 |
Description  |
|
|
The present invention relates to an instrument for use in guiding and
directing a tool such as a biopsy needle along a predetermined path, and
more specifically relates to apparatus for projecting a light beam to
define the path to guide the tool, e.g., to guide a biopsy needle to the
lesion.
BACKGROUND OF THE INVENTION
The present invention will be described in connection with its preferred
use, and that is to guide a biopsy needle during its insertion into human
tissue to reach a lesion such as in a breast. The invention is not limited
to this one use as it may be used in other instances, e.g., the X-ray of a
fractured bone and provision of a locating and guiding beam to guide the
proper angularity of a screw being threaded into the bone at a precise
location and angle to secure bone fragments or a prothesis in a proper
position.
In recent years the public has become very aware of the importance of X-ray
examination of women's breasts in the control and cure of breast cancer.
The early detection of cancerous tumors is recognized as significantly
improving the chances of successful treatment. As a consequence, women of
a certain age or genealogical background are subject to X-ray examination
of their breasts at frequent intervals. Such examination often detects
tumors or lesions which are of a questionable character, it being
impossible to determine from the X-ray whether the tumor or lesion is
malignant or benign. In such situations, it is normal to take a specimen
or biopsy of the tumor or lesion to permit a careful examination of the
abnormal tissue.
The most common means of taking a biopsy of a tumor or lesion in a woman's
breast is a stereostatic device which uses an elongated needle which may
be inserted with a rotary movement to cut a core sample of tissue in the
area of the tumor or lesion. The needle is equipped with suction means to
aid in extracting the cylindrical section of tissue. Since the current
trend is toward early detection through frequent examination, the tumor or
lesion which is to be checked through the biopsy is often very small and
barely discernable on the X-ray. With the tumor or lesion often being well
below the skin surface, it is extremely difficult to insert the biopsy
needle with sufficient accuracy to engage and sample the area of tissue
that is of interest and requires further testing.
In the presently used procedure, the breast of the patient is compressed
against a horizontal surface below which the X-ray film is positioned. The
compressing member is placed above the breast, clamping it against the
surface, leaving a panel of skin exposed through a rectangular opening
which has indicia on the sides of the opening to aid in establishing the
location of the tumor discovered on the X-ray. By establishing the
coordinates of the location of the tumor from the X-ray, a mark is placed
on the location on the exposed skin using the indicia beside the opening
to show where the biopsy needle should be inserted. An additional X-ray is
taken to show the depth of the tumor so that the needle may be inserted
and the specimen taken at the proper depth below the skin surface. After a
biopsy specimen has been taken, another X-ray is taken to assure that the
biopsy specimen is from the suspected tissue.
Because of the limited size of the tissue to be sampled and the possible
errors in correlating the location of the needle insertion with the
location of the tumor as shown on the X-ray, it is not unusual for many
needle insertions to be required before achieving the proper location of
the needle with respect to the tumor. The procedure causes considerable
pain and discomfort and the prolongation resulting from the techniques
employed suggest that improved techniques are required.
One attempt at locating the biopsy needle more precisely with respect to an
X-ray picture of a tumor has involved the use of movable cross wires to
create a shadow produced by an incandescent lamp to locate the needle
insertion point on the skin. This technique has not proven to be
particularly helpful, since the shadow image of the wires was not sharp
enough to give a precise location and the normal ambient light in the area
was usually too high to permit good visibility of the shadow image of the
wires.
Another approach involved use of a laser dot which was projected in from
the side to spot the needle insertion location on the skin. The angle at
which the laser beam was projected tended to introduce errors since any
deflection of the skin would cause the laser spot to shift location.
Another problem associated with biopsy is the difficulty of inserting and
guiding the needle at the correct angle so that the needle tip is not
displaced to a side of the tumor when the needle is inserted to the proper
depth. The coordinates of the position of the tumor are determined from an
X-ray beam that is usually located twenty inches or so above the X-ray
film located beneath the breast. Herein, the X-ray beam emanates from an
X-ray source that may be considered a point source because the X-ray beam
that expands in size as it travels to X-ray film. At one particular
location, e.g., usually at a coordinate designated D-5, the X-ray beam is
directly vertical over the coordinate and the beam is perpendicular to the
underlying X-ray film. A tumor located at D-5 will be hit by a needle
located at the D-5 coordinate and guided perpendicular to the film and
along a true vertical line. In such a system, when a breast tumor is
located at the rear corners of the opening in the paddle, the X-ray beam
from the point source may be at an angle of 3.degree. to 5.degree. with
respect to the vertical. If the needle tip is inserted only along a true
vertical plane, there is a chance that the needle tip may be displaced at
an angle from the tumor missing the tumor, and this may necessitate the
taking of another sample. Needless to say, such misses can be painful; and
the uncomfortable position of the patient may be needed to be maintained
considerably longer than necessary if the angle of needle insertion had
been the same as the angle of X-ray beam. The lesions can be very small so
that the missing of the lesion can occur quite easily.
