نتایج جستجو برای: optical collimator

تعداد نتایج: 269265  

Journal: :Physica Medica 2021

Multi-slat prompt-gamma camera is a promising tool for range monitoring during proton therapy. We report the results of comprehensive simulation study analyzing precision which possible to reach with this in determination position distal edge Bragg peak. For first time we include optical photons. The beam (single pencil beam, 130 MeV, 10 ns bunch period, total 1·108 protons) interacting polymet...

2013
Hirotsugu Kashiwagi Nobumasa Miyawaki Satoshi Kurashima Susumu Okumura

We are developing an acceptance measurement system to evaluate the matching of the emittance of an injection beam to the acceptance of the AVF cyclotron. The system is composed of a phase-space collimator in the low energy section and beam intensity monitors which are installed just after the phase space collimator and in the high energy section. The phase-space collimator, which consists of tw...

Journal: :Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine 2000
Y C Cheung K N Yu R T Ho C P Yu

The accuracy of the dose planning system (Leksell GammaPlan) used in Gamma Knife (model-B) radiosurgery was verified using both the GafChromic films MD-55 (improved) and the EGS4 Monte Carlo technique. The Monte Carlo technique was employed to calculate the dose distribution along the x-, y- and z-axes when a single shot with opening of all 201 sources was delivered at the centre of a simulated...

2012
Seungryong Cho Taewon Lee Jonghwan Min Hyekyun Chung

We proposed a novel scanning method for low-dose computed tomography (CT) that uses an oscillating multi-slit collimator between the x-ray source and the patient. It can be thought as a realization of sparse data sampling that does not require a fast x-ray power switching. A simulation study was performed based on experimentally acquired microCT data of a mouse to demonstrate the feasibility of...

Journal: :IEEE transactions on medical imaging 1993
Gengsheng Lawrence Zeng Grant T. Gullberg Ronald J. Jaszczak Jianying Li

Fan-beam collimators are used in single-photon-emission computed tomography (SPECT) to improve the sensitivity for imaging of small organs. The disadvantage of fan-beam collimation is the truncation of projection data surrounding the organ of interest or, in those cases of imaging large patients, of the organ itself, producing reconstruction artifacts. A spatially varying focal length fan-beam ...

Journal: :Journal of nuclear medicine technology 1999
R S Benjamin A Amro M I El-Desouki

OBJECTIVE This study compared the 123I thyroid uptake measurements obtained from a gamma camera fitted with a low-energy all-purpose (LEAP) collimator to those obtained from a thyroid uptake probe and gamma camera fitted with a pinhole (PH) collimator. METHODS Thirty-one patients (27 female and 4 male patients) were studied for comparison between a probe and a gamma camera fitted with LEAP co...

Journal: :Optics express 2012
Dejan Grabovičkić Pablo Benítez Juan C Miñano

A metal-less RXI collimator has been designed using the Simultaneous multiple surface method (SMS). Unlike conventional RXI collimators, whose back surface and parts of the front surface have to be metalized, this collimator is completely metal-free, made only of plastic (PMMA). The collimator’s back surface is designed as a grooved surface providing two TIR reflections for all rays impinging o...

Journal: :International journal of radiation oncology, biology, physics 2010
Hu Zhou Manuel Rodriguez Fred van den Haak Geoffrey Nelson Rahil Jogani Jiali Xu Xinzhi Zhu Yongjiang Xian Phuoc T Tran Dean W Felsher Paul J Keall Edward E Graves

PURPOSE To report on the physical aspects of a system in which radiotherapy functionality was added to a micro-computed tomography (microCT) scanner, to evaluate the accuracy of this instrument, and to and demonstrate the application of this technology for irradiating tumors growing within the lungs of mice. METHODS AND MATERIALS A GE eXplore RS120 microCT scanner was modified by the addition...

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2000
M K O'Connor L K Leong R J Gibbons

UNLABELLED The aim of this study was to determine the reproducibility of measurements of the size and severity of myocardial defects from 99mTc sestamibi cardiac phantom studies performed on multiple different gamma camera systems. METHODS A total of 250 gamma camera systems were evaluated over a 5-y period as part of the validation process of multiple multicenter trials. Each laboratory perf...

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