Note: Descriptions are shown in the official language in which they were submitted.
2~
Background of the Invention
_ . _
The present invention relates in general to
an apparatus and associated method for the detection
of cancerous tumors. More particularly, the inven-
tion relates to a system for the screening of cancer-
ous tumors particularly female breast tumors. Even
more particularly, the present invention relates to a
microwave system for breast screening for locating
tumors.
There is a continuing need for providing a
reliable, noninvasive and nonhazardous technique for
the detection o~ cancerous tumors especially breast
tumors. One such -technique ls an infrared thermo-
graphic technique for cancer tumor detection, based
on elevated temperatures often found in malignant
tumors. This technique is noninvasive and nonhazard-
ous but i~ of questionable accuracy. A more accurate
technique is mammography. One objection to the well
known
~29~L220
mammography technique is that it exposes the person to
hazardous x-rays. With regard to infrared thermography, one of
its drawbacks is its poor penetration through biological
tissues, resulting in the measurement of only surface
temperature.
Reference is also maae to my ~.S. patent 4,346,716 covering
a microwave detection system for detection of cancerous
tumors. This system employs a single detection antenna. If
this system i5 employed for breast screening the examination
time is far too long and is thus unacceptable. Furthermore,
even though microwave techniques provide subsurface sensing,
,
there is some limitation on the limit of depth detection.
In one prior system employing a single antenna this had to
be mechanically positioned requiring approximately 1.5 minutes
per site and a minimum of 9 positions per breast in order to
provide acceptable coverage. This resulted in a time of
e!xamination of 30-40 minutes. Again, this is too long a period
of time for practical purposes.
A further problem realized with the single antenna system
is associated with the depth of the tumor, particularly in
large breasts. It was found that there was a resultant high
number of particularly false negative readings.
Accordingly, it is an ob~ect of the present lnYention to
provide an improved method and apparatus for the detection of
~ ~ ~ \
g~2~
cancerous tumors, particularly breast tumors.
Another ob~ect of the present invention is to provide an
improved breast screening technique employing microwave
detection principles.
A further ob]ect of the present invention is to provide an
improved microwave breast screening system employing multiple
antennae which is instrumental in dramatically reducing the
examination time.
Still another object of the present invention is to provide
an improved microwave breast screening system in which all
antennae are stabilized at the same time eliminating thermal
drift due to both patient and environmental changes.
A further object of the present invention is to provide a
microwave breast screening sys~em used in combination with
breast compression so as to permit examination from opposite
surfaces of the compressed breast tissue.
StilI a further object of the present invention is to
provide a microwave breast screening system having multiple
antennae in which any given antenna thereof may be optimi2ed
for a given site. For example, the match of the nipple area of
the breast is different from the surrounding tissue and thus
the antenna element associated therewith can be optimized as to
impedance match for that particular site.
~312~0
Su~mary of the Invention
To accomplish the foregoing and other objects, features and
advantages of the invention, there is provided both an a means
for supporting these antennae in an array that conforms
substantially in size to the breast being screened. In
addition ~o the use of a plurality of antennae, there is also
provided in accordance with the invention means for compressing
the breast so as to reduce the tissue thickness being
examined. Means are provided coupled from trhe receiving
antenna array for detecting the temperature readings
corresponding, respectively, to the breast ~emperature at the
sites underlining the receiving antennae. In accordance with
one embodiment of the invention usable in particular for
screenlng small breasts, the antennae are supported in a
housing having a cupped surface at which the antennae are
supported. The antenna array is substantially symmetric so as
to provide multiple uniform breast coverage. In this
embodiment of the invention as well as in the second embodiment
to be described hereinafter each antenna has a domed end at the
housing cupped surface so as to prevent air pockets between the
housing and breasts. In the embodiment of the invention
employing a single set of antennae the compression i6 carried
out manually by the person being screened by virtue of
providing a gripping bar associated with the apparatus, which
: ,. ., , . -, ~ . - -
~Zgl~20
gripping bar enables the person to firmly hold the antenna
array against the breast. In this embodiment the cupped
surface is su~ported substantially vertically.
In accordance with the second embodiment of the present
invention, there are provided first and second sets of
receiving antennae. In the embodiment disclosed herein there
are six upper and six lower antennae. The means for supporting
these antennae includes first and second housing~ each having a
cupped surface at which the first and second sets of antennae
are respectiY~-ly supported. In this arrangement compression of
one brea~t is followed by compression of the other breast. In
this regard the first and second housings are commonly mounted
with the associated cupped surfaces disposed in facing relative
relationship ~ith the first housing disposed substantially
horizontal and ~n a fixed position and the second housing being
supported ~ver-the first housing. In this embodiment the means
for compressi~n includes carriage means on ~ support member and
means for operating the carriage means to bring the second
housing toward the first housing to compre-~s the breast between
the housings. There is pre~erably provided a pivotal
adiustment and a pivotal posittoning of the second houstng so
that the second housing is at an angular tilted position
relative to the f irst housing. This pivotal adjustment enables
the operator of the apparatus to provide the proper amount of
.. .
.,, ' . . .- ' .
~291~2~
compression so that the antenna array is firmly disposed
asainst the breast but at the same time does not make the
compression uncomfortable to the person.
The breast compression that is used in accordance with the
present invention has been found to provide many advantases.
The compression reduces the material thickness and thus makes
readings more accurate. With the dual housing arrangement
there may then be a determination of depth by Yirtue of this
compression because there will be examination from opposite
surfaces of the compressed tissue. Furthermore, compression
leads to tumor enhancement because of ~he reduced blood
circula~ion thus reducing the temperature of the tissue
surrounding the tumor with respect to the tumor tissue itself.
