US2968302A - Multibeam focusing irradiator - Google Patents

Description

Jan. 17, 1961 w. J. FRY ETAL 2,968,302

MULTIBEAM FocusING IRRADIATOR Filed July 20. 1956 3 Sheets-Sheet 2 Jan.17,`1961 WJ. 'FRY Em 2,968,302

MULTIBEAM FOCUSING IRRADIATOR Filed July 20, 1956 5 Sheets-Sheet 5 United States Patent C MULTIBEAM FOCUSING IRRADIATOR William I. Fry and Frank I. Fry, Champaign, lll., assguors to University of Illinois Foundation Filed July 20, 1956, Ser. N0. 599,054

8 Claims. (Cl, 12S-24) This invention relates to an ultrasonic radiator, subsequently designated by theword irradiator," and more particularly to focused multibearn irradiators, having a plurality of individually focusable sound heads whose focal regions can be brought into coincidence by adjustment of the various heads. Such irradiators are especially suitable for use of practicing the method of treating living tissue as disclosed in our co-pending application for patent, Serial No. 554,607, tiled December 22, 1955.

Ultrasound can be focused by single or multiple lens systems, by reiiector systems, or by a combination of both. The size of the focal spot or region in such a system is determined by the wave length of the sound, the focal length of the focusing system and the aperture of the focusing arrangement. For the production of deep-seated lesions in living tissue, such as the brain, as well as for the treatment or observation of such tissues, it is often desirable, particularly for some positions in the brain, to use multiple focusing beams rather than a single beam. Focused multiple beams of the same convergence angle have an advantage because the skull bone must be removed before treatment of such tissues by ultrasound and in many instances it may be easier to prepare surgically an opening for admitting a number of focused individual beams than it would be to prepare, that is, remove enough bone to admit a single large beam. Furthermore, it may be easier to produce changes in the tissue at various positions inthe brain by an arrangement of multiple beams in that the number of beams used can be chosen to t the particular situation.

Accordingly, this invention provides a focused multibeam ultrasonic irradiator. The illustrated instrument utilizes four individual beams, although the number is not critical, emanating from four heads, each of which may be individually adjusted and each beam of which is produced by a vibrating element, focused by a lens placed in front of the element. There is also incorporated a pointer provided with suitable adjustments which enable its tip to be brought into coincidence with the focal region of the four beams when the transducer is producing sound in a medium such as water. This pointer is also retractable without disturbing the adjustments of the four heads and may be returned to its coincidental position to provide a reference or zero point for positioning the irradiator with respect to the tissue to be treated, such as the brain. The pointer is thereafter retractable without disturbing the setting of the four heads and is retracted during irradiation.

A more detailed description of one embodiment of this invention will now be given in connection with the accompanying drawings in which:

Figure l is a front elevation of a four beam focusing irradiator with one (the front) head removed;

Figure 2 is a top plan view;

Figure 3 is a fragmentary section, taken along line 3--3 of Figure 2; and

Figure 4 is a vertical section taken along line 4-4 f Figure 2.

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The four beam instrument illustrated is suspended from a common carrier shown as the lower end of the tube or cap 10 by means of three arms 12 fastened at their upper ends to a plate 14, secured to a disc 16 which in turn is secured to tube 10 by screws or any other suitable means (not shown). At their lower ends arms 12 are secured by screws 13 to four brackets 18, each of which is fastened to the collars 20 of two adjacent heads of the group of four heads, as is more clearly shown in Figures 1 and 2. The four collars 20 are thus carried by the tube 10 in a generally rectangular pattern and are arranged to support the four heads, inclined downwardly and inwardly toward a common Yfocal point.

The four heads are similar in construction and, therefore, only one will be described in detail. Each head has its own vibrating element 22, such as an X-cut quartz crystal, mounted within a cup-like housing 24, sealed at its upper end by plate 26, and sealing gasket 27, bolted to the outwardly extending flange 24 of the housing by bolts 28. Positioned within the upper portion of the housing and substantially filling the latter is an insulating block 29, to the lower face of which is secured a metal block 30 by screws 3l. The block is of lesser diameter than the housing 24, thus providing an annular channel 32 for receiving insulating oil. This channel may be lled through a duct 34 in block 29, said duct being closed by screw cap 36.

In front of, that is, below the crystal 22^is a planoconcave lens 40 positioned with i-ts plane face against or preferably slightly spaced from the lower face of the crystal. The lens may be made of polystyrene or any other suitable material, even metal. The space 41 between the crystal and the lens may be filled, for example, with degassed distilled water or castor oil. The crystal is sealed against the block 30 by gasket 42 on one side and against the intemed flange 24b of housing 24 by gasket 42a upon the other side, which gaskets also serve the purpose of cushioning the crystal. The lens is reltained in position by cap 43, secured to the lower end of housing 24 by screws 44. Gaskets 46 and 48 provide the necessary seals for the lens.

