Modifying Dose At The Skin Surface and At Depth
A specific thickness of bolus can be applied to the skin to alter the dose received at depth in the tissue and on the skin surface. A typical example of this is the application of a defined thickness of bolus to a chest wall for post-mastectomy chest wall treatment, to increase the skin dose. The thickness of bolus applied is dependent on the skin dose required and the angle of incidence of the treatment beams. For example is oblique 6 MV beams are used for tangential pair, 1 cm of bolus effectively becomes 1.5 cm, i.e., ‘full bolus.’
When a full bolus is applied, bolus thickness equal to the depth of the build-up region removes the skin-sparing effect of a megavoltage x-ray beam.
Read more about this topic: Bolus (radiation Therapy)
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