Abstract:
Apparatus and methods for detecting and removing foreign matter on an in vivo blood content sensor window utilizing time and wavelength techniques to provide more beneficial information to an operator to facilitate for more accurate blood content readings.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to the utilization of light scattering and absorption techniques to detect possible obstructions or foreign matter on blood content sensor lenses. More specifically, the invention relates to an apparatus and method for utilizing light to detect foreign matter on the window sensor of a blood content sensor system. 
       BACKGROUND OF THE INVENTION 
       [0002]    Scientists have discovered that a detectible increase in the blood content of superficial mucous membrane occurs proximate cancerous and precancerous lesions in the colon relative to the blood content of healthy tissue as described in, for example, R K Wali, H K Roy, Y L Kim, Y Liu, J L Koetsier, D P Kunte, M J Goldberg, V Turzhitsky and V Backman, Increased Microvascular Blood Content is an Early Event in Colon Carcinogenesis, Gut Vol. 54, pp 654-660 (2005), which is incorporated by reference herein. This phenomenon is referred to as early increase in blood supply (EIBS). 
         [0003]    Relying on this phenomenon, it is known that it is possible to predict an area of potential abnormality based on early increase in blood supply (EIBS) in the area of abnormality. Further, it has been discovered, that by using a probe applying collimated light to an area of interest, and detecting the amount of absorbed and reflected light it is possible to provide blood content or blood flow information to a clinician to guide an endoscope to detect a possible abnormality in vivo without an invasive procedure. Such techniques have been described for example in U.S. patent application Ser. No. 11/937,133 filed on Nov. 8, 2007, entitled “Blood Content Detecting Capsule”, assigned to the assignee of the present invention, which is incorporated by reference herein. 
         [0004]    Typically, blood content or blood flow detection relies on measuring the amount of light reflected from the tissue mucosa back into the blood content sensor. Because systems rely on measuring the amount of reflected light, the accuracy of the measurements are greatly impacted if the blood detection apparatuses window is obstructed by foreign liquid or solid matter on the lens. Further, the accuracies of any measurement or foreign matter detection techniques are impacted if there is extraneous light detected by the sensors as a result of other observation devices such as a traditional CCD camera light. 
         [0005]    Various techniques exist for removing foreign liquid or solid matter from endoscope lenses while in vivo, e.g., nozzle sprayers of water onto the endoscope or blood content sensor windows, however, techniques still lack a method to detect if the observation window is actually clean. In an observation only system, i.e., one without a blood content sensor, an operator may determine if there is foreign matter on the observation window by subjectively viewing of the image. However, in blood content sensor systems, there is no viable image for an operator to view, therefore an operator cannot make a determination about the presence of foreign matter on the detector window. 
         [0006]    Further, when it is desirous to determine the presence of foreign matter on the blood content sensor window, the endoscope tip or blood content sensor window is removed from the surface of the tissue. As a result, illumination light from the scope observation source, e.g., endoscope camera, may be scattered by the surface of the living tissue and reach the receiving fibers of the blood content sensor. In that case, a false reading of the level of foreign matter present will occur because light from the observation source is attributed to the blood content sensor itself, thereby falsely determining the presence or absence of foreign matter. 
         [0007]    Accordingly, in order to improve the accuracy of blood content measurements there needs to exist a technique for objectively determining if the measurement lens is obstructed by foreign matter. 
       SUMMARY OF THE INVENTION 
       [0008]    Systems and methods that detect liquid and solid foreign matter on the blood content sensor of the present invention advantageously facilitate higher data accuracy from such sensors. Further aspects of the invention minimize the amount of extraneous light that enters the blood content sensor during periods of foreign matter detection. In one exemplary embodiment using blood content sensors with a scope, such as an endoscope or colonoscope, independent light sources are alternatively activated to sequentially produce light for (1) blood content detection and foreign matter detection and (2) observation through the scope by a clinician. In particular, light for scope observation is emitted at time intervals between the time intervals that separate light is emitted for use in blood content detection or foreign matter detection. In this manner, potential adverse effects are reduced for any extraneous light generated for scope observation will be reflected into the blood content detection window during blood content or foreign matter detection. 
