Results 191 to 200 of about 7,705 (226)

A quality control test for electronic portal imaging devices

Medical Physics, 1996
A quality control (QC) test suitable for routine daily use has been developed for video based electronic portal imaging devices. It provides an objective and quantitative test for acceptable image quality on the basis of the high contrast spatial resolution and the contrast‐to‐noise ratio (CNR).
R, Rajapakshe, K, Luchka, S, Shalev
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An objective method for evaluating electronic portal imaging devices

Medical Physics, 1994
A statistical technique is described for analyzing the image of a contrast‐detail phantom acquired by a radiotherapy electronic portal imaging device. By using Student's t test, the image analysis algorithm computes which holes in the contrast‐detail phantom can be objectively resolved from the background signal.
L, Dong, A L, Boyer
openaire   +2 more sources

Prospective clinical evaluation of an electronic portal imaging device

International Journal of Radiation Oncology*Biology*Physics, 1996
To determine whether the clinical implementation of an electronic portal imaging device can improve the precision of daily external beam radiotherapy.In 1991, an electronic portal imaging device was installed on a dual energy linear accelerator in our clinic.
J M, Michalski, M V, Graham, W R, Bosch, J, Wong, R L, Gerber, A, Cheng, A, Tinger, R K, Valicenti   +7 more
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Portal dose measurements with electronic portal imaging devices

2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149), 2002
Summary form only given. Measuring portal dose with an electronic portal imaging device in external beam radiotherapy can be used to perform routine dosimetric quality control checks on linear accelerators and to verify treatments (in vivo dosimetry). For both the fluoroscopic CCD camera based systems and the systems based on an array of liquid-filled ...
openaire   +1 more source

Characterization of a high-elbow, fluoroscopic electronic portal imaging device for portal dosimetry

Physics in Medicine and Biology, 1999
The application of a newly developed fluoroscopic (CCD-camera based) electronic portal imaging device (EPID) in portal dosimetry is investigated. A description of the EPID response to dose is presented in terms of stability, linearity and optical cross-talk inside the mechanical structure.
Boer, J.C.J. de, Heijmen, B.J.M., Pasma, K.L., Visser, A.G.   +3 more
openaire   +4 more sources

Portal dose measurement in radiotherapy using an electronic portal imaging device (EPID)

Physics in Medicine and Biology, 1995
Physical characteristics of a commercially available electronic portal imaging device (EPID), relevant to dosimetric applications in high-energy photon beams, have been investigated. The EPID basically consists of a fluorescent screen, mirrors and a CCD camera.
B J, Heijmen, K L, Pasma, M, Kroonwijk, V G, Althof, J C, de Boer, A G, Visser, H, Huizenga   +6 more
openaire   +2 more sources

A new approach in the design of electronic portal imaging devices for portal dosimetry in radiotherapy

Physica Medica, 2014
A CCD-based EPID using new crystal-assembly X-ray (CAX) converters is investigated for radiotherapy dosimetry. The proposed EPID design consists in replacing the common phosphor X-ray converters of current CCD-based EPIDs with high-stopping-power CAX converters.
J N, Badel, D, Partouche-Sebban, I, Abraham, C, Carrie   +3 more
openaire   +2 more sources

Lung compensator design using an electronic portal imaging device

Medical Dosimetry, 1999
Using a liquid filled electronic portal imaging device (EPID) installed on a linear accelerator and a composite chest phantom, exit dose measurements were carried out to establish an empirical relationship between the pixel values of the imaging detector and the corresponding equivalent thickness of the overlying phantom material.
H, Parsaei, S, Hussein, E, el-Khatib
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A multipurpose phantom for use with electronic portal imaging devices

Physics in Medicine and Biology, 1995
A simple, low-cost, multipurpose phantom has been designed for use with electronic portal imaging devices (EPIDS). Making use of the high spatial resolution of an EPID, together with the built in software tools for measuring distances, it is possible to verify x-ray/light field size and congruence, at any gantry angle, for fields up to 200 mm x 200 mm.
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Verification of the optimal backscatter for an aSi electronic portal imaging device

Physics in Medicine and Biology, 2005
Electronic portal imaging devices (EPIDs), currently used for determining proper patient placement during irradiation in a radiotherapy treatment, can also be used as dosimeters. However, the Varian aS500 portal imager exhibits dosimetric artefacts caused by non-uniform backscatter from mechanical support structures located behind the imager.
Joseph A, Moore, Jeffrey V, Siebers
openaire   +2 more sources