Patent Abstract:
An apparatus and method for creating a three dimensional imaging system is disclosed. There is a first source of laser light and a second source of laser light having a wavelength different from the wavelength of the laser light of the first source. The laser light from the first and second sources are combined, and the combined laser light is transmitted to a scanner. The scanner further transmits the combined light to a surface to be imaged.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 11/823,862, now issued as U.S. Pat. No. 7,983,738, which claims priority on U.S. Provisional Patent Application Ser. No. 60/817,623 filed on Jun. 29, 2006, the disclosures of which are incorporated herein by reference. This application is also a continuation in part of U.S. application Ser. No. 11/478,322, also filed on Jun. 29, 2006, which claims priority on U.S. Provisional Patent Application Ser. No. 60/757,704, entitled “Micro Vein Enhancer,” filed on Jan. 10, 2006, which are also incorporated by reference herein 
    
    
     SUMMARY OF THE INVENTION 
     A laser based imaging system that can image veins, arteries, or other organs containing blood, and can generate three dimensional images representative thereof. 
     BACKGROUND OF THE INVENTION 
     It is known in the art to use an apparatus to enhance the visual appearance of the veins and arteries in a patient to facilitate insertion of needles into those veins and arteries as well as other medical practices that require the identification of vein and artery locations. Such a system is described in U.S. Pat. Nos. 5,969,754 and 6,556,858 incorporated herein by reference as well as publication entitled “The Clinical Evaluation of Vein Contrast Enhancement”. Luminetx is currently marketing such a device under the name “Veinviewer Imaging System” and information related thereto is available on their website, which is incorporated herein by reference. 
     The Luminetx Vein Contrast Enhancer (hereinafter referred to as LVCE) utilizes a light source for flooding the region to be enhanced with near infrared light generated by an array of LEDs. A CCD imager is then used to capture an image of the infrared light reflected off the patient. The resulting captured image is then projected by a visible light projector onto the patient in a position closely aligned with the image capture system. The light source for flooding the region to be enhanced does not deeply penetrate into the patient, and therefore, only the veins on the surface of the patient are imaged. Further, the image representative of the veins which is rendered onto the patient is two dimensional and does not provide any depth information. Still further, there is no method using such technology to display blood flowing at a given depth in the patient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of the optical apparatus for the laser based vein enhancer of the present invention. 
         FIG. 2  is a control block diagram of the controlling elements of the optical apparatus of  FIG. 1 . 
         FIG. 3A  is a side cutaway view of a patient&#39;s arm. illustrating. the veins within the patient&#39;s arm. 
         FIG. 3B  is a top view of the veins in the arm of the patient in  FIG. 3A . 
         FIG. 3C  is a side view of the veins in the arm of the patient in  FIG. 3A . 
         FIG. 4A  is a side view of the veins in the arm of the patient in  FIG. 3A , showing the scan depth lines from N=1 through N=17. 
         FIG. 4B  shows 17 images for N=1 through N=17 of the arm of the patient in  FIG. 3A  that are stored in the image memory of laser based vein enhancer of the present invention. 
         FIG. 5  is a flow chart illustrating an embodiment of the image formatter of the optical apparatus of  FIG. 2 . 
         FIG. 6  is a top view of the veins in the arm of the patient in  FIG. 3A . utilizing different patterns to differentiate between the various different veins and arteries.  FIG. 7  is a flow chart of another embodiment of the image formatter of the optical apparatus of  FIG. 2 . 
         FIG. 8  is a flow chart of a third embodiment of the image formatter of the optical apparatus of  FIG. 2 . 
         FIG. 9  shows a top front perspective view of an embodiment of the image formatter of the optical apparatus of  FIG. 2 . 
         FIG. 10  shows the projection plane of the laser based vein enhancer of the present invention on a cross section of a patient&#39;s arm. 
         FIG. 11  is an illustration of how an embodiment of the laser based vein enhancer of the present invention accurately projects the correct vein size regardless of the depth of the veins within the patient&#39;s arm. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preliminary application 60/757,704, incorporated herein by reference, described a miniature laser based system for imaging a patient&#39;s veins and arteries and then rendering them onto the surface of the patient&#39;s skin. Tests of such a system has shown that the laser based imaging system can penetrate and image very deeply into the patients body, and in some cases, such as the hand or arm, can image entirely through the hand or arm. Further, it has been found that the depth of penetration of the imaging is a function of the amount of laser power applied. Using these principals, a three dimensional imaging system is now described. 
       FIG. 1 . shows the optical apparatus for a laser based vein enhancer. A single colored laser  180 , for example a 630 nm semiconductor red laser, is projected into combiner  181 . A semiconductor laser  183  is also projected into the combiner  181 . Laser  183  may have a wavelength from 700 nm to 1000 nm, with a preferred wavelength of 740 nm. 
     An illustrative example of a semiconductor 740 nm laser is Sacher Lasertechnik&#39;s Fabry Perot Diode Laser 740 nm, 10 mw, model number FP-0740-10. The combiner  181  outputs a combined laser beam  184  which is the combination of the 630 nm red and the 740 nm laser beams. Combiners for combining two lasers of different frequencies are well known in the art and will not be further described herein. The combined laser beam  184  is positioned to hit off mirror  172  and then to hit the MEMS scanner  173 . The MEMS scanner moves in a raster pattern thereby causing the combined laser beam to move along optical path  5  forming a raster pattern at the field of view  4 . A photodetector  182  which is responsive to the 740 nm wavelength is provided and receives 740 nm light reflected off objects in the field of view. The photodetector  182  outputs an analog signal representing the amount of 740 nm light received. An illustrative example of a photodetector is Roithner Lasertechnik&#39;s model number EPD-740-1. 
       FIG. 2  shows a control block diagram for controlling the elements in  FIG. 1  to form a three dimensional imaging system. An electronic block  192  for driving the MEMS driver and for sensing the position of the raster scanner is provided. This block  192  generates the signals required to drive the MEMS scanner  173  in a raster pattern, and also determines the exact instantaneous location of the MEMS scanner and communicates this information to an image memory array  191 A- 191 N. This electronic block  192  also generates output signals indicating the frame count and communicates such signals to image memory array  191 A- 191 N, image formatter  300 , image memory two  196 , and laser intensity block  301 . 
     Assuming the frame rate is sixty frames per second, the frame count will cycle from one through sixty. The operation is as follows. The MEMS scanner  173  is driven in a raster pattern. The first full frame after achieving a stable raster pattern will be identified as frame one by the frame counter. Thereafter each subsequent frame will increase the frame counter by one, up to sixty, and thereafter the frame counter will reset to one and then start the cycle again. Laser intensity block  301  drives the laser drivers  195  at a select one of sixty levels depending upon the current frame counter level. More particularly, the laser intensity block  301  drives the laser drivers  195  in such a manner that the power output from the 740 nm laser  183  linearly increases in sixty steps as the frame counter increments from one to sixty. During the first sixty frames of operation the laser drive  194  for the 630 nm laser  180  is turned off. The light from the 740 nm  183  is reflected off the patient and absorbed by the blood in the veins in a patient&#39;s body and the reflected light is sensed and converted into an analog signal by 740 nm photo detector  182 . The analog signal is then passed through an A/C converter  190  which outputs a digital representation to image memory  191 A- 191 N, wherein in this example A=1 and N=60. Image memory  191 A- 191 N receives instantaneous position information from the electronic block  192 , and based upon such information, the digital representation for each pixel is stored in a memory location corresponding to a particular pixel. This is repeated for each pixel within a frame. In this manner, each frame is stored in an associated image memory. Upon completion of the first sixty frames, the image memory  191 A- 191 N contains sixty images of the veins within the field of view of the 740 nm laser  183 , wherein each sequential image memory contains an image which has been obtained with increased laser intensity. After the completion of the sixtieth frame, the image memory is forwarded to an image formatter  300 , which in turn forms an image which is transferred to image memory two  196 . During each of the next sixty frames of the cycle, the data in the image memory two  196  is read out as a function of the instantaneous position information provided by the electronic block  192  and provided to a D/A converter  193  which outputs an analog signal to laser drive  194  which drives the 630 nm laser  180 . In this manner, the image that was stored in image memory two  196  is projected by the 630 nm laser  180  onto the patient. In this manner, the veins that are in the field of view become visible to the practitioner. 
     While in the above embodiment, the frame count (number of slices of images taken) was sixty, the frame count could be more or less than sixty. Also, the laser intensity  301  was indicated to go up linearly. It is also possible to have a look-up table or algorithm which provides for non-linear step-ups in power. To simplify the discussion, the power changes have been described in a “step-up” fashion. The order in which the various steps are taken are unimportant, it is the capture of the vein signal at various intensities is what is important to the process. 
     The operation of image formatter  300  will now be described in greater detail. To simplify the Figs. shown, a maximum frame count of 17 (N=17) is illustrated as opposed to the frame rate of 60 (N=60) previously described. Accordingly, for the purpose of the illustrations the laser will cycle through 17 frames at 17 different increasing power levels. Referring to  FIG. 3A , a three dimension illustration of a patient&#39;s arm  309  is shown. The arm has a top vein  310  which is closest to the top surface and bottom vein  312  which is the deepest as viewed from the top surface and middle vein  311  which is between the two.  FIG. 3B  shows a top view  308  of the veins  310 ,  311  and  312  as viewed from the top of the arm if the arm was transparent and the veins were not.  FIG. 3C  shows a side view  307  of the veins  310 ,  311  and  312  as viewed from the side of the arm (assuming again for the moment the arm is transparent and the veins are not). 
     The laser based vein enhancer of  FIG. 1  and  FIG. 2  is positioned so that the field of view corresponds with the top view  308  of the patient&#39;s arm  309  shown in  FIG. 3 .  FIG. 4A  again shows the side view  307  but also includes along the right edge scan depth lines  314  N=1 through N=17. These scan depth lines  314  indicate how deeply the laser light penetrates into the arm at each respective laser intensity level N=1 through N=17.  FIG. 4B  shows 17 images N=1 through N=17 that are stored in image memory  191 A- 191 N. Referring to the image memory associated with frame one (N=1), the intensity of the laser only penetrates the patient arm to the depth shown by the N=1 scan depth line  314 . 
     Since this depth does not reach vein  310 ,  311  or  312  as shown in  FIG. 4A , the image stored for the first frame N=1 is blank. The same applies to the second frame N=2. The third frame N=3 reaches partly into vein  310  and accordingly the image stored in image memory associated with the third frame (where N=3) begins to faintly show vein  310 . Frames  4 ,  5  and  6  each penetrate successively deeper into vein  310  and therefore the image of vein  310  gets successively darker in the image memory  191 A- 191 N associated with frames  4 ,  5  and  6  (N=3, 4 and 5). Similarly, starting with frame  7  (N=7), the middle vein  311  begins to appear and then starting with frame  11  (N=11) the deepest vein  312  begins to appear. By frame  14  the laser light penetrates all the way through veins  310 ,  311 , and  312  and therefore the images for frames  14  through frame  17  are approximately the same and show all the veins. 
     If the image for frame  17  (N=17) were to be projected onto the patients arm, there would be no way for the practitioner to determine the relative depths of veins  310 ,  311  or  312 . Accordingly the image needs to be reformatted so as to provide additional information to the practitioner before projecting on the patients arm. 
     Referring to  FIG. 5 , an illustrative embodiment of the image formatter  300  of  FIG. 2  is flow-charted. The frame counter N is set at 0 in step  2  and all previously stored vein/artery images are cleared. In step  3  the counter N is increased by one. In step  4  the frame counter is tested to see if all 17 frames are completed. Accordingly, step  5  will be reached for each of the 17 successive images (N=1 through N=17). In step  5  the image N is recalled from the appropriate image memory  191 A- 191 N. In step  6  all previously stored vein/artery pattern are subtracted. During the first frame N=1 there will be no previously stored vein/artery pattern to be subtracted since they were cleared at step  2 . At step  7 , image processing is performed to detect whether a vein or artery pattern is found. Since it is know that veins and arteries are tube shaped and have a length much greater than their diameter, relative straightforward computer processing can be used to identify such a pattern. If a new pattern is detected at step  8  the new vein/artery pattern is stored at step  9  and the program returns to step  3 . If there is no new pattern detected in step  8  the program returns to step  3 . 
     Now applying step  1  through step  8  to the images shown in  FIG. 4B , assuming that image N=3 represents the first time step  7  detects a vein  310 , the image of the vein  310  is stored at step  8 . Thereafter, in each subsequent image processed, the image of vein  310  is removed from the image at step  6 . Then assuming when the N=7 the second vein  311  is detected in step  9 , the image of vein  311  is stored and accordingly removed the next time the program reaches step  6 . Finally when the N=11 the deepest vein  312  is detected in step  9 , the image of vein  312  is stored and accordingly removed the next time the program reaches step  6 . After completing the last frame  17 , the program moves to Step  9  wherein each stored vein/artery pattern is replaced with a unique pattern. For example, the pattern of vein  310  can be replaced with a diagonally striped pattern, the pattern of vein  311  can be replaced by a checked pattern, and the pattern of vein  312  can be replaced with a light grey pattern. At step  10  each of the now unique patterns for each of the stored vein/artery patterns are layered on top of each other, with the first found pattern falling on the top, the second pattern in the middle and the third pattern on the bottom. In step  11 , the image of step  10  is transferred to image memory two  196  (See  FIG. 2 ). The image of step  10  is then projected by the visible laser onto the patients arm. 
       FIG. 6  shows the resulting image  320  projected onto the patients arm. As can be seen, vein  310  is represented by the diagonally striped pattern, vein  311  represented by the checked pattern, and vein  312  by a light grey pattern. It is clear to the practitioner that vein  310  is positioned above veins  311  and  312  since the diagonally striped pattern at the intersection points of the respective veins. Similarly it is clear that vein  311  is positioned above vein  312  since the checked pattern appears at the intersection point of veins  311  and  312 . 
     In  FIG. 6 , diagonal striped patterns, checked pattern, and a light grey pattern were utilized for differentiating between the various different veins/arteries, however, the invention is not limited thereto. Varying patterns, such as dotted lines having different dot-space characteristics could have been utilized to represent veins at different depths. Alternatively, solid images having different intensities could have been utilized, wherein, for example, those veins closer to the surface are represented by dark projections and deeper veins by lighter projections. Still further, the red laser  180  could be replaced by multiple color lasers, for example red, green and blue, all arranged so that their projections are aligned coaxially. By mixing the amount of each laser, color images can be projected. Accordingly, each different depth vein can be represented by a different color. 
     A further embodiment is shown with reference to  FIG. 7 . In this embodiment, the capturing of the vein/artery image is the same as shown previously with reference to  FIG. 2  and the resulting image gets stored in image memory  191 A- 191 N. However, in this embodiment, the image is not transmitted back onto the patient, but instead is transfer to a computer  325  and is then displayed on a three dimension (3D) display  326 . More specifically, three dimensional computer software is known in the art, such a CAD (computer aid design) software or medical imaging software, for manipulating and outputting 3D images. One example of such CAD software is SolidWorks. An example of medical imaging software is an Advanced 3D Visualization and Volume Modeling software from Amira. See Real Technologies provides a stereo 3D display (Model C-s Display) which receives image information over a DVI connection from a graphics card of a Windows based computer and allows the user to view such 3D image without necessitating special glasses. Such Windows based computer must be fitted with a special graphics card, such as NVidea Open GL Video card, to enable the driving of the display. 
     Utilizing the computer  325  and 3D display  326 , the practitioner can view the veins in 3 dimensions. The 3 dimensional images can be rotated by the CAD software, and cross-section slices of the 3 dimensional images can be performed. Still further, it is possible to utilize a 2 dimensional display with CAD software converting the 3D image into meaningful 2D displays. 
       FIG. 8  shows a still further embodiment wherein the visible laser projection onto the patient of  FIG. 2  is combined with the 3D display  326  described with reference to  FIG. 7 . In this case, the image is projected onto the patient by the 630 nm laser  180  while concurrently being displayed in 3D on screen  326 . In this manner the practitioner can find the exact positioning of the veins as projected on the patient and can also view a 3D representation of the veins/arteries under the surface. 
       FIG. 9  shows an embodiment similar to that shown in FIG. 15A of preliminary application No. 60/757,704. 
     In this embodiment the Miniature Vein Enhancer (MVE)  150  includes a small display  325 ; having attached thereto an attachment piece  154  and a Miniature Projection Head (MPH)  2 . Although the attachment is shown at a right angle to the stem extending vertically from the vial, the stem can be at an angle to the vial and the display angle can vary, as well. A needle protector  156 , connects to a vial holder  7 . The attachment piece  154  receives the top of the needle protector and temporarily locks the MVE to the needle protector  156  which in turn attaches to the vial holder  7 . The MPH  2  is attached to the small display  151  and is oriented so that the optical path  5  is such that the field of view  4  covers the point of the needle  14 . The MPH  2  outputs the image of the veins  11  onto the field of view  4  on the patient (not shown). The MPH  2  also provides the image signal to the display  151  to be viewed on the display  151 . The image signal includes both the veins and the needle  14 . The display  151  includes image processing capabilities that detects the position of the tip of the needle and displays a predetermined number of pixels of the image around the tip of the needle on the display. In  FIG. 14C , both the image of the needle  153  and the image of the vein  152  are shown. 
