Tool for implanting a fiducial marker

What is claimed is:

1. An apparatus for inserting a fiducial marker component into a patient, comprising:

a housing that is generally cylindrically shaped and which has a bore provided therein, said housing having a proximal end and a distal end, at least a portion of the proximal end of the housing flaring outward from the body of the housing so as to provide an area for stably supporting the housing against a surface on a patient;

a cannula guide tube assembly that has a proximal end and a distal end and which contains a bore;

a drill for forming a bore hole at an implantation site; and

an inserter for inserting a fiducial marker component in the bore hole at the implantation site;

wherein the cannula guide tube is shiftable within said bore of said housing and the drill and inserter are each separately insertable into said guide tube and shiftable therein.

2. The apparatus for inserting a fiducial marker component according to claim 1, wherein the housing has a longitudinal axis and wherein the portion of the cylindrical housing that flares outward forms a flange at the housing than extends in a perpendicular direction away from the longitudinal axis of the housing.

3. The apparatus for inserting a fiducial marker component according to claim 1, wherein said guide tube is provided with teeth.

4. The apparatus for inserting a fiducial marker component according to claim 1, wherein said guide tube has an outer surface on which is provided at least one abutment surface near said distal end of the guide tube to contact the housing and thereby limit movement of the guide tube with respect to the housing.

5. The apparatus for inserting a fiducial marker component according to claim 1, further comprising a spring disposed within the bore of said housing such that said guide tube fits within said housing and is shiftable therein against a force provided by said spring.

6. The apparatus nor inserting a fiducial marker component according to claim 1, further comprising an obturator assembly that is separately insertable into the guide tube and shiftable therein separately from the drill and the inserter.

7. The apparatus for inserting a fiducial marker component according to claim 6, wherein said obturator assembly further comprises a handle and an obturator shaft that has a smaller diameter than the bore of the guide tube, wherein the obturator shaft is affixed to said handle.

8. The apparatus for inserting a fiducial marker component according to claim 1, wherein said drill comprises a handle and a drill bit having a smaller diameter than the bore of the guide tube, said drill bit being disposed in said handle.

9. The apparatus for inserting a fiducial marker component according to claim 1, wherein said inserter comprises a driver shaft and a handle to which the driver shaft is attached, wherein the diameter of the shaft is smaller than the diameter of the housing bore.

10. The apparatus of claim 9, further comprising a cylindrically-shaped clip that is sized to grip the shaft of the driver.

11. The apparatus for inserting a fiducial marker component according to claim 1, further comprising a trocar assembly that is insertable into the guide tube and shiftable therein.

12. The apparatus for inserting a fiducial marker component according to claim 11, wherein said trocar assembly further comprises a handle and an trocar shaft that has a smaller diameter than said guide tube bore, one end of said trocar shaft terminating in a sharp point and wherein the other end of the trocar shaft is affixed to said handle.

13. An apparatus for inserting a fiducial marker component, comprising:

a housing defining an axially disposed bore, wherein the diameter of the bore is stepped so as to define a shoulder, said housing having a proximal end and a distal end, at least a portion of the proximal end extending laterally away from the bore so as to provide an area for stably supporting the housing against a surface;

a cannula, said cannula having a proximal end, a distal end, an exterior surface and a shoulder attached to the exterior surface of the cannula between the proximal and distal ends of the cannula; and

a spring located within the bore of the housing and bound at its ends by the bore shoulder and the cannula shoulder, wherein the cannula is freely shiftable within the bore so as to limit the length of the spring.

14. The apparatus for inserting a fiducial marker component of claim 13, further comprising an insertion tool that is separately insertable into the cannula and shiftable therein, said insertion tool comprising a metal shaft.

15. The apparatus for inserting a fiducial marker component of claim 14, wherein the insertion tool further includes a clip for affixing a cylindrical object to the terminus of the shaft.

16. The apparatus for inserting a fiducial marker component of claim 14, wherein the insertion tool includes a handle at one end of the shaft and a drive element at the tip of the other end of the shaft.

17. The apparatus for inserting a fiducial marker component of claim 13, further comprising a drill having a shaft that is insertable into the cannula and shiftable therein.