In the aforesaid patent application, a continuous mark in the form of a
cross or cross hair was generated from a unit located about six inches
away from the X-ray point source. While the instrument disclosed in this
application was a vast improvement over the conventional equipment, and
has been used satisfactorily, the present invention is directed to the
elimination of parallax that might be present in such devices. That is,
the present invention eliminates the difference in apparent direction of
the tumor, as seen from the X-ray point source on the one hand, and the
laser source for the cross hair mark on the other hand. More specifically,
the laser source is moved to eliminate parallax and to guide the needle
along the angle and to the position of the tumor to assure that the needle
is inserted at the same angle as the X-ray beam from the X-ray point
source. Thus, when a second X-ray is taken, it should verify that the
biopsy sample is taken from the tumor previously located for sampling.
SUMMARY OF THE INVENTION
The present invention involves method and apparatus for guiding a tool or
member such as a biopsy needle into tissue or a screw into a bone along a
predetermined angular path and/or to a specific location that was
previously located by an X-ray of tissue or bone. The present invention,
although not limited to the specific use of obtaining a biopsy specimen,
is described herein in connection with the obtaining of a biopsy specimen
after having identified a tumor or lesion through X-ray examination. The
X-ray machine in connection with which the invention is used has an X-ray
head supported above a specimen supporting platform with means provided to
immobilize or clamp the specimen to be examined, as for example a woman's
breast, against the platform. An X-ray film is disposed on the platform so
that the X-rays radiated from the X-ray head pass through the specimen and
provide an image of the specimen on the film. When a possible cancerous
tumor or lesion is noted in the X-ray, it often becomes desirable to take
a biopsy for further testing to ascertain the nature of the tumor. In
order to take the biopsy, it is necessary to identify on the patient's
skin exactly where the biopsy needle should be inserted to engage the
tumor or lesion observed on the X-ray.
In the method and apparatus of the present invention, a light source
generates a light beam at a controlled angle to guide the tool along a
path coincident with the path of the radiated X-ray beam from the X-ray
source through the lesion and to the underlying X-ray film. The preferred
light source comprises a pair of laser sources which are detachably
mounted between the X-ray head and the specimen platform to provide two
aligned intersecting laser beams that are directed along the same common
axis as the radiated X-rays. The laser beams are focused to be visible on
the surface of the X-rayed specimen as a pair of lines which intersect at
90.degree. to each other. The laser sources are mounted on a carriage
which is movable along one path parallel to one of the lines and along
another path parallel to the other line. Thus, by moving the carriage
along either of two mutually perpendicular paths, the location of the
intersection of the lines formed by the laser beams may be moved to any
desired location. The clamping means or plate, which overlies the specimen
platform and clamps the specimen, is formed with a rectangular opening in
which a portion of the specimen is exposed. The specimen is disposed so
that the tumor or lesion to be biopsied lies under the skin which is
exposed through the opening in the clamping means. In order to insert the
biopsy needle accurately, it is necessary to provide a marking or
indication on the exposed skin as to where the biopsy needle should be
inserted to engage the tumor or lesion indicated by the X-ray. A scale is
used to establish the coordinates of the tumor location in the clamping
means opening. These coordinates are then used to position the laser beam
lines intersecting at the location on the skin above the tumor.
The laser beams are generated by diode lasers generating an oval dot which
is directed through a cylindrical lens to expand the beam to form a line
which is reflected from a mirror onto the specimen. The beams as they are
directed toward the specimen are substantially coaxial, appearing to
emanate from a single source. The laser source closest to the specimen is
reflected by a beam splitter which only reflects 50% of the impinging
beam. The beam from the laser source more remote from the specimen is
first reflect by a mirror and that beam is directed through the beam
splitter toward the specimen, with 50% of the beam passing directly
through the beam splitter and to the specimen and 50% being reflected.
This results in the two beams being coaxial and intersecting as they pass
from the beam splitter to the specimen. Preferably, the laser head
containing the two laser sources is detachably mounted directly in line
with the X-ray head so that the laser beams engage the specimen along the
same general path as the X-rays.
