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Proceedings Paper

Use Of Scattered Radiation Measurements In Radiotherapy Dose Calculations Based On Computed Tomographic (CT) Images
Author(s): John W. Andrew; J. Van Dyk; H. E. Johns
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Paper Abstract

One of the major uses of CT information is in dose calculations when the patient is treated with high energy radiation. Variations in electron density in tissue will affect both the primary and scattered radiation. The primary can easily be dealt with but the scattered component is very difficult to take into account. One requires detailed information on the relative importance of scatter from different volume elements. We have studied the scatter phenomenon in a water phantom irradiated by 60Co radiation. We measured the effect on the dose to a point in the phantom when small volumes of water in the phantom are replaced with styrofoam which is nearly air equivalent. In this way we have obtained information on the amount of scattered dose from different parts of the phantom. However, the experimental procedure of replacing water with air has a perturbing effect on scatter from other regions of the phantom. In extreme cases, removal of scattering medium can actually increase the overall scattered dose to the point of measurement. In this paper we will present one set of experimental data and show an example of its use in a dose calculation for a nonhomogeneous phantom.

Paper Details

Date Published: 6 July 1979
PDF: 6 pages
Proc. SPIE 0173, Application of Optical Instrumentation in Medicine VII, (6 July 1979); doi: 10.1117/12.957162
Show Author Affiliations
John W. Andrew, University of Toronto (Canada)
J. Van Dyk, University of Toronto, (Canada,)
H. E. Johns, University of Toronto, (Canada)


Published in SPIE Proceedings Vol. 0173:
Application of Optical Instrumentation in Medicine VII
Joel E. Gray, Editor(s)

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