The outer face of the crystal, that is, the face adjacent the lens, is at ground potential and for this purpose a metallic foil connecting ring 50 is inserted between the outer face of the crystal and the lower intemed ange 24b of the housing 24. An annular collar 52 insures contact of the foil against the housing. The opposite face of the crystal, that is, its upper face, is at high potential and for this purpose, a second metal foil collar or ring 54 is placed between the upper gasket 23 and the metallic block 30 to insure good electrical contact between the crystal and the block. The gaskets 50 and 54 do not extend across the entire surface areas of the gaskets 42 and 42a and, therefore, do not defeat the sealing function of the gaskets. The sealing oil in the oil chamber between block 30 and the housing further insulates the block 30 and the crystal from the housing 24. The high frequency high voltage power to the crystal is provided through an electrical lead-in 56 concentric to the axis of the housing and having a sliding contact 57 with block 30. Lead-in 56 extends axially upward and is surrounded by a ground shield 58, the lower end of which is clamped between the plate 26 and the block 29 as shown in Figure 4.

The head thus far described is provided with certain adjustments to enable the individually focused beams to be brought into coincidence as a common point. For this reason, each head is loosely mounted within a collar 20 and is supported thereby for both a longitudinal movement along its axis to vary the phase of the emanatius sound waves in the coincdeqtal focal region. agg

also for angular or tilting movement to vary the position of the focal region of sound radiated from the crystal in a direction perpendicular to the beam axis.

With the foregoing in mind, the head thus far described is secured to the lower outwardly flanged end 60 of a sleeve 62 by screws 64. A filler block or guide 66 is placed between the flange 60 and the plate 26 being secured to the latter by screws 68. Block 66 serves as a lower guide for the insulating sleeve 70 which surrounds and is spaced from the connector 56; the connector 56, shield 58, and insulator 70 being coaxial.

The upper end of sleeve 62 is threaded at 74 and is threadedly engaged by a knurled adjusting nut 76 rotatable between upper and lower fixed collars 78 and 79 respectively. The latter are held in spaced relation, i.e. one upon each side of nut 76 by screws 80 and ferrules 81. The lower collar 79 is secured by screws 82 to the upper end of a second sleeve 84 coaxial with and surrounding sleeve 62. Sleeve 84 terminates in a lower outwardly extending ange 86. Sleeve 62 and flange 60 are guided for longitudinal movement along its axis by pins 88 xed in flange 60 and having a sliding tit in flange 86. Thus, sleeves 62 and 84 may slide axially one upon the other upon rotation of nut 76. The two sleeves cannot rotate with respect to each other because of pins 88. Accordingly, the crystal 22 and lens 40 can be adjusted axially for phase adjustment with respect to the other needs of the multibeam assembly.

As previously stated, provision is also made for tilting adjustment of the head. This is accomplished by providing a loose t between collar 20 and sleeve 84 to permit tilting movement of the sleeves within collar 20. A coiled spring 90 surrounds sleeve 84 and is placed under compression between the under face of fixed collar 79 secured to the upper end of sleeve 84 and the upper face of collar 20, secured to bracket 18. A plurality of adjusting screws 92, preferably three equally spaced, are threaded through collar 20 and engage notches formed on the upper face of flange 86. Thus, by adjusting the desired one, or ones, of these screws flange 86, and therefore, the entire unit can be tilted to the desired angle within the limits of the opening on collar 20.

The multibeam irradiator is provided with a pointer 100, adjustably supported, to enable its tip to be brought into a position coincidental to the common focal region of the four heads when the transducer is producing sound in a transferring medium, such as water. That is, after the four beams are brought into coincidence, the tip of the pointer may, through suitable adjustments, be positioned at the common focal region. For this purpose, the pointer is provided with two adjustments which move the tip in a plane perpendicular to the axis of the pointer, and with an additional adjustment which permits movement of the pointer along its axis in such a manner that the pointer can be retracted and/or lowered without disturbing the set adjustment for the lower position. In this latter position the pointer provides a reference or zero for positioning the irradiator with respect to the tissue to be treated, such as the brain. The pointer is in fully retracted position during irradiation.

Pointer 100 is mounted for vertical axial sliding movement in a holder 102 and may be locked in adjusted position by a set screw 104. This position may in fact be marked, so to speak, by a square collar 106 slidingly mounted on pointer 100 and retained in said position by a set screw 108. Holder 102 has an upwardly and laterally extending arm 110 the extremity of which extends to and lies between spaced ears 112 of a clevis 114, rigidly fastened to one of the four brackets 18 by one or more screws 116. Also secured to the same brackets 18 by one or more screws 118 is an arm 120 provided with a horiznntal bore 121 for slidingly and rotatably receiving a horizontal cylindrical projection 122 extending from the holder 102. An adjusting screw 124 extending through the bore 121 is threadedly received in the end of projection 122. Screw 124 also has an enlarged integral collar 126 which is engaged in the cap 128 which retains the screw against axial movement. Therefore, upon rotation of screw 124 the holder 102 and its pointer is moved horizontally in a plane, substantially perpendicular to the axis of the pointer.

