Information
-
Patent Grant
-
6496719
-
Patent Number
6,496,719
-
Date Filed
Friday, December 22, 200023 years ago
-
Date Issued
Tuesday, December 17, 200221 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 600 476
- 600 477
- 600 478
- 600 160
- 250 4581
- 356 317
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International Classifications
-
Abstract
A complementary color filter transmits only fluorescence components of fluorescence having been produced from a measuring site exposed to excitation light, which fluorescence components have wavelengths falling within a wavelength region acting as a complementary color with respect to a desired wavelength region. A complementary color signal intensity detector detects a signal intensity of the fluorescence components having passed through the complementary color filter. An entire signal intensity detector detects a signal intensity of fluorescence components, which have wavelengths falling within an entire measurement wavelength region. A signal intensity of fluorescence components, which have wavelengths falling within the desired wavelength region, is calculated from the signal intensities detected by the complementary color signal intensity detector and the entire signal intensity detector. Image information in accordance with the thus calculated signal intensity is displayed.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for displaying a fluorescence image, wherein a fluorescence image in accordance with characteristics of fluorescence, which is produced from a measuring site in a living body when the measuring site is exposed to excitation light, is displayed.
2. Description of the Related Art
There have heretofore been proposed apparatuses for displaying a fluorescence image, wherein location and an infiltration range of diseased tissues are displayed as an image by the utilization of characteristics such that, in cases where excitation light having wavelengths falling within an excitation wavelength range for an intrinsic dye in a living body is irradiated to the living body, a pattern of a fluorescence spectrum of fluorescence produced by the intrinsic dye in the living body varies for normal tissues and diseased tissues.
FIG. 12
shows typical fluorescence spectra of the fluorescence produced from normal tissues and the fluorescence produced from diseased tissues, which fluorescence spectra have been measured by the inventors. It is assumed that the thus produced fluorescence results from superposition of the fluorescence produced by various kinds of intrinsic dyes in the living body, such as FAD, collagen, fibronectin, and porphyrin.
With the proposed apparatuses for displaying a fluorescence image, basically, fluorescence components of the fluorescence, which has been produced from a measuring site in the living body when the excitation light is irradiated to the measuring site, are detected via each of a plurality of band-pass filters, and the fluorescence components having wavelengths falling within desired wavelength regions are thereby selected. Also, signal intensities of the thus selected fluorescence components are detected. Thereafter, information in accordance with the detected signal intensities is displayed as a fluorescence image on a monitor, or the like. Therefore, a person who sees the displayed information is capable of recognizing the state of the diseased tissues. In many cases, the apparatuses for displaying a fluorescence image take on the form built in endoscopes, which are inserted into the body cavities, colposcopes, operating microscopes, or the like.
Ordinarily, as a combination of wavelength regions of the fluorescence components to be selected from the fluorescence, a combination of a red wavelength region and a blue wavelength region, at which the difference between the pattern of the fluorescence spectrum obtained from normal tissues and the pattern of the fluorescence spectrum obtained from diseased tissues occurs markedly, or a combination of an entire measurement wavelength region, from which a large amount of light is capable of being obtained, and the blue wavelength region, or the like, has heretofore been selected. For example, in cases where the combination of the red wavelength region and the blue wavelength region is to be selected, a mosaic filter constituted of a combination of band-pass filters, which transmit only the fluorescence components having wavelengths falling within the red wavelength region, and band-pass filters, which transmit only the fluorescence components having wavelengths falling within the blue wavelength region, has heretofore been located at a front surface of an image sensor. In this manner, the fluorescence components having wavelengths falling within the red wavelength region and the fluorescence components having wavelengths falling within the blue wavelength region have heretofore been detected. In cases where the combination of the entire measurement wavelength region and the blue wavelength region is to be selected, a mosaic filter constituted of a combination of blank areas, which transmit the fluorescence components having wavelengths falling within the entire measurement wavelength region, and the band-pass filters, which transmit only the fluorescence components having wavelengths falling within the blue wavelength region, has heretofore been utilized.
However, the fluorescence, which is produced from the living body tissues when the living body tissues are exposed to the excitation light, is weak. With the conventional apparatuses for displaying a fluorescence image described above, the fluorescence components having wavelengths falling within a desired wavelength region are selected from the weak fluorescence by use of the band-pass filter, which transmits only the fluorescence components having wavelengths falling within a primary color wavelength region, such as the red wavelength region or the blue wavelength region. Therefore, the conventional apparatuses for displaying a fluorescence image described above have the problems in that the efficiency, with which the fluorescence is utilized, cannot be kept high, adverse effects of photon noise, and the like, are apt to occur during photoelectric conversion, and a signal-to-noise ratio of the fluorescence image cannot be kept high.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide an apparatus for displaying a fluorescence image, wherein an efficiency, with which fluorescence having been produced from a measuring site in a living body exposed to excitation light, is utilized, is enhanced, and a signal-to-noise ratio of a displayed fluorescence image is kept high.
Another object of the present invention is to provide an apparatus for displaying a fluorescence image, wherein a fluorescence image is capable of being displayed in a real time mode, and a reliability of the displayed fluorescence image is capable of being enhanced.
The present invention provides a first apparatus for displaying a fluorescence image, comprising:
i) excitation light irradiating means for irradiating excitation light to a measuring site in a living body, the excitation light causing the measuring site to produce fluorescence,
ii) image information acquiring means for acquiring image information in accordance with a signal intensity of fluorescence components of the fluorescence having been produced from the measuring site exposed to the excitation light, which fluorescence components have wavelengths falling within at least one desired wavelength region, and
iii) displaying means for displaying the acquired image information,
wherein the image information acquiring means comprises:
a) a complementary color filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a wavelength region acting as a complementary color with respect to the desired wavelength region,
b) complementary color signal intensity detecting means for detecting a signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the complementary color filter,
c) entire signal intensity detecting means for detecting a signal intensity of fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within an entire measurement wavelength region of the fluorescence, and
d) signal intensity calculating means for calculating the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the desired wavelength region, from the signal intensity, which has been detected by the complementary color signal intensity detecting means, and the signal intensity, which has been detected by the entire signal intensity detecting means.
In the first apparatus for displaying a fluorescence image in accordance with the present invention, the entire signal intensity detecting means should preferably comprise an all-pass filter for transmitting the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the entire measurement wavelength region of the fluorescence, and
entire measurement signal intensity detecting means for detecting the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the all-pass filter.
In such cases, a plurality of complementary color filters and a plurality of all-pass filters should preferably be arrayed alternately on a two-dimensional plane so as to constitute a mosaic filter.
The present invention also provides a second apparatus for displaying a fluorescence image, comprising:
i) excitation light irradiating means for irradiating excitation light to a measuring site in a living body, the excitation light causing the measuring site to produce fluorescence,
ii) image information acquiring means for acquiring image information in accordance with a signal intensity of fluorescence components of the fluorescence having been produced from the measuring site exposed to the excitation light, which fluorescence components have wavelengths falling within at least one desired wavelength region selected from among a blue wavelength region, a green wavelength region, and a red wavelength region, and
iii) displaying means for displaying the acquired image information,
wherein the image information acquiring means comprises:
a) a yellow filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a yellow wavelength region acting as a complementary color with respect to the blue wavelength region,
b) a magenta filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a magenta wavelength region acting as a complementary color with respect to the green wavelength region,
c) a cyan filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a cyan wavelength region acting as a complementary color with respect to the red wavelength region,
d) complementary color signal intensity detecting means for detecting a signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the yellow filter, a signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the magenta filter, and a signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the cyan filter,
e) entire signal intensity calculating means for calculating a signal intensity of fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within an entire measurement wavelength region of the fluorescence, from the signal intensity of the fluorescence components having wavelengths falling within the yellow wavelength region, the signal intensity of the fluorescence components having wavelengths falling within the magenta wavelength region, and the signal intensity of the fluorescence components having wavelengths falling within the cyan wavelength region, which signal intensities have been detected by the complementary color signal intensity detecting means, and
f) signal intensity calculating means for calculating the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the desired wavelength region, from the signal intensities, which have been detected by the complementary color signal intensity detecting means, and the signal intensity of the fluorescence components having wavelengths falling within the entire measurement wavelength region of the fluorescence, which signal intensity has been calculated by the entire signal intensity calculating means.
In the second apparatus for displaying a fluorescence image in accordance with the present invention, a plurality of yellow filters, a plurality of magenta filters, and a plurality of cyan filters should preferably be arrayed alternately on a two-dimensional plane so as to constitute a mosaic filter.
In the first and second apparatuses for displaying a fluorescence image in accordance with the present invention, the image information acquiring means may employ one of various techniques for acquiring the image information. For example, the image information acquiring means may employ a technique for acquiring the image information in accordance with the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within only one desired wavelength region. Alternatively, the image information acquiring means may employ a technique for acquiring the image information in accordance with a ratio among the signal intensities of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a plurality of desired wavelength regions.
Also, in the first and second apparatuses for displaying a fluorescence image in accordance with the present invention, the displaying means may employ one of various displaying techniques. For example, in cases where the image information acquiring means acquires the image information in accordance with the ratio among the signal intensities of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the plurality of the desired wavelength regions, the ratio among the signal intensities may be displayed on a monitor, with a printer, or the like. Alternatively, a tint of a display color or luminance may be altered in accordance with the ratio among the signal intensities.
The term “all-pass filter” as used herein also includes a blank area for transmitting the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the entire wavelength region of the fluorescence.
With the first apparatus for displaying a fluorescence image in accordance with the present invention, the signal intensity of the fluorescence components, which have wavelengths falling within the desired wavelength region, is calculated from the signal intensity of the fluorescence components, which have wavelengths falling within the wavelength region acting as the complementary color with respect to the desired wavelength region, and the signal intensity of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region of the fluorescence. Therefore, the efficiency, with which the fluorescence having been produced from the measuring site is utilized, is capable of being enhanced. Accordingly, adverse effects of noise are capable of being reduced, and the signal-to-noise ratio of the displayed fluorescence image is capable of being kept high.
Also, with the first apparatus for displaying a fluorescence image in accordance with the present invention, wherein the signal intensity of the fluorescence components, which have wavelengths falling within the desired wavelength region, is calculated from the signal intensity of the fluorescence components, which have passed through the all-pass filter for transmitting the fluorescence components having wavelengths falling within the entire measurement wavelength region of the fluorescence, the fluorescence having been produced from the measuring site is capable of being utilized most efficiently, and the signal-to-noise ratio of the displayed fluorescence image is capable of being enhanced even further.
The second apparatus for displaying a fluorescence image in accordance with the present invention is provided with the yellow filter for transmitting only the fluorescence components, which have wavelengths falling within the yellow wavelength region acting as the complementary color with respect to the blue wavelength region, the magenta filter for transmitting only the fluorescence components, which have wavelengths falling within the magenta wavelength region acting as the complementary color with respect to the green wavelength region, and the cyan filter for transmitting only the fluorescence components, which have wavelengths falling within the cyan wavelength region acting as the complementary color with respect to the red wavelength region. Also, the signal intensity of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region of the fluorescence, is calculated from the signal intensity of the fluorescence components, which have passed through the yellow filter, the signal intensity of the fluorescence components, which have passed through the magenta filter, and the signal intensity of the fluorescence components, which have passed through the cyan filter. Thereafter, the signal intensity of the fluorescence components, which have wavelengths falling within the at least one desired wavelength region selected from among the blue wavelength region, the green wavelength region, and the red wavelength region, is calculated from the signal intensity of the fluorescence components, which have passed through the yellow filter, the signal intensity of the fluorescence components, which have passed through the magenta filter, the signal intensity of the fluorescence components, which have passed through the cyan filter, and the signal intensity of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region of the fluorescence. Therefore, the efficiency, with which the fluorescence having been produced from the measuring site is utilized, is capable of being enhanced. Accordingly, adverse effects of noise are capable of being reduced, and the signal-to-noise ratio of the displayed fluorescence image is capable of being kept high. Further, the three kinds of the filters are capable of being utilized also as color filters for acquiring ordinary color images, and therefore the cost of the apparatus for displaying a fluorescence image is capable of being kept low.
With the first apparatus for displaying a fluorescence image in accordance with the present invention, wherein the plurality of the complementary color filters and the plurality of the all-pass filters are arrayed alternately on a two-dimensional plane so as to constitute the mosaic filter, or with the second apparatus for displaying a fluorescence image in accordance with the present invention, wherein the plurality of the yellow filters, the plurality of the magenta filters, and the plurality of the cyan filters are arrayed alternately on a two-dimensional plane so as to constitute the mosaic filter, the signal intensity of the fluorescence components, which have wavelengths falling within the desired wavelength region, is capable of being calculated from the signal intensities of the fluorescence components having wavelengths falling within the respective wavelength regions, which signal intensities have been detected simultaneously. Therefore, the fluorescence image is capable of being displayed in the real time mode, and the reliability of the displayed fluorescence image is capable of being enhanced.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic view showing an endoscope system, in which a first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 2
is a graph showing transmission wavelength regions of band-pass filters constituting a mosaic filter for a fluorescence image employed in the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 3
is a schematic view showing the mosaic filter for a fluorescence image employed in the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 4
is a block diagram showing a signal processing circuit employed in the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 5
is a timing chart employed in the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 6
is a schematic view showing an endoscope system, in which a second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 7
is a graph showing transmission wavelength regions of band-pass filters constituting a mosaic filter employed in the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 8
is a schematic view showing the mosaic filter employed in the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 9
is a timing chart employed in the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 10
is a schematic view showing an endoscope system, in which a third embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed,
FIG. 11
is a graph showing transmission wavelength regions of band-pass filters constituting a mosaic filter employed in an endoscope system, in which a modification of the embodiments of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, and
FIG. 12
is a graph showing spectral intensity distributions of fluorescence produced from normal tissues and fluorescence produced from diseased tissues.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will hereinbelow be described in further detail with reference to the accompanying drawings.
Firstly, an endoscope system, in which a first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, will be described hereinbelow with reference to
FIG. 1
to FIG.
5
.
FIG. 1
is a schematic view showing the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed. In the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, excitation light is irradiated to a measuring site in a living body, the excitation light causing the measuring site to produce fluorescence. The fluorescence produced from the measuring site is two-dimensionally acquired as a fluorescence image and with an image fiber. The fluorescence image is detected by a charge coupled device (CCD) image sensor combined with a mosaic filter constituted of an array of yellow filters for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a wavelength region of at least 510 nm, and blank areas for transmitting fluorescence components of the fluorescence, which have wavelengths falling within an entire measurement wavelength region. In this manner, signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the wavelength region of at least 510 nm, and signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the entire measurement wavelength region, are detected. Further, signal intensity of fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a blue wavelength region of at most 510 nm, is calculated from the thus detected two signal intensities. Thereafter, image information is displayed on a monitor as a pseudo color image in accordance with a ratio between the signal intensity of fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the blue wavelength region, and the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the entire measurement wavelength region.
The endoscope system, in which the first embodiment of the apparatus for displaying fluorescence information in accordance with the present invention is employed, comprises an endoscope
100
to be inserted into a region of a patient, which region is considered as being a diseased part, and an illuminating unit
110
provided with light sources for producing white light, which is used when an ordinary image is to be displayed, and the excitation light, which is used when a fluorescence image is to be displayed. The endoscope system also comprises a fluorescence imaging unit
120
for receiving the fluorescence, which is produced from the measuring site in the living body when the measuring site is exposed to the excitation light, and detecting the image of the fluorescence. The endoscope system further comprises a fluorescence image processing unit
130
for performing image processing for displaying the fluorescence image as a pseudo color image in accordance with the ratio between signal intensities of fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within predetermined wavelength regions. The endoscope system still further comprises an ordinary image processing unit
140
for performing image processing for displaying an ordinary image as a color image. The endoscope system also comprises a display image processing unit
150
for superimposing the color image of the ordinary image and the pseudo color image of the fluorescence image one upon the other. The endoscope system further comprises a controller
160
, which is connected to the respective units and controls operation timings. The endoscope system still further comprises a monitor
170
for displaying the ordinary image (specifically, the color image of the ordinary image) and the fluorescence image (specifically, the pseudo color image of the fluorescence image), which have been superimposed one upon the other by the display image processing unit
150
.
A light guide
101
, a CCD cable
102
, and an image fiber
103
extend in the endoscope
100
up to a leading end of the endoscope
100
. An illuminating lens
104
is located at a leading end of the light guide
101
, i.e. at the leading end of the endoscope
100
. An objective lens
105
is located at a leading end of the CCD cable
102
, i.e. at the leading end of the endoscope
100
. The image fiber
103
is constituted of glass fibers, and a converging lens
106
is located at a leading end of the image fiber
103
. A CCD image sensor
108
is connected to the leading end of the CCD cable
102
. A mosaic filter
107
, which comprises fine band-pass filters arrayed in a mosaic form, is combined with the CCD image sensor
108
. Also, a prism
109
is mounted on the CCD image sensor
108
.
The mosaic filter
107
is a complementary color type of filter, which is constituted of color filters having colors acting as complementary colors with respect to the three primary colors. Each of the color filters of the mosaic filter
107
corresponds to one of pixels in the CCD image sensor
108
.
The light guide
101
comprises a white light guide
101
a
, which is constituted of a compound glass fiber, and an excitation light guide
101
b
, which is constituted of a quartz glass fiber. The white light guide
101
a
and the excitation light guide
101
b
are bundled together in a cable-like form to constitute the light guide
101
. The white light guide
101
a
and the excitation light guide
101
b
are connected to the illuminating unit
110
. A tail end of the CCD cable
102
is connected to the ordinary image processing unit
140
. A tail end of the image fiber
103
is connected to the fluorescence imaging unit
120
.
The illuminating unit
110
comprises a white light source
111
for producing white light L
1
, which is used when an ordinary image is to be displayed, and an electric power source
112
, which is electrically connected to the white light source
111
. The illuminating unit
110
also comprises a GaN type of semiconductor laser
114
for producing excitation light L
3
, which is used when a fluorescence image is to be displayed, and an electric power source
115
, which is electrically connected to the GaN type of semiconductor laser
114
.
The fluorescence imaging unit
120
comprises an excitation light cut-off filter
121
for filtering out light, which has wavelengths falling within a wavelength region of at most 430 nm in the vicinity of the wavelength of the excitation light L
3
, from fluorescence L
4
having passed through the image fiber
103
. The fluorescence imaging unit
120
also comprises a CCD image sensor
125
, which is constituted of a cooled, back exposure type of CCD image sensor. The CCD image sensor
125
is combined with a mosaic filter
123
, which comprises two kinds of band-pass filters combined with each other in a mosaic-like form.
As illustrated in
FIG. 3
, the mosaic filter
123
is constituted of yellow filters
124
a
,
124
a
, . . . and blank areas
124
b
,
124
b
, . . . , which are arrayed alternately. The yellow filters
124
a
,
124
a
, . . . are band-pass filters, which transmit only light having wavelengths falling within a wavelength region (a) of at least 510 nm illustrated in FIG.
2
. The blank areas
124
b
,
124
b
, . . . transmit light having wavelengths falling within an entire measurement wavelength region (b) illustrated in FIG.
2
. Each of the yellow filters
124
a
,
124
a
, . . . and the blank areas
124
b
,
124
b
, . . . corresponds to one of pixels in the CCD image sensor
125
.
The fluorescence image processing unit
130
comprises a signal processing circuit
131
for forming pseudo color image signals from the fluorescence image, which has been detected by the CCD image sensor
125
. The fluorescence image processing unit
130
also comprises an analog-to-digital converting circuit
132
for digitizing the pseudo color image signals, which have been obtained from the signal processing circuit
131
. The fluorescence image processing unit
130
further comprises a fluorescence image memory
133
for storing the digital pseudo color image signals, which have been obtained from the analog-to-digital converting circuit
132
. The fluorescence image processing unit
130
still further comprises a digital-to-analog converting circuit
134
for performing digital-to-analog conversion on the pseudo color image signals, which have been received from the fluorescence image memory
133
. The fluorescence image processing unit
130
also comprises a fluorescence image encoder
135
for transforming the pseudo color image signals, which have been received from the digital-to-analog converting circuit
134
, into video signals.
As illustrated in
FIG. 4
, the signal processing circuit
131
comprises a process circuit
136
for performing sampling, clamping, blanking, amplification, and the like, on the signals having been obtained from the CCD image sensor
125
. The signal processing circuit
131
also comprises a complementary color-to-primary color matrix operation circuit
137
for calculating the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the blue wavelength region, from the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the yellow filters
124
a
,
124
a
, . . . , and the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the blank areas
124
b
,
124
b
, . . . . The signal processing circuit
131
further comprises an image signal matrix operation circuit
138
for forming the pseudo color image signals from the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the blue wavelength region, and the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the entire measurement wavelength region.
The ordinary image processing unit
140
comprises a signal processing circuit
141
for forming color image signals from the ordinary image, which has been detected by the CCD image sensor
108
. The ordinary image processing unit
140
also comprises an analog-to-digital converting circuit
142
for digitizing the color image signals, which have been obtained from the signal processing circuit
141
. The ordinary image processing unit
140
further comprises an ordinary image memory
143
for storing the digital color image signals, which have been obtained from the analog-to-digital converting circuit
142
. The ordinary image processing unit
140
still further comprises a digital-to-analog converting circuit
144
for performing digital-to-analog conversion on the color image signals, which have been received from the ordinary image memory
143
. The ordinary image processing unit
140
also comprises an ordinary image encoder
145
for transforming the color image signals, which have been received from the digital-to-analog converting circuit
144
, into video signals.
The display image processing unit
150
comprises a superimposer
151
for superimposing the pseudo color image signals, which have been received from the fluorescence image encoder
135
, and the color image signals, which have been received from the ordinary image encoder
145
, one upon the other, and feeding out the thus obtained image signals as the display signals. The display image processing unit
150
also comprises an RGB decoder
152
for transforming the display signals, which are the video signals, into R, G, and B display signals.
How the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, operates will be described hereinbelow. Firstly, how the endoscope system operates when an ordinary image is to be displayed will be described hereinbelow.
When an ordinary image is to be displayed, the electric power source
112
for the white light source
111
is driven in accordance with a control signal fed from the controller
160
, and the white light L
1
is produced by the white light source
111
. The white light L
1
passes through a lens
113
and impinges upon the white light guide
101
a
. The white light L
1
is guided through the white light guide
101
a
to the leading end of the endoscope
100
, passes through the illuminating lens
104
, and is irradiated to a measuring site
10
. The white light L
1
is reflected as reflected light L
2
from the measuring site
10
. The reflected light L
2
is converged by the objective lens
105
and reflected by the prism
109
. The reflected light L
2
then passes through the mosaic filter
107
, is received by the CCD image sensor
108
, and is photoelectrically converted into electric signals.
In the signal processing circuit
141
, the processes, such as correlative double sampling, clamping, blanking, and amplification, are performed on the signals having been obtained from the CCD image sensor
108
. Thereafter, the resulting signals are subjected to Y/C separation for separating a luminance signal and chrominance signals from one another. Thereafter, Y signal processing is performed, and a luminance signal Y
1
is calculated. Also, complementary color signals, which have been separated from one another by the mosaic filter
107
combined with the CCD image sensor
108
, are transformed into primary color signals (with complementary color-to-primary color transform). From the thus obtained primary color signals, color difference signals R
1
−Y
1
and B
1
−Y
1
are calculated with color difference matrix transform according to an NTSC method.
The color image signals (i.e., the luminance signal Y
1
and the color difference signals R
1
−Y
1
and B
1
−Y
1
), which are made up of color image signal components corresponding to respective pixels and have been obtained from the signal processing circuit
141
, are digitized by the analog-to-digital converting circuit
142
. The thus obtained luminance signal Y
1
is stored in a luminance signal storage area of the ordinary image memory
143
. The color difference signals R
1
−Y
1
and B
1
−Y
1
are stored in color difference signal storage areas of the ordinary image memory
143
.
In accordance with a display timing, the color image signals (i.e., the luminance signal Y
1
and the color difference signals R
1
−Y
1
and B
1
−Y
1
) having been stored in the ordinary image memory
143
are subjected to the digital-to-analog conversion in the digital-to-analog converting circuit
144
and transformed by the ordinary image encoder
145
into predetermined video signals. The thus obtained video signals are fed into the superimposer
151
and superimposed upon the pseudo color image signals, which are obtained in the manner described later. The superimposed video signals are fed into the monitor
170
and the RGB decoder
152
. How the monitor
170
and the RGB decoder
152
operate will be described later.
How the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, operates when a fluorescence image is to be displayed will be described hereinbelow.
When a fluorescence image is to be displayed, the electric power source
115
for the GaN type of semiconductor laser
114
is driven in accordance with a control signal fed from the controller
160
, and the excitation light L
3
having a wavelength of 410 nm is produced by the GaN type of semiconductor laser
114
. The excitation light L
3
passes through a lens
116
and impinges upon the excitation light guide
101
b
. The excitation light L
3
is guided through the excitation light guide
101
b
to the leading end of the endoscope
100
, passes through the illuminating lens
104
, and is irradiated to the measuring site
10
.
When the measuring site
10
is exposed to the excitation light L
3
, the fluorescence L
4
is produced from the measuring site
10
. The fluorescence L
4
is converged by the converging lens
106
and impinges upon the leading end of the image fiber
103
. The fluorescence L
4
then passes through the image fiber
103
and impinges upon the excitation light cut-off filter
121
of the fluorescence imaging unit
120
.
Thereafter, the fluorescence L
4
is converged by a lens
122
and passes through the mosaic filter
123
, which is combined with the CCD image sensor
125
. In this manner, an image of the fluorescence L
4
is formed on the CCD image sensor
125
. Specifically, with the photoelectric conversion performed by the CCD image sensor
125
, the image of the fluorescence L
4
is converted into electric signals in accordance with the intensity of the fluorescence L
4
.
In the process circuit
136
of the signal processing circuit
131
, the processes, such as correlative double sampling, clamping, blanking, and amplification, are performed on the signals having been obtained from the CCD image sensor
125
. The signals having been obtained from the processes are fed as two-dimensional signals into the complementary color-to-primary color matrix operation circuit
137
. Thereafter, in the complementary color-to-primary color matrix operation circuit
137
, a signal intensity B
2
of the fluorescence components of the fluorescence L
4
, which fluorescence components have wavelengths falling within the blue wavelength region, is calculated for each pixel in the manner described below. Specifically, matrix operations with Formula (1) shown below are performed by utilizing a signal intensity Ye
2
of the fluorescence components, which have wavelengths falling within the yellow wavelength region (i.e., green+red) and have passed through the yellow filters
124
a
,
124
a
, . . . , and a signal intensity W
2
of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region and have passed through the blank areas
124
b
,
124
b
, . . . . Each of the matrix operations is performed by utilizing the signal intensities corresponding to pixels adjacent to each pixel.
