Method and apparatus for detecting cancerous tissue using luminescence excitation spectra

A method and apparatus for detecting the presence of cancerous tissue using native visible luminescence. The tissue to be examined is excited with a beam of monochromatic light that causes the tissue to fluoresce over a spectrum of wavelengths. The intensity at which the excited tissue fluoresces can be measured either over a spectrum or at a predetermined number of preselected wavelengths. By determining the wavelength(s) at which maximum intensity(ies) are attained for the tissue in question and by comparing these peak wavelengths, either visually or electronically, to the peak wavelength(s) derived from a known non-cancerous tissue, or by comparing the luminescence spectrum of the excited tissue with the luminescence spectrum of a known noncancerous tissue and/or known cancerous tissue or the excitation spectra of the excited tissue with the excitation spectra of known cancerous and/or known non-cancerous tissue one can determine the carcinomatoid status of the tissue in question. Once it has been determined that the tissue is cancerous, it may by destroyed by ablation by exposing it to a beam of light from a high power laser. The invention is based on the discovery that the visible luminescence spectra for cancerous and non-cancerous tissue are substantially different and that the differences are such that visible luminescence from tissue can be used to detect the presence of cancer and also on the discovery spectral profiles of excitation spectra are similarly different.

BACKGROUND OF THE INVENTION 
The present invention relates to a method and apparatus for detecting the 
presence of cancerous tissue and more particularly to a method and 
apparatus for detecting cancerous tissue using native visible 
luminescence. 
Because a sufficiently effective method has not yet been developed to 
prevent cancer, cancer research has focused on the most effective ways to 
cure an organism that is diagnosed as having a cancer. As different as the 
various forms of treatment have been--ranging from excision to radiation 
to chemotherapy--all treatments have relied on one crucial step, detection 
of the cancerous tissue. The importance of detection cannot be stressed 
enough. Early detection not only indicates the presence of a cancer but 
also may give an indication as to where the cancer originated and as to 
what type of treatment will be the most safe and effective method. Early 
detection can provide such benefits because it reveals the state of 
maturation of the cancer cell. Cancer cells are clonal cells of a single 
"founder" cell that is the result of some mutation of the normal cell for 
the particular tissue. As a result of the mutation, the founder cell 
replicates and divides, eventually forming a mass of cells called a tumor. 
Tumors are harmful to an organism because they proliferate at a metabolic 
rate that exceeds that of the normal neighboring cells. As a result, the 
tumor grows at the expense of the normal neighboring tissue, ultimately 
destroying the normal tissue. One of the reasons why it is so difficult to 
completely cure an organism of cancer is that cancer cells have the 
ability to disseminate throughout the organism via lymphatic or 
circulatory systems and to create new tumors where they arrive. However, 
this ability to disseminate comes only to those cells that have lost the 
characteristic membrane glycoproteins of the mutated tissue. For this 
reason, it takes a while before cancer can spread. An advantage to early 
detection is that the cells can be examined for characteristic properties 
such as cell size and shape to determine the source of the cancer cells. 
Clearly, the importance of an accurate technique that can be utilized in 
vivo or in vitro cannot be minimized. The advantage of an in vivo and in 
vitro technique is that sensitive tissue may be tested, relatively 
undisturbed, for example, with the use of an inserted optical fiber probe. 
Presently, the diagnosis of cancer mainly relies on X-rays, nuclear 
magnetic resonance, nuclear radiation or invasive methods based on 
chemical laboratory analysis and biopsy. In view of the dangerous side 
effects of X-rays, nuclear radiation, and biopses it appears that a 
definite need exists for a new technique for detecting cancer which can 
either eliminate or reduce the necessity of X-rays, nuclear radiation, and 
biopsies. 
Although there exist many effective methods for detecting cancer, very few 
methods are based exclusively on the intrinsic properties of the cell and, 
as a result, interfere with normal tissues. For example, Hematoporphyrin 
derivative (HPD), which absorbs preferentially to cancerous tissue, is 
currently employed as a photosensitizer of tumors for photoradiation 
therapy. Unfortunately HPD interfers with normal tissue and does not make 
a good in vivo technique for detection. Flavins and porphyrin found in 
abundance for their effectiveness at transferring electrons in subcellular 
organelles known as mitochrondria are known to fluoresce in the visible 
light portion of the luminescence spectra. 
Optical spectroscopy and laser technology offer new possible techniques for 
detection and characterization of physical and chemical changes which 
occur in diseased tissue, either invivo or invitro. This lends itself to a 
new approval for diagnosis of pathological changes in tissue. 
