MAGNETIC RESONANCE IMAGING RECEIVE COIL WITH REDUCED RADIATION ATTENUATION

Abstract

The invention provides for magnetic resonance antenna (100), wherein the magnetic resonance antenna is a surface coil and is a receive coil. The magnetic resonance antenna comprises one or more antenna elements (104, 404). The magnetic resonance antenna further comprises a preamplifier (402) for the antenna element and a coil former (106) for supporting the antenna element. The coil former is formed from a porous material. The antenna is divided into an irradiation zone (204) and at least one reduced radiation zone (202, 206). The preamplifier for each of multiple antenna elements is located within the at least one reduced radiation zone. The multiple antenna elements are located at least partially within the irradiation zone. The coil former has a perimeter, wherein the irradiation zone extends continuously from a first edge (208) of the perimeter to a second edge (210) of the perimeter. The first edge and the second edge are opposing edges.

Claims

1-15. (canceled)

16. A medical instrument comprising: a LINAC with an X-ray source for directing X-ray radiation at a target zone, wherein the LINAC is adapted for rotating the X-ray source about a rotational axis; and a magnetic resonance imaging system for acquiring magnetic resonance data with a magnetic resonance antenna from an imaging zone, wherein the target zone is within the imaging zone, wherein the magnetic resonance imaging system comprises a magnet for generating a magnetic field within the imaging zone, wherein the X-ray radiation source is adapted for rotating at least partially about the magnet; wherein the magnetic resonance imaging system comprises a magnetic resonance antenna, wherein the magnetic resonance antenna is a surface coil, wherein the magnetic resonance antenna is a receive coil, wherein the magnetic resonance antenna comprises: an antenna element a preamplifier for the antenna element; and a coil former for supporting the antenna element, wherein the coil former is formed from a porous material, wherein the coil former is rigid, wherein the coil former is divided into an irradiation zone and at least one reduced radiation zone, wherein the preamplifier for the antenna element is located within the at least one reduced radiation zone, wherein the antenna element is located at least partially within the irradiation zone, wherein the coil former has a perimeter, wherein the irradiation zone extends continuously from a first edge of the perimeter to a second edge of the perimeter, and wherein the first edge and the second edge are opposing edges.

17. The medical instrument of claim 16, wherein the porous material is any one of the following: a foam, expanded polypropylene, Polyurethane foam, Polyimide foam, PEEK foam, a corrugated structure, corrugated cardboard, and a honeycomb structure and/or has an attenuation of less than 2 percent for X-ray radiation between 1.8 MeV and 8 MeV.

18. The medical instrument of claim 16, wherein a cross section of the coil former from the first edge to the second edge is predominantly convex when observed from a direction from the coil former to the antenna element.

19. The medical instrument of claim 18, wherein the cross section is any one of the following: a semi-circle, comprising straight segments and rounded segments, generally flat with rounded portions near the first edge and the second edge, and a series of connected straight segments.

20. The medical instrument of claim 16, wherein the coil former comprises one or more mounting fixtures for attaching the magnetic resonance antenna to a subject support.

21. The medical instrument of claim 16, wherein the antenna element is formed on a flexible printed circuit board, wherein the flexible printed circuit is attached to the coil former.

22. The magnetic resonance antenna of claim 16, comprising multiple antenna elements, wherein the at least one reduced radiation zone is two or more reduced radiation zones, wherein the two or more reduced radiation zones comprise PIN diodes for controlling detuning of the multiple antenna elements, wherein the irradiation zone comprises conductors for carrying electrical signals between the two or more reduced radiation zones for controlling the switching of the PIN diodes.

23. The magnetic resonance antenna of claim 16, wherein the magnetic resonance antenna has a first surface and a second surface, wherein the coil former is between the first surface and the antenna element, wherein the antenna element is between the second surface and the coil former, wherein the magnetic resonance antenna further comprises: a biocompatible layer that forms the first surface and an outer layer that forms the second surface.

24. The magnetic resonance antenna of claim 23, wherein the first biocompatible layer is any one of the following: Ethylene-vinyl acetate, polyurethane, polyamide foam, PEEK foam, and PVC foam and/or the outer layer is any one of the following: Ethylene-vinyl acetate, PVC foam, and polyurethane, PEEK foam, and PVC foam.