One problem in using laser beams to target or locate a position on the skin
for inserting a biopsy needle is the fact that the laser beams may reflect
from the clamping means into the eyes of the person using the instrument
or the patient on whom it is being used. Accordingly, the laser beams may
be provided with compensation means that redirects the beams as the laser
supporting carriage is traversed so that the locating lines on the
specimen remain on the exposed portion of the skin within the opening in
the clamping means. Cams are provided so that as the carriage traverses in
either of the two orthogonal directions, the mirror and the beam splitter
are adjusted to maintain the centering of the laser lines within the
opening in the clamping means.
The elements of the laser sources, including the diode lasers and the
lenses as well as the mirror and beam splitter, are all mounted in a
single Delrin block which forms the major portion of the movable carriage.
The block provides a vibration-free and dimensionally precise means of
mounting the laser sources and the adjustable mirror and beam splitter.
Drilled pockets receive the diode lasers and the cylindrical lenses.
Drilled holes are provided to receive axles that pivot the mirror and beam
splitter and to receive guide rods for mounting the block for transverse
movement.
The carriage providing the movable mounting for the laser sources includes
an inverted U-shaped frame mounted for what will be termed front-to-back
movement. The carriage frame supports the Delrin block for left/right
movement with respect to the frame. Reversible motors are provided to
drive the block with respect to the carriage and the carriage with respect
to the laser head to position the laser sources and the laser beam lines
with respect to the specimen or the opening in the clamping means.
The visible lines produced by the laser beams on the skin of the specimen
are focused to have a width of 0.020 inches located about 18 inches from
the laser source. Under the typical clamping pressure of about 30 pounds,
the breast of the patient would typically space the clamping means from 1
to 3 inches from the supporting platform. The flesh of the specimen tends
to bulge upwardly through the opening in the clamping means, making it
difficult to fix the location on the skin with the coordinate location of
the tumor or lesion as obtained from the X-ray. However, the laser beam
line extends to a point adjacent the indicia on the edge of the opening,
facilitating the alignment of the laser beam lines with the proper
coordinate location.
Once the laser beam lines have been properly located by movement of the
carriage with the motor drives, the intersection of the lines is used as
the location for inserting the biopsy needle into the skin. Since the
needle is about 0.090 inches in diameter, an incision is normally made
before inserting the needle. The needle is connected to a source of
suction to withdraw a cylindrical core or sample. The angled end of the
needle is sharpened but must be rotated as it is inserted to cut the
specimen to be removed. It is difficult to maintain the needle at a
desired angle as it is inserted while rotating at the same time. Any
deviation from this desired angle tends to introduce an error, since the
insertion location is predicated on going downwardly to the tumor or
lesion location at the desired angle.
A problem like that of parallax arises because the X-ray source is located
in the X-ray head located above the laser head unit, which is attached to
the bottom of the X-ray head. The X-ray source generally is a point source
that generates an X-ray beam that is controlled by a diaphragm in the
X-ray head. For example, a rectangular beam pattern, with a portion of the
X-ray beam is directed straight downwardly at one coordinate position,
e.g., C-1 and with the other portions of the X-ray beam at different
coordinates having an inclination relative to the vertical. At the
farthest locations from D-5, which are at coordinates A-1 and A-9 in this
instance, the angle has the greatest inclination to the vertical. Thus, a
lesion at a coordinate position A-1 or A-9 will be on a line drawn from
the X-ray source to the film which line is at an angle to the vertical.
The laser head on the other hand travels to a coordinate position directly
over the lesion and directs a true vertical light beam down onto the skin
at the coordinate position where the incision is to be made and provides a
continuous guiding light on which the needle is centered when it is
inserted. At the D-5 coordinate position, both the X-ray beam through the
lesion and light beam are coincident; but at other coordinates, such as
A-9, the X-ray beam through the lesion may be at 3.degree. or more to the
vertical and the laser light beam should no longer be vertical, as the tip
moving into the breast may miss a small lesion or is not at spot desired
because of these different angularities. This is or is akin to a parallax
error.
In accordance with the present invention, the problem of parallax is
eliminated by aligning the light beam with the X-ray beam at a
predetermined location or coordinate position and then having a shifting
means which shifts the light beam as though it emanates from a point along
the path that the X-ray beam took through the lesion. In the preferred
embodiment, the X-ray beam and light source are calibrated initially at a
selected coordinate position, e.g., D-5 by having the X-ray beam go
vertically through a calibration opening in a calibration plate and
adjusting the light source and thereby the light beam until it is vertical
and shines through the calibration opening in the calibration plate while
the laser head is at the same D-5 coordinate position. The greatest
angularity from a D-5 position for the X-ray is at the rear corners of the
window in the paddle. The light beam is shifted by either rotating the
mirrors, or the light source is shifted by cams so that the light beams
are along a path from the X-ray point source through the lesion to the
X-ray film. Thus, when one guides the tool such as a biopsy needle along
this angle with the cross hairs centered on the upper end of the needle,
the needle will travel into the flesh at the same angle as the X-ray beam
traveled through the flesh and lesion to reach the film. Thus, the needle
tip should be within the lesion when inserted to the proper depth.
