A concentric-ring equivalent phased array method to model fields of large axisymmetric ultrasound transducers

1999 ◽  
Vol 46 (4) ◽  
pp. 830-841 ◽  
Author(s):  
Xiaobing Fan ◽  
E.G. Moros ◽  
W.L. Straube
Keyword(s):  
Phased Array ◽  
Ultrasound Transducers ◽  
Concentric Ring

Catheter Ultrasound Phased-Array Transducers for Thermal Ablation: A Feasibility Study

2005 ◽  
Vol 27 (2) ◽  
pp. 89-100 ◽  
Author(s):  
Kenneth L. Gentry ◽  
Nasheer Sachedina ◽  
Stephen W. Smith
Keyword(s):  
Phased Array ◽  
Pulse Repetition Frequency ◽  
Heart Tissue ◽  
Single Element ◽  
Ultrasound Transducers ◽  
3D Scanner ◽  
Array Transducer ◽  
Ultrasound Ablation ◽  
Design And Testing ◽  
Ultrasound Scanner

The feasibility of catheter single-element ultrasound transducers for cardiac ablation has been shown previously. We describe the design and testing of catheter-sized linear phased arrays transducers for ultrasound ablation. One array has 86 PZT-4 elements operating at 8 MHz and 5 MHz. The overall array size is 14.9 mm by 3.1 mm (10 Fr). The other array has 50 PZT-5 elements operating at 4 MHz and is 17 mm by 3.1 mm (10 Fr). In order to produce the intensity needed to create lesions in heart tissue, we modified a real-time, 3D scanner to produce 100 Vpp 256-cycle transmit pulses at a pulse repetition frequency of 14.1 kHz. This made it possible for the PZT-4 and PZT-5 transducers to produce ISPTA of 3.26 W/cm2 and 142 W/cm2, respectively. When driving the transducers at high duty factor, the transmit circuitry in the scanner was damaged. A mechanically-focused transducer with the same dimensions as the PZT-4 transducer was built. When transmitting continuously at 9 MHz, it produced an ISPTA of 29.3 W/cm2. This created a lesion 5 mm across and 5 mm deep in beef tissue while raising the focal temperature 23°C. Ablation is within the capabilities of a catheter phased array transducer integrated into a diagnostic ultrasound scanner.

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