More specifically, the signal intensity B
2
is calculated with the formula shown below.
B
2=
W
2−
Ye
2
Further, in the image signal matrix operation circuit
138
, color difference matrix operations according to the NTSC method are performed by utilizing the signal intensity B
2
and the signal intensity W
2
. In this manner, a pseudo luminance signal Y
2
and pseudo color difference signals R
2
−Y
2
and B
2
−Y
2
, which act as the pseudo color image signals, are calculated with matrix operations represented by Formula (2) shown below.
Therefore, the pseudo luminance signal Y
2
and the pseudo color difference signals R
2
−Y
2
and B
2
−Y
2
are calculated with the formulas shown below.
The pseudo color image signals (i.e., the pseudo luminance signal Y
2
and the pseudo color difference signals R
2
−Y
2
and B
2
−Y
2
), which are made up of pseudo color image signal components corresponding to respective pixels and have been obtained from the signal processing circuit
131
, are digitized by the analog-to-digital converting circuit
132
. The thus obtained pseudo luminance signal Y
2
is stored in a luminance signal storage area of the fluorescence image memory
133
. Also, the thus obtained pseudo color difference signals R
2
−Y
2
and B
2
−Y
2
are stored in color difference signal storage areas of the fluorescence image memory
133
. In accordance with the display timing, the pseudo color image signals (i.e., the pseudo luminance signal Y
2
and the pseudo color difference signals R
2
−Y
2
and B
2
−Y
2
) having been stored in the fluorescence image memory
133
are subjected to the digital-to-analog conversion in the digital-to-analog converting circuit
134
and transformed by the fluorescence image encoder
135
into predetermined video signals. The thus obtained video signals are fed from the fluorescence image encoder
135
into the superimposer
151
. In the superimposer
151
, the pseudo color image signals are superimposed upon the color image signals (i.e., the luminance signal Y
1
and the color difference signals R
1
−Y
1
and B
1
−Y
1
), which represent the ordinary image and have been received from the ordinary image encoder
145
. The thus obtained video signals are fed into the monitor
170
and the RGB decoder
152
.
The monitor
170
transforms the color image signals and the pseudo color image signals, which have been received as the video signals, and reproduces an ordinary image
30
and a fluorescence image
31
from the image signals having been obtained from the transform. The fluorescence image
31
is displayed with a pseudo color, such that the display color varies in accordance with the ratio between the signal intensity W
2
of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region, and the signal intensity B
2
of the fluorescence components, which have wavelengths falling within the blue wavelength region. The tint of the pseudo color of the fluorescence image
31
is determined by the coefficients (a
1
, a
2
, b
1
, b
2
, c
1
, and c
2
) in the matrix operation formulas employed in the image signal matrix operation circuit
138
.
The coefficients described above should preferably be selected such that the difference between the display color for the fluorescence, which has been produced from the normal tissues, and the display color for the fluorescence, which has been produced from the diseased tissues, may be clear. For example, the pseudo color may be displayed by selecting the coefficients such that the fluorescence, which has been produced from the normal tissues, may be displayed in white, and the fluorescence, which has been produced from the diseased tissues, may be displayed in pink or in one of other colors. In such cases, the person, who sees the displayed image, is capable of easily recognizing the state of the diseased tissues.
In the RGB decoder
152
, the color signals R, G, and B representing the ordinary image and the color signals R, G, and B representing the fluorescence image are inversely transformed from the color image signals and the pseudo color image signals, which have been superimposed one upon the other. The color signals R, G, and B are fed into a device (not shown) capable of directly receiving the color signals, such as a printer or an image processing unit.
The series of operations described above are controlled by the controller
160
and are performed in accordance with a timing chart illustrated in FIG.
5
. As illustrated in
FIG. 5
, the irradiation of the white light L
1
and the exposure of the CCD image sensor
108
to the reflected light L
2
are performed synchronously every {fraction (1/30)} second. The irradiation of the excitation light L
3
and the exposure of the CCD image sensor
125
to the fluorescence L
4
are performed during a period, in which the irradiation of the white light L
1
is ceased, i.e. during a period corresponding to a vertical blanking period in a television system. Therefore, the detection of the ordinary image is not obstructed by the detection of the fluorescence image. Also, since each of the ordinary image and the fluorescence image is detected every {fraction (1/30)} second, the ordinary image
30
and the fluorescence image
31
are displayed on the monitor
170
as dynamic images, which are updated every {fraction (1/30)} second.
As described above, with the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, the signal intensity W
2
of the entire measurement wavelength region and the signal intensity Ye
2
of the wavelength region of at least 510 nm are detected from the fluorescence L
4
, which is produced from the measuring site
10
when the measuring site
10
is exposed to the excitation light L
3
. Also, the signal intensity B
2
of the blue wavelength region of at most 510 nm is calculated from the signal intensity W
2
and the signal intensity Ye
2
. The display color in accordance with the ratio between the signal intensity W
2
and the signal intensity B
2
is displayed by the utilization of an additive color mixture process. Therefore, the efficiency, with which the fluorescence L
4
having been produced from the measuring site
10
is utilized, is capable of being enhanced. Accordingly, adverse effects of noise are capable of being reduced, and the signal-to-noise ratio of the displayed fluorescence image is capable of being kept high.
Further, the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, is provided with the mosaic filter
123
provided with the blank areas
124
b
,
124
b
, . . . , which transmit the fluorescence components having wavelength falling within the entire measurement wavelength region. Therefore, the fluorescence L
4
having been produced from the measuring site
10
is capable of being utilized most efficiently, and the signal-to-noise ratio of the displayed fluorescence image is capable of being enhanced even further. Furthermore, the signal intensities of the respective wavelength regions are capable of being detected simultaneously, and the signal intensity of the desired wavelength region is capable of being obtained in a real time mode. Therefore, the reliability of the displayed fluorescence image is capable of being enhanced.
In the endoscope system, in which the first embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, the mosaic filter
123
is constituted of the yellow filters
124
a
,
124
a
, . . . , which transmit only the fluorescence components having wavelengths falling within the wavelength region of at least 510 nm, and the blank areas
124
b
,
124
b
, . . . , which transmit the fluorescence components having wavelengths falling within the entire measurement wavelength region. The mosaic filter
123
is combined with the CCD image sensor
125
. With the CCD image sensor
125
, the signal intensity Ye
2
of the fluorescence components, which have wavelengths falling within the wavelength region of at least 510 nm, and the signal intensity W
2
of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region, are detected. Also, the signal intensity B
2
of the fluorescence components, which have wavelengths falling within the blue wavelength region of at most 510 nm, is calculated from the signal intensity Ye
2
and the signal intensity W
2
. Further, the pseudo color image in accordance with the ratio between the signal intensity B
2
of the blue wavelength region and the signal intensity W
2
of the entire measurement wavelength region is displayed. Alternatively, in a modification of the first embodiment, the mosaic filter
123
may be replaced by a mosaic filter constituted of cyan filters, which transmit only the fluorescence components having wavelengths falling within a wavelength region of at most 600 nm, and the blank areas, which transmit the fluorescence components having wavelengths falling within the entire measurement wavelength region. In such cases, with a CCD image sensor combined with the mosaic filter, a signal intensity of the wavelength region of at most 600 nm and the signal intensity of the entire measurement wavelength region may be detected, and a signal intensity of a red wavelength region of at least 600 nm may be calculated from the two detected signal intensities. Also, a pseudo color image in accordance with the ratio between the signal intensity of the red wavelength region and signal intensity of the entire measurement wavelength region may be displayed.
The ratio between the signal intensity of the red wavelength region and signal intensity of the entire measurement wavelength region varies for the fluorescence produced from the normal tissues and the fluorescence produced from the diseased tissues. Therefore, with the modification of the first embodiment, the same effects as those with the first embodiment are capable of being obtained.
An endoscope system, in which a second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, will be described hereinbelow with reference to
FIG. 6
to FIG.
9
.
FIG. 6
is a schematic view showing the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed. In the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, excitation light is irradiated to a measuring site in a living body. Fluorescence produced from the measuring site is received by a CCD image sensor, which is located at a leading end of an endoscope and is utilized also for detecting an ordinary image. In this manner, a detected fluorescence image is displayed on the monitor.
The endoscope system, in which the second embodiment of the apparatus for displaying fluorescence information in accordance with the present invention is employed, comprises an endoscope
200
to be inserted into a region of a patient, which region is considered as being a diseased part, and an illuminating unit
210
provided with light sources for producing white light L
5
, which is used when an ordinary image is to be displayed, and excitation light L
7
, which is used when a fluorescence image is to be displayed. The endoscope system also comprises a fluorescence image processing unit
220
for performing image processing for displaying a fluorescence image as a pseudo color image, and an ordinary image processing unit
230
for performing image processing for displaying an ordinary image as a color image. The endoscope system further comprises a display image processing unit
240
for superimposing the ordinary image and the fluorescence image one upon the other. The endoscope system still further comprises a controller
250
, which is connected to the respective units and controls operation timings. The endoscope system also comprises the monitor
170
for displaying the display images, which have been superimposed one upon the other by the display image processing unit
240
.
