Method and apparatus to employ a multi-layer multi-leaf collimator when administering a radiation therapy treatment

An apparatus comprising:

• a source of therapeutic radiation configured to emit a radiation beam;
• a multi-layer multi-leaf collimation system wherein a proximal layer of a plurality of collimation leaf pairs are vertically offset with respect to a distal layer of a plurality of collimation leaf pairs such that the two multi-layer multi-leaf collimators combine to form a plurality of linearly-sequential high-resolution aperture possibilities;
• and
• a control circuit operably coupled to the source of therapeutic radiation and to the multi-layer multi-leaf collimation system, the control circuit being configured to administer a radiation treatment plan that specifies a planned total radiation dose for a radiation treatment session for a given patient, at least in part and for a first treatment field, by administering two and only two radiation exposures, wherein:
• a first radiation exposure for the first treatment field comprises modulating a radiation beam using a first fixed aperture that includes at least one high-resolution aperture that is formed using one of the plurality of linearly-sequential high-resolution aperture possibilities;
• and
• a second separate radiation exposure for the first treatment field comprises modulating the radiation beam using a second fixed aperture that is different from the first fixed aperture and that includes at least one high-resolution aperture that is formed using one of the plurality of linearly-sequential high-resolution aperture possibilities.

A method for use with a radiation therapy treatment platform having a multi-layer multi-leaf collimation system wherein a proximal layer of a plurality of collimation leaf pairs are vertically offset with respect to a distal layer of a plurality of collimation leaf pairs such that the two multi-layer multi-leaf collimators combine to form a plurality of linearly-sequential high-resolution aperture possibilities, the method comprising:

• by a control circuit:
• administering a radiation treatment plan that specifies a planned total radiation dose for a radiation treatment session for a given patient by, at least in part and for a first treatment field, administering two radiation exposures, wherein:
• a first radiation exposure for the first treatment field comprises modulating a radiation beam using a first fixed aperture that includes at least one high-resolution aperture that is formed using one of the plurality of linearly-sequential high-resolution aperture possibilities;
• and
• a second separate radiation exposure for the first treatment field comprises modulating the radiation beam using a second fixed aperture that is different from the first fixed aperture and that includes at least one high-resolution aperture that is formed using one of the plurality of linearly-sequential high-resolution aperture possibilities.