Vacuum-assisted fixation apparatus - Patent Review 5464411

What is claimed is:

1. A stereotactic fixation apparatus, comprising:

a stereotactic frame; and

a mouthpiece attached to said stereotactic frame, said mouthpiece having a surface for contacting a patient's hard palate and a port positioned at a point on said mouthpiece distal of said surface and adapted for connection to a source of vacuum, said mouthpiece being configured to provide a fluidic path between said surface and said port to provide a vacuum attachment between the surface and the hard palate of the patient.

2. The stereotactic fixation apparatus of claim 1 additionally comprising a vacuum control system configured to communicate with the source of vacuum so as to regulate vacuum from said source of vacuum and a remote patient-activated switch which communicates with said vacuum control system for terminating vacuum pressure in the fluidic path defined by said mouthpiece.

3. The stereotactic fixation apparatus of claim 1, wherein said surface is shaped to conform to the hard palate of the patient.

4. The stereotactic fixation apparatus of claim 3, additionally comprising a normally closed, one-directional flow valve in communication with the fluidic path provided between said surface and said port of said mouthpiece.

5. The stereotactic fixation apparatus of claim 4, wherein said surface has at least one hole which communicates with said port, said normally closed, one-directional flow valve being in said fluidic path between said hole in said surface and said port.

6. The stereotactic fixation apparatus of claim 5, wherein said hole in said surface opens into a normally sealed cavity formed within said valve, said cavity having a volume significantly less than the volume of said fluidic path of said mouthpiece.

7. The stereotactic fixation apparatus of claim 1 additionally comprising a coupling which connects said mouthpiece to said stereotactic frame, said coupling configured to provide at least three degrees of rotational movement of said mouthpiece relative to said stereotactic frame, and at least two degrees of linear movement of said mouthpiece relative to said stereotactic frame.

8. The stereotactic fixation apparatus of claim 7, wherein said coupling is removably attached to said stereotactic frame.

9. The stereotactic fixation apparatus of claim 7, wherein said coupling includes a locking mechanism which prevents said mouthpiece from moving in reference to said stereotactic frame and which permits said mouthpiece to be repositioned in exactly the same manner to said stereotactic frame.

10. The stereotactic fixation apparatus of claim 9, wherein said coupling comprises:

a plurality of discs having a central bore formed through the center of the discs along a common axis, a first of said discs having a first bore positioned generally normal to said central bore and being positioned in said first disc so as not to intersect with said central bore, a second of said discs having at least a portion of a second bore positioned generally normal to said central bore and being positioned in said second disc so as not to intersect with said central bore;

a fastener having a shaft which passes through said central bore to join said discs together, said fastener having a first unlocked position in which said first and second discs are rotatable about said fastener shaft, and a second locked position in which said first and second discs are nonrotatable about said fastener shaft;

a substantially rigid member extending through said first bore of said first disc, said member and said first disc being adapted to permit said member to rotate about a vertical axis of said member when said fastener is in said unlocked position, and to prevent said member from rotating about said vertical axis of said member when said fastener is in said locked position, said member being connected to said port of said mouthpiece; and

a rod adapted to attach to said stereotactic frame, said rod extending through said second bore of said second disc, said rod and said second disc being adapted to permit said second disc to rotate about a longitudinal axis of said rod when said fastener is in said unlocked position, and to prevent said second disc from rotating about said longitudinal axis of said rod when said fastener is in said locked position.

11. The stereotactic fixation apparatus of claim 10, wherein said first bore breaks through a flat lateral surface of said first disc to an extent that no more than an arc length of 30.degree. of an exterior surface of said rigid member extends beyond said flat lateral surface of said first disc with said rigid member extending through said first bore.

12. The stereotactic fixation apparatus of claim 10, wherein said second bore passes through an interface between said second disc and a third disc, a portion of said second bore extending into said third disc.

13. The stereotactic fixation apparatus of claim 10, wherein said rigid member is connected to a source of vacuum.

14. The stereotactic fixation apparatus of claim 1, wherein said mouthpiece comprises an impression of the patient's upper teeth and hard palate.

15. The stereotactic fixation apparatus of claim 14, wherein said mouthpiece additionally comprises a tray onto which said impression is mounted.

16. The stereotactic fixation apparatus of claim 1 additionally comprising a vacuum control system having a remote patient-activated switch which is configured to be held by a patient and which communicates with and controls a valve that is positioned in fluidic communication with said mouthpiece.

17. A fixation apparatus, comprising:

a platform for supporting a body of a patient;

a skull immobilization device contacting said platform at least at one interface region; and

a port adapted for connection to a source of vacuum, said port being in fluidic communication with said interface region and formed in said platform or in said skull immobilization device whereby a vacuum holds said immobilization device against said platform when vacuum pressure is applied to said interface region through said port.