A light guide
201
and a CCD cable
202
extend in the endoscope
200
up to a leading end of the endoscope
200
. An illuminating lens
203
is located at a leading end of the light guide
201
, i.e. at the leading end of the endoscope
200
. An objective lens
204
is located at a leading end of the CCD cable
202
, i.e. at the leading end of the endoscope
200
. A CCD image sensor
206
, which is constituted of a cooled, back exposure type of CCD image sensor, is connected to the leading end of the CCD cable
202
. A mosaic filter
205
, which comprises fine band-pass filters arrayed in a mosaic form, is combined with the CCD image sensor
206
. Also, a prism
207
is mounted on the CCD image sensor
206
. An excitation light cut-off filter
208
for filtering out light, which has wavelengths falling within a wavelength region of at most 430 nm in the vicinity of the wavelength of the excitation light L
7
, is located between the prism
207
and the objective lens
204
.
As illustrated in
FIG. 8
, the mosaic filter
205
is constituted of yellow filters
205
a
,
205
a
, . . . , cyan filters
205
b
,
205
b
, . . . , and blank areas
205
c
,
205
c
, . . . , which are arrayed alternately. The yellow filters
205
a
,
205
a
, . . . are band-pass filters, which transmit only light having wavelengths falling within a wavelength region (a) of at least 510 nm illustrated in FIG.
7
. The cyan filters
205
b
,
205
b
, . . . are band-pass filters, which transmit only light having wavelengths falling within a wavelength region (b) of at most 600 nm illustrated in FIG.
7
. The blank areas
205
c
,
205
c
, . . . transmit light having wavelengths falling within an entire measurement wavelength region (c) illustrated in FIG.
7
.
The light guide
201
comprises a white light guide
201
a
, which is constituted of a compound glass fiber, and an excitation light guide
201
b
, which is constituted of a quartz glass fiber. The white light guide
201
a
and the excitation light guide
201
b
are bundled together in a cable-like form to constitute the light guide
201
. The white light guide
201
a
and the excitation light guide
201
b
are connected to the illuminating unit
210
. A tail end of the CCD cable
202
is connected to the fluorescence image processing unit
220
and the ordinary image processing unit
230
.
The illuminating unit
210
comprises a white light source
211
for producing the white light L
5
, which is used when an ordinary image is to be displayed, and an electric power source
212
, which is electrically connected to the white light source
211
. The illuminating unit
210
also comprises a GaN type of semiconductor laser
214
for producing the excitation light L
7
, which is used when a fluorescence image is to be displayed, and an electric power source
215
, which is electrically connected to the GaN type of semiconductor laser
214
.
The fluorescence image processing unit
220
comprises a signal processing circuit
221
for forming pseudo color image signals from a fluorescence image, which has been detected by the CCD image sensor
206
. The fluorescence image processing unit
220
also comprises an analog-to-digital converting circuit
222
for digitizing the pseudo color image signals, which have been obtained from the signal processing circuit
221
. The fluorescence image processing unit
220
further comprises a fluorescence image memory
223
for storing the digital pseudo color image signals, which have been obtained from the analog-to-digital converting circuit
222
. The fluorescence image processing unit
220
still further comprises a digital-to-analog converting circuit
224
for performing digital-to-analog conversion on the pseudo color image signals, which have been received from the fluorescence image memory
223
. The fluorescence image processing unit
220
also comprises a fluorescence image encoder
225
for transforming the pseudo color image signals, which have been received from the digital-to-analog converting circuit
224
, into video signals.
As illustrated in
FIG. 4
, the signal processing circuit
221
comprises a process circuit
226
for performing image processing. The signal processing circuit
221
also comprises a complementary color-to-primary color matrix operation circuit
227
for calculating the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the blue wavelength region, and the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the red wavelength region, from the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the yellow filters
205
a
,
205
a
, . . . , the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the cyan filters
205
b
,
205
b
, . . . , and the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the blank areas
205
c
,
205
c
, . . . . The signal processing circuit
221
further comprises an image signal matrix operation circuit
228
for forming the pseudo color image signals from the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the blue wavelength region, and the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the red wavelength region.
The ordinary image processing unit
230
comprises a signal processing circuit
231
for forming color image signals from the ordinary image, which has been detected by the CCD image sensor
206
. The ordinary image processing unit
230
also comprises an analog-to-digital converting circuit
232
for digitizing the color image signals, which have been obtained from the signal processing circuit
231
. The ordinary image processing unit
230
further comprises an ordinary image memory
233
for storing the digital color image signals, which have been obtained from the analog-to-digital converting circuit
232
. The ordinary image processing unit
230
still further comprises a digital-to-analog converting circuit
234
for performing digital-to-analog conversion on the color image signals, which have been received from the ordinary image memory
233
. The ordinary image processing unit
230
also comprises an ordinary image encoder
235
for transforming the color image signals, which have been received from the digital-to-analog converting circuit
234
, into video signals.
As illustrated in
FIG. 4
, the signal processing circuit
231
comprises a process circuit
236
for performing image processing. The signal processing circuit
231
also comprises a complementary color-to-primary color matrix operation circuit
237
for calculating the signal intensities of the three primary colors, i.e., the signal intensities of the blue wavelength region, the green wavelength region, and the red wavelength region, from the signal intensity of the light components, which have passed through the yellow filters
205
a
,
205
a
, . . . , the signal intensity of the light components, which have passed through the cyan filters
205
b
,
205
b
, . . . , and the signal intensity of the light components, which have passed through the blank areas
205
c
,
205
c
, . . . . The signal processing circuit
231
further comprises an image signal matrix operation circuit
238
for forming the color image signals from the signal intensities of the three primary colors.
How the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, operates will be described hereinbelow. Firstly, how the endoscope system operates when an ordinary image is to be displayed will be described hereinbelow.
When an ordinary image is to be displayed, the electric power source
212
for the white light source
211
is driven in accordance with a control signal fed from the controller
250
, and the white light L
5
is produced by the white light source
211
. The white light L
5
passes through a lens
213
and impinges upon the white light guide
201
a
. The white light L
5
is guided through the white light guide
201
a
to the leading end of the endoscope
200
, passes through the illuminating lens
203
, and is irradiated to a measuring site
20
. The white light L
5
is reflected as reflected light L
6
from the measuring site
20
. The reflected light L
6
is converged by the objective lens
204
, passes through the excitation light cut-off filter
208
, and is reflected by the prism
207
. The reflected light L
6
then passes through the mosaic filter
205
and is received by the CCD image sensor
206
.
In the process circuit
236
of the signal processing circuit
231
, the processes are performed on the signals having been obtained from the CCD image sensor
206
. Thereafter, in the complementary color-to-primary color matrix operation circuit
237
, a signal intensity B
3
of the light components of the reflected light L
6
, which light components have wavelengths falling within the blue wavelength region, a signal intensity G
3
of the light components of the reflected light L
6
, which light components have wavelengths falling within the green wavelength region, and a signal intensity R
3
of the light components of the reflected light L
6
, which light components have wavelengths falling within the red wavelength region, are calculated for each pixel in the manner described below. Specifically, matrix operations with Formula (3) shown below are performed by utilizing a signal intensity Ye
3
of the light components, which have wavelengths falling within the yellow wavelength region (i.e., green+red) and have passed through the yellow filters
205
a
,
205
a
, . . . , a signal intensity Cy
3
of the light components, which have wavelengths falling within the cyan wavelength region (i.e., blue+green) and have passed through the cyan filters
205
b
,
205
b
, . . . , and a signal intensity W
3
of the light components, which have wavelengths falling within the entire measurement wavelength region and have passed through the blank areas
205
c
,
205
c
, . . . . Each of the matrix operations is performed by utilizing the image signal components corresponding to pixels adjacent to each pixel.
More specifically, the calculations are made with the formula shown below.
R
3=
W
3−
Cy
3
G
3=−
W
3+
Ye
3+
Cy
3
B
3=
W
3−
Ye
3
Further, in the image signal matrix operation circuit
238
, matrix operations according to the NTSC method are performed by utilizing the signal intensity B
3
of the light components, which have wavelengths falling within the blue wavelength region, the signal intensity G
3
of the light components, which have wavelengths falling within the green wavelength region, and the signal intensity R
3
of the light components, which have wavelengths falling within the red wavelength region. In this manner, a luminance signal Y
3
and color difference signals R
3
−Y
3
and B
3
−Y
3
, which act as the color image signals, are calculated with matrix operations represented by Formula (4) shown below.
Specifically, the luminance signal Y
3
and the color difference signals R
3
−Y
3
and B
3
−Y
3
are calculated with the formulas shown below.
