High resolution digital video colposcope with built
Contents
1. US Pat No 6 587 711 to Alfano et al incorporated herein by reference discloses an apparatus for examining an object such as skin mucosa and cervical tissues for the purpose of detecting cancer and precancerous conditions In one embodiment the apparatus includes a gun shaped hous ing having a handle portion and a barrel portion The front end of the barrel portion is open and a glass cover is mounted therein Red green blue and white LED s are disposed within the handle portion of the housing and are electrically connected to a battery and are also disposed within the handle portion of the housing A manually operable switch for con trolling actuation of each of the four LED s is accessible on the handle portion of the housing An optical fiber is disposed inside the housing and is used to transmit light from the four LED s through a first polarizer disposed in the barrel portion of the housing and then through the glass cover to illuminate 20 30 40 45 6 a desired object Reflected light from the object entering the housing through the glass cover is passed through a second polarizer which is adjustably mounted in the barrel portion of the housing and which is preferably oriented to pass depolar ized light emitted from an illuminated object and is then imaged by optics onto a black and white CCD charged coupled device detector camera The optics may include a lens that is disposed within the barrel portio2. and more compact than the typical illumination sources using either fluorescent or incandescent lighting with bundles of fiber optic cables and LEDs are also more reliable than using either fluorescent or incandescent lights because they are rated for approximately 50 000 hours of use and one million on off cycles As a comparison the rated lifetimes for fluo rescent or incandescent lights are typically less than 10 000 hours with many having a typical lifetime of only 1000 hours LEDs also generate less heat than fluorescent and incandes cent lights Therefore less cooling and less thermal insulation are required for the device housing allowing for smaller power supplies e g smaller fans that produce less noise and vibration for patient and operator comfort The thermal efficiency of LEDs also reduces heat which generates ther mal expansion of the device s mounts and can degrade the optical quality of the images LEDs also require less power and are more efficient in converting electrical power con sumption to visible light ultimately reducing the power con US 8 289 378 B2 9 sumption of the device and enabling battery operation in remote areas if necessary Further light emitted by an LED is also emitted over a broad flat area unlike conventional incan descent and fluorescent lights thus providing for more uni form illumination Moreover as patient safety is of utmost importance in in vivo examinations the fact that
3. includes a focusing subsystem as described in co pending commonly assigned U S patent application Ser No 12 221 267 entitled Single Spot Focus Control filed Jul 31 2008 incorporated herein by reference that utilizes the vertical position of a focused beam of light from e g a laser beam to assess the distance between the device and the examined region in order to achieve optimal focus Preferably the two cameras are able to operate in video mode lower resolution but faster image capture and camera mode maximum reso lution at a lower image capture rate for the acquisition high resolution imagery with all of the diagnostically features present The focusing subsystem is preferably utilized in video mode to achieve satisfactory focus before the invention collects the XP and PP images in camera mode The presently preferred embodiment of the invention also includes a data management system that allows for a com pletely digital data flow simplifying data transfer and storage and minimizing the risk of human error The data manage ment system allows for i the use of image enhancement algorithms ii the use of image processing algorithms iii the use of annotation programs iv digital archiving and v remote viewing This also allows the invention to i perform system diagnostics ii present more comprehensive system 10 20 25 30 35 40 45 50 55 60 65 12 information to the opera
4. respect to imaging systems incorporating polarizing compo nents is that polarization inherently results in a loss of light Because brightness or intensity is an integral part of the achievable contrast i e the difference in visual properties that make an object distinguishable from other objects and the background in the captured images and because the contrast of an image is important in detecting cancer precursors such 20 30 40 45 4 as vascular patterns bright light sources are helpful in pre serving the clarity of an image However these bright light sources must not exceed acceptable thresholds for patient exposure to ultraviolet UV and infrared IR radiation as described by the American Conference on Governmental Industrial Hygienists ACGIH in Threshold Limit Values TLVs for Chemical Substances and Physical Agents and Biological Exposure Indices BEIs Signature Publications 2008 incorporated herein by refer ence Exposure to UV radiation has the potential of acute adverse health effects such as erythema and photokeratitis and can cause DNA damage in the cells Presently the expo sure to UV radiation is minimized if not completely elimi nated by employing a UV blocking filter in the light source beam path prior to the light being available to human viewing and exposure such as described in Welch Allyn Video Col poscope User s manual 2007 incorporated herein by refer ence and S Nakappan
5. to the first polarization orientation Preferably the IPs are integrally formed into a single polarizing element with each LED ina set placed behind a corresponding region having the appropriate polarization The present invention also preferably includes an addi tional separate polarizing element preferably a polarizing beam splitter PBS which simultaneously polarizes and splits an incident beam of light into two beams and directs the split beams towards two cameras detectors so that each camera receives a differently polarized image of the exam ined region Ideally a polarizing beamsplitter splits the beam into two beams that have orthogonal perpendicular polar izations so that the horizontally polarized light or light hav ing a first polarization orientation reflects off the PBS and is directed toward one camera and vertically polarized light or light having a second polarization orientation is transmitted through the PBS toward the second camera Thus when the first set of LEDs is turned on the light passes through an IP to become horizontally polarized light or light having a first polarization orientation which directly illuminates a subject such as tissue or an organ in the field of view Part of the horizontally polarized light reflects off the subject as horizontally polarized glint described below while the other part is partially absorbed by the subject and then reflected as diffuse reflected light describ
6. S Y Park D Serachitopol R Price M Cardeno S Au N Mackinnin C MacAulay M Follen and B M Pikkula Methodology of real time quality control for the multispectral digital colposcope Gynecologic Oncol ogy 107 S21 S222 2008 incorporated herein by reference Many bright light sources also contain a large amount of IR which is essentially excess heat Similar to UV radiation the exposure to IR radiation is minimized or eliminated by the utilization ofan IR blocking filter Although the heat exposure of the user or patient is minimized or eliminated by an IR blocking filter the heat generated by the IR radiation puts stress on the optical and mechanical components of the light source assembly and may significantly decrease the lifetime of the components as well as of the light source itself Further some bright light sources require a long start up time before the output intensity is stable This means there is a wait time before the device can be utilized in a clinical examination possibly decreasing the cost effectiveness of such a device A third factor contributing to poor cervical imagery is non uniform lighting which can lead to non uniformity of the brightness or intensity in the resulting image Non uniformity of brightness impairs the potential accuracy of any diagnosis based on the resulting image The following patents may be considered relevant to the field of the present invention USS Pat No 4 979 498 to
7. a side view thereof FIG 7A is a side conceptual view of the detection system for a two camera system and FIG 7B is a side conceptual view of the detection system for a one camera system FIGS 8A 8B and 8C are schematics of the focusing subsystem which show the camera object plane the camera and the position of the focused light relative to the cervix for three different focus states In FIG 8A the cervix is in focus in FIG 8B the cervix is too close and in FIG 8C the cervix is too far FIG 9 is a flow chart of the data management system US 8 289 378 B2 13 BEST MODE FOR CARRYING OUT THE INVENTION Initially a subject 72 such as an organ or tissue in a field of view is directly illuminated by the presently preferred embodiment s illumination subsystem as shown in FIG 1 The purpose of the illumination subsystem is to provide even and direct illumination of the subject in the field of view with sufficient intensity brightness for the invention to acquire images quickly enough to avoid or minimize blur due to motion for e g patient movement The illumination sub system preferably comprises the following main compo nents a front lens 34 b illumination polarizer IP 36 c LED lenses 42 d one or more sets of LEDs 49 e illumi nation board 50 with control electronics and f power supply 15 The laser 51 of the focusing system is also shown as is the subject 72 being illuminated and the light beam
8. illumina 20 25 30 35 40 45 50 55 60 65 14 tion Again a person of ordinary skill in the art could easily design the LED configuration for a number of LEDs other than 2 4 and 8 for example 6 10 12 14 etc FIG 5A and FIG 5B illustrate the process of cross polar ization in the preferred embodiment of the invention The presence of light with a polarization orientation perpendicu lar to the plane of the paper horizontally polarized light is indicated by an O e g 70 and the presence of light with a polarization orientation parallel to the plane of the paper vertically polarized light is indicated by an up and down arrow e g 82 The presence of both an O and an up and down arrow denotes unpolarized light e g 66 As illustrated in FIG 5A XP and PP images are obtained by illuminating a field of view with unpolarized light 66 from at least one set of LEDs 49 which is filtered through an IP 36 to produce horizontally polarized light or any light having a first polarization orientation 70 When the horizontally po larized light 70 interacts with a subject 72 such as cervical tissue in the field of view it partially penetrates the tissue and is also partially reflected as horizontally polarized glint or glint having a first polarization orientation A portion of the light that penetrates the tissue will gradually become unpolarized and reflect from the tissue as diffuse ref
9. medical image storage is pres ently DICOM Digital Imaging and Communications in Medicine This data management system allows for a completely digital data flow simplifying data transfer and storage and minimizing the risk of human error The data management system allows for i the use of image enhancement algo rithms ii the use of image processing algorithms iii the use of annotation programs iv digital archiving and v remote viewing This also allows the invention to i perform system diagnostics ii present more comprehensive system information to the operator and technicians and iii include comprehensive information with respect to each image data set about the state of the system when the images were acquired It also preferably contains a fully integrated user interface in which physical buttons are tied to the hardware and software platforms permitting the functionality of the device to adapt if necessary to new functions INDUSTRIAL APPLICABILITY This invention uses LEDs and cross polarization to pro duce bright high resolution digital images both with and without glint that preserves image clarity while suppressing glint and creates both cross polarized images glint free images and parallel polarized images images with glint preferably at multiple magnifications The invention is appli cable to any imaging device in which it is desirable to enhance visualization of a subject such as tissue or
10. method is directed to the steps of encoding a periodic pattern of illumination preferably with a fluorescent excitation wave length when exposing a turbid medium to the periodic pat tern to provide depth resolved discrimination of structures within the turbid medium and reconstructing a non contact three dimensional image of the structure within a turbid medium As a result wide field imaging separation of the average background optical properties from the heterogene ity components for a single image separation of superficial features from deep features based on selection of spatial US 8 289 378 B2 7 frequency of illumination or qualitative and quantitative structure function and composition information is extracted from spatially encoded data U S Patent Application No 2006 0215406 to Thrailkill incorporated herein by reference discloses a medical diag nostic instrument which could be a colposcope for examin ing cervical tissue and includes a light source comprising an annular array of high intensity light emitting diodes LEDs The LED array includes a central access opening which pro vides viewing access for the colposcope optical components to the illumination site The array includes a plurality of sets of LEDs with each set including a red blue and green emit ting LED The intensities of the red blue and green LEDs respectively are controllable with a controller to continu ously vary or tune the spectral ch
11. move the device to achieve optimal focus Although the focus light source 51 is shown to be located below the optical axis 60 in FIG 8A FIG 8B and FIG 8C it can be positioned anywhere off the optical axis The system is operable as long as the focus beam and the optical axis are within a certain angle LI of each other and the focus beam is not obstructed by any object other than the region of interest The focus system is operable when the angle a is approximately between the ranges of 2 to 60 degrees Preferably the angle a should be approximately in the range of 4 to 15 degrees Optimally the angle should be approximately in the range of 5 to 8 degrees 0 an 5 25 30 40 45 60 16 The presently preferred embodiment of the invention also includes a data management system FIG 9 shows a flowchart of the data management system The data management sys tem 3 includes a database of image and patient data and interacts with the data acquisition system 7 and external sources such as PACS Picture Archiving and Communica tion System 10 pathology reports 11 patient data records 12 telemedicine applications 13 and optional other sources defined by the user 14 PACS refer to computers or networks dedicated to the storage retrieval distribution and presenta tion of images The medical images are preferably stored in a format that is independent of this invention and widely used The most common format for
12. preferably designed to capture a full field of view of the subject and the secondary optics of the second camera 24 are preferably designed to capture a mag nified view of a smaller region of interest typically being able to resolve the smallest diagnostically relevant feature In the preferred embodiment which uses two sets of LEDs the optical paths of the two sets of LEDs are polarized perpen dicular to one another after being split by the PBS 22 and depending on which set of LEDs is turned on the image outputs received and displayed by both cameras will be either i a full view XP image ii a magnified region of interest view PP image iii a full view PP image or iv a magnified region of interest XP image The PP and XP images are sub stantially co registered because of the rapid switching between or switching on and off of the illumination source LEDs and can be used in conjunction with each other for diagnostic purposes for example fading between them In the embodiment which uses only one set of LEDs the optics of the two camera systems 20 and 24 are preferably designed to capture the same field of view of the subject this view being either the full view or a magnified region of interest view Here the image outputs received and displayed will be either i a full view or magnified XP image or ii a full view or magnified PP image For a single one camera system as seen in FIG 7B the optics of the camera 2
13. still image data 9 Claims 9 Drawing Sheets U S Patent Oct 16 2012 Sheet 1 of 9 US 8 289 378 B2 FIG 1 U S Patent Oct 16 2012 Sheet 2 of 9 US 8 289 378 B2 FIG 2B 36 FIG 2C U S Patent Oct 16 2012 Sheet 3 of 9 US 8 289 378 B2 Ie el e k gt S Ma9 He 36 FIG 3A 34 e ety Se 36 FIG 3B 34 Wa 36 U S Patent Oct 16 2012 Sheet 4 of 9 US 8 289 378 B2 an Y a i gt FIG 4A FIG 4C U S Patent Oct 16 2012 Sheet 5 of 9 US 8 289 378 B2 FIG 5A FIG 5B U S Patent Oct 16 2012 N 7 83 FIG 6A Sheet 6 of 9 US 8 289 378 B2 86 85 84 FIG 6B U S Patent Oct 16 2012 Sheet 7 of 9 US 8 289 378 B2 20 34 22 24 FIG 7A 34 22 24 FIG 7B U S Patent Oct 16 2012 Sheet 8 of 9 US 8 289 378 B2 U S Patent Oct 16 2012 Sheet 9 of 9 US 8 289 378 B2 US 8 289 378 B2 1 HIGH RESOLUTION DIGITAL VIDEO COLPOSCOPE WITH BUILT IN POLARIZED LED ILLUMINATION AND COMPUTERIZED CLINICAL DATA MANAGEMENT SYSTEM This application claims priority to U S provisional patent application No 61 137 684 for CervicalMD C30 Imaging Subsystem filed on Aug 1 2008 TECHNICAL FIELD This invention relates to medical imaging and more spe cifically to a device and process that suppresses specular reflection glint through cross polarization producing bright cross polarized and parallel polarized images at multiple magnifications in real time there