The present invention is based, at least in part, on the discovery that the 
fluorescence spectra profile of cancerous tissue is different from the 
fluorescence spectra profile of normal tissue, the discovery that the 
fluorescence peak is blue-shifted (shifted to lower wavelengths) and in 
other samples red-shifted (shifted to longer wavelengths) in areas 
corresponding to flavin and porphyrin peaks and that the red peaks are 
reduced in intensity. Because this blue-shift (or red-shift) in the 
fluorescence spectra is an intrinsic property of the tissue, normal tissue 
is unaffected, making the monitoring of these fluorescence spectra an 
especially safe in vivo technique. A possible explanation for the 
blue-shift (or red-shift) and change in fluorescence spectral profile of 
cancerous tissue is that the flavins and porphyrins are in different 
environments that effect the fluorescence of these molecules. Flavins 
maybe blue-shifted (or red-shifted) when a protein closely associated to 
the flavin acquires net positive (blue-shift) or negative (red-shift) 
charge relative to its native state. Porphyrins, which fluoresce only in 
cancerous tissue are probably in the dissociated state since this is the 
only form that fluoresces. The abundance of free porphyrins in cancerous 
tissue may result from a reduction of the metal ion that serves to build 
the porphyrins in the proteins. Self absorption by hemoglobin molecules 
may cause the complex profile in normal tissue. 
The discovery that certain biological molecules fluoresce differently in 
cancerous and non-cancerous tissue and that spectral changes in shape and 
shift to the blue (or red) for these molecules present a sufficient 
criteria for determination of cancerous tissue. 
The present invention is also based in part of the discovery that the 
excitation spectra are different for normal and cancerous tissue. 
In U.S. Pat. No. 2,437,916 to W. F. Greenwald there is described a 
technique for examining living tissue which involves illuminating the 
tissue with a beam of light and then measuring the intensity of the 
reflected light at certain wavelengths ranges using a phototube and 
different colored filters. 
In U.S. Pat. No. 3,674,008 to C. C. Johnson there is described an 
instrument which quantitatively measures optical density of a 
transilluminated body portion. The instrument comprises a controllable, 
relatively low-frequency oscillator generating pulses which are applied to 
a light source through a first expand and delay circuit. A 
light-conducting source to one side of the body portion and a similar 
means optically couples another side of the body portion to a light 
detector. Alternatively, the light source and detector may be placed 
directly on the body portion. After compensation for ambient light, the 
output of the detector is coupled to a sample and hold circuit which is 
triggered by the controllable oscillator through a second expand and delay 
circuit. The stored signal in the sample and hold circuit is proportional 
to transmittance and calibrated display means. Methods of using the 
instrument in diagnosis are discussed, as are further applications to 
spectrophotometeric determinations. 
In U.S. Pat. No. 3,963,019 to R. S. Quandt there is described a method and 
apparatus for detecting changes in body chemistry, for example, glycemia, 
in which a beam of light is projected into and through the aqueous humor 
of the patient's eye. An analyzer positioned to detect the beam on its 
exit from the patient's eye compares the effect the aqueous humor has on 
said beam against a norm. An excess or deficiency of glucose present in 
the aqueous humor produces a corresponding positive or negative variation 
in the exiting beam and thereby indicates a hyper or hypo glycemia 
condition in the body chemistry of the patent being tested. 
In U.S. Pat. No. 4,029,085 to D. P DeWitt et al there is described a method 
for determining the bilirubin concentration in the blood serum of a person 
from measurement of the spectral reflectance of the skin. The disclosed 
method detects the severity of jaundice, common neonatal condition, and 
enables determination of the type of treatment regimen needed to prevent 
the billirubin level from becoming sufficiently high to cause kernicterus 
which can result in brain damage. The method includes measuring the 
reflectance of the skin within a predetermined frequency spectrum, and 
more particularly, at a number of specific wavelengths in the visible 
portion of the spectrum. 
In U.S. Pat. No. 4,290,433 to Robert R. Alfano there is described a method 
and apparatus for detecting the presence of caries in human teeth using 
visible luminescence. A region to be examined is excited with a beam of 
monochromatic light. The intensity of the visible light emitted from the 
region is measured at two predetermined wavelengths, one where the 
intensity dependence of the spectra is about the same for caries and non 
caries and the other where the relative intensity changes significantly in 
the presence of caries. A signal corresponding to the difference in the 
two intensities is obtained and then displayed. By first determining the 
magnitude of the difference signal at a nondecayed region, any increases 
in the magnitude as other regions are probed on the discovery that the 
visible luminescence spectra for decayed and nondecayed regions of a human 
tooth are substantially different and that the differences are such that 
visible luminescence from teeth can be used to detect the presence of 
caries. 
