Laser targeting device for use with image intensifiers in surgery

• US 5,426,687 A
• Filed: 08/10/1993
• Issued: 06/20/1995
• Est. Priority Date: 07/07/1992
• Status: Expired due to Fees

• Current Assignee: Innovative Care Limited
• Original Assignee: Innovative Care Limited
• Inventors: Goodall, John D., Young, David E.
• Primary Examiner(s): Church, Craig E.
• Application Number:
  US08/104,790
• Time in Patent Office: 679 Days
• Field of Search: 378/206, 378/205
• US Class Current: 378/206
• CPC Class Codes: A61B 17/1703 using imaging means, e.g. by X-rays
• CPC Class Codes: A61B 17/1725 for applying transverse screws or pins through intramedullary nails or pins
• CPC Class Codes: A61B 17/1764 for the knee
• CPC Class Codes: A61B 2017/00907 for light
• CPC Class Codes: A61B 2018/2025 with a pilot laser
• CPC Class Codes: A61B 2090/395 with marking agent for marking skin or other tissue
• CPC Class Codes: A61B 46/10 specially adapted for instruments, e.g. microscopes
• CPC Class Codes: A61B 6/08 Auxiliary means for directing the radiation beam to a particular spot, e.g. using light beams
• CPC Class Codes: A61B 6/4423 related to hygiene or sterilisation
• CPC Class Codes: A61B 6/508 for non-human patients
• CPC Class Codes: A61B 90/13 guided by light, e.g. laser pointers

Abstract

A laser targeting device for use during surgical procedures provides means for the precise co-axial alignment of a narrow laser beam with an x-ray beam. The device has a case which contains a reflecting mirror mounted at 45° on a low mass assembly. The mirror lies directly in front of a radio-opaque cruciform target. The case is adjustably mounted so that the image of the crosshair target may be accurately centered on the target head. A calibration aid is used to pinpoint the emanation point of the x-ray beam from the source cone of the image intensifier. The angle at which the laser beam strikes the mirror may be varied in two planes. When the crosshair image is centered and the laser beam is directed onto the emanation point the two beams are rendered precisely co-axial. Accurate drilling along the laser beam path without further recourse to x-ray screening is more accurate and eliminates direct exposure of the surgeon to irradiation during orthopedic procedures. A series of special drapes is provided for the device.

Claims

1. A laser targeting device for use during surgical procedures and adapted for attachment to an x-ray image intensifier comprising:

a. a laser light source and laser beam directing means for a laser beam emanating therefrom adapted to permit continuously variable reciprocating motion in the x-y plane about the z axis and in the x-z plane about the y axis but substantially excluding motion in the y-z plane about the x axis, said directing means being additionally adapted to provide mounting means for said laser light source;

b. a housing for said laser light source and said directing means adapted by the provision of mounting means such that said housing is always outside that part of the path of an x-ray beam produced by an x-ray source cone and which impinges upon the working area of the target head or receiver of said image intensifier;

c. a case characterized by upper and lower bounding surfaces disposed in a substantially flat and parallel manner and spaced apart by a wall suitably adapted by the provision of a hole constituting aperture means and receival means suitably disposed about said aperture means for the attachment of said mounting means of said housing, said aperture means being so sized as to permit the entry of said laser beam to the interior of said case which is adapted by the provision of adjustable mounting means which cooperate with clamping means for attachment of said laser targeting device to said target head such that said flat upper bounding surface is permitted to lie substantially flush against said target head of said image intensifier, said case being further adapted by the provision of a further hole located substantially centrally in said lower bounding surface and which is adapted to receive;

d. a plain substantially parallel sided transparent window to fit accurately said hole in said lower bounding surface said window constituting part of an assembly providing mounting means for a reflecting mirror disposed at an angle of 45 degrees to the plane in which said lower bounding surface of said case lies and also at 45 degrees to said x axis of said directing means such that when said laser beam is directed along said x-axis, through said aperture means into said case said mirror redirects said laser beam through said window along a path normal to it, said assembly being constructed from a small mass of thin walled substantially radiolucent materials and adapted to receive within that part of it which lies directly behind said mirror, a target;

said adjustable mounting means of said case permitting limited variation in the disposition of the axis normal to the centre of said window about an axis normal to the geometric centre of said target head of said image intensifier, that part of said upper and said lower bounding members of said case which overlie the working area of said target head being substantially radiolucent;

e. substantially radio-opaque target means so positioned behind said mirror within said assembly that a ray path normal to the window, if extended backwards through said mirror would pass centrally through said target means; and

f. separate calibrating means in the form of a radio-opaque marker within a suitable housing and marking guide such that when said calibration means is applied to the source cone, the point of emanation of an x-ray beam therefrom may be determined and marked,

