Abstract:
The present invention utilizes a series of optical and electronic elements to detect and image cancerous and/or pre-cancerous cells in living tissue. The invention further uses the images thus obtained to adaptively and dynamically shape a treatment light beam so as to maximize the beam&#39;s intensity in proportion to the areas with the most cancer or pre-cancer and to minimize the irradiation of normal tissue by the beam.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority of U. S. Provisional Application 60/356,302 filed on Feb. 12, 2002, which is incorporated by reference herein, and of U. S. Provisional Application 60/363,997 filed on Mar. 14, 2002, also incorporated by reference herein. 
     
    
     
       BACKGROUND  
         [0002]    This invention relates to detection and treatment systems for cancer and pre-cancer, and more specifically to a detection and treatment system that first detects cancerous and pre-cancerous tissue in situ, and then dynamically and automatically shapes and re-shapes its photodynamic therapy (PDT) treatment beam during the course of treatment to maximize the effect of the treatment beam while simultaneously minimizing the illumination of surrounding normal tissue.  
           [0003]    Analyzing living cells using fluorescence of a dye, which is produced in an interaction between tissue and an injected chemical, is a well-understood method in the field of medical science. In this method of analysis, a chemical is introduced into living tissue, where the chemical is preferentially absorbed into cancerous or pre-cancerous cells. The chemical interacts with the living tissue to produce a dye. The dye is highly fluorescent, meaning that it absorbs a particular wavelength of light, and subsequently emits a longer wavelength of light. For example, a dye might absorb 340 nm light very well, and as a result of absorbing such light, will immediately emit large quantities of light in a band centered at 530 nm. Thus, many methods exist that involve introducing a drug into living tissue (either intravenously or topically), waiting for the drug to be interact with the tissue and produce a dye and to be preferentially absorbed by cancerous and pre-cancerous cells, and then illuminating an area of the tissue with 340 nm (ultraviolet) light, while simultaneously receiving light from the area with a detector that is sensitive only to 530 nm light (using a filter, for example, that allows only 530 nm light to pass through to the detector).  
           [0004]    Another method for analyzing living cells involves looking at a series of narrow-wavelength-bands of reflected light from the tissue. In this process, broad-wavelength light (for example, white light spanning the range from 400 nm to 700 nm) is used to illuminate the sample. A high-resolution multispectral imager is then used to image the tissue at several different wavelength bands. With this method, it is possible to find locations where larger-than-normal densities of capillary blood vessels occur. The presence of larger-than-normal densities of capillary blood vessels (along with their shape, in some cases) may indicate the presence of cancerous and/or pre-cancerous cells.  
           [0005]    Analyzing living cells using autofluorescence spectroscopy is also well understood in the field of medical science. In the process of autofluorescence no drug is introduced to the living tissue. Light of a particular wavelength is simply introduced to the living tissue, and through the process of autofluorescence, light of a longer wavelength is immediately emitted from the same tissue. Compared to the process of fluorescence of a dye, which is produced in an interaction of tissue with an injected drug (described above), the process of autofluorescence produces a great deal less emitted light. In addition, all living cells will emit light from naturally occurring flurophores within the cells.  
           [0006]    Thus, the detection of emitted light, and especially the discrimination between light emitted from normal cells and that emitted from cancerous or pre-cancerous cells, becomes a difficult, two-part problem to solve. First, the fluorescence light must be efficiently detected and then the detected light must be processed with complex computer algorithms to discriminate between normal and cancerous/pre-cancerous cells. There are solutions to the problem in the prior art, most of these using spectroscopy or multispectral imaging. For example, U.S. Pat. No. 6,208,749, which is hereby incorporated by reference in its entirety, utilizes a filter wheel to provide images in at least three spectral bands, analyzes and characterizes each image, where the characteristics are useful in discriminating between normal and cancerous/pre-cancerous cells. The method presented in U.S. Pat. No. 6,208,749 does not obtain images simultaneously and does not provide a method for treatment of pre-cancer or cancerous cells. In U.S. Pat. Nos. 5,115,137 and 4,786,813, both of which are hereby incorporated by reference in their entirety, systems are described that utilize filters to segment the image into four images at separate spectral bands. Since the image is divided by filtering and detection, only a portion of the image is observed in each spectral band. Again, these methods do not provide a means of treatment for pre-cancer or cancerous cells.  
           [0007]    In U. S. Pat. No. 6,135,965, Spectroscopic Detection of Cervical Precancer Using Radial Basis Function Networks, also hereby incorporated by reference in its entirety, the fluorescence spectra from a fiber optic fluorimeter at three excitation wavelengths are used to train a neural network for the detection of cervical pre-cancer. The neural network can then be used for detection of cervical pre-cancer. The method of U.S. Pat. No. 6,135,965 is non-imaging, is not coaxial and does not provide a means for treatment of pre-cancer or cancerous cells. In U.S. Pat. No. 6,256,530, also hereby incorporated by reference herein in its entirety, an intensity is measured in a wavelength range and the process repeated to compare intensities of two images at a given wavelength range. This difference is used to differentiate the response of cancerous cells from that of healthy cells. The method of U.S. Pat. No. 6,256,530 is non-imaging and provides a means only for detection, not for treatment of pre-cancer or cancerous cells. In U.S. Pat. No. 5,623,932, also hereby incorporated by reference herein in its entirety, the peak intensities and selected slope measurements of fluorescence spectra are used to differentiate the response of cancerous cells from that of healthy cells. The method in U.S. Pat. No. 5,623,932 for detection is non-imaging and further does not provide a means for treatment of pre-cancer or cancerous cells.  
           [0008]    Photodynamic therapy (PDT) is a well-understood method for the treatment of cancerous and pre-cancerous conditions. In this method, a special chemical is introduced to the living tissue. This special chemical is a photo-activated drug that kills surrounding cells when it is activated with a certain wavelength of light. This special chemical is absorbed more by cancerous and pre-cancerous cells than by normal cells. However, normal cells do absorb some of the drug. Prior art descriptions of photo-dynamic therapy involve first injecting the patient with the special drug or applying the agent topically, and then bathing a large, non-descript area of the tissue with activating light. There are several implementations of treatment systems that have introduced elements to restrict or define the illumination area. In U.S. Pat. No. 5,514,127, hereby incorporated by reference in its entirety, a spatial light modulator (SLM) is used to irradiate a selected treatment area. U.S. Pat. No. 5,514,127 requires the use of an endoscope and additionally does not provide treatment simultaneously with detection. In U.S. Pat. No. 6,186,628, also hereby incorporated by reference in its entirety, an acousto-optic modulator (AOM) is used to scan the laser beam in order to customize its shape. The method in U.S. Pat. No. 6,186,628 requires scanning of the treatment beam.  
           [0009]    In all of the above systems, the detection and treatment systems are separate and do not interact. Patient comfort, cost containment and health outcomes will be improved by a system in which detection and treatment interact.  
           [0010]    It is therefore an object of this invention to detect and locate cancerous and/or pre-cancerous cells in living tissue using a multispectral imager and a comparison of the different-wavelength images and to adaptively and dynamically shape a PDT treatment beam using the images obtained with the multispectral fluorescence imager.  
         SUMMARY OF THE INVENTION  
         [0011]    The object set forth above as well as further and other objects and advantages of the present invention are accomplished by the embodiments of the invention described herein below.  
           [0012]    The present invention utilizes a series of optical and electronic elements to detect and image cancerous and/or pre-cancerous cells in living tissue using a multispectral imager. The invention further uses the images thus obtained to shape a Photo-Dynamic Therapy (PDT) light beam so as to maximize the beam&#39;s intensity to the areas with the most cancer or pre-cancer and to minimize the amount of normal tissue irradiated by the beam. An illumination source is used to illuminate the tissue sample under investigation. Emitted fluorescent light or reflected light from the tissue sample is collected with an optical system and focused onto a sensor array. Control electronics are used to analyze the images collected on the sensor array. The control electronics determine the intensity map of the illuminated region and the boundaries of any cancerous and/or pre-cancerous cells in the tissue sample under investigation. The control electronics then correspondingly control a treatment light source so that only the areas determined to be cancerous and/or pre-cancerous are illuminated with the treatment light beam, and those areas are illuminated in proportion to the amount of light received from the imager. The treatment light beam is passed through the same optical system used to collect light (through the use of a flip-down mirror or a dichroic beamsplitter) and is thus focused onto the tissue sample. After a pre-determined dose of treatment light is administered, the entire cycle is repeated until the cancerous and/or pre-cancerous cells are diminished below some pre-determined threshold value.  
           [0013]    While the present invention can be practiced with a variety of means for obtaining the multispectral image and for detecting the boundaries of the cancerous and/or pre-cancerous cells in the tissue sample under investigation, the preferred embodiment of this invention utilizes a multispectral imager in conjunction with a comparison of the different-wavelength images, to analyze living tissue using fluorescence, autofluorescence, and/or reflectance imaging. The present invention also comprises utilizing spatial information obtained from this tissue analysis to guide the shaping of a treatment beam in a PDT setup.  
           [0014]    The present invention improves patient comfort, cost containment and health outcomes by integrating the detection and treatment phases. The treatment light source is spatially-modulated (or beam-shaped) so that only the areas of tissue that are found to be cancerous or pre-cancerous (using the detection method described above) are illuminated with the activation light. The amount of illumination (and its spatial composition) is continuously adapted throughout the treatment. In addition, the treatment and detection systems of this invention are coupled, so that as any cancerous and/or pre-cancerous area is being treated by the treatment system, the area is (either simultaneously or alternately) being detected by the detection system to update not only the boundaries of the diseased region, but the entire area illuminated. As the cancerous or pre-cancerous cells die off, or as the photo-activating agent “bleaches” (non-linearly), the region of tissue that requires illumination will diminish and change shape. This diminishing and shape-changing will be detected by the detection system in real-time or near-real-time, and the shape of the beam and its intensity of activation light will automatically be changed accordingly, so that only the cancerous or pre-cancerous region is being illuminated with activation light and in proportion to the amount of disease.  
           [0015]    For a better understanding of the present invention, together with other and further objects thereof, reference is made to the accompanying drawings and detailed description and its scope will be pointed out in the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is schematic illustration of the concept of the invention;  
         [0017]    [0017]FIG. 2A is a schematic illustration of a first configuration of a first preferred embodiment of the invention;  
         [0018]    [0018]FIG. 2B is a schematic illustration of a second configuration of a first preferred embodiment of the invention;  
         [0019]    [0019]FIG. 3 is a schematic illustration of a filter wheel;  
         [0020]    [0020]FIG. 4 is a schematic illustration of a second preferred embodiment of the invention;  
         [0021]    [0021]FIG. 5 is a schematic illustration of the concept of a “quad-format” arrangement of images on an image sensor;  
         [0022]    [0022]FIG. 6 is a schematic illustration of a third preferred embodiment of the invention;  
         [0023]    [0023]FIG. 7 is a schematic illustration of a fourth preferred embodiment of the invention;  
         [0024]    [0024]FIG. 8 is a schematic illustration of the concept of a “quad-format” arrangement of three images and one dark region on an image sensor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    In the following descriptions of the present invention, the terms “light”, “optical radiation” and “electromagnetic radiation” may be used interchangeably, and these terms both include, but are not limited to, for example, ultraviolet, visible, and near-infrared electromagnetic radiation with wavelength(s) in the range from 0.3 micron to 2 microns. Similarly, the term “optical system”, as used herein, includes systems to operate on “electromagnetic radiation”, wherein such operations include, but are not limited to, directing, receiving, or filtering “electromagnetic radiation”.  
         [0026]    While the detailed description of the embodiment of the invention presented hereinbelow is given in relation to detecting and locating any cancerous and/or pre-cancerous cells in the tissue sample, it should be noted that the present invention is capable of detecting, locating and treating abnormalities in a tissue sample where such abnormalities possess optically discernable properties and respond to optical treatment. It should also be noted that a tissue sample as used herein includes living tissue.  
         [0027]    [0027]FIG. 1 shows a schematic diagram of the concept of the invention. An illumination source  10  is used to illuminate the tissue sample  12  under investigation with optical radiation  14 . Reflected and/or emitted fluorescent optical radiation  16  from the tissue sample  12  is collected with an optical system  18  and the optical radiation is focused  20  onto a sensor array  22 . Electronic signals  24  from the sensor array  22  are sent to control electronics  26 , which control electronics  26  are used to analyze the images that have been collected on the sensor array  22 . The control electronics  26  determine the boundaries of any cancerous and/or pre-cancerous cells in the tissue sample  12  under investigation and map the intensity of the imaged light. A composite image, showing the cancerous and/or pre-cancerous regions overlaid on a color image of the tissue sample is sent from the control electronics  26  to the display  28  via an electrical connection  30 . Confirmation of the cancerous and/or pre-cancerous regions in need of treatment is obtained from the user via the user input device  32 , which user input device  32  is connected to the control electronics  26  by an electronic connection  34 . The user may confirm or deny treatment, and may adjust the locations and shapes of regions to be treated. The control electronics  26  then correspondingly send electronic signals  36  to control a spatially modulated treatment light source  38  so that only the areas determined to be cancerous and/or pre-cancerous are illuminated with the treatment light beam  40  and in proportion to the amount of cancerous and/or pre-cancerous cells found previously. The treatment light beam  40  is passed through the same optical system  18  that was previously used to collect optical radiation  16  from the tissue sample  12  (through the use of a flip-down mirror or a dichroic beamsplitter). The treatment light beam  40 , in passing through the optical system  18 , is thus focused  42  onto the tissue sample  12 . After a pre-determined dose of treatment light  42  is administered to the tissue sample  12 , the entire cycle is repeated until the cancerous and/or pre-cancerous regions are diminished below some pre-determined threshold size and/or density or until the user determines that the treatment should end.  
         [0028]    [0028]FIG. 2A and FIG. 2B show schematic illustrations of two configurations of a first preferred embodiment of the invention  50 . In FIG. 2A and FIG. 2B, the numbering of the components of the first preferred embodiment of the invention  50  is consistent and only the action of the components differs between the two figures, as will be explained.  
         [0029]    The action of this first embodiment of the invention  50  is separated in two distinct phases. The first phase of the action is depicted in FIG. 2A and the second phase of the action is depicted in FIG. 2B.  
         [0030]    As shown in FIG. 2A and FIG. 28, all the components of this embodiment of the invention  50  are enclosed within and/or attached to a housing  52 . Referring to FIG. 2A, in the first phase of the action, an illumination source  54  is used to illuminate a target tissue sample  56  with optical radiation  58 . The illumination source  54  may emit optical radiation  58  of any range of wavelengths. For example, the illumination source  54  may emit ultraviolet radiation  58  in the range 340-380 nm. Or the illumination source  54  may emit white light  58  in the range 400-700 nm. Or the illumination source  54  may emit infrared radiation  58  in the range 600-900 nm. Or the illumination source  54  may emit a combination of ultraviolet, visible, and/or infrared illumination  58 . Furthermore, the various wavelength ranges of the illumination source may be switched on and off and otherwise controlled by the control electronics  60  via electrical wires  62 .  
         [0031]    Optical radiation  58  from the illumination source  54  is transmitted through a window  64  in the side of the housing  52 . Interaction of the optical radiation  58  with the target tissue sample  56  causes reflected and/or fluorescent emitted light  66  to be directed, to some degree, toward and through the window  64 . For example, if the illumination source  54  emits ultraviolet radiation  58 , then fluorescent light  66  will be emitted from the tissue sample  56 . Or if the illumination source  54  emits visible light  58 , then visible light  66  will be reflected from the tissue sample  56 . Upon passing through the window  64 , this reflected and/or fluorescent emitted light  66  is collected with an optical system  68 .  
         [0032]    In this first embodiment, the optical system  68  comprises an imaging lens system  70  and a filter wheel  72 , which filter wheel  72  itself includes several filters  74 , and to which filter wheel  72  is attached a filter wheel drive motor  76 . Control of the filter wheel drive motor  76  is maintained via electrical wires  78  connected to the control electronics  60 . The filter wheel  72  is fitted with a plurality of filters  74 . FIG. 3 shows an example wherein a filter wheel  72  is fitted with eight different filters  74 . Each filter  74  may transmit a single, narrow or broad, band of wavelengths, or a certain polarization of light, or a plurality of narrow or broad bands of wavelengths. Referring again to FIG. 2A, with any one filter  74  in place in front of the imaging lens system  70 , the optical system  68  causes the incoming reflected and/or fluorescent emitted light  66  to become filtered and subsequently focused  80  onto a sensor array  82 . Note that in this first phase of the action, the focused beam  80  passes by a flip-down mirror  84 , which flip-down mirror is rotated, via a rotating motor  86 , out of the way of the focused beam  80 . Action of the rotating motor  86  is controlled by the control electronics  60  via electrical wires  87 . Note that the range of motion of the flip-down mirror  84  is bounded by the strategic location of two rubber stop-bumpers  88 .  
         [0033]    Image information from the sensor array  82  is transmitted to the control electronics  60  via control wires  90 . As needed, the control electronics  60  cause the filter wheel  72  to rotate to the next filter  74  in a predetermined series, and the control electronics  60  cause the illumination source  54  to be switched to a different illumination waveband, and image information is again sent from the sensor array  82  to the control electronics  60 . After the complete predetermined series of filters  74  and illumination wavebands have been used in this way, the control electronics  60  are used to process the images thus obtained. Mathematical comparison of the various filtered images is used to compute the presence or absence of cancerous and/or pre-cancerous cells in the tissue sample  56 . A composite video image  92  is shown on a display screen  94 , which composite video image  92  is produced by the control electronics  60  and transmitted to the display screen  94  via electrical wires  96 . The composite video image  92  shows the locations, shapes, sizes, and the relative degrees of malignancy of any cancerous and/or pre-cancerous regions overlaid on a visual image of the tissue sample  56 .  
         [0034]    The user of the invention may interact with the control electronics  60  through the use of a user input device  98 , which user input device  98  may consist of one or more of the following: a keyboard, mouse, joystick, or any other common electronic input device. The user input device  98  is connected to the control electronics  60  via a set of electrical wires  100 . Through a combination of mathematical comparison of the various filtered images and input from the user, the control (processing/control) electronics  60  determine those regions of the tissue sample  56  that require treatment in the second phase of action. If the control electronics  60  determine that the tissue sample  56  does not require any treatment at this point, then the second phase of action is skipped, and the control electronics  60  surrender control to the user, through the use of the user input device  98 .  
         [0035]    In the second phase of action, the control electronics  60  exercise control over the remaining components of this first embodiment of the invention  50 , namely the treatment optical radiation source  102  and the treatment beam shaping mechanism  104 . The treatment light source  102  is connected to the control electronics via electrical wires  106 . The treatment beam shaping mechanism  104  is connected to the control electronics via electrical wires  108 .  
         [0036]    Referring now to FIG. 2B, in the second phase of the action, the control electronics  60  send control signals via electrical wires  62  to the illumination source  54 , thereby turning off the illumination source  54 . The control electronics  60  next send control signals via electrical wires  87  to the rotating motor  86 , thereby moving the flip-down mirror  84  into a position so as to reflect a light treatment beam  110  toward the optical system  68 , as shown in FIG. 2B. Note that the range of motion of the flip-down mirror  84  is bounded by the strategic location of two rubber stop-bumpers  88 .  
         [0037]    The control electronics  60  next send control signals via electrical wires  78  to the filter wheel drive motor  76 , thereby causing the filter wheel  72  to turn until a certain, predetermined filter  74  is rotated into place in front of the imaging lens  70  in the optical system  68 , which filter  74  is chosen so that it efficiently transmits the treatment light beam  110 .  
         [0038]    The control electronics  60  next send signals via electrical wires  108  to the treatment beam shaping mechanism  104 , thereby ensuring that when the treatment light source  102  is turned on, the shape of the treatment light beam  112  will be properly controlled by spatially-selective transmission through the beam shaping mechanism  104 . For example, the treatment beam shaping mechanism  104  may consist of a miniature Liquid Crystal Display (LCD) or Liquid Crystal Light Shutter mechanism, wherein each pixel on the mechanism may be individually turned on or off, thereby allowing or prohibiting light from transmitting through that individual pixel. The pixels of such a device would be turned on and off in such a way that only the regions of the tissue sample  56  that were determined to require light treatment will receive light treatment, and the relative amount of light treatment administered to any given area will be proportional to the amount that was determined to be needed in that area. Because the treatment beam shaping mechanism  104  is intentionally positioned at the a focal plane of the optical system  68 , it is a simple matter to turn on the pixels in the treatment beam shaping mechanism  104  that correspond to the pixels in the sensor array  82  that were found to contain images of cancerous and/or pre-cancerous tissue regions.  
         [0039]    The control electronics  60  next send signals via electrical wires  106  to the treatment light source  102 , thereby turning on the treatment light source  102  and causing treatment light  112  at a certain, predetermined power level and wavelength to be emitted in a direction toward the treatment beam shaping mechanism  104 , which treatment beam shaping mechanism  104  causes the treatment light  110  to become shaped so as to act most effectively in the treatment of cancerous and/or pre-cancerous regions of the tissue sample  56 . The shaped treatment light  110  next reflects off the flip-down mirror  84  and is thus redirected toward the optical system  68 . The imaging lens  70  and filter  74  in the optical system  68  cause the treatment beam  114  to become focused onto the tissue sample  56 . Because the treatment beam  114  was previously shaped with the treatment beam shaping mechanism  104 , the treatment beam  114  will illuminate only the regions of the tissue sample  56  that have been determined to require illumination with the treatment beam  114 . After a pre-determined amount of treatment light  112  has been shone from the treatment light source  102 , the control electronics  60  shut off the treatment light source  102 . At this point, the control electronics automatically begin the first phase of action once more.  
