Results 161 to 170 of about 4,830 (200)

An electronic portal imaging device for transit dosimetry

Physics in Medicine and Biology, 1997
An electronic portal imaging device has been designed and constructed. It consists of an array of 128 CsI scintillation crystals coupled to photodiodes which is scanned across the field in 4 seconds. The linac is operated at a dose rate of 400 cGy min-1 and the dose delivered for image acquisition is approximately 27 cGy.
SymondsTayler, JRN, Partridge, M, Evans, PM   +2 more
openaire   +4 more sources

Exit dose measurements by portal film dosimetry

Radiotherapy and Oncology, 1993
Portal in vivo dosimetry is a very attractive tool for patient dose measurements because of the large amount of information that portal film systems can easily collect, once positioned at the exit surface of the patient. The first step in the verification of the reliability of portal films as in vivo dosimeters is the evaluation of the agreement ...
C, Fiorino, A, del Vecchio, G M, Cattaneo, M, Fusca, B, Longobardi, P, Signorotto, R, Calandrino   +6 more
openaire   +2 more sources

Transmission dosimetry with a liquid-filled electronic portal imaging device

International Journal of Radiation Oncology Biology Physics, 1996
To assess the accuracy of transmission dose rate measurements for various phantom-detector geometries, performed with an electronic portal imaging device (EPID) and to compare these transmission dose rate values with exit dose rate data.Transmission dose rate values on the central beam axis and beam profiles were measured with an EPID consisting of a ...
Marion Essers, Ronald Boellaard, Marcel Van Herk   +2 more
exaly   +4 more sources

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

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

QA of dynamic MLC based on EPID portal dosimetry

Physica Medica, 2012
Dynamic delivery of intensity modulated beams (dIMRT) requires not only accurate verification of leaf positioning but also a control on the speed of motion. The latter is a parameter that has a major impact on the dose delivered to the patient. Time consumed in quality assurance (QA) procedures is an issue of relevance in any radiotherapy department ...
J, Richart, M C, Pujades, J, Perez-Calatayud, D, Granero, F, Ballester, S, Rodriguez, M, Santos   +6 more
openaire   +2 more sources

Monte Carlo simulation of the iView GT portal imager dosimetry

Applied Radiation and Isotopes, 2010
This work is mainly focused on developing a methodology to obtain portal dosimetry with an amorphous silicon electronic portal image device (EPID) by means of Monte Carlo simulations and experimental measures. According to this, pixel intensity values of portal images have been compared with dose measured from an ionization chamber and dose obtained ...
B, Juste, R, Miró, S, Diez, J M, Campayo, G, Verdú   +4 more
openaire   +2 more sources

Verification of treatment parameter transfer by means of electronic portal dosimetry

Medical Physics, 2004
Electronic portal imaging devices (EPIDs) are mainly used for patient setup verification during treatment but other geometric properties like block shape and leaf positions are also determined. Electronic portal dosimetry allows dosimetric treatment verification.
S M J J G, Nijsten, A W H, Minken, P, Lambin, I A D, Bruinvis   +3 more
openaire   +2 more sources

An effective correction algorithm for off‐axis portal dosimetry errors

Medical Physics, 2009
Portal dosimetric images acquired for IMRT pretreatment verification show dose errors of up to 15% near the detector edges as compared to dose predictions calculated by a treatment planning system for these off‐axis regions. A method is proposed to account for these off‐axis effects by precisely correcting the off‐axis output factors, which calibrate ...
Daniel W, Bailey, Lalith, Kumaraswamy, Matthew B, Podgorsak   +2 more
openaire   +2 more sources

Implementation of IMRT and VMAT using Delta4 phantom and portal dosimetry as dosimetry verification tools

AIP Conference Proceedings, 2016
In this study we analyzed and compared the dose distribution of different IMRT and VMAT plans with the intent to provide pre-treatment quality assurance using two different tools. Materials/Methods: We have used the electronic portal imaging device EPID after calibration to dose and correction for the background offset signal and also the Delta4 ...
Lulzime Daci, Partizan Malkaj
openaire   +1 more source