Results 211 to 220 of about 66,716 (273)

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

Evaluation of set-up errors and determination of set-up margin in pelvic radiotherapy by electronic portal imaging device (EPID)

Journal of Radiotherapy in Practice, 2020
The error in set-up of patients is an inherent part of treatment processes. The positioning errors can be used to determine the margins of the planning target volume (PTV) to cover the target volume, while minimising the radiation dose delivered to ...
Vajiheh Vejdani Noghreiyan, S. Nasseri, K. Anvari, M. Naji, M. Momennezhad   +4 more
semanticscholar   +1 more source

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
openaire   +2 more sources

An electronic portal imaging device as a physics tool

Medical Dosimetry, 1997
An electronic portal imaging device (EPID) can be used not only to acquire megavoltage patient images but also to measure certain radiation beam parameters of the linear accelerator. EPID images can be used to verify field junctions, center of collimator rotation, or radiation vs. light field coincidence.
A, Curtin-Savard, E B, Podgorsak
openaire   +2 more sources

Modeling the temporal-spatial nature of the readout of an Electronic Portal Imaging Device (EPID).

Medical Physics (Lancaster), 2020
PURPOSE In real-time electronic portal imaging device (EPID) dosimetry applications where on-treatment measured transmission images are compared to an ideal predicted image, ideally a tight tolerance should be set on the quantitative image comparison in ...
P. Abbasian, P. Mccowan, D. Rickey, E. van Uytven, B. McCurdy   +4 more
semanticscholar   +1 more source

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
openaire   +2 more sources

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

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
openaire   +2 more sources

Assessment of Multi-leaf Collimator Positional Accuracy Using Radiochromic EBT3 Film and an Electronic Portal Imaging Device

, 2020
This study aimed to evaluate multi-leaf collimator (MLC) positional accuracy by using an electronic portal imaging device (EPID) and radiochromic EBT3 film. Furthermore, the MLC’s positional accuracy at different gantry and collimator angles of a Siemens
Forough Nikeghbali, A. Nickfarjam, F. Shirani, N. Goushbolagh, Nasim Namiranian, Bagher Farhood, M. Shabani, Kazem Vakili   +7 more
semanticscholar   +1 more source

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