WO2000064223A2

WO2000064223A2 - Combined x-ray and laser projection device

Info

Publication number: WO2000064223A2
Application number: PCT/IB2000/000454
Authority: WO
Inventors: Edward Chen
Original assignee: Edward Chen
Priority date: 1999-04-17
Filing date: 2000-04-12
Publication date: 2000-10-26
Also published as: AU3666600A; WO2000064223A3

Abstract

This present invention provides an apparaus for fluorscopic imaging and projection of an X-rayed struture. This apparatus includes an X-ray source (24) and an image intensifier (40) mounted on a common support (52). A range finder (38) associated with the image intensifier (40) determines distance from the image intensifier (40) to an object being X-rayed. A computer (60) receives data from the image intensifier (40) through a video capture card (62) and processes this data. A screen (64) associated with the computer (60) permits display of the captured X-ray image. Through interfacing with the computer (60), the user may then pinpoint, highlight or outline structures or other anatomy displayed by the X-ray image, as desited. A projector (e.g. a laser projector) (46) receives data corresponding to the outline, highlight or pinpoint delineated by the user, from the compture and projects a visual image (e.g. a laser image) onto the skin of the patient at the location of the X-rayed structure or anatomy.

Description

COMBINED X-RAY AND LASER PROJECTION DEVICE

TECHNICAL FIELD

This invention relates to a combined fiuoroscopy and laser projection device for exact location and superficial display of a complex x-rayed structure, outlined, highlighted or pinpointed by the user of the present invention.

BACKGROUND OF THE INVENTION

Combined X-Rav and Laser Projection Device State-of-the-art in the surgical field increasingly utilizes minimal invasive procedures. Utilizing modern computer technology, an unknown grade of accuracy has been achieved for preoperative planing and image guided surgery. These new methods belong to the field of Computer Assisted Surgery. Current applications include "Robodoc", a system which prepares the proximal femur for the shaft of a total hip replacement with submilhmeter accuracy, and navigation system which allows a secure insertion of pedicle screws in spine surgery. In both examples, an extensive collection of a patient's image data in the form of a CT or MRI is the basis for the preoperative planning. Special equipment has to be installed in the operation room. For some applications, the relation between the necessary efforts (time, equipment) and the real benefits is not always in favor of these new hi-tech systems. Although fiuoroscopy devices with laser diodes mounted on C-arms already exist, the main function of these is the alignment of the C-arm towards the object to focus on the region on interest. Also, they have limited possibilities due to a fixed or manually operated laser beam. German patent no. DE 40 03 350 C describes a device to help position a lithotripsy apparatus and aim the lithotripsy shock wave to the kidney stone for example. The laser beam of the device therein is manually positioned to the iso- center of the C-arm's image field. The radiation dose increases because commonly more than one attempt is necessary to center the laser beam. During fiuoroscopy there is the problem of localizing the x-rayed anatomical structures in comparison with the patient's body surface. Especially small structures like aneurysms, screws, bullet fragments, etc., can be difficult to find during an operation. Also, for minimally invasive procedures, the patient's skin obstructs the surgeon's direct view on the target object. Thus, the position of x-rayed structures cannot be directly placed in relation to the actual operation situs.

SUMMARY OF THE INVENTION

This invention provides an apparatus for fiuoroscopic imaging and projection of an x-rayed structure. This apparatus comprises an x-ray source and an image intensifier mounted on a common support. A range finder associated with the image intensifier determines distance from the image intensifier to an object being x-rayed. A computer receives data from the image intensifier and processes this data. A screen associated with the computer permits display of an x-ray image. Through interfacing with the computer, the user then pinpoints, highlights or outlines the structure or other anatomy being examined, as desired, A projector (e.g., a laser projector) receives data corresponding to the outline, highlight or pinpoint delineated by the user, from the computer and projects a visual image (e.g., a laser image), onto the skin of the patient at the location of the x-rayed structure or anatomy.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings: Fig. 1 is a schematic representation of a combined x-ray and laser projection apparatus according to this invention.

Fig. 2 is a schematic representation of the apparatus of Fig. 1, positioned for x- ray imaging of a human patient.

Fig. 3 is a schematic representation of the apparatus of Fig. 1, positioned for display of selected structures of the patient.

Fig. 4 is a diagrammatic elevational view of an x-ray source which forms part of the apparatus of Fig. 1.

