Achievement of uniform dose without overlap in multi-port treatment fields, including inter-port shaped blocks

The authors describe a technique for treating large areas with multiple ports without gaps or overlaps by rotating the therapy unit about the source. The overall effect is the same as if one large field were used with a single comprehensive set of precise shielding blocks. Minimal set-up time permits routine use of this method. Modifications for use with conventional megavoltage teletherapy units are discussed.