14. the spectral emission of LEDs unlike fluorescent lights does not contain a significant amount of ultraviolet UV light is extremely beneficial This fact eliminates the need for the present invention to utilize UV filters detectors and hardware all of which are used in con junction with UV emitting light sources to monitor measure control or minimize UV output to prevent UV damage to the examined region The inventors are unaware of any other imaging device that incorporates the advantages of rapidly switching between different sets of LEDs to instantly directly and uniformly illuminate a field of view for near simultaneous imaging of tissue or an organ and cross polarization to suppress the negative effects of glint without compromising the brightness of the image s The first presently preferred embodiment of the invention preferably uses two sets of LEDs Each LED in a set has a separate non moving fixed or stationary illumination polar izer IP in front of it with the fixed IP in front of each of the LEDs in the first set having a horizontal orientation or being horizontally polarized it does not have to be a horizontal orientation but can be any first polarization orientation and the fixed IP in front of each of the LEDs in the second set having a vertical orientation or being vertically polarized it does not have be a vertical orientation but can be any second polarization orientation which is substantially perpendicular
15. 0 45 50 55 60 65 8 The present invention is a device that preferably creates pairs of clear images a glint free image cross polarized image and an image with glint parallel polarized image at multiple magnifications The term cross polarized XP refers to when a first polarization orientation is perpendicular to a second polarization orientation whereas the term paral lel polarized PP refers to when a first polarization orienta tion is parallel to a second polarization orientation In the present invention PP can also mean singly polarized where there is only one polarization orientation or unpolarized The XP and PP images can be used in conjunction with each other for diagnostic purposes For example XP and PP images can be registered aligned and then faded into each other to aid a clinician in cancer detection as described in co pending commonly assigned U S patent application Ser No 12 228 298 entitled A Method of Image Manipulation to Fade Between Two Images filed Aug 11 2008 incorporated herein by reference Fading between the two images allows aclinician to detect important features that may be masked by glint while at the same time retaining to a desired extent the natural and three dimensional shape of tissue or an organ such as the cervix in the image To suppress glint the first preferred embodiment prefer ably employs cross polarization which allows for deeper layers of tissue t
16. 4 are preferably either a fixed focal length lens configured to capture the full field of view of the subject or a zoom lens configured to capture the full field of view of the subject as well as a magnified view of the subject The presently preferred embodiment of the invention also includes a focusing subsystem which helps achieve optimal focus of the images This focusing subsystem analyzes images taken in the video mode to assess if the invention is in focus before images are acquired in camera mode As dis played in FIGS 8A 8B and 8C a focus light source e g a focused LED or a laser 51 produces a focus beam 53 that is focused toward the optical axis 60 through a lens 34 the displacement of the focus beam Ay in the field of view of the camera uniquely determines the distance Az needed to align the examined region region or object of interest 72 with the camera object plane 62 where the focus beam 53 meets the optical axis 60 When the examined region is aligned with the camera object plane as seen in FIG 8A the examined region is in focus When the focus beam is in the lower pixels of the image the examined region is too close as shown in FIG 8B and the subsystem is out of focus When the focus beam is in the upper pixels of the image the examined region is too far as seen in FIG 8C and the subsystem is also out of focus The output of the focusing subsystem suggests which direction the operator should
17. Oneda et al incorporated herein by reference discloses a video cervicoscope system for the examination of the cervix comprising a rigid elongated tubular member having a light guide imaging means at the distal end of said tubular member a disposable light trans mitting sleeve disposed about the distal end of said tubular member and transmitting means to transmit an image viewed by said imaging means proximally to a control box wherein said image is received and stored USS Pat No 5 836 872 to Kenet et al incorporated herein by reference discloses a method for monitoring a region of a body surface which includes recording at a first time a first multispectral digital image of the surface including the region recording at a subsequent time a subsequent multi spectral digital image of the surface including the region and comparing the first and the subsequent images Also such a method in which the first and subsequent images are high magnification images and further including recording low magnification images that include the high magnification images Also disclosed is a method for forming a diagnosti cally useful classification of pigmented skin lesions using such a method to construct a database containing quantita tively extracted selected features from images recorded from a plurality of skin lesions and correlating the features from US 8 289 378 B2 5 each such lesion in the database with the medical history of t
18. a side view thereof As seen in FIGS 6A and 6B each camera preferably comprises the following components an imaging sensor 83 a lens mount 84 an output cable connector housing 85 and an output cable connector 86 The sensor 83 is preferably able to run in two modes of operation video mode and camera mode In video mode the operator manipulates the device much like a regular video camera for positioning and manual focus In this mode a low resolution high frame rate image stream is produced In camera mode the present invention will tempo rarily change the imaging sensor settings so that the highest possible image resolution is preferably achieved at the expense of a lower frame rate The final XP and PP images of the present invention are preferably acquired in camera mode and are stored for later review image annotation and pro cessing XP and or PP images can also be registered aligned and then faded into each other to aid a clinician in arriving at a diagnosis FIG 7A shows a side view ofa presently preferred embodi ment of the detection system which contains two cameras US 8 289 378 B2 15 and FIG 7B shows a side view of another embodiment of the detection system which contains only one camera The place ment of the front lens 34 polarizing element such as a polarizing beam splitter 22 and the cameras 20 and 24 are shown therein For a two camera system as seen in FIG 7A the optics of the first camera 20 are
19. al detection system for in vivo identification and localization ofcervical intra epithelial neoplasia J Biomed Optics 11 3 034009 1 12 2006 and J E Kendrick W K Huh and R D Alvarez LUMA Cer vical Imaging System Expert Rev Med Devices 4 2 121 129 2007 incorporated herein by reference By illuminating the cervix at different angles and acquiring several images the position of the glint on the surface ofthe cervix is different between the different images and the images can be com bined to create a glint free combined image The use of polarization filters each of which functions in the same way as a pair of polarized sunglasses is another glint reducing or eliminating technique well known in the art see for example E Hecht Optics Addison Wesley 1st edition 1972 2nd edition 1987 3rd edition 1997 4th edition 2001 The polarization filter method utilizes one polarization filter placed at the light source and another filter rotated to approxi mately 90 positioned in front of the detector By applying this cross polarization scheme the reflections from the sur face of the object under study are substantially minimized if not completely eliminated and the end result is an essentially glint free object or image Cross polarization is employed for example in commercially available colposcopes Welch Allyn Video Colposcope User s manual 2007 incorporated herein by reference and research colposcope syste