25. The magnetic resonance antenna of claim 23, wherein the first biocompatible layer is laminated to the coil former and/or wherein the second biocompatible layer is laminated to the antenna element.

26. The magnetic resonance antenna of claim 16, wherein the thickness of the porous material is uniform.

27. The medical instrument of claim 26, wherein the medical instrument further comprises: a processor for controlling the medical instrument; a memory for storing machine executable instructions for execution by the processor, wherein execution of the machine executable instructions causes the processor to: receive a treatment plan for irradiating the target zone; acquire the magnetic resonance data using the magnetic resonance imaging system; reconstruct a magnetic resonance image from the magnetic resonance data; register a location of the target zone in the magnetic resonance image; generate control signals in accordance with the location of the target zone and the treatment plan; and control the LINAC to irradiate the target zone using the control signals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In the following preferred embodiments of the invention will be described, by way of example only, and with reference to the drawings in which:

[0056] FIG. 1 shows an exploded view of an example of a magnetic resonance antenna;

[0057] FIG. 2 shows the magnetic resonance antenna of FIG. 1 in assembled form;

[0058] FIG. 3 shows a cross sectional view of a further example of a magnetic resonance antenna;

[0059] FIG. 4 shows a top view of a further example of a magnetic resonance antenna;

[0060] FIG. 5 shows a cross sectional view of a further example of a magnetic resonance antenna;

[0061] FIG. 6 shows a cross sectional view of a further example of a magnetic resonance antenna;

[0062] FIG. 7 shows a cross sectional view of a further example of a magnetic resonance antenna;

[0063] FIG. 8 shows a cross sectional view of a further example of a magnetic resonance antenna;

[0064] FIG. 9 shows a cross sectional view of a further example of a magnetic resonance antenna;

[0065] FIG. 10 shows a cross sectional view of a further example of a magnetic resonance antenna;

[0066] FIG. 11 illustrates a possible stack of materials which may be used to form the structure of a flexible printed circuit board suitable for a magnetic resonance antenna;

[0067] FIG. 12 shows an example of an antenna element with a detune circuits;

[0068] FIG. 13 shows a further example of an antenna element with a detune circuit;

[0069] FIG. 14 shows an example of the spatial distribution of radiation from a radiation beam;

[0070] FIG. 15 shows an embodiment of a medical apparatus; and

[0071] FIG. 16 shows a flowchart which illustrates a method of operating the medical apparatus of FIG. 15.

DETAILED DESCRIPTION

[0072] Like numbered elements in these figures are either equivalent elements or perform the same function. Elements which have been discussed previously will not necessarily be discussed in later figures if the function is equivalent.

[0073] In some examples of a combined magnetic resonance (MR) imaging system and a LINAC, the receive coils or antenna of the MR LINAC system are placed as close as possible to the treated and imaged anatomy to maximize image quality and enable MR LINAC system to provide efficient MR guidance for the radiation beam. As a consequence, receive coils are located in the radiation beam path and this results that the coils attenuate and may cause non-idealities in the radiation therapy which may need to be taken into account in the delivery of the treatment. The receive coils are also exposed to relatively high radiation dose, that may affect the properties of the materials and electronics decreasing the overall lifetime of the coils.

[0074] A coil that minimally disturbs the radiation beam and the operation of which is minimally affected by the irradiation is crucial in the MR Linac application.

[0075] Examples may have an irradiation zone that enables radiation to pass through the coil minimally disturbing the dose delivery to the target or to other organs. The attenuation of the irradiation zone can be such that the attenuation can be neglected in the treatment planning This streamlines user workflow and thus enables faster treatment planning and dose delivery.

[0076] The irradiation zone of the coil increases the reliability of the coil in the high dose environment. The sensitive electronics and materials are not located within the zone, which minimizes the amount of accumulated dose in the sensitive parts over the lifetime of the coil.

