This paper discusses the use of small pixels in a spinning CdZnTe single photon emission computed tomography (SPECT) camera that is mounted with a parallel slat collimator. In a conventional slat collimation configuration, there is a detector pixel between two adjacent collimator slats. In our design, the pixel size is halved. That is, there are two smaller pixels to replace a regular pixel bet...

The SLC final-focus system accommodates 29 fixed or adjustable collimators for machine protection and background reduction. By amplifying pulse-to-pulse orbit variations and by generating emittance growth, collimator wake fields may degrade the beam quality at the interaction point (IP). In the SLC final focus, collimator halfapertures are larger than the bunch length, so that the standard coll...

In Winston-Lutz (WL) tests, the isocenter of a linear accelerator (linac) is determined as the intersection of radiation central axes (CAX) from multiple gantry, collimator, and couch angles. It is well known that the CAX can wobble due to mechanical imperfections of the linac. Previous studies suggested that the wobble varies with gantry and collimator angles. Therefore, the isocenter determin...

This study was aimed at comparing the sensitivity and hot and cold contrasts obtained when imaging the PICKER thyroid phantom using gamma cameras fitted with either their ultra-high or high-resolution low-energy parallel hole collimator. Seventeen camera models from Elscint, General Electric, Siemens and Sopha Medical Vision were involved in the study for a total of 30 cameras and 52 camera hea...

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...