, (201)Tl and (111)In. The mu values were compared to published data. The relationships between mu and H...

Borrmann and Hartwag [1] have shown that the anomalously high transmission of x-rays through perfect crystals in 2-beam diffraction is further enhanced when a third set of planes is brought to its diffracting position. Simultaneous 3-beam diffraction then takes place. That discovery has stimulated large numbers of investigations, in many of which major emphasis has been placed on the spectacula...

The presence of metallic prostheses during external beam radiotherapy of malignancies in the pelvic region has the potential to strongly influence the dose distribution to the target and to tissue surrounded by the prostheses. This study systematically investigates the perturbation effects of unilateral titanium prosthesis on 6 and 15 MV photon beam dose distributions using Gafchromic EBT2 film...

Contribution of heterotrophic marine bacteria (HB) to the particulate beam attenuation coefficient (cp) was estimated as a function of latitude in diverse marine regions. Calculations were based on surface measurements (0 to 20 m depth) of bacterial abundance and biovolume, physiooptical empirical relationships, and light scattering models. Relative contribution of spherical HB to cp (cHB/cp) w...

We show that the enhanced directivity phenomenon for light passing through a subwavelength aperture in a silver film with corrugations on the exit face, is due to a leaky wave that decays exponentially from the aperture. We show quantitatively that the field along the interface of the silver film is dominated by the leaky wave, and that the radiation of the leaky wave, supported by the periodic...

With the new data collected with polarimetric radars comes a set of new data quality issues and artifacts. It is important for these artifacts to be recognized and understood as such, thereby allowing operational meteorologists to focus on the interpretation of the physically important observations. In this third part of the series, artifacts found in polarimetric radar data are described and e...

background and aims. cone-beam computed tomography (cbct) is an imaging system which has many advantages over computed tomography (ct). in ct scan, hounsfield unit (hu) is proportional to the degree of x-ray attenuation by the tissue. in cbct, the degree of x-ray attenuation is shown by gray scale (voxel value). the aim of the present study was to investigate the relationship between gray scale...