Feasibility study of patient positioning verification in electron beam radiotherapy with an electronic portal imaging device (EPID)

Abstract The purpose of this study is to demonstrate the feasibility of verification and documentation in electron beam radiotherapy using the photon contamination detected with an electronic portal imaging device. For investigation of electron beam verification with an EPID, the portal images are a...

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Bibliographic Details
Published in:Physica medica 2014-03, Vol.30 (2), p.215-220
Main Authors: Ramm, U, Köhn, J, Rodriguez Dominguez, R, Licher, J, Koch, N, Kara, E, Scherf, C, Rödel, C, Weiß, C
Format: Article
Language:English
Subjects:
Documentation
Electrical Equipment and Supplies
Electron
Electronic portal imaging device (EPID)
Electrons - therapeutic use
Feasibility Studies
Humans
Neoplasms - radiotherapy
Particle Accelerators
Patient Positioning - instrumentation
Phantoms, Imaging
Photons - therapeutic use
Radiation
Radiology
Radiotherapy
Signal-To-Noise Ratio
Verification
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Summary:Abstract The purpose of this study is to demonstrate the feasibility of verification and documentation in electron beam radiotherapy using the photon contamination detected with an electronic portal imaging device. For investigation of electron beam verification with an EPID, the portal images are acquired irradiating two different tissue equivalent phantoms at different electron energies. Measurements were performed on an Elekta SL 25 linear accelerator with an amorphous-Si electronic portal imaging device (EPID: iViewGT™ , Elekta Oncology Systems, Crawley, UK). As a measure of EPID image quality contrast (CR) and signal-to-noise ratio (SNR) are determined. For characterisation of the imaging of the EPID RW3 slabs and a Gammex 467 phantom with different material inserts are used. With increasing electron energy the intensity of photon contamination increases, yielding an increasing signal-to-noise ratio, but images are showing a decreasing contrast. As the signal-to-noise ratio saturates with increasing dose a minimum of 50 MUs is recommended. Even image quality depends on electron energy and diameter of the patient, the acquired results are mostly sufficient to assess the accuracy of beam positioning. In general, the online EPID acquisition has been demonstrated to be an effective electron beam verification and documentation method. The results are showing that this procedure can be recommended to be routinely and reliably done in patient treatment with electron beams.
ISSN:1120-1797
1724-191X
DOI:10.1016/j.ejmp.2013.06.001