Results 171 to 180 of about 10,990 (209)

Portal dosimetry of small unflattened beams

Physics in Medicine & Biology, 2021
Abstract We developed and validated a dedicated small field back–projection portal dosimetry model for pretreatment and in vivo verification of stereotactic plans entailing small unflattened photon beams.
Aldemar Torres Valderrama, Igor Olaciregui-Ruiz, Patrick González, Thijs Perik, Ben Mijnheer, Anton Mans   +5 more
openaire   +2 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

In-vivo portal dosimetry by an ionization chamber

Physica Medica, 2005
As all methods for in-vivo dosimetry require special efforts many physicists are often discouraged in verifying the middle dose in a patient along the beam central axis. This work reports a practical method for the determination of the middle dose value, D(m), on the central beam axis, using a signal S(t), obtained by a small thimble ion-chamber ...
Piermattei, Angelo, Grimaldi, Luca, D'Onofrio, Guido, Cilla, Savino, Viola, Pietro, Craus, Maurizio, Fidanzio, Andrea, Azario, Luigi, Deodato, Francesco, Macchia, Gabriella, Morganti, Alessio Giuseppe   +10 more
openaire   +3 more sources

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   +3 more sources

Automaticin vivoportal dosimetry of all treatments

Physics in Medicine and Biology, 2013
At our institution EPID (electronic portal imaging device) dosimetry is routinely applied to perform in vivo dose verification of all patient treatments with curative intent since January 2008. The major impediment of the method has been the amount of work required to produce and inspect the in vivo dosimetry reports (a time-consuming and labor ...
Van Herk, Marcel, Olaciregui-Ruiz, I, Rozendaal, R, Mijnheer, B, van Herk, M, Mans, A   +5 more
openaire   +4 more sources

Breast in vivo dosimetry by a portal ionization chamber

Medical Physics, 2007
This work reports a practical method for the determination of the in vivo breast middle dose value, , on the beam central axis, using a signal , obtained by a small thimble ion chamber positioned at the center of the electronic portal imaging device, and irradiated by the x‐ray beam transmitted through the patient.
Grimaldi, Luca, D'Onofrio, Guido, Cilla, Savino, Fidanzio, Andrea, Stimato, Gerardina, Azario, Luigi, Deodato, Francesco, Macchia, Gabriella, MORGANTI, ALESSIO GIUSEPPE, Piermattei, Angelo   +9 more
openaire   +3 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

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

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

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