[0077] In some examples the irradiation zone within a receive coil can have one or more of the following elements: [0078] An area within the coil that is free of discrete electronic components [0079] An area that has minimized attenuation been made of low density materials, the structure construction can be rigid [0080] An area that has electrical conductors that minimally disturb the radiation beam [0081] A coil where the effect of radiation on the electronics is minimized by the placement and/or shielding.

[0082] FIG. 1 shows an example of a magnetic resonance antenna 100. In the antenna 100 is a composite made out of a variety of layers. In FIG. 1 these layers are shown in an expanded view. There is an outer layer 102 that is in contact with a flexible printed circuit board 104. The flexible printed circuit board 104 contains the one or multiple antenna elements. The flexible printed circuit board 104 is then connected to a coil former 106. The coil former 106 in this example is a rigid foam or porous material. The coil former 106 is then connected to a biocompatible layer 108 that may be in contact with a subject. These four layers may be glued or laminated together to form a rigid magnetic resonance antenna.

[0083] FIG. 2 shows the antenna 100 after it has been laminated together. The coil 100 is a surface coil that is a bit curved. On one side there is a first reduced radiation zone 202. In the middle of the coil 100 there is a irradiation zone 204. And on the other end there is a second reduced radiation zone 206. In the irradiation zone 204 there are no electronic components electronic components have been moved to the first reduced radiation zone 202 and the second reduced radiation zone 206. There is a perimeter about this antenna 100. It can be seen there is a first edge 208 and a second edge 210 that are on opposite sides of the antenna 100. A cross-section or line can be drawn from the first edge 208 to the second edge 210 that stays within the irradiation zone 204. The antenna shown in FIGS. 1 and 2 may be used in a LINAC system. The possible area where the beam may travel is aligned with the irradiation zone 204 and the electronics in the first 202 and second 206 reduced radiation zones are kept out of the X-ray beam path.

[0084] The irradiation zone of the structure is where the materials mentioned above create maximally homogenous area within the coil, i.e. may have no cutouts or other materials or components in it. This irradiation zone can be in the middle of the coil, or in one end of the coil. In case the irradiation zone is in one end of the coil, the coil can be used in combination with other similar coil. The irradiation zone placements within the coil are shown in FIGS. 8, 9, and 10. The irradiation zone placed on the beam path has a length of greater than the radiation beam itself.

[0085] The magnetic resonance receive coil may have the feature of a mechanical structure of low density materials or foam that may be rigid. The structure can be made of various alternative materials in a form sandwich that enhances the rigidity of the structure, as shown in FIG. 1.

[0086] The core of the structure is made of rigid, low density foam or material e.g. EPP (Expanded polypropylene). The material can be either machined or molded to its form. This part forms the basis for the structure in terms of rigidity. The density of the material is low, ˜100 kg/m3.

[0087] The outer surface of the structure is made of low density soft foam or material e.g. EVA (Ethylene-vinyl acetate). This foam or material is providing the biocompatible surface for the structure. Due to its closed cell structure, it also prevents liquids to ingress the structure. The material density is ˜50 kg/m3.

[0088] In between the foam or material layers, the coil winding printed circuit board (PCB) is assembled. The foam or low density materials mentioned above and the PCB in between are thermo molded together to form the final structure and shape of the product. A thin layer of glue is attached between each layer to keep the layers firmly attached.

[0089] FIG. 3 shows a cross-sectional view 300 of a magnetic resonance antenna 100. In this case the cross-section 300 is a semi circle. The first edge 208 and the second edge 210 could be placed on a centric support and the subject could be placed in the semi circle. From within the semi circle 300 the cross-section is concave 302. A upview is shown in FIG. 4. The line marked 400 shows the location of the cross-section 300 shown in FIG. 3. The first reduced radiation zone 202 and the second reduced radiation zone 206 are also shown. In between the first 202 and the second 206 reduced radiation zone is the irradiation zone 204. There are four copper strip antenna elements 404. Within the first reduced radiation zone 202 there are a number of pre-amplifiers and other electronics 402. The copper strips 404 are connected to the pre-amplifiers 402. The copper strip antennas 404 are very long and run the entire length of the antenna 100.