         [0009]    In accordance with another embodiment of the invention, light of different wavelengths or ranges is used for the respective functions of scope observation and blood content detection (including foreign matter detection). The detection of foreign matter on the blood content sensor, and accordingly the detection of blood content abnormalities are improved as a result of the different light wavelengths used for scope observation and that used for blood content detection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  illustrates a block diagram of an exemplary system in accordance with one aspect of the invention utilizing blood content sensors; 
           [0011]      FIG. 2  illustrates a cross sectional view of an exemplary embodiment of an endoscope tip containing a blood content sensor in contact with tissue mucosa; 
           [0012]      FIG. 3  illustrates the exemplary embodiment of the endoscope tip in  FIG. 2  not in contact with the tissue mucosa; 
           [0013]      FIG. 4  illustrates an exemplary diagram of an endoscope tip usable with the present invention; 
           [0014]      FIG. 5  illustrates an exemplary diagram of light intensity vs. time of the observation and detection lights in accordance with an aspect of the invention; 
           [0015]      FIG. 6  illustrates an exemplary diagram of light intensity vs. time of the observation and detection lights in accordance with another aspect of the invention; 
           [0016]      FIG. 7  illustrates an exemplary diagram of light intensity vs. wavelength of the observation and detection lights in accordance with further aspect of the invention; 
           [0017]      FIG. 8  illustrates an exemplary diagram of light intensity vs. wavelength of the observation and detection lights in accordance with yet another aspect of the invention; 
           [0018]      FIG. 9  illustrates an exemplary diagram of light intensity vs. wavelength of the observation and detection lights in accordance with another aspect of the invention; 
           [0019]      FIG. 10  illustrates an exemplary diagram of light intensity vs. wavelength of the observation and detection lights in accordance with a further aspect of the invention; 
           [0020]      FIG. 11  depicts an exemplary capsule endoscope system in incorporating aspects of the present invention; 
           [0021]      FIG. 12  depicts an exemplary embodiment of a capsule endoscope in accordance with the present invention in contact with underlying tissue; 
           [0022]      FIG. 13  depicts the exemplary embodiment of the capsule endoscope of  FIG. 12  a distance from underlying tissue; 
           [0023]      FIG. 14  depicts a representative image displayed from a capsule endoscope in accordance with the present invention in contact with underlying tissue; 
           [0024]      FIG. 15  depicts a representative image displayed from a capsule endoscope when the blood content sensor window is a distance from underlying tissue; 
           [0025]      FIG. 16  illustrates an exemplary diagram of an endoscope tip usable with the present invention; 
           [0026]      FIG. 17  illustrates a side view of the endoscope tip of  FIG. 18 ; and 
           [0027]      FIG. 18  illustrates an exemplary diagram of another endoscope tip configuration usable with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The present invention relates generally to improvements in detection of deleterious foreign liquid or solid matter that may deposit on blood content sensors. Such improvements are advantageously usable with blood content sensors implemented with, for example, traditional and capsule-type endoscope configurations. 
         [0029]    Particular blood content sensors for detecting blood content or blood flow such as for example, those described in the above referenced previously filed U.S. patent application Ser. No. 11/937,133, typically operate when in direct contact with living tissue, such as mucosa tissue. As used herein, blood content sensors refer to sensors refer to sensors that detect blood content or blood flow. One principle of the invention is based on foreign matter detection with the blood content sensor when the blood content sensor is not contacted with living tissue. In such instance, an illuminator for blood content detection and the blood content sensor share a common outer window. When the window is at a distance from tissue and in absence of foreign matter on the window, all or most of the emitted light will be dispersed and little or no light will be reflected back into the sensor. 
         [0030]    If, however, foreign matter is present on the window, then an easily measurable quantity of emitted light will be reflected back through the common window by the foreign matter. Accordingly, if, for example, the intensity of reflected light is equivalent to or higher than a predetermined threshold when such window is not in contact with tissue, then it can be presumed that foreign matter is present on the window. It is understood by those skilled in the art that many configurations are conceivable that exploit this elementary concept in detecting the presence of foreign matter on a sensor. 
         [0031]    Referring to the drawings, like numbers indicate like parts throughout the views as used in the description herein, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes both “in”, and “on” unless the context clearly dictates otherwise. Also, as used in the description herein, the meanings of “and” and “or” include both the conjunctive and disjunctive and may be used interchangeably unless the context clearly dictates otherwise. 
