Integrated variable-aperture collimator and fixed-aperture collimator

#This invention relates to the field of radiation treatment and in particular, an apparatus and a method for coupling a fixed-aperture collimator to a variable-aperture collimator in a radiation treatment system.

#Some of the clinical requirements of designing a radiosurgical treatment system include providing: a) a highly precise beam delivery to targets located throughout the body, b) a highly conformal dose distribution, c) the ability to irradiate both small and/or large complex-shaped lesions. To do this, the system uses a combination of beam positions whose relative beam weights, or dose contributions, have been scaled to volumetrically shape the dose accordingly. One or more collimators can be selected to give the beams the required shape to achieve the desired clinical result. Collimators are used in linear accelerators (LINACs) of radiation treatment systems, such as radiosurgery or radiotherapy systems. The collimators help to shape the beam of radiation emerging from the LINAC, and they can limit the maximum field size of the beam. The treatment head of the LINAC typically includes both a primary collimator and a secondary collimator.

#Current radiation treatment surgery system such as the CYBERKNIFE® radiosurgery system, manufactured by Accuray™ Incorporated, USA, relies on a set of twelve circular, fixed-aperture secondary collimators to reduce the beam to the size required by the treatment planning algorithm. Because the apertures of these secondary collimators are of fixed-size, one fixed-aperture collimator individually does not provide flexibility of having an aperture of different sizes. The set of fixed-aperture secondary collimators are used to provide this flexibility; however, when a different size of aperture is to be used in the radiation treatment system, the fixed-aperture collimator needs to be changed. Currently changing of these collimators is accomplished manually by hand.

#The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

#FIG. 1 illustrates a manual process of changing a fixed-aperture collimator.

#FIG. 2 illustrates a fixed-aperture collimator released from a collimator housing during a manual process of changing a collimator.

#Described herein are a method and an apparatus for coupling a fixed-aperture collimator to a variable-aperture collimator. The following description sets forth numerous specific details such as examples of specific systems, components, methods, and so forth, in order to provide a good understanding of several embodiments of the present invention. It will be apparent to one skilled in the art, however, that at least some embodiments of the present invention may be practiced without these specific details. In other instances, well-known components or methods are not described in detail or are presented in simple block diagram format in order to avoid unnecessarily obscuring the present invention. Thus, the specific details set forth are merely exemplary. Particular implementations may vary from these exemplary details and still be contemplated to be within the spirit and scope of the present invention.

#As described in greater detail below, the embodiments described herein include an integrated collimator for use in radiation treatment system. The integrated collimator may include a variable-aperture collimator and a fixed-aperture collimator coupled to the variable-aperture collimator. At least a portion of the outer-diameter surface of the fixed-aperture collimator is coupled to the inner-diameter surface of the variable-aperture collimator. The variable-aperture collimator may be a secondary collimator coupled to the end of the primary collimator at which the radiation beam exits the primary collimator. The LINAC may be a robot-based or a gantry-based LINAC. The robot-based LINAC may be coupled to a robot arm.

#The variable-aperture collimator may be an IRIS collimator having multiple leaves configured to open and close an aperture of the IRIS collimator. In one embodiment, the IRIS collimator may be an IRIS collimator developed by Deutsche Krebsforschungszentrum (DKFZ), Hiedelberg, Germany. Alternatively, the IRIS collimator may be other types of IRIS collimators. The IRIS collimator may be a six-sided IRIS collimator having six leaves to open and close the aperture of the IRIS collimator. Alternatively, other numbers of leaves may be used in the IRIS collimator.