20. an organ ina field of view by using at least one image with glint and a glint free image What is claimed is 1 A device for enhancing visualization of tissue ina field of view comprising a first set of LEDs to emit light onto said field of view whereby when said first set of LEDs is turned on said first set of LEDs emits light onto said field of view through a first illumination polarizer placed between said first set of LEDs and said field of view to create polarized light in said field of view having a first polar ization orientation and wherein said polarized light hav ing said first polarization orientation is reflected by said tissue as first total reflected light a second set of LEDs to emit light onto said field of view whereby when said second set of LEDs is turned on said second set of LEDs emits light onto said field of view through a second illumination polarizer placed between said second set of LEDs and said field of view to create polarized light in said field of view having a second polarization orientation and wherein said polarized light having said second polarization orientation is reflected by said tissue as second total reflected light wherein said first set of LEDs and said second set of LEDs all emit visible light of the same color US 8 289 378 B2 17 wherein said second polarization orientation is substan tially perpendicular to said first polarization orientation apolarizing element to receiv
21. ance the visualization of tissue BRIEF DESCRIPTION OF DRAWINGS FIG 1 is aconceptual side view of the main components of the illumination system FIGS 2A 2B and 2C are conceptual front views of the illumination system illustrating the configuration for two sets of LEDs FIG 2A shows a configuration containing a total of 8 LEDs FIG 2B shows a configuration containing a total of 4 LEDs and FIG 2C shows a configuration containing a total of 2 LEDS FIGS 3A 3B and 3C are conceptual front views of the illumination system illustrating the configuration for one set of horizontally polarized or having a first polarization direc tion LEDs FIG 3A shows a configuration containing a total of 8 LEDs FIG 3B shows a configuration containing a total of 4 LEDs and FIG 3C shows a configuration containing a total of 2 LEDS FIGS 4A 4B and 4C are conceptual front views of the illumination system illustrating the configuration for one set of vertically polarized or second polarization direction LEDs FIG 4A shows a configuration containing a total of 8 LEDs FIG 4B shows a configuration containing a total of 4 LEDs and FIG 4C shows a configuration containing a total of 2 LEDS FIGS 5A and 5B are conceptual views of the preferred embodiment to illustrate the process of cross polarization FIG 5A shows a two camera system and FIG 5B shows a single camera system FIG 6A is a front view of one of the camera systems and FIG 6B is
22. aracteristics of the illumi nation from the light source Selected color mixes can be stored in a memory for later retrieval U S Patent Publication No 2007 0213590 to Squicci narini incorporated herein by reference discloses a portable multi functional endoscopic device and method for use in the examination of tissue to permit diagnostic therapeutic or anatomical assessment data to be transmitted recorded or analyzed The device includes a base unit sized and config ured to be held in a human hand to permit functional and directional control of the device an interchangeable head assembly sized and configured to be inserted into an orifice being removably connectable to the base unit and an inflat able tissue stabilizer disposed external to a distal end of the device In preferred aspects the endoscopic device has an image sensor light source lens air pump and working tools U S Patent Application No 2008 0049997 to Chin incor porated herein by reference discloses an image enhancement system that includes a data source which provides image data of an object enhancement data storage including image enhancement information an image enhancement unit con figured to enhance the image data based on the image enhancement information and a color display configured to display a monochrome image representing the enhanced image data on a screen thereof The enhanced image data may include a gray level scale of at least 32 bits per pi
23. as incorporated herein by reference discloses a method and an apparatus for the in vivo non invasive early detection of alterations and mapping of the grade of these alterations caused by the biochemical and or the functional characteris tics of epithelial tissues during the development of tissue atypias dysplasias neoplasias and cancers The method is based on the simultaneous measurement of the spatial tem poral and spectral alterations in the characteristics of the light that is re emitted from the tissue under examination as a result of a combined tissue excitation with light and special chemical agents The topical or systematic administration of these agents results in an evanescent contrast enhancement between normal and abnormal areas of tissue The apparatus enables the capturing of temporally successive imaging in one or more spectral bands simultaneously Based on the measured data the characteristic curves that express the agent tissue interaction kinetics as well as numerical param eters derived from these data are determined in any spatial point of the examined area Mapping and characterization of the lesion are based on these parameters U S Patent Publication No 2006 0184043 to Tromberg et al incorporated herein by reference discloses an improve ment in a method for quantitative modulated imaging to per form depth sectioned reflectance or transmission imaging ina turbid medium such as human or animal tissue The
24. az United States Patent Soto Thompson et al US008289378B2 US 8 289 378 B2 Oct 16 2012 0 Patent No 45 Date of Patent 54 HIGH RESOLUTION DIGITAL VIDEO COLPOSCOPE WITH BUILT IN POLARIZED LED ILLUMINATION AND COMPUTERIZED CLINICAL DATA MANAGEMENT SYSTEM 75 Inventors Marcelo Esteban Soto Thompson Honolulu HI US Andrew Beaumont Whitesell Honolulu HI US Ulf Peter Gustafsson Honolulu HI US 73 Assignee STI Medical Systems LLC La Jolla CA US Notice Subject to any disclaimer the term of this patent is extended or adjusted under 35 U S C 154 b by 947 days 21 Appl No 12 291 890 22 Filed Nov 14 2008 65 Prior Publication Data US 2010 0026785 Al Feb 4 2010 Related U S Application Data 60 Provisional application No 61 137 684 filed on Aug 1 2008 51 Int Cl HOAN 132 02 2006 01 92 USCh aiitra 348 47 348 57 348 58 58 Field of Classification Search 0 0 000 348 47 See application file for complete search history 56 References Cited U S PATENT DOCUMENTS 5 929 443 A 7 1999 Alfano et al 6 766 184 B2 7 2004 Utzinger et al 2006 0184040 Al 8 2006 Keller etal oo 600 476 2006 0215406 A1 9 2006 Thrailkill OTHER PUBLICATIONS D G Ferris et al Modern Colposcopy Textbook and Atlas pp 250 662 American Society for Colposcopy and Cervical Pathology Kendall Hunt Publishing Co Dubuque Iowa B S Apgar et al Co
25. by enhancing the visualiza tion of diagnostically relevant features within a subject such as organs or tissue The device also preferably includes a focusing subsystem and a computerized data management system for archival purposes and for the annotation of digital data BACKGROUND ART Although this invention is being disclosed in connection with cervical cancer it is applicable to many other areas of medicine Uterine cervical cancer is the second most common cancer in women worldwide with nearly 500 000 new cases and over 270 000 deaths annually IARC Globocan 2002 database International agency for research in cancer 2002 incorporated herein by reference Because invasive disease is preceded by pre malignant Cervical Intraepithelial Neopla sia CIN if detected early and treated adequately cervical cancer can be universally prevented D G Ferris J T Cox D M O Connor V C Wright and J Foerster Modern Col poscopy Textbook and Atlas pp 1 699 American Society for Colposcopy and Cervical Pathology 2004 incorporated herein by reference Colposcopy is the primary diagnostic method in the United States to detect CIN and cancer follow ing an abnormal cytological screen Papanicolaou smear or pap smear The purpose of a colposcopic examination is to identify and rank the severity of lesions so that biopsies representing the highest grade abnormality can be taken if necessary The biopsies are then microscopi
