Varian Associates, Inc.

Varian Medical Systems, Inc.

Calvin J Huntzinger

David Kirk Jensen

William A Strachan

A beam filter positioning device includes a first and a second axes operable to move a body supporting one or more collimators, one or more photon flattening filters, one or more electron foils, and field light mirror etc. The collimators may be configured to collimate radiation to define a treatment beam suitable for radiosurgery. A controller is programmed to control the servo motor of the first and second axes to accurately position the beam filters. Radiation apparatuses and systems incorporating the beam filter positioning device or assembly are also provided.

Internally mounted collimators for stereotactic radiosurgery and stereotactic radiotherapy

A multileaf collimator for use in therapeutic radiology treatment systems for producing irregular shaped radiation fields in order to shield normal tissue or critical organs. A multileaf collimator following the present invention includes leaves designed such that the collimator exhibits penumbra which is minimized and generally uniform for positions that are equidistant from the central axis of the radiation field. The shape of each leaf end includes an asymmetric central portion and a flat portion on either side of the central portion. The central portion is designed such that geometric penumbra and transmission penumbra are equalized. The flat portions on either side of the central portion are coincident with a tangent drawn from the edge of the radiation source to a reference plane when the leaf is in the fully retracted or fully extended positions.

Leaf-end configuration for multileaf collimator

A microwave electron accelerator has a very limited range over which pulse beam current can be adjusted without destabilizing the operation of the machine. Therefore, means must be devised to reduce current without seriously reducing energy, or producing unwanted x-rays. One means includes spreading the beam in a scattering foil and subsequently absorbing the outer portion with a blocking wall. In order to make the means adjustable the foil thickness, the size of a passing aperture in the blocking wall or the position of the blocking wall can be adjusted.

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San Carlos, CA, United States of America

Calvin J Huntzinger