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MLC positioning checks and calibration with a portal imaging system

Schiefer, Hans and Seelentag, Wolf W. and Roth, Jakob and Krusche, Bernd. (2008) MLC positioning checks and calibration with a portal imaging system. Zeitschrift für medizinische Physik, Vol. 18, H. 1. pp. 51-58.

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Official URL: http://edoc.unibas.ch/dok/A5261920

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Abstract

For checking the leaf positions of a MLC (Multi Leaf Collimator) images are acquired with an EPID (Electronic Portal Imaging Device) and then evaluated with a programme (MLC check) developed in-house. During image acquisition a Perspex tray with two metal markers of known position (in the radiation field) is inserted in the satellite tray holder. After determination of the marker positions within the image coordinate system, the image can be transformed to the radiation field coordinate system. This allows the exact determination of the leaf tip positions relative to the radiation field. This evaluation can be applied to images of arbitrary field shapes, provided they were acquired in the same geometry (EPID position, gantry and collimator angles). The entire measurement procedure is based on images in bmp (Windows Bitmap) format, with a 1024 x 1024 matrix and a pixel depth of 24 bit (8 bit per color channel). A suitable marker plate can be manufactured without sophisticated workload; thus the method may be easily and cost effectively adapted at other locations.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Hadronenphysik (Krusche)
UniBasel Contributors:Krusche, Bernd
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Elsevier
ISSN:0939-3889
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Mar 2012 14:27
Deposited On:22 Mar 2012 13:57

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