Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
6~3~
., ,
., The present invention relates to a device and
, method for the quan~itative measur2ment of the absorption,
.
-2
refraction, and scatter, as a function of wavelength, of
biological tissue, especially living human tissue, utili~ing
non-ionizing radiation.
li i
Present methods of interrogating human tissue to
detect the internal structure underlying the tissue have employedl
various x-ray, computerized axial tomographic x-ray, thermographic,
and ultrasonic wave techniques. While x-rays yield good images
of internal body structure, they rely on ionizing radiation which
entails a carcinogenic risk to the patient. This risk is of
special importance in the detection of breast lesions. Wholly
apart from the radiation dosimetry risks associated with the
use of x-rays, the utilization of x-rays is inefficient from
an energy standpoint. More specifically in this connection,
a conventional x-ray tube consists of an anode-and-cathode
assembly placed in an evacuated glass envelope. The anode is
usually a massive piece of copper in which is placed a small
tungsten target. The cathode assembly generally consists of a
~ilament of tungsten wire placed in a shallow focusing cup. I -
The hot tungsten filament provides the source cf electrons
which are accelerated toward the anode by applying a high voltage
between the anode and cathode. Even in the most favorable cases,
the active radiation output of such an assem~ly is one or two
percent of the total electron energy. In other words, most
of the ener~y is dissipated in the target 2S collisional energy
or heat. In addition to the foregoing shortcomings of x-ray
techniques in tissue interrogation, proper shielding and direction
of an x-ray beam -~ith the use of a diaphragm and ports are
required to obtain a usable film exposure or a satisfactory
treatment.
. I
i' .
.,
36~.
--3
The use of thermographic techniques in the inter-
li rogation of human tissue while employing non-invasive infrared
energy has a number of shortcomings which make it unsatisfactory
I as a diagnostic tool, particularly in the case of human breast
1, lesions. In the case of breast lesion detection, thermography,
¦ alone, generally is not relied upon, and is usually supplemented
and used in conjunction with mammography. One reason for using
I x-ray techniqùes along with thermographic practices to detect
breast lesions centers on the problem of maintaining a machine
employing thermographic techniques sufficiently stable for
quantitative and reproducible measurements. The large gain
in the amplification required in converting the radiant infrared
energy into a display makes the system ~ery susceptible and
sensitive to system drift. The slight drift in the sensitivity
of the detector will result in a change in the intensity of
, the display with respect to the temperature of the s~lrface
¦ being scanned~ Wholly apart from the aforementioned problem,
! it is required to use a coolant such as liquid nitrogen to
I maintain the temperature of the radiant energy detector within
usable temperature ranges. This aspect of the technique
entails the use of substantial amounts of energy to sustain
a temperature of -198-C, the temperature at which nitrogen
is in a liquid state. Thermography has the further disadvantage
of being unable to detect and locate small lesions in the thick
living tissuesuchas the human breast. In this connection,
¦l insufficient infrared radiation is emitted by such small bodies
¦ to enable the infrared sensing unit of such equipment to detect
i' any appreciable change in tissue temperature caused by such
'!
, small bodies.
Ultrasonic techniques are limited in application
. .
.,
9ti3~
,
by attenuation and interaction of ultrasound waves wi~h the
tissue being interrogated. In addition, ultrasound poses certain ~
biological hazards such as platelet aggregation which is exhibitea
at power levels less than those causing thermal injury.
In accordance with the present invention, apparatus
!~
and a method have been evolved for the non-invasive examination
of living human tissue which effectively eliminates the hazards
involved in the use of x-ray and ultrasonic techniques, and which
overcomes the problems inherent in the use of thermographic
diagnostic techniques. The present invention is directed to
the quantitative measurement of visible and infrared light
transmission and reflection, and involves passing light of
various selected wavelengths through tissue being studied and
measuring the intensity of light transmitted or reflected relative
to the intensity of the light sent thus enabling a measurement
of the refractive index, absorption, and scatter of the tissue.
The invention takes advantage of the fact that various types
of tissues such as fat, muscle and tumor differ significantly in
absorption, refraction, and scattering characteristics with
respect to visible and infrared light. The contrast elicited-
between various tissues can be increased by selecting the
wavelengths used for measurement. Information regarding t~ssue
type and metabolic state can be obtained by measuring the amount
of light trans~itted or reflected at various wavelengths, and
comparing these values with norms or standards previously
established by direct measurement in human patients who sub-
sequently have biopsy documentation of the nature of the tissue
examined. In one of its forms, the device of the present in- i
vention utilizes a detec-tor array to di~ferentially record the
I, .
9~1
. . ,
,i I
-5
photon flux in the central area which corresponds to that portion
of the detector which is maximally illuminated by the light beam
when tissue is not interposed to serve as scattering medium, and
one or more concentric rings of active detector surface whlch
receive light which has been scattered to various degrees away
from the central detector. This arrangement allows separate
recording of central and peripheral zones thereby providing
additional information regarding intensity of scattering as
well as the degree of refraction and absorption at that particular
wavelength. Information from each of these concentric detectors
is recorded separately and is available for further manipulation !
such as the creation of ratios. In its simplest form, this
embodiment of the invention comprises a central detector of the
dimensions of the unscattered beam and one or more concentric
peripheral detectors. An alternative embodiment is an electronic
detector array of multiple elements such that a tissue-scatter-
signature map may be produced which is specific to transillumina-'
tion of water, blood, fat, muscle, breast cancer, skin, flecks
of calcium, and other simple and complex transillumination
elements. Such complex tissue signatures can be stored in
digital or analog memory and can be comp-~red with freshly
received signals. Changes in the scatter ratios can be used
as a signal in imaging and non-imaging systems. I
In accordance with another aspect of this invention,
scanning quantitative transmission or reflection of visible or
infrared light to produce a shadowgraph imase is employed. In
this form of the invention, the above-described quantitative
transmission or reflection system is sequentially scanned across
the tissue being investigated to build up an image in a point-wise
.. ..
'~
9~3
` I
~j I
-6
, fashion. The scanning advantageously is carried out by conven-
I tional rectilinear techniques utilizing a photo-exposure device
mechanically coupled to the light source and detector unit.
Alternatively, photographic recording can be obtained by elec-
' tronically coupling the XY position of the scanning arm with
il the XY location of the electron beam of a cathode ray tube
l in connection with time exposure of the photographic film. In
¦I such -n electronic configuration the XY position of the beam
is determined by the XY position of the scanning head and the
intensity of the electron beam current is proportional to the
number of photons sensed by the detector head.
'.1 ~
¦~ A still further aspect of the invention involves
¦¦ the quantitative transmission and reflection of visible and
¦ infrared light at specific wavelengths to emphasize the dis-
j tinction between various tissues in conjunction with a digital
¦ memory or an image storage tube such that image multiplication,
¦ division, addition, or subtraction can be performed in a
digital form with digital memory or in analog form on an image
storage tube. The individual images carried by various wave-
l lengths can be displayed in a multi-spectral imaging process
1, which can be displayed in a gray scale modality or in a color
Il display in which image data at a specific wavelength is assigned
¦¦ to a specific color gun in a three beam color video display.
~! Through multi-spectral processing techniques the distinction
¦ between different tissues or different components in tissue
or physiologic information such as the oxidation state of
various portions of tissues can be demonst~ated and recorded.
In an addi~ional aspect of the invention, a computer
I . ~
631
. . .
-7
aided reconstruction is utilized which is based on multiple
images each of which has been produced from a different trans-
mission or reflection light point source. The computerized
reconstruction and processing method is analogous to that used
in computerized axial tomographic systems of the type currently
employed with x-rays. The tissue under examination is illuminated
from a multiplicity of points by either moving light or an array
of switched sources. The imaged pattern formed by illumination
from each point is sensed by an appropriate detector system
such, for example, as the Hammamatsu infrared vidicon, and
processed for field uniformity correction prior to being stored
in an electronic memory. The imaged patterns are stored in
conjunction with the XY coordinates of the originating ~rans-
illumination light point. These imaged patterns are processed
by being mathematically back projected to yield a tomogra~hic
set of images. One advantage of this system is that the
spacial relationship of objects can be ascertained in depth,
and resolution is much higher with a greater photon efficiency
than can be achieved in a rectilinear scanning mode.
