نتایج جستجو برای: pixelated collimator

تعداد نتایج: 3420  

Journal: :Medical physics 2012
J Fan Q Xu L Wang L Jin J Li T Lin S Hayes T Tam C Ma

PURPOSE There are two collimation systems associated with the CyberKnife system, the fixed cone collimator and the Iris collimator. The Iris collimator is used more frequently because of its superior flexibility. However, sometimes treatments have to be canceled or postponed due to Iris collimator mechanical failures. The purpose of this study is to investigate the feasibility of switching coll...

2012
Yuefeng Zhu

Digital Signal Processing Methods for Pixelated 3-D Position Sensitive Room-Temperature Semiconductor Detectors by Yuefeng Zhu

2018
Ming‐Hsien Li Sheng‐Fang Huang Chih‐Chieh Chang Jang‐Chun Lin Jo‐Ting Tsai

PURPOSE Hypofractionated radiotherapy can reduce treatment durations and produce effects identical to those of conventionally fractionated radiotherapy for treating prostate cancer. Volumetric arc radiotherapy (VMAT) can decrease the treatment machine monitor units (MUs). Previous studies have shown that VMAT with multileaf collimator (MLC) rotation exhibits better target dose distribution. Thu...

Journal: :Medical physics 2007
Edward E Graves Hu Zhou Raja Chatterjee Paul J Keall Sanjiv Sam Gambhir Christopher H Contag Arthur L Boyer

Treatment of small animals with radiation has in general been limited to planar fields shaped with lead blocks, complicating spatial localization of dose and treatment of deep-seated targets. In order to advance laboratory radiotherapy toward what is accomplished in the clinic, we have constructed a variable aperture collimator for use in shaping the beam of microCT scanner. This unit can image...

1994
S V Guru J D Valentine D K Wehe G F Knoll

To develop a second generation gamma-ray camera for industrial applications, various multiple-hole collimator designs that meet high-energy, high-intensity and far-eld imaging requirements have been studied. The collection of parallel holes each parallel to one another (parallel-hole, parallel collimator) is ineeective for imaging high energy far-eld sources, whereas a collimator with parallel ...

2002
Peter Tenenbaum

We summarize the formalism of collimator wakefields and their effect on beams that are near the center of the collimator gap, and apply the formalism to the TESLA, NLC, and CLIC collimation systems. Collimator Wakefield Calculations for ILC-TRC Report

Journal: :Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2015
Casper Beijst Mattijs Elschot Max A Viergever Hugo W A M de Jong

UNLABELLED In SPECT using high-energy photon-emitting isotopes, such as (131)I, parallel-hole collimators with thick septa are required to limit septal penetration, at the cost of sensitivity and resolution. This study investigated a parallel-hole collimator with cone-shaped holes, which was designed to limit collimator penetration while preserving resolution and sensitivity. The objective was ...

Journal: :Journal of the Optical Society of America. A, Optics, image science, and vision 2016
Tomáš Tyc Stephen Oxburgh Euan N Cowie Gregory J Chaplain Gavin Macauley Chris D White Johannes Courtial

We present a design for an omnidirectional transformation-optics (TO) cloak comprising thin lenses and glenses (generalized thin lenses) [J. Opt. Soc. Am. A33, 962 (2016)1084-7529JOAOD610.1364/JOSAA.33.000962]. It should be possible to realize such devices in pixelated form. Our design is a piecewise nonaffine generalization of piecewise affine pixelated-TO devices [Proc. SPIE9193, 91931E (2014...

Journal: :Annals of nuclear medicine 2006
Nobutoku Motomura Kyojiro Nambu Akihiro Kojima Seiji Tomiguchi Koichi Ogawa

Due to the collimator aperture, spatial resolution of SPECT data varies with source-to-detector distance. Since the radius of detector rotation is bigger when scanning larger patients, spatial resolution is degraded in these cases. Emitted gamma rays travel not only along the central axis of the collimator hole but also off-axis due to the collimator aperture. However, an off-axis ray at one an...

2010
Tarek Halabi Bruce Faddegon

We design a practical procedure for measuring translational and rotational misalignment of graticule with collimator axis of rotation and collimator jaws, respectively. The procedure's quantitative results are accurate to less than 0.2 mm (at isocenter) and do not assume alignment of radiation focal spot with collimator axis of rotation. When provided with these quantitative results, the manufa...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید