US2937640A - Ultrasonic apparatus for medical treatment purposes - Google Patents

Description

1 9.3 m; 7' 7 5H xR 2,937,540 1 BR REFERENCE SUBSTITUTE FOR MISSlNG XR May 24, 1960 R. BASTIR 2,937,640

ULTRASONIC APPARATUS FOR MEDICAL TREATMENT PURPOSES Filed 00 25, 1952 l I l I l I l United States Patent ULTRASONIC APPARATUS FOR MEDICAL TREATMENT PURPOSES Robert Bastir, Erlangen, Germany, assignor to Siemens- Reiniger-Werke Aktiengesellschaft, Erlangen, Germany, a corporation of Germany Filed Oct. 25, 1952, Ser. No. 316,871

Claims priority, application Germany Nov. 2, 1951 17 Claims. Cl. 128-24) This invention is concerned with apparatus for the medical treatment of patients by the use of ultrasonic oscillations.

In such treatment, a radiating surface of a transducer which is excited by high-frequency electrical oscillations is placed in ultrasound conducting manner upon a body part of a patient for the purpose of irradiating into the patients body ultrasonic waves. The degree of the transmission of energy from the transducer to the body of the patient thereby depends upon the size or'extent of the portion of the radiating surface of the transducer facing the body of the patient in energy-conducting engagement therewith. Any relative motion between the transducer and the body of the patient usually causes alteration of the amount or extent of the transducer surface in energyconducting engagement with the body. Such relative motions or displacements therefore result in an alteration of the operative effect of energy transmission between the transducer and the patients body and therewith alteration of the amount of applied ultrasonic energy even if it is assumed that the high-frequency energy conducted to the transducer remains constant.

Known apparatus for medical ultrasonic treatment utilizing a transducer which is placed upon a desired body part to be treated employ a measuring instrument calibrated in watts, indicating the output of the electrical high-frequency generator which feeds the transducer. The reading of such instrument gives the operator an indication of the magnitude of the high-frequency output resulting in the transducer in the conversion from electrical to mechanical energy, but furnishes no indication as to the magnitude of the mechanical high-frequency energy which is being transferred from the transducer to the body to be treated.

The object of the invention is to provide an ultrasonic treatment apparatus of the indicated kind, containing a device for signalling to the operator displacement of the transducer relative to the body to be treated, that is, informing the operator in the event that thetransducer surface facing the body is only partially in sound-conducting engagement therewith.

Any alteration of the energy-transmitting surface of the transducer results in alteration of the radiation impedance thereof, and it follows, therefore, that such alterations of the energy-transmitting surface will result in alteration of the electrical resistance value in the oscillation circuit containing the transducer. The ultrasonic or ultrasound treatment apparatus therefore contains, in

accordance with the invention, a generator for producing high-frequency electrical oscillations, an ultrasonic transducer, fed from said generator, which has an energy radiating surface adapted for ultrasonic energy-transmitting contact with a part of a surface of the body to be treated, and an electrical device for supervising the electrical resistance value in the circuit containing the transducer and for effecting the operation of a signal when the supervised electrical resistance assumes a value corresponding to a radiation resistance value of the transducer which 2,937,640 Patented May 24, 1960 occurs when the transducer is only partially in energytransmitting engagement with the body to be treated.

The sound wave impedance of the human body corresponds essentially to that of water, and the signal device may therefore be so adjusted that it responds as soon as parts of the energy-radiating surface of the transducer border on a medium other than water. The adjustment may be made so that the device responds and actuates an optical or acoustical signal responsive to a small deviation from the feed-in radiation at full transducer surface in Water, due to the voltage drop occurring consequently at the transducer.

The supervision of the resistance value'of the circuit containing the transducer, by supervision of the voltage at the transducer presupposes that the output voltage of the high-frequency generator, feeding the transducer, remains constant. Assuming that this output voltage is regulable in steps or continuously, for the purpose of operating the transducer with energies of different magnitude, it is necessary to alter the response threshhold of the device for supervising the voltage at the transducer coincident with the alteration of the output adjustment of the generator, in such a manner, that the response threshhold is reached at a voltage value corresponding to the radiation resistance of the transducer when the energyradiating transducer surface is only partially in energyconducting engagement with the body to be treated.

