Timothy E. White

A128 X128 (16K) Ultrasonic Transducer Hybrid Array

Ultrasonic imaging in the low MHz frequency range with large two dimensional arrays presents many challenges in design and fabrication. In this paper, a 128 × 128 (16,384 total) element receiver array, consisting of a 1−3 composite piezoelectric transducer array bonded directly to large custom integrated circuits is described. This Transducer Hybrid Array (THA) is intended for use in a real-time 3D imaging system or acoustical camera (Fig. 1) for medical and underwater applications.

Imaging with a 2D Transducer Hybrid Array

Imaging with fully populated 2D arrays using acoustical lenses in the low MHz frequency range offers the potential for high resolution, real-time, 3D volume imaging together with low power and low cost. A 2D composite piezoelectric receiver array bonded directly to a large custom integrated circuit was discussed1 at the 23rd International Symposium on Acoustical Imaging. This 128 × 128 (16,384 total) element Transducer Hybrid Array (THA) uses massively parallel, on-chip signal processing and is intended for medical and underwater imaging applications. The system under development, which is a direct analog of a video camera, will be discussed in this paper.

Real-time 3D underwater acoustical camera

While laparoscopes are used for numerous minimally invasive procedures, minimally invasive liver resection and ablation occur infrequently. the paucity of cases is due to limited field of view and difficulty in determination of tumor location and margins under video guidance. By merging minimally invasive surgery with interactive, image-guided surgery, we hope to make laparoscopic liver procedures feasible. In previous work, we described methods for tracking an endoscope accurately in patient space and registration between endoscopic image space and physical space using the direct linear transformation (DLT). We have now developed a PC-based software system to display up to four 512 Χ 512 images indicating current surgical position using an active optical tracking system. We have used this system in several open liver cases and believe that a surface-based registration technique can be used to register physical space to tomographic space after liver mobilization. For preliminary phantom liver studies, our registration error is approximately 2.0mm. The surface-based registration technique will allow better localization of non-visible liver tumors, more accurate probe placement for ablation procedures, and more accurate margin determination for open surgical liver cases. The surface-based registration technique will allow better localization of non-visible liver tumors, more accurate probe placement for ablation procedures, and more accurate margin determination for open surgical liver cases. The surface-based/DLT registration methods, in combination with the video display and tracked endoscope, will hopefully make laparoscopic liver cryoablation and resection procedures feasible.

Imaging with a 16 000‐element 2‐D array

Imaging with acoustical lenses in the low MHz frequency range using fully populated 2‐D arrays offers the potential for high‐resolution, real‐time, 3D volume imaging, together with low power and low cost. A 2‐D composite‐piezoelectric receiver array bonded directly to a large custom‐integrated circuit is the enabling technology for a new implementation of the original acoustical imaging paradigm. This 128×128 (16 384 total) element transducer hybrid array (THA) uses massively parallel, on‐chip signal processing and is intended for medical and underwater imaging applications. The system under development, which is the acoustical analog of a video camera, will be discussed in this paper.