Fig. 5 is a front view of the x-ray source shown in Fig. 4. Fig. 6 is a back view of the x-ray apparatus shown in Fig. 5. Fig. 7 is a schematic view of a computer system used in the practice of this invention. Fig. 8 is a block diagram of a computer system illustrating the practice of this invention.

Fig. 9 is a illustration of the projected image size depending on angle alpha. DETAILED DESCRIPTION This invention will now be described in detail with particular reference to preferred embodiments.

Figs. 1-9 illustrate the apparatus of this invention.

Referring now specifically to Fig. 1, a combined x-ray and laser projection apparatus 20 according to this invention comprises an x-ray source assembly 30 and an image intensifier 40, both mounted on a suitable support structure 50. Throughout this application applicant uses the terms x-ray and fiuoroscopy interchangeably, as it is known in the art to denote electronic capture and projection of an image obtained by x-ray radiation. A preferred support structure is portable and comprises a C-arm 52 clamped to a portable cart 54 which is on wheels so that it can be moved from place to place. The device further comprises a computer system which is capable of processing x-ray imaging data and user input data in real time and displaying in real time an x-ray image on a screen or monitor, and a two-dimensional visible image or outline (e.g., a laser image) delineating an area under study or investigation.

The x-ray source assembly 30 and the image intensifier 40 is not part of the present invention and may be one of many conventional designs. Most commonly, the x-ray source assembly 30 and image intensifier 40 are housed in cylindrical housings which are coaxially mounted at opposite ends of a C-arm 52, as may be seen in any of Figs. 1-3. For illustration purposes only, and as shown in Figs. 1-3, the x- ray source assembly 30 may be mounted on the lower end of the C-arm 52 and the image intensifier 40 may be mounted on the upper end of the C-arm 52. The C-arm 52 and the cart 54 to which it is secured may be conventional, and the C-arm may have an arcuate center axis (not shown) which is in a vertical plane and extends through an arc of about 180°. The structure of x-ray source assembly 30 is shown in further detail in Figs. 4-6. As may be seen therein, the x-ray source assembly 30 may have a cylindrical housing 32 which includes upper and lower end walls (which may be denoted as a front wall and a back wall, respectively) in addition to a cylindrical side wall. Inside this housing are an x-ray source or tube 34. A laser beam source 36, and a range finder 38 of the present invention may be placed within the assembly 30 or about the housing of the assembly. Optionally, the laser source 36 and the range finder 38 of the present invention may be affixed about a support separate from the c-arm of the x-ray apparatus. An x-ray beam 34a emanating from the x-ray source 34 is directed upwardly along a vertical axis (see Figs. 2 and 4; the dot-dash line in Fig. 4 denotes the axis) through an aperture in the upper wall of the housing (see Fig. 5). The x-ray beam is conical and has a small vertex angle (which is greatly exaggerated in Fig. 2), as is conventional. The x-ray beam is received by image intensifier 40, and is processed as will be described later.

The x-ray assembly 30 may also include a joint 39 which allows the assembly 30 to be rotated 180° so that the laser beam 36a and the range finder beam 38a project upwardly and the x-ray beam 34a projects downwardly. Optionally, the range finder 48 and the laser projector 46 may be affixed about the housing of the x-ray source and image intensifier, so that there is no need to rotate these elements.

An image intensifier 40 is mounted at the upper end of the C-arm 52, in axial alignment with the x-ray source assembly 30, so as to receive an x-ray beam emitted from the x-ray source, as is known in the art. This may be seen in Figs. 1-3. As shown in Figs. 1-3, image intensifier 40 comprises a housing, which may be cylindrical and may comprise a cylindrical side wall and upper and lower end walls. The lower end wall may be a front wall and the upper end wall may be a rear wall. Inside the image intensifier housing are an x-ray receiving element, a laser beam source (or laser beam projector) 46 and a range finder 48. Optionally, laser beam source 46 and range finder 48 are affixed about the housing of image intensifier 40. This allows the present invention to be retrofitted onto an existing x-ray apparatus.

The x-ray receiving element may receive radiation through an aperture in the lower or front wall. The laser beam source 46 and the range fmder 48 emit beams through apertures in the upper or back wall. The axes of the laser beam source 46 and the range finder 48 are as close together as possible and nearly parallel (they may be slightly convergent), and are different from (preferably 180° opposite from) the axes of the x-ray receiving element. This may be seen in Figs. 1-3. The laser unit 46 emits a pencil-thin collimated beam 46a of visible light along a downwardly extending vertical axis through an aperture in the lower or back wall of the housing (see Fib. 6). The beam is slightly conical but has a very small vertex angle as is conventional. A preferred laser source is a diode pumped, frequency doubled Nd: YAG laser, with laser output power of 20 mW and a wave length of 532 nanometers (ran) so that it appears red. Its laser safety classification is Illb. However it should be noted that other lasers with similar characteristics can be used with the present invention.