The apparatus of the present invention, in its
basic form, comprises a light source, light detection means,
and a signal display means. In its more sophisticated form,
the device of the present invention includes a light source,
wavelength selection means, light transmission means, optical
alignment means, light collection means, light detection means,
signal amplification means, signal comparison means and signal
display means. The term "light" as used herein means non-ionizing
visible and infrared light having a wavelength ir the range o~^
400 to about 700 nanometers, and 700 to about 106 nanometers,
. I . I
,, ,
, .
31
' I .
-8
respectively. The preferred range is from about 600 nanometers
in the visible range to about 1400 nanometers in the infrared
range.
The light sources used in the practice of the
invention include a quartz-halogen tungsten filament projector
bulb, a xenon arc lamp, a xenon-mercury arc lamp, light-emitting
diodes, tunable lasers, or ordinary light. The wavelength
selection means employed advantageously comprises broad or
narrow band thin film optical filters with peaks ranging from
about 450 nanometers through about 1350 nanometers at 50
nanometer intervals. One or more monochromators may also be
advantageously used. The light delivery or transmission means
employed include flexible fiber-optic bundles, rigid light
guides or pipes, said means being capable of transmitting the
wavelengths of interest. The detector means used include
silicon or germanium photodiodes, photomultiplier tubes, vidicons,
and the like.
The foregoing, and other features and advantages
of the invention, will become clear from the following descrip-
tion and claims taken in conjunction with the accompanying
drawings wherein:
Fig. 1 is a representation of the propagation
of light through relatively homogeneous human tissue illustrating
the effect of interaction of the light with a solid absorption
body in the tissue, the wave forms illustrated being isoluminance
lines;
Fig. 2 is similar to Fig. 1 except that .he solid
absorption body is at a greater distance from the light entry
point;
Figs. 3 and 4 are top and side ~-iews, respectively,
illustrating light entering at two different points to produce
isoluminance lines which are projected as shadow patterns in
Fig. 3;
Fig. 5 is a view in perspective of one embodiment
of the apparatus of the present invention;
Fig. 6 is a view in perspective, partly broken
away, illustrating an embodiment of a rectilinear scanner
head for practicing the present invention;
Fig. 7 is an exploded view, partly in section, of
a light delivery unit for supporting and transmitting light
through a human breast;
Figs. 8A and 8B are side and top views, respectively,
of an embodiment of apparatus utilizing a rectilinear scanner
head of the type shown in Fig. 6 in conjunction with a cathode
ray tube set up for interrogating the human breast; and
Figs. 9A and 9B are side and top views, respectively,
illustrating the light delivery unit shown in Fig. 7 used in
conjunction with computerized axial tomography apparatus for
interrogating a human breast.
At the outset, it should be mentioned that it has
been demonstrated that biological materials manifest compara-
tively good transparency in the infrared region of the spectrum
li
to permit sufficient photon transmission through human tissue
being examined to enable detection of events even in areas of sub-
stantial thickness. Thus, Frans F. ~obsis, in an article entitled
. , .
"Noninvasive, Infrared ;vlonitoring of Cerebra~ and Myocardial
., !
6~1 '
,,
1, --1 o
Oxygen Sufficiency and Circulatory Parameters" published in
Science, December 23, 1977, Volume 198, pp. 1264-1267, stated
"The relati~ely good transparency of biological materials in
the near infrared region of the spectrum permits sufficient
photon transmission through organs examined for the monitoring
of intraceIlular events.~' The Jobsis article dealt with the
monitoring of tissue oxygen sufficiency. By uti;izing strong
light sources and a photomultiplier tube, Jobsis was able to
detect infrared light traversing 13 centimeters of human brain
through the skull and scalp. I
Referring, now, more specifically to Fig. 1 of the
drawings, the propagation of visible red orinfrared light
through relatively homogenous tissue which is intensely light
scattering and which contains a light absorbing object is illus-
trated by wave iorms which shall be called isoluminance lines.
