These teachings serve to facilitate radiating a treatment target (105) in a patient (104) during a radiation treatment session with a radiation treatment platform (114) having a moving source of radiation (115) and using an optimized radiation treatment plan (113). These teachings in particular provide for configuring the radiation treatment platform (114) in a half-fan trajectory arrangement. These teachings then provide for beginning the radiation treatment session with the source of radiation (115) in a first location and an isocenter (301) for the treatment target (105) in a first position. Then, during the radiation treatment session, these teachings provide for moving the source of radiation (115) from that first location in synchronization with moving the isocenter (301) from the aforementioned first position.