Patent Publication Number: US-2023157623-A1

Title: Examination device, endoscope system, and examination method

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of PCT/JP2020/027360 filed on Jul. 14, 2020, the entire contents of which are incorporated herein by this reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an examination device, an endoscope system, and an examination method that effectively support swallowing videoendoscopy. 
     2. Description of the Related Art 
     A nasal endoscope inserted into the nose has been used to examine dysphagia. Dysphagia is a disorder that occurs in a series of processes in which food is sent from the mouth to the esophagus, and causes aspiration pneumonia or the like in which food enters the trachea and causes inflammation. 
     In the swallowing videoendoscopy, a series of swallowing images is picked up after putting food for examination in the mouth using a nasal endoscope, and the picked-up images are used to determine dysphagia. 
     However, a swallowing reflex is an action in a moment that makes diagnosis of a disorder level relatively difficult. For this reason, it is recommended that a system for performing swallowing videoendoscopy be provided with a recording and playback function. When diagnosis by normal playback of a recorded movie is difficult, the diagnosis can be made with slow playback or frame-by-frame playback. 
     In Japanese Patent Application Laid-Open Publication No. 2011-232715, a technique is proposed for accurately detecting an abnormal area from an intraluminal image by creating a closed region based on gradient information on each pixel based on a pixel value of the intraluminal image and detecting the abnormal area from inside the closed region. In Japanese Patent Application Laid-Open Publication No. 2013-111125, a technique is proposed for properly detecting an abnormal area by detecting an abnormal candidate area and a tubular area from an intraluminal image of a subject, and distinguishing the abnormal area from blood vessels based on a determination result of whether the abnormal candidate area and the tubular area are connected by an area having a color similar to that of the tubular area. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present invention, an examination device includes a processor, and the processor detects, in swallowing videoendoscopy in which an inflow object is given to a subject and a swallowing action is observed, at least two timings among a swallowing instruction timing at which a swallowing instruction is given, an inflow timing of the inflow object into the pharynx during the swallowing action, and a swallowing reflex triggering timing in the subject. 
     According to another aspect of the present invention, an endoscope system includes an endoscope, in swallowing videoendoscopy in which an inflow object is given to a subject and a swallowing action is observed, configured to be inserted into the subject, pick up images of the pharynx, and output the images picked up, a microphone configured to collect a voice of an operator, and a processor, in which the processor detects a swallowing instruction timing at which the operator instructs swallowing based on the voice from the microphone, and detects an inflow timing of the inflow object into the pharynx during the swallowing action and a swallowing reflex triggering timing in the subject based on the images picked up, and determines dysphagia of the subject based on information on at least two timings detected. 
     According to an aspect of the present invention, an examination method includes detecting, in swallowing videoendoscopy in which an inflow object is given to a subject and a swallowing action is observed, at least two timings among a swallowing instruction timing instructed to swallow by an operator, an inflow timing of the inflow object into the pharynx during the swallowing action, and a swallowing reflex triggering timing in the subject. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram illustrating a system for swallowing videoendoscopy according to a first embodiment of the present invention. 
         FIG.  2    is an explanatory diagram illustrating a mechanism of swallowing. 
         FIG.  3    is an explanatory diagram illustrating the mechanism of the swallowing. 
         FIG.  4    is an explanatory diagram illustrating the mechanism of the swallowing. 
         FIG.  5    is an explanatory diagram for explaining a general method for confirming a swallowing action in swallowing videoendoscopy. 
         FIG.  6    is an explanatory diagram for explaining the swallowing videoendoscopy. 
         FIG.  7    is an explanatory diagram for explaining a normal swallowing action. 
         FIG.  8    is an explanatory diagram for explaining detection of endoscope insertion. 
         FIG.  9    is an explanatory diagram for explaining inflow detection of an inflow object  8 . 
         FIG.  10    is an explanatory diagram for explaining detection of a swallowing reflex in a subject. 
         FIG.  11    is an explanatory diagram illustrating a pharyngeal swallowing disorder in a manner similar to that in  FIGS.  6  and  7   . 
         FIG.  12    is an explanatory diagram illustrating a method for determining a disorder level. 
         FIG.  13    is an explanatory diagram illustrating setting of a disorder level determination reference. 
         FIG.  14    is an explanatory diagram for explaining a process of determining a pharyngeal swallowing disorder in a process of determining dysphagia by a disorder determination circuit  30 . 
         FIG.  15    is an explanatory diagram illustrating a swallowing reflex disorder in the manner similar to that in  FIGS.  6  and  7   . 
         FIG.  16    is an explanatory diagram for explaining a process of determining a swallowing reflex disorder in the process of determining dysphagia by the disorder determination circuit  30 . 
         FIG.  17    is an explanatory diagram illustrating an inflow object residual disorder in the manner similar to that in  FIGS.  6  and  7   . 
         FIG.  18    is an explanatory diagram for explaining a process of determining the inflow object residual disorder in the process of determining dysphagia by the disorder determination circuit  30 . 
         FIG.  19    is a flowchart for explaining operation of a main circuit  21 . 
         FIG.  20    is a flowchart for explaining the operation of the main circuit  21 . 
         FIG.  21    is a diagram illustrating a work flow of the swallowing videoendoscopy and swallowing actions and endoscopic images (picked-up images) in a normal subject who has not developed dysphagia. 
         FIG.  22    is a block diagram illustrating another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
     First Embodiment 
       FIG.  1    is a block diagram illustrating a system for swallowing videoendoscopy according to a first embodiment of the present invention. In the present embodiment, based on information such as image information acquired during an examination, at least one of the following can be detected: a timing at which a doctor instructs swallowing, a timing at which an inflow object flows into the pharynx, and a swallowing reflex triggering timing in a subject. Then, based on a time relationship between the timings, diagnostic results such as a pharyngeal swallowing disorder, a swallowing reflex disorder, and an inflow object residual disorder can be obtained. 
       FIGS.  2  to  7    are explanatory diagrams for explaining normal swallowing actions.  FIGS.  2  to  4    illustrate a mechanism of swallowing.  FIG.  2    illustrates an oral phase,  FIG.  3    illustrates a pharyngeal phase, and  FIG.  4    illustrates an esophageal phase. 
       FIG.  2    illustrates the oral phase in which a bolus  9  (hatched area) is held in the oral cavity. The tongue  1  rises upward and the soft palate  3  lowers downward to separate the oral cavity from the pharynx  2  and hold the bolus  9  in the mouth so that the bolus  9  can be chewed and swallowed as necessary. In this state, the bolus  9  does not flow into the esophagus  6 , and the epiglottis  4  is raised to open the airway  5 . 
     When chewing is completed, a movement of the tongue  1  and contraction of the pharynx  2  feed the bolus  9  from the oral cavity into the esophagus  6 .  FIG.  3    illustrates the pharyngeal phase. Broken lines in  FIG.  3    illustrate states of the tongue  1 , the soft palate  3 , and the epiglottis  4  during the oral phase. During the pharyngeal phase, the tongue  1 , the soft palate  3 , and the epiglottis  4  change as indicated by arrows, whereby the bolus  9  is fed into the esophagus  6 . In the case above, the epiglottis  4  is lowered (closed) to occlude the airway  5  and prevent the bolus  9  from entering the airway  5 . 
       FIG.  4    illustrates the esophageal phase in which the bolus  9  flows into the esophagus  6 . When the bolus  9  flows into the esophagus  6 , the epiglottis  4  rises and returns to an original position thereof (opens), thereby connecting the airway  5  to the oral cavity and the nasal cavity, and allowing breathing. Broken lines in  FIG.  4    illustrate states of the soft palate  3  and the epiglottis  4  during the pharyngeal phase. During the esophageal phase, the soft palate  3  and the epiglottis  4  change as indicated by arrows, thereby opening the airway  5 . Dysphagia is an abnormality that occurs in any of the swallowing actions illustrated in  FIGS.  2  to  4   . 
       FIG.  5    is an explanatory diagram for explaining a typical method for confirming the swallowing action in swallowing videoendoscopy. The upper part of  FIG.  5    illustrates an endoscope  11  inserted into the nasal cavity for the swallowing videoendoscopy. 