Light enters the tissue 10 at 12 as a narrow collimated mono-
chromatic beam. Isoluminance line 14a defines the outlines of
equal luminosity which have been produced by light input at
point 12. Isoluminance lines 14b and 14c represent isoluminance
line contours at increasing distances from the original light
input at point 12. Isoluminance line 14d represents the
distribution of light intensity after interaction with a light-
absorbing object 16. Isoluminance line 14e depicts the gradual
filling-in process of the shadow cast by the light-absorbing
object 16 due to intense scatter within the tissue 10. Iso-
luminance line 14f, at considerable distance from the light
input point 12 and the light-absorbing object 16, has a
shallow depression 18 in the isoluminous contour caused by the
light ~bsorption by object 16. The center of the depression
, . ,
, -- 10 -- I
lg631
18a is caused by absorption by the light-absorbing object 16
and representS a luminosity minimum, while the rim 18b of the
depression represents a luminosity maximum. A detector such
as a silicon photodiode or silicon photodiode arrav (not shown),
placed on the opposite side Oc the tissue 10 from the light
input point 12 overlying the depression 18 in the isoluminance
line 14f, enables a measurement to be made of the light trans-
mission through the tissue 10 as affected by the light-absorbing
object 16. A detector of sufficient size to have a separate
sensitive surface covering the areas 18a and 18b of the depression
18 would provide a meaningful ratio between the luminosity at
18a and 18b to enable the object 16 to be detected.
Fig. 2 is similar to Fig. 1 except ~hat the light
input point 20 is at a greater distance from the light-absorbing
object 22. As before, the light input generates a series of
isoluminance lines 24a, 24b, 24c, 24d, 24e, and 24f before
interacting with the light-absorbing object 22. Line 24g
represents the distribution of light intensity after interaction ! -
with the light-absorbing object 22. Since the light-absorbing
object 22 is close to the upper surface of the tissue 10,
the depression 26 in the isoluminance line 24h is quite large
compared to the situation depicted in Fiy. 1 in which there
was a greater distance between the object 16 and the uppar
surface of the tissue 10. In the representation of Fig. 2,
there is a greater difference between the level of lisht at
the edge 26b of the depression 26 as compared with the center
26a of the depression. Detection of the object 22 can be
achieved as described in connection with the description of ig.l.
Figs. 3 and ~ are side and top view represen~ations
~.
t;3:~
I! ;
1, .
-12
of isoluminance lines produced in a section of intensely light
scattering tissue 30, having two different light~absorbing
objects 32 and 34, when light is introduced at two points 36
and 38. The isoluminance lines emanating from point 36 are
shown in broken lines, while the isoluminance lines emanatins
from the point 38 are shown in solid lines. The lines 36a,
36b and 36c emanating from the point 36 provide, as before, a
depression 40 which is detectable as indicated at 32a in Fig. 3.
However, the isoluminance lines 36a, 36b, and 36c also fan out
laterally in the direction of the object 34 and form a depression
42 which is detectable as a shadow of the object 34 as represented
by 34' in Fig. 3. Similarly, isoluminance lines 38a, 38b, 38c,
38d, and 38e emanating from point 38 provide a detectable depres-
sion 44 as a result of the absorption of the light by the object
34. The shadow 34a thus pxoduced is detectable as represented
in Fig. 3. As in the case of the isoluminance lines emanating
from point 36, the isoluminance lines 38a, 38b, 38c, 38d, and
38e from point 38 are intercepted and absorbed by the object
32 to provide a depression 46 which is detec~able as a shadow
32' as shown in Fig. 3. Thus, it is possible not only to detect
the presence of the two objects 32 and 34 in the tissue 30,
but, also, to precisely pinpoint the areas in the tissue 3
where they are located, by back projection means.
The embodiment of the apparatus of the present
invention illustrated in Fig. 5 comprises a light source and
wavelength selection member 50 connected by a flexible fiber- !
optic bundle or light guide 52 to a photosensor carrying member
54 which, in turn, is connected by a cable 56 to a digital
photometer readout member 58. The light source and wavelength
,. I
1, ~
- 12 -
.
