Ultrasound therapy uses high-frequency sound waves to produce heat that can reduce some types of acute and chronic pain and is often employed during physical, occupational or manipulation therapy to treat conditions such as musculoskeletal injuries, arthritis and fibromyalgia. Therapeutic ultrasound is typically delivered at frequencies between about 200 to about 10000 kHZ. Lowering the frequency of therapeutic ultrasound provides for deeper penetration of the sound waves. Sound waves penetrating the tissue of the subject cause molecules in the tissue to vibrate, producing heat and mechanical energy allowing for deep heating of tissues such as muscles, tendons, ligaments, joint capsules and bone. As is well known, therapeutic ultrasound differs from diagnostic ultrasound, which uses less-intense sound waves to create images of internal structure.
In the case of diagnostic ultrasound systems, compact electronics have been developed. For example, U.S. Pat. No. 5,924,993 to Hadjicostis et al. discloses an ultrasound mixed signal multiplexer/pre-amplifier application specific integrated circuit (ASIC) for supplying voltages to a group of transducer elements of an ultrasound array, receiving voltages from the same or another group of transducer elements of the ultrasound array, and amplifying the received voltages for transmission to external circuitry. The transmit and receive groups of transducer elements are shifted to provide accurate visual images with a minimal number of transmit and receive cycles.
U.S. Pat. No. 6,497,664 to Randall et al. discloses a medical diagnostic ultrasound receive beamformer including an upsampler upstream of both a time delay device and a summer, and a smoothing filter downstream of both the time delay device and the summer. The receive beamformer is automatically programmed into a gate array as a single-beam, dynamic-focus receive beamformer when the user selects B-mode and as a dual-beam, fixed-focus receive beamformer when the user selects color flow mode.
U.S. Pat. No. 6,969,352 to Chiang et al. discloses a hand-held ultrasound system including integrated electronics within an ergonomic housing. The integrated electronics include control circuitry, beamforming circuitry and transducer drive circuitry. The integrated electronics communicate with a host computer using an industry standard high speed serial bus. The ultrasound system is operable on a standard, commercially available, user computing device such as a personal computer (PC) without specific hardware modifications, and is adapted to interface with an external application without modification to the ultrasound system. This allows a user to gather ultrasonic data on the standard user computing device, and employ the data so gathered via the external application without requiring a custom system, expensive hardware modifications, or system rebuild. An integrated interface program allows such ultrasonic data to be invoked by a variety of external applications having access to the integrated interface program via a standard, predetermined platform such as Visual Basic or C++.
U.S. Pat. No. 7,169,108 to Little et al. discloses a continuous wave Doppler beam former application specific integrated circuit (CW-ASIC). The beam former may be a transmit or receive beam former. In one mode, the CW-ASIC is used in a diagnostic medical ultrasound system comprising a plurality of channels forming a CW analog receive path, wherein each channel is connected with a digital beam former. The plurality of channels are mixed down in quadrature to base band using a mixer and a local oscillator (LO) generator in quadrature. The outputs of the mixer are summed and wall/high pass filtered to provide a beam formed base band signal. A sub circuit provides a digital serial control function to interface to a real time control bus providing per channel enable/disable of the mixer and the LO generator, and LO delay as well as global local oscillator frequency select. The digital serial control function also has an external delay enable signal to start the LO generator and synchronize all the internal LO delays.
Although considerable attention has been paid to diagnostic ultrasound imaging systems, the same cannot be said as regards ultrasound therapy systems. The technologies described above relating to diagnostic ultrasound imaging systems are not applicable to therapeutic ultrasound delivery mainly due to the longer ultrasound bursts and higher time average power requried. As a result, there are still numerous barriers to the construction of fully electronically steerable, focused ultrasound devices for therapy including the number of transducer array elements, interconnects and driving and monitoring electronics that are required. As will be appreciated, further improvements in the design of ultrasound therapy systems are desired.
It is therefore an object of the present invention to provide a novel ultrasound therapy transducer head and ultrasound therapy system incorporating the same.