     As will be described later, the endoscope  11  is provided with an image pickup apparatus (not illustrated) at a distal end of an elongated and flexible insertion portion. During the examination, a distal end portion of the endoscope  11  is stopped at an upper end of the pharynx  2  and positioned so that an optical axis of an image pickup device at the distal end faces the esophagus  6  side. With the endoscope  11 , it is possible to observe the pharynx  2 , the esophagus  6 , the food for examination flowing from the pharynx  2  to the esophagus  6 , the airway  5 , a movement of the epiglottis  4  that occludes the airway  5 , and the like. 
     The lower part of  FIG.  5    illustrates an image acquired by the endoscope  11 . In the example in  FIG.  5   , the picked-up image shows an opening of the airway  5  in the center of the image, the epiglottis  4  in an open state below the airway  5 , and the esophagus  6  in an occluded state above and to the left and right of the airway  5 . That is,  FIG.  5    illustrates an image before the bolus  9  flows into the pharynx  2 . 
     By using the endoscope  11  to acquire images in the oral phase, the pharyngeal phase, and the esophageal phase and observing states of swallowing from the acquired images, an operator can diagnose dysphagia. In the present embodiment, by detecting various kinds of timings using information such as image information, thereby enabling effective diagnostic support for dysphagia. 
       FIG.  6    is an explanatory diagram illustrating the swallowing videoendoscopy, specifically, changes in the actions of an operator and a subject (operator actions and subject actions) during the normal swallowing action and endoscopic images acquired at corresponding times, with time on the horizontal axis.  FIG.  7    is an explanatory diagram illustrating a timing at which the doctor instructs swallowing (hereinafter referred to as “swallowing instruction timing”), a timing at which the inflow object flows into the pharynx (hereinafter referred to as “inflow timing”), and a triggering timing of a swallowing reflex in the subject (hereinafter referred to as “swallowing reflex triggering timing”) during the normal swallowing action, with a time axis that matches the time axis of  FIG.  6   . 
     A timing t 0  in  FIG.  6    illustrates a state in which the distal end portion of the inserted endoscope  11 , which is indicated by a thick line, is stopped at a position at which the pharynx  2  can be observed at the upper end of the pharynx  2  (hereinafter referred to as “examination position”). When the examination is started, the operator puts an inflow object  8  (food for examination in  FIG.  6   ) indicated by hatched lines into the subject&#39;s mouth, and instructs the subject to hold the inflow object  8  in the oral cavity. In  FIG.  6   , a column of the subject action in the oral phase illustrates the subject holding the inflow object  8  in the oral cavity. In this state, as illustrated in the endoscopic image in  FIG.  6   , the airway  5 , the esophagus  6 , and the epiglottis  4  that does not cover the airway  5  are observed. 
     A timing t 1  in  FIG.  6    indicates a swallowing instruction timing at which the operator instructs the swallowing of the inflow object  8 . When the operator gives a swallowing instruction at the swallowing instruction timing t 1 , the subject swallows the inflow object  8  into the esophagus  6  by a series of actions of the tongue  1 , the pharynx  2 , the soft palate  3 , and the epiglottis  4  as described above. In  FIG.  6   , a column of the subject action in the pharyngeal phase and the esophageal phase illustrates the actions of the subject moving the inflow object  8  from the oral cavity to the pharynx  2  and then flows the inflow object  8  into the esophagus  6 . 
     According to the series of swallowing actions of the subject, the images picked up by the endoscope  11  vary as illustrated in  FIG.  6   . The normal swallowing action is performed in a very short time of approximately 0.5 seconds in total, so accurate diagnosis may be difficult for an unskilled person. In the present embodiment, in order to enable a quantitative diagnosis of dysphagia based on more objective facts, the series of swallowing actions swallowing an inflow object such as food for examination from the mouth into the esophagus  6  is determined at three timings. That is, in addition to the swallowing instruction timing t 1 , a timing at which the inflow object flows into the pharynx  2  is defined as an inflow timing t 2 , and a timing at which the epiglottis  4  closes to occlude the airway  5  and the esophagus  6  opens (swallowing reflex is triggered) is defined as a swallowing reflex triggering timing t 3 . 
     As illustrated in  FIG.  6   , at the inflow timing t 2 , the inflow object  8  (hatched portion) appears in the pharynx  2  in the endoscopic image. At the swallowing reflex triggering timing t 3 , due to the contraction of the pharynx  2  and the action of the epiglottis  4 , the living tissue approaches or comes into close contact with the distal end portion of the endoscope  11 , resulting in a white-out image in which the entire endoscopic image is white, as will be described later. The endoscope acquires approximately 10 to 20 frames of white-out images, and then again acquires images showing a contour of the pharynx  2 . 
     A timing t 4  in  FIG.  6    is a swallowing completion timing at which the swallowing reflex ends and movement of the inflow object into the esophagus  6  is completed. After the swallowing completion timing t 4 , the operator can confirm the inflow object residual disorder by checking whether the inflow object  8  remains in the pharynx  2 . In  FIG.  6   , the column of the subject action indicates that the swallowing action is completed after the swallowing completion timing t 4 . In the endoscopic image after the swallowing completion timing t 4 , the inflow object  8  does not remain in the epiglottis  4 , the airway  5 , and the esophagus  6 . 
       FIG.  7    shows timing charts for two examples in which the swallowing action is normal, in order to outline a method for determining dysphagia according to the present embodiment. In the present embodiment, the pharyngeal swallowing disorder, the swallowing reflex disorder, and the inflow object residual disorder can be determined based on the swallowing instruction timing t 1 , the inflow timing t 2 , and the swallowing reflex triggering timing t 3 . 
     Timings indicated by solid rectangles in  FIG.  7    indicate the timings of the insertion of the endoscope  11 , the instruction for swallowing, the inflow of the inflow object  8 , and the triggering of the swallowing reflex, respectively. As described with reference to  FIG.  6   , the timing t 0  in  FIG.  7    is the timing at which the examination is started and the subject holds the inflow object  8  in the oral cavity. At the swallowing instruction timing t 1 , the operator instructs the subject to swallow the inflow object  8 . 
     The pharyngeal swallowing disorder is a disorder in which the subject cannot normally hold the inflow object  8  in the oral cavity. A disorder in which the inflow object  8  cannot be held in the oral cavity and flows into the pharynx too early is referred to as “premature spillage into the pharynx”, whereas a disorder in which the inflow object  8  flows into the pharynx is too late is referred to as “delayed pharyngeal swallow”. Both disorders are the pharyngeal swallowing disorders due to muscle weakness of the tongue  1  or the like. 
     In  FIG.  7   , by comparing a period from the swallowing instruction timing t 1  to the inflow timing t 2  with a predetermined threshold value, the pharyngeal swallowing disorder can be determined. 
     The swallowing reflex disorder is a disorder in which the swallowing reflex is not triggered at an appropriate timing. A disorder in which the swallowing reflex occurs later than an appropriate timing is referred to as “delayed swallowing reflex”, whereas a disorder in which the swallowing reflex occurs earlier than the appropriate timing is referred to as “premature swallowing reflex”. The swallowing reflex is an involuntary reflex, and the swallowing reflex disorder occurs due to decreased sensation or the like. 
     In the upper part of  FIG.  7   , by comparing a period from the inflow timing t 2  to the swallowing reflex triggering timing t 3  with a predetermined threshold value, the swallowing reflex disorder can be determined. 
     The inflow object residual disorder is a disorder in which food or drink remains in the pharynx or trachea upon completion of swallowing (inflow object residue), and is caused by a weakening of the ability to close the throat and swallow. 
     Even when the swallowing action is normal, the inflow timing t 2  and the swallowing reflex triggering timing t 3  may be very close to each other, or the swallowing reflex triggering timing t 3  may precede the inflow timing t 2 . In the case above, the inflow of the inflow object  8  into the pharynx  2  at the inflow timing t 2  may not be confirmed by observation using the picked-up image due to the white-out images at the swallowing reflex triggering timing t 3 . 
