Patent Application
20080146898
The present invention is related generally to medical devices adapted for treatment, and more particularly to a medical device using a scanned beam assembly to treat and/or image body tissue.
U.S. Published Application 2005/0020926A1 discloses a scanning beam imager 102 which is reproduced in
The illumination sources disclosed in U.S. Patent Application Publication 2005/0020926A1 suffer from drawbacks that limit their utility in surgical practice. Blood vessels may be deliberately or accidentally cut or injured during surgical procedures. The resulting flow of blood often collects in a pool or film, which obscures the source of the blood, until the compromised vessel is clamped or ligated in order to prevent further flow. It would be an advantage for the surgeon to be able to see through the pool or film of blood to observe body tissue and/or to effect medical or surgical treatment.
Accordingly, there is a need for imagers using auxiliary illumination and detectors sensitive to wavelengths allowing visibility through blood, thereby increasing the quality of the image or view obtained during a particular surgical procedure.
One embodiment of the invention is a scanning beam assembly for use in medical applications, comprising a plurality of radiation emitters that emit radiation over different wavelength ranges, wherein at least one of the emitters emits radiation that is minimally absorbed by blood, a scanner including a reflector that receives radiation from the emitters and directs it onto a field-of-view, and at least one detector configured to receive the radiation scattered, reflected, or transmitted by the field-of-view and generate an electrical signal.
Another embodiment of the present invention is a method for viewing body tissue in the presence of blood comprising the steps of (a) providing a medical device including a plurality of radiation emitters that emit radiation over different wavelength ranges coupled into an optical fiber assembly having at least one signal inlet, at least one of the emitters operating in a wavelength range that is minimally absorbed by blood, a scanner including at least one reflector configured to direct the radiation from the emitters onto a field-of view, at least one detector configured to receive and detect the radiation scattered, reflected, or transmitted by the surrounding field-of-view, (b) generating a video image stream based on electrical signals generated by the detector(s), and (c) displaying a video image of the field-of-view to a user. The term “viewing” as used herein does not require the formation of an image. It includes procedures in which a tissue may be examined optically, electronically, or otherwise and treated accordingly.
The present invention has, without limitation, application in conventional endoscopic, laparoscopic, and open surgical instrumentation as well as application in robotic-assisted surgery.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects and advantages of the invention will be apparent from the description and the drawings, and from the claims.
Before explaining the present invention in detail, it should be noted that the invention is not limited in its application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. The illustrative embodiments of the invention may be implemented or incorporated in other embodiments, variations and modifications, and may be practiced or carried out in various ways. Furthermore, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the illustrative embodiments of the present invention for the convenience of the reader and are not for the purpose of limiting the invention.
Referring to
In one embodiment of the present invention, as shown in
Radiation source 16 may include multiple emitters such as, for instance, radiation emitting diodes (LED's), lasers, thermal sources, arc sources, fluorescent sources, gas discharge sources, or others. Radiation source 16 may be tunable using control unit 24. In some embodiments, radiation source 16 is capable of providing multiple types of radiation, for example, selected for imaging, therapy, diagnosis, or combinations thereof.
In one embodiment, radiation source 16 includes an auxiliary emitter 31 that is capable of generating a beam of radiation having a wavelength in the spectral window that is minimally absorbed by blood, as will be described in greater detail below. In another embodiment, auxiliary emitter 31 may generate a beam of radiation that is minimally absorbed by blood and function as a therapeutic beam. Beam combiner 32 may combine the radiation from auxiliary emitter 31 with the radiation from the multiple emitters 25, 27, 29 into a single beam. In another embodiment, the radiation from auxiliary emitter 31 is a separate beam.
Blood within the FOV interacts with incoming radiation from the radiation source 16, reflected radiation from the surfaces within the FOV, and any other radiation source present by absorbing, transmitting, reflecting, and scattering the radiation. For visible wavelengths, absorption by a blood film or blood pool reduces the amount of illumination reaching the underlying tissue(s) or surfaces of the body and further reduces the amount of reflected radiation reaching the detector. Auxiliary emitter 31 emits radiation in the spectral windows where the radiation is minimally absorbed by blood at an intensity such that upon detection by photodetector(s) 20 and processing by image processor 22 enhances the quality of the image obtained. Since the transmittance of radiation in the spectral window is not high, in one embodiment, the emitter 31 may operate at an intensity that is at least about ten times the intensity of the visible radiation emitters. In another embodiment, the emitter 31 may operate at an intensity that is at least about 50 times the intensity of the visible radiation emitters.