         [0040]    [0040]FIG. 4 shows a schematic illustration of a second preferred embodiment of the invention  200 . As shown in FIG. 4, all the components of this embodiment of the invention  200  are enclosed within and/or attached to a housing  202 .  
         [0041]    First, an illumination source  204  is used to illuminate a target tissue sample  206  with optical radiation  208 . The illumination source  204  may emit optical radiation  208  of any range of wavelengths. For example, the illumination source  204  may emit ultraviolet radiation  208  in the range 340-380 nm. Or the illumination source  204  may emit white light  208  in the range 400-700 nm. Or the illumination source  204  may emit infrared radiation  208  in the range 600-900 nm. Or the illumination source  204  may emit a combination of ultraviolet, visible, and/or infrared illumination  208 . Furthermore, the various wavelength ranges of the illumination source may be switched on and off and otherwise controlled by the control electronics  210  via electrical wires  212 .  
         [0042]    Optical radiation  208  from the illumination source  204  is transmitted through a window  214  in the side of the housing  202 . Interaction of the optical radiation  208  with the target tissue sample  206  causes reflected and/or fluorescent emitted light  216  to be directed, to some degree, toward and through the window  214 . For example, if the illumination source  214  emits ultraviolet radiation  208 , then fluorescent light  216  will be emitted from the tissue sample  206 . Or if the illumination source  204  emits visible light  208 , then visible light  216  will be reflected from the tissue sample  206 . Upon passing through the window  214 , this reflected and/or fluorescent emitted light  216  is collected with an optical system  218 .  
         [0043]    In this second embodiment, the multiple imaging optical system  218  comprises a plurality of imaging lens elements  220 , a set of filters arranged in a plane  222 , and a beam-splitting pyramid prism  224 . The exact construction and action of the multiple imaging optical system  218  may, preferably, be as described below.  
         [0044]    The multiple imaging optical system uses a series of optical elements to produce multiple simultaneous adjoining images on a single image plane. A first, intermediate, image is produced using the first telecentric imaging lens. This intermediate image is produced at a plane coincident with an adjustable-size rectangular field stop. The rectangular field stop is mounted in a sub-housing that allows its free rotation. A second telecentric lens collimates the light from the intermediate image. This collimated light is next passed through an optical splitting means, which uses the principal of refraction to separate the light into multiple components. The optical splitting means is mounted in a sub-housing that allows its free rotation. From here, the light next passes through a third and final telecentric lens, which produces a second, final, image on a single, planar detection device (such as film or a CCD array). The final image consists of a plurality of identical copies of the intermediate image, each of which may be composed of a different component, or set of components, of the original incident light. The plurality of identical copies of the intermediate image may be arranged such that their edges are adjoining or nearly-adjoining. Size of the multiple identical copies of the intermediate image may be adjusted by adjusting the size of the rectangular field stop. Orientation of the multiple identical copies of the intermediate image may be adjusted by adjusting the rotation of the rectangular field stop. Placement of the multiple identical copies of the intermediate image may be adjusted by adjusting the rotation of the optical splitting means. Further details of the optical system  218  are provided in appendix A of U.S. Provisional Application 60/356,302 and also in U.S. patent application Ser. No. 10/187,912 (filed on Jul. 2, 2002), hereby incorporated by reference.  
         [0045]    The optical system  218  acts to produce a plurality of differently filtered images of the tissue sample  206  on the sensor array  226  simultaneously. Each of the filters in the filter plane  222  may act to transmit a specific band of wavelengths and/or a specific polarization of light. For example, as shown in FIG. 5, four images  227  of the exact same region of the tissue sample  206  may be formed simultaneously on the sensor array  226 , arranged so in a so-called “quad-format”. Referring again to FIG. 4, the optical system  218  causes the incoming reflected and/or fluorescent emitted light  216  to become filtered and subsequently focused  228  into a plurality of simultaneous images on a sensor array  226 , wherein the light forming each of the simultaneous images has passed through a different filter in the filter plane  222 . One or more of these filters in the filter plane  222  may be transparent or clear. Also, one or more of these filters in the filter plane  222  may each allow only a single, narrow band of wavelengths of light to pass through. Also, one or more of these filters in the filter plane  222  may each allow only a certain polarization state of light to pass through. Also, one or more of these filters in the filter plane  222  may each allow a plurality of separate bands of wavelengths to pass through. Note that the entire filter plane  222  may be mounted on an easily-replaced fixture, for example a large filter-wheel, allowing either the user or the control electronics to exchange the set of filters in the filter plane  222  with a different set of filters, as may be required at various times in the action of the invention.  
         [0046]    The focused light  228  passes through a partial mirror  230  before being transmitted through to the sensor (detector) array  226 . Alternately, note that the partial mirror  230  may consist of a flip-down mirror, controlled by the control electronics  210 , as explained above in the first embodiment. The partial mirror (controllable transmission component)  230  may allow some or all of the focused image light  228  to pass directly through  229  to the sensor array  226 , and may cause some or all of the treatment light  232  to be reflected, as will be explained. For example, the partial mirror  230  may be a dichroic filter  230 , which dichroic filter  230  acts to allow light of certain wavelengths to pass through, and light of other wavelengths to be reflected. By using a dichroic filter  230 , it is possible to choose a waveband of light for the treatment beam  232  that is different from the band of wavelengths of light  231  that is used to form images on the sensor array  226 , thereby maximizing the effect of the dichroic filter  230 . Or the partial mirror  230  may be a polarizing beam splitter  230 , which polarizing beam splitter  230  acts to allow light of a certain linear polarization to pass through, and light of the perpendicular linear polarization to be reflected. By using a polarizing beam splitter  230 , it is possible to choose a polarization of light for the treatment beam  232  that is different from the polarization of light  231  that is used to form images on the sensor array  226 , thereby maximizing the effect of the polarizing beam splitter  230 .  
         [0047]    Image information from the sensor array  226  is transmitted to the control electronics  210  via control wires  234 . The control electronics  210  are used to process the images thus obtained. Mathematical comparison of the various filtered images is used to compute the presence or absence of cancerous and/or pre-cancerous cells in the tissue sample  206  and the relative degree of dysplasia (pre-cancer) or cancer. A composite video image  236  is shown on a display screen  238 , which composite video image  236  is produced by the control electronics  210  and transmitted to the display screen  238  via electrical wires  240 . The composite video image  236  shows the locations, shapes, sizes, and the relative degrees of malignancy of any cancerous and/or pre-cancerous regions overlaid on a visual image of the tissue sample  206 .  
