Comparison of static and dynamic treatment modes for the pion therapy beam at LAMPF

Focused beams of negative pions have been developed for dynamic treatments at the Biomedical Facility in Los Alamos. In dynamic treatment, the patient is scanned under a focused pion beam. Using measured depth-dose distributions and off-axis dose distributions, we are able to find a scanning function that allows the best coverage of the target volume. Calculation of dose distributions for dynamic beam treatment plans, both in a water phantom and in a patient, illustrates the superiority of dynamic over static treatments that use broad, essentially parallel beams in shaping the dose distribution to the target volume.