In accordance with the invention, the device for supervising the electrical resistance of the circuit including trical high-frequency generator for altering the adjustable value of the signal-releasing means in such a manner that the signal-releasing means becomes with each adjustable generator output always operative responsive to identical diminutionof the sound-conducting area of the transducer relative to the body to be treated.

Details of the invention will appear from the description which will be rendered below with reference to the accompanying drawings. In these drawings,

Fig. 1 shows in schematic manner the elements of an ultrasonic treatment apparatus according to the invention; and

Fig. 2 illustrates a particularly advantageous principle circuit example for the apparatus indicated in Fig. 1.

The electrical high-frequency generator G in Fig. 1 feeds to the ultrasonic transducer S having an energyradiating surface which engages the body B to be treated through an interposed coupling medium. The voltage at the transducer S or an electrical value derived from this voltage governs the indicating device A which actuates a signal responsive to partial or complete severance of the transducer 5 from the body B. The signalling may be effected either at adequate firm coupling between the energy-radiating surface and the treatment subject or at insufficient coupling. To explain this somewhat more in detail, the signal may be operated at a time and for the time when the transducer is sufficiently or properly coupled with the body to be treated, and the signal will thus be effective for the duration of the sufficient or proper coupling. Cessation of the signal will therefore indicate to the operator that proper coupling is not present, e.g., due to a tipping of the transducer relative to the body in which case the radiating surface of the transducer borders partially or totally on air. The signal may also be caused to operate at a time when the transducer is improperly coupled with the body to be treated, thus informing the operator that the coupling is insufficient or improper for the intended treatment. The operator will thereupon manipulate the transducer to correct its position relative to the body and cessation of the signal will inform him that the proper adjustment has been made. The signal may be an acoustical signal or an optical signal. The first is preferred because it does not require constant attention and observation. The acoustical signal device may be constructed so that an alteration of the degree of coupling causes an alteration of sound intensity (volume) or a frequency alteration (pitch). The desired output of the generator G is adjustable by means of the output regulator R. The regulator R governs the response voltage of the indicating or signal device A, e.g., by connecting thereto a variable bias voltage in accordance with the adjusted output.

The generator G of Fig. 1 comprises the tubes Vl--V4 shown in Fig. 2 and their associated switching elements including the first self-excited oscillator stage comprising the tube V1 in an oscillating circuit with capacitors and resistors, a separation stage comprising the tube V2 to which is supplied the output of the first stage over a capacitative voltage divider T, and the final or output stage formed by the parallel-connected tubes V3 and V4. The oscillator is tuned to a fixed frequency by the ad justable capacitors in the first stage and the capacitor T, which constitutes the oscillating frequency of the ultrasonic transducer S (upper right hand corner of Fig. 2). The circuit of the separation stage acts inductively on the output stage. The transducer S is inductively coupled with the output stage.

The high-frequency current is held constant by electronic regulation with the diode VS, a voltage being used for this purpose which is proportional to the high-frequency current in the output stage. Such voltage is obtained at the capacitor C1 which is connected in the cathode circuit of the tube V4. The cathode direct current is conducted over a high-frequency choke D. i

The low high-frequency voltage resulting at the capacitor C1 is increased by the tuned series resonance circuit comprising the inductance L1 and the capacitance C3,-and is rectified in the diode V5. At the diode V5 is obtained a direct voltage which is negative to ground. This voltage is placed as a bias potential on the control grid of the tube V2.

The output is altered or adjusted by placing on the cathode of the diode VS a stabilizing positive potential corresponding to and in opposition to the negative bias potential. This regulation extends over a circuit including the left hand switch arm of the regulator R to the plate of the direct current stabilizer tube ST and maintains the high-frequency current constant even at considerable fluctuations of the network voltage, because the stabilizer tube ST also takes care to stabilize over obvious circuits the screen grid voltage of the regulation tube V2, the anode voltage of the oscillator V1, the negative grid voltage of the output stage V3 and V4 and the opposition voltage at the diode V5. The regulator R provides for adjustment of the output in different positions of the left-hand switch arm thereof. Variable opposing voltages are in these positions conducted to the cathode of the diode V5, which bring about corresponding alterations in the amplification of the tube V2.

