GB2348705A

GB2348705A - Ultrasonic device for the measurement of internal surface profiles

Info

Publication number: GB2348705A
Application number: GB9929197A
Authority: GB
Inventors: William Forrest Fagan; Michael Frederick Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-12-10
Filing date: 1999-12-10
Publication date: 2000-10-11
Also published as: GB9929197D0; WO2000034739A2; AU1577200A; EP1058594A2; WO2000034739A3

Abstract

The device consists of an ultrasonic probe 12 with multiple rings 13 of piezoelectric transducers combined with integral optical fibres (6, Fig.2) for viewing and illumination. A ball (11, Fig.3) and a guide tube (10) are also provided to permit the easy, fast and safe alignment of the body of the probe relative to the internal surface being contoured. Multiplexer units (16, Fig.5) are provided to reduce the number of electrical wire connections running the full length of the probe.

Description

2348705 Improvements in Ultrasonic Devices for the Measurement of Internal

Surface Profiles This invention relates to improvements in devices that use ultrasonic waves to measure the internal surface topography of structures.

Existing ultrasonic catheter probes are currently used in the investigation of the build up and the extent of plaque and calcium deposits in the arteries of patients who have coronary heart disease. The catheter employs a single ring of minature piezoelectric elements located around its circumference at one end of the probe that act as pulsed ultrasonic radar systems to measure the cross sectional profile of the arterial wall.

The improvements described here over the currently available catheters augrnent the catheter probe's capabilities by adding an optical system to the body of the probe to permit the direct illumination and viewing of the internal surface being measured for the purposes of alignment and safety. provided an optical transmission path exists. Another improvement of this invention incorporates a plurality of the rings of piezoelectric elements located along the body of the probe to measure the three dimensional surface topography of the inner suffice being tnemured without the nece"ity of mechanically timslating the probe to different longitudinal positions during the measurement process that can lead to citois if the probe nioves relative to the surface. The effect of these two innovations is to permit the more rapid, 2 easier., and safe use of the probe, in non-arterial Applications, such is'mi- Aivo measurements of the car canal and in the general measurement of the inner surfact shape of any cavity, v6id, tube or other internal structure both natural and artificial.

I - Specific embodiments of the 'invention will now be described by way of example with reference to the accompanying diagrams in which:

Figure I shows a block diagram of the measurement method where the electrical signals that contain the surface topography information of the internal surface being measured by the ultrasonic probe (1) are fed into a computer (2) which creates an image Me (3) of the surface topography that can then be displayed as a rendered 3D model on the monitor or exported in the required format for fin-ther processing such as a STL file for arapid prototyping system.

Figure 2 shows details of the ultrasonic probe combined with the optical system where the ring of piezoelectric ffmsdueet- elements (4). only- one ring being shovm here for clarity, is positioned on the outer surface of the probes body (5) The central glass rod relay lens orcoherent fibre optic bundle (6) transmits the image of the internalsurfaccbe measured to a TV camera -located- at lag the other end of the glass rod lefts. An incoherent fibre optic array (7) is wound around the glass rod lens or coherent fibre- bundle and directs light onto tlw surfact behrig rffeamd ftiff a light - 56iffrae opticdly- wapled t6 1 1 the incoherent fibre array at the other end of the probe.

Figure 3 shows how tim probe (8) can be- positioned carre-otly-with regpet'td'the surface being measured (9) in order that the probe does- not come into contact with any part of this surface that would generate bad data at the contact dria---. This- is- accomplished by means -of a guidilig tube (10) located- in- a bail- (11) that^ be constructed' in metalor plastic.

Figure 4 shows the probe (12) with a number of piezoelectric transducer rings (13) that are measuring the internal shape of a cavity (14). Each ring is comprised of a number of piezoelectric elements that emit and receive ultrasonic waves that act as minature pulsed radar systems giving a measure of the distance from the probe to the surface being measured. The electrical signals from all the elements in a sin le ring are a measure of the surface profile of the cavity in a plane defined by the ring of piezoelectric transducers (13) The resolution of the probe with respect to surface contour information is governed by the number of piezoelectric elements in a ring and by the number and the spacing of the transducer rings (13) along the longitudinal axis of the probe. The optical system described in Figure 2 can also be 'incorporated into this probe to aid in its correct positioning in the cavity being measured.

Figure 5 shows how the electrical signals from all the individual piezoelectric transducers (15) located on the probe described in Figure 4 are relayed through the body of the probe on their way to be processed by the computer.

F Use is made of a number of multiplexer electronic components (16) to reduce the number of signal wires coming from the transducers to manageable proportions in order to fit more compactly into the space available in the probe body. Each ring of piezoelectric transducers (15) has its own multiplexer unit (16) that transmits the multiplexed signals to a decoding unit (17) located at the outside end of the probe where the separated signals are then fed into the computer for processing.

1

Claims

1. An ultrasonic probe used to contour the shape of internal cavities comprising of a series of piezoelectric transducer rings located along the body of the probe and an optical system that is Integrated into the centre of the probe that utilises a solid optic relay lens or coherent fibre bundle for imagmig and an incoherent fibre bundle for illumination and that permits the illumination and viewing of the internal cavity for alignment and safety purposes, concomitant with the measurement process.

2. An ultrasonic probe as described in claim 1 without the optical system described therein but utili'sm'g the position information derived firom the piezoelectric transducers arrays to determine the optimum and safe measurement location.

3. A guiding tube and ball device to allow the correct external positioning of the probe relative to the internal cavity surface being measured.

4. The use of a series of multiplexer units built into the body of the probe described in claim 1 that allow all the electrical signals to be transmitted to and from every piezoelectric transducer located on all the transducer rings without the need for having individual wire connections running the full length of the probe thereby permitting the construction of a more compact probe body.