26. cally evaluated by a pathologist based on the morphology of the tissue For the colposcopic exam an optical colposcope is typi cally used and has been used for such purposes for almost 80 years A colposcope is a binocular microscope with a built in white light source and objective lens attached to a support mechanism B S Apgar Brotzman G L and Spitzer M Colposcopy Principles and Practice W B Saunders Com pany Philadelphia 2002 incorporated herein by reference At low levels of magnification comparable to a circular field of view of approximately 50 to 100 mm the entire vagina and cervix can be visualized and this setting is typically used to obtain a general impression of the surface structure and archi tecture Medium magnifications comparable to a circular field of view of approximately 15 30 mm and high magnifi cations comparable to a circular field of view of approxi mately 5 15 mm are utilized for detailed analysis of the vagina and the cervix These higher magnifications are often necessary to detect and identify certain vascular patterns indicative of the presence of more advanced pre cancerous or cancerous lesions During the colposcopic exam acetic acid and iodine solutions are usually applied to the surface of the cervix to improve the visualization of abnormal areas In 20 25 30 35 40 45 50 55 60 65 2 addition different colored filters are often used to accentuate blood ve
27. d said second illumination polarizer are preferably integrally formed 5 A device according to any one of claim 1 or 3 wherein said first camera is at a first magnification and said second camera is at a second magnification wherein said second magnification is greater than said first magnification 6 A device according to any one of claim 1 2 or 3 further comprising a focusing subsystem to achieve optimal focus 7 A device according to any one of claim 1 2 or 3 further comprising a computerized data management system for archival purposes and for the annotation of digital data 8 A process to suppress glint and preserve image clarity comprising view comprising a first set of LEDs to emit light onto said field of view whereby when said first set of LEDs is turned on said 30 first set of LEDs emits light onto said field of view through a first illumination polarizer placed between said first set of LEDs and said field of view to create polarized light in said field of view having a first polar ization orientation and wherein said polarized light hav 35 ing said first polarization orientation is reflected by said tissue as first total reflected light a second set of LEDs to emit light onto said field of view whereby when said second set of LEDs is turned on said second set of LEDs emits light onto said field of view 40 through a second illumination polarizer placed between said second set of LEDs and said field of view
28. d to polarize the light from each set of LEDs 49 such that the second polarization orientation is substantially perpendicular to the first polarization orienta tion FIG 2A FIG 2B and FIG 2C illustrate the use of 8 4 and 2 LEDs respectively to achieve illumination with light of perpendicular polarization orientations For two sets of LEDs 49 with perpendicular polarization orientations i e two polarization orientations the configuration will preferably be designed with the total number of LEDs as a multiple of 2 to ensure similar intensity brightness and uniform illumi nation for both polarization orientations Although not shown in FIG 2A 2C a person of ordinary skill in the art could easily design the LED configuration for additional LEDs such as 6 10 12 14 etc The circular design and alternating polarization orientation of the LEDs 49 will ensure uniform illumination for both polarization orientations FIGS 3A 3C and FIGS 4A 4C illustrate an alternative embodiment which uses only one set of LEDs 49 the direc tion of the arrows again designating the polarization orienta tion of the light from the LED Here the IP 36 is designed to polarize the light from the LEDs 49 in a single polarization orientation only FIG 3A FIG 3B and FIG 3C and FIG 4A FIG 4B and FIG 4C illustrate the use of 8 4 and 2 LEDs respectively Here any number of LEDs can be used however a circular configuration will again ensure uniform
29. direction 70 of the illumination system The LEDs 49 are preferably mounted onto the illumination board 50 which also provides control electronics to set the operating current and voltage and to rapidly turn the LEDs 49 on and off The LED lenses 42 focus the divergent light from the unpolarized LED 49 into light output beams 66 An IP 36 is placed in front of the LED lenses 42 The front lens 34 directs the polarized LED light output 70 towards the subject 72 to illuminate the entire field of view that contains the subject 72 Front views of the illumination system showing the LEDs 49 IP 36 and front lens 34 are displayed in FIG 2A 2C FIG 3A 3C and FIG 4A 4C Configurations for two sets of LEDs are illustrated in FIG 2A 2C whereas configurations for one set of LEDs are illustrated in FIG 3A 3C and FIG 4A 4C The polarizing direction of the light is indicated by the arrows FIGS 2A 2C illustrate the preferred embodiment using two sets of LEDs 49 the solid arrows designating the first set of LEDs 49 and the outlined arrows designating the second set of LEDs 49 The direction of the arrows designates the polarization orientation of the LED light 70 after being trans mitted by the IP 36 The outlined arrows have a horizontal polarization orientation or a first polarization orientation and the solid black arrows have a vertical orientation or a second polarization orientation For two sets of LEDs 49 the IP 36 is preferably designe
30. e said first total reflected light and said second total reflected light and split said total 18 3 A device for enhancing visualization of tissue ina field of view comprising a first set of LEDs to emit light onto said field of view wherein all LEDs in said first set of LEDs emit visible reflected light into a first parallel polarized output anda 5 light of the same color first cross polarized output when said first set of LEDs is an illumination polarizer placed between said first set of illuminated and a second parallel polarized output and LEDs and said field of view to cause said light emitted a second cross polarized output when said second set of onto said field of view to become horizontally polar LEDs is illuminated ized light wherein said horizontally polarized light is a first camera to receive said first parallel polarized output 10 reflected by said tissue as total reflected light to create a first parallel polarized image when said first a polarizing element to receive said total reflected light that set of LEDs is illuminated and to receive said second both polarizes and splits said total reflected light into cross polarized output to create a second cross polar first and second beams of light which contain substan ized image when said second set of LEDs is illuminated tially perpendicular polarization orientations to one a second camera to receive said first cross polarized output 15 another wherein one of said polarizat
31. ects the horizontally polarized glint and any other diffuse reflected light that has a horizontal orientation a first PP output to a first camera which creates a first PP image The second beam of light split by the PBS contains any diffuse reflected light with a polarization orientation that is substantially perpendicular to the first beam a first XP out put and is directed to a second camera which creates a first XP image For all preferred embodiments of the invention the PP image will always be created from the split beam of light which contains glint whereas the XP image will be created from the split beam of light that does not contain glint Alternatively when the second set of LEDs is turned on the light passes through an IP to become vertically polarized light or any light having a second polarization orientation where the second polarization orientation is substantially per pendicular to the first polarization orientation This time the second total reflected light will contain vertically polarized glint or glint having a second polarization orientation and diffuse reflected light The PBS will now split the second total reflected light into a second PP output and a second XP output and direct the second PP output vertically polarized glint and any diffuse reflected light that has a vertical orien tation to the second camera which creates a second PP image The second XP output any total reflected light that has a horizo
32. ed below The reflected glint maintains its horizontal polarization or first polarization orientation to become horizontally polarized glint or glint having a first polarization orientation The light that penetrates the tissue will gradually become unpolarized after a sufficient number of scattering events and a portion will be reflected from the tissue as diffuse reflected light The first total reflected light reflected by the subject thus contains horizontally polarized glint or glint having a first polariza tion orientation and diffuse reflected light While glint refers to light that is reflected off one surface e g the surface of the 20 25 30 35 40 45 50 55 60 65 10 cervical tissue in one direction e g towards one of the cameras diffuse light refers to light that is scattered in all directions and is unpolarized It is well known in the art that unpolarized light can be described as a combination of both PP and XP light Because a camera captures only that portion of the diffuse light that is reflected in the camera s direction the diffuse reflected light does not have the same visually impairing effect i e glare on the image as glint When the first total reflected light reaches the PBS that beam splitter both polarizes and splits the light into first and second beams of light which contain substantially perpen dicular polarization orientations to one another The PBS preferably dir
