Endoscopic diagnosis system

1. An endoscopic diagnosis system, comprising:

a white light source for emitting white light;

a first narrowband light source for emitting first narrowband light which is light having a first central wavelength and has a portion of a wavelength range within a wavelength range of the white light;

a second narrowband light source for emitting second narrowband light which is light having a second central wavelength different from the first central wavelength and has a portion of a wavelength range within the wavelength range of the white light;

a light source controller for controlling on-off actions and light amounts of the white light source, the first narrowband light source and the second narrowband light source, respectively;

an image sensor for receiving reflected light from a subject illuminated with the white light to acquire a normal light image in a normal light observation mode, receiving reflected light from the subject illuminated with the white light and the first narrowband light emitted at a first emission ratio toward the subject to acquire a narrowband light image for blood vessel observation in a narrowband light observation mode, and receiving reflected light from the subject illuminated with the second narrowband light emitted toward the subject to acquire a narrowband light image for oxygen saturation level observation in an oxygen saturation level observation mode;

a controller for switching between the narrowband light observation mode and the oxygen saturation level observation mode alternately in this order to control such that the narrowband light image for blood vessel observation and the narrowband light image for oxygen saturation level observation are acquired alternately in a time-sharing manner;

an image processor for specifying a blood vessel region from image signals of the narrowband light image for oxygen saturation level observation, obtaining an oxygen saturation level of blood hemoglobin of the subject from signal ratios of the image signals for a pixel at a same position within the blood vessel region and from a look-up table regarding a correlation of the oxygen saturation level with the signal ratios, based on the image signals of the narrowband light image for blood vessel observation and the narrowband light image for oxygen saturation level observation to generate an oxygen saturation level image showing a distribution of the oxygen saturation level; and

a display unit for simultaneously displaying the narrowband light image for blood vessel observation and the oxygen saturation level image.

2. The endoscopic diagnosis system according to claim 1 , wherein, in the narrowband light observation mode, the image processor is adapted to generate a synthesized image in which the narrowband light image for blood vessel observation and the oxygen saturation level observation image are superposed, and

the display unit is adapted to display the synthesized image.

3. The endoscopic diagnosis system according to claim 1 ,

wherein, in the narrowband light observation mode, the image processor is adapted to generate a synthesized image in which the narrowband light image for blood vessel observation and the oxygen saturation level image are laid out, and

the display unit is adapted to display the synthesized image.

4. The endoscopic diagnosis system according to claim 1 ,

wherein the light source controller is adapted to control such that, a first illumination mode and a second illumination mode are switched alternately in the narrowband light observation mode, the white light and the first narrowband light being emitted to illuminate the subject at the first emission ratio in the first illumination mode, and the first narrowband light being emitted to illuminate the subject at the second emission ratio at which an emission amount of the first narrowband light is so reduced that an effect of the first narrowband light on the narrowband light image for blood vessel observation is ignorable in the second illumination mode, and

the image sensor is adapted to acquire the narrowband light image for blood vessel observation in the first illumination mode and the normal light image in the second illumination mode alternately in the narrowband light observation mode.

5. The endoscopic diagnosis system according to claim 4 ,

wherein, in the narrowband light observation mode, the image processor is adapted to generate a synthesized image in which the normal light image, the narrowband light image for blood vessel observation and the oxygen saturation level image are superposed, and

the display unit is adapted to display the synthesized image.

6. The endoscopic diagnosis system according to claim 4 ,

wherein, in the narrowband light observation mode, the image processor is adapted to generate a synthesized image in which the narrowband light image for blood vessel observation and the oxygen saturation level image are superposed, and

the display unit is adapted to display the normal light image and the synthesized image as being laid out.

7. The endoscopic diagnosis system according to claim 4 ,

wherein, in the narrowband light observation mode, the image processor is adapted to generate a synthesized image in which the normal light image, the narrowband light image for blood vessel observation and the oxygen saturation level image are laid out, and

the display unit is adapted to display the synthesized image.

8. The endoscopic diagnosis system according to claim 1 ,

wherein the first narrowband light has a wavelength range of 405 nm±10 nm, and the second narrowband light has a wavelength range of 473 nm±10 nm.

9. The endoscopic diagnosis system according to claim 1 ,

wherein the white light source comprises a third narrowband light source for emitting third narrowband light which is light having a third central wavelength different from the first central wavelength and the second central wavelength and has a portion of a wavelength range within the wavelength range of the white light and a fluorescent body which is excited to emit luminescent light when illuminated with the third narrowband light, so that the third narrowband light is combined with the luminescent light to generate pseudo white light.

10. The endoscopic diagnosis system according to claim 9 , wherein the third narrowband light has a wavelength range of 445 nm±10 nm.

11. The endoscopic diagnosis system according to claim 1 , further comprising:

a signal ratio calculator for specifying the blood vessel region from the image signals of the narrowband light image for oxygen saturation level observation based on a difference between an image signal of a blood vessel portion and an image signal of other portion.

12. The endoscopic diagnosis system according to claim 11 , wherein the signal ratio calculator obtains signal ratios B/G and R/G from image signals G and R respectively of a G channel and a R channel of the narrowband light image for blood vessel observation and from an image signal B of a B channel of the narrowband light image for oxygen saturation level observation for the pixel at the same position within the blood vessel region.

13. The endoscopic diagnosis system according to claim 12 , further comprising a correlation storage unit for storing the correlation of a blood volume and the oxygen saturation level with the signal ratios B/G and R/G in a form of the look-up table.

14. The endoscopic diagnosis system according to claim 13 , further comprising a blood volume-oxygen saturation level calculator for calculating the blood volume and the oxygen saturation level corresponding to the signal ratios B/G and R/G based on the correlation.

15. The endoscopic diagnosis system according to claim 14 , further comprising

an oxygen saturation level image generator, and

wherein the oxygen saturation level image generator has a color table in which color information is assigned depending on magnitude of the oxygen saturation level, and specifies the color information corresponding to the oxygen saturation level calculated in the blood volume-oxygen saturation level calculator by using the color table to generate a narrowband light image signal for oxygen saturation level observation reflecting the oxygen saturation level of blood hemoglobin.