A fraction of the voltage conductor to the transducer S is obtained over a capacitative voltage divider Sp, which is connected in parallel with the transducer, and such voltage is rectified in the diode V6. This diode receives from the output regulator R a positive bias potential over a 4 1y, when the regulator R is actuated to adjust'the output as described, the bias for the diode V6 is changed at the same time. The respective output adjusting circuits (left hand switch arm of regulator R) and the corresponding bias adjusting circuits for the diode V6 contain adjustable resistors P as shown.

If the voltage at the transducer S drops due to improper coupling with the body undergoing treatment, there will be no negative bias on the tube V7, and the plate current of this tube will energize the relay RS to cause actuation of the contact controlled by such relay so as to operate a signal device which may be connected circuit including the right hand switch arm thereof, such potential being of a magnitude just sutficient to accomplish the rectification of the voltage obtained at the voltage divider Sp at a time when the transducer S is in proper and sufiicient coupling with the body undergoing treatment. The negative voltage thereby resulting blocks the tube V7. The two switch arms of the regulator R are mechanically connected for common operation in the respective directions indicated by the arrows. Accordingat A to the circuit extending from the contact controlled by the relay RS. The signal device may be a suitable acoustical or optical device.

The output regulator R therefore varies or adjusts simultaneously two voltage values, namely, on the one hand, the opposition voltage for the diode V5 to adjust the generator output and the bias voltagesfor the diode V6, which controls the actuation of the signal.

The adjustable resistors P in the circuits extending from the various positions of the two arms of the regulator R also give the possibility of adjusting as desired the indicating or signal sensitivity for each adjusted output, that is, to determine the degree of coupling of the transducer S with the body undergoing treatment.

I claim:

1. In an ultrasonic treatment apparatus having an ultrasonic transducer forming a radiation surface for coupling engagement with an area of the surface of a body to be treated and having an electrical high-frequency generator for producing oscillations and circuit means for supplying said oscillations to said transducer, a signal device, an actuating device for said signal device, and means connected with said actuating device for monitoring the quality of coupling engagement of said transducer with said body, said monitoring means being sensitive to the radiation impedance of said transducer in engagement with said body, and regulating means for adjusting the output of said generator and for coincidentally adjusting the response sensitivity of said monitoring means so as to cause operative response thereof to alteration of the radiation impedance .of said transducer to operate said 'actuatingdevice so as to cause actuation of said signal device at instances when said coupling engagement between said radiation surface of said transducer and said area of the surface of said body reaches a value which is critical for the treatment in progress.

2. The apparatus as defined in claim 1,. comprising means controlled by said actuating means for causing operation of said signal device responsive to operative response of said monitoring means at instances when said coupling engagement of said transducer with said body is insufiicient for the treatment.

3. The apparatus as defined in claim 2, wherein said signal device comprises a signal lamp.

4. The apparatus as defined in claim 2, wherein said signal device comprises an acoustical device, said actuating device causing operation of such acoustical device by atfecting its frequency response.

' 5. The apparatus as defined in claim 2, wherein said signal device comprises an acoustical device, said actuating device causing operation of such acoustical device by affecting its volume.

6. The apparatus as defined in claim l, especially for applying medical treatment, comprising means for adjusting said regulating means to produce normal inoperated condition of said actuating device at a coupling of said transducer with said body which corresponds to proper coupling engagement thereof.

7. The apparatus as defined in claim 1, comprising circuit means for altering the operative response of said monitoring device responsive to alteration of the output of said generator.

8. The apparatus as defined in claim 1, wherein said monitoring means comprises a grid-controlled electronic tube, and relay means in the anode circuit thereof constituting said actuating means, the grid of said tube being governed by a voltage which is proportional to the voltage supplied to said transducer.

