Conventional single photon emission computed tomography (SPECT) collimators are not suitable for 511 keV imaging. In order to use a SPECT system for single positron emission tomography (SPET), we need to design high-efficiency collimators capable of absorbing 511 keV photons. Slit slat (SS) collimators have been proposed for this purpose even though the optimization of such collimators has not ...

The aim of this study was to analyze the interobserver agreement visual and quantitative assessment cardiac 123I-metaiodobenzylguanidine scintigraphy. Methods: Planar images were acquired using a low-energy collimator. heart-to-mediastinum (HM) ratio adjusted for use collimator, published formula. Interpretation undertaken both visually after addition HM ratios. Image findings...

Introduction: Gamma cameras are proposed for online range verification and treatment monitoring in proton therapy.  An Analytical formula was derived and validated for sensitivity of a slit collimator based on the photon fluence concept. Methods: Fluence formulation was generalized for photons distribution function and solved for high-energy point sources. The...

A collimator simulator which is an accessory in radiology equipment, has been made. This was created as a learning medium to complete students' understanding studying x-rays part of electromagnetic waves. The research divided into two stages, namely the manufacture simulators and implementation teaching materials. equipped with blades that are used limit radiation field area. In this study, lam...

The problems caused by miniaturization of the goniometer are discussed from the viewpoint of the stress error caused by mis-setting of the specimen and misalignment of the collimator and detector for the Q assembly X-ray stress analyzer using a position sensitive detector. The stress errors were calculated using a model and a simulation method. It was found that they tend to increase with the d...

The dose distributional properties of a p(50) Be neutron beam using a continuously variable multi-leaf collimator are presented and compared with a 6 MV photon beam. The differences in physical dose delivery between these two radiation modalities are generally insignificant for radiation therapy, and stringent comparisons of neutron and photon treatments should therefore be possible. The flexib...

In the present paper, we propose a method to fabricate a ‘‘micro-collimator’’ with a thickness of 15mm. A commercially available PADC film with a thickness of 100mm was first chemically etched with NaOH/ethanol solution to obtain a thin PADC film. This thin PADC film was then irradiated by 5MeV a particles through a ‘‘macro-collimator’’ with a thickness of 5mm and a hole diameter of 1mm. This P...

In single photon emission computed tomography (SPECT), a varying-focal-length cone-beam collimator can be used to reduce the truncation problem and to maintain sensitivity when imaging the organ of interest. The collimator is constructed so that the collimator holes focus to a circular symmetric, spatially varying, focal point function. The focal length increases radially from the shortest foca...

The performance of future linear colliders are limited by the effect of short-range collimator wakefields on the beam. The beam quality is sensitive to the positioning of collimators at the end of the linac. The determination of collimator wakefields has been difficult, largely because of the scarcity of measurement data, and of the limitation of applicability of analytical results to realistic...