FURTHER INVESTIGATIONS OF PHYSICAL ASPECTS OF MULTIPLE FIELD RADIATION THERAPY.

Further investigations of dose distributions in the junction volumes between contiguous fields have shown that "gaps" calculated for use when treatments are delivered through unilateral adjacent fields2 are applicable to multifield techniques incorporating opposing fields.Using the concept of decrement lines described by Orchard,3 total junction doses may be increased in a controlled manner to compensate for increased treatment time to the junction volume. The dose distribution in the junction volume is compared with that along the central axis of the contributing fields for 4 commonly used contiguous field combinations.