The cancerous tissue tends to be hotter and by restricting the
blood flow via compression this tends to enhance the
temperature differential between the tumor site and the
surrounding tissue.
In accordance with the associated method of the invention
there are provided either a single or two pluralities of
microwave receiving antennae. These are supported in either a
single or two arrays with each array conforming substantially
in size to the breast that is being screened. In either
embodiment described herein, the breast is compressed so as to
reduce tissue thickness that $s being examined. Using a single
,. .
ff,~
~ , .
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,. ., , , .; . ~
1'~91220
set of antennae the breast is compressed inwardly under
operation of the person being tested. In the second embodiment
of the invention in which there are two sets of antenna arrays
the breast is disposed between the array housings and the
housings are brought together to cause compression.
Compression of one breast is followed by compression of the
second breast with common points on each breast being
compared. In making these comparisons if there is a
temperature differential between like sites on either breast
then this may be an indication of a heated site area occasioned
by the subsurface presence of a tumor.
Brief Description of the Drawings
Numerous other objects, features and advantages of the
invention shoulo now become apparent upon a reading of the
following detaile~ description taken in conjunction with the
accompanying drawing, in which:
FIG. 1 is a perspectiVe View illustrating a first
embodiment o~ the present invention employing a double antenna
housing with the housings in vertical adjacent position;
FIG. 2 is a side elevation view partially in cross-sectlon
illustrating this first embodiment of the invention employing a
pair of antenna housings and furthermore illustrating the
compression of the breast between these housings in
substantially horizontal ad~acent positionS
--7--
9~ ~ O
FIG. 3 is a further side elevation view partially in
cross~section and illustrating ~urther details in connection
with the embodiment of FIG. 2;
FIG. 4 is a partial cross-sectional plan view taken along
line 4-4 of FIG. 3;
FIG. 5 is a partial cross-sectional plan view taken along
line 5-5 of FIG. 3;
FI~. 6 is a partial cross-sectional rear elevation view
: taken along line 6-6 of FIG. 5;
FIG. 7 is a partial cross sectional front elevation view
taken along line 7-7 of FIG. 4;
FIG. 8 is a cross-sectional view through one of the
antennae as taken along line 8-8 of FIG. 7;
FIG. 9 is a plan view of an alternate antenna construction
:In accordance with the invention for use with larger breasts;
F~G~ is a cross-sectional view taken along line 10-10 of
. .
FIG..9;
FIG. 11 is a further cross-sectional view showing further
details as taken along line 11-11 o~ FIG. 1~:
FIG. 12 is a plan view of the apparatus of the invention in
the second embodiment of the invention in which the housing is
substantially vertical and furthermore illustrating the
compression of one breast against the antenna arrays
--8--
9~ ~ZO
FIG. 13 is a plan view of the antenna array in the
embodiment of FIG. 1~;
FIG. 14 is a cross-sectional view of the antenna array of
~IG. 12 taken along line 14~14 of FIG. 13;
FI~. 15 is a schematic circuit diagram of a microwave
radiometer employed in the system of this invention;
FIG. 16 shows the single housing antenna pattern
FIGS. 17-19 show one version of the dual housing antenna
patterns for different antenna placement positions;
FI~S. 20-22 show another version of the dual housing
antenna patterns for different antenna placement po~sitions;
FIG. 23 illustrates a microwave thermogram and associated
temperature plot for the single housing antenna pattern; and
FIG. 24 is a circuit diagram associated with the control
electronics associated with temperature measurement.
,~ ,
Detailed Description
Referring now to the drawings, there are described herein
.
basically two different versions of detection apparatus ~or the
microwave detection of breast tumors. In one version as noted
in FIG. 12~ there is the use of a single antenna housing. This
is usable in particular with small breasts. For normal size to
large breasts the dual housing arrangement is employed such as
illustrated in FIGS. 1-3. In the dual housing arrangement the
_g_
` ~X91~20
breast is compressed between the two housings as noted in
dotted outline in FIG. 2. In either case in accordance with
the invention there is provided a plurality of microwave
receiving antennae. These` antennae are used, as previously
mentioned, in association with physical compression of the
breast. Tbe co~pression occurs in the second version as noted
in FIG. 2. In the first version of the invention the
compression occurs by virtue of the person being examined
compressing the antenna array inwardly toward the chest against
the breast.
The breast compression that is used in accordance with the
present invention has been found to provide many advantages.
The compression reduces the material thickness and thus makes
readings mor~ accurate. ~ith the dual housing arrangement
there may then -be a determination of depth by ~irtue of this
compression ~-écause there will be examination from opposite
surfaces oî the compressed tissue. Furthermore, compression
:leads to tumor enhancement because of the reduced blood
circulation thus reducing the temperature of the tissue
surrounding the tumor with respect to the tumor tissue itself.
The cancerous tissue tends to be hotter and by restricting the
blood flow via compression this tends to enhance the
temperature differential between the tumor site and the
surrounding tissue.
--10--
., " ' ~ , '
~91~0
The use of multiple antennae provides improved
performance. The individual antennae can be site-optimized.
Also, data acquisition is possible thus dramatically reducing
drift in both equipment and the patient. As indicated
compression reduces tissue thickness and allows measurement
from opposite surfaces of the breast. This enhances the
ability to locate deep lesions. The results that are obtained
can be carried out so that they can be readily compared to
measurements takèn by way of mammography techniques.
As indicated before, the multiple antenna approach results
in improved performance due to site-optimized antennae. The
multiple antennae reduce the examination time because all
antennae are thermally matched simultaneously, allowing rapid
data acquisition. Rapid data acquisition in turn eliminates or
dramatically reduces dri~t due-to environmental, eguipment or
patient conditions.