[0090] To make it easier to detune the elements 404 when the antenna is not in the receive mode there is a number of PIN diodes 406 and/or other electronics located in the second reduced radiation zone 206. These PIN diodes 406 are controlled by electronics in the pre-amplifier 402. There is a flat copper conductors 408 which act as a control for the electronics 406. This enables the very long copper strip antenna elements 404 to be detuned. The flat copper conductors 408 are narrower than the copper strips 404. This means that their impedance at radio frequency are higher. This may enable the control PIN diode 406 without interference from radio frequency signals from a magnetic resonance imaging system.

[0091] FIG. 5 shows a cross-sectional view 500 which may be an alternative to that shown in FIG. 3. In this view the cross-sectional view is generally flat and rounded near the ends 208 and 210.

[0092] FIG. 6 shows a further alternative cross-section 600. The cross-section 600 may be used instead of the cross-section 300 shown in FIG. 3. In this cross-section there is a flat portion or straight with rounded edges near the ends 208 and 210. In FIG. 6 there is a mixture of straight segments and curved or rounded segments.

[0093] FIG. 7 shows an alternative cross-sectional view 700 it is an alternative to the cross-sectional view 300 shown in FIG. 3. In this cross-sectional view the cross-section is completely comprised of straight line segments.

[0094] It should be noted that in all cross-sectional views shown in FIG. 3, FIG. 5, FIG. 6, and FIG. 7 they are all concave 302 with respect to where the subject would be placed. It may be advantageous to have the antennas be concave in this fashion because as the LINAC rotates the X-ray radiation source about the subject it reduces the amount of antenna that the radiation must pass through. This reduces the amount of attenuation by the antenna 100.

[0095] In various example there may be one or there may be several reduced radiation zones. FIGS. 8, 9 and 10 show several different examples. The examples shown in FIGS. 8, 9 and 10 show straight cross-sections. However these straight cross-sections are only exemplary and the coils or antennas may be curved as is illustrated in FIGS. 3, 5, 6 and 7.

[0096] In FIG. 8 a cross-sectional view 800 of an antenna 100 is shown. The example is similar to that of the example shown in FIG. 1. There is an electrical connection 802 going to a reduced radiation zone 202. The irradiation zone 204 borders the reduced radiation zone 202. On the other side of the reduced irradiation zone 204 there is a second reduced radiation zone 206.

[0097] Another topology is shown in FIG. 9. In FIG. 9 a further cross-sectional view 900 of a magnetic resonance antenna 100 is shown. In this example there is an electrical connection 802 going to a first reduced radiation zone 202. The reduced radiation zone 202 is in contact with the irradiation zone 204.

[0098] FIG. 10 shows a further example of the antenna 100 the cross-sectional view 1000 is shown as having two complete sets of coils which border each other. There is an electrical connection 802 going to the first reduced radiation zone 202 and there is a second electrical connection 802 going to the second reduced radiation zone 206. The irradiation zone 204 is divided into two pieces which may have separate antenna elements.

[0099] Examples of magnetic resonace receive coils may also use Flex printed circuit board (PCB) for the coil elements is made of thin radiation hard PCB substrates and thin and narrow copper traces for electrical connections. An example build-up for the PCB structure is shown in FIG. 11. The PCB is made of thin layers of Polyimide, which has good radiation hardness.

[0100] FIG. 11 illustrates the stack of materials which may be used to form the structure 1100 of a flexible printed circuit board suitable for examples. There is a top layer which is formed of polyimide this is connected with an adhesive to a copper layer which is then connected to another polyimide layer another adhesive layer and then a final polyimide layer. The first polyimide layer as shown is being as 13 micrometers thick. This for example may be between five and 25 micrometers. The various adhesive layers may be thicker or thinner. The copper layer is shown as being 18 micrometers. Copper layer thicknesses which work well may for example be between 18 and 35 micrometers thick. The copper is attached to a 125 micrometer polyimide layer. This may be thicker or thinner. For example, this polyimide layer may be between for example 25 to 200 micrometers thick. The lower polyimide layer is shown as being 13 micrometers. This for instance may be between 5 and 25 micrometers thick.