In Medical and Biological Engineering, Vol 6, No 4 August, 1968, pp. 
409-413 there is described a technique for tissue identification during 
needle puncture by reflection spectrophotometry. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a new, rapid, and improved 
technique for detecting the presence of cancerous tissue. 
It is another object of the invention to provide a technique for detecting 
the presence of cancerous tissue which does not involve the use of X-rays. 
It is still another object of this invention to provide a technique for 
detecting the presence of cancerous tissue that does not involve the use 
of other potentially harmful radiation, such as ultraviolet radiation or 
nuclear radiation. 
It is yet still another object of this invention to provide a technique for 
detecting the presence of cancerous tissue of a person which is reliable, 
rapid, inexpensive and easy to use. 
It is another object of this invention to provide a technique for detecting 
the presence of cancerous tissue which does not require the use of X-ray 
sensitive plates or film. 
It is yet still another object of this invention to provide a technique for 
detecting the presence of cancerous tissue using visible light as an 
exciting source and native visible luminescence to probe for the cancerous 
tissue. 
It is still another object of this invention to provide a technique for 
detecting the presence of cancerous tissue using excitation spectra to 
distinguish cancerous from normal tissue; 
It is still another object of this invention to provide a new diagnostic 
tool for the pathologist to evaluate a biopsy in cancer and for a surgeon 
to evaluate if all cancerous tissue has been removed, using fluorescence 
spectroscopy. 
It is a further object of this invention to provide a new diagnostic tool 
for the pathologist to evaluate a biopsy in cancer and for a surgeon to 
evaluate if all cancerous tissue has been removed, using fluorescence 
spectroscopy using excitation spectroscopy. 
It is still another object of this invention to provide a in-vivo 
spectroscopy diagnosis technique using an optical fiber (endoscopy) to 
determine cancer inside a body (i.e. stomach, lungs, urinary tract, 
intestinal tract, brain, colon, eye and throat). 
It is still another object of this invention to provide a in-vitro 
spectroscopy diagnostic technique for a pathologist to test biopsy 
samples. 
It is another object of this invention to provide a technique for detecting 
and then destroying cancerous tissue. 
It is a further object of this invention to provide a new and improved 
technique for determining if tissue is cancerous or normal. 
The present invention is based on the discovery that the shape of the 
native visible luminescence spectra from normal and cancerous tissue are 
substantially different, and in particular, that for cancerous tissue 
there is a shift to the blue (or red) with different intensity peaks and 
also on the discovery that the excitation spectra for native normal tissue 
and cancerous tissue are different. 
The method for detecting the presence of cancerous tissue involves, 
according to one embodiment of the invention, illuminating a region to be 
examined with a beam of monochromatic light, and then determining if the 
resulting luminescence spectrum more closely represents the luminescence 
spectrum for a cancerous tissue than the luminescence spectrum for a 
normal tissue. The determining can be achieved by comparing the resulting 
luminescence spectrum either (1) with a luminescence spectrum for normal 
tissue and observing how it differs or (2) with a luminescence spectrum 
for cancerous tissue and observing how it differs or (3) with a 
luminescence spectrum for cancerous tissue and with a luminescence 
spectrum for normal tissue and observing which of the two spectra it more 
closely represents. In another embodiment excitation spectra are compared, 
rather than luminescence spectra the excitation spectra being obtained by 
varying the excitation wavelength and then detecting the intensity at a 
preselected wavelength where luminescence occurs. 
The apparatus for detecting the presence of cancerous tissue according to 
one embodiment of the invention includes a monochromatic light source, a 
spectrograph, a fiber optics (endoscope) a video camera, a digitizer, a 
computer and a display. 
The apparatus for detecting the presence of cancerous tissue according to 
another embodiment of the invention includes a monochromatic light source 
whose wavelength is variable, a spectrometer, and a light detector. 
In still another feature of the invention, a high power laser is provided 
for destroying the cancerous tissue by ablation, after it has been 
detected. 
The foregoing and other objects and advantages will appear from the 
description to follow. In the description, reference is made to the 
accompanying drawing which forms a part thereof, and in which is shown by 
way of illustration specific embodiments for practicing the invention. 
These embodiments will be described in sufficient detail to enable those 
skilled in the art to practice the invention, and it is to be understood 
that other embodiments may be utilized and that structural changes may be 
made without departing from the scope of the invention. The following 
detailed description is therefore, not to be taken in a limiting sense, 
and the scope of the present invention is best defined by the appended 
claims.

DETAILED DESCRIPTION 
As used herein, the term "tumor" means cancerous. 
The present invention is directed to a method and apparatus for detecting 
the presence of cancerous tissue using native visible luminescence. 
An experimental arrangement used to measure the luminescence spectra from 
the various tissues is shown in FIG. 1. A 10 mw Argon ion laser 1 
operating a 488 nm was focused on the front surface of the tissue 2 to a 
spot size of about 100 .mu.m. The native luminescence from the front 
surface was collected into a double SPEX-1/2 m grating scanning 
spectrometer 3 blazed at 500 nm. A photomultiplier tube (PMT) RCA 7265 
(S-20) 4 located at the exit slit of the spectrometer 3 measured the 
intensity at different wavelengths. The spectral bandwidth was 1.8 nm. The 
output of the PMT was connected to a Princeton Applied Research lock-in 
recorder combination 5 to display the spectrum. Both the laser and 
reference signal from light 7 and detected by a PMT 6 were chopped at 200 
Hz. The spectra were not corrected for the spectrum response of the 
system. Each sample emission spectrum was run three times for 
reproducibility. The measured spectra were stable in time and different 
regions yielded similar spectra. 
The luminescence emitted from cancerous and normal tissues from rat 
prostate and kidney were investigated. The spectra from a rat female 
bladder tumor and a mouse bladder tumor were also measured. All tumors 
were subcutaneously implanted. Rat prostate tumors were implanted in 
Fischer/Copenhagen male (f.sub.1) rats and were five weeks old at the time 
of the testing. Rat kidney tumors were implanted in Wistor/Lewis rats and 
were four weeks old. Rat bladder tumor was implanted in a female Fischer 
rat and was four weeks old at the time of testing. Mouse bladder tumor was 
implanted in a female C3HHe mouse and was also four weeks old. All tissue 
samples were nonnectrotic, clean free and approximately 1 gm in weight. 
All tissue samples were solid chunks but not cut to any particular 
specificity, and were few millimeters thick. Each tissue sample was placed 
in a clean pyrex test tube for these luminescence studies. 
The spectral curves for the cancerous and normal tissues are displayed in 
FIGS. 2-4. One notices the differences in the spectra between the normal 
and cancerous tissues. The prominent maxima in the spectra from rat 
prostate tumor [FIG. 2(a)] and rat normal prostate [FIG. 2(b)] are located 
at 521 and 533.5 nm., respectively. The prostate tumor spectrum has two 
subsidiary maxims located at 552 and 593 nm while no additional maxima are 
recorded in the normal prostrate spectrum. In the prostate tumor spectrum 
there are four points of inflections located at 538.3, 571.7, 587.0, and 
619.5 nm. On the decreasing side of the normal prostate curve there are 
two points of inflection located at 571.7 and 603.3 nm, as shown in FIG. 
2(b). 
The main maxima in the spectra from male rat kidney tumor [FIG. 3(a)] and 
normal male rat kidney [FIG. 3(b)] are also located at 522.0 and 530.6 
nm., respectively. After the first prominent peak, the spectrum from the 
rat kidney tumor decreases monotonically and there are three small peaks 
located at 592, 612, and 638 nm. Along this declining side of the curve 
there are four inflectionary points located at 548.7, 559.3, 581.3, and 
604.2 nm. However, after the first prominent peak for the normal male 
kidney, the spectrum declines monotonically until it reaches a wavelength 
at 590.8 nm where it starts to increase. Along the declined portion of the 
curve there are three smaller peaks located at 562, 600 and 622 nm. The 
spectrum also contains three inflectionary points located at 522 and 595 
nm. Similar spectral differences have been observed in human tissues of 
the lung and breast. 
The salient features of the rat bladder tumor spectrum are its four peaks. 
[FIG. 4(a)]. The first prominent peak is located at 519.1 nm; other 
smaller peaks are located at 554, 590, and 634 nm. The spectrum also 
contains two inflectionary points locate at 567.0 and 605.2 nm. After the 
minimum at 614.7 nm the curve starts rising to the last peak at 634.0 nm, 
after which there is a fall off to zero intensity. 