         [0048]    The user of the invention may interact with the control electronics  210  through the use of a user input device  242 , which user input device  242  may consist of one or more of the following: a keyboard, mouse, joystick, or any other common electronic input device. The user input device  242  is connected to the control electronics  210  via a set of electrical wires  244 . Through a combination of mathematical comparison of the various filtered images and input from the user, the control electronics  210  determine those regions of the tissue sample  206  that require treatment and in what proportion. If the control electronics  210  determine that the tissue sample  206  does not require any treatment at this point, then the control electronics  210  surrender control to the user, through the use of the user input device  242 , and further action of this embodiment of the invention  200  is ceased.  
         [0049]    The control electronics  210  next send signals via electrical wires  246  to the treatment beam shaping mechanism  248 , thereby ensuring that when the treatment light source  250  is turned on, the shape of the treatment light beam  252  will be properly controlled by spatially-selective reflection from the beam shaping mechanism  248 . For example, the treatment beam shaping mechanism  248  may consist of a miniature Digital Light Processor (DLP) or micro-mirror array mechanism, wherein each pixel on the mechanism consists of a tiny micro-mirror, which micro-mirror may be individually turned on or off, thereby allowing or prohibiting a small portion of the treatment light  252  from reflecting in a direction that allows it to be re-imaged with the optical system  218 . The pixels of such a device would be turned on and off in such a way that only the regions of the tissue sample  206  that were determined to require light treatment will receive light treatment and in proportion to the intensity map. Because the treatment beam shaping mechanism  248  is intentionally positioned at a focal plane of the optical system  218 , it is a simple matter to turn on the pixels in the treatment beam shaping mechanism  248  that correspond to the pixels in the sensor array  226  that were found to contain images of cancerous and/or pre-cancerous tissue regions.  
         [0050]    The control electronics  210  next send signals via electrical wires  254  to the treatment light source  250 , thereby turning on the treatment light source  250  and causing treatment light  252  at a certain, predetermined power level and wavelength to be emitted in a direction toward the treatment beam shaping mechanism  248 , which treatment beam shaping mechanism  248  causes the treatment light  252  to become shaped so as to act most effectively in the treatment of cancerous and/or pre-cancerous regions of the tissue sample  206 . The shaped treatment light  232  next reflects off the partial mirror  230  and is thus redirected toward the optical system  218 . The imaging lenses  220 , the filter plane  222 , and the splitting prism  224  in the optical system  218  cause the treatment beam  256  to become focused onto the tissue sample  206 . Because the treatment beam  256  was previously shaped with the treatment beam shaping mechanism  248 , the treatment beam  256  will illuminate only the regions of the tissue sample  206  that have been determined to require illumination with the treatment beam  256 . After a pre-determined amount of treatment light  252  has been shone from the treatment light source  250 , the control electronics  210  shut off the treatment light source  250 . At this point, the control electronics automatically begin the entire series of action once more.  
         [0051]    [0051]FIG. 6 shows a schematic illustration of a third preferred embodiment of the invention  300 . As shown in FIG. 6, all the components of this embodiment of the invention  300  are enclosed within and/or attached to a housing  302 . This third embodiment acts in two separate and distinct phases, which two phases are herein called detection phase and treatment phase. In the normal course of action, the detection phase of action is performed prior to the treatment phase.  
         [0052]    In the detection phase of action, an illumination source  304  is used to illuminate a target tissue sample  306  with optical radiation  308 . The illumination source  304  may emit optical radiation  308  of any range of wavelengths. For example, the illumination source  304  may emit ultraviolet radiation  308  in the range 340-380 nm. Alternatively, the illumination source  304  may emit white light  308  in the range 400-700 nm. The illumination source  304  may also emit infrared radiation  308  in the range 600-900 nm. Or alternatively, the illumination source  304  may emit a combination of ultraviolet, visible, and/or infrared illumination  308 . Furthermore, the various wavelength ranges of the illumination source may be switched on and off and otherwise controlled by the control electronics  310  via electrical wires  312 .  
         [0053]    Optical radiation  308  from the illumination source  304  is transmitted through a window  314  in the side of the housing  302 . Interaction of the optical radiation  308  with the target tissue sample  306  causes reflected and/or fluorescent emitted light  316  to be directed, to some degree, toward and through the window  314 . For example, if the illumination source  304  emits ultraviolet radiation  308 , then fluorescent light  316  will be emitted from the tissue sample  306 . Or if the illumination source  304  emits visible light  308 , then visible light  316  will be reflected from the tissue sample  306 . Upon passing through the window  314 , this reflected and/or fluorescent emitted light  316  is transmitted through the partial mirror  330 , and this transmitted light  331  is then collected with an optical system  318 .  
         [0054]    In this third embodiment, the multiple imaging optical system  318  comprises a plurality of imaging lens elements  320 , a set of filters arranged in a plane  322 , and a beam-splitting pyramid prism  324 . The exact construction and action of the multiple imaging optical system  318  may be substantially the same as that of optical imaging system  218 . The optical system  318  acts to produce a plurality of differently filtered images of the tissue sample  306  on the sensor array  326  simultaneously. Each of the filters in the filter plane  322  may act to transmit a specific band of wavelengths or a specific polarization of light. For example, as shown in FIG. 5, four images  227  of the exact same region of the tissue sample  306  may be formed simultaneously on the sensor array  326 , arranged in a so-called “quad-format”. Referring again to FIG. 6, the optical system  318  causes the incoming reflected and/or fluorescent emitted light  316  to become filtered and subsequently focused  328  into a plurality of simultaneous images on a sensor array  326 , wherein the light forming each of the simultaneous images has passed through a different filter in the filter plane  322 . One or more of these filters in the filter plane  322  may be transparent or clear. Also, one or more of these filters in the filter plane  322  may each allow only a certain polarization state of light to pass through. Also, one or more of these filters in the filter plane  322  may each allow only a single, narrow band of wavelengths of light to pass through. Also, one or more of these filters in the filter plane  322  may each allow a plurality of separate bands of wavelengths to pass through. Note that the entire filter plane  322  may be mounted on an easily-replaced fixture, such as a filter-wheel, allowing either the user or the control electronics  310  to exchange the set of filters in the filter plane  322  with a different set of filters, as may be required at various times in the action of the invention.  
         [0055]    The incoming reflected and/or fluorescent emitted light  316  passes through a partial mirror  330  before being transmitted  331  through to the optical system  318 . Note that the partial mirror  330  may consist of a flip-down mirror, controlled by the control electronics  310 , as explained above in the first embodiment. Alternatively, the partial mirror  330  may allow some or all of the incoming reflected and/or fluorescent emitted light  316  to pass directly through  331  to the sensor array  326 , and may cause some or all of the treatment light  332  to be reflected, as will be explained. For example, the partial mirror  330  may be a dichroic filter  330 , which dichroic filter  330  acts to allow light of certain wavelengths to pass through, and light of other wavelengths to be reflected. By using a dichroic filter  330 , it is possible to choose a waveband of light for the treatment beam  332  that is different from the band of wavelengths of light  331  that is used to form images on the sensor array  326 , thereby maximizing the effect of the dichroic filter  330 . Or the partial mirror  330  may be a polarizing beam splitter  330 , which polarizing beam splitter  330  acts to allow light of a certain linear polarization to pass through, and light of the perpendicular linear polarization to be reflected. By using a polarizing beam splitter  330 , it is possible to choose a polarization of light for the treatment beam  332  that is different from the polarization of light  331  that is used to form images on the sensor array  326 , thereby maximizing the effect of the polarizing beam splitter  330 .  