33. ffuse reflected light When the total reflected light reaches the PBS the PBS preferably directs the horizontally polarized glint and any diffuse reflected light having a horizontal orientation PP output to the first camera which creates the PP image and directs any diffuse reflected light having a vertical orientation XP output to the second camera which creates the XP image By adding zoom control to the cameras PP and XP images at different magnifications can be acquired A fourth preferred embodiment is simpler than all of the previously described embodiments It uses only one set of LEDs and one camera The fourth preferred embodiment emphasizes the collection of glint free XP images only Again the device polarizes unpolarized light from the single set of LEDs by passing the unpolarized light through an IP to create horizontally polarized light or light having a first polarization orientation to illuminate a subject in a field of view The horizontally polarized light that interacts with the subject is reflected as total reflected light that includes hori zontally polarized glint and diffuse reflected light When the total reflected light reaches the PBS it directs any diffuse reflected light having a vertical orientation XP output to the camera which creates the XP image By adding zoom control to the camera system XP images at different magnifications can be acquired The presently preferred embodiment of the invention also
34. he skin lesion from which the image was recorded Further a method for diagnosis of a premelanomatous or early mela nomatous condition includes using the method for character izing a surface region including the lesion and comparing the features of the lesion so obtained with the features in a data base obtained from a number of skin lesions including lesions known to be premelanomatous or early melanomatous or classifying the features of the lesion according to the diag nostically useful classification of pigmented skin lesions U S Pat No 5 929 443 to Alfano et al incorporated herein by reference discloses a method and apparatus for the imaging of objects based on the polarization and depolariza tion of light In one embodiment a surface of a turbid medium is imaged by illuminating the surface of the turbid medium with light whereby light is backscattered from the illumi nated surface of the turbid medium detecting a pair of complementary polarization components of the backscat tered light and forming an image of the illuminated surface using the pair of complementary polarization components The illuminating light is preferably polarized e g linearly polarized circularly polarized elliptically polarized where for example the illuminating light is linearly polarized the pair of complementary polarization components are prefer ably the parallel and perpendicular components to the polar ized illuminating light and the i
35. ion orientations is to create a first cross polarized image when said first set substantially parallel to polarization of said horizon of LEDs is illuminated and to receive said second par tally polarized light and the other of said polarization allel polarized output to create a second parallel polar orientations is substantially perpendicular to polariza ized image when said second set of LEDs is illuminated tion of said horizontally polarized light whereby said electronic switching means to rapidly switch between illu 20 polarizing element receives said total reflected light and minating said first set of LEDs and illuminating said splits said total reflected light into a parallel polarized second set of LEDs to reduce influence from patient output and a cross polarized output movement between successive images allowing for bet a first camera to receive said cross polarized output to ter registration between said successive images and create a cross polarized image whereby said parallel polarized images and said cross 25 asecond camera to receive said parallel polarized output to polarized images enhance visualization of said tissue 2 A device for enhancing visualization of tissue in a field of create a parallel polarized image and whereby said cross polarized image and said parallel po larized image enhance visualization of said tissue 4 A device according to any one of claim 1 or 2 wherein said first illumination polarizer an
36. l as automation of the workflow associated with colposcopy The system could simplify the administration of patient data and history allow the use of electronic patient data records and interface and integrate with standard systems for handling storing printing and transmitting information in medical imaging such as DICOM Digital Imaging and Communication in Medicine DICOM is a standard for handling storing print ing and transmitting information in medical imaging It includes a file format definition and a network communica tions protocol The communication protocol is an application protocol that uses TCP IP the standard internet protocol to communicate between systems DICOM files can be exchanged between two entities that are capable of receiving image and patient data in DICOM format Digital imaging alone is also a pre requisite for telemedicine applications further increasing the availability of screening and detection in rural areas and developing countries In order to reliably assess colposcopic features the imag ery upon which a CAD system operates must be ofhigh visual quality One factor contributing to poor cervical imagery is specular reflection glint which is perfect mirror like reflection of light from a surface in which light from a single incoming direction i e a ray is reflected into a single out going direction Glint is undesirable because it effectively eliminates color information in an image and a
37. larized output and a cross polarized output rapidly electronically switching between said parallel po larized output and said cross polarized output to reduce influence from patient movement between successive images allowing for better registration between succes sive images 20 collecting said rapidly electronically switched cross polar ized outputs producing a set of cross polarized images from said cross polarized outputs and whereby said set of cross polarized images enhances visu alization of said tissue by removing glint to allow for deeper layers of said tissue to be visualized at multiple magnifications
38. lected light The total reflected light 74 will be a combination of both i the horizontally polarized glint and ii the diffuse reflected light When the total reflected light 74 reaches an additional polarizing element designed to split the light into perpendicular orientations such as a polarizing beam splitter or PBS 22 it splits the total reflected light into a PP output 76 and a XP output 82 that are received by separate cameras 20 and 24 The PP output creates the PP image and contains horizontally polarized glint and any diffuse reflected light having the same polarization horizontally polarized diffuse reflected light The PP image will look substantially similar to standard colposcopic data The other output the XP output is vertically polarized vertically polarized does not mean the light has to be vertically polarized but can be any light having a second polarization orientation that is at a substantial angle to the first polarization described above preferably substantially perpendicular and contains only the diffuse reflected light having the same vertical polarization but no glint Thus a first camera 20 creates a PP image and a second camera 24 creates the XP image FIG 5B illustrates the concept of using one camera 24 only and thus acquiring an XP image only FIG 6A and FIG 6B illustrate the camera configuration of the presently preferred embodiment FIG 6A is a front view of one of the cameras and FIG 6B is
