| Summary: | 碩士 === 國立成功大學 === 醫學工程研究所 === 86 === Osteoporosis is one of the major health problems in the
world. The disease leading the loss in bone minieral is one of
the risk factors for fracture. Thus, how to prevent and to cure
the osteoporosis in advance is very important. Commonly used
methods of diagnosing osteoporosis, such as dual-energy X-ray
absoroptiometry (DEXA) and quantitative computed tomgraphy,
measure the quantitative aspect of bone mineral density(BMD).
Because these methods are associated with ionizing radiation,
patients are more likely in danger of being exposed to the X-
ray. In contrast to the ionizing electromagnetic radiation of
such clinical bone densitometric techniques, ultrasonic
measurement of bone has recently emerged as a promising
noninvasive technology for measurement of bone strength and
fracture risk. Ultrasound is a mechanical wave and thus
interacts with bone in a fundamentally distinct manner, so
ultrasound is viewed as having great potential for assessing
bone. In this paper, a new ultrasonic technique was
developed to measured the velocity of ultrasound waves
transmitted through the bone. This technique utilizes dual
transducer reflected ultrasound to measure acoustic speed of
bone tissue, where two transducers were placed on the same side
of the test object; one for the transmitter and receiver, and
the other one for the receiver only. The acoustic speed of bone
tissue can be easily obtained from the information of time-of-
flights on both transducers and the separation distance of these
two transducers without the knowledge of bone thickness which is
difficult to measure in biological tissue. Therefore, this
technique makes the clinical applications possible.
Twenty-three patients were tested in this study who also had
their bone mineral density measured by DEXA. The results showed
that the correlation between the sound speed measured by the
system and the bone mineral density measured by DEXA was 0.8856.
With high correlation of these two systems, it is a precise
method of assessing bone status without exposing the patient to
sources of radiation.
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