The salient features of the mouses bladder tumor spectrum are its two wide 
peaks [see FIG. 4(b)]. The first prominent peak is located at 521.0 nm, 
and the other at 600.0 nm. The spectrum starts declining from 610 to 648 
nm after which its slope changes and decays slowly to zero. There are two 
points of inflection in the spectrum, one located at 559.2 nm and the 
other at 648.2 nm. 
The summary of the results from the fluorescence measurements shows the 
following salient features that are found in common among the tumor 
spectra: 
1. Location of the prominent maxima of the tumor spectra all occur at about 
521.0 nm. 
2. The width of the prominent maxima are virtually the same, approximately 
spanning 1.5 nm. 
3. Secondary peaks which are in common to all tumors occur between 590-640 
nm. 
4. The secondary peak which is also in common with the rat prostate tumor 
and the rat bladder tumor is in the range of 552-554 nm. 
5. The secondary peak which is also in common with the rat kidney tumor and 
the rat bladder tumor fall in the range of 634-638 nm. 
Upon analysis of the data between the two normal spectra, one recognizes 
the prominent maxima are located at 530-533 nm and the width of the 
prominent maxima are broad, each spanning 38 nm. 
The most salient differences between the cancerous and the normal tissues 
are that the spectral profiles are very different and that the cancerous 
prominent maxima are shifted and located around 521 nm, whereas the 
prominent maxima of the normal tissues spectra are located at about 531 
nm. 
As can be seen, when protein containing fluorphors either gain positive 
charge ions or lose negative charge ions the fluorescence from the 
fluorphors have been noted to be blue shifted. The prominent maxima of all 
cancerous spectra exhibit in our results a 10 nm blue shift, suggesting an 
accumulation of positive ions, or a depletion of negative (or positive) 
ions in the mitochrondria of cancerous cells, thus causing the flavins to 
emit at 521 nm instead of 531 nm. 
The emission from 590-640 nm is attributed to porphyrins. In cancerous 
tissue the relative intensity of porphyrins bands are different, usually 
smaller in intensity from its normal counterpart. The spectral changes can 
be caused by other species such as hemoglobin. Similar differences have 
been observed in human lung and breast tissues. 
Referring now to FIG. 5. there is illustrated an embodiment of an apparatus 
for detecting cancerous tissue according to the teachings of this 
invention. 
The apparatus includes a source 11 of white light, such as a 
tungsten-halogen filament lamp, and a narrow band filter 13. 
Alternatively, source 11 may comprise a laser. Light source 11 has power 
coupled to it from a conventional power supply (not shown). Narrow band 
filter 13 has a bandwidth of less than about 30 nm and preferably less 
than about 10 nm and is designed to pass light at a wavelength .sub.1. 
Light from source 11 that is passed by filter 13 is passed through a 
chopper 14 which removes any ambient light present and is then fed into an 
input leg 15 of a fiber optic probe 17. The light entering fiber optic 
probe 17 emerges at the probing end 19 and impinges on tissue Ts to be 
tested. Light from tissue Ts enters probing end 19 and is conducted out of 
fiber optic probe 17 through output legs 21, 23, and 24, which are located 
at the same end as input leg. 15. 
Alternatively, the light from tissue Ts can be imaged into a spectrograph 
or optical filters coupled to a video silicon intensified target camera 
computer for displaying the entire spectra. The light can be collected and 
imaged using a lens or a fiber optic bundle into a video camera. 
Fiber optic probe 17 is made up basically of a bundle of optical fibers. 
The diameter of the bundle is preferably about 1/2 to 5 nm. The fibers 
within the bundle are preferably randomly arranged to reduce any 
geometrical collection effects. Fiber optic probe 17 may include a lens or 
lens system (not shown) at the probing end 19 so that non-contact probing 
may be achieved. 
Light emerging from output leg 21 is passed through a narrow band filter 25 
having a bandwidth of less than about 10 nm, and designed to pass light at 
a wavelength .lambda..sub.2, and impinges on a photodetector 27. Light 
emerging from output leg 23 is passed through a narrow band filter 29 
having a bandwidth of less than about 10 nm and designed to pass light at 
a wavelength .lambda..sub.3, and impinges on photodetector 31. Light 
emerging from output leg 24 is passed through narrow band filter 30 having 
a bandwidth of less than 10 nm and designed to pass light of wave-length 
.lambda..sub.4 and impinges on photodetector 32. 
The value of .lambda..sub.1 is between 350 and 500 nanometers. 
Photodetectors 27, 31 and 32 are conventional photodetectors having 
maximum sensitivity in the regions of interest, namely at wavelengths 
.lambda..sub.2 and .lambda..sub.3 and .lambda..sub.4 respectively of the 
fluorescence spectra. 
