Development of flexible 2D ultrasound arrays for scoliosis assessment

Abstract

Conventional way of assessing scoliosis requires taking X-ray radiograph on the coronal plane of the spine. Rapid radiograph examinations on scoliosis patients could produce radiation hazards and increase the risk of cancer. Recently, it has been shown that ultrasound imaging could produce reliable Cobb’s angle measurement for scoliosis assessments. However, this method requires moving the ultrasound probe manually by physician’s hand and could produce error if subjects moved during the imaging process. More importantly, it is very difficult to take images when subjects are wearing back braces. This study has aimed to overcome the above issues by developing a flexible ultrasound transducer arrays which could stay on subjects’ back during the examination. 4mm diameter piezoelectric transducer elements were soldered onto flexible copper Printed Computer Board (PCB). The transducer surface was then emerged into soft silicone gel to eliminate possible air gaps and provide comfortable cushioning between transducer and the subject’s back. Accelerometers and electromagnetic spatial sensors were explored to measure the elements’ location and orientation. The Preliminary results showed that the structure of the spinous process could be identified with the flexible transducer array by comparing A-mode signals with B-mode images taken with conventional ultrasound probe. It was also suggested that the larger angular coverage of the flexible transducer array could be helpful for studying the orientation of reflecting surface. This could be done by finding the angle of reflection of the echoes by capturing signals with nearby elements during single element stimulation.