Measuring and testing – Vibration – By mechanical waves
Patent
1981-05-13
1983-10-11
Ciarlante, Anthony V.
Measuring and testing
Vibration
By mechanical waves
G01N 2904
Patent
active
044084927
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention concerns ultrasonic echoscopy. In particular it concerns the control of time gain compensation in ultrasonic echoscopy apparatus to improve the information content of echograms. This is particularly valuable in medical diagnosis using ultrasonic echoscopy, as it results in the more effective acquisition of relevant information, but the invention is not limited to this application of echoscopy.
BACKGROUND ART
To appreciate the nature of the present invention, it is helpful to first discuss the general principles of ultrasonic echoscopy (which is also known as ultrasonic echography, though strictly the two terms have different meanings). In ultrasonic echoscopy a short pulse of ultrasonic energy, typically in the 1-30 MHz frequency range, is directed into an object to be examined and any acoustic impedance discontinuities in the object reflect some of the energy. The reflected energy, or echo, is converted into an electrical signal and displayed on a cathode ray oscilloscope, a film, a chart, or in any other convenient form. This display, which provides information about the examined object to the user of the equipment, is known as an echogram.
The echogram may be either a one dimensional or a two dimensional representation. In both cases, the information is contained in the position and magnitude of the echo displayed. In a one dimensional display, the position along a base line is used to indicate the distance to the reflecting surface whilst the magnitude of the echo is displayed, for example, as a deflection of a base line or as an intensity change. In a two dimensional display, the position along a base line is used to indicate the distance to the reflecting surface as in a one dimensional display, and the direction of the base line is used to represent the direction of propagation of the acoustic energy. The two dimensional display is obtained by changing this direction of propagation of the acoustic energy and by instituting a similar, but not necessarily identical, movement of the base line of the display. The magnitude of the echo is displayed as for a one dimensional display (for example, as a deflection of the base line or as an intensity change).
The technique of ultrasonic echoscopy is used in medical diagnosis to obtain information about the anatomy of patients. The application of the technique has been described, for example, in the paper by D. E. Robinson in the "Proceedings of the Institution of Radio and Electronics Engineers, Australia", Volume 31, No. 11, pages 385-392, November, 1970, entitled "The Application of Ultrasound in Medical Diagnosis". As pointed out in that paper, ultrasonic echoscopy may be used to produce displays resembling anatomical cross-sections, and such displays have proved clinically useful when the desired information concerns the physical dimensions or the shape of organs, structures and the like. Ultrasonic echography has proved of particular value as a diagnostic aid in those areas of the body which contain soft tissue with little bone and air, particularly the abdomen and pregnant uterus, eye, breast, brain, lung, kidney, liver and heart. In general, the technique is considered to complement other techniques to provide a more complete picture of the patient's condition. However, particularly in pregnancies, ultrasonic echoscopy may be useful in place of X-rays as the latter may not give sufficient information, or may be dangerous.
Although ultrasonic echoscopy has uses other than as a diagnostic aid, this medical application of the technique provides a convenient example and will be used in the continuation of this description. In practice, a pulse of ultrasonic energy is transmitted into a patient in a known direction and echoes are received from reflecting surfaces within the body. The time delay between a transmitted pulse and the received echo depends on the distance from the transmitter to the reflecting surface and the distance information so obtained may be displayed in a suitable way for interpretation and clinical use
REFERENCES:
patent: 3690153 (1972-09-01), Matay
patent: 4057049 (1977-11-01), Hill
patent: 4140107 (1979-02-01), Lancee et al.
patent: 4228688 (1980-10-01), Sharpe
patent: 4305296 (1981-12-01), Green et al.
Kossoff George
Robinson David E.
Ciarlante Anthony V.
The Commonwealth of Australia
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