Ekstrand K E, Ferree C R, Dixon R L, Raben M
Radiology. 1979 Jul;132(1):201-3. doi: 10.1148/132.1.201.
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.