18. The apparatus of claim 17, wherein the drill is a hand drill.

19. The apparatus of claim 17, wherein the drill is a power drill.

20. The apparatus for inserting a fiducial marker component of claim 18, wherein the cannula has an upper external surface that defines an abutment surface, the drill has a facing abutment surface, and wherein the drill can be inserted into the cannula up to the point at which the abutment surface of the drill contacts the abutment surface of the cannula, thereby limiting the depth of hole that can be made by the drill.

21. The apparatus for inserting a fiducial marker component of claim 13, wherein the housing has an annular flange at one of its ends.

22. The apparatus for inserting a fiducial marker component of claim 13, wherein the cannula has means for gripping an underlying surface at one of its ends.

23. The apparatus for inserting a fiducial marker component of claim 13, wherein the cannula is affixed to a knob containing a bore.

24. The apparatus for inserting a fiducial marker component of claim 23, further comprising a clip having attachment means to affix a fiducial marker component with respect to the terminal portion of the shaft of an insertion tool, and wherein the bore in the knob of the cannula includes a seat for the clip.

25. The apparatus for inserting a fiducial marker component of claim 24, wherein the clip comprises:

a cylindrical portion defining a bore; and

means distributed along the outer circumference of the clip for seating with the bore in the knob of the cannula.

26. The apparatus for inserting a fiducial marker component of claim 25, wherein the cylindrical portion of the clip further includes a plurality of inwardly directed prongs that are elastically displaceable with respect to each other.

27. The apparatus for inserting a fiducial marker component of claim 26, wherein the prongs of the clip terminate in an inwardly directed projection.

28. The apparatus for inserting a fiducial marker component of claim 25, wherein a series of inwardly directed hubs are circumferentially arrayed along the interior of the cylindrical portion of the clip.

29. The apparatus for inserting a fiducial marker component of claim 13, wherein the housing is made of plastic.

30. The apparatus for inserting a fiducial marker component of claim 13, wherein the cannula is made of metal.

31. The apparatus for inserting a fiducial marker component of claim 13, further including a fiducial marker component comprising a fiducial marker base that is adapted to be inserted through the cannula.

32. The apparatus for inserting a fiducial marker component of claim 31, wherein the fiducial marker base has self tapping threads.

33. The apparatus for inserting a fiducial marker component of claim 13, further including a fiducial marker component comprising a fully implantable fiducial marker that is adapted to be inserted through the cannula.

34. The apparatus for inserting a fiducial marker component of claim 13, wherein the cannula shoulder is in the form of a ring.

35. A tool kit for facilitating the insertion of a cylindrical object into a hole in a portion of anatomy of a patient, comprising:

a housing having two ends, one of which extends from the housing an amount sufficient to provide an area for stably supporting the housing against a surface on the patient;

a spring-loaded cannula that is shiftable within the housing;

a drill for forming a hole, said drill being shiftable within the cannula; and

an insertion tool for driving a cylindrical object into the hole formed by the drill.

36. The tool kit of claim 35, further comprising an obturator that is separately shiftable within the cannula.

37. The tool kit of claim 35, further comprising a trocar that is separately shiftable within the cannula.

38. The tool kit of claim 35, further comprising a tool for removing the cylindrical object from the hole.

39. The tool kit of claim 35, further including a cylindrical object comprising a fiducial marker.

40. The tool kit of claim 35, further including a cylindrical object comprising a temporary marker base.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for implanting a fiducial marker. More specifically, the invention relates to an apparatus and method that provide for the creation of a hole that does not penetrate the entire thickness of a segment of bone, and which is sized to accommodate a fiducial marker. The invention also provides for the insertion of an imaging marker or marker base into the hole so created.

Recent years have seen the development of diagnostic techniques that allow the practicing clinician to obtain high fidelity views of the anatomical structure of the human body. Imaging systems such as computed tomographic (CT) x-ray imagers, positron emission tomographic (PET) scanners, single photon emission computed tomography (SPECT) scanners and nuclear magnetic resonance imaging (MRI) machines have provided clinicians with the ability to improve visualization of the anatomical structure of the human body without surgery or other invasive techniques. In lieu of exploratory surgery, the patient can be scanned by such imaging systems, and the patient's anatomical structure can be reproduced in a form for evaluation by a trained doctor. A problem associated with such scanning techniques concerns the accurate selection and comparison of views of identical areas in images that have been obtained by imagers at different times or by images obtained essentially at the same time using different image modalities, e.g., CT, MRI, SPECT, and PET. This problem has two aspects. First, in order to relate the information in an image of the anatomy to the anatomy itself, it is necessary to establish a one-to-one mapping between points in the image and points of anatomy. This is referred to as registering image space to physical space.

