Beam spoiler

A beam spoiler is a piece of material, placed into the path of the photon beam in radiotherapy. The purpose of the spoiler is to reduce the depth of the maximum radiation dosage.^[1]

Composition

The beam spoiler is composed of a sheet of material which has a low atomic number,^[2] typically lucite, the thickness of which is varied according to the beam energy and the distance by which the radiation dose must be shifted.^[1]

Action

As the primary photon beam passes through the plate, secondary electrons are generated. The beam exiting the spoiler is a combination of the spoiler-attenuated photons and the spoiler-generated electrons. The electron component alters the depth dose in the buildup region in a way that depends on the photon beam energy, the field size, and the distance of the spoiler from the treatment surface.

References

^ ^a ^b Bentel, G.C. (1996) Radiation therapy planning p.103. McGraw-Hill Professional ISBN 0-07-005115-1 Retrieved September 2011.
^ Specht, L., Yahalom, J. (2010) Radiotherapy for Hodgkin Lymphoma p.125. Springer. ISBN 3-540-78455-1 Retrieved September 2011