The range fmder 48 may be either a laser or ultrasound unit with the laser range finder being slightly more preferred. Presently, a laser range finder having a wavelength of 650 ran, laser class II is utilized with the present invention. The range fmder directs a beam 48a of wave energy downwardly through an aperture in the bottom wall of the x-ray assembly housing (see Fig. 6).

The laser unit 46 and the range finder 48 are placed as close together as possible for the sake of precision. However, the computer associated with the present invention may perform calculations to compensate if laser unit 46 and range finder 48 are separated by greater distances. In the present preferred embodiment, the respective beams are essentially parallel in that they are actually slightly convergent and lie in a common vertical plane. The laser system of the present invention comprises the laser range fmder 48, a laser projector 46, a laser scanner control board and a laser PC card which are programmed to project an image created by the user through interfacing with the computer system. The software addresses the PC card to divert the laser projected by the laser projector 46 to a certain angle. The PC card transforms the digital data into analog voltage data which is sent to the laser scanner control board. The laser scanner control board changes the angles of the mirrors of the laser scanner projector 46 by directly addressing the scanner motors. To simplify the laser control, the laser system of the present invention may incorporate a virtual coordinate system ranging from - 32768 to 32768 pixels in both the x and y axis. Presently the electronics used in association with the present invention include a PENTIUM or equivalent, IBM PC or equivalent; a Matrox Meteor II video capture card having a PCI bus and monochrome image acquisition; Two Cambridge Technologies CT 6800 HP laser scanners for x and y laser beam diversion; A diode pumped, frequency doubled Nd: YAG laser having laser safety class Illb, laser output power of 20 mW, and a wavelength of 532 ran; A LASERGRAPH II Pc Laser I/O card for Analog-Digital/Digital- Analog conversion having a 16 bit ISA bus, manufactured by hb-Laserkomponenten in Germany; and a laser range fmder having an optoelectronic sensor with reflection time measurement which emits a brief laser pulse and measures the time required for the laser light to be reflected back from the targeted object, having a laser safety class II laser and a wavelength of 650 ran. However, it should be noted that equivalent devices could be substituted without affecting the scope or intent of the present application.

As illustrated in Fig. 9, using trigonometric calculations, the projected image height can be calculated using the laser diversion angle alpha and the measured distance d. The calculation used is

Tan alpha = Image Height (h in mm) / Distance (d in mm). The laser system's virtual coordinate system can be addressed to define the number of laser pixels to be projected by the laser scanner projector 46. This means that for every angle alpha, a correlating laser pixel number exists. Each angle alpha and pixel number are independent from the measured distance (d). The first step is to project a known number of laser pixel (LP) and to measure the distance (d) and image height (h).

(a) Tan alpha_Lp = LP/h

(b) Image height (h) = Tan alpha_Lp

(c) K with K= LP / Tan alpha_Lp is constant

To calculate the number of laser pixels (n) to project an image of defined size(s) at a given distance (d) the following formula is used: n [lp] = (s [in mm] * K [lp] / d [in mm] = s [in mm] * (LP [lp] / Tan alpha_Lp ) / d [in mm].

Figs. 2 and 3 illustrate how a patient may be interposed between an x-ray source assembly 30 and an image intensifier 40. By way of example and illustration of the characteristics and capabilities of the present invention only, Figs. 2 and 3 relate particularly to use of the apparatus of this invention in a surgical procedure for the repair of a broken femur in a human patient. However, other uses and applications of the apparatus of this invention will be discussed below, and it will be apparent that this apparatus has widespread applicability in a number of medical and surgical fields and for contemplated non-medical purposes as well.

With the imaging intensifier 40 in the position shown in Fig. 2, x-ray radiation emanating from x-ray source 34 in x-ray source assembly 30 passes through a selected target area or portion of the patient. This selected target area includes a subsurface structure to be x-rayed, namely by way of example, a broken femur. The resulting x-ray image is received by imaging intensifier 40, which intensifies the image and transmits it to a computer system for display and further processing. A preferred computer system 60 forming part of the present invention is shown in Figs. 7 and 8; Fig. 7 illustrates representative computer hardware. Operational aspects of the apparatus of this invention are shown in Fig. 8.

