Medical Physics Research Today is a free monthly online journal that collates and summarizes the latest research about Medical Physics, including details on medicine, radiotherapy, biomechanics, medical imaging.

A theoretical model evaluating the angular distribution of luminescence emission in X-ray scintillating screens.

Kandarakis I, Cavouras D, Nikolopoulos D, Episkopakis A, Kalivas N, Liaparinos P, Valais I, Kagadis G, Kourkoutas K, Sianoudis I, Dimitropoulos N, Nomicos C, Panayiotakis G

Department of Medical Instruments Technology, Technological Educational Institution (TEI) of Athens, Agiou Spyridonos, Aigaleo, 12210 Athens, Greece. kandarakis@teiath.gr

The aim of this study was to examine the angular distribution of the light emitted from radiation-excited scintillators in medical imaging detectors. This distribution diverges from Lambert's cosine law and affects the light emission efficiency of scintillators, hence it also affects the dose burden to the patient. In the present study, the angular distribution was theoretically modeled and was used to fit experimental data on various scintillator materials. Results of calculations revealed that the angular distribution is more directional than that predicted by Lambert's law. Divergence from this law is more pronounced for high values of light attenuation coefficient and thick scintillator layers (screens). This type of divergence reduces light emission efficiency and hence it increases the incident X-ray flux required for a given level of image brightness.

Published 8 February 2006 in Appl Radiat Isot, 64(4): 508-19.
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