The color image signals (i.e., the luminance signal Y
3
and the color difference signals R
3
−Y
3
and B
3
−Y
3
), which are made up of color image signal components corresponding to respective pixels and have been obtained from the signal processing circuit
231
, are digitized by the analog-to-digital converting circuit
232
. The thus obtained luminance signal Y
3
is stored in a luminance signal storage area of the ordinary image memory
233
. Also, the thus obtained color difference signals R
3
−Y
3
and B
3
−Y
3
are stored in color difference signal storage areas of the ordinary image memory
233
. In accordance with the display timing, the color image signals having been stored in the ordinary image memory
233
are subjected to the digital-to-analog conversion in the digital-to-analog converting circuit
234
and transformed by the ordinary image encoder
235
into predetermined video signals. The thus obtained video signals are fed from the ordinary image encoder
235
into a superimposer
241
. In the superimposer
241
, the color image signals are superimposed upon the pseudo color image signals, which are formed in the manner described later. The superimposed image signals are fed into the monitor
170
.
How the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, operates when a fluorescence image is to be displayed will be described hereinbelow.
When a fluorescence image is to be displayed, the electric power source
215
for the GaN type of semiconductor laser
214
is driven in accordance with a control signal fed from the controller
250
, and the excitation light L
7
having a wavelength of 410 nm is produced by the GaN type of semiconductor laser
214
. The excitation light L
7
passes through a lens
216
and impinges upon the excitation light guide
201
b
. The excitation light L
7
is guided through the excitation light guide
201
b
to the leading end of the endoscope
200
, passes through the illuminating lens
203
, and is irradiated to the measuring site
20
.
When the measuring site
20
is exposed to the excitation light L
7
, fluorescence L
8
is produced from the measuring site
20
. The fluorescence L
8
is converged by the converging lens
204
, passes through the excitation light cut-off filter
208
, and is then reflected by the prism
207
. The fluorescence L
8
then passes through the mosaic filter
205
and is received by the CCD image sensor
206
.
The timings, with which the imaging of the ordinary image with irradiation of the white light L
5
and the imaging of the fluorescence image with irradiation of the excitation light L
7
are performed, are performed in accordance with a timing chart illustrated in FIG.
9
. As illustrated in
FIG. 9
, the operation for irradiating the white light L
5
and exposing the CCD image sensor
206
to the ordinary image and the operation for irradiating the excitation light L
7
and exposing the CCD image sensor
206
to the fluorescence image are performed alternately every {fraction (1/30)} second. In cases where the ordinary image is detected, the output signals of the CCD image sensor
206
are fed into the signal processing circuit
231
. In cases where the fluorescence image is detected, the output signals of the CCD image sensor
206
are fed into the signal processing circuit
221
.
Therefore, each of the ordinary image and the fluorescence image is acquired every {fraction (1/15)} second, and an ordinary image
40
and a fluorescence image
41
are displayed on the monitor
170
as dynamic images, which are updated every {fraction (1/15)} second. The operation timings described above are controlled by the controller
250
.
In the process circuit
226
of the signal processing circuit
221
, the processes are performed on the signals having been obtained from the CCD image sensor
206
. Thereafter, in the complementary color-to-primary color matrix operation circuit
227
, a signal intensity B
4
of the fluorescence components of the fluorescence L
8
, which fluorescence components have wavelengths falling within the blue wavelength region, and a signal intensity R
4
of the fluorescence components of the fluorescence L
8
, which fluorescence components have wavelengths falling within the red wavelength region, are calculated for each pixel in the manner described below. Specifically, matrix operations with Formula (5) shown below are performed by utilizing a signal intensity Ye
4
of the fluorescence components, which have wavelengths falling within the yellow wavelength region (i.e., green+red), a signal intensity Cy
4
of the fluorescence components, which have wavelengths falling within the cyan wavelength region (i.e., blue+green), and a signal intensity W
4
of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region. Each of the matrix operations is performed by utilizing the signal intensities corresponding to pixels adjacent to each pixel.
More specifically, the calculations are made with the formula shown below.
R
4=
W
4−
Cy
4
B
4=
W
4−
Ye
4
Further, in the image signal matrix operation circuit
228
, a pseudo luminance signal Y
4
and pseudo color difference signals R
4
−Y
4
and B
4
−Y
4
, which act as the pseudo color image signals, are calculated with matrix operations represented by Formula (6) shown below.
Therefore, the pseudo luminance signal Y
4
and the pseudo color difference signals R
4
−Y
4
and B
4
−Y
4
are calculated with the formulas shown below.
Y
4=
a
3·
R
4+
a
4·
B
4
R
4−
Y
4=
b
3·
R
4+
b
4·
B
4
B
4−
Y
4=
c
3·
R
4+
c
4·
B
4
The pseudo color image signals (i.e., the pseudo luminance signal Y
4
and the pseudo color difference signals R
4
−Y
4
and B
4
−Y
4
), which are made up of color image signal components corresponding to respective pixels and have been obtained from the signal-processing circuit
221
, are digitized by the analog-to-digital converting circuit
222
. The thus obtained pseudo color image signals are stored in the fluorescence image memory
223
. In accordance with the display timing, the pseudo color image signals having been stored in the fluorescence image memory
223
are subjected to the digital-to-analog conversion in the digital-to-analog converting circuit
224
and transformed by the fluorescence image encoder
225
into predetermined signals. The thus obtained signals are fed from the fluorescence image encoder
225
into the superimposer
241
. In the superimposer
241
, the pseudo color image signals are superimposed upon the color image signals representing the ordinary image (i.e., the luminance signal Y
3
and the color difference signals R
3
−Y
3
and B
3
−Y
3
), which have been obtained from the ordinary image memory
232
. The superimposed image signals are fed into the monitor
170
.
The monitor
170
transforms the color image signals and the pseudo color image signals into display signals and reproduces an ordinary image
40
and a fluorescence image
41
from the display signals. The fluorescence image
41
is displayed with a pseudo color, such that the display color varies in accordance with the ratio between the signal intensity R
4
of the fluorescence components, which have wavelengths falling within the red wavelength region, and the signal intensity B
4
of the fluorescence components, which have wavelengths falling within the blue wavelength region. The tint of the pseudo color of the fluorescence image
41
is determined by the coefficients (a
3
, a
4
, b
3
, b
4
, c
3
, and c
4
) in the matrix operation formulas employed in the image signal matrix operation circuit
228
.
The coefficients described above should preferably be selected such that the difference between the display color for the fluorescence, which has been produced from the normal tissues, and the display color for the fluorescence, which has been produced from the diseased tissues, may be clear. For example, the pseudo color may be displayed by selecting the coefficients such that the fluorescence, which has been produced from the normal tissues, may be displayed in white, and the fluorescence, which has been produced from the diseased tissues, may be displayed in pink or in one of other colors. In such cases, the person, who sees the displayed image, is capable of easily recognizing the state of the diseased tissues.
As described above, with the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, the signal intensity W
4
of the entire measurement wavelength region, the signal intensity Ye
4
of the wavelength region of at least 510 nm, and the signal intensity Cy
4
of the wavelength region of at most 600 nm are detected from the fluorescence L
8
, which is produced from the measuring site
20
when the measuring site
20
is exposed to the excitation light L
7
. Also, the signal intensity B
4
of the blue wavelength region of at most 510 nm and the signal intensity R
4
of the wavelength region of at least 600 nm are calculated from the signal intensity W
4
, the signal intensity Ye
4
and the signal intensity Cy
4
. The display color in accordance with the ratio between the signal intensity B
4
and the signal intensity R
4
is displayed by the utilization of the additive color mixture process. Therefore, the efficiency, with which the fluorescence L
8
having been produced from the measuring site
20
is utilized, is capable of being enhanced. Accordingly, the same effects as those with the first embodiment are capable of being obtained. Further, in the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, the signal intensity R
4
of the red wavelength region, which signal intensity is comparatively weak and is apt to be affected by noise, is not detected by the CCD image sensor. Therefore, the adverse effects of noise are capable of being kept smaller, and the signal-to-noise ratio of the display image is capable of being kept higher than when the signal intensity R
4
is detected in the conventional apparatus for displaying a fluorescence image.
Furthermore, with the endoscope system, in which the second embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, the CCD image sensor for detecting the fluorescence image is utilized also as the CCD image sensor for detecting the ordinary image. Therefore, the production cost of the apparatus for displaying a fluorescence image is capable of being kept low.
In the first and second embodiments described above, the ratio between the signal intensities of the predetermined wavelength regions is displayed by the utilization of the additive color mixture process and is expressed as a change in tint of the display color. Alternatively, instead of the additive color mixture process being utilized, the detected signal intensities of the predetermined wavelength regions may be divided by each other, and the value obtained from the division may be displayed. As another alternative, the value obtained from the division may be compared with a reference value, which has been calculated previously from the fluorescence having been produced from the normal tissues and the fluorescence having been produced from the diseased tissues, and the results of the comparison may be displayed.
In such cases, instead of the pseudo luminance signal and the pseudo color difference signals being calculated from the signal intensities of the primary color signals in the complementary color-to-primary color matrix operation circuit of the signal processing circuit for the fluorescence image, the value obtained from the division of the signal intensities of the two primary color signals by each other may be calculated, and pseudo color image signals in accordance with the value obtained from the division may be formed. The pseudo color image signals may then be superimposed upon the color image signals representing the ordinary image.
