Surgery – Endoscope – Having imaging and illumination means
Reexamination Certificate
2001-08-21
2003-10-28
Mulcahy, John (Department: 3739)
Surgery
Endoscope
Having imaging and illumination means
C600S178000, C600S181000
Reexamination Certificate
active
06638215
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video endoscope system that photographs images of body cavities using autofluorescence from living tissue to generate image data which is to be used to determine whether the tissue is normal or abnormal. The present disclosure relates to subject matter contained in Japanese Patent Application No. 2000-256168 (filed on Aug. 25, 2000) which is expressly incorporated herein by reference in its entirety.
2. Description of the Related Art
Recently, video endoscope system capable of observing fluorescence (autofluorescence) emitted from living tissue irradiated with a predetermined wavelength of excitation light are used. These video endoscope devices comprise a light source devices for emitting both visible light and excitation light that excites living tissue to cause autofluorescence. This excitation light is typically ultraviolet light. The living tissue irradiated with this excitation light emits autofluorescence. The intensity of the fluorescence generated by healthy tissue is stronger than that generated by unhealthy tissue. A video endoscope system of this kind irradiates living tissue with excitation light emitted from a light source device, creates a fluorescent image based on the intensity distribution of autofluorescence emitted from the living tissue to be displayed on a monitor. Note that in this fluorescence image, normal tissue appears bright, while diseased tissue appears dark. An operator observes the fluorescence image and determines portions darker than other portions in the fluorescence image as diseased tissue. However, the dark portions in a fluorescence image do not always indicate diseased tissue. For example, undulant shape of the tissue itself and a forceps projecting from the distal end of the endoscope forms shadows in the body cavity, which are indicated as dark portions in the fluorescent image. Thus, shaded portions are not easily distinguished from diseased portions.
Therefore, a video endoscope system which generates diagnostic images in which diseased areas are distinguished from shaded portions is proposed. A light source device of this video endoscope system sequentially and repeatedly emits green light, blue light, red light, a reference light that is visible light of a predetermined wavelength, and excitation light. The emitted light is guided into the body cavity of a patient through a light guide installed in the video endoscope to irradiate living tissue. An objective optical system installed in the video endoscope forms images of the object from the green light, the blue light, and the red light, respectively, during the period when the light source device emits the green light, during the period when it emits the blue light, and during the period when it emits the red lights. The images are converted into image signals by a CCD installed in the video endoscope. The image signals are synthesized into a color image by a processor of the video endoscope system.
On the other hand, the objective optical system forms a reference image of the object from the reference light during the period in which the light source device emits the reference light. Also, the objective optical system forms an autofluorescence image of living tissue during the period in which the light source device emits the excitation light. These reference and autofluorescence images are converted into image signals by the CCD, and the image signals are input to the processor. The process or subtracts the image signal obtained from the reference light from the image signal obtained from the autofluorescence to extract only portions from which only weak fluorescence is generated due to abnormalities. Furthermore, the processor sets these portions extracted from the fluorescence image signal to a predetermined color and superposes them on the color image to create a diagnostic image. In this diagnostic image, the operator can distinguish diseased portions from the shaded portions and easily recognize the locations of the diseased areas.
The light source device for this video endoscope system will be described in further detail, referring to FIG.
8
. The light source device has a first light source
81
for emitting white light and a second light source
82
for emitting light containing the components of the spectra of the excitation light and reference light. A first wheel
83
, a first shutter
84
, a prism
85
, a diaphragm
86
, and a condenser lens C are arranged along the optical path of white light emitted from the first light source
81
, in order. As shown in
FIG. 9A
, the first wheel
83
is a disk, with three openings formed along its circumference. These openings are fitted with a green filter
83
G, a blue filter
83
B, and a red filter
83
R to transmit green light, blue light, and red light, respectively. The first wheel
83
is joined to a motor (not shown) and driven to rotate by this motor. The first wheel
83
is disposed at a location where the filters
83
G,
83
B, and
83
R are sequentially inserted into the optical path of the white light emitted from the first light source
81
, with its rotation. The white light emitted from the first light source
81
is sequentially converted into green light, blue light, and red light by the filters
83
G,
83
B, and
83
R of the first wheel
83
. The converted light advances to the first shutter
84
. This shutter
84
can block incident light or allow it to pass therethrough. The light which passed through the first shutter
84
is then transmitted through the first prism
85
and enters the diaphragm
86
which adjusts amount of the light. The light is then converged by the condenser lens C on the proximal end of the light guide
87
.
A second prism
88
is disposed on an optical path of light emitted from the second light source
82
. The light emitted from the second light source
82
is split into transmitted light and reflected light by the second prism
88
. An excitation light filter
89
, a second wheel
90
, a third prism
91
, and a second shutter
92
are arranged along the optical path of the light transmitted through the second prism
88
, in order. The light transmitted through the second prism
88
then enters the excitation light filter
89
, which extracts and transmits only those components corresponding to the excitation light from the incident light. The transmitted excitation light then enters the second wheel
90
. As shown in
FIG. 9B
, the second wheel
90
is a disk, with one opening formed along its circumference. This opening is fitted with a transparent member to transmit the excitation light. The second wheel
90
is joined to a motor (not shown) and driven to rotate by this motor. The second wheel
90
is disposed at a location where the opening is periodically inserted into the optical path of the excitation light. The excitation light is then transmitted through the third prism
91
and advances to the second shutter
92
. The second shutter
92
can block the incident light or allow it to pass therethrough. The light which passed through the second shutter
92
is then reflected by the first prism
85
, and thereafter travels along the same optical path as the green light, the blue light and the red light as described above, and finally enters the light guide
87
.
A first mirror
93
, a reference light filter
94
, a third wheel
95
, and a second mirror
96
are arranged along the optical path of the light reflected by the second prism
88
, in order. The light reflected by the second prism
88
is further reflected by the mirror
93
, then enters the reference light filter
94
, which extracts and transmits only the components corresponding to the reference light from the incident light. The transmitted reference light then enters the third wheel
95
. As shown in
FIG. 9C
, the third wheel
95
is a disk, with one opening formed along its circumference. This opening is fitted with a transparent member to transmit the reference light. The third wheel
95
is connected to a motor (not shown)
Greenblum & Bernstein P.L.C.
Mulcahy John
Pentax Corporation
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