         [0032]      FIG. 1  depicts a block diagram of an exemplary endoscope system  100  containing a blood content detection sensor  6 . System  100  further contains video monitor  1 , observation light  2 , endoscope image converter  3 , blood content sensor light  4 , blood content control unit  5  and endoscope  7 . 
         [0033]    A conventional endoscope configuration is usable for endoscope  7  in accordance with the invention. Consequently, in typical observation mode, endoscope  7  is inserted proximate living tissue such as, for example, the colon or other tissue along the gastrointestinal track. Observation light source  2  generates light that is transmitted via endoscope  7  and reaches the surface of the target living tissue. Light is reflected off the tissue under investigation and reenters endoscope  7  through a series of lenses. The reflected image is processed by endoscope image converter  3  which may contain a CCD or other image processing device creating digital signals representing an image of the target tissue. The signals from image converter  3  are transmitted to monitor  1  where they are converted into a video image displayed to an operator or clinician. 
         [0034]    However, unlike conventional endoscopes that system  100  is also operable in a blood content measurement mode. In blood content measurement mode, blood content light source  4  generates light to be conveyed to endoscope  7 . Endoscope  7 , while contacting the tissue mucosa under investigation, illuminates the tissue with the light from blood content sensor light source  4  and then receives back at the blood content sensor  6 , scattered or reflected, i.e., interacted light, from the underlying tissue. The interacted light is conveyed by the sensor  6  to the blood content control unit  5 , such as by an optical or electrical signal. 
         [0035]    The blood content control unit  5  receives this data and provides it to a data preprocessor, that executes, for example, a data correction algorithm, such as white correction represented in the following equation (1). 
         [0000]    
       
         
           
             
               
                 
                   
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         [0036]    Where the symbols π and ⊥ used in the numerator and denominator of equation (1) represent the spectrum of horizontally polarized light and the spectrum of vertically polarized light, respectively. In equation (1), λ represents wavelength, ΔI(λ) indicates the measured difference polarization spectrum, ΔIw(λ) is the spectrum measured using a standard white plate and is calculated by summing the white horizontal polarization spectrum Iwπ(π) and the white perpendicular polarization spectrum Iw ⊥(λ), as shown in the denominator of equation (1). In the numerator of equation (1), the difference between the horizontal polarization spectrum Iπ(λ) and the perpendicular polarization spectrum I ⊥(λ) is calculated and a signal indicative of ΔI(λ). 
         [0037]    The blood content control unit  5  calculates the blood content by using equation (2) below, which is shown in, for example, M. P. Siegel et al. “Assessment of blood supply in superficial tissue by polarization-gated elastic light-scattering spectroscopy,” Applied Optics, Vol. 45, Issue 2, pp. 335-342 (2006). 
         [0000]      Δ I (λ)=Δ I   scattering (λ)exp[−α A   PG (λ)]  (2) 
         [0038]    Blood content control unit  5 , using a model equation, such as equation (2), provides a corresponding blood content value to monitor  1  or other display devices. Alternatively, the blood content control unit  5  may also provide the blood content value to a data validator as a check on the integrity of the collected data. Blood content control unit  5  may also provide the results from the sensor  6  to a comparator unit (not shown) to determine the validity of a measurement and to improve the accuracy of detection based on the measurement window. 
         [0039]    In foreign matter detection mode operation in accordance with one aspect of the invention, the endoscope  7  is positioned with the sensor  6  a distance from the tissue under investigation. In such operation mode, light is generated by blood content sensor light  4  and reflected light is detected, by sensor  6  and correspondingly measured and processed by blood content unit  5 . If no foreign matter is present on the external sensor window then all or most of the light will be emitted through the window and will be dispersed. Very little light will be reflected and subsequently detected by sensor  6 . If however, foreign matter has deposited on the detection window, then a detectable amount of light will be reflected back by the foreign matter and into the sensor  6 . Accordingly, if the intensity of the reflected light that is detected is equivalent to or higher that a predetermined threshold then it is presumed that foreign matter has deposited on the window and that the reflected light that is detected is a result of reflection off of such foreign matter. 
         [0040]    More detailed operation of such exemplary system will now be described with respects to  FIGS. 2 and 3 . Referring to  FIG. 2 , the tip of endoscope system  200  comprising a blood content detection section  220  and an optical observation section  230 . The blood content or section  220  contains receiving fibers  201  and  203 , illumination fiber  202 , linear polarizers  204  and  205 , lens  207 , blood content detection window  208 . Observation section  230  contains light transmission fiber  212 , illumination window  213 , observation window  211 , observation lens  210 , imaging unit  214 , such as a CCD or other imaging device, and transmission line  209 . The receiving fibers  201  and  203  may be coupled to the blood content sensor control unit  5  of  FIG. 1 . 
