Endoscope system

Surgery – Endoscope – Having imaging and illumination means

Reexamination Certificate

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C600S109000, C600S178000

Reexamination Certificate

active

06527708

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an endoscope system capable of capturing in vivo normal light images and fluorescent light images of a surface of an object, and OCT (optical coherence tomography) images of the object.
Endoscope systems used for observing inside a body cavity of a patient have been conventionally known. An example of conventional endoscope systems includes an endoscope to be inserted in the body cavity of the patient, and an external device connected to the endoscope. The external device includes a light source and an image processor.
The endoscope includes an illuminating optical system, which is connected to:
the light source of the external device, the illuminating optical system emitting light toward an object to be observed for illuminating the same;
an objective optical system for forming an object image; and
a CCD (Charge Coupled Device), which is arranged at an image plane of the objective optical system and is connected to the image processor of the external device.
At the distal end of the endoscope, an instrument outlet, from which various treatment instruments such as a forceps are to be protruded, is defined.
An operator of the endoscope system inserts the endoscope inside the body cavity of the patient, and illuminates paries of the cavity with the light emitted through the illuminating optical system. An image of the paries is formed by an objective optical system. The CCD converts the thus formed image (optical image) into an electrical signal (i.e., electrical image) and transmits the signal to the image processor included in the external device.
The external device processes the received image signal representing the image of the paries of the body cavity, and displays the image on a monitor. Thus, the operator is capable of observing the image of the paries of the body cavity displayed on the monitor.
If the operator determines that there is a portion which might be cancered or tumorous, the operator collects the biotissues at the portion using forceps or a biopsy needle protruded from the instrument outlet. The thus obtained biotissues are subjected to a pathological examination, based on the results of which a diagnosis is made.
In the conventional endoscope as described above, the displayed image shows only the surface of the paries of the body cavity. In order to know the condition of the tissues beneath the surface of the paries, biopsy is required. In particular, in order to detect cancer in its earliest form or relatively small tumors, the biopsy is indispensable. However, pathologic investigation of the biotissues obtained by the biopsy generally takes time, and therefore, the diagnosis also takes time.
Further, in view of the burden to the patient, the biopsy is to be done for only a limited portion by a limited amount of time. However, there is a possibility that portions other than those identified by the operator are diseased. Thus, unless the biopsy is done with respect to the diseased area, the accurate diagnosis cannot be expected.
Incidentally, a method for obtaining tomogram of biotissues utilizing a combination of a low-coherent light source such as a superluminescent diode (SLD) and a Michelson interferometer has been developed. Such a method is known as an OCT (Optical Coherent Tomography) system, an example of which is described in U.S. Pat. No. 5,321,501, the teachings of which are incorporated herein by reference.
For one solution of the afore-mentioned problem, an imaging system including a probe of the OCT has been known. Such a system is described in “In vivo endoscopic OCT imaging of precancer and cancer states of human mucosa”, by A. M. Sergeev et al., Dec. 22, 1997, vol. 1, No. 13 of OPTICS EXPRESS pp. 432-440, teaching of which is incorporated herein by reference.
In the above OCT system, however, a tomogram for a relatively wide area cannot be obtained at one time. Therefore, an operator of the system designates a portion, which might be diseased, and the OCT imaging is performed with respect to the designated portion. If the OCT system is incorporated in an endoscope system, the operator inserts the endoscope in the body cavity for normal observation, identifies a portion which might be diseased, and then performs the OCT imaging with respect to the identified portion.
FIG. 6
shows an example of a conventional OCT imaging system for an endoscope. In
FIG. 6
, a distal end portion
7
of the endoscope is shown. The distal end portion
7
has a substantially cylindrical shape, and on the tip end surface, an illumination window
71
, an observation window
72
and an instrument outlet opening
73
are formed. Inside the endoscope, although not shown, an illuminating optical system for directing a visible light beam is provided. Further, the endoscope is provided with an objective optical system (not shown) for receiving light from an object (e.g., a surface of the paries which is considered to be diseased) and forming an object image on an image receiving surface of a CCD (Charge Coupled Device), not shown.
The illumination optical system emits visible light through the illumination window
71
toward the object. The light reflected by the object enters the objective lens system through the observation window
72
. Then, an image of the object is formed on the image receiving surface of the CCD. The CCD then outputs an image signal, which is processed and displayed on a monitor
8
as a normal image.
Separate from the endoscope, an OCT apparatus having the SLD and a Michelson interferometer is provided. The interferometer Is provided with a measuring optical system and a reference optical system. The measuring optical system includes a fiber probe
9
, which is inserted through the endoscope, and the tip thereof is protruded from the instrument outlet
73
of the distal end portion
7
of the endoscope. The OCT apparatus is also connected to the monitor
8
, and an OCT image of a portion facing the tip end of the fiber probe
9
is displayed on the monitor
8
.
When in use, the operator inserts the endoscope inside the body cavity of the patient, and observes the normal image of the paries. If a portion which might be diseased is found, the operator makes the fiber probe
9
protrude from the instrument outlet
73
to confront with the portion in question. Then, the OCT apparatus is operated to capture a tomogram of the portion in question, and displays the same on the monitor
8
.
The monitor
8
is capable of selectively displaying the normal image and the OCT image in accordance with operation of switches and/or keyboard
6
. In
FIG. 6
, the monitor
8
displaying the normal image and the monitor
8
displaying the OCT image are drawn in order to show both conditions. Actually, however, the endoscope system is provided with only one monitor
8
, and one of the normal image and the OCT image is displayed on the monitor
8
. The operator makes diagnosis in accordance with thus displayed images.
According to the conventional endoscope system described above, the fiber probe
9
of the OCT apparatus protrudes from the instrument outlet
73
. The fiber probe
9
is located within a field of view of the objective optical system. Therefore, in the normal image displayed on the monitor
8
, the fiber probe
9
appears and forms a dead angle. The dead angle disturbs the observation of the normal image, which prevents the operator from recognizing positional relationship between the normal image and the OCT image.
In order to avoid such a problem, the objective optical system for the normal image and the tip of the measuring optical system of the OCT apparatus can be Integrated to a single optical system. In such a case, however, it becomes generally necessary to split optical paths of the normal image and the OCT image utilizing a half mirror, a dichroic mirror and the like. In such a configuration, the light amount is decreased when the light incident from the object is split, which deteriorates quality of the images.
SUMMARY OF THE INVENTION
In view of the above problems, it is an objec

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