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Description  |
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TECHNICAL FIELD
The present invention relates to a method, in conjunction with the X-ray
exposure of an object, of localising the three-dimensional position of a
spot in the object.
BACKGROUND ART
In many contexts, it is desirable to be able to localise a spot within an
object and, for example, to guide and insert an instrument to exact
position in the spot. This is of particular importance in breast cancer
diagnosis using int. al. fine-needle biopsy which may be considered as
included in the clinical and cytological components in triple diagnostics.
This triple diagnostics procedure generally includes mammography, clinical
examination and cytology. Fine-needle biopsy or fine needle puncture with
cytological examination of cell samples from a suspected region provide
very reliable positive responses. Furthermore, it is desirable, using
fine-needle biopsy, to be able to indicate a spot by means of a thin wire
marker for facilitating subsequent surgical excision biopsy.
OBJECT OF THE PRESENT INVENTION
The task forming the basis of the present invention is to realise a method
of localising, as simply, reliably and rapidly as possible, the
three-dimensional position of a spot in an object, for example a female
breast.
SOLUTION
This task is solved according to the present invention in that, after
fixation of the object in a pre-determined position, the object is exposed
by means of an exposure device in two directions, each on either side of a
centre line at right angles to the plane of the image for obtaining a
first image print and a second image print, the invention being
characterised in that the two-dimensional position of the target spot on
the two prints is established in relation to an index on the prints; and
that the coordinates of the spot in relation to the indices are processed
to obtain control signals for setting of a guidance instrument with means
for placing in the target spot in the object. The exposure device and the
guidance instrument are placed in the same centre reference from which the
right-angle centre line departs. The index is exposed on the print
preferably simultaneously with the object for obtaining an exact
measurement reference.
ADVANTAGES
The method according to the present invention makes possible the
localisation of an optional spot in an object, for example a female
breast, with a very high degree of precision in an extremely simple and
reliable manner. By applying the method according to the present invention
in conjunction with breast cancer diagnosis, it is possible to attain an
optimal spot in a female breast for fine-needle puncture, indication or
some form of directed therapy in a simple and rapid manner so that the
patient need not be subjected to undue stress or excessive discomfort.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The nature of the present invention and its aspects will be more readily
understood from the following brief description of the accompanying
Drawings, and discussion relating thereto.
In the accompanying Drawings:
FIG. 1 is a side elevation of a section of an apparatus for carrying out
the method according to the present invention;
FIG. 2 is a front elevation of the apparatus of FIG. 1;
FIG. 3 is a block diagram of parts included in an apparatus for carrying
out the method according to the present invention;
FIG. 4 is a top plan view of the parts illustrated in FIG. 3 but shown in
greater detail;
FIG. 5 illustrates the geometric conditions for the present invention;
FIG. 6 is a side elevation of parts of an apparatus for carrying out the
method according to the present invention;
FIG. 7 is a front elevation of the parts illustrated in FIG. 6;
FIG. 8 is a top plan view of the parts shown in FIGS. 6 and 7;
FIG. 9 is, on a larger scale, a side elevation of a number of the parts
illustrated in FIGS. 6-8; and
FIG. 10 shows, on a larger scale, a region from FIG. 9.
DESCRIPTION OF PREFERRED EMBODIMENT
The method according to the present invention will now be described in
greater detail in conjunction with the apparatus for its execution as
shown on the Drawings. The apparatus includes int. al. a per se known
mammograph 1 which may be of the type designated "Scenograph 500 T". The
mammograph 1 is pivotal about a shaft 2 which is provided with a scale for
the exact setting of the mammograph 1. A film cassette holder for a film
cassette 4 is mounted on an arm 3. A compression plate 5 is disposed above
the arm 3 with the film cassette 4. The compression plate 5 is, naturally,
vertically movable and has an orifice of, for example, 50.times.40 mm to
make possible the insertion of, for instance, a biopsy needle into a
breast which is held in a compressed state by means of the compression
plate 5 on the arm, and the film cassette holder 4. The path of radiation
from the tube in the mammograph 1 generating the X-rays is illustrated by
ghosted lines, the radiation path impinging upon a film in the film
cassette holder 4 for generating an exposed print which depicts the
exposed breast region. The apparatus illustrated in FIG. 1 further
includes a guidance instrument 6 which is shown in greater detail in FIGS.
6, 7 and 8 and parts thereof in FIG. 9. The above-mentioned parts 3, 4 and
5 may be considered as forming part of the guidance instrument 6, since
the parts 3, 4 and 5 are fixed in relation to the mammograph 1, pivotal
about the shaft 2. The compression plate 5 is transparent to X-rays so
that a greater portion of the object is exposed than the surface located
directly beneath the orifice in the compression plate 5.