       FIG.  7    illustrates an example of the case, in which the inflow timing t 2  is not detected. Even in the case above, by comparing a period from the swallowing instruction timing t 1  to the swallowing reflex triggering timing t 3  with a predetermined threshold value, the swallowing reflex disorder can be determined, and the pharyngeal swallowing disorder can also be estimated. 
     (Configuration) 
     As illustrated in  FIG.  1   , a system for the swallowing videoendoscopy mainly includes the endoscope  11 , a main circuit  21 , and a monitor  40 . The endoscope  11  is connected to the main circuit  21  by a cable (not illustrated) or wirelessly. The endoscope  11  includes an insertion portion  12  on a distal end side and an operation portion on a proximal end side. An image pickup apparatus  13  having an image pickup device such as a CCD or CMOS sensor is disposed at the distal end portion of the insertion portion  12 . A light guide  14  for transmitting illumination light for illuminating an object is disposed in the insertion portion  12 , and the illumination light transmitted through the light guide  14  is applied to the object via a lens (not illustrated) at the distal end of the insertion portion  12 . 
     Return light from the object is picked up on an image pickup surface of the image pickup apparatus  13  via an observation lens (not illustrated) at the distal end of the insertion portion  12 . The image pickup apparatus  13  obtains a picked-up image based on an optical image of the object by photoelectric conversion. The picked-up image from the image pickup apparatus  13  is supplied to the main circuit  21  via signal lines and cables disposed in the insertion portion  12  and the operation portion. 
     The main circuit  21  includes a control circuit  31 . The control circuit  31  can control individual units in the main circuit  21 , and the endoscope  11 . For example, the control circuit  31  may be configured by a processor using a central processing unit (CPU), a field programmable gate array (FPGA), or the like, may operate in accordance with a program stored in a memory (not illustrated) to control individual units, or may implement some or all of the functions by electronic circuits of hardware. 
     The control circuit  31  supplies clocks and various drive signals to the image pickup apparatus  13  of the endoscope  11  to drive the image pickup apparatus  13 . The main circuit  21  includes an illumination device  22  that supplies illumination light to the endoscope  11  and a developing circuit  23  that develops an image pickup signal from the image pickup apparatus  13  and outputs a video signal of an endoscopic image. The illumination device  22  includes a light source such as an LED, and generates illumination light. The illumination light is guided to the distal end portion of the endoscope  11  by the light guide  14  and is applied onto the object. Alternatively, the illumination device  22  and the light guide  14  may be omitted, and the object may be illuminated by an illumination device built into the endoscope  11 . 
     The developing circuit  23  obtains a video signal by developing the picked-up image from the image pickup apparatus  13 . For example, a so-called RAW image is inputted as a picked-up image from the image pickup apparatus  13 . The developing circuit  23  processes the RAW image for image display or the like based on the RAW image, based on various kinds of information such as information on the image size of the image pickup device of the image pickup apparatus  13 , information indicating whether an image pickup method is a frame sequential method or a simultaneous method, and information on the observation mode specified by the control circuit  31 . 
     The picked-up image (endoscopic image) processed by the developing circuit  23  is supplied to the monitor  40 . The monitor  40  displays the inputted endoscopic image. Thus, the picked-up image during the examination can be observed on the display screen of the monitor  40 . 
     (Timing Detection) 
     Further, the endoscopic image from the developing circuit  23  is also supplied to a timing detection circuit  24 . The timing detection circuit  24  includes a swallowing instruction detection circuit  25 , an endoscope insertion detection circuit  26 , an inflow detection circuit  27 , and a swallowing reflex detection circuit  28 . At least one circuit in the timing detection circuit  24  and a disorder determination circuit  30  to be described later may be configured by a processor using a CPU, an FPGA, or the like, may operate in accordance with a program stored in a memory (not illustrated) to control individual units, or may implement some or all of functions by electronic circuits of hardware. 
     The timing detection circuit  24  is also supplied with an output of a timer  32 . The timer  32  generates information about the current time or the time from the activation of the main circuit  21  or the image pickup apparatus  13  and outputs the information to individual circuits in the timing detection circuit  24 . The main circuit  21  may be provided with a microphone  33 . The microphone  33  collects ambient sound and outputs the sound to the individual circuits in the timing detection circuit  24 . For example, the microphone  33  may be used to capture the voice of the operator instructing swallowing and supply the captured voice to the swallowing instruction detection circuit  25 . Note that an input operation section such as a button (not illustrated) may be provided in the main circuit  21  or the endoscope  11 , which is operated to notify the timing detection circuit  24  of the swallowing instruction by the operator or the like. 
     The swallowing instruction detection circuit  25  detects the timing of the swallowing instruction by the operator based on an audio signal from the microphone  33  or the operation signal from the input operation section (not illustrated). For example, the swallowing instruction detection circuit  25  may detect the timing of the swallowing instruction by the operator by audio recognition processing on the inputted audio signal, or may detect the timing of the swallowing instruction by the operator by detecting an input of a predetermined audio waveform. 
     The swallowing instruction detection circuit  25  outputs a detection result of the swallowing instruction timing to a timing recording memory  29  together with time information from the timer  32 . The timing recording memory  29  is constituted of a predetermined recording medium and records various kinds of timing information (time information) detected by the individual circuits in the timing detection circuit  24 . 
     The endoscope insertion detection circuit  26  detects that the endoscope  11  has been inserted into the nasal cavity and the distal end portion thereof has reached the examination position, and records the detection timing of insertion (hereinafter referred to as “insertion detection timing”) in the timing recording memory  29  using the time information from the timer  32 . For example, the endoscope insertion detection circuit  26  may perform image analysis on the picked-up image from the developing circuit  23  and detect the insertion of the endoscope  11  based on the analysis result. 
       FIG.  8    is an explanatory diagram for explaining the detection of the endoscope insertion.  FIG.  8    illustrates images picked up by the image pickup apparatus  13 . Images P 1  and P 2  are images before the distal end portion of the endoscope  11  reaches the examination position, and an image P 3  is an image after the distal end portion of the endoscope  11  reaches the examination position. Note that the image P 1  is an image obtained when the distal end portion of the endoscope  11  is wiped with a cloth or the like before insertion of the endoscope  11 . The image P 3  is obtained by picking up an image of part of the pharynx  2  at the examination position, and typically is an image having many red components. On the other hand, the images P 1  and P 2  have fewer red components. 
     The endoscope insertion detection circuit  26  can detect that the endoscope  11  has been inserted into the nasal cavity and the distal end portion thereof has reached the examination position, for example, by determining the color of the picked-up image. For example, the endoscope insertion detection circuit  26  may detect that the distal end portion of the endoscope  11  has reached the examination position by comparing the number of pixels within a predetermined color space that includes a red hue in the image to a threshold value. After the endoscope insertion detection circuit  26  detects that the distal end portion of the endoscope  11  has reached the examination position, the endoscope insertion detection circuit  26  may record the timing of the detection in the timing recording memory  29  as the insertion detection timing. 
     The endoscope insertion detection circuit  26  may acquire the insertion detection timing based on an audio signal from the microphone  33  that collects the operator&#39;s speech or an operation signal from the input operation section (not illustrated). 
     The inflow detection circuit  27  detects that the inflow object  8  in the oral cavity of the subject has flowed into the pharynx  2 , and records the timing of the detection (inflow timing) in the timing recording memory  29 . For example, the inflow detection circuit  27  may perform image analysis on the picked-up image from the developing circuit  23  and may detect the inflow of the inflow object  8  based on the analysis result. 
       FIG.  9    is an explanatory diagram for explaining the inflow detection of the inflow object  8 .  FIG.  9    illustrates images picked up by the image pickup apparatus  13 . An image P 5  is an image before the inflow object  8  flows into the pharynx  2 , and an image P 6  is an image when the inflow object  8  has flowed into the pharynx  2 . The image P 5  and the image P 6  are substantially the same images except for the presence or absence of a portion (hatched portion) corresponding to the inflow object  8  in the image. The image P 5  as a whole has substantially the color of living tissue, that is, a reddish color. On the other hand, the image P 6  has a color influenced by the color of the inflow object  8  in a portion into which the inflow object  8  has flowed. 