18. The fixation apparatus of claim 17, wherein said immobilization device comprises a stereotactic frame.

19. The fixation apparatus of claim 18, wherein said stereotactic frame has at least two footings which contact said platform at two interface regions, each of said interface regions including a cavity that is in fluidic communication with said port.

20. The fixation apparatus of claim 19, wherein at least one of said cavities is formed in one of said footings

21. The fixation apparatus of claim 19, wherein said at least one of said cavities is formed in said platform.

22. The fixation apparatus of claim 19, further comprising at each of said interface regions an O-ring compressed between said platform and each corresponding footing for forming a seal around each of said cavities.

23. The fixation apparatus of claim 22, wherein at least one of said O-rings is seated in a groove formed in said platform.

24. The fixation apparatus of claim 23 additionally comprising means for positioning at least one of said footings, on said platform such that said corresponding O-ring surrounds the periphery of said corresponding cavity.

25. The fixation apparatus of claim 17 additionally comprising a vacuum control system for communicating with at least the source of vacuum which communicates with at least said port so as to enable or disable the source of vacuum applied to said port, said vacuum control system having a remote patient-activated switch which is configured to be held by said patient and which communicates with said vacuum control system such that said vacuum control system disables the application of vacuum at said port when said patient activates said switch.

26. The fixation apparatus of claim 25, wherein said vacuum control system includes a solenoid valve configured to be positioned between and in fluidic communication with the source of vacuum and said port, said vacuum control system operating said valve in response to said patient-activated switch.

27. The fixation apparatus of claim 17, wherein said stereotactic immobilization device comprises a rigid face mask mounted to a frame, said face mask adapted to have shape which conforms to the contours of the anterior features of the patient's skull.

28. The fixation apparatus of claim 27, wherein said interface region comprises a cavity.

29. The fixation apparatus of claim 28, wherein said cavity is formed in said platform.

30. A method of accurately and reproducibly positioning a patient's skull for a medical procedure, said method comprising the steps of:

providing a mouthpiece attached to a stereotactic frame;

positioning said mouthpiece within said patient's mouth in a position in which said mouthpiece extends beneath the patient's hard palate; and

applying a vacuum to draw said mouthpiece against the patient's hard palate so as to secure said mouthpiece within the patient's mouth.

31. The method of claim 30 additionally comprising the steps of:

making an impression of the patient's upper teeth and hard palate; and

mounting said impression on a tray to form said mouthpiece.

32. The method of claim 31, wherein said step of applying a vacuum comprises drawing a vacuum between said impression and the patient's hard palate so as to draw said impression firmly against the patient's hard palate.

33. The method of claim 30 additionally comprising the steps of:

providing a coupling between said mouthpiece and said stereotactic frame, said coupling providing three degrees of rotational freedom and two degrees of axial freedom in of to said mouthpiece relative to said stereotactic frame;

adjusting the position of the patient's head to a set position with said mouthpiece secured within the patient's mouth; and

locking said coupling with said mouthpiece in said set position to prevent the coupling from rotating or moving axially in reference to said stereotactic frame.

34. The method of claim 33 additionally comprising the step of removing said coupling from said stereotactic frame with said mouthpiece remaining attached to said coupling.

35. The method defined in claim 30, wherein said step of providing a mouthpiece comprises:

making a dental impression of a patient's teeth using a first material;

making a study cast of said patient's teeth using said dental impression;

making an impression of said study cast using a second material different from said first material to provide a bite block; and

forming a passageway through said mouthpiece to provide a path for drawing said mouthpiece against the interior of the patient's mouth.

36. The method defined in claim 35 additionally comprising the step of providing a normally closed, one-directional flow valve in fluidic communication with said passageway.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for immobilizing a patient's skull during a medical diagnostic or treatment procedure, and more particularly to a stereotactic fixation apparatus which permits precise and reproducible positioning of the patient's skull for focal irradiation or like medical procedures.

2. Description of Related Art

Modern methods of imaging, such as computerized tomography and magnetic resonance imaging, enable radiation oncologist to precisely delineate volumes of diseased tissue and normal anatomical structures. The data from imaging scans makes it possible to tailor radiation doses to a particular, identifiable treatment volume.

Focal radiation treatment usually involves the use of external beams, such as, for example, photon or proton beams. Such treatment requires accurate positioning and immobilization of the patient because a small misalignment in a patient's position with respect to the external beam can result in missing the target and/or delivering the high dose of radiation to normal, non-targeted tissue. The distance from the high-dose region of the external beam to its lateral and distal edges is often but millimeters.

