Scatter dose for wedged fields |
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Authors: | L H Brown R L Siddon B E Bj?rngard |
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Institution: | Joint Center for Radiation Therapy, Harvard Medical School, Boston, MA 02115. |
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Abstract: | The behaviour of scatter dose in 4 and 8 MV wedged x-ray beams has been studied by calculating scatter-to-primary dose ratios (SPR) and comparing these with SPR for non-wedged beams. On the central axis the SPR for wedged and non-wedged beams differ only by a few per cent, a difference which increases slightly with wedge angle and field size. In other points within the field the differences are larger but generally less than 3% of the total dose on the central axis at the same depth. The product rule for points that do not lie in a principal plane is valid within the same limits as for non-wedged beams. |
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