       FIG.  9    illustrates an example in which the inflow object  8  is purple. For example, it is assumed that the (R, G, B) value of the average hue of a region P 5   a  of the image P 5  is ( 161 ,  102 ,  79 ) in the RGB color system, and the (R, G, B) value of the average hue of a region P 6   a  of the image P 6  at the same position as the region P 5   a  is ( 152 ,  73 ,  118 ) in the RGB color system. That is, in the case above, while the average color of the region P 5   a  is close to the red color of the living tissue, the average color of the region P 6   a  is close to the purple color of the inflow object  8 . Therefore, the region P 6   a  is considered to correspond to the portion into which the inflow object  8  has flowed. For example, the inflow detection circuit  27  may detect the inflow of the inflow object  8  according to whether an area of an image region having the color similar to the color of the inflow object  8  is larger than a threshold value. 
     Note that the color of the inflow object  8  is not limited to purple, and can be any color such as blue or white that can be easily distinguished from the color of the living tissue. Further, food or the like that meets the preference of the subject may be employed as the inflow object  8 . Even in the case above, when the color of the inflow object  8  is different from the color of the living tissue, the inflow of the inflow object  8  can be detected. 
     Even before the endoscope  11  is inserted into the nasal cavity, the image acquired by the image pickup apparatus  13  may be an image that includes many areas having the color similar to the color of the inflow object  8 . Thus, in order to distinguish between the image obtained by the inflow of the inflow object  8  and the image before the insertion of the endoscope  11 , the inflow detection circuit  27  may acquire the information on the insertion detection timing detected by the endoscope insertion detection circuit  26  from the timing recording memory  29  (not illustrated) and detect the inflow of the inflow object  8  by the image acquired after the insertion detection timing. 
     The swallowing reflex detection circuit  28  detects that the triggering of the swallowing reflex occurs in the subject, and records the timing of the detection (swallowing reflex triggering timing) in the timing recording memory  29 . For example, the swallowing reflex detection circuit  28  may perform image analysis on the picked-up image and detect the swallowing reflex based on the analysis result. 
       FIG.  10    is an explanatory diagram for explaining swallowing reflex detection in the subject.  FIG.  10    illustrates images picked up by the image pickup apparatus  13 . An image P 7  is an image before the triggering of the swallowing reflex occurs in the subject, and an image P 8  is an image when the triggering of the swallowing reflex has occurred in the subject. The image P 7  is an image in which a distance between the image pickup apparatus  13  and the pharynx  2  is appropriate, and the pharynx  2  is illuminated with an appropriate amount of light and is in focus, and clearly shows a state of the pharynx  2  before swallowing. On the other hand, the image P 8  is an image acquired when the living tissue is close to the image pickup apparatus  13  due to the swallowing reflex. 
     The control circuit  31  controls light adjustment of the illumination device  22  according to the brightness of the picked-up image. For example, the control circuit  31  increases the amount of illumination light when a distance from the distal end portion to the living tissue is long, and decreases the amount of illumination light when the distance from the distal end portion to the living tissue is short, thereby adjusting the brightness of the picked-up image to appropriate brightness. However, since a distance between the image pickup apparatus  13  and the living tissue becomes short in a very short time due to the swallowing reflex, the light adjustment control for reducing the amount of illumination light is not in time, and the picked-up images become white-out images. The image P 8  shows the white-out image. The image P 8  is clearly brighter than the image P 7 , thus, the swallowing reflex detection circuit  28  can determine that the white-out image has been acquired based on the average pixel value. 
     Alternatively, the swallowing reflex detection circuit  28  may detect that the white-out image has been acquired by filtering the inputted picked-up image. For example, the swallowing reflex detection circuit  28  may perform edge filtering on the inputted picked-up image. 
     Images P 9  and P 10  in  FIG.  10    are obtained by applying edge filtering to the images P 7  and P 8 , respectively. The image P 9  has many edge portions P 9   a . On the other hand, the image P 10  has no edge portions. When the swallowing reflex detection circuit  28  performs edge detection on the images P 9  and P 10  and determines that no edge portions are detected or the number of edge portions is equal to or less than a predetermined threshold number, the swallowing reflex detection circuit  28  may determine that the white-out image has been acquired, that is, the swallowing reflex has been detected. 
     Since the image pickup apparatus  13  acquires the white-out images due to the swallowing reflex, and then acquires normal luminance images again in a relatively short period of time, the swallowing reflex can be detected more reliably by the determination based on the edge detection by edge filtering than by the determination based on the luminance level of the white-out image. 
     Even before the endoscope  11  is inserted into the nasal cavity, the image acquired by the image pickup apparatus  13  may be a white-out image. Also, after the insertion detection timing, when the subject coughs or the like, the image pickup apparatus  13  and the living tissue come close to each other, and a white-out image may be acquired. Thus, in order to distinguish a white-out image due to the swallowing reflex from white-out images due to factors other than the swallowing reflex, the swallowing reflex detection circuit  28  may acquire information on the insertion detection timing detected by the endoscope insertion detection circuit  26 , information on the swallowing instruction timing, information on the inflow timing, and the like from the timing recording memory  29  (not illustrated), and detect the swallowing reflex by a white-out image acquired within a predetermined time after the insertion detection timing and the swallowing instruction timing or a white-out image acquired within a predetermined time after the inflow timing. 
     Although an example has been described in which the swallowing reflex detection circuit  28  detects the swallowing reflex based on whether the image pickup apparatus  13  has acquired a white-out image, other methods may be employed. When a high-speed camera is adopted as the image pickup apparatus  13 , the light adjustment control may also be faster and the white-out images may not be acquired. In the case above, the swallowing reflex detection circuit  28  may detect the swallowing reflex by image analysis of an image picked up by the image pickup apparatus  13 , which is the high-speed camera. 
     Although an example in which the swallowing reflex detection circuit  28  detects the swallowing reflex by image analysis has been described, a contact sensor (not illustrated) may be provided at the distal end portion of the endoscope  11  and the swallowing reflex may be detected using the output of the contact sensor. In the case above, the swallowing reflex detection circuit  28  may detect that the swallowing reflex has been triggered by the output of the contact sensor, which is generated by the living tissue coming into contact with the contact sensor due to the swallowing reflex. 
     Although an example in which each circuit in the timing detection circuit  24  records the timing information in the timing recording memory  29  using the time information from the timer  32  has been described, various kinds of timing information may be obtained using frame numbers in the picked-up images from the developing circuit  23  instead of the time information from the timer  32  and the obtained information may be recorded in the timing recording memory  29 . 
     Any of various types of recording media, such as semiconductor recording media and magnetic recording media, can be employed for the timing recording memory  29 . The timing recording memory  29  records various kinds of timing information from the timing detection circuit  24  and also outputs the recorded timing information to the disorder determination circuit  30  and an output circuit  34 . 
     The output circuit  34  is capable of outputting the various kinds of timing information from the timing recording memory  29  and determination information about dysphagia from the disorder determination circuit  30  to an external device. For example, the output circuit  34  may include a communication circuit (not illustrated) capable of communicating with the outside by wire or wirelessly. The communication circuit may be configured to enable communication such as wireless communication using a wireless LAN such as Wi-Fi (registered trademark) or Bluetooth (registered trademark), or wired communication using a LAN cable or USB cable. 
     Although the output circuit  34  has been described as being capable of outputting the various kinds of timing information from the timing recording memory  29 , the output circuit  34  may be configured to directly transmit the various kinds of timing information from the timing detection circuit  24  to an external device. 
     In addition to simply outputting the inputted various kinds of timing information, the output circuit  34  may also have a function of converting the timing information into display information for presenting to the operator or the like, converting the display information into a video signal that can be displayed on the monitor  40 , and outputting the video signal. 