The second aspect concerns the registration of one image space onto another image space. The goal of registering two arbitrarily oriented three dimensional images is to align the coordinate systems of the two images such that any given point in the scanned anatomy is assigned identical addresses in both images. The calculation of the rigid body transformation necessary to register the two coordinate systems requires knowledge of the coordinate vectors of at least three points in the two systems. Such points are called "fiducial points" or "fiducials," and the fiducials used are the geometric centers of markers, which are called "fiducial markers". These fiducials are used to correlate image space to physical space and to correlate one image space to another image space. The fiducial markers provide a constant frame of reference visible in a given imaging mode to make registration possible.

The general technique for using fiducial markers to obtain registration of image data is set forth in U.S. Pat. No. 4,991,579 and U.S. Pat. No. 5,142,930, the contents of both of which are incorporated herein by reference. Briefly, these patents teach implanting within a patient a series of at least three fiducial markers whose location can be determined in the image space of an imager.

Broadly speaking, image markers can be either temporary or permanent with respect to the duration of their placement within the human body. Permanent markers are unitary in construction, and are placed entirely beneath the epidermis of the skin for extended periods of time. Temporary markers have two parts: a base that is implanted into bone, and a temporary image marker portion that is attached to the base for brief intervals of time. In the temporary marker, the image marker portion protrudes from the skin.

In both the temporary and the permanent markers, the marker portion may take the form of a hollow container that is charged with aqueous imaging agents to provide imaging capability in the desired imaging modality or modalities. Patent application Ser. No. 08/017,167 (the contents of which are incorporated herein by reference) more fully discusses the structure of each type of marker and the imaging agents which can be used therewith.

Whichever type of marker is employed, it is necessary for the clinician to implant the marker into some solid, dimensionally stable portion of the anatomy. The preferred location for the placement of fiducial markers is bone, as it is generally dimensionally stable, and can provide a secure anchor site for a fiducial marker. The placement of a fiducial marker into bone requires that a hole be drilled for the fiducial marker.

Permanent fiducial markers typically are implanted in their entirety in bone tissue beneath the skin; temporary markers (as noted above) have distinct base and marker portions, with respect to which only a portion of the base need be implanted into bone. One method for implanting a fiducial marker is described in U.S. Pat. No. 5,178,164, which is incorporated herein by reference. According to this method, a marker is screwed into bone tissue under force. A hex-key like wrench engages a socket on the upper surface of the marker to provide the necessary drive connection between the two elements.

Numerous surgical tools have been developed to facilitate the insertion of foreign objects into the human body. Recent years, in particular, have seen the development of very specialized tools for many surgical procedures so as to minimize the invasiveness of the procedure in question. One such specialized tool is an apparatus for the insertion of a catheter into the ventricular portion of the brain, and is set forth in U.S. Pat. No. 4,931,056, which is incorporated herein by reference. The patent discloses a catheter guide apparatus comprising a hand operated twist drill device, configured for insertion in a first tubular guide. A second guide, of reduced diameter relative to the first tubular guide, is insertable into the first guide upon completion of a through-hole in the skull and subsequent removal of the twist drill, to facilitate entry of a catheter into the ventricle portion of the brain.

There remains a need for a tool specialized to facilitate the creation of a hole that is configured to accommodate a fiducial marker. There further remains a need for a tool that can quickly be reconfigured to facilitate the secure insertion of a fiducial marker into the hole so created. There further remains a need for a tool especially adapted for the insertion of a fiducial marker into bone tissue that is simple to use, minimally invasive, and which includes safety features to prevent the formation of an unwanted through-hole in bone tissue.

SUMMARY OF THE INVENTION

The present invention provides a tool for first creating a hole of predetermined depth into bone tissue, and then inserting a fiducial marker into the hole in the bone. The tool uses a guide assembly and means that cooperate with the guide assembly for perforating the skin, securely siting the guide assembly, forming the bore hole, and inserting the marker.