The wavelengths are chosen where the largest difference in intensity occurs 
for cancerous and normal tissues, i.e. .lambda..sub.2 =531 nm, 
.lambda..sub.3 =522 nm, .lambda..sub.4 =633 nm. By using more detectors at 
more wavelengths one can more accurately determine differences in the 
spectra. Comparing the entire spectra using video spectroscopy such as 
shown in FIG. 7 results in a more accurate way to find cancer. 
Photodetectors 27, 31 and 32 each produce an electrical signal output whose 
magnitude S1, S2 and S3 respectively, is proportional to the intensity of 
the incident light. The electrical output signals from photodetectors 27, 
31 and 32 are each fed into an electronic circuit 33 which produces three 
output signals S4, S5 and S6, one corresponding to the ratio of S1 and S3 
and the third corresponding to the ratio of S2 to S3, another 
corresponding to the ratio of S1 and S2. The three output signals are fed 
into a display where they are displayed 34. The difference in the signals 
(i.e. the difference between signals S1 and S2 or S2 and S3) could also be 
used and compared. 
Light source 11, narrow band filters 13, 25, 29 and 30 and photodetectors 
27, 31 and 32 are preferably all situated in a light-tight comparmented 
housing 37. 
In detecting the presence of cancerous tissue in accordance with this 
embodiment of the invention, the ratios of the three probe signals S1, S2 
and S3 are first determined for a known noncancerous region for the 
particular organ containing the tissue under test. Any changes in the 
ratios between signals S1 and S2 and S3 will indicate that the tissue is 
cancerous. 
Instead of taking the ratios between signals S1 and S2 and S3, the 
differences or ratios of any two as opposed to three signals, such as S1 
and S2 may be used to determine the relative change of the spectra. This 
may be achieved using any conventional type of difference circuit for 
differences or a divider circuit for ratios. 
Referring now to FIG. 6, there is illustrated a simplified diagram of 
another embodiment 102 of the invention. Monochromatic light from a source 
101 is transmitted by a fiber optic probe 103 for a sample tissue ST6 to 
be tested. Light from the sample tissue ST6 is transmitted by fiber optic 
probe 103 to a spectrograph (i.e. dual zero dispersion) 105 constructed so 
as to detect native luminescence emitted light from the sample tissue ST6. 
The output of the spectrograph 105 is imaged by a video camera 107 whose 
output is fed through a digitizer 109 into a computer 111. The spectrum of 
emitted light along with a spectrum of emitted light for a normal tissue 
(for the particular organ in question) are both displayed on a display 
(such as a TV monitor). The difference in spectra is obtained by a 
computer and then displayed to determine if the tissue is cancerous. 
In FIG. 7 there is shown another embodiment 110 of the invention. Light 
from a source 111 is passed through a narrow band filter 113 where it is 
transmitted by a fiber optic probe 115 to the tissue ST7 to be tested. 
Native luminescence emitted from tissue ST7 is imaged by a lens 117 
through a filter wheel 119 having two or more filters where it is imaged 
on the eye 121. Instead of a filter wheel and eye, the light from lens 117 
may be imaged onto the slit of a spectrograph (i.e. dual zero dispersion) 
and then processed as in the FIG. 6 embodiment. 
In FIG. 8 there is shown another apparatus constructed according to this 
invention, the apparatus being identified by reference numeral 131. 
Apparatus 131 includes a first laser 133 whose output beam is used to 
detect the cancerous tissue and a second laser 135 whose output beam is 
used to destroy the cancerous tissue after it has been detected as will 
hereinafter be described. Laser 133 is a low or medium power laser such as 
an argon laser or a helium-cadmium laser. Laser 135 is a high power laser 
such as a Q-switched laser, a copper vapor laser, a gold vapor laser, a 
nitrogen laser or a dye laser. 
Light from laser 133 is transmitted by an optical fiber bundle 137 to a 
filter 139 which filters out all light but the preselected wavelength. 
Light passed by filter 139 is transmitted by an optical fiber bundle 141 
to a dichroic coupler 143 which is designed to transmit light from laser 
133 and reflect light from laser 135. Light transmitted through coupler 
143 from laser 133 is transmitted by an optical fiber bundle 145 to a 
beamsplitting coupler 147. Light transmitted through coupler 147 from 
coupler 143 is transmitted by an optical fiber bundle 149 to a beam 
splitting coupler 151. Light transmitted through beamsplitting coupler 151 
is transmitted by an optical fiber bundle 153 which functions as an 
endoscope and strikes sample tissue ST8 which is being examined. 