The preferred light source for generating the visible guiding and locating
beam is movable within the device to a position out of the path of the
X-ray beam so that the X-ray beam may be shot through the openings in the
device to take an X-ray to assure that the biopsy being taken is at the
lesion. Preferably, the light source is driven to a home position such as
a zero coordinate position, and a safety switch is actuated by the light
source to assure that it is home when the X-ray source is actuated.
Thus, it will be seen that the nature of the laser beam is such that it
provides a sharp, well defined line of light at the surface of the
specimen and also at a level 10 inches above where the upper end of the
biopsy needle terminates. It is therefore possible to use this extended
intersection of the laser beams to establish a line along which the biopsy
needle must move to properly engage the tumor. After the tip of the needle
is located and engaged with the skin, the intersection of the laser beam
lines is positioned on the outer end of the needle in an axially aligned
location to assure that the needle remains at the controlled angle as it
is rotated and forced downwardly into the specimen. As long as the axis of
the needle is maintained centered on the intersecting beams, the
controlled angularity of the needle will be maintained. The fact that the
intersection of the beam emanates along the line of the X-ray radiation
assures that the biopsy needle will be inserted accurately at the surface
of the specimen and will move inwardly to engage the tumor or lesion. As
long as the coordinates or the tumor are taken accurately from the X-ray
image, the apparatus and method of the present invention provides a
completely reliable method of obtaining a biopsy of a tumor or lesion
located on an X-ray.
Accordingly, it is an object of the present invention to provide an
improved method and apparatus for locating an insertion point and guiding
a biopsy needle to engage a tumor or lesion, the location of which has
been established by an X-ray.
A further object of the present invention is to provide a laser beam
locating and guiding means for use in taking a biopsy of an X-rayed
specimen, the means being removably mounted on the X-ray machine between
the X-ray head and the specimen.
It is a further object of the present invention to provide an improved
laser beam locating and guiding means for directing the guiding and
locating beam at a predetermined angle to eliminate parallax.
These and other objects of the invention should be apparent from the
following detailed description for carrying out the invention when read in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an X-ray machine equipped with a laser beam
head embodying the present invention;
FIG. 2 is a plan view of a clamping plate of the type used in X-ray
examination of the female breast;
FIG. 3 is a front perspective view from below of the carriage which
supports the laser beam sources for the laser beam head;
FIG. 4 is an exploded perspective view of the laser diodes and their
supporting block;
FIG. 5 is a diagrammatic view of the laser beam source in various positions
illustrating the compensating mirror movement to maintain the image
position fixed;
FIG. 6 is a top plan view of the laser head with the top wall cut away for
illustrative purposes;
FIG. 7 is a sectional view of the laser head taken on line 7--7 of FIG. 6;
FIG. 8 is a sectional view of the laser head taken on line 8--8 of FIG. 6;
FIG. 9 is a diagrammatic view of an alternative embodiment of the
invention;
FIGS. 10a, 10b and 10c are schematic diagrams of the action of the laser
beam control by the alternative embodiment of FIG. 9;
FIGS. 11, 12 and 13 are schematic diagrams of the action of X-ray and light
beams and the problem of parallax;
FIG. 14 illustrates a still further embodiment of the invention to
eliminate parallax;
FIG. 15 illustrates a preferred embodiment of the invention;
FIG. 16 is an exploded view of the manner of calibration adjustment of the
laser head of FIG. 15 to the X-ray beam;
FIG. 17 is a diagrammatic view of a cam and cam follower for adjusting the
laser beam to be coincident with an X-ray beam through a lesion;
FIGS. 18 and 18a are views of a bottom diaphragm plate of an X-ray machine;
and
FIG. 19 is a view of a top plate for attachment to the bottom plate of the
X-ray machine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 of the drawings, there is shown an X-ray machine 10
which may take the form of any commercially available machine used for
diagnostic examinations of the female breast as in mammography. With the
recognition of the importance of early detection of cancer in improving
the chances of successful treatment, there is increasing use of such X-ray
machines in early detection of cancerous tumors or lesions. When such
tumors or lesions are noted on X-ray images, it is usually necessary to
take a biopsy of the tumor or lesion for further testing to determine the
nature of the treatment that should be given to minimize the risk to the
patient. Because of the small size of the tumors or lesions in this early
detection stage, it is often difficult, time consuming and painful to the
patient to obtain the desired biopsy of the tumor or lesion.