Based on the oxygenation level of the blood pool, the clinician may select from a plurality of the spectral windows at which to operate the emitter 31. Compared to human medicine, veterinary medicine applications may require a different complement of wavelength choices and selection methodology. The clinician should select the spectral window that minimizes absorption of the radiation by the blood. Control unit 24 enables the clinician to select the spectral window that is most appropriate for the particular circumstances. In one embodiment, control unit 24 switches between various emitter sources that are set at specific wavelengths. In another embodiment, control unit 24 filters the wavelengths emitted from an emitter source to only allow the selected spectral window of wavelengths or even a single wavelength to be received by the scanner.
Examples are provided below in which the particular subject's blood is either human or porcine, and the blood is either oxygenated or deoxygenated. Many other spectral windows are possible for other animal related blood applications. For example, oxygenated porcine blood exhibits minimal absorption of radiation between spectral windows at about 650-750 nm, about 1050-1150 nm, and about 1200-1300 nm, and deoxygenated porcine blood exhibits minimal absorption of radiation between spectral windows at about 650-750 nm and about 1250-1300 nm. As another example, oxygenated human blood exhibits minimal absorption of radiation between spectral window at about 650-750 nm and about 1050-1150 nm. Deoxygenated human blood exhibits minimal absorption of radiation between spectral window at about 700-750 nm and about 1050-1150 nm.
Additionally, U.S. Pat. No. 6,178,346 discloses that visualization through opaque-body-fluid environments, such as blood, is improved by using wavelengths in the infrared. The patent discloses that low scattering by the suspended cells and low absorption by water and hemoglobin can be obtained in the wavelength regions: 1400-1800 nm, 2100-2400 nm, 3700-4300 nm, 4600-5400 nm, and 7000-14000 nm. In still another embodiment, the spectral window includes radiation in the range of about 1500-1800 nm. It is noted that in describing the auxiliary emitter with respect to the wavelength range, it is only necessary that the emitter emit radiation at one or more wavelengths within the ranges as opposed to the entire range. The radiation emitter 31 may be an illumination source, that emits over a wavelength range, including one or more wavelengths in the ranges of 650-750 nm, 1050-1300 nm, 1400-1800 nm, and 2100-2400 nm. High power radiation sources that emit in these ranges are commercially available.
Furthermore, at least one or more of the photodetectors 20 must absorb effectively within the aforesaid ranges. Photodetectors that are sensitive to radiation in the spectral window are commercially available. Additionally, the optical fibers employed in the scanners must be able to transmit the radiation and particularly the auxiliary radiation. One type of optical fiber that is useful for transmitting infrared radiation is a so-called holey optical fiber.
In one embodiment, the image acquired in the auxiliary radiation (long wavelength) detector channel may be overlaid on the full-color image obtained from the image signal acquired from the visible radiation detector channels. In another embodiment, the image acquired from the auxiliary radiation detector channel may be overlaid in a false color, for example, one not often seen in normal anatomy. In summary, the image obtained from the auxiliary signal may replace the full color image, or be added in so as to preserve anatomical detail.
In one aspect of the present invention, a method for viewing body tissue in the presence of blood includes the steps of: a) providing a medical device including a plurality of radiation emitters that emit radiation over different wavelength ranges coupled into an optical fiber assembly having at least one signal inlet, at least one of the emitters operating in a wavelength range that is minimally absorbed by blood, a scanner including at least one reflector configured to direct the radiation from the emitters onto a field-of view, and at least one detector configured to receive and detect the radiation scattered, reflected, or transmitted by the surrounding field-of-view; b) generating a video image stream based on electrical signals generated by the detector(s); and c) displaying a video image of the field-of-view to a user.
In accordance with other embodiments of the invention, an auxiliary emitter 31 emitting radiation minimally absorbed by blood and, more particularly, within one or more of the wavelength ranges disclosed herein can be used in conjunction with one or more of the scanning beam imagers described in U.S. Pat. No. 7,071,594 and U.S. Published Application 2005/0116038, both assigned to Microvision, Inc.
The foregoing description of several embodiments and expressions of the invention have been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in the above teaching. For example, as would be apparent to those skilled in the art, the disclosures herein of the medical device for imaging have equal application in robotic assisted surgery taking into account the obvious modifications of such systems and components to be compatible with such a robotic system.
