Varian Medical Systems, Inc.

Varian Medical Systems International Ag

HsinLu Hsu

Magdalena Constantin

Janne Iimari Nord

Ross Bernald Hannibal

Steven W Prince

Stuart Scollay

Robert Kopels

Jonathan Evans

A phantom setup and source-to-surface distance (SSD) verification method uses radiation images. In an exemplary method, a phantom is positioned on a support relative to a radiation source such that a surface of the phantom is horizontally leveled at or approximate to a desired value of SSD. The radiation source is then positioned at a gantry angle predetermined at least based on the desired value of SSD such that a ray of radiation from the radiation source aligns with a horizontal surface located at the desired value of SSD. An image is acquired using radiation from the radiation source at the predetermined gantry angle. Verification is performed to confirm, based on an analysis of the image, if the surface of the phantom is positioned at the desired value of SSD.

Phantom setup and source-to-surface distance verification using radiation imaging

A multi level multileaf collimator employs leaves with leaf tips having a non-square shape in a beam's eye view to improve beam shaping effect and penumbra performance. The multi level multileaf collimator includes a first multileaf collimator in a first level comprising beam blocking leaves longitudinally movable in a first direction, and a second multileaf collimator in a second level comprising beam blocking leaves longitudinally movable in a second direction. The first direction may be generally parallel with the second direction and the leaves of the first multileaf collimator may laterally offset the leaves of the second multileaf collimator. The beam blocking leaves of the first multileaf collimator may comprise an end portion having a non-square shape in a beam's eye view.

Multi level multileaf collimator leaf tip shape effects and penumbra optimization

In a method of constructing a head shield for a radiation machine, the angular distribution of radiation propagating from a source and the angular function of thickness of a material in attenuating the radiation to a certain level of its original value are determined. Based on the angular distribution of radiation from the source and the angular function of thickness of the material, the thicknesses of the material at a plurality of angular locations around the source and distances from the source can be calculated for attenuating the radiation to or less than a predetermined threshold value. A shield around the source is constructed based on the calculated thicknesses of the material through iterative steps to ensure a cost-saving, weight-efficient, optimal solution. A method of designing a local radiation shield for a point of interest in a radiation system is also described to improve the machine reliability, regardless of the motion component of the POI with respect to the main radiation source and the secondary radiation source created by the patient scatter.

Radiation shields for LINAC head and system

Radiation shields for linac head and system

A multileaf collimator assembly employs one or more static blocks to significantly reduce extra focal leakage or out of field dose. The multileaf collimator assembly includes a plurality of pairs of beam shaping leaves. The leaves of each pair are movable relative to each other in a longitudinal direction. The one or more static blocks are disposed adjacent to the outermost pair of beam shaping leaves and unmovable in the longitudinal direction. The material composition and geometric characteristics of the static blocks may be chosen based on the pre-determined leakage specification for a particular radiation apparatus in the patient plane.

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Sunnyvale, CA, United States of America

HsinLu Hsu