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Summary
The dose discrepancy could be up to 10-15% due to the large difference
between the stopping powers of water and these higher-density materials
i.e. bone.
o
vertebrae, mandible, femoral heads…
For soft tissues and lung, the dose discrepancy is only about 1 to 2%
For air the discrepancy could be around 10-12%
o
air cavities in PTV, trachea, air cavities in intestines, rectum
o
Do we need to define air, is it OK with very low density soft
tissue/water???
April 2017
44
Slide inspired by N Reynaerts from his ESTRO 35 lecture