Method and apparatus for optimizing an irradiation with a particle irradiation system having a plurality of jet outlets

A method for optimizing an irradiation with a particle irradiation unit (20) having a first jet outlet (31) and a second jet outlet (32) in the same treatment chamber, wherein after a first radiation with a first particle beam from the first beam outlet (31) comprises first steps (S5, S7) are performed, comprising generating an initial condition relative to the first jet outlet (31), wherein for a preparation or execution of one of the first irradiation subsequent second radiation with a second particle beam, which from the second jet outlet (32) is emitted, the second steps (S4, S6, S8) are carried out, characterized, that at least one of said second steps (S4, S6, S8) are carried out temporally before or temporally parallel to said first steps (S5, S7).