         [0056]    Image information from the sensor array  326  is transmitted to the control electronics  310  via control wires  334 . The control electronics  310  process the images thus obtained. The control electronics  310  use mathematical comparison of the various filtered images to compute the presence or absence of cancerous and/or pre-cancerous cells and the relative degree of dysplasia (pre-cancer) or cancer in the tissue sample  306 . A composite video image  336  is shown on a display screen  338 , which composite video image  336  is produced by the control electronics  310  and is transmitted to the display screen  338  via electrical wires  340 . The composite video image  336  shows the locations, shapes, sizes, and the relative degrees of malignancy of any cancerous and/or pre-cancerous regions overlaid on a visual image of the tissue sample  306 .  
         [0057]    At this point, control of the treatment procedure may be passed to the user, who would decide whether to continue with treatment of the tissue. If the user decides that treatment is indicated, then the user would initiate the second phase of action of the invention. This second phase of action is called the treatment phase.  
         [0058]    The first step of the treatment phase involves the user applying a photosensitizing drug (also called a porphyrin) to the patient. This photosensitizing drug may be applied intravenously or topically. Examples of photosensitizing drugs include Photofrin® and delta- or δ-amino levulinic acid (ALA). The user next allows the drug sufficient time to be absorbed into the cells of the tissue, before the treatment phase continues.  
         [0059]    The control electronics  310  send signals via electrical wires  312  to the illumination source  304 , thereby causing the tissue sample  306  to be illuminated with white light  308 . Reflected light  316  from the tissue sample  306  passes through  331  the partial mirror  330  and enters the optical system  318 . The optical system  318  focuses the light  328  onto the sensor array  326 . The image information is transferred electronically through an electrical connection  334  from the sensor array  328  to the control electronics  310 . This visible reflected image is processed and stored by the control electronics  310 . The control electronics  310  shut off the white-light illumination source  304 .  
         [0060]    At this point, the filter plane  322  in the optical system  318  may be changed by the user or by the control electronics  310 , thereby introducing into the filter plane  322  a different set of filters.  
         [0061]    The control electronics  310  next send signals via electrical wires  346  to the treatment beam shaping mechanism  348 , thereby ensuring that the treatment light beam  352  will be uniformly reflected from the treatment beam shaping mechanism  348 .  
         [0062]    The control electronics  310  next send signals via electrical wires  354  to the treatment light source  350 . The treatment light source is thereby caused to emit low-power light  352  at a certain band of wavelengths such that the photosensitizing drug in the tissue sample  306  will emit fluorescent light  316  but will not be significantly photoactivated. Treatment light  352  from the treatment light source  350  reflects off the treatment beam shaping mechanism  348 . This reflected light beam  332  is collimated by the imaging lens  358 , and the collimated treatment beam  356  reflects off the partial mirror  330 . The collimated treatment beam  356  next passes through the window  314  and is incident upon the tissue sample  306 .  
         [0063]    Interaction of this low-power treatment beam  356  with the photosensitizing drug in the target tissue sample  306  causes reflected and/or fluorescent emitted light  316  to be directed, to some degree, toward and through the window  314 . Upon passing through the window  314 , this reflected and/or fluorescent emitted light  316  is transmitted through the partial mirror  330 , and this transmitted light  331  is then collected with an optical system  318 .  
         [0064]    The optical system  318  causes the incoming reflected and/or fluorescent emitted light  331  to become filtered and subsequently focused  328  into a plurality of simultaneous images on a sensor array  326 , wherein the light forming each of the simultaneous images has passed through a different filter in the filter plane  322 . One or more of these filters in the filter plane  322  may be transparent or clear. Also, one or more of these filters in the filter plane  322  may each allow only a certain polarization state of light to pass through. Also, one or more of these filters in the filter plane  322  may each allow only a single, narrow band of wavelengths of light to pass through. Also, one or more of these filters in the filter plane  322  may each allow a plurality of separate bands of wavelengths to pass through. Note that the entire filter plane  322  may be mounted on an easily-replaced fixture, allowing either the user or the control electronics to exchange the set of filters in the filter plane  322  with a different set of filters, as may be required at various times in the action of the invention.  
         [0065]    Image information from the sensor array  326  is transmitted to the control electronics  310  via control wires  334 . The control electronics  310  are used to process the images thus obtained. Mathematical comparison of the most-recently captured various filtered images is used to compute the presence or absence of cancerous and/or pre-cancerous cells in the tissue sample  306  and the relative degree of dysplasia (pre-cancer) or cancer. A composite video image  336  is shown on a display screen  338 , which composite video image  336  is produced by the control electronics  310  and is transmitted to the display screen  338  via electrical wires  340 . The composite video image  336  shows the locations, shapes, sizes, and the relative degrees of malignancy of any cancerous and/or pre-cancerous regions overlaid on a visual (white-light) image of the tissue sample  306 . The treatment light source  350  is shut off by the control electronics  310 .  
         [0066]    At this point, the user of the invention may interact with the control electronics  310  through the use of a user input device  342 , which user input device  342  may consist of one or more of the following: a keyboard, mouse, joystick, or any other common electronic input device. The user input device  342  is connected to the control electronics  310  via a set of electrical wires  344 . Through a combination of mathematical comparison of the various filtered images and input from the user, the control electronics  310  determine those regions of the tissue sample  306  that require treatment and in what proportion. If the control electronics  310  determine that the tissue sample  306  does not require any treatment at this point, then the control electronics  310  surrender control to the user, through the use of the user input device  342 , and further action of this embodiment of the invention  300  is ceased.  
         [0067]    The control electronics  310  next send signals via electrical wires  346  to the treatment beam shaping mechanism  348 , thereby ensuring that when the treatment light source  350  is turned on, the shape of the treatment light beam  252  will be properly controlled by spatially-selective reflection from the beam shaping mechanism  348 . For example, the treatment beam shaping mechanism  348  may consist of a Digital Micromirror Device (DMD), wherein each pixel on the mechanism consists of a tiny micro-mirror, which micro-mirror may be individually turned on or off, thereby allowing or prohibiting a small portion of the treatment light  352  from reflecting in a direction that allows it to be re-imaged with the optical system  358 . The pixels of such a device would be turned on and off in such a way that only the regions of the tissue sample  306  that were determined to require light treatment will receive light treatment, and they would receive treatment light  356  in proportion to the amount required. Because the treatment beam shaping mechanism  348  is intentionally positioned at a focal plane of the optical system  358 , it is a simple matter to turn on the pixels in the treatment beam shaping mechanism  348  that correspond to the pixels in the sensor array  326  that were found to contain images of cancerous and/or pre-cancerous tissue regions.  