As mentioned previously, one of the advanta~es of the
present invention is the reduction in examination time.
However, it is further noted that with the use of both
compression to reduce the tissue thickness and the ability to
look from two opposing surfaces, this enables one to look deep
into particularly large breasts. In addition, the use of
multiple antennae allow site optimization of the antenna
element~, such as might be necessary in the area of the nipple.
, . ,. . - ~
~l29 1 220
Now~ with regard to the drawings and in particular to FIG.
1, there is ill~strated the apparatus of the present invention
which comprises a slide assembly 10 that may be secured to a
wall in a room. This slide assembly 10 supports a beam 12
which is adapted to be maintained in a horizontal position as
illustrated in FIG. 1. However, the beam 12 is pivotal about
the axis 14. The beam 12 is carried in a vertically movable
carriage 16 supported from cables 18 that extend from the
counter balance assembly 20. The assembly 20 is at the top of
the slide assembly 10. There is also provided a lock 22 that
locks the carriaye 16 in a desired vertical position. There is
also provided a rotational lock 24 that locks the beam 12 in a
certain horizontal rotational position. The operator of the
apparatus can easily release the locks 22 and 24 to move the
c~rriage 16 up and down and also to move the beam 12 in a
horizontal plane. The beam 12 at its outer end supports the
ver~ical post 26. The post 26 may be firmly secured a~ the end
o~ the beam 12 and supports at its lower end bracket 28.
Bracket 28 is an L-shaped bracket that is clearly illustrated
in FIGS. 2 and 3. The interconnection between the bracket 28
and the post 26 permits pivotal ~rictional rotation between the
bracket 28 and the post 26. This likewise permits rotational
movement in a horizontal plane of the antenna housing 30.
The bracket 28 includes a leg 29 that is secured to the
-12-
~ . .. .
9 ~2 Z 0
rotational pivot 320 The rotational pivot ~2 is also secured
to the main support member 34 of the apparatus. The rotational
pivot 32 permits the sup~ort member 34 to rotate essentially in
a vertical plane. In this regard, FIG. 1 shows the support
member 34 in a horizontal position while FIG. 2 shows the
support member 34 in a vertical position.
In FIGS~ 1 and 2, double antenna housings are employed, but
illustrated in different respective positions. In the instance
illustrated in FIG. 1 the antenna housings 38, 48, (housinq 48
being disposed behind housing 38) are both disposed in a
vertical position corresponding to the le~t side lateral
position illustrated in FIG. 19.
Hereinafter, in connection with FIGS. 12-14, there is an
illustration of a si~gle housing that is used. A single
housing version of ~he invention is usable in particular with
breasts of a size on ~he order of 4" or less.
For larger brea~s that are defined herein as being in
sizes of 5 1~2n, 7" or 9" the apparatus such as illustrated in
FIGS. 1-3 are employed in which there are a pair of antenna
housings. As far as the portion of the apparatus that supports
the housings is concerned, the same basic construction is used
in connection with the description of FIGS. 1-3. Accordingly,
like reference ~haracters are of course used to identify like
parts including the support member 34 illustrated herein~ The
-13-
; i, . ,, , ,~ , ,, ,, ~
9~.~Z~
antenna housing 38 is the lower most housing and includes a
cupped surface 39 at which the antennae 40 are supported in an
array 41. The housing 38 is supported at the very bottom end
of the support member 34. There is provided a lower housing
clamp 42 that locks the housing 38 in position. Above the
clamp 42 is a further lock 44 that is used to lock the position
of the rotational pivot 32.
~ ith resàrd to the rotational pivot 32 it is noted that it
is basically maintained in one of two different positions which
are displaced 90 to each other. Again, in FIG. 1 it is shown
in one position and in FIG. 2 it has been rotated 90 50 that
the support me~ber 34 is in an upright position thus enabling
the housings to be disposed on the support member in overlying
relationship as illustrated in FIGS. 2 and 3~
The second antenna housing 48 is disposed in overlying
relationship to the ~lousing 36 -and-also has a cupped surface 49
at which the ante~n~ 50 are ~upported. The antennae 50 are
supported in an array 51.
The antenna housing 48 is also ,supported from the support
member 34 but rather than being supported in a fixed position
as is the housing 38, the housins 48 is supported both in the
manner to Fivot and also in a manner to move vertically
relative to the housing 38. The housing 48 is supported from a
U-shaped bracket S2 illustrated in a plan view in FIG. 5. The
-14
` ` 1291~20
housing 48 is locked to the bracket 52 by means of the clamp
54. The housing 48 enyages with the U-shaped bracket 52 and
the sliding relationship therewith such as illustrated in FIG.
5.
As illustrated in FIG. 2, the support member 34 has side
pieces 56 and 57. The side piece 57 carries the scale 58. The
scale 58 as illustrated in FIGS. ~, 3 and 5. The side piece 56
supports the rack 60.
In FIGS. 2, 3 and 5 there are shown two control knobs
as~ociated with operation of the housing 48. One is the knob
62 and the other is the knob 64. The knob 62 is used to
control the distance between the housings. This knob is
attached to a shaft 63 that carries the pinion gear 65 that is
adapted to enga~e with the rack 60. In this regard also note
the cro~s-sectional view of FIG. 6 which shows the knob 62
connected to the pinion gear 65 which in turn is engaged with
the rack 60.
The knob 64 clamps the rotational position of the antenna
housing 48. This pivoting of the housing 48 is at the pivot
70. gnob 64 clamps the lock bars 68 against the frame to hold
the antenna arrays in the proper angular position. As
illustrated in PIGS. 3 and 5 there are also a pair of lock bar
6a associated with the pivot 66. In FIG. 5 the pivot for the
housing 48 rotation is at 70.