Referring to Fig. 7, the hardware of a computer system 60 for use in the present invention is shown. The system 60 includes a video capture card 62 for receiving or capturing a fiuoroscopy image transmitted from image intensifier 40, and a computer screen or monitor 64 on which a fluoroscopic image may be displayed. The system may further include either a keyboard 65 or a mouse 66 for manual user data input. Further, the system 60 may include a housing 68, which may be behind the screen 64, for housing additional electronics. The computer hardware is a conventional PENTIUM or equivalent IBM (PC), IBM compatible, or APPLE. The hardware may be conventional. However, the computer system 60 herein is programmed in such manner as to achieve unique results as will be described subsequently.

The computer screen 64 is illustrated as being in physical proximity with the keyboard 65. However, the screen may be placed in any location where a user, e.g., a surgeon, can see the images displayed on the screen which he of she is using the device of this invention.

Fig. 8 further illustrates a computer 60 for the present invention. The computer may include application software which may be designed for use with various applications or specifically for one intended application (repair of a broken femur, for example), a video capture card 62 (or frame grabber card), and an analog- to-digital/digital-to-analog (AD/DA) converter card. Input data for the computer include an intensified x-ray image (which may include an image of a marker of known dimension which has been placed in the x-ray image field), obtained from image intensifier 40; range finder data, indicative of the distance from the image intensifier 40 to the patient, also obtained from image intensifier 40, and user input data, which can be manually entered by a user using keyboard 65 or mouse 66. The computer 60 processes this input data and forms output data which is transmitted to the image intensifier 40. The laser unit 46 associated in the image intensifier 40 projects onto the patient's surface (or skin) a laser image created by the physician or technician, through use of the present invention, to pinpoint, outline or highlight the anatomy or target sight displayed by the imaging apparatus, i.e. the fiuoroscopy apparatus. This image is formed on the surface just in front of the subsurface structure which is being x-rayed.

Also illustrated in Fig. 8, is the software utilized with the present invention, which allows the physician or other user to project points, lines and/or other laser images which he or she has drawn in free-hand, prior to commencing the procedure. The software processes the image generated by the x-ray apparatus and captured by the video capture card 62 and allows the image to be displayed on a video monitor or screen. The software then allows the user to pinpoint, highlight or outline portions of the anatomy displayed in the fiuoroscopy image through interfacing with the computer through a keyboard, mouse or other input device. After receiving data from the range finder 48 on the distance the patient is from the laser projector 46, the software transmits the data inputted by the user and interacts with AD/DA converter card. The AD/DA converter card transmits this data to the laser projector 46 which in turn projects the pinpoint, highlight or outline drawn by the user through the computer.

Operation

Operation of the apparatus or device of the present invention will be described with reference to specific applications. The procedures described herein are by way of example since the present invention is useful generally in medical diagnostic and treatment procedures in which a subsurface structure of a patient is imaged. The first of these, by way of illustration, will be a surgical operation to repair a broken bone of a human patient by installation of a plate (minimally invasive plate osteosynthesis). A patient is first anesthetized or otherwise immobilized in order to initiate the x-ray image. It is important that the patient remain immobilized during the entire procedure, in order than the image taken by the x-ray apparatus and viewed by the user, remains in constant alignment. If the patient moves during the course of the procedure, it will be necessary to obtain another x-ray image.

A patient with a broken bone placed on a radiolucent operating table, is positioned as shown in Figs.2 and 3, so that the thigh portion of the patient's body, lies at the center of a C-arm 52 and in a straight-line path between an x-ray source assembly 30 mounted at the bottom of the C-arm and an image intensifier 40. Both the x-ray source assembly 30 and the image intensifier 40 are oriented as shown in Fig. 2, with the x-ray tube 34 in the x-ray source assembly 30 facing upward so as to emit an upward x-ray beam 34a, and with the x-ray capture unit 44 in the image intensifier 40 oriented downwardly to capture the x-ray image formed as the x-ray beam passes through the thigh portion of the patient's body so as to image the broken femur (the x-rayed structure).

An object or marker of known size, such as a coin of known diameter or a rodlike marker of known length, is placed in the field of the x-ray beam, preferably on the body of the patient, to enable a user to calibrate the system in order to calculate the size of x-rayed objects.

A fiuoroscopy (or x-ray) image is then taken, with the x-ray assembly 34 and the image intensifier oriented as shown in Fig. 2. The resulting image, which shows both the x-rayed structure or object (e.g. the broken femur) and the marker of known dimension, is collected and intensified by the image intensifier 40. This image is transmitted to the computer 60 and is displayed on screen 62. Image distortion is corrected with computer software.