         [0041]      FIG. 2  further depicts the system  200  in a blood content detection position, i.e., in contact with tissue  206 . During operation, light from the blood content sensor source is conveyed on illumination fiber  202  through polarizer  204 . The emitted polarized or collimated light passes through lens  207  and enters blood content detection window  208 . The emitted light strikes tissue  206  and is scattered and reflected based on the interaction with the tissue  206 . The reflected light passes back through blood content window  208  and through lens  207 . Light passing through polarizer  204  is aligned with the transmitted light since it passes through the same polarizer  204 . In the depicted embodiment, polarizer  205  is orthogonal to polarizer  204  and any light passing through it is accordingly conveyed to receiving fiber  203  represents collimated light with a different angle of polarization relative to the transmitted light. 
         [0042]    Because the tip of the endoscope  200  is in contact with the tissue mucosa  206  during blood content detection measurement, the image received via observation lens  210  and conveyed to imaging unit  214  is obstructed and may be washed out. Because all the light emitted by  213  is absorbed by tissue  206 , there is no area of tissue illuminated for the operator to observe. 
         [0043]    Prior to performing any blood content detection, the operator will have to make a determination regarding whether the blood content sensor window  208  is sufficiently clean of obstructions or foreign matter to determine whether a blood content measurement should be performed or whether the lens and window should be rinsed to remove the foreign matter by any one of known techniques, including for example use of spray nozzle on the endoscope tip or a water flow outlet in the endoscope tip. These determinations may be made when the blood content sensor  220  is not in contact with the underlying tissue  206 . 
         [0044]    In order to determine if the blood content sensor  220  in the tip of the instrument  200  is in contact with the tissue, it is possible to use, for example, either a mechanical or electromagnetic contact sensor such as sensors  222 , or by observation by an operator through lens  210  and  211 . When the blood content sensor  220  is not in contact with tissue  206 , it is possible to perform a foreign matter measurement. Suitable contact sensors like sensor  222  to indicate contact with the tissue mucosa may include, for example, specifically designed endoscopes, pressure sensors, balloons, or the like. Such contact sensors are likewise suitable for blood content sensors employed in instruments other than endoscopes or employed alone. 
         [0045]    In  FIG. 3 , the tip of system  200  is depicted at a distance from and not in contact with the tissue mucosa  206 . Accordingly, in this position, illumination window  213  and blood content detection window  208  are not in contact with tissue  206  and not in a position to perform a blood content measurement. During operation in this position, observation light is transmitted on light transmission fiber  212  to illumination window  213 . Light emitted from window  213  strikes tissue  206  and illuminates an area to be observed. The reflected light enters observation window  211  and is focused through lens  210  onto imaging unit  214 . The image signals generated from imaging unit  214  are conveyed on transmission line  209  to a display, such as monitor  1  of  FIG. 1  for observation by a clinician. 
         [0046]    Also, in the tip position shown in  FIG. 3 , the light exiting illumination window  213  may be reflected back through blood content detection window  208  and be received on receiving fibers  201  and  203  and then processed by the blood content sensor control unit  5  of  FIG. 1 . If this occurs during a period of time when the blood content sensor is determining the presence or absence of foreign matter on window  208 , a false reading may occur regarding the existence of foreign matter on the blood content detection window  208 . Such a result may yield an incorrect reading. To eliminate this undesirable occurrence, the timing of the activation of the observation light transmitted on illumination transmission fiber  212  and light transmitted on blood content illumination fiber  202  are such that light is not simultaneously emitted by the fibers  212  and  202 . 
         [0047]      FIG. 5  illustrates an exemplary timing sequence for use with an embodiment of the present invention. As seen in timeline  501 , illumination for scope observation by a clinician is generated by a first light source and emitted from observation window  213  in the sequence order oft for example, red light, green light, and then blue light during the intervals R, G and B, respectively. At such time intervals as shown in  FIG. 3 , the light is reflected off the tissue  206  and enters lens  210  and is focused on imaging unit  214 . Imaging unit  214  may, for example, be a monochrome CCD or color CCD or other image capturing device. The corresponding digital or analog image signals produced by the imaging unit  214  are then transmitted on transmission line  209  for display to the operator. 
