| 摘要 |
A radiotherapy apparatus collimator structure for limiting the lateral extent of a beam of radiation comprises a first multi-leaf collimator comprising a plurality of adjacent elongate leaves 60 controllably extendable into the beam in a first direction transverse to the radiation beam, and a block collimator 52,54 having at least one aperture 70a-f and controllably extendable into the beam in a second direction transverse to the first direction and the radiation beam for alignment with the beam to pass through. The aperture 70 is preferably cone-shaped and may be a through-hole, empty or filled with a radiotransparent material. There can be several apertures of varying dimensions incorporated into the block collimator 52,54, enabling placement of several stereotactic cones into the beam close to the patient. Apertures that are not needed can be covered by leaves 60 of the multi-leaf collimator. |