3631
-13
selection member 50 includes a housing 50a in which a source of
infrared light such as 2 quartz halogen tungsten lamp (not
shown) is positioned. A variable intensity control knob 50c
l is provided on the housing 50a for controlling the intensity of
¦I the beam emitted by the lamp. A filter wheel 60 is rotatably
jl mounted on the housing 50a by a shaft 50b. The wheel 60 desirably
i comprises a plurality of concentrically arranged broad band,
thin film interference filters 60a each advantageously having a
different peak ranging from 450 nanometers to 1350 nanometers
at 50 nanometer intervals. Narrow band filters may be employed
to further discriminate among processes detected with the
¦ apparatus. The entrance facet 52a of the fiber-optic light
¦I guide 52 is maintained in position with respect to the lamp
and a selected one of the filters 60a by a collar 62 joined to
¦ a standard 64 attached to the base of the housing 50a.
i
The photosensor carrying member 54 as illustrated
comprises a short, stationary end post 54a and a long, stationary
end post 54b ~aintained in fixed, spaced apart relation by a
pair of smooth surfaced rods 54c-54c and an externally threaded
rod 54d having an adjusting knob 54j. A movable post 54e
is positioned between the posts 54a and 54b, ar.d is adjustable
in either direction on the rods 54c-54c and 54d by turning the
knob 54j. A suitably scaled measuring device 54f is secured
at its ends to the stationary posts 54a and 54b. An indicator
54g is secured to the movable post 54e, and is adapted to
slide along the markinss on the device 54f as the post 54e is
moved. The outlet end of the fiber-optic light guide 52 passes
through a bore in the outer end of the movable post 54e, and is
secured in a disc 66. A set screw 68 maintains the outlet end l -
- 13 -
i3~
of the guide 52 in position with relation to the post 54e. The
long s.ationary post 54b has an adjustable head 54h whlch
carries a photosensor in the form of a solid-state photodetector
70 of the silicon photodiode type. The head 54h is provided
with a knurled adjusting screw 54i to enable the photodetector
70 to be aligned with the outlet end of the fiber-optic light
guide 52. The input cable 56 connects the photodetector 70 to
the digital photometer readout member 58. The member 58 has
¦! selection buttons 58a for determining the display factors which
are visible through a window positioned over a liquid crystal
display 58b.
In utilizing the apparatus shown in Fig. 5, a
human breast having a palpable lump is comfortably compressed
! between the clisc 66 and the photodetector 70. The measuring
! device 54f will indicate the exact distance between the outlet
end of the light guide 52 and the photodetector 70y and, there-
fore, the thicknes~ of the tissue being traversed by the light
from the source located in the housing 50a. Readings are
obtained on the readout member 58 by passing light, at different
wavelengths, from the source through the lump in the breast.
Using the same wavelengths, light from the source is then
passed through an area, or areas, of the breast away from the
lump. Since the degree of light scattering and absorption
at specific wavelengths by a cancerous body is far greater
i than that of benign bodies and healthy, fatty tissue, the nature
of the palpable lump can readily be ascertained from the in-
formation displayed by the readout member 58.
i~Referring, now, to Fig. 6 oE the dr~wings, the
1. i
1 - 14 -
f-~6'3~
-15
embodiment of the rectilinear scanner head illustrated, and
designated generally by reference numeral 80, comprises a lower,
stationary portion 80a and an upper movable portion 80b which is
vertically adjustable with relation to the portion 80a. The
portions 80a and 80b at one end define a pair of parallel plate
members 82 and 84 between which a human breast to be examined is
compressed. The lower portion 80a of the scanner head 80 is
provided with a housing 80c in which is positioned a source
of infrared light such as a quartz halogenbulb 86 associated
with a re1ector 88. A rotatable filtèr wheel 90 is mounted
on a shaft above the bulb 86 and the reflector 88. The wheel
90, like the wheel 60 of the apparatus shown in ~ig. 5, is
designed to house a plurality of concentrically arranged narrow
or broad band optical filters 90a in cavities along its perimeter.