FIG. 2 illustrates in greater detail the pivotal capacity of the mammograph
1 about the shaft 2. For executing the method according to the present
invention, a first exposure is taken with the mammograph 1 in the position
shown in FIG. 2 from the focal point FA with the film cassette in a first
position for generating a film print A, whereafter the mammograph is
pivoted and the film cassette is shifted for exposure in the focal point
FB and for generating a film print B.
Furthermore, for carrying out the method according to the present
invention, use is made of the parts illustrated in block form in FIGS. 3
and 4, while employing the graphic principle illustrated in FIG. 5. The
exposed prints A and B are placed on a measurement pad 7. The prints show,
apart from the spot 8 which it is desirable to localise and examine more
closely, also an index mark 9 on print A and an index mark 10 on print B.
The film cassette is arranged such that the index 9 and a letter A or
other marking are exposed simultanesouly with the object on the print A,
and the index 10 together with the letter B on print B, so as to avoid
confusion and to realise an exact reference on each print.
A monitoring unit 11 is included in the measurement pad 7 and is generally
entitled a cursor. For carrying out the measurement, the cursor is first
placed on the index of each respective print and thereafter, directly
above the spot which it is desired to localise, so as to obtain the polar
coordinates of the spot. The measurement pad 7 is coupled to a calculation
and guidance unit 12 in which the geometric calculations illustrated in
FIG. 5 are carried out and in which signals are generated for operating
servo-devices 14 in the guidance instrument 6 proper, by the intermediary
of a comparator circuit 13 with figure display in those cases when it is
desirable to carry out automatic setting of the guidance instrument 6 and;
in such an event, re-hook-up to the servo-devices is effected from the
guidance instrument 6.
The servo-devices 14 may be replaced by manual means and some form of
indicator for converting the signals from the calculation unit 12 to
setting values. This is carried out in the comparator circuit 13 which may
also be considered as a difference and trend indicator which includes a
figure display, by means of which the guidance instrument is set, and a
possible fine-needle can be placed in the target spot.
FIGS. 7, 8 and 9 show the guidance instrument 6 in greater detail and, as
will be apparent from these Figures, the arm 3, the film cassette holder 4
and the compression plate 5 are associated parts of the guidance
instrument. In the orifice in the compression plate 5, it is possible to
move an upper needle retainer 16 and a lower needle retainer 17 on the X,
Y, and Z axes. The lower needle retainer 17 is vertically movable
independently of the upper needle retainer 16. The needle retainers 16 and
17 are guided using servo motors 18, 19 and 20, and the desired position
of the needle tip can be read-off on displays for the exact localisation
of the needle tip in relation to the value calculated using the
calculation unit 12 in such a manner that the needle tip can be placed in
the spot or region 8 illustrated in FIG. 9.
Adjustment of the guidance instrument 6, and, thereby, the needle retainers
is suitably effected such that the position of the needle retainers 16, 17
on the X, Y and Z axes is first set, whereafter the fine-needle is placed
in the retainers 16 and 17, and, on abutment against the upper retainer
16, the needle tip is in the correct position. This adjustment may very
well be executed using the servo devices, while the vertical motion of the
lower needle retainer 17 or needle guider is effected manually. With the
needle retainers 16 and 17 in the correct position, an acoustic signal is
generated which may possibly also be combined with a light signal. This is
illustrated in greater detail in FIG. 9. In this case, it is desirable to
carry out closer examination of region 8 of the female breast 21, which is
compressed between the film cassette holder 4 and the compression plate 5
and has been in such state during exposure of the two prints A and B and a
subsequent input using the cursor on the measurement pad 7 and the
following calculations of adjustments values for the guidance instrument
6. It should, here, be observed that all parts included in the apparatus
are, as it were, "on-line", which ensures a very rapid execution of the
method.
According to FIG. 9, the needle 15 shall be moved from the position shown
by ghosted lines to the position shown by solid lines. After setting of
the X and Y axes of the needle retainers 16 and 17, the lower needle
retainer is employed for insertion of the biopsy needle to the region 8.
Different steps may be implemented, depending on the structure of the
biopsy needle.
FIG. 10 illustrates how a marker wire 22 is placed in the region 8 so as,
on later surgical excision, to guide the surgeon to the region 8. It is an
extremely delicate, if not entirely impossible operating to find region 8
without the help of the wire marker, since the region 8 may be as small as
one or two mm.
The method according to the present invention greatly facilitates breast
cancer diagnosis and, above all, makes for developments of the earlier
mammography in an extremely rational and reliable manner. The method
according to the present invention also makes for an extensive development
of the methodology of mammography examination without entailing greatly
increased burdening of therapeutic activities. The present invention also
provides the possibility of a considerable refinement of therapeutic
methods in an extremely gentle and careful manner and at low cost.
Employment of the method according to the present invention also makes for
considerably earlier identification of malignant areas during the most
occult stages, whereby treatment without surgery may be conceivable.
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