Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2000-10-27
2003-04-01
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S344000, C600S322000
Reexamination Certificate
active
06542763
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to equipment for imaging and measuring information of a light scattering object, particularly, information inside a biological body using light.
A system which can measure blood circulation, blood circulation movement and oxygen metabolism inside a biological body with a low restraint to a test object (a person to be tested) and without causing harm to the biological body is required in a field, such as clinical medicine, and also brain science. When, for example, the head is an object to be measured, the measuring of a brain disease, such as the cerebral infarction, cerebral hemorrhage and insanity, as well as the measuring of a higher level brain function, such as thinking, language and exercise can be raised as specific needs. Also, such a measured object is not limited to the head, so that preventive diagnosis in connection with heart disease, such as myocardial infarction, as used for measuring the breast, to an internal organ disease, such as kidney disease and liver disease, as well for measuring the abdomen, and further measuring of oxygen metabolism in the muscle of the hand and foot can be raised as specific needs.
In the case where the head is a measured object, in the measurement of brain disease or a higher level brain function, it is necessary to clearly specify a zone of the diseased portion or a zone of the brain function. Therefore, the imaging measurement of the brain becomes important.
Of course, the importance of imaging measurement is not limited only to the brain, but the same can be said to apply to the measurements of the beast, the abdomen and so on.
As examples, it can be mentioned that the positron emission tomography (PET) and the functional magnetic resonance imager (fMRI) and the cerebral magnetic field measurement system (MEG) are widely used in the imaging measurement of the brain function. These systems have an advantage in that an active zone inside the brain can be measured as an image, but, on the other hand, they have a disadvantage in that the systems are large in size and the operation is very complex. For example, a large dedicated room is required to install the system, and, of course, it is difficult in practice to frequently move the system. Further, the restraint to the tested person is very high, because the tested person is forced to maintain a fixed posture for a long time inside the system during measurement; and, accordingly, he or she is forced to withstand a certain amount of mental and physical pain. Furthermore, the cost required for operating the system is large because a dedicated person to maintain and manage the system is required.
On the other hand, as a method of measuring blood circulation, blood circulation movement and oxygen metabolism inside a biological body with a low restraint on the tested person and without causing harm to the biological body (non-infestation), optical measurement is very effective. The first reason is that the blood circulation and the oxygen metabolism in a biological body correspond to a concentration and a change in the concentration of a specific pigment (hemoglobin, cytochrome, myoglobin etc.) in the biological body, and the concentration of the pigment can be measured from an amount of absorption of light having wavelengths within a range from visual to infrared light. The blood circulation and the oxygen metabolism are indicative of a normal or abnormal condition of the organ in the biological body and further indicate activity of the brain in regard to a higher level brain function. In addition, the second reason for the effectiveness of optical measurement is that the system can be made small in size and the measurement can be easily performed because of the technological development of laser diodes, light emitting diodes and photodiodes. Further, the fixing of the head during measurement becomes unnecessary by employing highly flexible optical fibers in the measurement, and, accordingly the restraint of the tested person can be largely reduced and the mental and physical pain endured by the tested person can be largely reduced. Furthermore, the third reason is that the optical measurement does not cause harm to the biological body when using light having an intensity within a safety standard range.
In addition to the advantages described above, the optical measurement has advantages of real time measurement, quantification of pigment concentration in a biological body and so on which the PET, the fMRI and the MEG do not have. In making use of these advantages of the optical measurement, systems which measure the inside of a biological body by illuminating light having wavelengths within a range from visual to infrared light onto the biological body and detecting reflected light from the biological body are disclosed, for example, in Japanese Patent Application Laid-Open No. 57-115232 and Japanese Patent Application Laid-Open No. 63-275323. Further, systems for imaging a biological body using optical measurement are disclosed in Japanese Patent Application Laid-Open No. 7-79935, Japanese Patent Application Laid-Open No. 9-19408 and Japanese Patent Application Laid-Open No. 9-149903. Furthermore, the effectiveness of the imaging measurement on a biological body using light is described, for example, in an article entitled “Spatial and temporal analysis of human motor activity using noninvasive NIR topography”, by Atsushi Maki et al., Medical Physics, Vol. 22, pages 1997 to 2005 (1995).
In the non-invasive imaging measurement of a biological body using light, it is necessary to illuminate light beams onto a plurality of positions and to detect light beams from a plurality of positions. In that case, in order to further improve the optical measurement so that it is higher in accuracy and higher in sensitivity, additional circuits, such as a modulation adding, a modulation measuring, a temperature control, an optical intensity control, and temperature compensating circuits are necessary for the opt-semiconductor elements, such as a laser diode and a photodiode. Therefore, it is difficult to mount such an opt-semiconductor element directly on the test object. In order to make such measurement practically possible, light illumination and light detection using many optical fibers are required. However, Japanese Patent Application Laid-Open No. 7-79935 does not disclose in what arrangement each of the plurality of optical fibers used for the measurement is mounted on the test object in order to perform the desired image measurement.
On the other hand, in Japanese Patent Application Laid-Open No. 9-19408 and Japanese Patent Application Laid-Open No. 9-149903 and the cited article in Medical Physics, methods of efficiently arranging optical fibers on a test object are disclosed in detail. According to these methods, assuming that a square area having a side of 6 cm in the head is measured as a limited zone, four incident optical fibers for each of four incident positions and five detecting optical fibers for each of detection positions, that is, nine optical fibers in total, are necessary. Therefore, since the measurement position is a midpoint between the incident position and the detection position adjacent to each other, twelve measurement positions in total are set. In the field of the clinical medicine and the brain science, it is required to measure brain activity in a wide region. When a square area having a side of 12 cm is intended to be measured by applying the above-mentioned method of arranging the incident positions and the detection positions, twelve incident optical fibers and thirteen detecting optical fibers, that is, twenty-five optical fibers in total are necessary. When the measured area is further expanded, the number of optical fibers to be mounted is further increased and exceeds 100 depending on the circumstances. The prior art described above shows a part of the measurement principle in the non-invasive imaging measurement of a biological body using light, but does not disclose any display nor any function for
Kawaguchi Fumio
Koizumi Hideaki
Maki Atsushi
Yamamoto Tsuyoshi
Yamashita Yuichi
Antonelli Terry Stout & Kraus LLP
Hindenburg Max F.
Hitachi , Ltd.
Kremer Matthew J
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