Basic Treatment Planning
Penumbra • Penumbra is often defined as the distance between the 20% and the 80% (10% and 90%) isodose lines • The penumbra is the region near the edge of the field where the dose falls off rapidly Width depends on Size of ‘source’
SSD/FSD (Lower SSD, higher penumbra) Energy (Increasing penumbra with increasing energy: increased field size)
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