Research Of Human Enamel Imaging Method Based On Three-dimensional A-mode Ultrasound Reconstruction System

Dental diseases are very often encountered around the world due to improper diet and lackof necessary oral health knowledge. Most of them are related to the loss or erosion of humanenamel such as caries and decay. Therefore, it is extremely urgent for the visualization andimaging analysis of enamel.3D ultrasonic imaging, tracing back to1970’s, has manyadvantages, such as providing3D view and the corresponding slices of the organs, providingthe precise location and size of lesion by the measurement of3D space, and supportingzooming, rotation and so on. So it is widely used in modern medical ultrasonic diagnosis.3Dreconstruction system based on single element transducer, due to its scanning manner throughmechanical driving, can collect regular ultrasonic data of uniform pressure, constant scanningspeed and direction. Besides, the system uses such compact transducer with the advantages ofhigh axial resolution, so is properly for3D reconstruction of small organs such as teeth, eyesand so on.This paper is focused on two main contents: the development of3D reconstruction systembased on single element transducer and research on human enamel imaging methods. At first,this paper studies the basic principle of A_mode ultrasound, analyzes the advantages anddisadvantages of the existing3D ultrasonic reconstruction system, and then develops3Dultrasound reconstruction system, including3D translation platform, the signal acquisitioncard, computer, pulser-receiver and other hardwares. At the same time, the paper studies the3D human enamel imaging techniques. In order to get the strong RF echoes, the tooth samplessurface need to be polished to flat, or are scanned by complex rotation devices. To overcomethese drawbacks, with the aid of A_mode ultrasound3D reconstruction system, we proposethe linear TGC (Time gain compensation) method to enhance the raw RF signals collected bymechanical scanning, use discrete Hilbert transform to obtain the corresponding gray images,and use Visualization Toolkit for the subsequent3D display and measurement.In order to verify the resolution and operating characteristics of the system, a coin madeof steel and copper is placed in the water tank at25and reconstructed three times, and the nits diameter and thickness is measured respectively. Experiment results show that the measureerrors for the diameter and thickness using our system were0.28%±0.61%and0.18%±0.79%(mean error and standard deviation), respectively. Then, four human molars collected fromGuangzhou College of Stomatology, Sun Yat-sen University are scanned and3Dreconstructions and corresponding measurement were achieved. Experiment results show that based on the proposed methods the profile of the reconstructions closely reproduced that ofthe teeth under the premise of not undermine teeth body.