         [0048]    At time intervals, during the off or shielded periods  502  in  FIG. 5  between the red, green, and blue illumination sequence intervals R, G and B, used for observation, blood content detection light  503  is transmitted on fiber  202  for emission out of blood content detection window  208  to detect foreign matter. Because the blood content sensor  220  in  FIG. 3  is not in contact with the underlying tissue, only a minimum amount of transmitted light should be reflected into the blood content detection window  208  if no foreign matter is present on said window  208 . Further, because the blood content sensor light is transmitted during the periods  502  in  FIG. 5  when the observation light is off or shielded, the possibility of extraneous light used for observation entering the blood content window  208  and interfering with this reading is eliminated. 
         [0049]    Accordingly, during intervals  502 , if the intensity of the light used for blood content detection is measured and found to be equivalent to or higher than a threshold level such as, for example, approximately 10% of the intensity typically detected for interacted light when the blood content sensor  220  is in contact with the tissue  206  then it is presumed that the blood content sensor light is being reflected by foreign matter disposed on the window  208 . Once it is known that foreign matter is present, an operator may take the appropriate steps to remove such matter. 
         [0050]      FIG. 6  illustrates an alternative timing sequence useable in accordance with another embodiment of the present invention. Rather than sequentially transmitting red, green, and blue light for scope observation as shown in  FIG. 5 , broad band light  601  in, for example, the 400 to 700 nm wavelength range may be alternatively transmitted during intervals  604  and then shielded during intervals  602 . During the shielding intervals  602 , the light used for blood content detection  603  is generated to detect foreign matter or to perform blood content measurements. In accordance with this embodiment, the wavelength of light used for illumination  601  and measurement  603 , including the detection of foreign matter from the blood content sensor is not particularly limited. For example, light in the 500 to 600 nm wavelength range may also be used as described in M. P. Siegel, et al., Applied Optics Vol. 45, No. 2 pp. 335-342, 2006, which is incorporated by reference herein. 
         [0051]    In another embodiment of the present invention, generated light used for scope observation by a clinician is at different wavelengths than light used for blood content detection and foreign matter detection. As a consequence, in this embodiment light generated for scope observation and for the blood content sensors as separated in frequency (or wave-length) as opposed to time as shown in  FIGS. 5 and 6 . In this exemplary wavelength-based embodiment, the endoscope  7  of  FIG. 1  emits broad-band illumination light in, for example, the wavelength range of the 400 to 700 nm in a continuous manner rather than as sequentially pulses. Because of the use of broad-band light in the 400 to 700 nm wavelength range, a color CCD may be used for acquiring images for scope observation. Such an arrangement is illustrated in  FIG. 7 . 
         [0052]    As seen in  FIG. 7 , light  701  in the 400 to 700 nm range is used for scope observation. Light  702 , also in the 400 to 700 nm range is further used for blood content detection and light  703 , a different range such as, for example, in the 700 to 1000 nm range would only be used for foreign matter detection. This embodiment will now be described in conjunction with  FIGS. 2 and 3 . Light  701  may be continuously emitted or pulsed from observation window  213 . During the periods when the probe is not in contact with tissue  206 , reflected light will enter observation window  211  and be conveyed to color imaging unit  214 . The image will then be conveyed on transmission line  209  for observation on an external monitor. Simultaneously, the blood content sensor will be emitting light  702  and  703  from transmission fiber  202 . Light  702  and  703  will strike tissue  206  and, if there is no foreign matter present, only minimal amounts of light will be reflected back into receiving fibers  204  and  205 . 
         [0053]    Because light  703  is of a different wavelength range than light  701  or  702 , any extraneous light  701  or  702  that might be received back by receiving fibers  204  and  205  will not impact the foreign matter detection measurement. If detected light intensity in the 700 to 1000 nm range exceeds a threshold value, such as, for example, approximately 10% of the intensity typically detected for interacted light when the blood content sensor  220  is in contact with the tissue  206 , during the time when the probe is not in contact with tissue  206 , then the operator clinician may presume that foreign matter is present, and can take the necessary cleaning steps to remove it. 