9. The apparatus as defined in claim 1, wherein saidmonitoring means comprises a grid-controlled electronic tube, and relay means in the anode circuit thereof constituting said actuating means, the grid of said tube being governed by the difference of two voltages, one of said voltages being a direct current voltage proportional to the high-frequency voltage supplied to said transducer and the other voltage being proportional to the adjusted output of said generator.

10. The apparatus as defined in claim 1, wherein said monitoring means comprises a grid-controlled electronic tube, and relay means in the anode circuit thereof constituting said actuating means, the grid of said tube being governed by the difference of two voltages, one of said voltages being a direct current voltage proportional to the high-frequency voltage supplied to said transducer, a diode for producing said one voltage, the cathode of said diode being biased by a direct current voltage which is automatically varied in accordance with the output adjustment of said generator, and the other voltage being proportional to the adjusted output of said generator.

11. The apparatus as defined in claim 1, comprising switching means governed by an electrical value which is proportional to the high-frequencfcurrent flowing through the transducer for controlling a stage in said high-frequency generator so as to maintain substantially constant the high-frequency current flowing through the transducer at an adjusted predetermined output of the generator.

12. The apparatus as defined in claim 11, wherein said generator comprises a discharge tube in the output stage thereof, and an impedance in the cathode circuit of said tube, the voltage drop at said impedance governing said switching means.

13. The apparatus as defined in claim 12, comprising a high-frequency rectifier for rectifying the increment of said voltage drop, and circuit means for conducting the resulting voltage as a regulation voltage to the grid circuit of a regulation stage of said generator.

14. The apparatus as defined in claim 11, comprising switching means for regulating the output of said highfrequency generator by connecting a regulating voltage thereto, and means controlled by said switching means for connecting an adjustable direct current voltage in opposition to said regulating voltage.

15. The apparatus as defined in claim 11, wherein said regulating means comprises a high-frequency rectifier and circuit means for deriving from said rectifier a 6 direct current voltage and for conducting said direct current voltage to said generator in opposition to the regulation voltage conducted thereto.

16. Ultrasonic medical treatment apparatus comprising an electronic high-frequency generator having an oscillator stage and a control stage and an output stage and having a transducer for contact engagement with a body to be treated, means for inductively coupling said control stage with the output stage of said generator, means for inductively coupling the output stage of said generator with said transducer. :1 control tube, a signal-control tube coupled to said transducer, a signal-actuating tube coupled to said signal-control tube, a regulating switch having two switch arms, circuit means for connecting one of said switch arms with an electrode of said control tube and the other of said switch arms with an electrode of said signal-control tube, contacts accessible to each of said switch arms, circuit means for interconnecting the contacts accessible to the switch arm connected to the electrode of said control tube with the respective stages of said generator, means for interconnecting the contacts accessible to the switch arm connected to the electrode of said signal-control tube with said output stage and with said control tube and said signal-actuating tube, a signal relay controlled by said signal-actuating tube, and a signal controlled by said relay.

17. In ultrasonic apparatus having a generator for producing high-frequency electrical oscillations and having a transducer and circuit means for feeding said oscillations thereto which transducer is adapted for ultrasonic conductive coupling engagement with a body to be treated for the purpose of irradiating into said body ultrasonic oscillations, an electrical device for monitoring the quality of the ultrasonic conductive coupling engagement of said transducer with said body, and means in said device for checking the electrical values in said feeding circuit to ascertain the magnitude of the radiation resistance of said transducer so as to determine said quality of the coupling engagement thereof with said body.

References Cited in the file of this patent UNITED STATES PATENTS 1,734,975 Loomis Nov. 12, 1929 2,283,285 Pohlman May 19, 1942 2,431,233 Erwin Nov. 18, 1947 2,444,349 Harrison June 29, 1948 2,467,285 Young Apr. 12, 1949 2,473,188 Albin June 14, 1949 2,517,948 Warren Aug. 8. 1950 2,543,248 Ledeboer et al Feb. 27, 1951 2,551,757 Mittelmann May 8, 1951 2,698,622 Martens 'Jan. 4, 1955 2,799,787 Guttner et al. July 16, 1957'

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