39. lly switched parallel po create a cross polarized image when one of said set of larized outputs and said cross polarized outputs LEDs is illuminated and to receive one of said parallel producing a set of cross polarized images from said cross polarized outputs to create a parallel polarized image polarized output and a set of parallel polarized images when the other set of LEDs is illuminated 60 from said parallel polarized outputs and electronic switching means to rapidly switch between illu minating said first set of LEDs and illuminating said second set of LEDs to reduce influence from patient movement between successive images allowing for bet ter registration between said successive images and whereby said cross polarized image and said parallel po larized image enhance visualization of said tissue whereby said set of cross polarized image and said set of parallel polarized images can be registered and faded into each other to enhance visualization of said tissue 9 A process to suppress glint and preserve image clarity 65 comprising polarizing unpolarized light from LEDs to produce polar ized light having a first polarization orientation US 8 289 378 B2 19 illuminating a field of view containing tissue with said polarized light having a first polarization orientation reflecting said polarized light off said tissue as total reflected light polarizing and splitting said total reflected light into a parallel po
40. lposcopy Principles and Practice pp 115 132 W B Saunders Company Philadelphia PA 2002 K T Schomacker et al Novel optical detection system for in vivo identification and localization of cervical intra epithelial neoplasia J Biomed Optics 11 3 pp 034009 1 to 034009 02 2006 J E Kendrick et al LUMA Cervical Imaging System Expert Rev Med Devices 4 2 pp 121 129 2007 E Hecht Optics pp 270 332 Addison Wesley 2nd edition 1987 Welch Allyn Video Colposcope Directions for Use 2007 S Nakappan et al Methodology of real time quality control for the multispectral digital colposcope Gynecologic Oncology 107 S21 222 2008 Acgih Electromagnetic Radiation and Fields pp 13 43 2007 Cincinati OH cited by examiner Primary Examiner Tonia L Dollinger Assistant Examiner Adam Cooney 74 Attorney Agent or Firm Martin E Hsia 57 ABSTRACT This invention uses LEDs and cross polarization to produce bright high resolution digital images both with and without glint which adversely affects the clarity of standard colpo scopic images as well as streaming video at lower resolu tion The invention allows for deeper layers of the tissue to be more efficiently visualized at multiple magnifications thereby enhancing the invention s diagnostic capabilities and it includes a focusing subsystem and a computerized data management system to archive and annotate
41. lso results in the introduction of artifacts misrepresentations of tissue structures in the image Glint eliminates color information because its mirror like reflection shows the color of the light source and not of the underlying tissue much as a mirror shows the color of a reflected light and not the color of the mirror itself Because this color information may be impor tant in detecting cancer precursors reducing the amount of glint in an image is helpful in producing high quality images for diagnostic purposes However it is not always desirable to eliminate all the glint from an image because an image of a tissue or organ that contains glint may look more natural and three dimensional In addition colposcopists analyze the glint patterns on the cervix to assess the surface contour of lesions an important feature used to evaluate lesion severity US 8 289 378 B2 3 The prior art describes a number of ways to reduce the influence of or eliminate glint Physicians using optical col poscopes can change their field of view and or the lightning conditions to either move the glint to different parts of the cervix and maintain the region of interest glint free or to a large extent eliminate the glint completely Another method involves using multiple light sources directed at different angles towards an object see for example K T Schomacker T M Meese C Jiang C C Abele K Dickson S T Sum and R F Flewelling Novel optic
42. mage is formed by subtract ing the perpendicular component from the parallel component by taking a ratio of the parallel and perpendicular components or by using some combination of a ratio and difference of the parallel and perpendicular components U S Pat No 5 989 184 to Blair incorporated herein by reference discloses an apparatus for digital colposcopy and videography which comprises a digital imaging camera that is operably coupled to the optical path of the digital colpo scope by means ofa beam splitter so that a digital image of the cervico vaginal tissue can be captured The digital imaging camera and digital colposcope are mounted to one end of an articulating arm of the apparatus Digital processing means is operably connected to the digital imaging camera to create a digital image The digital processing means is housed in a stand of the assembly USS Pat No 6 277 067 to Blair incorporated herein by reference discloses a method and portable apparatus for the visual examination and grading of cervical epithelium by means of a hand held colposcopy assembly capable of pro ducing a digital image of the cervix The apparatus enables real time imaging and archiving of images of the entire cervix for the purpose of detecting cancerous and pre cancerous tissue and by virtue of computerized image processing sug gests an objective diagnosis of the cervical epithelium by means of a low cost portable hand held digital colposcope
43. ms such as described in S Nakappan S Y Park D Serachitopol R Price M Cardeno S Au N Mackinnin C MacAulay M Follen and B M Pikkula Methodology of real time quality control for the multispectral digital colposcope Gynecologic Oncology 107 S21 S222 2008 incorporated herein by ref erence In these systems the polarization filters are typically actuated by computer controlled rotating filter wheels or manually operated rotating filter holders either on the light source side or detection side or both Being able to remove or rotate the polarization filters allows for the acquisition of both cross polarized imagery without glint and regular imag ery with glint A drawback of using manually operated or computer controlled mechanical assemblies to switch or rotate the polarization filters is the inevitable wear and tear and ultimate failure of these units over time In addition mechanical switch or rotational devices will introduce a delay between the image viewing or capture of cross polarized and regular imagery During this delay significant movement of the colposcope and or the patient can occur This movement can make it extremely difficult to register align images and track diagnostically important features such as blood vessels of varying sizes This is especially true for a fully automated CAD system that does not rely on human direction or inter vention Another factor contributing to poor cervical imagery with
44. n and is adjustably spaced relative to the CCD detector The detector is coupled to a wireless transmitter mounted in the housing the trans mitter transmitting the output from the detector to a remotely located wireless receiver The wireless receiver is coupled to a computer which then processes the output from the detec tor The processed output is then displayed on a display The display may be remotely situated for remote expert diagnosis U S Pat No 6 766 184 to Utzinger et al incorporated herein by reference discloses methods and apparatus for generating multispectral images of tissue The multispectral images may be used as a diagnostic tool for conditions such as cervical cancer detection and diagnosis Primary radiation is produced with an illumination source The primary radiation is filtered to select a first wavelength and a first polarization Tissue is illuminated with the filtered primary radiation to generate secondary radiation which is filtered to select a second wavelength and a second polarization The filtered secondary radiation is collected with a detector and a plural ity of multispectral images of the tissue is generated accord ing to different combinations of first and second wavelengths and first and second polarizations with an analysis unit in operable relation with the detector Apparatus utilizing the invention include endoscopes and colposcopes U S Patent Application Publication No 2006 0141633 to Bal
45. nd at what magnification the images are captured by the cameras PP images will resemble standard colposcopic images and although XP images will be visually blurrier they will lack the glint present in the PP images A second preferred embodiment comprises two sets of LEDs and uses one camera at a single level of magnification US 8 289 378 B2 11 or continuous magnification by the use ofa zoom lens In this second preferred embodiment by rapidly switching between the two sets of LEDs after passing the unpolarized light through an IP the device will acquire two near simultaneous images with the same magnification of the same examined region one XP and one PP image Although the use of a zoom lens involves a mechanical movement of optical components with an associated time delay it would allow for the acquisi tion of XP and PP image pairs with different magnifications A third preferred embodiment is a simpler system which is similar to the first embodiment but includes only one set of LEDs and uses two cameras In this preferred embodiment unpolarized light from the single set of LEDs is polarized when it passes through an IP to create horizontally polarized light or light having a first polarization orientation to directly and uniformly illuminate a subject in a field of view The horizontally polarized light that interacts with the sub ject is reflected as total reflected light that includes horizon tally polarized glint and di