Radiation treatment and pretreatment diagnostic studies also requires reproducible positioning of the patient. Radiotherapy typically involves several diagnostic, planning and treatment stages. At each stage subsequent to the initial, accurate repositioning of the patient is essential. Most patients also require multiple treatments extending over several weeks. Variation of the treatment position between different sessions will decrease the efficacy of the treatment.

In an effort to provide accurate and reproducible positioning of a patient, stereotactic location devices have been developed. These devices rely on the assumption that the skull and its contents are rigid. Each anatomic point within the skull can then be uniquely identified when one knows the three spacial coordinates of that anatomic point.

Original neurosurgical and radiosurgical stereotactic location devices typically attach to the patient's skull by three or four pins surgically affixed. These invasive devices cannot be removed between diagnostic studies and treatment procedures, which therefore have to be performed within one day.

More recently, a relocatable stereotactic location device has been developed which employs a halo-ring which is invasively attached to the patient's skull and remains in place for several weeks unless the treatment is finished. An example of these devices are described in Clark, B. G., et al., "A Halo-Ring Technique for Fractionated Stereotactic Radiotherapy," The British Journal of Radiation, pp. 522-527 (June 1993). Such devices, however, are still invasive and may cause discomfort to the patient.

Another prior relocatable stereotactic device is described in Delannes, M., et al., "The Laitinen Stereoadaptor," Neurochirurgie, 1990, 36:167-175. This device can be quickly positioned on the patient's head using two ear plugs and a nasal support to locate the device on the skull. However, because these fixation points contact relatively soft tissue, such device inherently lacks the rigidity and reproducibility of bony or dental fixation.

Another prior stereotactic device has also used the upper teeth or alveolar ridge to position the stereotactic device on the patient's skull. The rigid connection between the upper teeth and the skull make the upper teeth a convenient and non-invasive reference point of the skull. This stereotactic device is disclosed in U.K. Patent Publication 2 213 066. Straps or similar structure are used in these devices to secure a mouthpiece of the stereotactic device within the patient's mouth. These straps, however, are awkward and time consuming to use, and can contribute to misalignment in head position. In addition, such straps cannot be easily and immediately removed in exigent circumstances. For instance, in cases where the patient chokes, vomits, or otherwise has trouble breathing, the mouthpiece cannot be quickly removed either by the health care provider or by the patient. In addition, a health care provider may also not immediately recognize the patient's condition because the stereotactic location device has immobilized the patient's head, and the patient may be unable to alert the health care provider of his or her condition.

Another disadvantage of using straps is that they may be variably located in the radiation treatment field, thus compromising the quality and reproducibility of dose delivery, especially where charged particles, such as protons, are used.

SUMMARY OF THE INVENTION

In view of the foregoing drawbacks and shortcomings of the prior stereotactic location devices, a need exists for a stereotactic location device which is noninvasive, provides sufficient immobilization, allows accurate re-positioning, is well tolerated by a patient, is quickly released and does not interfere with the medical procedure (e.g., interfere with an external beam in radiotherapy).

In accordance with one aspect of the present invention, a stereotactic fixation apparatus comprises a mouthpiece attached to a stereotactic frame. The mouthpiece has a surface that contacts tissue of a patient, particularly the patient's hard palate, and also has a port adapted for connection to a source of vacuum. Additionally, the mouthpiece is configured to provide a fluidic path between the surface and the port. In the preferred embodiment, the surface of the mouthpiece is shaped to conform to the hard palate of the patient and has at least one hole that communicates with the port. A normally closed, one-way flow valve may be positioned in the fluidic path between the hole and the port. Additionally, the apparatus preferably includes a vacuum control system which regulates the vacuum and a patient-activated switch for terminating vacuum pressure in the fluidic path.

A further aspect of the present invention relates to a stereotactic fixation apparatus that comprises a platform for supporting the body of a patient. A stereotactic immobilization device, such as a stereotactic frame, contacts the platform at least at one interface region. A port, connected to a source of vacuum, is in fluidic communication with the interface region. When a vacuum pressure is applied to the interface region through the port, the vacuum holds the stereotactic immobilization device against the platform. Preferably, the above-mentioned patient-actuated switch serves to terminate vacuum pressure not only to the mouthpiece, but also to the stereotactic immobilization device.

According to another aspect of the invention, a method of accurately and reproducibly positioning a patient's skull for a medical procedure involves the use of a mouthpiece attached to a stereotactic frame. The mouthpiece is positioned within the patient's mouth so as to extend beneath the patient's hard palate. A vacuum is applied to draw the mouthpiece against the patient's hard palate so as to secure the mouthpiece within the patient's mouth.