[0101] The copper traces that carry RF electromagnetic waves and DC current, are optimized minimally to shadow and attenuate the radiation beam within the irradiation zone. In some examples there may different types of traces or conductors. For example: a) RF trace, purpose of which is to carry RF only; b) DC+RF trace, the purpose of which is to carry both DC and RF, and the DC trace is geometrically located on the left side of the RF trace; and c) RF+DC trace, the purpose of which is the same as in b) with exception that DC trace is right side oriented.

[0102] Examples of magnetic resonance receive coils may also have the feature of distributed discrete electronic modules within the coil loop outside the irradiation zone. This optimizes MR performance of the receive coil during the radiation. This may be achieved by distributing multiple detune circuits with high impedance (Z.sub.det) along the coil loop such way that total impedance during the transmit state of the system is high enough to prevent high transmit power to reduce coil performance. In FIGS. 12 and 13 this is shown the block diagram of two different loops with detune circuits and the irradiation zone.

[0103] FIG. 12 shows a detune circuit for an antenna element 404. In the example shown in FIG. 12 the irradiation zone 204 is between 2 202, 206 reduced radiation zones. Within the reduced irradiation zones 202 and 204 there are detune circuits 402, 406 that for example may be PIN diodes or other detune circuits.

[0104] FIG. 13 shows a further example of an antenna element 404 with its detuned circuits 402. In this example there is only one reduced radiation zone 202 which is adjacent to the irradiation zone 204.

[0105] High impedance points within the loop, with an area of A, minimize the current flowing in the loop when the loop is exposed to high RF transmit field of B1. The induced voltage u is

[00001]$\begin{array}{cc}\begin{array}{c}u=.Math.-\frac{d\left[B_1\left(t\right).Math.A\right]}{\mathrm{dt}}\\ =.Math.-\omega .Math..Math.{\mathrm{AB}}_1.Math..Math.\cos \left(\omega .Math..Math.t\right)\end{array}& \left(1\right)\end{array}$
.fwdarw.|U|=ωAB.sub.1max, where ω=2πf.   (2)

[0106] For a rectangular loop with width of a and length of b, the magnetic field in the center B.sub.c is

[00002]$\begin{array}{cc}{B}_c=\frac{2.Math.{\mu }_0.Math.I_{\mathrm{loop}}.Math.b}{\pi .Math..Math.a.Math.\sqrt{a^2+b^2}}+\frac{2.Math.{\mu }_0.Math.I_{\mathrm{loop}}.Math.a}{\pi .Math..Math.b.Math.\sqrt{a^2+b^2}}& \left(3\right)\end{array}$

[0107] Where I.sub.loop is the induced current in the loop

[00003]$\begin{array}{cc}{I}_{\mathrm{loop}}=\frac{.Math.U.Math.}{Z_{\det }^{\mathrm{total}}}& \left(4\right)\end{array}$

[0108] The performance of the coil is not reduced when B.sub.c≦0.1 B.sub.1 then we can require that:

[00004]$\begin{array}{cc}{Z}_{\det }^{\mathrm{total}}\ge \frac{20.Math.{\mu }_0.Math.\omega .Math..Math.\mathrm{Ab}}{\pi .Math..Math.a.Math.\sqrt{a^2+b^2}}+\frac{20.Math.{\mu }_0.Math.\omega .Math..Math.\mathrm{Aa}}{\pi .Math..Math.b.Math.\sqrt{a^2+b^2}},& \left(5\right)\end{array}$

which can be distributed over multiple detune points Z.sub.det.sup.total=n.sub.detZ.sub.det.

[0109] These detune points are distributed such a way that the irradiation zone length is maximized [0110] Distributing the coil preamplifiers away from the radiation beam path such a way that the accumulated dose is minimal to enable high image quality over the lifetime. The distance of the preamplifier to the beam iso center x is selected such a way that the dose due to the beam is in the order of 2% or lower at the location of preamplifier, see FIG. 14. [0111] Shielding the coil preamplifiers with materials with high radiation attenuation such way that the dose at the preamplifier is in the order of 2% of the maximum beam dose.

