Method and apparatus for using a multi-layer multi-leaf collimation system

An apparatus for radiation modulation in radiation therapy, the apparatus comprising:

• a first multi-leaf collimator layer that is disposed proximal to a radiation source and that comprises a part of a discrete multi-leaf collimator, the first multi-leaf collimator layer being configured to primarily perform a first function as regards affecting a radiation beam traveling from the radiation source to a target and wherein leaves of the first multi-leaf collimator layer are constrained to a first maximum speed;
• a second multi-leaf collimator layer that is positioned distal to the radiation source and that also comprises an integral part of the discrete multi-leaf collimator, the second multi-leaf collimator layer being configured to primarily perform a second function as regards affecting the radiation beam that is different from the first function, and wherein leaves of the second multi-leaf collimator layer are constrained to a second maximum speed that is higher than the first maximum speed;
• and
• a control circuit configured to optimize a radiation treatment plan that utilizes both of the first and second multi-leaf collimator layers wherein the leaves in each of the first and second multi-leaf collimator layers are optimized according to each layer's specific maximum speed constraint for layer-specific functions, such that motions of each layer are optimized for the radiation treatment plan based on their individual maximum speed capability.