Surgery – Truss – Pad
Patent
1996-10-21
1998-05-12
Jaworski, Francis
Surgery
Truss
Pad
A61B 800
Patent
active
057493634
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a reflection type ultrasonic osteoporosis diagnosing apparatus and method which diagnoses osteoporosis by radiating ultrasonic impulses towards a certain bone (cortical bone) of an examinee and determining echo levels from the surface of the bone;
BACKGROUND ART
With the emergence of an ageing society in recent years the bone disease termed osteoporosis has been becoming a problem. In this disease the calcium is withdrawn from the bones leaving them friable and prone to fracture at the slightest shock. Physical diagnosis is performed mainly by determining the density of bone precisely by means of diagnostic apparatus employing X-rays, typified by DXA apparatus; however, physical diagnosis by means of X-rays is beset by various problems such as the fact that the apparatus is large, and its use is restricted by the need to prevent damage due to radiation exposure.
Accordingly, diagnostic apparatus employing ultrasound have started to become popular as simple apparatus which do not cause such problems. In diagnostic apparatus employing ultrasound the speed and attenuation of ultrasound waves propagated inside the bony tissues are measured and used to estimate the density and elastic modulus (elastic strength) of the bone, and if a low estimated value is obtained it can be deduced that this is because of withdrawal of calcium from the bone, and hence osteoporosis is diagnosed.
For example, in the diagnostic apparatus recorded in Japanese Unexamined Patent 2-104337 and U.S. patent application Ser. No. 193,295 the speed of sound in bony tissue is measured by radiating ultrasonic pulses towards the bony tissue of an examinee which is the measurement site from an ultrasound transducer on one side and receiving the ultrasonic pulses transmitted by the bone tissue at an ultrasound transducer on the other side, and progress in osteoporosis is diagnosed when the speed of sound inside the bony tissue is slow. This is because this diagnostic apparatus acts on the premise that in experience the speed of sound in bony tissue is proportional to bone density.
However, the theoretical basis for linking bone density and the speed of sound is not established: strictly speaking the speed of sound in bony tissue is given by the square root of "the elastic modulus of the bone/bone density" and is not proportional to bone density. Moreover, because the elastic modulus of bone rises as bone density increases so that the modulus of elasticity of bone and bone density contribute to the speed of sound in such a way that they cancel one another out, the speed of sound in bony tissue cannot respond sensitively to an increase in bone density, and the coefficient of correlation between the speed of sound in bony tissue and bone density is decidedly not high. The theoretical basis for a link between bone density and attenuation of ultrasound waves is also not established.
Therefore it is unreasonable to expect highly reliable diagnoses from prior diagnostic apparatus which estimate bone density and the elastic modulus of bone from the results of determination of attenuation of ultrasound waves and the speed of sound in bony tissue.
This invention is a response to the situation above, and its purpose is to offer a reflection type ultrasonic osteoporosis diagnosing apparatus and method which, despite being simple and offering no risk of radiation exposure, can estimate bone density or the elastic modulus of bone more accurately (sensitively) than this sort of prior device and method, and can perform highly reliable diagnoses.
DISCLOSURE OF THE INVENTION
The osteoporosis diagnosing device of this invention diagnoses osteoporosis by setting an ultrasonic transducer against a certain skin surface of an examinee and repeatedly radiating ultrasonic impulses towards bone under the above skin while changing the direction of the emitting and receiving surface of the ultrasonic wave transducer within a certain range of solid angle which includes the line normal to the bone surface above, and for every
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patent: 5433203 (1995-07-01), Kimura et al.
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Ishii Tetsuya
Kubota Yasuyuki
Kuriwaki Masashi
Jaworski Francis
Sekisui Kagaku Kogyo Kabushiki Kaisya
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