In the 02 year we will continue cryogenic testing of the Stanford Medical Pion Generator (SMPG) along with improvement of the cryogenic instrumentation. The optical properties of the system will be studied, including effects of toroid alignment. Pion yields and electron and muon contamination for different targets and energies will receive further attention. Dosimetric studies in support of SMPG performance, understanding of the effects of inhomogeneities and simulated realistic patient anatomy, and treatment plan verification, will continue. These will include quality (via microdosimetric investigations) considerations. RBE and OER studies in vitro will be pursued for simple, as well as complex, geometries. These results, as well as detailed dosimetry measurements, will be incorporated into treatment planning calculations. Automation of SMPG operation and data accumulation will be further developed. Advantages, as well as limitations, of multiport pion irradiation will be further delineated.