         [0054]    During the period when the probe is in contact with tissue  206 , any light generated for scope observation,  201  in the 400 to 700 nm wavelength and conveyed though observation window  213  will not enter blood content sensor window  208  and receiving fibers  201  and  203  because of the contact with the underlying tissue. In this manner no false blood content readings will occur. In contrast, when the probe is not in contact with tissue  206 , the extra light transmitted from transmission fiber  202  will aid in illumination for general observation. 
         [0055]    In an alternative exemplary embodiment depicted by  FIG. 8 , light  801 - 803  for scope observation is sequentially emitted in the order of red light  801 , green light  802  and blue light  803  and covers light in the 400 to 700 nm range. Light used for blood content detection  804  may also be in the 400 to 700 nm range while light  805  used for foreign matter detection is emitted in the 700 to 1000 nm range. Such an exemplary configuration may be applied in a frame-sequential system that sequentially emits the red light  801 , green light  802 , and blue light  803  rather than a continuous system that utilizes continuous broad-band light. 
         [0056]    Because of the separation of light by wavelength, between the light used for foreign matter detection  805  and the light used for scope observation  801  to  803 , there is no interference when the blood content sensor is performing a foreign matter detection measurement. Accordingly, if the light received by fibers  201  and  203  in the 700 to 1000 nm range exceeds a threshold, then the operator may presume that foreign matter is disposed on the window of the blood content sensor. 
         [0057]      FIG. 9  depicts an alternative embodiment light configuration of the present invention. In this embodiment, light used for blood content measurement and scope observation is not particularly limited. Advantageously, light for scope observation may be continuous covering the wavelength spectrum of, for example, 400 to 700 nm or may be sequentially transmitted as red light  901 , green light  902  and blue light  903 . Light for blood content detection  905  may be in the 500 to 600 nm wavelength range, and light for foreign matter detection  904  and  906  may be in the 350 to 400 nm or 700 to 1000 nm wavelength range respectively. 
         [0058]    In another embodiment described with reference to  FIG. 10 , foreign matter detection is advantageously accomplished by utilizing a total spectrum for observation broader then that spectrum used for calculating blood content detection alone. Such an embodiment yields a higher isolation of illumination light for scope observation, thereby improving the accuracy of the foreign matter detection. When detecting foreign matter, generally the larger the range of wavelengths covered by the blood content sensor, the higher the signal-to-noise ratio will be, yielding an improvement in foreign matter detection. Because light emitted from observation window  208  is scattered near the surface of tissue  206 , the measurable energy of light received at receiving fibers  201  and  203  is likely to be low. 
         [0059]    Accordingly, it is advantageous to provide a system that has sufficient sensitivity for detecting very weak signals reflected by foreign matter on the blood content measurement window  208 . By detecting foreign matter with a broad wavelength of light, overall sensitivity is improved. As seen in  FIG. 10 , scope observation light  101  is sequentially emitted in the 400 to 700 nm wavelength range to form a continuous signal. Light  105  is utilized for blood content detection and falls within the range of 350 to 1000 nm wavelength, and preferably, in the 500 to 600 nm range. Light wavelength range  104  and  106  surround light wavelength range  105  and encompass a range broader than the light range  101 , for example, making up the range from 350 to 1000 nm wavelength. In this manner foreign matter detection requires that light  104  and  106  be detected at a sufficient level to indicate foreign matter on window  208 . Because of the broader spectrum of light to detect. The corresponding light energy received by the blood content sensor may advantageously be higher than for a narrower band of light. 
         [0060]    In addition to traditional endoscope techniques, the foreign matter detection techniques of the present invention are equally applicable to capsule type endoscopes as well.  FIG. 11  shows an exemplary embodiment of a capsule type endoscope system in use within a patient. 
         [0061]    System  110  includes a capsule endoscope  111  and a host processing unit  112 . Capsule endoscope  111  is inserted into an organ such as a colon  1131  or ingested orally by a patient. Capsule endoscope  111  wirelessly transmits, represented by reference  114 , to host processing unit  112 . The wireless transmission can be any known transmission method including known wireless methods such as induction or radiofrequency (RF) methods. Based on the data received at host processing unit  112 , an operator can determine if the capsule and its respective blood content window are in contact with the tissue mucosa of colon  113 . During the periods when the operator determines that the blood content window of the capsule endoscope  111  is not in contact with the underlying tissue mucosa, foreign matter measurements can be performed to determine if there is any foreign matter on the surface of the blood content window. 
