The inverse compensating filter.
When a single-field technique is used in megavoltage x-ray therapy, a uniform entrance dose is often required. If there is a large variation in source-to-surface distance over the field, an inverse type of compensating filter is necessary to achieve entrance dose uniformity. The production and utilization of these filters is discussed.
D005374:Filtration / Q000295:instrumentation*; D006801:Humans; D011878:Radiotherapy / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy