Irie T, Ohdaira E, Itoh K
Microsonic Co., Ltd., 3-9-11 Hongo Bunkyo-ku, Tokyo 113-0033, Japan.
Ultrasonics. 2004 Apr;42(1-9):713-6. doi: 10.1016/j.ultras.2003.11.020.
We measured the attenuation of ultrasound in animal bone in vitro, and determined successfully the correct dynamic range for the detection of echo signals from inside the bone. It was possible to display a B-mode image of a 6-mm thick porcine rib bone using a high frequency (5 MHz) transducer. However, it was difficult to obtain the image of a large bone (20-mm thick femur). This paper describes a possibility of the improvement for the detection of echoes from inside the bone using the FM-chirp pulse. An ultrasonic wave generator that generates the FM-chirp pulse for a frequency range of 100 KHz to 5 MHz was fabricated. And the pulse was transmitted from a transducer and received by a hydrophone in the water. The received waveform and the frequency spectrum were displayed on an oscilloscope. We measured the amplitude spectrum of the received waves before and after inserting a sample bone between the transducer and the hydrophone. In the experiment, three types of focused transducers (0.5, 1 and 2.25 MHz) and three kinds of sample bones (spine, femur and rib of a pig) were used. From the results of the measurement, we could find the useful information for imaging of inside the bone.
我们在体外测量了动物骨骼中的超声衰减，并成功确定了检测来自骨骼内部回波信号的正确动态范围。使用高频（5兆赫）换能器可以显示6毫米厚猪肋骨的B型图像。然而，很难获得大骨头（20毫米厚股骨）的图像。本文描述了使用调频线性调频脉冲改善从骨骼内部检测回波的可能性。制造了一种超声波发生器，它能产生频率范围为100千赫至5兆赫的调频线性调频脉冲。该脉冲从换能器发射，并由水中的水听器接收。接收到的波形和频谱显示在示波器上。我们测量了在换能器和水听器之间插入样本骨骼前后接收到的波的幅度谱。在实验中，使用了三种聚焦换能器（0.5、1和2.25兆赫）和三种样本骨骼（猪的脊柱、股骨和肋骨）。从测量结果中，我们可以找到有关骨骼内部成像的有用信息。
