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Kilovoltage X-Ray Source in Medical Linac for Beam's Eye View Imaging

IP.com Disclosure Number: IPCOM000028018D
Publication Date: 2004-Apr-19
Document File: 4 page(s) / 32K

Publishing Venue

The IP.com Prior Art Database

Related People

Zirao Zheng: INVENTOR [+2]

Abstract

A kilovoltage x-ray source in the head of a linac is proposed. The kV source can move into a position to produce a collinear (with respect to the megavoltage treatment beam) beam for imaging. The focal spot of the kV source can be made to coincide with that of the MV treatment beam, providing true beam's eye view. It brings distinctive kV imaging capability to the linac, permitting high quality kilovoltage portal images and kV cone beam CT operation in the linac. The invention will benefit patient positioning and image-guided radiotherapy (IGRT).

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Our Docket No.: 2004J05381 Title: KILOVOLTAGE X-RAY SOURCE IN MEDICAL LINAC FOR BEAM'S EYE VIEW IMAGING Inventor(s): Zirao Zheng and Michelle Svatos

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Kilovoltage X-Ray Source in Medical Linac for Beam's Eye View Imaging

Abstract

A kilovoltage x-ray source in the head of a linac is proposed. The kV source can move into a position to produce a collinear (with respect to the megavoltage treatment beam) beam for imaging. The focal spot of the kV source can be made to coincide with that of the MV treatment beam, providing true beam's eye view. It brings distinctive kV imaging capability to the linac, permitting high quality kilovoltage portal images and kV cone beam CT operation in the linac. The invention will benefit patient positioning and image-guided radiotherapy (IGRT).

Background Information

The invention allows the linac to have kV imaging function and operation. It permits imaging along the main beam axis, i.e., the kV beam is collinear with the megavoltage treatment beam. A (MV) beam's eye view can be easily and routinely obtained.

The invention proposes to use a special x-ray tube to achieve a small form factor while delivering sufficient power for the intended imaging tasks. The kV source stays out of the way of the MV beam during treatment. In an imaging mode, it quickly moves into the position where its focal spot lies on the MV beam's axis. The focal spot can even be made to coincide with that of the MV beam, permitting a true beam's eye view.

Prior to this invention, kV imaging (prior or during MV radiotherapy) for patient positioning and IGRT has been achieve by a number of methods, including, 1) CT on rail system (e.g., University of North Carolina), 2) cross-beam kV source (kV beam perpendicular to MV beam, e.g., Elekta's Synergy and Varian's Trilogy), and 3) anti parallel kV beam (kV beam goes in the opposite direction of the MV beam, an imager attached to the accessory tray, e.g., DKFZ). These arrangements are cumbersome to use and occupy more space. Most of all, none of them provides a beam's eye view. This invention overcomes these shortcomings and enables a linac to have unparalleled kV imaging functionality.

Details

Figure 1 illustrates the basic idea of this invention. Several aspects of implementation are discussed in the following.

Mechanical The kV source takes a volume of approximately 8 cm x 8 cm x 20 cm. Length (2Ocm) is in the cross- plane. The x-ray tube slides on a plane perpendicular to the MV beam. It stays out of the MV beam during radiotherapy operations. It slides into the beam path in an imaging mode, emitting kV x-rays in the same direction as the MV beam. This provides collinear kV imaging.

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The location of the MV beam's focal spot and kV beam's focal spot can be designed to coincide to allow a true beam's eye view.

The tube features a fixed anode, which can take much small space than a rotating anode. Using direct cooling, it does not need an oil jacket. In addition, it...