The use of wedge filters to improve dose distribution with the partial rotation technique

Rotational arcs covering less than 360 degrees are frequently used in order to spare critical structures in radiation therapy; however, this results in a lack of dose uniformity in the target volume. Wedge filters can be used to restore dose uniformity in the treatment volume when limited arcs are employed. The authors emphasize the use of small rotational arcs (less than 90 degrees) in treating eccentrically located tumors such as those of the spinal cord and describe a simple model which can be used to calculate the wedge angle as a function of the arc angle.