         [0062]      FIG. 12  depicts an exemplary capsule endoscope in contact with the tissue mucosa of the organ under investigation.  FIG. 13  depicts the same endoscope capsule when the blood content sensor window  124  is not in contact with the tissue mucosa of the organ under investigation. 
         [0063]    Capsule endoscope  120  of  FIGS. 12 and 13  is comprised of four main components. Within capsule shell  134 , is located (1) a power supply  130  for generating DC power to the other components of the capsule; (2) data transmitter  131  for transmitting the image data, blood content data and foreign matter data to the host processing unit; (3) a blood content sensor portion  190 ; and (4) a image observation portion  195 . The blood content sensor portion  190  may be comprised of for example, light source  121 , typically a LED or other suitable light source, a linear polarizer  122 , lens  123 , blood content window  124 , linear polarizer  126 , linear polarizer  127 , transmissive grating  128  and linear sensor  129 . The image observation portion  195  may include LEDs  132 , and image processing unit  133 , an image sensor such as a solid state sensor, e.g., CCD or other commonly used image capturing device. 
         [0064]    Operation will now be described with respect to  FIGS. 11 and 12 .  FIG. 12  depicts an exemplary capsule endoscope of the present invention when the blood content sensor window  124  is in contact with the tissue  125 . Light source  121  receives power from power source  130  and generates light for blood content detection. The generated light (indicated by arrows A and B) passes through linear polarizer  122 , lens  123 , and blood content detection window  124  before striking tissue  125 . The light striking living tissue  125  is scattered or reflected from and passes back through blood content sensor window  124 , lens  123 , and linear polarizers  126  and  127 . Linear polarizers  126  and  127  are orthogonally aligned such that the light passing through linear polarizer  126  is parallel to the transmitted light and light passing through linear polarizer  127  is perpendicular to the transmitted light. The light is then spectroscopicly analyzed by transmissive grating  128  and linear sensor  129 . Corresponding produced Data indicative of tissue blood content is then conveyed to data transmission unit  131  for transmission to the host unit  112 . 
         [0065]    The LEDs  132  and other components of the observation unit  190  are also powered by power supply  130  and emit light (indicated by the arrows C and D) through capsule shell  134 . The emitted light illuminates the tissue  125  and an image is captured on image sensor  133 . Image data is conveyed to data transmission unit  131  for transmission to the on host unit  112  of  FIG. 11 . Because blood content sensor window is in contact with living tissue  125 , the extraneous light from LEDs  132  does not enter the blood content detection window  124  and accordingly, does not cause false or inaccurate readings. 
         [0066]    In  FIG. 13 , the blood content sensor window  124  is shown not in contact with the tissue  125 . Accordingly, light generated by LED  132  used for scope observation may scatter and reflect back into the blood content sensor through window  124 , thereby affecting both blood content readings and foreign matter detection. 
         [0067]    To resolve this, LEDs  132  and  121  are alternatively energized so as to not emit light simultaneously and may be characterized by the illumination timing depicted in  FIG. 6 . As seen in the exemplary plot of  FIG. 6  broad-band light  601  in the 400 to 700 nm range is pulsed on and off. Images obtained during the on periods are transmitted back to host unit  112  for observation. During the shielding or off periods  602 , LED  121  generates a light pulse  603  that is used for blood content detection and foreign matter detection. By alternating, the illumination timing for observation with the illumination timing for blood content detection the interfering light issue is eliminated. By observing the image produced on the host unit  112 , an operator can determine if the capsule endoscope  120  is correctly aligned such that blood content window  124  is in contact with tissue  125 . 
         [0068]      FIGS. 14 and 15  indicate exemplary images received on the host processing unit  112  when the capsule is aligned in such a way that blood content sensor window  124  is either in contact with or away from tissue  125  respectively. As seen in  FIG. 14 , the center of the screen  151  displays the far field of the image so that a clinician can determine that the living tissue is away from the domed surface of capsule shell  134 . As can be confirmed by the image, the clinician can see by observation that the tissue is in contact with the capsule shell  134  and that the capsule is properly aligned for performing blood content measurements. Contrastingly, as depicted in  FIG. 15 , when capsule  120  is not aligned properly and the blood content sensor window  124  is not in contact with tissue  125 , the clinician will observe that the bottom of the image  161  displayed on the screen of host processing unit  112  only displays the far field, i.e., the capsule shell  134  is separated from the tissue  125 , thereby indicating to the clinician that the blood content sensor window  124  may be apart from and not in contact with the tissue  125 . 