Light subsequently emitted from sample ST8 (i.e. the native luminescent 
radiation) and striking bundle 153 is transmitted back to beamsplitting 
coupler 151 where it is reflected to an optical fiber bundle 155 which 
transmits the light to a spectrograph 157. The output of spectrograph 157 
is imaged by a video camera 159. The output of video camera 159 is fed 
through a digitizer 160 into a computer 161 where it is compared with a 
spectrum of emitted light for a normal tissue to see if the tissue is 
cancerous. 
The results obtained in computer 161 (i.e. the difference in spectra) are 
displayed in a display 163. If the results are positive, computer 161 
sends a signal to activate laser 135. Light from laser 135 is transmitted 
through fiber bundle 169 to coupler 143 and is then reflected by coupler 
143 through bundle 145, coupler 147, bundle 149, coupler 151 and endoscope 
153 where it strikes sample ST8 and destroys the cancerous tissue by 
ablation. 
A vacuum pump (not shown) can be used to draw out the cancerous tissue 
fragments. 
Apparatus 131 also includes a lamp 171 for illuminating the area being 
examined (or treated) at an appropriate time, so that it can be visually 
observed through an eyepiece 173 by a person such as a doctor. Light from 
lamp 171 is fed into coupler 147 through a fiber bundle 175, a filter 177, 
a fiber bundle 179, a beamsplitter 181 and a fiber bundle 183. From 
coupler 147 the light is fed into endoscope 153. The illuminated area is 
viewed through eyepiece 173 which is coupled to beamsplitter 181 through 
optical fiber bundle 187. 
Instead of comparing the spectrum obtained with a spectrum for normal 
tissue the spectrum could be compared with a spectrum for known cancerous 
tissue and the differences displayed. 
Also, instead of simply displaying differences, the spectra themselves can 
be displayed and the decision made by the viewer as to whether it is 
cancerous. 
In another arrangement the spectrum obtained is compared with spectra for 
normal and for cancerous tissue and a determination made as to which of 
the two spectra the sample spectrum more closely represents. 
In another embodiment of the invention, excitation spectra are generated 
and used for detecting the presence of cancerous tissue in a similar 
manner as the luminescense spectra. The excitation spectra are obtained by 
measuring the intensity of the native luminescence at a preselected 
emission wavelength as the excitation wavelength is varied. 
Excitation spectroscopy provides information on which bands are responsible 
for the observed spectroscopic differences. Experimental results have 
shown that the differences in the excitation spectra for the normal and 
cancerous tissues are pronounced. 
An apparatus 201 for obtaining excitation spectra and also for destroying 
the tissue examined if desired if it is cancerous is shown in FIG. 9. The 
apparatus includes means 203 for illuminating a sample ST9 with a beam of 
monochromatic light whose wavelength is varied and means 205 for measuring 
the intensity of emitted light at a preselected wavelength. Apparatus 201 
is similar to apparatus 131, the differences being that laser 133 is 
replaced by a light source 207, a spectrometer 209 and a chopper 211 and 
the spectrograph 157 and video camera 158 are replaced by a spectrometer 
213, a photodetector such as a photomultipler tube 215, an optical fiber 
bundle 217 and a lock-in amplifier 219. Light source 207 is a source of 
white light and may be for example a tungsten-halogen lamp. In using 
apparatus 201, light from source 207 is chopped and fed into spectrometer 
209. The output of spectrometer 209 is transmitted through the various 
beamsplitters and optical fiber bundles and strikes sample ST9. The 
wavelength of the output of spectrometer 209 is varied by turning a knob 
(not shown) or scanning with a motor in spectrometer 209. The intensity of 
the emitted light is fed into spectrometer 213 whose output is detected by 
detector 215. The output of detector 215 is fed into lock-in amplifier 219 
whose output is fed into computer 161. The excitation spectra so obtained 
is then compared with excitation spectra for normal and/or cancerous 
tissue and a determination made if the tissue is cancerous based on the 
comparison. Instead of a lock-in amplifier 219, a dc meter could be 
employed. The light emitted from spectrometer 209 is monochromatic and 
varied over a range of wavelengths. Accordingly, means 205 measures the 
intensity of emitted light at a preselected wavelength as the excitation 
wavelength is varied. Laser 135 is used to destroy to tissue if it is 
deemed desirable. 
Spectrometer 213 can be replaced by an appropriate filter, if desired. 