     (Disorder Determination) 
     The disorder determination circuit  30  reads various kinds of timing information from the timing recording memory  29  and determines whether the subject has dysphagia based on the read timing information. The disorder determination circuit  30  may also be supplied with the picked-up image from the developing circuit  23  (not illustrated). The disorder determination circuit  30  may analyze the picked-up image from the developing circuit  23  and determine dysphagia using not only the timing information but also the image analysis result. 
     (Pharyngeal Swallowing Disorder Determination) 
       FIGS.  11  to  14    are explanatory diagrams for explaining a process of determining the pharyngeal swallowing disorder in the process of determining dysphagia by the disorder determination circuit  30 .  FIG.  11    illustrates a pharyngeal swallowing disorder in a manner similar to that in  FIGS.  6  and  7   .  FIG.  12    is the diagram for explaining a method for determining a disorder level,  FIG.  13    shows the setting of a disorder level determination reference, and  FIG.  14    illustrates a method for determining ease of swallowing the inflow object  8 . 
     A column of the subject action in the oral phase in  FIG.  11    illustrates a state in which a part  8   a  of the inflow object  8  held in the oral cavity by the subject flows into the pharynx  2 . The state is the premature spillage into the pharynx caused by muscle weakness of the subject or the like. The inflow detection circuit  27  can detect that the inflow object has flowed into the pharynx  2  by the color of a portion P 21   a  (hatched portion) in a picked-up image P 21  corresponding to the inflow object  8  in the case above. 
     When dysphagia does not occur, as illustrated in  FIG.  6   , the inflow object  8  flows into the pharynx  2  after the timing of the swallowing instruction by the operator. On the other hand, in the case of the premature spillage into the pharynx, as illustrated in  FIG.  11   , the swallowing instruction by the operator is given after the inflow timing at which the inflow object  8  flows into the pharynx  2 . 
     When the relationship between the swallowing instruction timing and the inflow timing read from the timing recording memory  29  is opposite to the normal state, that is, when the inflow timing is earlier than the swallowing instruction timing, the disorder determination circuit  30  can determine that the subject has the premature spillage into the pharynx in the pharyngeal swallowing disorder. 
     Further, from the relationship between the inflow timing and the swallowing instruction timing, the disorder determination circuit  30  can determine not only the premature spillage into the pharynx but also the delayed pharyngeal swallow in the pharyngeal swallowing disorder and can also determine the disorder level of the pharyngeal swallowing disorder. 
       FIG.  12    illustrates the insertion detection timing (endoscope insertion), the swallowing instruction timing (swallowing instruction), and the inflow timing of the inflow object such as food for examination (inflow of food for examination) by solid rectangle positions with time on the horizontal axis.  FIG.  12    illustrates a case of the premature spillage into the pharynx, in which the inflow timing is earlier than the swallowing instruction timing by a time t 11 , and a case of the delayed pharyngeal swallow, in which the inflow timing is later than the swallowing instruction timing by a time t 11 ′. In a normal case, the entire swallowing action takes approximately 0.5 seconds. Thus, for example, the disorder determination circuit  30  may determine that the pharyngeal swallowing disorder is severe when t 11  or t 11 ′ is approximately several tens of seconds, may determine that the pharyngeal swallowing disorder is moderate when t 11  or t 11 ′ is approximately several seconds, and may determine that the pharyngeal swallowing disorder is mild when t 11  or t 11 ′ is approximately one to two seconds. 
     The disorder determination circuit  30  includes a memory  30   a  that stores disorder level determination reference information that serves as a reference for determination of such a disorder level. The disorder determination circuit  30  may read the disorder level determination reference information from the memory  30   a  and determine the disorder level of the pharyngeal swallowing disorder by comparing information on determination reference time set in the disorder level determination reference information with a time difference between the swallowing instruction timing and the inflow timing. 
       FIG.  13    shows an example of the disorder level determination reference information. The example in  FIG.  13    includes the information on the determination reference time for determining severe, moderate, and mild for each of the pharyngeal swallowing disorder, the swallowing reflex disorder, and the inflow object residual disorder. In the example in  FIG.  13   , the determination reference time varies depending on the type of inflow object such as food for examination. Some inflow objects are prone to the premature spillage into the pharynx or the delayed pharyngeal swallow. Therefore, in order to more accurately determine the pharyngeal swallowing disorder, the determination reference time differs depending on the type of inflow object. 
       FIG.  14    illustrates a relationship between the type of inflow object and the ease of swallowing for determining the determination reference time. The left side of  FIG.  14    illustrates easy-to-swallow inflow objects, such as thickened water and jelly, which have the properties of being homogeneous, not breaking apart in the mouth, and not sticking to mucous membranes. The right side of  FIG.  14    illustrates difficult-to-swallow inflow objects, such as rice gruel and general food, which have the properties of being inhomogeneous, tending to break apart in the mouth, and tending to stick to mucous membranes. In the example shown in  FIG.  13   , the determination reference times are set by classifying the inflow objects into two types depending on whether the inflow objects are easy to swallow, but the inflow objects may be classified into three or more types. 
     In the example in  FIG.  13   , the determination reference time for the severe disorder is longer than the determination reference time for the moderate disorder, the determination reference time for the moderate disorder is longer than the determination reference time for the mild disorder, and these determination reference times have durations. In the example in  FIG.  13   , the determination reference times of approximately several tens of seconds, approximately several seconds, and approximately 1 to 2 seconds correspond to, for example, a time longer than 20 seconds, a time longer than 2 seconds and shorter than or equal to 20 seconds, and a time of 1 to 2 seconds, respectively. In the following description, the setting example above is referred to as a first setting of the determination reference time. 
     For example, assuming that the swallowing videoendoscopy is performed using an inflow object that is easy to swallow in the first setting of the determination reference time, when the t 11  or t 11 ′ in  FIG.  12    is 1.5 seconds, the disorder determination circuit  30  determines that the subject has a mild pharyngeal swallowing disorder, when the t 11  or t 11 ′ is 5 seconds, the disorder determination circuit  30  determines that the subject has a moderate pharyngeal swallowing disorder, and when the t 11  or t 11 ′ is 25 seconds, the disorder determination circuit  30  determines that the subject has a severe pharyngeal swallowing disorder. When the t 11  or t 11 ′ in  FIG.  12    is 0.5 seconds, the disorder determination circuit  30  determines that the pharyngeal swallowing disorder has not occurred because the pharyngeal swallowing is within the normal range. That is, when the time t 11  is shorter than the determination reference time for the mild disorder, the subject may be determined to be normal even when the inflow timing is earlier than the swallowing instruction timing. 
     The disorder determination circuit  30  is capable of updating the disorder level determination reference information recorded in the memory  30   a . For example, the operator or the like can give an instruction to the disorder determination circuit  30  using an input device (not illustrated) to update the information on the determination reference time and the information on the type of the inflow object in the disorder level determination reference information. Alternatively, the disorder determination circuit  30  may receive the disorder level determination reference information from an external device via a communication circuit (not illustrated). 
     The disorder level determination reference information in  FIG.  13    is applicable not only to the pharyngeal swallowing disorder but also to other types of dysphagia. Although the example in  FIG.  13    shows an example of setting a common determination reference time for all of the pharyngeal swallowing disorder, the swallowing reflex disorder, and the inflow object residual disorder, it is apparent that different determination reference times may be set for the different types of dysphagia. Although  FIG.  13    shows an example in which the determination reference time varies depending on the type of the inflow object, the determination reference time may vary depending on the age of the subject. Thus, the determination reference time can be set according to various factors. 
     (Swallowing Reflex Disorder Determination) 
       FIGS.  15  and  16    are explanatory diagrams for explaining a process of determining the swallowing reflex disorder in the process of determining dysphagia by the disorder determination circuit  30 .  FIG.  15    illustrates the swallowing reflex disorder in the manner similar to that in  FIGS.  6  and  7   .  FIG.  16    is the diagram for explaining a method for determining the disorder level. 