Said means being adapted to co-operate together such that said laser beam may be rendered substantially co-axial with said x-ray beam directed towards said target head to which said laser targeting device is attached such that the path of said x-ray beam may be illuminated at its point of impingement upon an object interposed between said source cone and said target of said x-ray beam and further providing a visible reference point corresponding to the effective centre of said x-ray beam on a monitor screen with said x-ray image intensifier.

2. A laser targeting device according to claim 1, wherein laser beam directing means are in the form of

a. a turntable adapted by the provision of a slot radial to its centre of rotation, the axis of which is about the z axis and located at a suitable distance from said centre of rotation, said slot being further adapted to be engaged slidingly and intimately by a circular cam mounted eccentrically upon a shaft which is at right angles to the base of said turntable said shaft extending through to the outside of and secured to a first side of said housing which is adapted to receive it, said shaft terminating in a drive wheel by means of which said shaft may be rotated causing said turntable make angular excursions in the x-y plane about a central position, such excursions being defined by the relative dimensions of said slot, said eccentric cam and said shaft and the mounting position of said eccentric cam upon said shaft, said turntable being further adapted to receive, by the provision of mounting means in the form of bearings to permit motion at right angles to the plane of motion of said turntable of

b. a laser mount adapted by the provision of journals and including an extended portion wherein is provided a slot radial to its centre of rotation, which is about the y axis and located at a suitable distance from said centre of rotation, said slot being further adapted to be engaged slidingly and intimately by a circular cam mounted eccentrically upon a shaft which is at right angles to the base of said laser mount said shaft extending through to the outside of and secured to a second side of said housing which is adapted to receive it, said shaft terminating in a drive wheel by means of which said shaft may be rotated causing said laser mount to make angular excursions in the x-z plane about a central position, such excursions being defined by the relative dimensions of said slot, said eccentric cam and said shaft and the mounting position of said eccentric cam upon said shaft.

3. A laser targeting device according to claim 1, wherein substantially radio-opaque target means comprise an arrangement of first and second arms which are substantially co-linear and of equal length and are disposed substantially at right angles to third and fourth arms which are also substantially co-linear and of equal length, the combined lengths of said first and second arms is less than the combined length of said third and fourth arms, said arrangement being disposed behind said mirror in a substantially co-planar and contiguous manner with said mirror such that said third and fourth arms lie in the x-z plane such that the image produced on said image intensifier monitor screen represents all four arms as apparently having equal length.

4. A laser targeting device according to claim 1, wherein separate calibrating means comprises a flanged discoid moulding divided into four symmetrical recessed areas by incomplete radial slots so sized as to accommodate the nib of a typical permanent marking pen and provided with a small radio opaque spheroid at its centre.

5. A laser targeting device according to claim 1, wherein is provided a transparent semi-rigid drape, adapted so that its lower portion fits over and flush against said lower bounding surface of said case extending to the rim of said upper bounding surface, said drape is further adapted by the provision of a hinge zone which defines an overfolded upper portion substantially in the form of a flanged ring which is rendered non-entire by an interruption at the opposite side from of said hinging zone by means of which said flanged ring may be fired around said clamping means and closely around the lower part of said target head, such that said flanged ring may overlap and be secured to said lower portion of said drape over said laser targeting device and said lower part of said target head.

6. A laser targeting device according to claims 1 or 5, wherein is provided a substantially cylindrical drape generally adapted to fit in a semi-tailored fashion over said target head and specifically to close intimately over and around the upper portion of said flanged ring of said transparent semi-rigid drape which extends over the lower part of said target head by the provision near the lower border of securing means.