[0112] FIG. 14 shows an example of the spatial distribution of radiation from a radiation beam 1400. The nominal beam width is labeled 1402. The beam isocenter is labeled 1404. The region of considered to be 100% dose is labeled 1406 and the region labeled 2% dose is labeled 1408. The region above 2% dose is considered to be the irradiation zone 204 and the two regions with 2% and less dose in this example are considered to be the first 202 and second 206 reduced radiation zones.

[0113] FIG. 15 shows an example of a medical apparatus 1500 according to the invention. The medical apparatus 1500 comprises a LINAC 202 and a magnetic resonance imaging system 1504. The LINAC 1502 comprises a gantry 1506 and a X-ray source 1508. The gantry 1506 is for rotating the X-ray source 1508 about an axis of gantry rotation 1540. Adjacent to the X-ray source 1508 is an adjustable collimator 1510. The adjustable collimator 1510 may for instance have adjustable plates for adjusting the beam profile of the X-ray source 1508. The adjustable collimator may, for example, be a multi-leaf collimator. The magnetic resonance imaging system 1504 comprises a magnet 1512.

[0114] The magnet 1512 shown in FIG. 15 is only an example. It is also possible to use permanent or resistive magnets. The use of different types of magnets is also possible for instance it is also possible to use both a split cylindrical magnet and a so called open magnet.

[0115] A split cylindrical magnet is similar to a standard cylindrical magnet, except that the cryostat has been split into two sections to allow access to the iso-plane of the magnet, such magnets may for instance be used to provide a space to for X-ray radiation to reach a subject 1536. An open magnet has two magnet sections, one above the other with a space in-between that is large enough to receive a subject: the arrangement of the two sections area similar to that of a Helmholtz coil. Open magnets are popular, because the subject is less confined. Inside the cryostat of the cylindrical magnet there is a collection of superconducting coils.

[0116] The magnet 1512 shown in this example is a modified cylindrical superconducting magnet. The magnet 1512 has a cryostat 1514 with superconducting coils within it 1516. The magnet is designed such that a X-ray radiation beam 1542 does not intersect the superconducting coils 1516. The materials and thicknesses along the beam path 1542 may be chosen to reduce the attenuation of the X-ray radiation. As mentioned above a split or open magnet design may be used instead to eliminate the absorption of radiation by the magnet 1512.

[0117] The magnet 1512 has a bore 1522. Within the bore 1522 of the cylindrical magnet 1512 there is an imaging zone where the magnetic field is strong and uniform enough to perform magnetic resonance imaging.

[0118] Within the bore 1522 of the magnet 1512 is a magnetic field gradient coil 1524 for acquisition of magnetic resonance data to spatially encode magnetic spins within an imaging zone of the magnet. The magnetic field gradient coil 1524 is connected to a magnetic field gradient coil power supply 1526. The magnetic field gradient coil 1524 is intended to be representative, to allow radiation to pass through without being attenuated it will normally be a split-coil design. Typically magnetic field gradient coils contain three separate sets of coils for spatially encoding in three orthogonal spatial directions. The magnetic field gradient power supply 1526 supplies current to the magnetic field gradient coils. The current supplied to the magnetic field coils is controlled as a function of time and may be ramped or pulsed.

[0119] There is a radio frequency coil 1528 connected to a transceiver 1530. The radio frequency coil 1528 is adjacent to an imaging zone 1532 of the magnet 1512. The imaging zone 1532 has a region of high magnetic field and homogeneity which is sufficient for performing magnetic resonance imaging. The radio frequency coil 1528 may is for manipulating the orientations of magnetic spins within the imaging zone and possibly for receiving radio transmissions from spins also within the imaging zone. The radio frequency coil 1528 may also be referred to as an antenna or channel. The radio frequency coil 1528 may contain multiple coil elements. The radio frequency antenna may also be referred to as a channel.

[0120] The radio frequency coil 1528 and radio frequency transceiver 1530 may be replaced by separate transmit and receive coils and a separate transmitter and receiver. It is understood that the radio frequency coil and the radio frequency transceiver are simply representative. The radio frequency antenna is intended to also represent a dedicated transmit antenna and a dedicated receive antenna. Likewise the transceiver may also represent a separate transmitter and receivers.