     A column of the subject action in the pharyngeal phase in  FIG.  16    illustrates a process in which the subject flows the inflow object  8  held in the oral cavity from the pharynx  2  to the esophagus  6 . In the example in  FIG.  16   , the time from the inflow of the inflow object  8  into the pharynx  2  to the triggering of the swallowing reflex is relatively long. The above is the delayed swallowing reflex caused by, for example, decreased sensation of the subject or the like. The swallowing reflex disorder can be determined by the time from the inflow timing when the inflow object  8  flows into the pharynx  2  to the swallowing reflex triggering timing or the time from the swallowing instruction timing when the operator instructs swallowing to the swallowing reflex triggering timing. 
     The swallowing instruction detection circuit  25  detects the swallowing instruction timing by the voice of the operator instructing swallowing or the operation of the swallowing instruction to the input operation section. The inflow detection circuit  27  detects the inflow timing based on the color of a portion P 31   a  (hatched portion) in a picked-up image P 31  corresponding to the inflow object  8 . The swallowing reflex detection circuit  28  detects the swallowing reflex triggering timing by determining that an image P 32  picked up by the image pickup apparatus  13  is a white-out image. 
     When dysphagia does not occur, as illustrated in  FIG.  6   , the swallowing reflex is triggered in a relatively short time from the timing of the swallowing instruction by the operator or the inflow timing of the inflow object  8 . On the other hand, in the delayed swallowing reflex, as illustrated in  FIG.  16   , the swallowing reflex is triggered a relatively long time after the swallowing instruction timing and the inflow timing. 
     When a time difference between the swallowing instruction timing or the inflow timing read from the timing recording memory  29  and the swallowing reflex triggering timing is longer than the determination reference time, the disorder determination circuit  30  can determine that the subject has the delayed swallowing reflex in the swallowing reflex disorder. 
       FIG.  16    illustrates the swallowing instruction timing, the inflow timing, and the swallowing reflex triggering timing by solid rectangle positions with time on the horizontal axis.  FIG.  16    illustrates a case of the delayed swallowing reflex, in which the swallowing reflex triggering timing is delayed by a time t 12  relative to the inflow timing. 
     The disorder determination circuit  30  may read the disorder level determination reference information from the memory  30   a  and determine the disorder level of the swallowing reflex disorder by comparing the information on the determination reference time set in the disorder level determination reference information with the time difference between the swallowing instruction timing or the inflow timing and the swallowing reflex triggering timing. 
     In  FIG.  13   , for example, assuming that the swallowing videoendoscopy is performed using an inflow object that is easy to swallow in the first setting of the determination reference time, when the t 12  in  FIG.  16    is 1.5 seconds, the disorder determination circuit  30  determines that the subject has a mild swallowing reflex disorder, when the t 12  is 5 seconds, the disorder determination circuit  30  determines that the subject has a moderate swallowing reflex disorder, and when the t 12  is 25 seconds, the disorder determination circuit  30  determines that the subject has a severe swallowing reflex disorder. When the t 12  in  FIG.  16    is 0.5 seconds, the disorder determination circuit  30  determines that the swallowing reflex disorder has not occurred because the swallowing reflex triggering is within a normal range. 
     In the example illustrated in  FIG.  16   , an example is described in which the determination is made based on the time difference between the inflow timing and the swallowing reflex triggering timing on the assumption that the inflow timing has been detected. However, when the inflow timing is not detected, the determination may be made based on the time difference between the swallowing instruction timing and the swallowing reflex triggering timing. 
     From the time difference between the swallowing instruction timing or the inflow timing and the swallowing reflex triggering timing, the disorder determination circuit  30  can determine not only the delayed swallowing reflex but also the premature swallowing reflex in the swallowing reflex disorder. In the case above, a range between a minimum time difference and a maximum time difference that can be determined to be normal is determined from the swallowing instruction timing or the inflow timing, and when the time difference is out of the range, the subject is determined to have the swallowing reflex disorder. When the time difference between the swallowing instruction timing or the inflow timing and the swallowing reflex triggering timing is shorter than the minimum time difference, the disorder determination circuit  30  determines the disorder level of the premature swallowing reflex according to the degree of the time difference. On the other hand, when the time difference between the swallowing instruction timing or the inflow timing and the swallowing reflex triggering timing is longer than the maximum time difference, the disorder determination circuit  30  determines the disorder level of the delayed swallowing reflex according to the degree of the time difference. 
     (Inflow Object Residual Disorder Determination) 
       FIGS.  17  and  18    are explanatory diagrams for explaining a process of determining the inflow object residual disorder in the process of determining dysphagia by the disorder determination circuit  30 .  FIG.  17    illustrates an inflow object residual disorder in a manner similar to that in  FIGS.  6  and  7   .  FIG.  18    is the diagram for explaining a method for determining the disorder level. 
     A column of the subject action after the end of the esophageal phase in  FIG.  17    illustrates a state in which a residue  8   b  (solid area) of the inflow object  8  flowed into the esophagus  6  by the subject remains in the pharynx  2 . In the example in  FIG.  17   , the residue  8   b  of the inflow object  8  remains in the pharynx  2  at a timing t 5  after a predetermined time has elapsed since the swallowing reflex was triggered. The above is an inflow object residual disorder caused by, for example, a decrease in the swallowing ability of the subject. The disorder determination circuit  30  can detect that the residue  8   b  remains in the pharynx  2  based on the color of a portion P 42   a  (solid area) in a picked-up image P 42  corresponding to the residue  8   b  in the case above. The example in  FIG.  17    illustrates a state in which the residue  8   b  does not remain in the pharynx  2  at a timing t 6  after a predetermined time from the timing t 5 . 
     The swallowing reflex detection circuit  28  detects the swallowing reflex triggering timing by determining that an image P 41  picked up by the image pickup apparatus  13  is a white-out image. The disorder determination circuit  30  detects the residue  8   b  by image analysis on the image picked up by the image pickup apparatus  13 . When dysphagia does not occur, as illustrated in  FIG.  6   , no residue  8   b  remains in the pharynx  2  after a predetermined time from the swallowing reflex triggering timing. On the other hand, in the case of the inflow object residual disorder, as illustrated in  FIG.  17   , the residue  8   b  remains in the pharynx  2  at the timing t 5  after the predetermined time from the swallowing reflex triggering timing. 
     The disorder determination circuit  30  reads the information on the swallowing reflex triggering timing from the timing recording memory  29 , and determines whether the residue  8   b  remains in the pharynx  2  after the predetermined time from the swallowing reflex triggering timing. When the disorder determination circuit  30  detects that the residue  8   b  remains in the pharynx  2  after the predetermined time has elapsed from the swallowing reflex triggering timing, the disorder determination circuit  30  may determine that the subject has developed the inflow object residual disorder. 
     The disorder determination circuit  30  may determine the inflow object residual disorder and the disorder level by not only the presence or absence of the residue  8   b , but also by comparing a duration that the residue  8   b  remains in the pharynx  2  with the determination reference time. In the case above, the disorder determination circuit  30  may detect the timing t 5  at which the residue  8   b  remains in the pharynx  2  and a timing t 6  at which the residue  8   b  disappears from the pharynx  2 , and store the timing information on the timings t 5  and t 6  in the timing recording memory  29  (not illustrated). 
       FIG.  18    illustrates the insertion detection timing, the swallowing instruction timing, the swallowing reflex triggering timing, and the inflow object residual time by solid rectangle positions with time on the horizontal axis. The example in  FIG.  18    indicates that a time t 13  is the inflow object residual time during which the residue  8   b  remains in the pharynx  2  after the swallowing reflex triggering timing. 
     The disorder determination circuit  30  may read the disorder level determination reference information from the memory  30   a  and determine the disorder level of the inflow object residual disorder by comparing the information on the determination reference time set in the disorder level determination reference information with the inflow object residual time. 
     In  FIG.  13   , for example, assuming that the swallowing videoendoscopy is performed using an inflow object that is easy to swallow in the first setting of the determination reference time, when the t 13  in  FIG.  18    is 1.5 seconds, the disorder determination circuit  30  determines that the subject has a mild inflow object residual disorder, when the t 13  is 5 seconds, the disorder determination circuit  30  determines that the subject has a moderate inflow object residual disorder, and when the t 13  is 25 seconds, the disorder determination circuit  30  determines that the subject has a severe inflow object residual disorder. When the t 13  in  FIG.  18    is 0.5 seconds, the disorder determination circuit  30  determines that the inflow object residual disorder has not occurred because the remained inflow object is within the normal range. 
