Design considerations for a proton therapy beamline with an energy degrader

During the development of the Northeast Proton Therapy Center (NPTC) beamline, several design issues have been identified which are of interest in the generic design of a beamline for similar types of facilities. There are beneficial beamline optics conditions to be imposed when the beamline is used with an energy degrader and when the beamline must transport a beam to be used with a gantry that is coupled with a beam delivery system that can support both pencil beam scanning and scattering methods to spread out the beam. These conditions will be discussed and some results of calculational investigation for the NPTC beamline will be reported.