Before using the tool, the physician first determines the site at which the fiducial marker is to be inserted and marks that site with an incision. The insertion tool is then placed over the incision. The tool provides a guide assembly that includes a housing that is shaped to provide a secure abutment with respect to a desired portion of the anatomy of a patient. The housing contains a bore which accommodates both a cylindrical metal cannula and a spring that is entrained between a ring on the cannula and a shoulder within the housing; the cannula is shiftable within the housing against a force supplied by this spring. One end of the cannula terminates in a row of sharp teeth for establishing a firm connection between the housing and the patient's tissue. The other end of the cannula is inserted within a handle having an opening that leads to the hollow cannula. The cannula is sized to accommodate a number of implements useful in establishing a hole of proper size and inserting a marker, including an obturator, a hand drill, and a specialized insertion tool. After the incision has been made, an obturator having a sharp tip at its proximal end is inserted into the cannula. The length of the obturator is sufficient for a length of it to protrude beyond the proximal end of the cannula so that its pointed tip can be brought into contact with the incision site. The initial positioning of the guide assembly is accomplished simply by a downward shifting of the housing and the guide assembly along the length of the obturator until the teeth of the cannula contact tissue. The housing is then axially shifted along the cannula against the spring entrained between the cannula and the housing, until the housing abuts the patient's skin.

Once the tool housing is properly sited, the obturator is removed from the cannula and a hand drill inserted in its place. The hand drill is used to make a hole of predetermined diameter and depth (the depth of the hole drilled is limited by the manner in which the geometry of the housing, drill bit and drill bit length cooperate with one another). The hand drill is then removed from the cannula.

The tool can be used to insert either the marker base of a temporary fiducial marker or a permanent, fully implantable fiducial marker. Where a temporary marker is to be installed, its base, which may have a polygonal socket, is attached to the end of an insertion tool that terminates in a drive element. The insertion tool and marker base are then inserted into the cannula. By pressing the fiducial marker base into the hole and then rotating the handle of the insertion tool, the marker base (which has a self-tapping thread) can be screwed into the hole formed by the hand drill. The insertion tool is then pulled away from the fiducial marker base and is removed from the cannula. The procedure for inserting a permanent fiducial marker is similar, differing chiefly in that instead of screwing in the marker, it is press-fitted into the hole. At this point the procedure is complete, and the guide assembly is removed from the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying figures, in which:

FIG. 1 is a cross-sectional view of the guide assembly;

FIG. 2 shows the cannula guide tube subassembly, partially in section;

FIG. 3 shows the obturator and its engagement with the guide assembly;

FIG. 4 shows the position of the guide assembly and obturator when the obturator is sited over the insertion site;

FIG. 5A is a plan view of the hand drill;

FIGS. 5B and 5C are side and end views, respectively, of a drill bit employed with the hand drill;

FIGS. 5D and 5E are side and end views, respectively, of the handle portion of the hand drill;

FIG. 6 is a side view, partially in section, of the hand drill inserted in the guide assembly;

FIG. 7A shows a temporary marker base that can be used with the present invention;

FIG. 7B shows a permanent marker that can be used with the present invention;

FIG. 8 is a side view, partially in section, of the cooperation between the insertion tool, clip, and temporary marker base;

FIG. 9A is a perspective view of the clip shown in FIG. 8, which helps secure the temporary marker base to the insertion tool;

FIG. 9B is a side-sectional view of a clip which is configured to secure a permanent marker to the insertion tool;

FIG. 9C is an end view of the clip shown in FIG. 9B;

FIG. 10 is a sectional view showing the insertion tool, the temporary marker base and guide housing, in which the cannula guide tube is shown shifted with respect to the guide housing;

FIG. 11 is a magnified view of the proximal end of FIG. 10, and highlights the tip of the proximal end of the cannula and the threaded portion of the temporary marker base;

FIGS. 12A-12C provide perspective views of the principal elements of the tool kit, including the guide assembly (FIG. 12A), insertion tool (FIG. 12B) and obturator (FIG. 12C);

FIGS. 13A and 13B are partial side sectional and end views, respectively, of a tool for removing the base of a temporary fiducial marker after it has been inserted; and

FIGS. 14A and 14B illustrate the use of an additional embodiment that employs a trocar instead of an obturator in a two-stage process. FIG. 14A is a sectional view of the embodiment at a first stage of its use and FIG. 14B is an elevational view of the embodiment at a second stage of its use.

DETAILED DESCRIPTION

Turning initially to FIG. 1, there is illustrated a guide assembly 10 of the present invention. The guide assembly 10 serves to provide a means for establishing and mai