Dynamic target masker in radiation treatment of multiple targets

An external-beam radiation treatment system comprising:

• a radiation treatment device including:
• a rotatable gantry including a treatment head and a multi-leaf collimator (MLC), wherein the MLC is configured to shape a radiation beam emitted from the treatment head;
• and
• a control unit configured to:
• control rotation of the rotatable gantry;
• control emission of the radiation beam from the treatment head;
• and
• control a shape of the radiation beam via the MLC;
• one or more processors;
• and
• a non-transitory computer readable medium storing a plurality of instructions that when executed control the one or more processors to determine MLC leaf sequences in a radiation treatment plan for treating a plurality of target volumes within a treatment area of a patient, the instructions comprising:
• receiving, by a computer system, information about a first target volume and a second target volume of the plurality of target volumes;
• receiving, by the computer system, the radiation treatment plan including one or more treatment paths, each treatment path defining a respective trajectory of spatial points, and each spatial point associated with a set of values for treatment axes of the external-beam radiation treatment system, wherein the one or more treatment paths correspond to an MLC angle defining a direction of MLC leaf motion;
• obtaining, by the computer system, beam's-eye view (BEV) projections of the first target volume and the second target volume along the one or more treatment paths based on the information about a first target volume and a second target volume;
• analyzing, by the computer system, the BEV projections of the first target volume and the second target volume to determine one or more contiguous ranges of spatial points along the one or more treatment paths where there exists an interstitial region subtended between the first target volume and the second target volume in the direction of MLC leaf motion;
• determining, by the computer system, a first set of MLC leaf sequences for the one or more treatment paths such that an aperture formed by the MLC in a first portion of the one or more contiguous ranges of spatial points exposes radiation to the first target volume but not the second target volume, and an aperture formed by the MLC in a second portion of the one or more contiguous ranges of spatial points exposes radiation to the second target volume but not the first target volume;
• and
• delivering, by the treatment head of the radiation treatment device, radiation to the patient according to the one or more treatment paths of the radiation treatment plan using the first set of MLC leaf sequences.

A computer product comprising a non-transitory computer readable medium storing a plurality of instructions that when executed control a computer system to determine MLC leaf sequences in a radiation treatment plan for treating a plurality of target volumes within a treatment area of a patient using an external-beam radiation treatment system, the instructions comprising:

• receiving, by the computer system, information about a first target volume and a second target volume of the plurality of target volumes;
• receiving, by the computer system, the radiation treatment plan including one or more treatment paths, each treatment path defining a respective trajectory of spatial points, and each spatial point associated with a set of values for treatment axes of the external-beam radiation treatment system, wherein the one or more treatment paths correspond to an MLC angle defining a direction of MLC leaf motion;
• obtaining, by the computer system, beam's-eye view (BEV) projections of the first target volume and the second target volume along the one or more treatment paths based on the information about a first target volume and a second target volume;
• analyzing, by the computer system, the BEV projections of the first target volume and the second target volume to determine one or more contiguous ranges of spatial points along the one or more treatment paths where there exists an interstitial region subtended between the first target volume and the second target volume in the direction of MLC leaf motion;
• and
• determining, by the computer system, a first set of MLC leaf sequences for the one or more treatment paths such that an aperture formed by the MLC in a first portion of the one or more contiguous ranges of spatial points exposes radiation to the first target volume but not the second target volume, and an aperture formed by the MLC in a second portion of the one or more contiguous ranges of spatial points exposes radiation to the second target volume but not the first target volume.