in fig2 is shown a main transducer 1 in the form of a spherical skull cap supported by a mount which allows it to move along three orthogonal axes x , y and z . this mount has been shown schematically , its construction being within the scope of a man skilled in the art . along the axis of the spherical skull cap is disposed an auxiliary transducer 2 of a generally cylindrical shape which passes through skull cap 1 and is fixed thereto . a pocket of water p is placed between the skull cap 1 and the surface s of the body of the patient , who is assumed lying flat on a horizontal plane . the skull cap 1 has for example a diameter of 200 to 300 mm and is formed from a large number ( 300 or 400 ) of piezoelectric elements 10 , 11 , etc . . . ( fig1 ) isolated from each other and juxtaposed so as to form a mosaic . these elements are metallized on both faces , one of the metallizations being connected to ground and the other to connections for energization by a main emitter 3 . this latter delivers an electric signal a ( fig3 ) formed of high frequency wave trains ( 500 khz for example ) of a relatively low peak power ( about 10 or a 100 watts for example ), but of a relatively long duration ( for example of the order of a second ) separated by time intervals of the order of 1 / 10 second , the time required for the echography device to form an image . it is then a question of operating conditions using substantially continuous emission for the treatment . such operating conditions may be obtained by means of emitters using power transistors . preferably , the elements of transducer 1 will be divided up into groups each energized by a separate emitter ( rectangle 4 symbolizing the assembly of these emitters ), the elements of each group being spaced apart in the same circular zone of the spherical surface . by adjusting the relative phases of the emissions , it is possible to modify the energy distribution in the focusing region of the ultra sonic beam . an input 31 to emitter 3 symbolizes an adjustment of the emitted power and an input 32 symbolizes an adjustment of the wave train duration . the focal spot formed in the center f of the sphere may , with this technique , be very small ( diameter of 2 or 3 mm for example ) and have a position which is strictly fixed for a given position of the transducer . in fig1 it can be seen that the auxiliary transducer 2 is itself connected both to a high frequency electric pulse emitter 21 and to a reception amplifier 22 followed by an analog - digital converter 23 , itself followed by a memory 24 . emitter 21 is synchronized by a pulse generator 211 which delivers 256 pulses during each of the successive time intervals of 1 / 10 second . to each of these time intervals corresponds a complete sweep of a given angular sector θ ( fig1 ) by the beam emitted by transducer 2 so the formation , in the sweep plane , of an image of the zone observed by the echography device . transducer 2 is advantageously of the type described in french patent applications number 80 16717 filed on the jul . 29 , 1980 for : &# 34 ; a sectorial sweep echography probe comprising two coupling liquids ,&# 34 ; and n . 80 16718 filed on the jul . 29 , 1980 for : &# 34 ; mechanical sectorial sweep echography probe &# 34 ;, that is to say that it comprises an oscillating piezoelectric element 200 controlled by a motor 201 , itself controlled by an electronic circuit which is shown symbolically by a rectangle 4 . this electronic circuit provides control signals for the motor 201 housed inside the case of the transducer 2 and is adapted so that a complete oscillation of the motor corresponds to the above defined duration for forming an image ( 1 / 10 sec .). in a first operating mode ( treatment and checking ) switch 210 is in position i as well as switches 212 and 33 . in position i of switches 33 and 212 , generator 211 is synchronized by a first output 41 of circuit 4 , and this latter is then adjusted , by means not shown , for generating at its output 43 connected to motor 201 signals having the wave form ( mt ) shown in fig4 . an image is swept then in 1 / 10 sec . and is followed by a time interval of 1 sec . during which the oscillating element 200 remains immobile , so that transducer 2 receives no echos . during the intervals between the sweep periods , a circuit 34 generates square waves of 1 sec . which serve for synchronizing emitter 3 whereas , during the sweep periods , a circuit 213 generates square waves of 1 / 10 sec . which serve for synchronizing the generator 211 . thus , in this operating mode , transducer 1 generates an ultra - sonic beam under substantially continuous operating conditions whereas the echography device forms an image every second in the intervals between the wave trains . at ( bt ) has been shown the wave forms of the signals then emitted by generator 211 . in a second operating mode ( locating ) with switch 210 in position i , switch 33 is in position ii , so that emitter 3 is not synchronized and the focused ultrasonic beam is not emitted . switch 212 is also in position ii so that generator 211 is synchronized by a second output 42 of circuit 4 and this latter is adjusted so as to generate at its output 43 signals having the wave forms ( mr ) shown in fig3 . the 1 / 10 sec . sweeps are then separated by time intervals of 1 / 100 sec . only and the images are formed from echos coming from the reflection of the pulses generated by transducer 2 . generator 211 delivers the signals ( br ). in a third operating mode ( checking the focal region ), switch 210 is in position iii , so that the emitter 21 and transducer 2 do not emit . switch 212 is again in position ii so that generator 211 is synchronized by the output 42 of circuit 4 and this latter is adjusted as in the second operating mode so that the 1 / 10 sec . sweeps are again separated by intervals of 1 / 100 sec . switch 33 is in position iii and consequently emitter 3 is now synchronized by the generator 211 which then delivers the signals ( br ). in this third operating mode , the echographic device is therefore formed by emitter 3 , transducer 1 operating for emission and transducer 2 operating for reception . the result is that an image of the zone of concentration in the focal region of the energy emitted by the transducer 1 is obtained . the echographic signals received at 22 in the first or third operating modes are , after analog - digital conversion at 23 , stored line by line in memory 24 , a writing addressing device 25 , controlled by circuit 4 , causing the respective deflection angles of the beam emitted and / or received by transducer 2 to correspond with the respective lines of the memory . a device 26 for rapid reading of the memory energizes the x and y deflection coils of a cathode ray tube 28 , so the brightness control electrode receives the corresponding contents from memory 24 , transformed into an analog signal by a digital - analog converter 27 . the practical construction of all the circuits described and shown is within the scope of a man skilled in the art . the control circuit 4 may for example comprise a one shot multivibrator delivering square waves of a duration adjustable to 1 / 100 s or 1s depending on the operating mode and circuits for generating increasing and decreasing voltages of a 1 / 10 s duration , triggered off by said square waves . in the locating operating mode , the operator searches for and localizes the zone to be treated . the display device is adapted , in a way known per se , so as to materialize on the screen of the cathode ray tube ( for example by means of a cross ) the theoretical position of the focal spot in the sectional plane shown , which plane passes through the axis of symmetry of transducer 1 . ( it is a question of b type echography ). the operator begins by moving transducer 1 along x , until the tumour appears clearly on the screen , then he moves it along y and z , until the cross coincides with the central region of the image of the tumour ( k , fig4 ). at this moment , the switches may be placed in position for checking the focal region : only this latter is then made visible on the screen , with a luminosity proportional to the corresponding energy concentration . thus a representation is obtained of what the distribution of the energy of the treatment wave will be , which allows the adjustments to be checked and perfected . during treatment , the apparatus only supplies one image per second , but this rate is sufficient for substantially permanently checking the position of the focal spot . it is clear that the apparatus described allows the evolution of the tumour to be checked after each treatment sequence . it is evident that different modifications may be made thereto and even according to other embodiments , without departing from the scope and spirit of the invention .
an article of manufacture which is used in medical treatment is a concave wave focusing device and a piezoelectric surface coupled to a target locating and treatment aiming ultrasound transducer which is located between the target and the surface and which scans the target to display a target image in coincidence with a visible indication of the focal point of the focusing device .