| 摘要 |
The stainless steel needle is designed for use in conjunction with an ultrasonic scanner to allow visual control of difficult medical punctures, e.g. of the amnion. It reflects ultrasonic waves the more clearly for having circumferential grooves at a spacing to suit the ultrasonic wavelength. Groups of grooves are separated by plain stretches for easier identification on the scanner's screen. The grooves are right-angled triangular in cross section. For smooth insertion in the body the whole needle is sheathed in Teflon, which also fills the grooves. This material is chosen as having ultrasonic properties similar to those of body tissue. |