-15-
~L29~220
Thus, the rack and pinion are engaged in order to move the
housing 48 up and down and the knob 64 is used to clamp the
housing 48 in a predetermined rotational position with the
housing 48 rotating about a pivot axis as indicated,at 70 in
FIG. 5. FIG. 5 also shows the Teflon slides 71 disposed on
either side of the rack 60 and also on the other side of the
side piece 56. FIG. 5 furthermore illustrates the dial 73
which indicates rotation of the housing 48. In this regard
also note the dial 73 in FIG. 3 indicating a degree of rotation
of approxi,mately 15. The scale 58 is also illustrated in ~IG.
3 and gives an indication of,the displacement between the two
hou'sings. With regard to the dial 73 this is fixed to the
U-shaped bracket 52 and thus rotates with the housing so as to
indicate angular displacement of the housing 48.
FIG. 3 illustrates in dotted outline the antenna array 41
associate~ith housing 38 and also shows in cross-section the
antenna array 51 associated with the housing 48. There are
leads 76 c~pling from each of the antennae 40 of array 41.
These leads couple to a connector 77 and then there are output
leads that couple from the housing 38. Similarly, there are
leads 78 coupling from the antenna array 51 to a connector 79.
From the connector there are leads that couple out of the
movable antenna housing 48.
FIG. 4 is a plan view taken along line 4-4 of FIG. 3. Thi~
-16-
.; . ~ .,
~ .
:
. ~29~20
illustrates the particular placement of the antennae 40 in a
triangular shaped array all disposed within the cupped surface
39. FIG~ 4 also illustrates the coupling 77 and ehe coupling
of leads out of the housing 38. FIG. 4 also illustrates the
clamp 42 for clamping the housing 38 in position. In the
particular embodiment illustrated as FIG. 4 the antenna array
is for use with an intermediate size breast such as the
aforementioned 5 1/2" breast. The particular array has a lower
most row of three antennae spaced apart, a second row of two
antennae staggered in relationship to the first row and a third
single antenna altogether making the triangular shape as
aforementioned.
Reference is now made to ~IG. 6 which is a rear elevation
vi~.w partially in cross-section showing further details of the
appa~atus illustrating the movable and rotational upper housing
~le.~nd the fixed lower housing 38. There is illustrated the
r~at-ional clamp knob 64 and the knob 62 for setting the
dijtance apart ~etween the housingsO FIG. 6 also illustrates
the ~lamping or loc~ bars 68, spacers 80t and fiber washers
81. Pins 82 are disposed in association with the non-rotating
washer 83.
.Reference is now made to F~G. 7 that illustrates a
cross-sectional view with the two housings in confronting
relationship and which the cupped surfaces 39 and 49 are in
-17-
.,
.
; , ; . ~,~ ;
~9~o
facing relative relationship to each other. Therebetween there
i~ shown a dotted outline a warming blanket 84 which is
preferably used to warm the cupped surfaces prior to usage as
will be described hereinafter. It is furthermore noted that
each of the antennae 40 and each of the antennae 50 has a domed
end 40A, 50A.
Reference is now made to FIG. 8 which is a cross-sectional
view taken along line 8-8 of FIG. 7 showing further details of
the afi~enna 40. This antenna is comprised of a section of
waveguide 85 and a probe 86 coupling to the coaxial line 87.
The waveguide ~5 is preferably dielectrically filled as shown
at 88 in FIG. ~. Also in FIG. 8 it is noted that there is
clearly described the domed end 40A of the antenna.
The embodi~ent of the invention illustrated in FIGS. 7 and
8 is used in connection with breast sizes of 5 1/2" and 7n~
~or ~-larger breast of 9" size then it is preferred to use the
a~tenna form illustrated in FIGS. 9~11. It is noted that the
breast diameter may be determined from previously available
mammo~graphy data. FIG. 9 shows the series of antennae 90
disposed in an array 91 covering an area that matches the size
of a relatively larse breast identified as a 9" breast herein.
As noted in FIG. 99 these antennae are disposed in the same
general pattern as previously illustrated in FIG. 4 in a first
row of three antennae, a second row of two antennae and then
-lB-
.
.
~.~9~
followed by a single antenna disposed in a staqgered
arrangement in a generally triangular array.
FIG. 10 is a cross-sectional view similar to that
illustrated in FIG. 7 but for the large breast embodiment of
the housing. Again, there is described in FI~. 10 the warming
blanket 84 and dotted outline used to warm the ends of the
antennae. The antennae 90 have domed ends 90A and the
overlying antennae 92 have domed ends 92A. Again, these domed
ends are for the purpose of preventing air pockets between the
breast and the antennae. FIG. 10 also illustrates the cup
surface 39 associated with housing 38 and the similar cup
surface 49 associated with housing 48.
FIG. 11 is a cross-sectional view taken along line 11-11 of
FIG. 10 showing some further detail of the microwave antenna
illustrating in particular the cupped surface 39, domed end 90A
and dielectric filling 94.
Thus, in this embodiment of the invention just described,
there are two housings as in the em~odiment illustrated in FIG.
8 each i~cluding 6 antennae of generally rectangu1ar
construction each comprising a section of waveguide and a probe
for detecting signals from the waveguide. There i~ an array of
antennae 91 associated with housing 38 and also an array 93 of
antennae associated with the housing 4B. Each of these arrays
as noted comprises six antennae each with domed surfaces.
-19-
'' . '
1.29~L~20
~ eference has been made hereinbefore to the embodiment of
the invention in which two housings are used such as in the
different positions of FIG. 1 and 2. Mention has also been
made of a single antenna housing 30 having associated
therewith, handle 35 as referred to in FIG. 12. PIG. 12 also
shows the outline of a breast 96. FIG. 12 also shows portions
of the apparatus described in FIG. 1 including the vertical
post 26, support member 34, and knobs 62 and 64. FIG. 12 also
shows in dotted outline an array 100 of antennae 98.