     Although it has been described that the disorder determination circuit  30  detects that the residue  8   b  remains in the pharynx  2 , the inflow detection circuit  27  may detect the remaining and disappearance of the residue  8   b  and record the timing information on the detection in the timing recording memory  29 . 
     (Display of Determination Result) 
     The disorder determination circuit  30  generates display information to be presented to the operator or the like based on the determination result of dysphagia. The disorder determination circuit  30  converts the generated display information into a video signal that can be displayed on the monitor  40 , and then outputs the video signal to the monitor  40 . Thus, on the display screen of the monitor  40 , the information based on the determination result of dysphagia can be displayed. The disorder determination circuit  30  can also output the information on the determination result of dysphagia and the display information on the determination result of dysphagia to the output circuit  34 . 
     (Operation) 
     Next, operation according to the embodiment will be described with reference to  FIGS.  19  to  21   .  FIGS.  19  and  20    are flowcharts for explaining the operation of the main circuit  21 , and the same circled alphabetic letter in  FIGS.  19  and  20    indicates that the circled alphabetic letter connects steps.  FIG.  21    is a diagram illustrating a work flow of the swallowing videoendoscopy, swallowing actions, and endoscopic images (picked-up images) in a normal subject who has not developed dysphagia. 
     In step S 11  of  FIG.  19   , the control circuit  31  in the main circuit  21  controls the illumination device  22  and the developing circuit  23  to acquire an image picked up by the image pickup apparatus  13  of the endoscope  11  (endoscopic image), and provides the acquired image to the timing detection circuit  24 . The control circuit  31  also provides the audio collected by the microphone  33  to the timing detection circuit  24 . In step S 12 , the individual circuits in the timing detection circuit  24  execute image analysis on the inputted picked-up image and audio recognition processing on the audio signal from the microphone  33 . 
     In step S 13 , the individual circuits in the timing detection circuit  24  execute various kinds of timing detection. In the timing detection circuit  24 , the timing detection may be executed based on an operation signal of the input operation section. Although not clearly shown in  FIG.  19   , steps S 11  to S 13  are repeated until the swallowing videoendoscopy is completed. 
     That is, in step S 13 , the swallowing instruction detection circuit  25 , the endoscope insertion detection circuit  26 , the inflow detection circuit  27  and the swallowing reflex detection circuit  28  in the timing detection circuit  24  detect the swallowing instruction, the insertion of the endoscope, the inflow of the inflow object  8  into the pharynx  2 , and the triggering of the swallowing reflex, respectively. 
     In steps S 14  to S 17 , it is determined whether the insertion, the swallowing instruction, the inflow, and the triggering of the swallowing reflex are detected, respectively. Steps S 14  to S 17  may be executed in any order or may be executed simultaneously. 
     That is, when the endoscope insertion detection circuit  26  detects the insertion of the endoscope  11 , the endoscope insertion detection circuit  26  records the insertion detection timing in the timing recording memory  29 . When the swallowing instruction detection circuit  25  detects the swallowing instruction, the process proceeds from step S 15  to step S 19 . Then, the swallowing instruction detection circuit  25  records the swallowing instruction timing t 1  in the timing recording memory  29 . When the inflow detection circuit  27  detects the inflow of the inflow object  8 , the process proceeds from step S 16  to step S 20 . Then, the inflow detection circuit  27  records the inflow timing t 2  in the timing recording memory  29 . When the swallowing reflex detection circuit  28  detects the triggering of the swallowing reflex, the process proceeds from step S 17  to step S 21 . Then, the swallowing reflex detection circuit  28  records the swallowing reflex triggering timing t 3  in the timing recording memory  29 . 
     In step S 1  of  FIG.  21   , the operator inserts the endoscope  11  through the nasal cavity and moves the distal end portion thereof to the examination position. An image P 51  shows an endoscopic image acquired by the image pickup apparatus  13  in the case above. The endoscope insertion detection circuit  26  detects that the endoscope  11  has been inserted into the nasal cavity and the distal end portion thereof has reached the examination position, and records the insertion detection timing in the timing recording memory  29 . 
     In step S 2  of  FIG.  21   , the operator puts the inflow object  8  such as food for examination into the subject&#39;s mouth, and instructs the subject to hold the inflow object  8  in the oral cavity. Subsequently, the operator instructs the subject to swallow the inflow object  8  (step S 3 ). An image P 52  in  FIG.  21    shows an endoscopic image immediately after the swallowing instruction, and an image P 53  shows that the inflow object  8  has flowed into the pharynx  2 . 
     The swallowing instruction detection circuit  25  detects the swallowing instruction in step S 15  and records the swallowing instruction timing t 1  (step S 19 ), and the inflow detection circuit  27  detects the inflow of the inflow object  8  into the pharynx  2  in step S 16  and records the inflow timing t 2  (step S 20 ). Note that the example in  FIG.  21    illustrates an example of a normal case in which dysphagia does not occur, and in the case that the pharyngeal swallowing disorder occurs, the inflow timing t 2  may be detected earlier than the swallowing instruction timing t 1 . 
     In the example in  FIG.  21   , an image P 54  acquired immediately after the inflow of the inflow object  8  into the pharynx  2  is a white-out image indicating that the swallowing reflex has been triggered. The swallowing reflex detection circuit  28  detects the swallowing reflex triggering in step S 17  and records the swallowing reflex triggering timing t 3  (step S 21 ). Note that the example in  FIG.  21    illustrates an example of a normal case in which dysphagia does not occur, and in the case that the swallowing reflex disorder occurs, the swallowing reflex triggering may be detected after a relatively long time has elapsed from the swallowing instruction timing t 1  or the inflow timing t 2 . 
     In the present embodiment, dysphagia is automatically determined in the disorder determination circuit  30  based on the detected swallowing instruction timing t 1 , the inflow timing t 2 , and the swallowing reflex triggering timing t 3 . Therefore, the operator only needs to perform steps S 1  to S 3  in the swallowing videoendoscopy. 
     When the swallowing reflex triggering is detected in step S 17 , the swallowing reflex triggering timing t 3  is recorded in step S 21 , and then whether the residue such as food for examination remains in the pharynx  2  is detected (step S 22 ). An image P 55  in  FIG.  21    shows a normal example in which no inflow object remains, but in a case that the inflow object residual disorder occurs, an image in which the residue remains in the pharynx  2  is acquired. 
     If no residue is detected in step S 22 , the process proceeds to step S 23  and the disorder determination circuit  30  determines whether a predetermined time has elapsed. The step S 22  is repeated until the predetermined time elapses, and if no residue is detected during the period, it is determined that no residue remains, and the process proceeds to step S 18 . 
     When a residue is detected in the pharynx  2 , the disorder determination circuit  30  records a detection timing t 5  in the next step S 24 . Subsequently, the disorder determination circuit  30  determines whether the residue in the pharynx  2  has disappeared (step S 25 ). When the disorder determination circuit  30  detects the disappearance of the residue, the disorder determination circuit  30  records a detection timing t 6  of the disappearance (step S 26 ), and the process proceeds to step S 18 . 
     In step S 18 , the control circuit  31  determines whether the examination is completed. For example, the control circuit  31  may determine that the examination is completed when a predetermined examination time has elapsed from any of the timings t 1  to t 3 . Alternatively, the control circuit  31  may determine the completion of the examination by the operation of an input operation section (not illustrated) by the operator. If the control circuit  31  determines that the examination is not completed, the process returns to step S 11 , and if the control circuit  31  determines that the examination is completed, the process proceeds to step S 31 . 
     In step S 31 , the disorder determination circuit  30  reads information on the timings t 1  to t 3 , t 5 , and t 6  from the timing recording memory  29 . The disorder determination circuit  30  executes a first calculation for obtaining a difference between t 1  and t 2 , and executes a second calculation for obtaining a difference between t 1  and t 3  or a difference between t 2  and t 3  (step S 32 ). 
