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Diode Response Correction in Large Photon Fields

<p>The energy dependent response of silicon diodes in photon beams is a known problem. A new approach to solve this problem is by correcting the response, a response model was suggested by Yin et al. (2002, 2004), and later refined by Eklund and Ahnesjö (2009). In this work a prototype software was developed to calculate correction factors for arbitrary measurement points in MLC shaped fields using fluence pencil beam kernels to calculate the spectra used by the model of Eklund and Ahnesjö (2009). This work investigate this approach for large field sizes. It was found that the relative dose measurements of the corrected unshielded diode agreed with ionization chamber measurements within 1% at the central axis. Measurements made off axis (square and irregular fields) agreed within 2%, better results were achieved within the fields when the off axis beam softening were taken into consideration. This work has also shown that this new approach is an alternitive to shielded diodes and that corrected diodes will in some cases provide more reliable results.</p>

Identiferoai:union.ndltd.org:UPSALLA/oai:DiVA.org:su-42951
Date January 2010
CreatorsVorbau, Robert
PublisherStockholm University, Medical Radiation Physics (together with KI)
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeStudent thesis, text

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