The X-ray machine 10 includes an X-ray head 12 from which the X-ray
radiation takes place. The radiation is directed toward a support platform
14 which is adjustable in height to support the specimen to be examined,
such as a female breast. The machine 10 is provided with a support column
16 and a body portion 18. The platform 14 includes means for disposing the
X-ray film beneath the specimen so that when exposed to X-ray radiation
from the head 12, an image of the specimen is produced on the film. The
illustrated machine 10 is commercially available from Instrumentarium
Imaging Corporation of Finland. Manifestly, X-ray machines of other
companies may be used with the present invention.
In order to immobilize and clamp the specimen during the X-ray examination,
it is common practice to use paddle or clamping means 20, as shown in FIG.
2. The clamping means 20 is mounted in parallel spaced relation to the
support platform 14 and is adapted to apply a pressure of on the order of
thirty pounds to the specimen during the initial X-ray examination. The
pressure is reduced substantially during the biopsy. In the examination of
a female breast, the clamping means 20 would be spaced 2 to 7 cm from the
upper surface of the platform 14. To expose a portion of the specimen so
that a biopsy may be taken by a biopsy needle 21, the clamping means 20,
often called a "paddle", is formed with a opening 22 which is usually in
the shape of a rectangle. At the edges of the opening 22 there are indicia
24 which permit the designation of locations with the opening 22 by
coordinates such as C-1.5, indicating a location aligned with the letter C
and the number 1.5. It is known to use such a clamping means provided with
this type of indicia to locate a tumor from which a sample is to be taken
by a biopsy needle. These clamping means are conventional in the art and
need not be described in detail herein. The method and apparatus of the
present invention provides a more accurate means of locating such a tumor
and performing a biopsy than is now possible with presently known methods
and apparatus.
The X-ray machine 10 is provided with means for detachably mounting a laser
head 24 immediately below the X-ray head 12 so that the laser beams are
radiated substantially along the same axis as the X-rays radiated toward
the platform 14. As will be described in connection with a second
embodiment in FIGS. 11-19, the X-ray emanates from what is considered a
point source at a location about 20 inches above the X-ray film which is
located beneath the paddle. The second embodiment is directed to
eliminating parallax so that the biopsy needle is directed along a
controlled angle from the X-ray point source to the lesion, as will be
explained in greater detail hereinafter.
As shown in FIGS. 6-8, the laser head 24 is enclosed in a housing 26 which
has closed an opening 26a in its bottom wall, as shown in FIG. 7. The
opening 26a is for the purpose of allowing laser beams to be directed from
within the housing 26 downwardly onto a specimen on the platform 14.
Within the housing 26 there is secured a frame 28 which supports a movable
carriage 30. The carriage 30 is supported and guided for horizontal
movement by a pair of spaced parallel rods 32 secured to opposed front and
back walls 34 and 36 respectively of the frame 28, as shown in FIG. 6.
The carriage 30 is of generally inverted U-shaped configuration having a
central portion 30a which extends across beneath the rods 32 and
terminates at depending sidewalls 30b. As shown in FIGS. 3 and 8, the
carriage 30 is formed with upwardly extending ears or tabs 30c which mount
bearings for supporting the carriage for sliding movement along the rods
32. In order to traverse the carriage forwardly and backwardly along the
rods 32, a threaded feed screw or shaft 38 is provided between the rods 32
and journaled for rotation in the walls 34 and 36, as shown in FIG. 6. The
feed screw 38 is rotated by a reversible motor 40 which drives the screw
38 through an idler gear 42 engaged by spur gears on the motor shaft and
the screw shaft 38. At the middle of the carriage 30, there is provided a
feed nut 44 which is secured to wall 30a of the carriage and which has a
threaded opening to receive the screw shaft 38. Thus, as the screw shaft
38 is rotated by the motor 40, the carriage is caused to traverse along
the screw 38 and the rods 32.
As is best shown in FIGS. 3 and 4, there is provided a laser support block
46 which is mounted for lateral movement with respect to the carriage 30.
The block 46 provides support for the means for generating the laser beams
which are used for locating and guiding a biopsy needle as will be
explained in detail below. The sidewall | | |
