Ultrasonic probes provide a convenient and accurate way of gathering information about various structures of interest within a medium under examination by the probe. For example medical ultrasonic probes provide a convenient and accurate way for a physician to collect imaging data of various anatomical parts, such as heart tissue or fetal tissue structures within a patient. It has been discovered that making such imaging data available to surgeons allows otherwise risky surgical procedures to be performed safely. Furthermore, since physicians can now make treatment decisions from results of ultrasound imaging, unnecessary exploratory surgery can be avoided. This has been proven to save money and reduce risks to patients.
In operation, such ultrasonic probes generate a beam of acoustic signals, which is transmitted into the patient and is reflected by various anatomical parts within the patient. The beam is focussed at various depths within the patient and is scanned vertically and horizontally so that the reflected acoustic signals provide three dimensional image data about the various anatomical parts within the patient. The reflected signals are received, analyzed, and processed to produce an image display that is representative of the anatomical parts of the patient.
Early ultrasonic probes were mechanically scanned in one or two dimensions. While such early probes provided some advantages, mechanically scanning could be done at only a limited rate. Furthermore, because a single acoustic lens provided an acoustic beam focussed at only one depth within the patient, such early probes did not provide three dimensional image data at various depths within the patient.
More recent ultrasonic probes provide features such as electronic beam steering and electronic focussing, by using beam forming channels to control amplitude and phasing of a two dimensional array of piezoelectric ceramic transducer elements. Electronic beam steering provides beam scanning at a rate that is much faster than that which is possible with mechanical scanning. Furthermore, electronic focussing provides a flexible way of focussing the acoustic beam at various depths within the patient. Accordingly, such two dimensional arrays provide three dimensional ultrasonic imaging capabilities.
In a typical array of the prior art, each acoustic signal channel requires a respective one piezoelectric ceramic transducer element of the array coupled with a respective one beam forming channel through a respective one signal cable. A large number acoustic signal channels is desirable to provide high resolution acoustic imaging. Accordingly, previously known arrays included a large number of separate piezoelectric ceramic transducer elements, a large number of signal cables, and a large number of beam forming channels to provide high resolution acoustic imaging.
While features such as high resolution acoustic imaging, electronic beam steering, and electronic focussing provide many advantages, two dimensional arrays of the prior art that provide such features are typically difficult and expensive to construct because of a large number of elements, beam forming channels, and cables that are used. For example, in accordance with some teachings of the prior, to provide a high acoustic imaging resolution corresponding to a large number, N.sup.2, of acoustic signal channels, requires an array of a large number, N.sup.2, of separate piezoelectric ceramic transducer elements, a large number, N.sup.2, of signal cables, and a large number, N.sup.2, of beam forming channels. Therefore, according to some teachings of the prior art, high acoustic imaging resolution of a 128 by 128 array of piezoelectric ceramic transducer elements 16,384 signal cables and a set of 16,384 beam forming channels. Such large numbers of signal cables and beam forming channels greatly increases the size, cost, and complexity of an acoustic imaging system.
Typically, the signal cables are bound together in a bundle of cables that extends between a probe head and a base station. Ideally, the bundle of cables would be light, thin, flexible, and easy to handle. However as the number of array elements is increased to provide the large number of acoustic signal channels, a number of control cables of the bundle also increases, so that the bundle of cables becomes heavy, thick, bulky, expensive, and more difficult to handle.
What is needed is a new probe having a reduced number of beam forming channels and signal cables, while still providing high resolution acoustic imaging.