An area of the wheel 90 extends through a recess or slot formed
in the rear wall of the scanner to enable an operator to readily
select any desired filter 90a for tissue interrogation purposes.
Light from the bulb 86 passes through a selected filter 90a and
enters the entrance end of a flexible fiber-optic bundle 92
held in position on the housing 80c by a fitting 80d. The
exit end of the optic bundle 92 is secured in a coupling 94a
positioned on the upper end of a post 94. The coupling 94a also
receives the entrance facet of a rigid light pipe 96 which
slides in an alignment member 98 and s~hich terminates at the
lower or breast engaging surface 84 of the adjustable upper
plate member 80b of the scanner head 80. The exit facet 96a
of the light pipe 96 advantageously is provided with a variable
aperture (~ot shown) to enahle the diameter of the light beam
traversing the optic bundle 92 and the light pipe 96 to be
regulated at the exit facet 96a of the light pipe 96. Positioned
- 15 -
1. 1
631
, . .
-16
,i .
below and in oppos~d relation to the exit facet 96a of the ligh~
pipe 96 is a photoreceptor 100 provided with a variable aperture
lOOa for controlling the diameter of the light beam entering
the photoreceptor 100. The photoreceptor 100 desirably is a
silicon photodiode and is mounted on the end of an alignment
shaft 102. The shaft 102 passes through a bore in an alignment
member 104 and is received in an integral coupling 94b provided
at the lower end of the post 94. The coupling 94b is secured to
an internally grooved sleeve 106 which receives an externally
grooved drive shaft 108. The shaft 108 is driven by a motor
104a carried by the alignment member 104, and is grooved to form
a combined cloc~wise and counterclockwise helix such that, upon
completion of its travel in either direction along the drive
shaft 108, the sleeve 106 will automatically reverse its direc-
tion of travel. As the shaft 108 rotates, the post 94, the light
pipe 96 and the photoreceptor 100 are simultaneously moved in
the same direction of travel as the post 94 assembly. At each
fore and aft travel end point, an escapement or switch (not showr.).
moves the light pipe 96, shaft 102, and alignment members 98 !i
and 104, a precise amount on the slide guides 114-116, through
an indexing rotation of the gears llOa-llOa on the gear tracks
112-112. Each end of.the gear shaft 110 is provided with a
gear llOa-llOa which travel ontheparallely arranged gear tracks
112-112. Thus, a two dimensional surface can be interrogated
by the fore and aft, and lateral travel of the exit facet 96a
of the light pipe 96 and photoreceptor 100 in response to the
motion of the drive shaft 108 and the gear shaft 110.
i
The breast engaging surfaces of the plate members
82 and 84 desirably are formed of a clear plastic to enable
the exit facet 96a of the light pipe 96 and the variable aperture
, - 16 -
9~31
-17
100a on the photoreceptor 100 to move with relation to the
breast without making direct contact with it.
,¦ Alignment of the movable elements ofthehead 80
is maintained by the aligned parallely arranged tracks 114
Il and 116, respectively. The entire upper portion 80b of the
¦I scanning head 80 can be moved vertically relative to the lower
portion 80a so as to accept substantially any size breast. The
post 94 and the shaft 110 are splined to allow free up and down
movement from a distance of about one inch to four inches. A
¦ manually driven toothed power transmission belt 120 is connected
¦I to height adjustment screws (not shown) positioned at the
corners of the scanning head 80 to enable the space between
the clear plastic surfaces of the members 82 and 84 to be adjusted
as desired. A shaft 122 is provided for connecting the scanning
head 80 to a scanning console 130 ~see ~igs. 8A and 8B). A
cable 124 carries two sets of electronic signals to the imaging
console 132. One set of signals relates to the absolute inten-
sity of light sensed by the photoreceptor 100. The other set
of signals relates to the absolute XY positional coordinates of
the light pipe exit facet 96a and the photoreceptor variable
aperture 100a. These sets of electronic signals provide
intensity modulation to a CRT beam and location control to that
beam. As shown in Figs. 8A and 8B, the breast of a patlent 134
is compressed in the scanning head 80 which is connected by the
shaft 122 to a support column 130a. An operator 136 communicates
by a keyboard 138 with the control electronics 140 to produce
¦ an image and alpha-numeric display on cathode ray tube 142. Images
i on photographic film are produced by a multiformat imager 144.