Yet another aspect of the invention comprises a method of manufacturing a mouthpiece for a stereotactic fixation apparatus. A dental impression of a patient's teeth is made using a first material, and a study cast of the patient's teeth is made using the dental impression. An impression of the study cast is then made using a second material different from the first material to provide a bite block. A passageway is formed through the mouthpiece to provide a path for drawing the mouthpiece against the interior of the patient's mouth.

An additional aspect of the invention comprises a coupling that couples a stereotactic frame to a mouthpiece. The coupling is configured to provide at least three degrees of rotational movement of the mouthpiece relative to the stereotactic frame and at least two degrees of linear movement of the mouthpiece relative to the stereotactic frame.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate and not the limit the invention, and in which:

FIG. 1 is a top perspective view a vacuum-assisted stereotactic fixation apparatus in accordance with one preferred embodiment of the present invention;

FIG. 2 is a schematic front elevational view of the stereotactic fixation apparatus of FIG. 1;

FIG. 3 is an exploded top perspective view of the stereotactic fixation apparatus of FIG. 1;

FIG. 4 is a cross-sectional view of a footing of a stereotactic frame taken along line 4--4 of FIG. 1;

FIG. 5a is a schematic top plan view of the stereotactic fixation apparatus of FIG. 1 with the stereotactic frame in a first treatment position;

FIG. 5b is a schematic top plan view of the stereotactic fixation apparatus of FIG. 1 with the stereotactic frame in a second treatment position;

FIG. 5c is a schematic top plan view of the stereotactic fixation apparatus of FIG. 1 with the stereotactic frame in a third treatment position;

FIG. 6 is a front elevational view of a mouthpiece/coupling assembly attached to the stereotactic frame of FIG. 1;

FIG. 7 is a side elevational view of the stereotactic frame and mouthpiece/coupling assembly taken along line 7--7 of FIG. 6;

FIG. 8 is a top plan view of the stereotactic frame and mouthpiece/coupling assembly of FIG. 6;

FIG. 9 is an enlarged top perspective view of the mouthpiece/coupling assembly of FIG. 1;

FIG. 10 is a cross-sectional view of the mouthpiece taken along line 10--10 of FIG. 9; and

FIG. 11 is an exploded top perspective view of a stereotactic fixation apparatus in accordance with a second preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a stereotactic fixation apparatus 10 configured in accordance with a preferred embodiment of the present invention. The stereotactic fixation apparatus 10 is designed to immobilize a patient's skull, and is typically used with focal radiation therapy involving proton beam treatment. It is contemplated, however, that the present stereotactic fixation apparatus can be used in connection with a variety of medical diagnostic and treatment procedures.

With reference to FIG. 1, the stereotactic fixation apparatus 10 principally comprises a generally flat adaptor board or platform 12 supporting a stereotactic frame 14. A vacuum interface is used to secure the frame 14 to the adaptor board 12, as discussed in detail below.

A coupling or universal joint 16 extends outwardly from the frame 14 and supports a mouthpiece 18. The universal joint 16, which connects the mouthpiece 18 to the frame 14, allows a wide range of different positions and orientations of the mouthpiece 18 in relation to the stereotactic frame 14. Once set in a desired position, the universal joint 16 is locked and remains attached to the mouthpiece 18 throughout all subsequent planning and treatment phases of the patient's course. In this manner, the universal joint 16 forms a mechanical memory of the patient's head position with respect to the stereotactic frame 14.

The mouthpiece 18 includes a bite block 20 formed as an impression of the patient's upper mouth. A vacuum is used to removably secure the mouthpiece 18 onto the hard palate and upper teeth of the patient. For this purpose, the mouthpiece 18 connects to a vacuum source via a rigid tube 22, which passes through the universal joint 16 and connects to a flexible vacuum line 24. The mouthpiece 18 is also configured to provide a fluidic path between a port 26 to which the tube is connected and at least one hole 28 in an upper surface 30 of the bite block 20. When used, a vacuum is applied between the mouthpiece 18 and the patient's upper mouth to precisely position and secure the bite block 20 to the patient's dentition and hard palate.

With reference to FIG. 2, the stereotactic fixation apparatus 10 may also include a patient-activated quick-release mechanism with a safety interlock. This quick-release mechanism includes a patient-activated switch 32 connected to a vacuum control system 34. The vacuum control system 34 controls the application of vacuum pressure to the mouthpiece 18 and to the vacuum interface between the stereotactic frame 14 and the adaptor board 12, as discussed in detail below. When the patient activates the switch 32, the vacuum control system 34 disconnects the vacuum sources from the mouthpiece 18 and the adaptor board 12/stereotactic frame 14 interface so that the patient can dislodge the mouthpiece 18 from his or her mouth, as well as remove the frame 14 from a position surrounding the patient's head.