Introspective planning is possible with the angle/measurement functions of the software. This is important for instrument alignment during osteotomies, for example.

After a fluoroscopic (or x-ray) image has been obtained, corrected to remove distortion, and displayed on the computer screen 62 as described above, the user (e.g., the surgeon or a person assisting the surgeon) turns the image intensifier 40 around so that its laser unit 46 and range finder 48 are directed toward the patient. This may be done via joint connectors 39 and 49 or by other means. However, if the laser source 46 and range finder 48 are fixed about the housing of the image intensifier 40, no rotation about joints 39 or 49 is required.

Utilizing the computer software, the user can pinpoint, highlight, or outline the structure (or structures), with the corresponding laser image of this pinpoint, highlight or outline being projected onto the patient by the laser projector. The physician may use the present invention to pinpoint, highlight or outline structures such as bones, vessels containing contrast fluids, metal plates and screws, or other x-rayed structures - in fact, any subsurface structure which has been imaged earlier. The principles of the software utilized are similar to those of "Head-up Displays" used on fighter airplanes to achieve accurate targeting.

After the present invention has been calibrated through imaging of an object of known size, the x-rayed structures delineated as the laser image projected by laser projector 46 will be of the same size as the original x-rayed structures. In addition, these laser images will be projected onto the portion of the patient's body which directly overlies the x-rayed subsurface structure. Thus, in the case of a patient with a broken femur, the user may outline, highlight or pinpoint, dimensional and spatial characteristics of the fracture or other localization, and project these pinpoints, highlights or outlines, drawn by the user, onto the thigh region of the patient directly over the actual broken femur. This allows the user to more quickly orient himself to the location of the fracture or other anatomy being viewed. This also allows the user to better determine the correct placement of corrective or supportive devices or implants, and align medical instruments during the surgical procedure. Furthermore, if it was desired isolate or stay away from certain anatomy during a procedure, use of the present invention would enable a user to outline, highlight or pinpoint this anatomy, without having to surgically determine its location.

The user may then optionally paint lines corresponding to the imaged structures onto the patient's body using a marker pen. A plate implant of correct size can be selected using the software's intraoperative planning and measurement functions. Previously stored images of different implants can be loaded into the computer program to test the fit without opening packages containing a sterilized implant for that purpose. The plate can be positioned over the fracture area. Now another fiuoroscopy image is taken. The plate can now be projected onto the patient's surface. The holes for incisions are marked with a pen, small incisions are made at the marked hole locations, and screws of appropriate length are inserted. The screw length has been measured with the computer software. The angle/measurement functions of the computer software makes it possible to align instruments (a drill, for example) along the laser beam, so that drilling and insertion of screws at the correct angle are achieved. While Figs. 1 and 2 show treatment of a patient's thigh region, it will be apparent that the minimally invasive plate osteosynthesis procedure set forth herein can be used to repair a broken bone in any portion of the body where installation of a plate is appropriate.

Also by way of example, another procedure which can be carried out according to this invention is the installation of nail locking screws. A device that is being increasingly widely used in femoral and fibial fractures is a Grosse-Kempf intramedullary nail (which is a tubular metal structure with a single slit down its longitudinal axis). This nail is held in place by transverse nails or locking screws. Incisions for the screws or nails may be made by drilling holes along axes which are precisely aligned with the transverse nail hole axes in the intramedullary nail. U.K. Patent Application GB 2 280 343 A briefly describes this procedure and uses a point laser beam to define the path of the drill. For a minimally invasive approach, the present invention projects the holes and entry points onto the patient's skin, and indicates the correct angle for drilling. For screw ostosynthesis or removal, one can localize the implants on an x-ray image and project an image of the implants onto the patient via laser projection. Small incisions can then be made for screw insertion or removal.

For K-wire osteosynthesis the trajectory of the K-wire to be drilled can be displayed on the patient before the actual procedure to allow exact alignment of the drilling machine.

This invention has been described so far with particular reference to surgical procedures on broken bones in human patients. Other subsurface structures of a human patient which can be displayed in accordance with this invention include organs, blood vessels, and foreign bodies, for example. Procedures in which such structures are displayed as landmarks include, for example, osteotomies, spine surgery, tumor removal, foreign body removal, surgeries (e.g., neurosurgery, vascular surgery and heart surgery) requiring localization of vascular anomalies after contrast fluid injection.