The pointer may also be rotated about the horizontal axis of holder 102 as a center by means of two adjusting screws 130 threaded through the ears 112 and engaging the sides of the terminating end of arm 110. Accordingly, pointer can be tilted about the horizontal axis of holder 102 by adjustment of screws 130. Thus, the pointer can be adjusted vertically parallel to its axis and in two horizontal directions perpendicular to its axis so that it may be located exactly at the focal region of the four heads. Its vertical position may be marked, so to speak, by locating the collar 106 against the holder 102. When it is desired to retract the pointer, screw 104 may be released, the pointer raised, and then lowered again when desired to the pre-set position by merely lowering the pointer until collar 106 again engages 102. The collar being square and one llat side engaging the upper extending portion of arm 110, the exact position of the pointer, including its rotational position, is re-located. There is thus provided a retractable pointer for physically locating and identifying the focal position of the multibeam array.

The high voltage supply to each crystal 22 is through a lead 132 connected to the upper end of lead-in 56. The four leads 132 from the four heads extend upwardly and to a common connector (not shown) located within plate 14.

If adjustments to obtain equal acoustic outputs from the individual heads are not provided, the acoustic output reached in the focal region of the individual transducers may vary somewhat from one transducer to another for equal driving voltages. Therefore, i-t may be desirable to provide four adjustable condensers, that is, one in series with each of the individual crystals, to adjust the voltage across the individual crystals to realize equal acoustic sound levels from each of the crystals at the common focal point. These condensers are not shown but, if found desirable, the leads 132 would be connected to such condensers and not directly to the common terminal within the plate 14.

It will be obvious from the foregoing that changes may be made in the details of construction, in the number of heads, and in other respects without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

l. A focusing ultrasonic irradiator comprising a support, a housing carried by said support, a vibrating element in said housing for producing a beam of ultrasonic radiation, connections for supplying electric power to said vibrating element, a lens adjacent to said element for focusing Ithe beam radiated therefrom, an axially adjustable sleeve supported from said housing for carrying said vibrating element and said lens, means for adjusting said housing and sleeve relative to each other longitudinally with respect to said support in a direction along the axis of the beam for relative phase adjustment of -the beam with respect to an arbitrary reference, means for also adjusting said housing angularly within said support with respect to said axis for adjusting said beam in a direction perpendicular to the beam axis and a second sleeve surrounding said first sleeve, both sleeves being adjustable angularly within said support, said angularly adjusting means operating upon said second sleeve to produce said angular adjustmen-t.

2. A multibeam focusing ultrasound irradiator comprising: a plurality of supports, a common carrier for said supports, a housing carried by each of said supports, a vibrating element in each housing, connections for conducting electrical power to each of said elements, a lens adjacent to each of said elements for focusing the beams irradiated from said elements, means for adjusting each housing longitudinally with respect to its support in a direction along the axis of the beam produced by the element in said support for phase adjustment of the beam relative to other beams or to a reference, and means for adjusting each housing angularly within said support with respect -to said axis for adjusting the direction of each beam in a direction perpendicular to the axis of its beam whereby the focal points of said multiplicity of beams may be brought into coincidence.

3. A multibeam focusing ultrasound irradiator as dened in claim 2 wherein each of said elements and lens are supported in an axially adjustable sleeve supported from their respective housings and upon which said adjusting means operates to produce said longitudinal adjustments.

4. A multibeam foeusing ultrasound irradiator as dened in claim 2 wherein each of said sleeves is surrounded by a second sleeve, both sleeves being adjustable angu larly within said support, said angularly adjusting means operating upon said second sleeves to produce said angular adjustments.

5. A multibeam focusing ultrasound irradiator as defined in claim 2 wherein there is provided a retractable pointer carried thereby, and means on the housing supporting said pointer for axial movement toward and from the focal region of said beams, said pointer being tiltable in a direction perpendicular to the axis of said pointer.

6. A multibeam focusing ultrasound irradiator as dened in claim 2 wherein there is provided a retractable pointer carried thereby, and means on the housing supporting said pointer for axial movement toward and from the focal region of said beams, said pointer being adjustable horizontally in a direction perpendicular to the axis of said pointer.

7. A multibeam focusing ultrasound irradiator as defined in claim 2 wherein there is provided a pointer car- References Cited in the tile of this patent UNITED STATES PATENTS Harrison Sept. 11, 1945 FOREIGN PATENTS France Sept. 7, 1925 Switzerland Sept. 30, 1932 Germany Dec. 24, 1937 Switzerland July 1, 1952 OTHER REFERENCES 30 The Journal of General Physiology, vol. 26, 1942-3,

p. 183. (Copy in Division 55.)

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