Experimental apparatus used to obtain excitation spectra from a sample 
native human breast tissues was a Perkin-Elmer LS-5 Fluorescence 
Spectrometer. Frontal excitation was used to pump the tissue samples. The 
excitation spectra were scanned from 300 nm to 500 nm for an emission peak 
at 520 nm, from 300 nm to 530 nm for an emission peak at 550 nm and from 
300 nm to 580 nm for an emission peak at 600 nm. The emission peaks were 
chosen to be 520 nm, 550 nm, and 600 nm because these peaks are prominent 
in the emission spectra of the native breast tissues. 
The tissue samples were put in plastic square cells which did not generate 
strong background in the excitation spectrum region from 300 nm to 580 nm 
after ND filters were placed in the emission spectrum path to reduce 
emission. Three pairs of human breast normal and tumor (cancerous) tissues 
were measured. The excitation spectrum profiles were consistent with each 
other. 
Typical excitation spectra from native normal and tumor (cancerous) human 
breast tissues emitted at 520 nm, 550 nm, and 600 nm are shown in FIGS. 10 
through 15. One notices that the excitation spectrum profiles are quite 
different from the normal and tumor tissues. 
The excitation spectra consists of two wide bands, centered in the 
ultraviolet (uv) and visible. The uv band of the excitation spectra for 
the normal breast tissues in FIG. 10 and FIG. 12 consist of three sharp 
peaks located at 336 nm, 352 nm, and 371 nm. The major peak is centered at 
352 nm. However, there are no clear sharp peaks in the uv bands of the 
excitation spectra of cancer tissues. In FIG. 11 and FIG. 13 a very small 
peak at 352 nm can be observed. The cancer spectra are broader with a 
characteristic feature existing at 396 nm. The main peak in the visible 
band of the excitation spectra in FIG. 10 and FIG. 12 for normal tissues 
is located at 473 nm. The intensities of the visible band are about four 
times weaker than the uv bands. However, for the tumor breast tissues in 
FIG. 11 and FIG. 13, the intensities of the visible bands are higher than 
the uv bands. 
The excitation spectra for emission wavelength at 600 nm for normal and 
tumor tissues are shown in FIG. 14 and FIG. 15. The larger difference 
between the structures in the excitation spectra for normal and tumor 
tissues can be easily noticed. Structures exist in uv spectra for normal 
tissue while a broad band with a peak at 396 nm exists for cancer tissues. 
A visible band at 473 nm exists in both spectra. The intensity differences 
for the excitation spectra of tumor tissues from normal tissues are 
displayed in the table in FIG. 16 for emissions at 520 nm, 550 nm, and 600 
nm. The ratios between the excitation intensities for tumor and normal 
tissues can serve as a diagnostic marker. 
The excitation spectra in the uv band from normal tissues consist of three 
peaks while the tumor excitation spectra are without much distinct peaks. 
The uv band of the tumor excitation spectra are much wider than the uv 
band of the normal tissues due to the existence of the 396 nm peak. We 
should point out that the broad spectrum and the peak at 396 nm may be a 
characteristic of cancer in the excitation spectra which may be used to 
distinguish cancer from normal tissues. These differences suggest that the 
electronic states of fluorophores are altered in cancer cells in 
comparison to those molecules in the normal cells. 
The visible bands of the excitation spectra show clear differences in the 
electronic band centered at 473 nm for the excitation spectra intensity. 
The intensity of the tumor tissue for 520 nm is 5.38 times larger at 457.9 
nm and 2.59 times larger at 488 nm than for the normal tissues. The 
excitation spectrum intensity for 550 nm is 5.16 times stronger at 457.9 
nm and 3.53 times stronger at 488 nm that that of the normal tissues. 
However, the differences are much weaker for uv. These results support the 
fact that the cancer fluorescence emission spectra are different and 
stronger than normal tissue spectra for 488 nm excitation and only 
slightly different for uv excitation. Thus, excitation spectroscopy can be 
used as a diagnostic tool for the detection of pathological changes in 
tissues. 
In the FIG. 6 embodiment the fiber optic bundle could be replaced by a 
microscope for microscopic analysis of normal and cancerous tissue. Also 
in FIG. 9 the photodetector 215 could be replaced by a video system. 
The embodiments of the present invention is intended to be merely exemplary 
and those skilled in the art shall be able to make numerous variations and 
modifications to it without departing from the spirit of the present 
invention. All such variations and modifications are intended to be within 
the scope of the present invention as defined in the appended claims.