     In step S 33 , the disorder determination circuit  30  determines whether the result of the first calculation is within the normal range for the pharyngeal swallowing. For example, the disorder determination circuit  30  reads the disorder level determination reference information from the memory  30   a  and determines the presence or absence and the level of the pharyngeal swallowing disorder by comparing the information on the determination reference time included in the disorder level determination reference information with the first calculation result. For example, in the case in which the determination reference time defined by the information on the determination reference time included in the disorder level determination reference information is the first setting, when the first calculation result is 0.5 seconds, the disorder determination circuit  30  determines that the first calculation result is within the normal range and pharyngeal swallowing disorder has not occurred, and the process proceeds to step S 34 . For example, when the first calculation result is 25 seconds, the disorder determination circuit  30  determines that a severe pharyngeal swallowing disorder has occurred based on the first calculation result (step S 37 ), and then the process proceeds to step S 34 . 
     In step S 34 , the disorder determination circuit  30  determines whether the calculation result of the second calculation is within the normal range for the swallowing reflex triggering. For example, the disorder determination circuit  30  determines the presence or absence and the level of the swallowing reflex disorder by comparing the information on the determination reference time set in the disorder level determination reference information with the second calculation result. For example, in the case in which the determination reference time is the first setting, when the second calculation result is 0.5 seconds, the disorder determination circuit  30  determines that the second calculation result is within the normal range and swallowing reflex disorder has not occurred. Then, the process proceeds to step S 35 . For example, when the first calculation result is 25 seconds, the disorder determination circuit  30  determines that a severe swallowing reflex disorder has occurred based on the second calculation result (step S 38 ), and then the process proceeds to step S 35 . 
     In step S 35 , the disorder determination circuit  30  determines whether the timing t 5  has been detected. When the disorder determination circuit  30  determines that the timing t 5  has not been detected because no residue remains in the pharynx  2 , the process may proceed to step S 36 . When the first and second calculation results are within the normal ranges, the disorder determination circuit  30  determines that dysphagia has not occurred, and the process proceeds to step S 40 . 
     When the timings t 5  and t 6  are detected, the disorder determination circuit  30  determines the presence or absence and the level of the inflow object residual disorder by comparing the information on the determination reference time set in the disorder level determination reference information with the difference between t 5  and t 6 . For example, in the case in which the determination reference time is the first setting, when the difference between t 5  and t 6  is 0.5 seconds, the disorder determination circuit  30  may determine that the swallowing reflex disorder has not occurred. For example, when the difference between t 5  and t 6  is 25 seconds, the disorder determination circuit  30  may determine that a severe inflow object residual disorder has occurred (step S 39 ), and then the process may proceed to step S 40 . 
     Based on the determination results of steps S 37 , S 38 , S 36 , and S 39 , the disorder determination circuit  30  generates display information for presenting the determination result of dysphagia to the operator or the like, converts the generated display information into a video signal that can be displayed on the monitor  40 , and then outputs the video signal to the monitor  40 . Thus, the information based on the determination result of dysphagia is displayed on the display screen of the monitor  40  (step S 40 ). 
     In the above description, an example has been described in which three timings of the swallowing instruction timing, the inflow timing, and the swallowing reflex triggering timing are obtained to determine the pharyngeal swallowing disorder, the swallowing reflex disorder, and the inflow object residual disorder. However, in a case in which any one of the disorders is needed to determine, two of the three timings may be obtained. 
     As described above, in the present embodiment, at least two of the swallowing instruction timing, the inflow timing, and the swallowing reflex triggering timing are detected using the image information, the audio information, and the like acquired by the image pickup apparatus and the microphone. Thus, based on the time relationship between the respective timings, it is possible to automatically obtain the diagnostic results such as the pharyngeal swallowing disorder, the swallowing reflex disorder, and the inflow object residual disorder. Thus, even a person who is not an operator skilled in the swallowing videoendoscopy can make a more objective and quantitative diagnosis. 
     In addition, in the present embodiment, it is possible to output the information on the swallowing instruction timing, the inflow timing, and the swallowing reflex triggering timing, and it is also possible to use such kinds of timing information in other devices. 
     Second Embodiment 
       FIG.  22    is a block diagram illustrating another embodiment. In  FIG.  22   , the same constituent elements as those in  FIG.  1    are denoted by the same reference numerals, and descriptions thereof will be omitted. In the first embodiment, an example in which the swallowing videoendoscopy system is applied to one endoscope system has been described. The present embodiment illustrates an example applied to a plurality of endoscope systems. 
       FIG.  22    illustrates an endoscope system  61 , a database  60 , and a processing device  50 , which are located far away from each other and can communicate with each other. When the endoscope system  61  and the processing device  50  directly communicate with each other, the database  60  may be omitted. 
     Each of the endoscope systems  61 ,  62 , . . . has an image pickup function, an audio collecting function, a recording function for recording picked-up images and audio, and a communication function for transmitting recorded information, which are necessary for swallowing videoendoscopy. For example, each of the endoscope systems  61 ,  62 , . . . can include a general nasal endoscope, a microphone, and a video processor that processes images acquired by the nasal endoscope and audio collected by the microphone. That is, each of the endoscope systems  61 ,  62 , . . . can perform swallowing videoendoscopy according to the work flow in  FIG.  21   , record images and audio acquired from the swallowing videoendoscopy, and transmit the recorded images and audio to the database  60  as a case video with audio. 
     The database  60  is composed of predetermined storage devices, and can record the case videos with audio transmitted from the endoscope systems  61 ,  62 , . . . and transfer the case videos with audio to the processing device  50 . 
     The processing device  50  may be configured by a computer system using, for example, a personal computer or a tablet terminal. The processing device  50  includes a communication circuit  51 . The communication circuit  51  may be configured to enable communication such as wireless communication using a wireless LAN such as Wi-Fi or Bluetooth, or wired communication using a LAN cable. The communication circuit  51  can receive the case video with audio from the database  60  and supply the case video with audio to a timing detection circuit  24 . 
     In  FIG.  22   , the configurations of a timing detection circuit  24 , a timing recording memory  29 , and a disorder determination circuit  30  are the same as those in  FIG.  1   . Based on the video included in the case video with audio, an endoscope insertion detection circuit  26  detects an insertion detection timing, a swallowing instruction detection circuit  25  detects a swallowing instruction timing, an inflow detection circuit  27  detects an inflow timing of an inflow object, and a swallowing reflex detection circuit  28  detects a swallowing reflex triggering timing. 
     Other functions are the same as those of the first embodiment. 
     In the present embodiment, the processing device  50  can determine dysphagia by using case videos with audio acquired from the swallowing videoendoscopy at distant locations. 
     In order to efficiently perform swallowing diagnoses by a small number of doctors, for example, a number of swallowing videoendoscopy performed by technicians called speech-language pathologists (SLPs) increases in the United States. The SLP visits the patient to perform swallowing videoendoscopy, and uploads a recorded case video with audio to a database. The doctor downloads the case video with audio from the database and makes diagnosis while watching the case video with audio. 
     In the present embodiment, the case video with audio is downloaded from the database, and instead of the doctor, the processing device  50  detects the swallowing instruction timing, the inflow timing, and the swallowing reflex triggering timing to quantitatively evaluate the pharyngeal swallowing disorder, the swallowing reflex disorder, and the inflow object residual disorder, thereby providing diagnostic support. 
     As described above, in the present embodiment, diagnosis of dysphagia can be made using an acquired case video with audio of swallowing videoendoscopy at a distant location, so that objective, quantitative, and effective diagnostic support for the swallowing videoendoscopy can be provided, and the swallowing videoendoscopy can be made simpler. 
     The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the gist of the present invention at the implementation stage. In addition, various inventions can be formed by appropriately combining the plurality of constituent elements disclosed in the above embodiments. For example, some of all the constituent elements illustrated in the embodiments may be deleted. Furthermore, the constituent elements in different embodiments may be appropriately combined.