Apparatus and method pertaining to dynamic use of a radiation therapy collimator

An apparatus for use in administering radiation therapy to a target volume of a patient using a radiation-therapy beam and differing angles of exposure in conjunction with a multileaf collimator, comprising:

• a first memory having treatment-plan information regarding a plurality of different angles of exposure to employ when administering the radiation therapy to the target volume stored therein;
• a processor operably coupled to the first memory and being configured to use the treatment-plan information to determine corresponding, and differing, aperture configurations for a second collimator that is disposed between a source for the radiation-therapy beam and the multileaf collimator and that is to be dynamically used when administering the radiation therapy for at least some of the differing angles of exposure.

An apparatus for use in administering radiation therapy to a target volume of a patient using a radiation-therapy beam and differing angles of exposure in conjunction with a multileaf collimator and a second collimator that is disposed between a source for the radiation-therapy beam and the multileaf collimator, comprising:

• a first memory having treatment-plan information regarding a plurality of different angles of exposure to employ when administering the radiation therapy to the target volume stored therein;
• a processor operably coupled to the first memory and being configured to use the treatment-plan information to dynamically vary aperture configurations for the second collimator when administering the radiation therapy for at least some of the differing angles of exposure.