Volumetric modulated arc therapy (vmat) with non-coplanar trajectories

A radiation treatment system, comprising:

• a candidate beam direction determiner configured to determine a set of candidate beam directions;
• a beam direction selector configured to select a sub-set of non-coplanar beam directions from the set of candidate beam directions based on a fluence optimization using a beam angle selection algorithm;
• a beam trajectory determiner configured to determine a set of delivery options that at least include a delivery that involves both beam rotation and subject support rotation during volumetric arc delivery;
• and
• a plan optimizer configured to optimize the delivery options, which generates a VMAT radiation plan with non-coplanar beam directions
• wherein the fluence optimization is based on:
• minimize F(d), where d represents a dose distribution and F is objective function quantifying deviation of the dose distribution d from treatment goals, wherein the dose distribution d is determined by:
• d=Σb∈C⊂BDbxb, where B represents the set of candidate beam directions, C represents the sub-set, b represents a beam index, xb represents a vector of beamlet intensities for the beam b, and Db represents a corresponding dose-fluence matrix,
• wherein the beam direction selector approximates minimize F(d) by performing a predetermined first number of iterations of a gradient descent algorithm, wherein the objective function value reached after the predetermined first number of iterations represents a score for a quality of a candidate beam, or
• wherein the beam direction selector selects the beams angle based on a norm of a gradient of the objective function in an iteration to obtain a beam score, add the beam to the beam ensemble Cn, fix the fluence maps of all beams the beam ensemble Cn at their optimal values while a new candidate beam b has zero fluence.

A non-transitory computer readable medium encoded with computer executable instructions, which when executed by a processor, causes the processor to:

• determine a set of candidate beam directions;
• select a sub-set of non-coplanar beams from the set of candidate beam directions based on a fluence optimization using a beam angle selection algorithm;
• determine a set of delivery options based on a beam trajectory algorithm, wherein the delivery options at least include:
• a delivery that involves both beam rotation and a subject support rotations during volumetric arc delivery;
• optimize the delivery options, which generates a VMAT radiation plan with non-coplanar beam directions;
• and
• control a radiation treatment system in VMAT mode to continuously deliver radiation based on non-coplanar trajectories while rotating the beam and rotating the subject support based on the signal,
• wherein the fluence optimization is based on:
• minimize F(d), where d represents a dose distribution and F is an objective function quantifying deviation of the dose distribution d from treatment goals, wherein the dose distribution d is determined by:
• d=Σb∈C⊂BDbxb, where B represents the set of candidate beam directions, C represents the sub-set, b represents a beam index, xb represents a vector of beamlet intensities for the beam b, and Db represents a corresponding dose-fluence matrix,
• wherein minimize F(d) is approximated by performing a predetermined first number of iterations of a gradient descent algorithm, wherein the objective function value reached after the predetermined first number of iterations represents a score for a quality of a candidate beam, or
• wherein the beam angle is selected based on a norm of a gradient of the objective function in an iteration to obtain a beam score, the beam is added to the beam ensemble Cn, the fluence maps of all beams of the beam ensemble Cn are fixed at their optimal values while a new candidate beam b has zero fluence.