An endoscope system, in which a third embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, will be described hereinbelow with reference to FIG.
10
. In
FIG. 10
, similar elements are numbered with the same reference numerals with respect to FIG.
6
.
FIG. 10
is a schematic view showing the endoscope system, in which the third embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed. In the endoscope system, in which the third embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, excitation light is irradiated to a measuring site in a living body. A fluorescence image of the measuring site is detected by a CCD image sensor, which is located at the leading end of the endoscope and is utilized also for detecting an ordinary image. In this manner, the detected fluorescence image is displayed as a color image on the monitor.
The endoscope system, in which the third embodiment of the apparatus for displaying fluorescence information in accordance with the present invention is employed, comprises the endoscope
200
to be inserted into a region of a patient, which region is considered as being a diseased part, and the illuminating unit
210
provided with the light sources for producing the white light L
5
, which is used when an ordinary image is to be displayed, and the excitation light L
7
, which is used when a fluorescence image is to be displayed. The endoscope system also comprises an image processing unit
300
for performing image processing for displaying a fluorescence image and an ordinary image. The endoscope system further comprises a superimposer
310
for superimposing the ordinary image and the fluorescence image one upon the other. The endoscope system still further comprises a controller
320
, which is connected to the respective units and the superimposer
310
and controls operation timings. The endoscope system also comprises the monitor
170
for displaying the ordinary image and the fluorescence image as the color images.
The image processing unit
300
comprises a signal processing circuit
301
for forming color image signals from a fluorescence image and an ordinary image, which have been detected by the CCD image sensor
206
. The image processing unit
300
also comprises an analog-to-digital converting circuit
302
for digitizing the color image signals, which have been obtained from the signal processing circuit
301
. The image processing unit
300
further comprises an image memory
303
for storing the digital color image signals, which have been obtained from the analog-to-digital converting circuit
302
. The image processing unit
300
still further comprises a digital-to-analog converting circuit
304
for performing digital-to-analog conversion on the color image signals, which have been received from the image memory
303
. The image processing unit
300
also comprises an encoder
305
for transforming the color image signals, which have been received from the digital-to-analog converting circuit
304
, into video signals.
The signal processing circuit
301
comprises an ordinary image process circuit
306
for performing the processes, such as double sampling, amplification, and clamping, on signals in cases where the ordinary image is detected by the CCD image sensor
206
. The signal processing circuit
301
also comprises a fluorescence image process circuit
307
for performing the processes on signals in cases where the fluorescence image is detected by the CCD image sensor
206
. The signal processing circuit
301
further comprises a complementary color-to-primary color matrix operation circuit
308
for calculating the signal intensities of the blue wavelength region, the green wavelength region, and the red wavelength region, from the signal intensity of the light components, which have passed through the yellow filters
205
a
,
205
a
, . . . , the signal intensity of the light components, which have passed through the cyan filters
205
b
,
205
b
, . . . , and the signal intensity of the light components, which have passed through the blank areas
205
c
,
205
c
, . . . . The signal processing circuit
301
further comprises an image signal matrix operation circuit
309
for forming the color image signals from the signal intensities having been calculated by the complementary color-to-primary color matrix operation circuit
308
.
How the endoscope system, in which the third embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, operates will be described hereinbelow. Firstly, how the endoscope system operates when an ordinary image is to be displayed will be described hereinbelow.
When an ordinary image is to be displayed, the electric power source
212
for the white light source
211
is driven in accordance with a control signal fed from the controller
320
, and the white light L
5
is produced by the white light source
211
and irradiated to the measuring site
20
. The reflected light L
6
of the white light L
5
passes through the mosaic filter
205
and is received by the CCD image sensor
206
.
In the ordinary image process circuit
306
of the signal processing circuit
301
, the processes are performed on the signals having been obtained from the CCD image sensor
206
. Thereafter, in the complementary color-to-primary color matrix operation circuit
308
, in the same manner as that in the complementary color-to-primary color matrix operation circuit
237
of the signal processing circuit
231
shown in
FIG. 6
, the signal intensity B
3
of the light components of the reflected light L
6
, which light components have wavelengths falling within the blue wavelength region, the signal intensity G
3
of the light components of the reflected light L
6
, which light components have wavelengths falling within the green wavelength region, and the signal intensity R
3
of the light components of the reflected light L
6
, which light components have wavelengths falling within the red wavelength region, are calculated for each pixel with the matrix operations by utilizing the signal intensity Ye
3
of the light components, which have wavelengths falling within the yellow wavelength region (i.e., green+red), the signal intensity Cy
3
of the light components, which have wavelengths falling within the cyan wavelength region (i.e., blue+green), and the signal intensity W
3
of the light components, which have wavelengths falling within the entire measurement wavelength region. Each of the matrix operations is performed by utilizing the signal intensities corresponding to pixels adjacent to each pixel. Further, in the image signal matrix operation circuit
309
, the matrix operations are performed by utilizing the signal intensities B
3
, G
3
, and R
3
of the three primary colors. In this manner, the luminance signal Y
3
and the color difference signals R
3
−Y
3
and B
3
−Y
3
, which act as the color image signals according to the NTSC method, are calculated.
The color image signals (i.e., the luminance signal Y
3
and the color difference signals R
3
−Y
3
and B
3
−Y
3
), which are made up of color image signal components corresponding to respective pixels and have been obtained from the signal processing circuit
301
, are digitized by the analog-to-digital converting circuit
302
. The thus obtained color image signals are stored in an ordinary image storage area of the image memory
303
. In accordance with the display timing, the color image signals, which represent the ordinary image and having been stored in the image memory
303
, are subjected to the digital-to-analog conversion in the digital-to-analog converting circuit
304
and transformed by the encoder
305
into predetermined video signals. The thus obtained video signals are fed from the encoder
305
into the superimposer
310
. In the superimposer
310
, the color image signals are superimposed upon the color image signals, which represent the fluorescence image and are formed in the manner described later. The superimposed image signals are fed into the monitor
170
.
How the endoscope system, in which the third embodiment of the apparatus for displaying a fluorescence image in accordance with the present invention is employed, operates when a fluorescence image is to be displayed will be described hereinbelow.
When a fluorescence image is to be displayed, the electric power source
215
for the GaN type of semiconductor laser
214
is driven in accordance with a control signal fed from the controller
320
, and the excitation light L
7
having a wavelength of 410 nm is produced by the GaN type of semiconductor laser
214
. The excitation light L
7
is irradiated to the measuring site
20
.
When the measuring site
20
is exposed to the excitation light L
7
, fluorescence L
8
is produced from the measuring site
20
. The fluorescence L
8
passes through the mosaic filter
205
and is received by the CCD image sensor
206
.
As in the second embodiment described above, the timings, with which the imaging of the ordinary image with irradiation of the white light L
5
and the imaging of the fluorescence image with irradiation of the excitation light L
7
are performed, are controlled by the controller
320
and performed in accordance with the timing chart illustrated in FIG.
9
. As illustrated in
FIG. 9
, the operation for irradiating the white light L
5
and exposing the CCD image sensor
206
to the ordinary image and the operation for irradiating the excitation light L
7
and exposing the CCD image sensor
206
to the fluorescence image are performed alternately every {fraction (1/30)} second. In accordance with control signals given by the controller
320
, the signals obtained from the detection of the ordinary image are fed into the ordinary image process circuit
306
, and the signals obtained from the detection of the fluorescence image are fed into the fluorescence image process circuit
307
.
Therefore, each of the ordinary image and the fluorescence image is acquired every {fraction (1/15)} second, and the ordinary image
40
and a fluorescence image
50
are displayed on the monitor
170
as dynamic images, which are updated every {fraction (1/15)} second.
In the fluorescence image process circuit
307
of the signal processing circuit
301
, the processes are performed on the signals having been obtained from the CCD image sensor
206
. Thereafter, as in cases where the ordinary image is detected, in the complementary color-to-primary color matrix operation circuit
308
, a signal intensity B
5
of the fluorescence components of the fluorescence L
8
, which fluorescence components have wavelengths falling within the blue wavelength region, a signal intensity G
5
of the fluorescence components of the fluorescence L
8
, which fluorescence components have wavelengths falling within the green wavelength region, and a signal intensity R
5
of the fluorescence components of the fluorescence L
8
, which fluorescence components have wavelengths falling within the red wavelength region, are calculated for each pixel with the matrix operations by utilizing a signal intensity Ye
5
of the fluorescence components, which have wavelengths falling within the yellow wavelength region, a signal intensity Cy
5
of the fluorescence components, which have wavelengths falling within the cyan wavelength region, and a signal intensity W
5
of the fluorescence components, which have wavelengths falling within the entire measurement wavelength region. Further, in the image signal matrix operation circuit
309
, the matrix operations according to the NTSC method are performed by utilizing the signal intensities B
5
, G
5
, and R
5
of the three primary colors. In this manner, a luminance signal Y
5
and color difference signals R
5
−Y
5
and B
5
−Y
5
, which act as the color image signals, are calculated.