- 17 -
I, ,
3t;31
!1
-18
In Fig. 7 of the drawings, there is shown a light trans-
llmitting apparatus comprising a base member 150 and a breast
,'supporting member 152. The member 150 carries a light source
'such as a quartz halogen bulb (not shown) positioned in a
reflector 154. A fiiter wheel 156 is ro-tatably mounted above
the reflector 15g and is provided with a plurality of optical
filters 156a concentrically arranged around the perimeter thereof.
~A portion of the outer margin of the wheel 156 extends outwardly
through a slot 150a formed in the side wall of the member to
~facilitate rotation of the wheel. A light pipe 158 having a
¦ lightentrancefacet positioned ad~acent to the filter wheel
¦~156 in opposed relation to the light source is carried in the
!I member 150. The light pipe 158 is branched to provide two
¦llight exit facets 158a and 158b which are shuttered by a toothed
¦¦aperture wheel 160. The light pipe 158, its light exit facets
158a and 158b, and the aperture wheel 160 rotate about a hollow
shaft 162 driven by a belt 164 connected to a drive disc 166
and a motor 168. The member 152 is provided with a downwardly
¦extending rod 152d which is received in the hollow shaft 162
of the member 150. The member 152 is contoured to enable a
patient to be comfortably examined~ The upper surface 152a
of the member 152 has a plurality of evenly spaced llght point
apertures or orifices 152b formed Lherein. Each of the orifices
152b is aligned with the light exit facets 170a of an equal
! number of fiber-optic light delivery bundles 170. The light
¦ entrance facets 170b are arranged adjacent spaced rows of
¦¦openings 152c formed in the bottom surface of the member 152.
IIn operation, the llght exit facets 158a and 158b of the light
', pipe 158, and the apertured wheel 170 are rotated in a manner
such that the outer and inner rows of openings 152c, and their
,
- 18 -
~9~3~
Il -19
;lassociated light entrance facets 170b of the optic bundles 170,
¦lare addressed sequentially. A timing signal from the motor 168
¦lis fed to a computerized axial tomographic apparatus 180 tsee
Figs. 9A and 9B).
¦ As shown in Figs. 9A and 9B, a patient 182 is seated
with her left breast compressed between the upper surface 152A~
¦ of the member 152 and a light excluding cone 184. The computer-
¦¦ized axial tomographic apparatus schematically illustrated
¦¦comprises image receptor means ~hich includes a computer com-
¦¦patible tv camera 186. A yoke 188 maintains optical alignment.
IjA shaft 190 allows rotation about the axis and vertical movemer.t
¦is possible along a support column 192. An operator 194
manipulates a keyboard 196 for communicating ~ith the computer
and to display images and alpha-numerics on a cathode ray tube.
Computer system 200 consists of several modules including a
yideo analog-digital converter 202, a camera-computer interface
204, and a frame storage unit 206. ~he frames 208 are operated
upon by a uniformity connection module 210, and are passed to
frame memory 212. When the family of images coded to the light
points from exit facets 170a of the member 152 have been acquired,¦
an image reconstruction algorithm 214 operates upon these frames
to create a computer reconstructed back projected image. This
image is displayed on a television imase display monitor 216,
and is simultaneously displayed on a high resolution video screen
of a multiformat film imager 218 which serves to produce
! transparency images of the breast on the member 152 similar
lin appearance to con~entional mammogra~s.
I ~ .
I
' 19
l!
31
-20
,~ ~1hile the invention has been disclosed and described
with relation to its utilization in the detection of human breast
lesions, it should be understood tha~ the invention can also be
used to monitor the changing optical absorption and scatter
Ijcharacteristics of light in the lungs and other accessible tissues'.
¦Iand to image lungs and brain as well as other portions of t~ie body;