~ eerence is also made to ~IGS. 13 and 14. FIG. 13 shows
the housing 30 with the antenna array 100 comprised of six
antennae 98. Each of the antennae 98 may be of the
construction previously described such as shown in the detail
of.F~..B. The waveguide section thereof is preferably
dielectrlcally filled and the waveguide sec~ion has a domed end
102. ~ array of six antennae are disposed in the circularly
cuppea-s-~rface 104.
FIG..12 shows the placement of the breast compressed
against the antenna array 100 this compression is brought ab~ut
in this embodiment by virtue of the person being tested
grasping the handle 35 and drawing the housing 30 against the
breast to flatten the,breast and compress it so as to cover the
entire antenna array. As indicated previously this form of the
invention is employed in particular with small breasts tha~ may
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, :
~.291~20
be too small to effectively compress between a pair of
housings. Thus, instead a single housing is used with the
associated handle 35 for providing compression directly against
the breast.
Now, reference ~s made to FI~. 15 which shows a schematic
circuit diagram of a microwave radiometer that may be employed
in the system of this invention for taking temperature
mea~urements. Preferably, a single radiometer is employed and
readings are taken in succession from each of the antennae as
will be described hereinafter.
With regard to FIG. 15, there is illustrated an input to
the switch SWl from the receiver antenna such as from the
antennae 40 or 50 as illustrated in FIGS. 2 and 3. The
, . . .
microwave radiometer that is depicted may be of the DICKE
switch type. The radiometer desiqn substantially reduces the
. . _
effects of short term gain fluctuations in the radiometer. The
.
receiver input is switched by means of a switch SWl at a
constant rate between the antenna and a constant temperature
reference load. The switched, or modulated RF signal is
therefore inserted at a point prior to RF amplification and as
close to the antenna as possible; in turn, it is then amplified
and coherently detected. The final output is proportional to
the temperature difference between the antenna and the
reference load.
-21-
... " , , - . . ..
', . " ,., '., ~, ' ' ` `, - - . ' ~ .. , . . _.
~;~9~ O
In FIG. 15 a second switch SW2~ referred to as a
calibration switch, may also be employed. With this switch,
the reference load as defined by the noise diode 36A and fixed
attenuator 38Ao is compared with a base load 4QA rather than
with the signal from the an~enna. If the base load is equal in
temperature with the reference load, the DC output of the
ra2iometer is thus nulled to zero~
The radiometer described herein employs at least one low
noise RF amplifier in conjunction with a simple single ended
square law detector rather than the more complex
superheterodyne which employs a local oscillator and IF
amplifier. The square law detector of this arrangement
minimizes the potential drift and noise associated with the
superheterodyne approach. The conformance that comprises the
radiometer are di~cussed in detail hereinafter.
With r2s~rd t~^the microwave radiometer schematic of FIG.
15, at its i~ t the-e ~s shown the connection which is
pre~erably by way of a coax cable from the receiver antenna
lapplicator aperture) to one input of switch S~ hls may be
termed a calibration switch which is a solenoid-operated ,
mechan~cal single pole/-double-throw switch used to disconnect
the antenna and in its place connect the base load 4QA by way
of a second switch S~2. The switch SWl has an isolat~on or
switching radio, of greater than 60 dB with a corresponding
-22-
'
- . ~
1~9~2~)
insertion loss of less than 0.1 dB. The switch SW2 is used in
the calibration circuit to disconnect the base load and to
insert in its place the calibrated noise source as represented
by the ~ixed attenuator 38A and the noise diode 36A referred to
hereinafter.
As indicated in FIG. 15, there are three ferrite isolators
used in the receiver path. These are identified as isolators
ISOL-l, ISOL-2 and ISOL-3. The first isolator, is located
between the calibration switch S~l an~ the DICXE switch Sh'3.
Thi~ isolator is used to terminate the output of the reference
load when the DICKE switch is in the low loss state. In this
state, the reference or base load is circulated in the
direction of the antenna which, in this case, functions as a
ferriie isolator. ~he isolator ISOL-l employs a
c:oaxial~to-waveguide transition. The insertion loss of this
isol3~0r and the transition is less than 0.~ dB, with a
corr~ nding isolation of greater than 2.3 dB.
The second isolator ISOL-2 in FIG. 15, is disposed between
the switch SW3 and the first stage RF amplifier to maintain a
constant load match to this amplifier. Any reflections from
the RF amplifier would therefore be terminated in the
isolator. Again, this isolator, which is a waveguide isolator
with a coax-to-waveguide transition, has an insertion loss o~
less than 0.2 dB with an isolation o~ greater than 23 dB.
-~3
. . ., . ~. , , ~
.: ' "
1~9~L220
There is also provided in FIG. 15 a third isolator ISOL-3
which is located between the output of the first RP amplifier
and the bandpass filter 44A. ~he purpose of this particular
isolator is to present a constant load match to the output
stage of the first RF amplifier, and also to present a matched
input to the bandpass filter 44A.
A switchable ferrite circulator, designated switch SW3 in
FI~. 15, forms the load comparison, or DICKE switch, function.
A ferrite device is preferred over a semiconductor approach
primarily in view of the lower insertion loss, ~ypically les~
than 003 dB, and elimination of noise generated by the
semiconductor junction over and above the measured insertion
loss.