[0121] Also within the bore of the magnet 1522 is a subject support 1534 for supporting a subject 1536. The subject support 1534 may be positioned by a mechanical positioning system 1537. Within the subject 1536 there is a target zone 1538. The axis of gantry rotation 1540 is coaxial in this particular example with the cylindrical axis of the magnet 1512. The subject support 1534 has been positioned such that the target zone 1538 lies on the axis 1540 of gantry rotation. The X-ray source 1508 is shown as generating a radiation beam 1542 which passes through the collimator 1510 and through the target zone 1538. As the radiation source 1508 is rotated about the axis 1540 the target zone 1538 will always be targeted by the radiation beam 1542. The radiation beam 1542 passes through the cryostat 1514 of the magnet. The magnetic field gradient coil 1524 has a gap 543 which separate the magnetic field gradient coil into two sections. The gap 1543 reduced attenuation of the radiation beam 1542 by the magnetic field gradient coil 1524. Alternatively a split magnetic field gradient coil may be used.

[0122] A receive magnetic resonance antenna 100 is placed over the subject 1536. In this example the receive magnetic resonance antenna 100 has two mounts 1529 which attach the antenna 100 to the subject support 1534 in with a controlled geometric relationship. This for example may be used to better estimate the dose received by the subject 1536. It can be seen that the radiation beam 1542 passes through the radiation zone 208 and for the most part avoids the first reduced radiation zone 202 and the second reduced radiation zone 206.

[0123] The transmit coil 1528 may also be constructed similarly to the coil 100. Discrete components may be moved out side of the path of the beam 1542.

[0124] The transceiver 1530, the magnetic field gradient coil power supply 1526 and the mechanical positioning system 1537 are all shown as being connected to a hardware interface 1546 of a computer system 1544. The computer system 1544 is shown as further comprising a processor 1548 for executing machine executable instructions and for controlling the operation and function of the medical apparatus. The hardware interface 1546 enables the processor 1548 to interact with and control the medical apparatus 1500. The processor 1548 is shown as further being connected to a user interface 1550, computer storage 1552, and computer memory 1554.

[0125] The computer storage 1552 is shown as containing a treatment plan 1560. The computer storage 1552 is further shown as containing a pulse sequence 1562. A pulse sequence as used herein is a set of commands used to control various components of the magnetic resonance imaging system 1504 to acquire magnetic resonance data 1564. The computer storage 1552 is shown as containing magnetic resonance data 1564 that was acquired using the magnetic resonance imaging system 1504.

[0126] The computer storage 1552 is further shown as containing a magnetic resonance image 1566 that was reconstructed from the magnetic resonance data 1564. The computer storage 1552 is further shown as containing an image registration 1568 of the magnetic resonance image 1566. The image registration 1568 registers the location of the image relative to the magnetic resonance imaging system 1504 and the LINAC 1502. The computer storage 1552 is further shown as containing the location 1570 of the target zone 1538. This was identified in the magnetic resonance image 1566. The computer storage 1552 is further shown as containing control signals 1572. The control signals 1572 are control signals which are used to control the LINAC 1502 to irradiate the target zone 1538.

[0127] The computer memory is shown as containing a control module 1580. The control module contains computer-executable code which enables the processor 1548 to control the operation and function of the medical apparatus 1500. For instance the control module 1580 may use the pulse sequence 1562 to acquire the magnetic resonance data 1564. The control module 1580 may also use the control signals 1572 to control the LINAC 1502. The computer memory 1554 is further shown as containing a treatment plan modification module 1582. The treatment plan modification module 1582 modifies the treatment plan 1558 using the image registration 1568. The computer memory 1554 is shown as further containing an image reconstruction module 1584. The image reconstruction module 1584 contains code which enables the processor 1548 to reconstruct the magnetic resonance image 1566 from the magnetic resonance data 1564.

