Surgery – Endoscope – Having imaging and illumination means
Reexamination Certificate
2001-04-24
2004-04-06
Leubecker, John P. (Department: 3739)
Surgery
Endoscope
Having imaging and illumination means
C600S160000, C600S476000, C359S361000
Reexamination Certificate
active
06716162
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a fluorescent endoscope apparatus for photographing as an image the autofluorescent light emitted from a living-tissue subject, representing the state of the tissues of the living-tissue subject, upon irradiation thereof by stimulating light.
2. Description of the Related Art
Researchers have long been researching fluorescent endoscope apparatuses for use in detecting the extremely faint fluorescent light emitted from a living-tissue subject irradiated by stimulating light, which can then be analyzed to distinguish the change of state in tissues accompanying various diseases.
For example, in in-vitro cancer diagnosis studies employing autofluorescence, by use of stimulating light having several specified wavelengths of light from within the wide spectrum covering the 330-450 nm range, it has been shown that it is possible to distinguish between normal and diseased tissues using this technique.
When light having such short wavelengths, from within the range spanning from the UV to the visible spectra, is employed as stimulating light, fluorescent light is emitted from the optical element forming the stimulating light projecting portion when the stimulating light is propagated therethrough. Also, the shorter the wavelength of the stimulating light, the higher the strength of the fluorescent light emitted from the optical element. Because of this, there are cases in which a non-fluorescent material such as silica, etc., which emits less fluorescent light when the stimulating light is transmitted therethrough, is used for forming the optical element forming the stimulating light projecting portion.
However, it was found that when a non-fluorescent material such as silica is used to form the optical element as a measure to reduced the strength of the fluorescent light emitted therefrom, fluorescent light containing the same wavelengths of the autofluorescent light is also emitted from the photographing portion photographing the image formed by the autofluorescent light (hereinafter also referred to as an autofluorescent image Zj) emitted by a living-tissue subject that has been irradiated by stimulating light. That is to say, the light reflected from the living-tissue subject irradiated by stimulating light enters the photographing portion, and by entry of this reflected stimulating light into the photographing portion, the constituent material of the optical element propagating the autofluorescent light contained within the photographing portion (for example, the components contained in multi-component glass, or the organic material component contained in colored fiber, etc.) have been found to emit fluorescent light upon exposure to stimulating light. Therefore, the fluorescent light emitted from this optical element is mixed, as noise, with the autofluorescent light entering the photographing portion, and as a result, the are instances in which an autofluorescent image containing much noise is photographed.
For example, there are studies in which, using a fiber-optic endoscope, in which the autofluorescent light is propagated by an image fiber, the strength of the fluorescent light emitted by the objective lens and image fiber has been found to be 0.8-0.9 times the value of the autofluorescent light emitted from normal tissue of a living-tissue subject. Furthermore, there are studies in which, irradiated by the same strength of stimulating light, the autofluorescent light emitted by a diseased tissue that should be the object of observation, which is {fraction (1/10)} of that of normal tissue, becomes buried in the fluorescent light, which becomes noise, produced by a forementioned objective lens and image fiber, and the diseased tissue has been spuriously diagnosed as a negative portion.
In addition, the normal observation range of a fluorescent endoscope apparatus is from a close point at a distance of 5 mm from the forward end of the endoscope portion to a far-point at a distance of 55 mm from the forward end of the endoscope portion. When the autofluorescent light emitted from the live-tissue subject located 55 mm from the forward end of the endoscope portion, which has been irradiated by the stimulating light Le projected from the forward end of the endoscope portion, is received at the photographing portion after being propagated thereto through the optical element, a portion of the stimulating light projected from the forward end of the endoscope portion toward the living-tissue subject located at a distance of 5 mm away from the forward end of the endoscope portion is reflected, and when this reflected stimulating light Lf is propagated within the optical element, the fluorescent light emitted by the optical element, which becomes noise, is received by the photographing portion together with aforementioned autofluorescent light, and even under the condition of the lowest possible S/N ratio enabling observation (that is, the condition of the observational limit), it is desirable that the diseased tissue and the normal tissue can be clearly distinguished.
SUMMARY OF THE INVENTION
The present invention has been developed in consideration of the circumstances described above, and it is a primary objective of the present invention to provide a fluorescent endoscope apparatus in which the fluorescent light, which becomes noise, emitted from the photographic element propagating the autofluorescent light emitted from a living-tissue subject is reduced, and by use of which it is possible to clearly distinguish between normal and diseased tissues.
The fluorescent endoscope apparatus according to the present invention comprises a stimulating light projecting means for irradiating a living-tissue subject with stimulating light, and a photographing means formed of an optical element for transferring the autofluorescent light emitted from the live-subject tissue upon irradiation thereof by stimulating light and a photographing element for photographing the autofluorescent light transferred thereto by said optical element, wherein said optical element is constructed so that the relationship of the normal-tissue fluorescent light of a strength K, which is the strength of the autofluorescent light emitted from the normal tissue of the live-tissue subject that has been transferred through said optical element and received by the photographing element, to the optical-element fluorescent light of a strength B, which is the strength of the fluorescent light emitted by said optical element when the reflected stimulating light reflected from the living tissue subject upon irradiation thereof by stimulating light is propagated through said optical element, satisfies the condition expressed by the formula: K≧B×10
4
.
Note that normal-tissue fluorescent light of a strength K and optical-element fluorescent light of a strength B are measured values as described below.
As shown in
FIG. 1A
, the autofluorescent light Lj emitted by a living-tissue subject
1
, of which all regions are normal tissue, upon irradiation thereof by stimulating light Le is passed through an optical element
2
formed of a stimulating light cutoff filter
2
a
that cuts off substantially 100 percent of the stimulating light and a focusing optical system
2
b
, and is received by a photographing element
3
. On the other hand, the stimulating light reflected by living-tissue subject
1
upon irradiation thereof by stimulating light, reflected stimulating light Lh, is substantially 100 percent cutoff by cutoff filter
2
a
before entering focusing optical system
2
b
. At this point, the unit per area strength of autofluorescent light Lj received by photographing element
3
is strength K.
As shown in
FIG. 1B
, the positions of the stimulating light cutoff filter
2
a
and the focusing optical system
2
b
forming optical element
2
are switched and stimulating light cutoff filter
2
a
is disposed between photographing element
3
and focusing optical system
2
b
, and when the aforementioned living-tissue subject
Fuji Photo Film Co. , Ltd.
Leubecker John P.
Sughrue & Mion, PLLC
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