     The unit of  FIG. 9  is driven by the electronics (not shown) describe previously in  FIG. 8 , wherein the computer  325 , including the graphics card logic and 3D software, are miniaturized and housed in the MVE  150  and wherein the display is a small 3D display  326  attached to the MVE  150 . Accordingly, when this device is used, the practioner can view the projected image on patient, as well as the three dimensional image on the 3D display  326 . 
     With reference to  FIG. 10 , a correction methodology is now described. The projection/imaging optical cone  445  of the MVE unit originates at the mirror of the MVE and diverges from there. The projection angle, for example, could be 60 degrees. A cross section of a patient&#39;s arm  446  is shown with a cross section of a first vein  443  shown at a first imaging plane  441  and a cross section of a second vein  444  shown at a second imaging plane  441 . A projection plane  440  is also shown, which is approximately on the top surface of the arm  446  of the patient and represents where the image is displayed on the patient. In this example, the first imaging plane  441  is half way between the projection plane  440  and the second imaging plane  442 . Due to the projection angle, the second imaging plane  442  is wider than the first imaging plane  441  which in turn is wider than the projection plane  440 . In this example, the first vein and the second vein are each the same size. The first vein  443  as viewed at the first imaging plane  441  is one quarter the width of the first image plane  441 . The second vein  444  as viewed at the second imaging plane  442  is one sixth the width of the second image plane  442 . Accordingly when the images of the first and second veins are projected on the arm  446  on projection plane  440 , the first vein  443  will appear to be one quarter the width of the projection plane  440 , and the second vein  444  will appear to be one sixth the width of the projection plane  440 . It should be noted that neither the projected image of the first vein  443  nor the projected image of the second vein  444  is accurately representative of the actual vein size. 
     In accordance with the present invention, a scaling process can be performed prior to transmitting the image of the veins onto the projection image plane  440 . As previously described, the laser power of the 740 nm laser can be sequentially increased for each frame. A depth table correlating the depth of penetration of the 740 nm laser as a function of laser power can be pre-stored in memory. This depth information can then be used to correct the actual image size of the veins  443  and  444  prior to projecting their images onto projection plane  440 . The correction algorithm can be straight forward trigonometry and therefore is not described herein. 
       FIG. 11  describes an embodiment which accurately projects the correct vein size regardless of the depth of the veins  443  and  444  within the patients arm. The optical path diverges at an angle  447  and hits a parabolic minor  448  which is arranged to have a shape so that the optical beam  449  exiting off the mirror  448  is parallel and does not diverge. In this manner, the image of the veins.  443  and  444  are both the same size, and when they are projected onto projection plane  440 , the size of the vein images exactly matches that of the actual veins. As an alternative embodiment, a lens could be used instead of a parabolic mirror  448  for converting the diverging optical path to a parallel path. 
     As yet a further embodiment, it has been determined that increasing the wavelength of the laser light emitted from the laser  183  increases the depth of penetration into the flesh of the patient. This effect can be used to construct three dimensional images by increasing the wavelength of laser light emitted on sequential frames, thereby allowing the system to determine the depth of the veins (this is similar to the previous embodiment where the laser intensity was increased to obtain greater penetrations). 
     It should be noted that all embodiments herein have been described with a 740 nm laser  183  for imaging the veins/arteries. However, a broader range of wavelengths (700 nm to 1000 nm) could be utilized. Similarly, in the event a broader range of wavelengths are emitted by laser  183 , the 740 nm photo detector  182  could be changed to a different wavelength to receive the associated wavelength (700 nm-1000 nm). Still further, the 630 nm (red) laser  180  has been utilized for displaying the image on a patient. The 630 nm (red) laser  180  could be replaced with any visible laser (generally in the range of 400 nm-700 nm). Still further, the single (red) laser  180  could be replaced with multiple lasers configured so that they project coaxially. For example, if red, green and blue lasers are utilized, full color images can be rendered. 
     It also should be noted that often description is made of identifying vein, and in some cases veins and/or arteries. The invention is not limited thereto. Any portion of the body containing blood would be appropriately imaged by the devices of this invention.

Technology Classification (CPC): 0