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3D ultrasound computer tomography (USCT) is an imaging method capable of producing volume images with both high spatial and temporal resolution. The promising results of a 2D experimental setup of an ultrasound computer tomography system showing structures of 0.1 mm in diameter encouraged us to build a new 3D demonstration system. The main problem of such a demonstrator is the high burst data rate of up to 36 GBytes per second for parallel recording of 1500 A-scans sampled at 12 MHz and 12 bit. We present a hardware setup for an experimental 3D demonstrator, which is capable of handling high data rates. This demonstrator for the first time allows high resolution (sub wavelength) 3D ultrasound imaging in almost realtime

Ultrasound computer tomography is an imaging method capable of producing volume images with both high spatial and temporal resolution. The promising results of a 2D experimental setup of an ultrasound computer tomography system with at least 0.25 mm resolution encouraged us to build a new 3D demonstration system. It consists of three parts: a tank containing the sensor system, a data acquisition hardware and a computer workstation for image reconstruction and visualization. For the sensor system we developed and manufactured our own low-cost transducer array emitting or receiving ultrasound signals in three dimensions. To optimize the transducer geometry in respect to aperture angle and pressure amplitude the pressure field was simulated using the ultrasound simulation program Field II. Each transducer arrays system carries 8 emitting and 32 receiving elements with integrated amplifier and address electronics. 192 A-scans can be recorded in parallel by the data acquisition hardware. 48 multiplexing steps are needed to store all A-scans of the 1536 receiving transducers. After recording the data is transmitted to the computer workstation.

Ultrasound computer-tomography (USCT) is a novel ultrasound imaging method capable of producing volume images with both high spatial and temporal resolution. Several thousand ultrasound transducers are arranged in a cylindrical array around a tank containing the object to be examined coupled by water. Every single transducer is small enough to emit an almost spherical sound-wave. While one transducer is transmitting, all others receive simultaneously. Our experimental setup, using only a few transducers simulating a ring-shaped geometry, showed even nylon threads (0.1 mm) with an image quality superior to clinical in-use ultrasound scanners. In order to build a complete circular array several thousand transducers, with cylindrical sound field characteristics, are needed. Since such transducer arrays are hardly available and expensive, we developed inexpensive transducer arrays consisting of 8 elements. Each array is based on a plate of lead titanate zirconate ceramics (PZT) sawn into 8 elements of 0.3 mm width, 3.8 mm height and 0.5 mm pitch. Each element has a mean frequency of 3.8 MHz and can be triggered separately. The main challenge was the development of production steps with reproducible results. Our transducer arrays show only small variances in the sound field characteristics which are strongly required for ultrasound tomography.