         [0069]    If the blood content sensor window  124  is away from tissue  125 , and the intensity of the blood content observation light  121  is equivalent to of greater than a set threshold of, for example, approximately 10% of the intensity typically detected for interacted light when the blood content sensor  220  is in contact with the tissue  206 , it can be presumed that foreign matter is present on the window  124 . 
         [0070]    In accordance with another capsule embodiment of the invention, different light wavelength ranges are used for observation and for blood content detection in a similar manner to that described with respect to  FIG. 7 . 
         [0071]      FIG. 4  depicts an exemplary embodiment of an endoscope tip for use with the present invention. Endoscope tip  400  contains a front water-supply port  401 , illumination window  402 , scope observation window  403 , blood content sensor window  404 , spray nozzle  405 , illumination window  406  and utility channel  407 . Scope observation window  403  and blood content sensor window  404  are linearly aligned with spray nozzle  405 . When foreign matter is detected on blood content sensor window  404  by any of the methods previously described, the operator using one of any known techniques can spray water from spray nozzle  405  rinsing away foreign matter from both scope observation window  403  and blood content sensor window  404  utilizing the same spray nozzle for both, thereby minimizing the number of spray ports necessary on the endoscope tip. Further, employing this advantageous embodiment, during the rinsing of foreign matter or directly after, a foreign matter detection measurement may be performed by any of the embodiments previously disclosed to alert the operator that the blood content window is sufficiently clean and free from foreign matter to continue with blood content measurements. 
         [0072]    Another advantageous embodiment of an endoscope tip designed to work with the present invention is described with respect to  FIGS. 16 and 17 . Endoscope tip  180  contains illumination window  181 , scope observation window  182 , spray nozzle  183 , illumination window  184 , blood content sensor window  185 , front water supply port  186  and utility channel  187 . As seen in  FIG. 17 , the tip of endoscope  180  resides in two planes. The forward portion  189  contains blood content window detector  185  and front water supply port  186 . Because the blood content sensor widow  185  is resident on the forward portion  189 , it is possible to contact the endoscope tip with tissue  188 , without contacting scope observation window  182 . By not contacting the scope observation window  182  with tissue  188 , the image received by the operator is not saturated, and the endoscope image received via scope observation window  182  remains clear and usable. However, because the blood content sensor window  185  is on the forward portion  189 , it may be difficult to rinse it with spray nozzle  183  to remove foreign matter. Instead, front water supply port  186  is used to rinse foreign matter from blood content sensor window  185 . In operation, front water supply port  186  spays water onto tissue  188  and the water is reflected back onto blood content sensor window  185  rinsing away any foreign matter. 
         [0073]      FIG. 18  depicts another exemplary embodiment of an endoscope tip suitable for use with the present invention. In this embodiment, endoscope  2000  contains tip  2004 , illumination window  2001 , scope observation window  2002 , spray nozzle  2003 , and blood content sensor window  2005 . Tip  2004  is generally flat, however, spray nozzle  2003  may be convex and located in a slightly inclined concave portion  2006  of tip  2004 . 
         [0074]    To improve the cleaning process of both the window for scope observation  2002  and blood content sensor window  2005 , the objective lens used for scope observation  2002  and the blood content sensor window  2005  are located in an extended portion of the inclined concave portion  2006 . Spray nozzle  2003 , window for scope observation  2002 , and blood content sensor window  2005  are arranged in the order from lower portion of the incline of  2006  to the higher portion of the slope. In this alignment, water sprayed from spray nozzle  2003  cleans both the window for scope observation  2002 , and blood content sensor window  2005 . The incline  2006  helps guide the water thereby improving cleaning performance, and the substantially flat tip  2004  is less likely to damage the underlying target mucosa. 
         [0075]    While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various changes and modifications may be made without departing from the spirit and scope of the present invention. For example, it is possible to combine the previously described wavelength separation and alternative timing sequencing techniques for scope observation and foreign matter detection in accordance with the invention. Although the blood content sensors used with the invention were described with respect to use with scopes, such as endoscopes or colonoscopes, it should be readily understood that the principles of the invention are equally applicable to blood content sensors employed alone or with other medical instruments.