Shock wave source with increased degree of effectiveness

• US 4,840,166 A
• Filed: 03/26/1987
• Issued: 06/20/1989
• Est. Priority Date: 04/01/1986
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Reichenberger, Helmut, Schwark, Hubert, Naser, Georg
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US07/031,334
• Time in Patent Office: 817 Days
• Field of Search: 128/24 A, 128/328, 367/147
• US Class Current: 601/4
• CPC Class Codes: A61B 17/2251 characterised by coupling elements between the apparatus, e.g. shock wave apparatus or locating means, and the patient, e.g. details of bags, pressure control of bag on patient
• CPC Class Codes: A61B 2017/2253 using a coupling gel or liquid
• CPC Class Codes: G10K 11/02 Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Abstract

A shock wave source, especially useful for a lithotriptor, has a pressure source for the generation of a pressure wave impulse, a focusing device for focusing the pressure wave pulse, and a seal diaphragm for coupling the pressure wave pulse into the body of a patient, perhaps via a coupling body placed between the seal diaphragm and the patient. The seal diaphragm and the focusing device of the pressure source form a space which serves as a prepassage. The prepassage space is filled with a liquid substance which has a high B/A ratio and an acoustic impedance less than or equal to that of water. The advantage of this configuration is that the pressure wave pulse can be built up very rapidly in its course through the space. At a given point in the space, with the selection of the above-mentioned substances, as compared to water, a given minimum value of the quotient amplitude/build-up time of the pressure wave pulse can be achieved inspite of a reduced output amplitude at the pressure source. Consequently, the life expectancy of the pressure source is higher and less stress is placed on the patient by the acoustic energy. Thus, the degree of effectiveness of the lithotriptor is increased.

Claims

1. A shock wave source, particularly useful for a lithotriptor, comprising:

a pressure source for the generation of a pressure wave pulse having a direction of propagation;

a coupling body having an output adapted to be coupled to a body of a patient, said coupling body comprising material having an acoustic impedance value matched to that of the body of the patient;

a seal diaphragm for acoustically coupling said pressure wave pulse into said coupling body;

said seal diaphragm having a front wall disposed at a distance, in the direction of propagation of the pressure wave pulse, from the pressure source and in contact with said coupling body;

said seal diaghragm and said pressure source enclosing a space containing a substance having a B/A nonlinearity parameter value higher than that of water and an acoustic impedance value which is less than or equal to that of water;

said substance being acoustically coupled to both the pressure source and the seal diaphragm; and

said front wall of said seal diaphragm being shaped so as to cause focusing of the pressure wave pulse generated by the pressure source.

2. A shock wave source, particularly useful for a lithotriptor, comprising:

a pressure source for the generation of a pressure wave pulse having a direction of propagation;

a coupling body having an output adapted to be coupled to a body of a patient, said coupling body comprising material having an acoustic impedance value match to that of the body of the patient;

a seal diaphragm for acoustically coupling said pressure wave pulse into said coupling body;

said seal diaphragm having a curved front wall facing said pressure source disposed at a distance, in the direction of propgation of the pressure wave pulse, from the pressure source and in contact with said coupling body;

said seal diaphragm and said pressure source enclosnig a space containing a liquid having a B/A nonlinearity parameter value higher than that of water and an acoustic impedance value which is less than or equal to that of water;

said liquid being acoustically coupled to both the pressure source and the seal diaphragm; and

said front wall of said seal diaphragm being curved so as to cause focusing of the pressure wave pulse generated by the pressure source.

3. A shock wave source according to claim 2, wherein said liquid is selected from the group consisting of castor oil, ethanol, and benzene.