The color image signals (i.e., the luminance signal Y
5
and the color difference signals R
5
−Y
5
and B
5
−Y
5
), which are made up of color image signal components corresponding to respective pixels and have been obtained from the signal processing circuit
301
, are digitized by the analog-to-digital converting circuit
302
. The thus obtained color image signals are stored in a fluorescence image storage area of the image memory
303
. In accordance with the display timing, the color image signals, which represent the fluorescence image and having been stored in the image memory
303
, are subjected to the digital-to-analog conversion in the digital-to-analog converting circuit
304
and transformed by the encoder
305
into predetermined signals. The thus obtained signals are fed from the encoder
305
into the superimposer
310
. In the superimposer
310
, the color image signals are superimposed upon the color image signals representing the ordinary image (i.e., the luminance signal Y
3
and the color difference signals R
3
−Y
3
and B
3
−Y
3
), which have been received from the image memory
303
. The superimposed image signals are fed into the monitor
170
.
The monitor
170
transforms the color image signals representing the ordinary image and the color image signals representing the fluorescence image and displays the ordinary image
40
and the fluorescence image
50
.
Therefore, in the fluorescence image
50
, as in the cases of the ordinary image
40
, the signal intensity B
5
of the wavelength region of 430 nm to 510 nm is displayed as the color signal B, the signal intensity G
5
of the wavelength region of 510 nm to 600 nm is displayed as the color signal G, and the signal intensity R
5
of the wavelength region of 600 nm to 700 nm is displayed as the color signal R. In this manner, the fluorescence image
50
is displayed as an ordinarily formed color image. Accordingly, the display color with respect to the fluorescence produced from the normal tissues is cyan, and the display color with respect to the fluorescence produced from the diseased tissues is a color close to white. Thus the same effects as those with the second embodiment shown in
FIG. 6
are capable of being obtained. Further, a fine difference between the signal intensities of wavelength regions of the fluorescence produced from the measuring site is capable of being displayed as a difference in tint.
In the third embodiment described above, as the coefficients in the matrix operations for transforming the three primary color signals B
5
, G
5
, and R
5
into the color image signals in the image signal matrix operation circuit
309
, the coefficients, which are utilized in ordinary matrix operations employed in the NTSC method, are employed. Alternatively, the coefficients in the matrix operations may be selected in different ways. In this manner, the tint corresponding to each signal intensity may be set arbitrarily.
In the endoscope systems described above, in which the embodiments of the apparatus for displaying a fluorescence image in accordance with the present invention are employed, the mosaic filter
123
, which is constituted of the yellow filters
124
a
,
124
a
, . . . and the blank areas
124
b
,
124
b
, . . . , or the mosaic filter
205
, which is constituted of the yellow filters
205
a
,
205
a
, . . . , the cyan filters
205
b
,
205
b
, . . . , and the blank areas
205
c
,
205
c
, . . . , is employed. Alternatively, as illustrated in
FIG. 11
, in a modification of the embodiments of the apparatus for displaying a fluorescence image in accordance with the present invention, in lieu of the mosaic filters described above, a mosaic filter may be employed, which is constituted of yellow filters for transmitting only light having wavelengths falling within a wavelength region (a) of at least 510 nm, cyan filters for transmitting only light having wavelengths falling within a wavelength region (b) of at most 600 nm, and magenta filters acting as band-pass filters for transmitting only light having wavelengths falling within a wavelength region (d) comprising a sub-region of at most 510 nm and a sub-region of at least 600 nm.
In the modification described above, wherein the blank areas for transmitting light having wavelengths falling within the entire measurement wavelength region are not provided, a signal intensity W′ of the entire measurement wavelength region may be calculated with the formula shown below.
W′=½(Ye′+Cy′+Mg′)
in which Ye′ represents the signal intensity of the light components having passed through the yellow filters, Cy′ represents the signal intensity of the light components having passed through the cyan filters, and Mg′ represents the signal intensity of the light components having passed through the magenta filters.
Therefore, a signal intensity B′ of the blue wavelength region, a signal intensity G′ of the green wavelength region, and a signal intensity R′ of the red wavelength region may be calculated with the formulas shown below.
Thereafter, pseudo color image signals and colorimage signals may be calculated from the thus calculated color signals, and a pseudo color image or a color image may thereby be displayed. In this manner, the same effects as those with the second or third embodiment described above are capable of being obtained.
Further, in the embodiments described above, the signal intensities of the respective wavelength regions are detected by use of the mosaic filter, which comprises a plurality of fine filter elements arrayed alternately in a two-dimensional plane. Alternatively, for example, a rotating filter, which comprises a plurality of filters larger than the CCD image sensor, may be located in front of the CCD image sensor. In such cases, the signal intensities of the respective wavelength regions are capable of being calculated successively. In such cases, since the signal intensity of a desired wavelength region is calculated from the signal intensities of the respective wavelength regions having been stored successively, the display image cannot be displayed on the real time mode. However, in such cases, the resolution is capable of being enhanced, and therefore a sharp display image is capable of being obtained as for a measuring site, at which little motion occurs.
In addition, all of the contents of Japanese Patent Application No. 11(1999)-366667 are incorporated into this specification by reference.
Claims
- 1. An apparatus for displaying a fluorescence image, comprising:i) excitation light irradiating means for irradiating excitation light to a measuring site in a living body, the excitation light causing the measuring site to produce fluorescence, ii) image information acquiring means for acquiring image information in accordance with a signal intensity of fluorescence components of the fluorescence having been produced from the measuring site exposed to the excitation light, which fluorescence components have wavelengths falling within at least one desired wavelength region, and iii) displaying means for displaying the acquired image information, wherein the image information acquiring means comprises: a) a complementary color filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a wavelength region acting as a complementary color with respect to the desired wavelength region, b) complementary color signal intensity detecting means for detecting a signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the complementary color filter, c) entire signal intensity detecting means for detecting a signal intensity of fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within an entire measurement wavelength region of the fluorescence, and d) signal intensity calculating means for calculating the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the desired wavelength region, from the signal intensity, which has been detected by the complementary color signal intensity detecting means, and the signal intensity, which has been detected by the entire signal intensity detecting means.
- 2. An apparatus as defined in claim 1 wherein the entire signal intensity detecting means comprises an all-pass filter for transmitting the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the entire measurement wavelength region of the fluorescence, andentire measurement signal intensity detecting means for detecting the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the all-pass filter.
- 3. An apparatus as defined in claim 2 wherein a plurality of complementary color filters and a plurality of all-pass filters are arrayed alternately on a two-dimensional plane so as to constitute a mosaic filter.
- 4. An apparatus for displaying a fluorescence image, comprising:i) excitation light irradiating means for irradiating excitation light to a measuring site in a living body, the excitation light causing the measuring site to produce fluorescence, ii) image information acquiring means for acquiring image information in accordance with a signal intensity of fluorescence components of the fluorescence having been produced from the measuring site exposed to the excitation light, which fluorescence components have wavelengths falling within at least one desired wavelength region selected from among a blue wavelength region, a green wavelength region, and a red wavelength region, and iii) displaying means for displaying the acquired image information, wherein the image information acquiring means comprises: a) a yellow filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a yellow wavelength region acting as a complementary color with respect to the blue wavelength region, b) a magenta filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a magenta wavelength region acting as a complementary color with respect to the green wavelength region, c) a cyan filter for transmitting only fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within a cyan wavelength region acting as a complementary color with respect to the red wavelength region, d) complementary color signal intensity detecting means for detecting a signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the yellow filter, a signal intensity of the fluorescence components of the fluorescence; which fluorescence components have passed through the magenta filter, and a signal intensity of the fluorescence components of the fluorescence, which fluorescence components have passed through the cyan filter, e) entire signal intensity calculating means for calculating a signal intensity of fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within an entire measurement wavelength region of the fluorescence, from the signal intensity of the fluorescence components having wavelengths falling within the yellow wavelength region, the signal intensity of the fluorescence components having wavelengths falling within the magenta wavelength region, and the signal intensity of the fluorescence components having wavelengths falling within the cyan wavelength region, which signal intensities have been detected by the complementary color signal intensity detecting means, and f) signal intensity calculating means for calculating the signal intensity of the fluorescence components of the fluorescence, which fluorescence components have wavelengths falling within the desired wavelength region, from the signal intensities, which have been detected by the complementary color signal intensity detecting means, and the signal intensity of the fluorescence components having wavelengths falling within the entire measurement wavelength region of the fluorescence, which signal intensity has been calculated by the entire signal intensity calculating means.
- 5. An apparatus as defined in claim 4 wherein a plurality of yellow filters, a plurality of magenta filters, and a plurality of cyan filters are arrayed alternately on a two-dimensional plane so as to constitute a mosaic filter.
Priority Claims (1)
Number |
Date |
Country |
Kind |
11-366667 |
Dec 1999 |
JP |
|
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
6070096 |
Hayashi |
May 2000 |
A |
6422994 |
Kaneko et al. |
Jul 2002 |
B1 |