Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2002-03-08
2003-07-08
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C310S334000, C029S025350
Reexamination Certificate
active
06589180
ABSTRACT:
FIELD OF INVENTION
This invention relates to methods for constructing high density, exceptionally complex and compact ultrasound arrays using interconnected, multi-layer structures composed of active integrated circuit devices on various planar substrates and passive devices, and more particularly, to using electrically conducting micro-bump interconnections between layers, and conductors within micro-vias for electrical connections through the semiconductor or other substrates, to realize the implementation in a single device of segregated sections or different integrated circuit technologies on a layer-by-layer basis.
BACKGROUND
Diagnostic ultrasound is an established and growing medical imaging modality. Currently one-dimensional arrays with up to 128 elements are the standard in the industry. Separate coaxial cables are used to connect the elements to the system electronics. Improved image quality requires the use of matrix (n×m) arrays with a thousand or more elements. As element numbers increase and their dimensions grow smaller, limitations to present fabrication technologies arise. Cost, ergonomics, produce-ability and reliability are important issues. Signal loss due to the capacitance of the coax cables becomes a fundamental problem.
Connecting an integrated circuit directly to the array elements alleviates all these problems. Each unit cell of such a custom Transmitter/Receiver Integrated Circuit (TRIC) may have high voltage switches for transmitting; a preamplifier which minimizes signal loss and a multiplexer to send the array signals over fewer wires. Additional signal processing and beam forming may also be included.
This disclosure first discusses the history and current state-of-the art in medical diagnostic ultrasound, emphasizing arrays, their limitations and issues.
Diagnostic ultrasound is an established, cost-effective medical imaging modality. More than 400,000 systems are in use throughout the world. This stage of development has been achieved over the last 30 years for several reasons. The equipment and exam costs are lower than competing medical imaging technologies. Structural information about normal organs and soft tissue (non-bone) and pathologies is easily obtained. Functional information such as blood flow, organ perfusion or movement of heart valves is easily obtained. The systems are portable and only require a typical examining room. Finally, it is generally considered to be non-invasive.
Medical ultrasound systems transmit a short pulse of ultrasound and receive echoes from structures within the body. The handheld probes are most often applied to the skin using a coupling gel. Specialty probes are available for endocavity, endoluminal and intraoperative scanning.
Almost all systems on the market today produce real-time, grayscale, B-scan images. Many systems include colorflow imaging. Real-time images move as the operator moves the probe (or scanhead). Moving structures, such as the heart or a fetus, are shown on the video monitor. Grayscale images depict the strength of echo signals from the body as shades of gray. Stronger signals generally are shown as bright white. Lower signals become gray and echo-free regions are black. B-scans are cross-sectional or slice images. Colorflow imaging adds a color overlay to the black and white image to depict blood flow.
Over the last 30 years, the major technical developments that have improved imaging or added diagnostic capability. Digital technology provided image stability and improved signal processing. Real-time imaging provided quicker, easier imaging and functional information. Electronically scanned linear arrays, including sequenced arrays and phased arrays, provided improved reliability. Color-flow imaging opened up new cardiac and vascular applications. Digital beamformers improved image quality. Harmonic imaging provided improved image quality particularly in difficult to image patients. Coded-excitation imaging permitted increased penetration allowing use of higher frequency ultrasound, thereby improving image contrast. Contrast agents offer improved functional information and better image quality. And 3D (volumetric) imaging presents more easily interpreted images of surfaces such as the fetal face.
One-dimensional (1D, linear or 1×m) transducer arrays, either flat or curved, having as many as 128 transducers, are the conventional electronically scanned arrays in widespread use today. Matrix arrays consisting of (n×m) elements will be required in future systems to improve image quality. All such arrays on the market today are connected to the system electronics through a bundle of coaxial cables. Beamformers in the system electronics adjust the time delays between channels to provide electronic sector scanning and focusing. High performance systems typically use all 128 elements in their beamformers. Lower performance systems may use as few as 16 of the 128 elements at any instant. The scanning function is performed by switching elements into the aperture on the leading edge of the scan and switching out elements at the trailing edge.
When a pulse is transmitted by an array, transmitter time delays on each channel are adjusted to provide a focusing effect. For reception of echoes, time delays between channels are adjusted in real-time as the pulse propagates into the body. This dynamic, or tracking focus, sweeps out from the probe into the body at the velocity of sound. Almost all ultrasound systems use dynamic focusing, which provides greatly improved resolution and image quality in the scanning plane.
1.25D arrays typically use a (128×3) or (128×5) matrix. They are connected to the system electronics through a similar bundle of coax cables as the 1D array. The same beamformers are also used for scanning and dynamic focusing. As the pulse propagates into the body, only the center element is initially selected for receiving the reflected signals. By switching in additional elements as the pulse propagates, the receiving aperture is enlarged and the receiver is weakly focused.
1.5D arrays use a (128×n) matrix, with n an odd number, typically 5, 7 or 9.1.5D arrays use dynamic focusing in the plane perpendicular to the scanning plane. This produces optimal resolution in all dimensions, further reducing artifacts. The key difference between the 1.25D and 1.5D arrays is the active time-delay beamforming in both dimensions. The number of elements in the elevation direction is often an odd number because elements on each side of the beam axis are electrically connected together since they both have the same time delay for on-axis targets.
1.75D arrays are very similar to 1.5D arrays with the exception that the elements in the elevation direction are individually connected to the beamformer. Limited angular beamsteering can be performed in addition to dynamic focusing. Aberration correction is also possible with the 1.75D array. These added capabilities are not present in a 1.5D array, which only provides improved focusing for on-axis targets.
2D transducer arrays are the most general type, with (n×m) elements. Dynamic focusing as well as sector beamsteering in any arbitrary direction around the axis normal to plane of the array is possible. The angles are only limited by the constraints of the beam former, the number of elements and their dimensions.
The use of larger multi-dimensional arrays introduces problems of circuit density in the supporting substrate, to a much greater extent than the linear arrays currently in use. Although the 1.25D array produces moderate improvement, the improved image quality of 1.5D and 1.75D arrays will make a quantum jump in resolution, image quality and freedom from artifacts, which suggests that resolution of the circuit density problems is very important.
All linear arrays currently on the market use piezoelectric materials as the transducing mechanism from electrical signals to ultrasound (transmitter) and ultrasound back to electrical signals (receiver). The signals are generally in the form of short pulses or tone
Erikson Kenneth R.
Marciniec John
White Timothy E.
Bae Systems Information and Electronic Systems Integration Inc
Imam Ali M.
Lateef Marvin M.
Maine & Asmus
LandOfFree
Acoustical array with multilayer substrate integrated circuits does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Acoustical array with multilayer substrate integrated circuits, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Acoustical array with multilayer substrate integrated circuits will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3076722