Br~efly, the device S~3 is a switchable ferrite junction
circulator utilizing the remnant, or latching, characteristics
of ~h-e Eerrite material. The principle of latchinq action îs
2~--fo-llows: Using the intrinsic properties of a hysteresis
loop of a ferrite toroid, a transverse magnetic field is used
across a portion of the ferrite exposed to an RF signal. The
biasing field is actually the residual inductance of the
ferrite toroid; therefore, the device needs no holding power
and can be reversed tn polarity using merely enough energy to
overcome the natural coercive force of the toroid.
For the system of this invention, the latching circulator
~24-
has been constructed in wave~uide having a single ferrite
element contained within the microwave circuit. The insertiOn
loss is less than 0.3 dB, having isolation in excess of 20 dB.
The first-stage RF amplifier may be a four stage FET device
constructed in microstrip with integrated biasing circuitry.
The noise figure of the first amplifier (M/A Canada amplifier
Model No. ~C-2019) is 2.0 dB with a gain of 35 dB. The secon~
RF amplifier Amplica Model No. 3441CS~ has a noise figure of
2.6 dB, with an associated gain of 33 dB. In both instancest
the noise figure includes the input ferrite isolator as
depicted in FIG. 15. With the input and output VSWR at less
than 1.5:1, the gain compression at signal levels of between
-5~ dbm to -10 dbm is less than 0.1 dB.
~ n ~IG. 15 the filter 44A is a bandpass filter and the
bandwtdth of the microwave radiometer is basically determined
by tne`~andpass characteristics of this filter. The filter is
dispos~d-dfter the first stage of RF ampli~ication to minimize
. .
the imp~ct of the insertion loss of the filter on the overall
system per-formance. The filter characteristics are chosen to
minimize possible interference due to nearby microwave
communications or radar band~. The ilter is preerably an
8-section bandpass ~ilter constructed in stripline. The pass
band loss is less than 3 dB and the bandwidth is approximately
500 MHz.
-25-
,~ 1,- ,
~29~2~0
As indicated in FIG. 15, there are basically two loads
provided, a base load 40 and a reference load 42A. The load
design is coaxial, employing a stainless steel R~ connector to
provide thermal isolation between the load and the remainder of
the system. The coaxial termination is containe~ within an
insulated housing and utilizes an integrated heater and
proportional control to maintain constant temperature. The
absolute temperature of both the base and the reference loads
is monitored and displayed on a digital temperature indicator
(not shown).
The calibration circuit comprises a precision, solid state,
noise source having an excess noise ratio, ENR of 33 dB. This
allows noise to be injected into the receiver front end via the
high isolation mechanical calibration switch. The output level
of the noise source is reduced through the use of a precision
calibrated pad (43.3 dB~. This calibration circuit is shown in
FI~. 15 as including a fixed attenuator 38A and the noise diode
36A.
The lock-in amplifier 50A shown in FIG. 15 enables the
accurate measurement of signals contaminated by broad band
noise, power line pickup, frequency drift or other sources of
interference. It accomplishes this by means of an extremely
narrow band detector which has the center of its pass band
locked to the frequency of the signal to be measured. Because
-2fi-
: , ~ ,' ' - . . . , `
. ' ' ' . . .'.
, .,
~ ~ 9 ~Z2~
of the frequency lock and narrow bandwid~h, large improvements
in ~ignal-to-noise ratio are achieved. This allows the 6ignal
of interest to be accurately measured, even in situations where
it is completely masked by noise. In addition, the lock-in
amplifier 50A provides the synchronous function associated with
the DICKE switch i.e., the unit supplies the 100 Hz reference
clock frequency to drive the ferrite switch driver.
The system is provided, of course, with a power ~upply
comprising two 12-volt 50 amp maintenance freet lead-acid
batteries in series, fused at 10 amps per battery. The outputs
from the battery assembly include 12 and 24 volts~ These
voltages are appropriately applied to the receiver and lock-in
amplifier. There may also be provided a voltage converter and
regulator;'' Status indicators may be employed for indicating
operating voltages. The main operating switch may have three
positions i'ncluding an on position, an off position and a
"charged" po~ition. In the charged mode, a meter is used to
monitor the charge current to the batteries which is limited to
approximately 6 amps. With a 3-6 amp-hour discharge rate (a
normal 12 hour operating mode), the recharge cycle is
approximately 10-12 hours (overnight).
With the' system o~ the present invention thermal drift i~
essentially eliminated. This is the case because all antennae
are positioned concurrently and all readings taken
-27-
... ~ .. .. . ...
- ' .
. . .
~ ~ 9 ~2 ~
substantially concurrently. Moreover, the antenna surface that
the breast contacts is warmed so that the readings can be taken
in ~ay 1 minute to say 1.5 minutes rather than waiting a
substantially longer time for proper temperature
stabilization. It is preferred to warm the cupped surfaces 39
and 49 and of course the associated antenna domed ends to a
t~mperature on the order of body temperature. This may be
carried out by means o~ a warming pad as has been illustrated
in the drawings. The preferred temperature ~hat the cupped
surfaces are raised to is in the range of 30C-34C. This gets
the surfaces that the breasts are going to come into contact
with close to human skin temperature.
As indicated previously, in the embodiment employing a
single antenna housing once the antennae are warmed the person
being examined can themselves press the antenna array against
the breast and readings can be taken in approximately 1 to 1.5
minutes. In the other embodiment of the invention that is more
universally used, the lower antenna housing is ~ixed in
position and the upper antenna housing moves downwardly and is
capa~le of pivoting as clearly indicated in FIGS. 2 and 3 of
thls application to cause compression of the breast such as
illustrated in dotted outline in ~IG. 2. It has been ~ound
that the upper housing generally does not become horizontal but
is instead moved to a position approximately as illustrated in
-~8~
'~, ' , ' ' ,
~1 ~9~20
FIG. 2 tilted at a slight anglè usually in the range of 10 -
35. It has been found that it is preferred not to have the
housings horizontal as this provides too much compression and
discomfort regarding these breasts being examined. It is only
necessary that the antenna array make good contact with the
tissue and that there be no air gaps between the antenna and
the tissue. It is also important that the antenna array be
somewhat matched in size to the breast being examined so that
all antennae are properly covered. Any air gaps will create a
mismatch. Also, in accordance with the invention the domed
antenna structure is important in assuring that air gaps or air
pockets do not form.