46. ntal orientation will be directed by the PBS to the first camera to create a second XP image The two cameras are preferably CCD charged coupled device or CMOS complimentary metal oxide semiconduc tor cameras that are co aligned aligned with each other but have different magnifications The first camera preferably has a first magnification a full view or a magnification that allows the entire subject of interest to be imaged and the second camera preferably has a second magnification a mag nified view or a magnification that allows for the viewing of the smallest diagnostically important features By rapidly switching between the two sets of LEDs by rapidly switching one set on and the other set off and vice versa the two cameras in the device will acquire four separate images of the same examined region two images at a first magnification and two images at a second magnification Of the two images at a first magnification one image will be parallel polarized and the other will be cross polarized The same applies to the two images at a second magnification one will be parallel polarized and the other will be cross polarized Rapidly switching between the two sets of LEDs by elec tronically turning their operating current on and off allows for near simultaneous acquisition of images that are co reg istered co aligned by the two cameras and controls whether the imaging system captures parallel or cross polarized images a
47. o be visualized at multiple magnifications thereby further enhancing the invention s diagnostic capabili ties To produce a brighter and more uniform illuminated surface with a denser light emission than typical fluorescent and incandescent light sources the light source in this embodiment preferably includes two sets of multiple light emitting diodes LEDs which are preferably turned on and off rapidly by electronically changing the operating current or voltage to directly and uniformly illuminate a field of view The light from the LEDs is preferably polarized through an illumination polarizer before reaching the field of view The present invention s use of LEDs offers several ben efits LEDs unlike fluorescent and incandescent lights are solid state components allowing for faster switching on and off so that switching between parallel polarized image acquisition and cross polarized image acquisition can be achieved more easily and quickly The invention preferably uses fixed illumination polarizers IP in front of the two sets of LEDs instead of mechanically moving polarizing filters Rapidly switching between the LEDs rapidly alternating each set of LEDs on and off also reduces the influence from patient movement between successive images allowing for better registration alignment between successive images and improving the possibility of detection of diagnostically important features An LED assembly is also less expensive
48. ssel patterns that cannot be easily seen by using regular white light Although the standard colposcopic exam and regular screening have led to dramatic decreases in the overall inci dence of cervical cancer new technologies can further enhance the sensitivity and specificity of currently accepted colposcopic practices Digital imaging is one such technol ogy that can revolutionize medical imaging and enables sophisticated computer programs to assist the physician with CAD Computer Aided Detection or Computer Aided Di agnosis The combination of digital imaging and CAD could have a direct impact on improving women s health and decrease the associated cost by automatically identifying CIN in real time with high sensitivity and specificity This would mean fewer false positive biopsies or ultimately elimination of biopsies A CAD system operating as an adjunct to colposcopy could minimize the high variability among colposcopists and enable consistent higher standards for accuracy A product realization where a CAD system is incorporated into a low cost device creating in effect a machine expert colposcopist would have the potential of increasing the availability and cost effectiveness of screening in developing countries Digital imaging provides a means for implementing a com puterized clinical data management system This data man agement system could provide management display and annotations of the acquired digital data as wel
49. to create polarized light in said field of view having a second polarization orientation and wherein said polarized polarizing unpolarized light from LEDs to produce polar ized light having a first polarization orientation light having said second polarization orientation is 45 illuminating a field of view containing tissue with said reflected by said tissue as second total reflected light polarized light having a first polarization orientation wherein said second polarization orientation is substan reflecting said polarized light off said tissue as total tially perpendicular to said first polarization orientation reflected light apolarizing element to receive said first total reflected light polarizing and splitting said total reflected light into a and said second total reflected light and split said total so parallel polarized output and a cross polarized output reflected light into a first parallel polarized output and a rapidly electronically switching between said parallel po first cross polarized output when said first set of LEDs is larized output and said cross polarized output to reduce illuminated and a second parallel polarized output and influence from patient movement between successive a second cross polarized output when said second set of images allowing for better registration between succes LEDs is illuminated 55 sive images a camera to receive one of said cross polarized outputs to collecting said rapidly electronica
50. tor and technicians and iii include comprehensive information with respect to each image data set about the state of the system when the images were acquired It also preferably contains a fully integrated user interface in which physical buttons are tied to the hardware and software platforms permitting the functionality of the device to be adapted if necessary to new functions A data management system with similar features is described in co pending commonly assigned U S patent application Ser No 11 184 046 entitled Uterine Cervical Cancer Computer Aided Diagnosis filed on Feb 3 2005 incorporated herein by reference The present invention is also preferably a self contained system meaning it is unnecessary to switch between a col poscope and a physically separate computer to review and annotate images and the system eliminates cable bundles that would otherwise be present between a colposcope and a com puter The presently preferred embodiment of the invention also discloses a process of creating polarized light illuminating a field of view with the polarized light reflecting the polarized light off a subject in the field of view splitting the reflected light into parallel polarized and cross polarized outputs pro ducing a parallel polarized image from the parallel polarized output and a cross polarized image from the cross polarized output and using the parallel polarized image and cross polarized image to enh
51. xel U S Patent Application Publication No 2005 004365 to Zelenchuk incorporated herein by reference discloses a sys tem and method for the in situ discrimination of healthy and diseased tissue A fiberoptic probe is employed to direct ultra violet illumination onto a tissue specimen and to collect the fluorescent response radiation The response radiation is observed at three selected wavelengths one of which corre sponds to an isosbestic point In one example the isosbestic point occurs at about 431 nm The intensities of the observed signals are normalized using the 431 nm intensity A score is determined using the ratios in a discriminant analysis The tissue under examination is resected or not based on the diagnosis of disease or health according to the outcome of the discriminant analysis DISCLOSURE OF THE INVENTION The present invention addresses the problem of glint inher ent in performing a standard colposcopic exam and addresses the limitations of using mechanical filter wheels or rotating filter assemblies the brightness of the light source the health aspects of exposure to UV and IR hazards and the extended start up time of most bright light sources by employing a non mechanical non moving fixed or stationary polariza tion assembly with an electronically switchable light source system based on high intensity light emitting diodes LEDs which do not to generate any UV or IR radiation 20 25 30 35 4
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