The Overall Objective of this project is to develop, demonstrate, and test several different techniques which improve control over conformal therapy dose distributions. At present, dosimetric modification of conformal plans is typically limited to geometric modification (e.g., field shape and beam directions). Recently, computer-controlled treatment machines have made possible (technically) the use of more sophisticated types of dose distribution modification techniques ranging from static field shaping of flat fields to the use of conformal multileaf-collimated fields with individualized beam intensity modulation. This project will investigate the use of beam intensity modulation techniques which can be achieved with the currently available computer-controlled treatment machines, including computer-controlled multileaf collimator (MLC) motion and computer-controlled point-scanned electron beams. Field shaping and intensity modulation techniques will be developed, their clinical utility will be analyzed and compared, and their use clinically implemented. This project will significantly improve the control we have over dose distribution formation and delivery, and will determine realistic limitations on the flexibility of deliverable dose distributions which can be designed by the plan optimization project (project 1) and delivered by the clinical study (project 4).