         [0068]    The control electronics  310  next send signals via electrical wires  354  to the treatment light source  350 , thereby turning on the treatment light source  350  and causing treatment light  352  at a certain, predetermined power level and wavelength to be emitted in a direction toward the treatment beam shaping mechanism  348 . The power level and wavelength are determined such that the treatment light beam  356 , where it interacts with the tissue sample  306 , will cause photoactivation of the photosensitizing drug in the tissue sample  306 . The treatment beam shaping mechanism  348  causes the treatment light  352  to become shaped so as to act most effectively in the treatment of cancerous and/or pre-cancerous regions of the tissue sample  306 . The shaped treatment light beam  332  is first collimated with the imaging lens  358  and next reflects off the partial mirror  330  and is thus redirected toward the tissue sample  306 . The imaging lens  358  causes the treatment beam  332  to become focused, in reflection off the partial mirror  330  onto the tissue sample  306 . Because the treatment beam  332  was previously shaped with the treatment beam shaping mechanism  348 , the focused treatment beam  356  will illuminate only the regions of the tissue sample  306  that have been determined to require illumination with the treatment beam  356 . After a pre-determined amount, or dosage, of treatment light  352  has been shone from the treatment light source  350 , the control electronics  310  shut off the treatment light source  350 . At this point, the control electronics automatically begin the treatment phase of action once more.  
         [0069]    [0069]FIG. 7 shows a schematic illustration of a fourth preferred embodiment of the invention  400 . As shown in FIG. 7, all the components of this embodiment of the invention  400  are enclosed within and/or attached to a housing  402 . This fourth embodiment acts in such a manner that treatment and detection are simultaneous. This fourth embodiment also acts in such a manner that detection and treatment light are coaxial, in that the share a common optical axis through the optical system  418 .  
         [0070]    In this fourth embodiment, the multispectral imaging system  418  is substantially similar to the multispectral imaging system  218  described in the second embodiment, above. In the current embodiment, however, two elements have been added to the optical system  418 . First, a flat reflector  462  is introduced in a position that is substantially near the refracting prism  424 . The flat reflector  462  may comprise a full mirror, or a polarizing beamsplitter, or a dichroic reflector, or a partial mirror. The flat reflector  462  is shaped and positioned so that it overlaps with just one quadrant of the prism  424 . Second, a lens  458 , which lens  458  is substantially similar in design to the original final lens  421 , is positioned in a position that is substantially optically conjugate to the position of the original lens  421 . Finally, an aperture  460  is added substantially near the lens  458  in order to prevent stray light  461  from entering the optical system  418 . The addition of the reflector  462  and the lens  458  and the aperture  460  allows one of the four channels of the multispectral imaging system  418  to be at least partially redirected in a direction away from the imaging sensor plane  426 . This one at least partially redirected channel is used in the current embodiment to pass light  432  out through the optical system  418  and toward the target tissue sample  406 . With the optical system  418  thus modified from its original conception  218 , the current embodiment allows simultaneous detection through at least three of the optical channels and treatment and/or detection through the fourth optical channel.  
         [0071]    Note that if the flat reflector  462  is chosen to be a polarizing beamsplitter or a dichroic filter or a partial mirror, then the fourth optical channel will provide an image at the sensor plane  426 . In this case, for example, FIG. 5 shows a possible resulting image pattern  226  wherein four images  227  of the exact same region of the tissue sample  406  may be formed simultaneously on the sensor array  426 , arranged in a so-called “quad-format”. Note that although the four images  227  are shown having identical shapes, each has passed through a separate channel of the optical system  418 , and therefore each may have been filtered individually.  
         [0072]    Alternatively, for example, if the flat reflector  462  is chosen to be a full mirror, then FIG. 8 shows a possible resulting image  500  received by the sensor plane  426 , wherein three copies of the image  502  are produced simultaneously on the sensor plane  426 , and the light from one channel, having been redirected by the full mirror  462 , is absent, thus leaving one quadrant  504  of the final image  500  completely dark.  
         [0073]    Referring again to FIG. 7, note that the flat reflector  462  may be mounted in a moveable housing  464 , which housing  464  is designed so as not to optically obstruct any part of the optical path of the imaging system  418 . The moveable housing  464  may be easily moved to a position completely outside the optical system  418 . The moveable housing  464  may be easily moved either by the user or by a servo control motor  466 , which motor  466  is connected via electrical wires  468  to the control electronics  410 . When the moveable housing  464  containing the reflector  462  is moved to a position outside the optical system  418 , the optical system  418  acts in a manner substantially identical to the manner in which the previously described four-channel multispectral imaging system  218  acts.  
         [0074]    The following describes a method of operation of the fourth embodiment, shown in FIG. 7. The first step involves the user applying a photosensitizing drug (also called a porphyrin) to the patient. This photosensitizing drug may be applied intravenously or topically. Examples of photosensitizing drugs include Photofrin® and delta- or δ-amino levulinic acid (ALA). The user next allows the drug sufficient time to be absorbed into the cells of the tissue, before the treatment phase continues.  
         [0075]    Control electronics  410  are connected electrically to a light source  450  by electrical wires  454 . Signals from the control electronics  410  cause the light source  450  to emit light  452  at a certain, predetermined power level and wavelength range to be emitted in a direction toward the treatment beam shaping mechanism  448 . Light  452  from the illumination source  450  impinges upon a spatial light modulator  448  (such as a digital micromirror device, or DMD). As is well understood in the art of DMD systems, the effective reflectivity value of each pixel is controlled by flickering each individual micromirror on and off with a certain duty cycle.  
         [0076]    The power level and wavelength range of the emitted light  452  are determined such that the treatment light beam  456 , where it interacts with the tissue sample  406 , will cause photoactivation of the photosensitizing drug in the tissue sample  406  when the any given pixel in the DMD is set to its highest pixel reflectivity value. The DMD is initially set to act as a plane reflector, with all its pixels in the same effective reflectivity value. Thus at this stage, the level of the reflected light  432  is at a level below that which would cause photoactivation of the photosensitizing drug in the tissue sample  406 .  
         [0077]    The reflected light  432  passes through an aperture  460 , is next focused by a lens  458 , and reflects from a reflector  462 . The remaining elements  420 ,  422 ,  424  of the optical system  418  act to focus the light  456  through the window  414  in the side of the housing  402  and onto the target tissue sample  406 . Interaction of the light  456  with the target tissue sample  406  causes reflected and/or fluorescent emitted light  416  to be directed, to some degree, toward and through the window  414 . For example, the light  456  may be red, and fluorescent light  416  (at a slightly longer wavelength than the incident light  456 ) will be emitted from the tissue sample  406 . Upon passing through the window  414 , this reflected and/or fluorescent emitted light  416  is collected with an optical system  418 .  
         [0078]    As described previously, the optical system  418  acts to produce a plurality of differently filtered images of the tissue sample  406  on the sensor array  426  simultaneously. In the present example, a four-channel multispectral imaging system  418  produces three simultaneous images on the sensor plane  426 , with the fourth channel of the multispectral imaging system  418  being used to transmit light outwards.  
         [0079]    Each of the four filters in the filter plane  422  may act to transmit a specific band of wavelengths or a specific polarization of light. For example, three images of the exact same region of the tissue sample  406  may be formed simultaneously on the sensor array  426 , arranged in a so-called “quad-format”, as shown in FIG. 8, with one of the four image locations being totally devoid of light. Referring again to FIG. 7, the optical system  418  causes the incoming reflected and/or fluorescent emitted light  416  to become filtered and subsequently focused  428  into a plurality of simultaneous images on a sensor array  426 , wherein the light forming each of the simultaneous images has passed through a different filter in the filter plane  422 . One or more of these filters in the filter plane  422  may be transparent or clear. Also, one or more of these filters in the filter plane  422  may each allow only a certain polarization state of light to pass through. Also, one or more of these filters in the filter plane  422  may each allow only a single, narrow band of wavelengths of light to pass through. Also, one or more of these filters in the filter plane  422  may each allow a plurality of separate bands of wavelengths to pass through. Note that the entire filter plane  422  may be mounted on an easily-replaced fixture, such as a filter-wheel, allowing either the user or the control electronics  410  to exchange the set of filters in the filter plane  422  with a different set of filters, as may be required at various times in the action of the invention. In addition, the flat reflector  462  may be moved into or out of the optical system  418  as described previously.  
