An ultrasonic sensing and indentation apparatus for assessment of tissue geometry and mechanical properties

Abstract

Measuring the distance from the skin to the bone and soft tissue mechanical properties is important to custom designing prosthetic sockets for amputee patients using a computer aided method. The current state-of-the-art method to obtain such information is via MRI scans. However, MRI scans are expensive, not widely accessible, and may not be as accurate if there is a time gap between when the MRI scan is taken and when the design process takes place. In this thesis, I designed and implemented a hand-held apparatus which measures both the skin-to-bone depth and soft tissue mechanical properties. With a PC interface, this method involves gathering and processing data from an ultrasound transducer, a force sensor, and an accelerometer. The procedure of use involves rotating the apparatus around the limb while maintaining a light contact to acquire skin-to-bone depth, and indenting the apparatus into the limb to acquire soft tissue mechanical properties. Here I show that a miniaturized apparatus as such can measure tissue boundaries and tissue indentation with sub-millimeter precision and out performs a commercial ultrasound imaging system in my case study, which makes custom computer prosthetic socket design easier, more affordable, and more accessible.