Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Patent
1998-04-03
1999-08-31
Kamm, William E.
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
A61B 0800
Patent
active
059446650
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to ultrasonic diagnostic apparatus utilized in diagnosing osteoporosis, for instance. More particularly, the invention relates to apparatus which obtain information on characteristics of a body part to be examined by producing sound waves which are passed through the body part positioned between a pair of transducers.
BACKGROUND ART
Osteoporosis is a symptom characterized by a decrease in the density of bone structures due to a lack of calcium, for instance. One method of diagnosing osteoporosis having been heretofore proposed is to quantitatively determine a bone characteristic (e.g., bone salt density) by passing ultrasonic waves through a bone and measuring the propagation speed of sound (SOS) in the bone. An ultrasonic examination of this kind is usually performed on a heel of the foot where the thickness of soft tissue is small.
A conventional apparatus (which is referred to as an ultrasonic bone-salt determination apparatus) for measuring the bone characteristics in the aforementioned fashion is movably mounted on a platform and, thus, makes use of a pair of movable parts with an ultrasound generator and an ultrasound detector installed face to face with each other individually on inside walls of the movable parts. A human heel is placed between the movable parts to interrupt a straight path between the ultrasound generator and detector, and the movable parts are repositioned such that the ultrasound generator and detector come in close contact with the heel in the air to permit propagation of ultrasonic waves. If ultrasound is emitted from the generator in this condition, it propagates at a speed that is dependent upon the bone salt content of the heel bone when passing through it. Thus, it is possible to measure a quantity corresponding to the bone salt content of the heel bone, which is the body part to be examined, by determining the speed of sound (SOS) of the ultrasound with the detector.
Specifically, the speed of sound (SOS) (SOS=L/T (m/s)) in the body part to be examined (heel) is derived from the distance L between the ultrasound generator and detector and the travel time T needed for a sound signal to propagate through the heel obtained by the ultrasound to pass through the body part to be examined (heel) as described above. The speed of sound (SOS) is converted into the corresponding bone salt content of the body part to be examined (heel) and, then, a judgment is made concerning the presence or absence of osteoporosis mentioned above. The apparatus intended for use in the above-described diagnosis is referred to as a dry-type ultrasonic diagnostic apparatus.
A pair of movable parts are used in the aforementioned dry-type ultrasonic diagnostic apparatus due to the need for holding the ultrasound generator and detector in close contact with the body part to be examined (heel). This arrangement, however, has made it essential to measure the aforesaid distance L (i.e., the distance L between the ultrasound generator and detector) each time a measurement is made by passing the ultrasound through the body part to be examined (heel). Further, it is necessary to move the individual movable parts by using a robust, precision mechanism and prepare an electric signal processing system featuring good linearity and high resolution for measuring the distance L with a high degree of accuracy. It has, however, been difficult to measure it with good accuracy, which results in an increase in the cost of the apparatus itself. Since it has been difficult to measure the distance L between the ultrasound generator and detector with good accuracy as stated above, the propagation speed of sound (SOS) determined would vary from one measurement to another or contain a significant error, rendering measurement results unreliable.
A previously proposed solution to the aforementioned problems is found in an ultrasonic diagnostic apparatus described in Japanese Unexamined Patent Publication No. 5-228148. This kind of apparatus employs a frame associated with an ultraso
REFERENCES:
patent: 5749363 (1998-05-01), Ishii et al.
Hiraoka Yasushi
Iino Hiroshi
Kajiwara Atsushi
Nobunaga Kazuhiko
Takase Masahiro
Furuno Electric Co. Ltd.
Kamm William E.
Patel Maulin
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