KEYWORDS: Digital signal processing, Field programmable gate arrays, Data modeling, Apodization, Phased arrays, Signal processing, Model-based design, Ultrasonography, Data conversion, Finite impulse response filters
In this paper we present a model-based Field Programmable Gate Array (FPGA) design flow for ultrasound imaging using the delay-and-sum (DAS) beamforming technique. The beamformer model is based on DSP Builder toolbox in the Matlab/Simulink environment, used for fast prototype design and automatic hardware description language code generation for Intel FPGAs. The design was synthesized for an Intel Stratix IV FPGA and implemented on a Terasic DE4- 230 board, including the following digital signal processing steps: digital filtering, focusing delay adjustment, apodization, coherent summation, envelope detection and logarithmic compression. To evaluate our model, we used raw radiofrequency data from a phantom acquired using a 128-element convex transducer (2-5 MHz) with an active aperture of 8 elements. A Nios II processor was integrated into the FPGA to send and receive data from the model and transmit them to the host computer for off-line scan conversion and B-mode image generation. The results show that the proposed strategy is efficient for rapid prototyping of FPGA devices in ultrasound imaging applications. The overall FPGA resources utilization was less than 15%, indicating that other digital signal processing algorithms, such as interpolation, decimation, and scan conversion, can be implemented using this design methodology in both medical and non-destructive imaging applications.
The aim of the study is to demonstrate the potential of the fibre Braggs grating (FBG) in the measurement of different jaw movements that are performed for patients with occlusal parafunction using occlusal splints. Two silicon plates each 2mm are used, the fibre optic sensor is positioned in the maxillary left first molar region above the point of contact with opposing tooth after pressing the first plate on the model. Then the second silicon plate is pressed. The device has a final thickness of 2 mm. The occlusal splint is installed in the mouth of the patient who underwent different movements on occlusal splint. The maximum frequency bite is monitored. The results demonstrate that the bite shows a difference between grinding and clenching movements. The curves behaviour patterns are presented in order to show these different comparisons. Therefore, it is concluded that the fibre Braggs grating consists in an efficient method for monitoring the mechanical behaviour bite of patients with occlusal splints.
This study describes the evolution of a punctual method to determine the bite force. Now the fiber Bragg grating sensor is encapsulated in minimal material between uppers and lowers first molars, at the moment of occlusion, avoiding precontacts between the other teeth in a dentition model. The gypsum dentition castings were performed in semi-adjustable articulator in the occluded situation to maintain angulations of the occlusal plane of a volunteer. The sensor was characterized using loads from 0 to 90 N. Forces of about 0.0112 nm/N were found between right uppers and lowers first molars.
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