In vivo examination apparatus and capsule endoscope
Provided is an in vivo examination apparatus including an illumination unit emitting two types of illumination light in different wavelength bands; and an image acquisition unit having sensitivity to the wavelength bands of the two types of illumination light. Blood and background tissue have higher reflectances than a predetermined threshold to illumination light in a first wavelength band, blood has a lower reflectance than the threshold to illumination light in a second wavelength band, and a condition (R1 b /R1 a )>(R2 b /R2 a ) is satisfied, where R1 a is the reflectance of the background tissue to the illumination light in the first wavelength band, R1 b is the reflectance of the blood to the illumination light in the first wavelength band, R2 a is the reflectance of the background tissue to the illumination light in the second wavelength band, and R2 b is the reflectance of the blood to the illumination light in the second wavelength band.
1. An in vivo examination apparatus comprising:
an illumination device that emits illumination light in a first wavelength band having a center wavelength of 600 nm and illumination light in a second wavelength band having a center wavelength of 415 nm;
an image acquisition unit that is formed of an imaging optical system and an imaging element that has sensitivity to light in the two wavelength bands;
a storage unit that stores images acquired by the image acquisition unit; and
a control unit that controls the illumination device to make the illumination device emit illumination light in the two wavelength bands alternately in a time-division manner and that controls the image acquisition unit to make the image acquisition unit output, to the storage unit, images acquired when the illumination light in the two wavelength bands is radiated,
wherein a bandwidth of the first wavelength band includes wavelength ranges, in which the sensitivity is 25% or more of a sensitivity peak, in each of a R region and a G region overlap at a shorter wavelength side of the R region and a longer wavelength side of the G region;
a white-light image is generated from the illumination light in the first wavelength band and the illumination light in the second wavelength band by acquiring, with pixels of the imaging element having sensitivity to the R region, independent luminance information in the R region at a longer wavelength side of the first wavelength band, acquiring, with pixels of the imaging element having sensitivity to the G region, independent luminance information in the G region at a shorter wavelength side of the first wavelength band, and acquiring independent luminance information in the respective R, G, and B regions; and
blood and background tissue have higher reflectances than a predetermined threshold with respect to illumination light in the first wavelength band emitted from the illumination device, the blood has a lower reflectance than the threshold with respect to illumination light in the second wavelength band, and a following condition is satisfied,
( R 1 b/R 1 a )>( R 2 b/R 2 a ),
where R1a is the reflectance of the background tissue with respect to the illumination light in the first wavelength band, R1b is the reflectance of the blood with respect to the illumination light in the first wavelength band, R2a is the reflectance of the background tissue with respect to the illumination light in the second wavelength band, and R2b is the reflectance of the blood with respect to the illumination light in the second wavelength band.
2. A capsule endoscope comprising:
a capsule-like chassis; and
an in vivo examination apparatus according to claim 1 that is disposed in the chassis in a hermetically sealed manner.