[0128] The computer memory 1554 is shown as further containing an image registration module 1586. The image registration module 1586 contains code which enables the processor 1548 to generate the image registration 1568 in the location of the target zone 272 using the magnetic resonance image 1566. The computer memory 1554 is shown as further containing a target zone location module 1588. The target zone location module 1588 contains code which enables the processor 1548 to generate the location of the target zone 1570 using the image registration 1568. The computer memory 1554 is further shown as containing a control signal generation module 290. The control signal generation module 290 contains code which enables the processor 1548 to generate the control signals 1572 from the treatment plan 1560 and the location of the target zone 1570. The treatment plan 1560 after it has been modified.

[0129] FIG. 16 shows a flowchart which illustrates a method of operating the medical apparatus 1500 of FIG. 15. In step 1600 a treatment plan 1560 is received. In step 1602 a processor controls the magnetic resonance imaging system 1504 to acquire the magnetic resonance data 1564. Next in step 1604 the processor reconstructs the magnetic resonance image 1566 from the magnetic resonance data 1564. Next in step 1606 the processor registers the location of the target zone 1570 and the magnetic resonance image 1566. This creates an image registration 1568. Next in step 1572 the processor generates the control signals 1572 using the location of the target zone 1570 and the treatment plan 1560. The processor likely also references a model of the apparatus 1560 to generate the correct commands. Finally in step 1610 the processor controls the X-ray radiation source of the LINAC to irradiate the target zone 1538 using the control signals 1572.

[0130] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

[0131] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

LIST OF REFERENCE NUMERALS

[0132] 100 magnetic resonance antenna [0133] 102 outer layer [0134] 104 flexible printed circuit board [0135] 106 coil former [0136] 108 biocompatible layer [0137] 202 first reduced radiation zone [0138] 204 irradiation zone [0139] 206 second reduced radiation zone [0140] 208 first edge [0141] 210 second edge [0142] 300 cross sectional view [0143] 302 concave surface [0144] 400 cross section [0145] 402 preamplifier and other electronics [0146] 404 copper strips of antenna elements [0147] 406 PIN diode and other electronics [0148] 408 flat copper conductors [0149] 500 cross sectional view [0150] 600 cross sectional view [0151] 700 cross sectional view [0152] 800 cross sectional view [0153] 802 electrical connection [0154] 900 cross sectional view [0155] 1000 cross sectional view [0156] 1100 structure of printed circuit board [0157] 1400 X-ray radiation beam [0158] 1402 nominal beam width [0159] 1404 iso center [0160] 1406 100% dose [0161] 1408 2% dose [0162] 1500 mecical apparatus [0163] 1502 LINAC [0164] 1504 magnetic resonance imaging system [0165] 1506 gantry [0166] 1508 X-ray source [0167] 1510 adjustable collimator [0168] 1512 magnet [0169] 1514 cryostat [0170] 1516 superconducting coil [0171] 1522 bore [0172] 1524 magnetic field gradient coil [0173] 1526 magnetic field gradient coil power supply [0174] 1528 transmit antenna [0175] 1530 transciever [0176] 1532 imaging zone [0177] 1534 subject support [0178] 1536 subject [0179] 1537 mechanical positioning system [0180] 1538 target zone [0181] 1540 axis of gantry rotation [0182] 1542 radiation beam [0183] 1543 gap [0184] 1544 computer system [0185] 1546 hardware interface [0186] 1548 processor [0187] 1550 user interface [0188] 1552 computer storage [0189] 1554 computer memory [0190] 1560 treatment plan [0191] 1562 pulse sequence [0192] 1564 magnetic resonance data [0193] 1566 magnetic resonance image [0194] 1568 image registration [0195] 1570 location of target zone [0196] 1572 control signals [0197] 1580 control module [0198] 1582 treatment plan modification module [0199] 1584 image reconstruction module [0200] 1586 image registration module [0201] 1588 target zone location module [0202] 1590 control signal generation module [0203] 1600 receive a treatment plan for irradiating the target zone [0204] 1602 acquire the magnetic resonance data using the magnetic resonance imaging system [0205] 1604 reconstruct a magnetic resonance image from the magnetic resonance data [0206] 1606 register a location of the target zone in the magnetic resonance image [0207] 1608 generate control signals in accordance with the location of the target zone and the treatment plan [0208] 1610 control the X-ray radiation source of the LINAC to irradiate the target zone using the control signals