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Saddle Coil Magnet for Radiotherapy MR

IP.com Disclosure Number: IPCOM000205250D
Original Publication Date: 2011-Mar-22
Included in the Prior Art Database: 2011-Mar-22
Document File: 2 page(s) / 316K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

In radiation therapy, high energy quanta are used to damage and ultimately destroy cancerous tissue in the human body. Breast, brain, abdomen, lung, and prostate tumors are main targets. Due to organ motion, in many anatomical regions it is desirable to combine radiotherapy with an imaging modality. This allows tracking the tumor position on-line, ensuring optimum results. One such combination is a LINAC (Linear Accelerator) and a magnetic resonance (MR) system. Numerous arrangements have been proposed. An existing first approach has the MR system’s main magnetic field orthogonal to the LINAC’s axis. It is then necessary to minimize the stray fields of the magnet at the LINAC by placing the LINAC at a distance, shielding, and/or modifying the MR main magnet’s field. The problem with this approach is that the LINAC is placed at some distance and the shielding may unduly affect the MR system’s magnetic field. The advantage of the approach is that both the magnetic resonance system and the LINAC are arranged close to the standard configurations of such modalities: An MR solenoidal magnet “tunnel” with its main magnetic field in the head-to-toe direction and with the radiation incident along an axis orthogonal to the head-to-toe direction.

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Saddle Coil Magnet for Radiotherapy MR

Idea: Dr. Patrick Gross, DE-Erlangen; Dr. Björn Heismann, DE-Erlangen

In radiation therapy, high energy quanta are used to damage and ultimately destroy cancerous tissue in the human body. Breast, brain, abdomen, lung, and prostate tumors are main targets. Due to organ motion, in many anatomical regions it is desirable to combine radiotherapy with an imaging modality. This allows tracking the tumor position on-line, ensuring optimum results. One such combination is a LINAC (Linear Accelerator) and a magnetic resonance (MR) system.

Numerous arrangements have been proposed. An existing first approach has the MR system's main magnetic field orthogonal to the LINAC's axis. It is then necessary to minimize the stray fields of the magnet at the LINAC by placing the LINAC at a distance, shielding, and/or modifying the MR main magnet's field. The problem with this approach is that the LINAC is placed at some distance and the shielding may unduly affect the MR system's magnetic field. The advantage of the approach is that both the magnetic resonance system and the LINAC are arranged close to the standard configurations of such modalities: An MR solenoidal magnet "tunnel" with its main magnetic field in the head-to-toe direction and with the radiation incident along an axis orthogonal to the head-to-toe direction.

A second approach produces the electrons in a LINAC aligned with the magnet's main magnetic field, but then re-directs the radiation using additional magnets. Again, a standard configuration of a solenoidal tunnel may be used. However, it is difficult to ensure that the LINAC's axis is not perturbed by the external field of the MR magnet, the use of additional magnets can disrupt the MR field homogeneity, and overall the complexity is increased.

A further approach uses a "C" shaped magnet and rotates this around the patient with the LINAC. This maintains the LINAC on the main symmetry axis of the magnet, ensuring that there a...