Material inserts for radiation therapy

A computer-implemented method of radiation treatment, the method comprising:

• accessing, from a memory of a computer system, a radiation treatment plan that prescribes a distribution of a dose to be delivered to a target in a patient by a plurality of beams emitted from a nozzle of a radiation treatment system during the radiation treatment;
• and
• controlling the nozzle during the radiation treatment to aim the plurality of beams at a cranial immobilization device worn by the patient during the radiation treatment, the cranial immobilization device comprising:
• a shell component comprising a layer of material in a shape of a helmet to accommodate the patient's head during the radiation treatment, wherein the shell component lies in a path of the plurality of beams during the radiation treatment to degrade energies of the plurality of beams for range compensation to locate a peak of a dose distribution of respective ones the plurality of beams at respective distal portions of the target in the patient;
• a plurality of material inserts, wherein each material insert of the plurality of material inserts lies on the path of at least one beam of the plurality of beams during the radiation treatment, wherein each material insert of the plurality of material inserts has a respective non-uniform thickness measured in a direction of the path of the respective beam for range modulation of the respective beam to deliver the dose distribution between respective distal and proximal portions of the target in the patient prescribed in a radiation treatment plan for the radiation therapy, and wherein the non-uniform thickness of the respective ones of the plurality of material inserts is based on a three-dimensional (3D) model of the target created from a plurality of two-dimensional (2D) images of the target;
• and
• a scaffold component disposed in the shell component and operable to hold the plurality of material inserts at respective locations in the shell component in place relative to the patient,
• wherein said controlling comprises:
• aiming the nozzle at a first material insert of the plurality of material inserts and then turning on and emitting a first beam at the first material insert;
• and
• turning off the first beam and aiming the nozzle at a second material insert of the plurality of material inserts and turning on and emitting a second beam at the second material insert.