         [0080]    Image information from the sensor array  426  is transmitted to the control electronics  410  via control wires  434 . The control electronics  410  process the images thus obtained. The control electronics  410  use mathematical comparison of the various filtered images to compute the presence or absence of cancerous and/or pre-cancerous cells and the relative degree of dysplasia (pre-cancer) or cancer in the tissue sample  406 . A composite video image  436  is shown on a display screen  438 , which composite video image  336  is produced by the control electronics  410  and is transmitted to the display screen  438  via electrical wires  440 . The composite video image  336  shows the locations, shapes, sizes, and the relative degrees of malignancy of any cancerous and/or pre-cancerous regions overlaid on a visual image of the tissue sample  406 .  
         [0081]    The control electronics  410  next send signals via electrical wires  446  to the treatment beam shaping mechanism  448 , thereby ensuring that the shape of the treatment light beam  452  will be properly controlled by spatially-selective reflection from the beam shaping mechanism  448 . For example, the treatment beam shaping mechanism  448  may consist of a miniature Digital Micromirror Device (DMD) wherein each pixel on the mechanism consists of a tiny micro-mirror, which micromirror may be individually turned on or off, thereby allowing or prohibiting a small portion of the treatment light  452  from reflecting in a direction that allows it to be re-imaged with the optical system  418 . The pixels of such a device would be turned on and off in such a way that only the regions of the tissue sample  406  that were determined to require light treatment will receive light treatment, and they would receive treatment light  456  in proportion to the amount required. Because the treatment beam shaping mechanism  448  is intentionally positioned at a focal plane of the optical system  418 , it is a simple matter to turn on the pixels in the treatment beam shaping mechanism  448  that correspond to the pixels in the sensor array  426  that were found to contain images of cancerous and/or pre-cancerous tissue regions.  
         [0082]    The treatment beam shaping mechanism  448  causes the treatment light  452  to become shaped so as to act most effectively in the treatment of cancerous and/or pre-cancerous regions of the tissue sample  406 . The shaped treatment light beam  432  is first collimated with the lens  458  and next reflects off the flat reflector  462  and is thus redirected through the remainder of the optical system  418  and then on toward the tissue sample  406 . Note that the aperture  460  acts to prevent stray light  461  from entering the imaging system  418 . The imaging lens  458  co-acts with the rest of the imaging system  418  to cause the treatment beam  432  to become focused, in reflection off the flat reflector  462  onto the tissue sample  406 . Because the treatment beam  432  is shaped with the treatment beam shaping mechanism  448 , the focused treatment beam  456  will illuminate with high enough intensity to activate the photoactivated drug only the regions of the tissue sample  406  that have been determined to require treatment. Furthermore, the intensity of the beam at each location on the target tissue sample  406  is also controlled with the treatment beam shaping mechanism  448 . While the target tissue sample  406  is being treated with the beam-shaped treatment light  456 , the fluorescent and or reflected light  416  from the target tissue sample  406  is simultaneously focused onto the sensor plane  426 . The image produced at the sensor plane is used to control the shape of the treatment beam  432  in real-time. Thus, as the photoactivated drug is being activated, the amount of fluorescence and/or reflectance it produces will reduce over time, and the amount of treatment light directed toward it will correspondingly reduce over time. After a pre-determined amount, or dosage, of treatment light  452  has been shone from the treatment light source  450 , the control electronics  410  shut off the treatment light source  450 .  
         [0083]    It should be apparent that the illumination source used in the detection of the cancerous or pre-cancerous cells can be any source that emits in the desired wavelength range. For example, a white light source could be used, a gas discharge lamp could be used as well as a variety of other lamps. It should be noted that the present invention is not limited to these illumination sources. It should also be noted that, in some embodiments, such as, but not limited to, the embodiment shown in FIG. 7, the treatment light source ( 450  in FIG. 7) is also the detection (illumination) light source.  
         [0084]    While several embodiments of methods of collecting the flourescence and reflected signal in several spectral ranges were disclosed (filter wheels and the method of Ser. No. 60/303,243) other methods, such as those of U.S. Pat. No. 5,115,137, U.S. Pat. No. 4,786,813 and U.S. Pat. No. 6,208,749 could be used or adapted to be used.  
         [0085]    Although the preferred embodiment of the sensor array  82  or  226  or  326  or  426  is a CCD detector, it should be apparent that a CMOS detector or any optical radiation detector with the appropriate wavelength response could be used.  
         [0086]    Although mathematical comparison of the various filtered images is used to compute the presence or absence of cancerous and/or pre-cancerous cells in the tissue sample  56  or  206  or  306  or  406 , it should be apparent that other techniques could be used for detection. For example, the method of U.S. Pat. No. 6,135,935 could be used or the method of U.S. Pat. No. 5,623,932 or U.S. Pat. No. 6,256,530 could be adapted and used.  
         [0087]    The treatment light source  38 , or  102  or  250  or  350  or  450  could be, but is not limited to, a laser emitting light of the appropriate wavelength or a light source such as an LED emitting light of the appropriate wavelength.  
         [0088]    The beam shaping mechanism  104  or  248  or  348  or  448  may be, but is not limited to, a spatial light modulator such as a Liquid Crystal array or a Digital Light Processor (such as a Grating Light Valve), a Micro Mirror Array, an Acousto-optic modulator (AOM), or a galvo mirror or an array of galvo mirrors. The beam shaping mechanism  104  or  248  or  348  or  448  may be, in one embodiment, combined with the treatment optical radiation source  102 ,  250 ,  350 ,  450  as, for example, in utilizing a controllable array of sources.  
         [0089]    While the embodiments of the present invention has been described above in reference to a treatment beam, it should be noted that “beam” as used hereinabove also refers to more than one beam or a group of “beamlets” as, for example, but not limited to, the resulting radiation formed when a beam is shaped by a Micro Mirror Array or an array of galvo mirrors or produced by a controllable array of sources.  
         [0090]    It should also be noted that although the embodiment of the invention described herein below refers to tissue sample, the invention can be practiced in other embodiments where a sample is treated and the treatment detected, such as, but not limited to, the curing of materials or the annealing of materials.  
         [0091]    A detailed description of multiple imaging optical system ( 218 ,  318 ,  418 ) is provided in appendix A of U.S. Provisional Application 60/356,302 and also in U.S. patent application Ser. No. 10/187,912 (filed on Jul. 2, 2002), hereby incorporated by reference. The multiple imaging optical system described in U.S. Provisional Application 60/363,997 can also be used as another embodiment of the multiple imaging optical system of this invention.  
         [0092]    Although the invention has been described with respect to various embodiments, it should be realized this invention is also capable of a wide variety,of further and other embodiments.