Examination apparatus for measuring oxygenation in body organs

• US 4,907,876 A
• Filed: 05/02/1988
• Issued: 03/13/1990
• Est. Priority Date: 05/08/1987
• Status: Expired due to Fees

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Suzuki, Susumu, Hakamata, Naotoshi, Ozaki, Takeo, Yagi, Sumio
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US07/188,957
• Time in Patent Office: 680 Days
• Field of Search: 128/633, 250/207, 356/41, 356/325
• US Class Current: 356/41
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence

Abstract

An examination apparatus which measures the oxygenation in objects with near infrared light transmission spectrophotometry and that automatically adjusts a transmission light quantity to a magnitude suitable for detection by a photomultiplier tube. The examination apparatus comprises a ring-like ND filter whose transmission factor varies along its circumference, a filter driver for automatically setting a transmission factor of a filter, and a light source control device for automatically controlling output powers of light sources.

Claims

1. An examination apparatus for measuring the oxygenation in an object with electromagnetic wave transmission spectrophotometry, comprising:

plural light sources for emitting respective electromagnetic waves with different wavelengths;

light source control means for controlling said plural light sources so as to sequentially emit said electromagnetic waves;

an illumination-side fixture for making said electromagnetic waves introduced from said light sources incident on a measuring object;

a detection-side fixture for detecting electromagnetic waves transmitted from said measuring object and sending said transmitted electromagnetic waves to transmission light detection means;

said transmission light detection means for detecting said transmitted electromagnetic waves introduced from said detection-side fixture and outputting transmission light data; and

a computer system for controlling said light source control means and said transmission light detection means, and for receiving said transmission light data from said transmission light detection means and calculating the oxygenation in said measuring object;

wherein

said transmission light detection means includes filter means with a variable transmission factor for attenuating said transmitted electromagnetic waves and filter driving means for setting said transmission factor of said filter means; and

said light source control means and said filter driving means control output powers of said plural light sources and said transmission factor of said filter means, respectively, so that a light quantity outputted from said filter means become suitable for the detection.

2. An examination apparatus as claimed in claim 1, wherein optimum output powers of said respective light sources and optimum transmission factors for said respective electromagnetic waves with different wavelengths are previously determined at the beginning of the measurement and stored in said computer system, and said light source control mean and said filter driving means control said output powers of said plural light sources and said transmission factor of said filter means on the basis of said optimum output powers and said optimum transmission factors being stored in said computer system, respectively, in the actual oxygenation measurement.

3. An examination apparatus as claimed in claim 1, wherein

said filter means is a ring-like ND filter whose transmission factor gradually varies along its circumference;

and

said filter driving means is a motor which sets said transmission factor of said ring-like N/D filter by locating an appropriate portion of said ring-like ND filter in the optical axis by rotating said ring-like ND filter according to an instruction from said computer system.

4. An examination apparatus as claimed in claim 1, wherein

said filter means is a liquid crystal panel whose transmission factor varies with an applied driving voltage;

and

said filter driving means receives a control signal from said computer system, converting said control signal into a transmission factor signal, and applies an appropriate driving voltage corresponding to said transmission factor signal to said liquid crystal panel.

5. An examination apparatus for measuring the oxygenation in an object with the electromagnetic wave transmission spectrophotometry, comprising:

light source means for emitting electromagnetic waves with respective different wavelengths;

light source control means for controlling said light source means so as to sequentially emit said electromagnetic waves;

an illumination-side fixture for making said electromagnetic waves introduced from said light source means incident on a measuring object;

a detection-side fixture for detecting electromagnetic waves transmitted from said measuring object and sending said transmitted electromagnetic waves to transmission light detection means;

said transmission light detection means for detecting said transmitted electromagnetic waves introduced from said detection-side fixture with a photomultiplier tube and outputting transmission light data, said transmission light detection means further includes a photon-counter and an analog detector for detecting an output current from said photomultiplier tube, said output current from said photomultiplier tube is detected by said photon-counter with a photon-counting mode when a transmission light quantity incident on said photomultiplier tube is small, and is detected by said analog detector with an analog detection mode when said transmission light quantity is large, and said transmission light detection means further includes a detection controller for receiving said output current from said photomultiplier tube and for selecting the detection mode from said photon-counting mode and said analog detection mode and controlling a voltage applied to said photomultiplier tube according to said received output current; and

a computer system for controlling said light source control means and said transmission light detection means, and for receiving said transmission light data from said transmission light detection means and calculating the oxygenation in said measuring object;

wherein

said transmission light detection means detects each of said transmitted electromagnetic waves with a detection mode suitable for intensity of each of said transmitted electromagnetic waves.

6. An examination apparatus as claimed in claim 5, wherein appropriate detection modes for said respective electromagnetic waves with different wavelengths are previously determined at the beginning of the measurement and stored in said computer system, and said computer system controls said transmission light detection means on the basis of said stored appropriate detection modes so that said detection mode is appropriately selected in the actual oxygenation measurement.

7. An examination apparatus for measuring the oxygenation in an object with electromagnetic wave transmission spectrophotometry, comprising:

light source means for emitting electromagnetic wave with respective different wavelengths;

light source control means for controlling said light source means so as to sequentially emit said electromagnetic waves;

an illumination-side fixture for making said electromagnetic waves introduced from said light source means incident on a measuring object;

a detection-side fixture for detecting electromagnetic waves transmitted from said measuring object and sending said transmitted electromagnetic waves to transmission light detection means;

said transmission light detection means for detecting said transmitted electromagnetic waves introduced from said detection-side fixture with a photomultiplier tube and outputting transmission light data, said transmission light detection means further includes a photon-counter and an analog detector for detecting an output current from said photomultiplier tube, and said output current from said photomultiplier tube is detected by both of said photo-counter and said analog detector with a photon-counting mode and an analog detection mode, respectively, for each of said electromagnetic waves with different wavelengths, and a computer system selects appropriate transmission light data from transmission light data obtained with said photo-counting mode and said analog detection mode; and

said computer system for controlling said light source control means and said transmission light detection means, and for receiving said transmission light data from said transmission light detection means and calculating the oxygenation in said measuring object;

wherein

said transmission light detection means detects each of said transmitted electromagnetic waves with a detection mode suitable for intensity of each of said transmitted electromagnetic wave.