Accurate, precise radiotherapy, including design and clinical implementation of the first low-Z target beam line for low dose (2-4 cGy) MV cone-beam CT, clinical applications of Monte Carlo, experimental benchmarking of Monte Carlo, treatment head simulation, beam modeling, treatment planning, x-ray plus electron radiotherapy (XPERT), proton therapy simulation and treatment planning, biological modeling of proton and light ion therapy, planning for a light ion therapy facility with research infrastructure, and precision radiotherapy and imaging of small mammals (PRISM).