The vacuum control system 34 also electronically communicates via line 36 with a medical diagnostic or treatment device (not shown), such as, for example, a CAT (computer axial tomography) or MRI (magnetic resonance image) scanner, or an irradiation treatment machine. When the patient activates the switch 32, the control system 34 deactivates the medical diagnostic or treatment apparatus so as not to expose non-target site tissue to any irradiation emitted by the diagnostic or treatment apparatus.

For purposes of describing the preferred embodiment, a coordinate system is provided as illustrated in FIG. 1. Additionally, as used herein, "the longitudinal direction" refers to a direction substantially parallel to the longitudinal axis. "The lateral direction" and "the vertical direction" are likewise in reference to the lateral axis and vertical axis, respectively.

The individual components of the stereotactic fixation apparatus 10 will now be described in detail with reference to FIGS. 1-10.

Adaptor Board

FIGS. 1-3 best illustrate the adaptor board 12. The adaptor board 12 generally has a rectangular shape sized to support an adult body in a supine position. The adaptor board 12 desirably has a size and shape which is coextensive with conventional gurneys or hospital diagnostic and treatment tables. The adaptor board 12 can thus be placed onto a diagnostic or treatment table or gurney when a medical procedure is preformed using the present stereotactic fixation apparatus 10. It is also contemplated that the adaptor board 12 can alternatively be integrally formed with a dedicated diagnostic or radiation therapy treatment table or gurney.

As illustrated in FIG. 3, the adaptor board 12 may include a rectangular-shaped plank 38 which cantilevers from a superior end 40 of the adaptor board 12. The plank 38 has a width and a length slightly larger than that of a human skull. In an exemplary embodiment, the plank 38 has a length approximately equal to 10 inches (25.4 cm) and a width approximately equal to 8 inches (20.3 cm). It is understood, however, that the plank 38 could have a variety of shapes and sizes, depending upon the specific application of the stereotactic fixation apparatus 10.

The adaptor board 12, proximate to its superior end 40, defines a first rectangular recess 42 positioned generally symmetric with a longitudinal axis of the adaptor board 12. The recess 42 has a length that extends from a point proximate to the superior end 40 into the plank 38. The recess 42 is sized to receive a portion of a headrest 44 (see FIG. 3), which supports the patient's head and neck during the medical procedure.

The adaptor board 12 additionally includes a second rectangular recess 43 also positioned generally symmetrically with the longitudinal axis of the adaptor board 12. The second recess 43 is located below the first recess 42, and has a shape and size substantially identical to those of the first recess 43.

As illustrated in FIG. 3, the headrest 44 used with the adaptor board or platform 12 has an arcuate upper surface 46 which cradles the patient's skull and the nape of the patient's neck. A base 48 of the headrest 44 has a rectangular shape of a width and length generally equal to those of the recesses 42, 43 so as to be snugly received by recesses 42, 43.

The headrest 44 may be formed of any of a wide variety of material of sufficient rigidity and integrity to support the patient's head and neck. In an exemplary embodiment, the headrest 44 is vacuum-formed plastic. However, those skilled in the art will realize that the headrest 44 can be formed of a variety of different materials by a variety of different methods, known or developed in the art.

With reference to FIG. 3, the adaptor board 12 defines a series of paired stations 50 which interface with corresponding footings 52 of the stereotactic frame 14. Each station 50 includes a generally rectangularly shaped groove 54 into which a correspondingly shaped O-ring 56 is seated. The O-ring 56 is advantageously positioned on the adaptor board 12 rather than on the corresponding footing 52 because the O-ring 56 is less likely to fall off or be displaced when positioned on the adaptor board 12. However, it is contemplated that the O-ring could be secured to the frame footing 52.

The O-ring 56 desirably has a diameter larger than the depth of the corresponding groove 54. The O-ring 56 thus extends above the surface of the adaptor board 12 when seated within the groove 54.

The shape and size of each O-ring 56 desirably matches the general shape and size of the stereotactic frame footing 52. More preferably, each O-ring 56 has a corresponding shape that is slightly smaller than the periphery of the footing 52 such that with the footing 52 positioned over the O-ring 56, the entire O-ring 56 is compressed between the adaptor board 12 and the bottom surface of the footing 52.

With reference to FIG. 4, each station 50 also includes at least two holes 58 siz