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...

Gaseous discharge light sources are leading candidates for generating 13.5 nm wavelengths needed for next-generation optical lithography. Electrode debris reaching the first collector optic is a serious concern for device lifetime and cost of ownership. This paper describes the experimental setup and initial data obtained for testing secondary-plasmabased debris mitigation for EUV gas discharge...

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...

A dosimetry system based on Al2O3:C radioluminescence (RL), and RADPOS, a novel 4D dosimetry system using microMOSFETs, were used to measure total scatter factors, (S(c,p))(f(clin))(det), for the CyberKnife robotic radiosugery system. New Monte Carlo calculated correction factors are presented and applied for the RL detector response for the 5, 7.5 and 10 mm collimators in order to correct for ...

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...