Reference is now made to FIGS. 16-22 in connection with a
. .
group of- schematic diagrams that illustrate each of the
different types of antenna arrays and the associated patterns
for each breast. In this regard, FIG. 16 relates t~ the single
antenna--housing version illustrated in FIGS. 1 and 12-14 o~ the
inVeD~iOn, FIGS. 17-19 show patterns associated with the dual
antenna~housings for 5 1/2" and 7" breasts. Finally, FIGS.
20-22 illustrate patterns in association with a 9" breast. In
FIGS. 17-22 the patterns are illustrated cranio-caudad oblique
and lateral, respectively.
FIG. 16 illustrates the antenna array 100 at the top for
the left side and at the bottom for the right side. This is in
-29-
! ' '
.
;'
~ 2 0
connection with a relatively small size breast considered to ~e
a 4" breast. Also note in FIG. 1~ the medial markers M. Each
of these arrays comprise six antennae identified as ~ 6.
It is noted in the array illustrated in FIG. 16 that four of
the antennae, ~l, #2, ~3 and ~6 are grouped more closely
together at the outside of the breast while ~4 and ~5 are
grouped closer to the medial marker M.
Now, it is noted that in FIG. 16 the outermost antenna is
~1 both with respect to the left breast and the right breast.
This i~ so that the ~1 readings are compared with comparisons
being made at common points on each breast. ~or example, the
right upper outer antenna ~6 is compared with the left upper
outer antenna ~6. Because when the breast is compressed
against the antenna array the antennae are actually in
different positions depending ~pon whether it is the left
breast or the right breast, information is fed into the system
so that the proper comparisons are made of a common point on
each breast. ~t may be, two separate housings 30 may even be
employed one f~r the left breast and one ~or the r~ght breast.
FIGS. 1~-19 illustrate schematically the antenna array
placements for the dual arrays, these are the arrays previously
referred to as arrays 41 and 51 in FIG. 7. Again, in, for
example, FIG. 17 the location ~1 on the left side i8 compared
with the location ~1 on the right side. The position of FIG.
-30-
7 . . , , . ', . ...
," ;' , .,
~ ~ 9 ~X ~ O
17 relates to the position of housings of FIG. 2~ Again, in
connection with FIGS. 17-lg it must be remembered ~hat when one
is observing both sides of the breast using six upper antennae
and six lower antennae. Thus, the right outer upper antenna is
compared with the same position on the left breast or in other
words the left outer upper antenna. Because the breasts are
inserted in the same direction between the antenna housings
this means that the equipment must int~rpret whether a left
breast or a right breast is being examined. It then senses the
signals from the antennae in the proper manner so that the
proper points are compared. For example, in FIG. 17 it is
noted that antenna ~6 on the left side appears to be in line
with antenna ~1 on the right side. However, the electronics in
t:he system interp~ets the readings differently so that the both
~1 sites are compared between left and right sides.
FIG. 17 illustrates the detection and compression as being
in the cranio-caudad diEection. FIG. 18 indicates the
compression ano sensing being at the oblique direction. In
F~G. 19 the sensin~ is done in the lateral position such as
illustrated previously in FIG. 1.
FIGS. 20-22 describes similar arrangements in connection
with the embodiment of the invention illustrated in FIG. 10.
This is for the larger breast employing arrays 91 and 93. Once
again, comparisons are made between the same common points on
-31-
: . ,
: , :
2 0
each breast. For example~ in FIG~ 20 the left upper outer
antenna ~1 is compared with the right outer upper antenna tl.
When the breast is inserted into the position between the
housings there may be in fact two different antennae that will
be used for detecting these common points but the electronics
interprets whether the left or right ~reast is being examined
and then takes the appropriate reading from the appropriate
antenna so that the common comparisons can take place.
In FIG. 20 the position is cranio-caudad. In FIG. 21 the
patt~rn is illustrated as oblique. In FIG. 22 the pattern is
lateral.
It,is further to be noted~that the compression that has
been referred to previously is also believed to lead to ~umor
enhancement. An elevated temperature is generally associated
with the tumor due to the metabolic activity of the tumor. The
cell~ are consuming energy and thus ge~erate heat. In a
cancerous tumor the cells double faster and thus are more
active ~nd generate more heat. Also, the tumor has generally
poor vascularity and thus cannot dump the heat that good.
Thus, when the blood circulating about the tumor is also
compressed this reduces the temperature of the surrounding
t~ssue with respect to the tumor tissue. This thus tends to
enhance the temperature differential between the tumor itself
and the surrounding temperature.
~ ' ~ . . , - r
( ~z ~ 2 0
As indicated previously, it is des~red to compare the like
or common locations between each breast to determine a
temperature differential therebetween. It is also desired to
have the capability of making a comparison ~etween a particular
temperature at an antenna loca~ion for comparison with the
average breast temperature. There is a possibility of cold
spots in the breast and thus it is preferred to average the
temperature throughout the breast and then make the comparison
of the average with each individual reading.
Reference is now made to FIG. 23 which shows a microwave
thermogram. Thls is in association with the embodiment of the
invention employing five antennae illustrated at the left
breast as antennae ~2t t4, ~6, ~8, ~10 and ~12. Associated
with t~e right breast are antennae ~1, t3, #5, ~7, ~9 and ~11.