While the object being x-rayed is ordinarily a human patient or portion thereof, (i.e., a portion such as a head, a thigh, etc., which includes a subsurface structure, such as a bone, an organ, or a blood vessel, which is in need of treatment), the object may be a non-human vertebrate animal (e.g., bird or a mammal).

Advantages

The present invention enables a user to localize x-rayed structures beneath a patient's body surface by projecting them onto the latter without taking multiple trials using instruments to correlate the position on the x-ray image with real-world coordinates. In this way, the user can virtually "look through the patient's skin" and gain enormous additional information at no extra radiation cost. Simple geometric forms and also complex forms identical to the x-rayed objects can be projected on the patient. Intraoperative planning is achieved with implemented angle and length measurement functions in the software. Immediate execution is made possible by aligning instruments along a laser beam.

This invention reduces operating time, increases accuracy and reduces exposure of patients and medical personnel to x-radiation.

While this invention has been described in detail with reference to preferred embodiments thereof, it will be apparent that variations and modifications can be made by those skilled in the art. Accordingly, the scope of this invention shall not be limited except by the scope of the appended claims.

Claims

What is Claimed Is:

1. An apparatus, used in conjunction with a fluoroscopic imaging device, for locating a target site below the skin of a patient comprising: a laser projector device, mounted at a predetermined position relative to the patient, for adjustably projecting at least one laser image; a range finder, mounted at a predetermined position relative to the patient and to the laser, for determining a distance between said laser scanner device and the patient; a computer for receiving and processing data from the fluoroscopic imaging device and from said range finder; a screen for displaying an image from the fluoroscopic imaging device; a highlighting device operatively interfacing with said computer for highlighting one or more target sites within the displayed image; said laser projector device receives data from said highlighting device to position one or more lasers within said laser projector device to generate a laser image on the surface of the patient, said laser image identifying the location of the target site.

2. An apparatus for fluoroscopic imaging and location of a subcutaneous structure within a patient comprising: a device for generating a fluoroscopic image; a laser projector device, mounted at a predetermined position relative to the patient, for adjustably projecting at least one laser image; a range fmder, mounted at a predetermined position relative to the patient and to the laser, for determining a distance between said laser scanner device and the patient; a computer for receiving and processing data from the fluoroscopic imaging device and from said range finder; a screen for displaying an image from the fluoroscopic imaging device; a highlighting device operatively interfacing with said computer for highlighting one or more target sites within the displayed image; said laser projector device receives data from said highlighting device to position one or more lasers within said laser projector device to generate a laser image on the surface of the patient, said laser image identifying the location of the target site.

3. An apparatus according to either of claims 1 or 2, wherein said laser image further simulates characteristics of the target site.

4. An apparatus according to any one of claims 1, 2 or 3 wherein said laser image simulates one or more dimensions of the target site.

5. An apparatus according to any one of claims 1-4, wherein said laser projector device comprises a laser scanner.

6. An apparatus according to any one of claims 1-4 wherein said laser image is a point, a line, a geometric pattern or a free-hand structure.

7. An apparatus according to any one of claims 1-4 wherein said laser projector device is fixed relative to the fluoroscopic imaging device.

8. An apparatus according to any one of claims 1-4 wherein said range fmder is fixed relative to the fluoroscopic imaging device.

9. An apparatus according to any one of claims 1-4 wherein said range finder is laser based.

10. An apparatus according to any one of claims 1-4 wherein said range finder is ultrasonic based.

11. An apparatus according to any one of claims 1-4 wherein said computer includes a video capture card.

12. An apparatus according to any one of claims 1-4 wherein said computer includes stored electronic template images of implants to be used at said target site.

13. An apparatus according to any one of claims 1-4 further comprising a marker associated with the patient which can be imaged and use for calibration of dimensions within the fluoroscopic image.

14. A method of determining the location of a target site below the surface of the skin of a patient comprising the steps of: (a) generating an image of the patient's anatomy; (b) electronically capturing said image; (c) displaying said image on a monitor: (d) using a highlighting device operatively interfacing with a computer for highlighting one or more target sites within the displayed image; (e) transmitting data from said highlighting device to a laser scanner device which positions one or more lasers within said laser scanner device; (f) generating one or more laser images on the surface of the patient, said laser image identifying the location of the target site below the surface of the skin of the patient.

15. A method according to claim 14 further comprising the step of: utilizing a marker associated with the patient which can be imaged and use for calibration of dimensions within the fluoroscopic image.