Also s~own this plot indicating temperature associated with
r~ ~
each of the four numbered antennae. Also illustrated in FIG.
i .
23 is ~;,site 110 where a tumor exists. ~ith reference to the
drawing it- it noted that, for example, a comparison of common
points ~1 and ~2 indicates little or no temperature
differential~ The same also applies to a comparison between
common points ~3 and ~4. Now, a comparison between common
points ~5 and t6 indicates a temperature dif~erential. A
temperature differential is also indicated between common
points ~9 and ~10. However, note that the maximum temperature
-33-
. , ~ '' ~.. ~ ,'
,, - ' J `, , . , , ' ' . . :
~912ZO
differential is detected at the antenna ~12 where the
temperature differential between ~11 and ~lZ is on the order of
2 o5C~
Again, in FIG~ 23 direct comparisons of common point for
common point are made. HoweYer, in an alternate embodiment o~
the invention each of the antenna sites may be compared with a
common average. This is desired because a temperature
differential does not necessarily indicate a tumor if there is
a cold spot. It may simply indicate that there is an elevated
temperature of good tissue in comparison with the cold spot.
Therefore, by a~eraging all of the breast temperatures this
should eliminate all of the problems associated with detection
of cold spots.
As indicated previously, by compressing the breast, one
reduces the tissue thickness. This is particularly helpful in
connection with the measurement of large breasts in which there
may be difficulty obtaining proper measurements by surface
contact without compression. It is also noted that with the
double antenna arrangement, one is measuring ~rom opposing
surfaces. This allows determination of depth, which again is
particularly helpful in larger breasts, although it also
applies to all breasts. For example, if a tumor is located
midway between the two opposing antennae of a particulas
brea~t, thè signal strength is approximately equal at both
~34
'',' . ', .' "'., '''
~ ~9~220
antennae. However, if the tumor is offset, the degree of
offset can be ~etermined by the signal strength at the two
opposed antennae. By way of example, refer to PIG. 17 and the
arrays 41 and 51. At the same breast, like opposed antennae
positions may be sensed to determine the position of tumor
therebetween. ~urthermore, by using opposed antenna arrays,
this means that either side of a particular breast can be
examined with a reduced path length by a factor of 2, because
one is looking fro~ two opposing surfaces.
FIG. 24 is a schematic diagram illustrating some of the
electronics that may be employed in providing some of the
comparisons previously referred to. In FIG. 24 there are shown
the arrays Al and A2 each of which have multiple antennae
coupling to the processor 120. It is noted that the arrays ~1
and A? couple to a multiplexing switch 119 of conventional
clesign. The output of the switch 113 couples to the radiometer
R and the output of the radiometer couples to the stores 121
and 122. ~he radiometer R detects the respective temperature
signals from the antennae and the processor 120 records these
signals for subsequent processing.
The processor 120 may be a computer that has certain inputs
coupled thereto by a keyboard for indicating whether one or the
other breast is being examined. Thus, ~or example~ i~ it is
assumed that the left breast is being examined then a
.
-35-
.. j,., ., " " . " ~ .. ~, i ~ i . .
.j", .~ , .. . . . ..
s, -;
,~ j " - . , -:
9 ~2z o
particular pattern of storage occurs in devices 121 and 122 so
as to provide points on the left breast that can be compared.
When the right breast is then compared like signals will be
coupled to store 121 and 122 for the sake of discussion herein
store ~1 in EI~. 24 may be considered as being associated with
the left breast while store ~2 is associated with the right
breast.
In FIG. 24 there is shown one comparator 124. It simply
receives signals from each of the stores 121 and 122 for making
a dir æt comparison which is the comparison i~lustrated in FIG.
23 between common points on each breast. Also illustrated in
FIG. 24 is an averaging circuit 125 and a second averaging
circuit 126. The averaging circuits take all of the locations
associated with the left breast and average them and the
averaging circuit 126 takes all locations associated witb the
rignt breast and averages them. Also illustrated in FIG. 24
are two other comparators 128 and 129. The comparator 128
compares---the average with readings from the left breast and the
comparator 129 compares the average with readings from the
right breast. A further comparator may be used to compare the
outputs from the comparators 128 and 129~
Aga-in, in summary it is desired to make comparisons between
common points on each breast. This may be made on a direct
comparison basis but preferably i8 made by comparing the
-36-
, , . : .
.
;
~9~LX20
reading from an antenna with average breast temperature, for
example, the co~parator 128 can provide such a reading.
In the mammography it is possible to detect the tumor mass
and also the contrast with respect to surrounding tissue.
Mammography defines the location, size and structure of a
tumor. On the other hand with regard to the use of microwaYe
energy for detection, what can be detècted is actual thermal
activity generally independent of size of the tumor. It i8
expected that this detection of thermal activity actually
precedes the $ormation of mass and thus may give an early
indication of the intended growth of a cancerous tumor. It is
also noted that the antenna placements in accordance with the
invention are preferably provided so that comparisons can be
rnade between detection~ in accordance with the present
invention and detections can be made by the presently used
mammography techniques.
Having now described a limited number of embodiments of the
present invention, it should now be apparent to those skilled
in the art that numerous other embodiments and modifications
thereof are contemplated as falling within the scope of the
present invention as defined by the appended claims. For
example, there i~ described herein~ antennae in the form of
waveguide members. These antennae can be air filled as well as
dielectrically filled. They may be provided with only a
-37-
``` ~1.291Z~O
dielectric window at the end of the waveguide. Furthermore,
the waveguide ty~e antenna may be replaced by a printed antenna
construction.
What is claimed is:
-38-
.
: .. , - .
