US3636349A

US3636349A - Continuous orbit panographic x-ray

Info

Publication number: US3636349A
Application number: US6065A
Authority: US
Inventors: Jack Herman Faude; Henry Hollman
Original assignee: Pennwalt Corp
Current assignee: KEYSTONE X-RAY Inc
Priority date: 1970-01-27
Filing date: 1970-01-27
Publication date: 1972-01-18
Anticipated expiration: 1989-01-18

Abstract

X-ray apparatus for taking panoramic radiographs of structures, such as teeth, arranged in an arcuate line without shifting the subject. The X-ray source and film carrier are mounted on a common support which is adapted to revolve about the subject while the axis of revolution is driven in an arcuate path located within and substantially concentric with the arch of the structures''curvilinear configuration.

Description

United States Patent Faude et a]. 1 Jan. 18, 1972 4 TIN RBIT PANQGRAPHIC 2,798,958 7/1957 Hudson et a] ..250/6l.5 [5 1 UOUS 0 3,045,118 7/1962 Hellman et al. .....250l6l.5 3,536,913 10/1970 lrluchel ..250/6l.5 [72] Inventors: Jack Herman Fnude, Brooklyn; Henry Hellman, Sea Cliff, both of NY. Primary Examiner-William F. Lindquist Attorney-Carl A. l-lechmer, Jr. and Stanley Bilker [73] Assignee: Pennwalt Corporation, Philadelphia, Pa. [22] Filed: Jan. 27, 1970 ABSTRACT [21] APPL 0 5 X-ray apparatus for taking panoramic radiographs of structures, such as teeth, arranged in an arcuate line without shifting the subject. The X-ray source and film carrier are mounted [52] US. Cl. ..250/6l.5, 250/50, 250/65 R, on a common suppen which is adapted to revolve about the 250/70 subject while the axis of revolution is driven in an arcuate path [51] Int. Cl. ..G01n 21/00, H01 1 37/00 located within and subsmmiauy concentric with the arch of [58] Field of Search ..250l50, 52, 61.5, 65 R, 70 the stmcmms'cuwflinear configuratiom [56] References Cited 8 Claims, 10 Drawing Figures UNITED STATES PATENTS i 9 m V W 0 V I in m 1 I I Smathers "250/ 5 PATENTEUJAN18|972 3.636.349

SHEET 1 BF 4 INVENTORS JA CK H. FAUDE HENRY HOLL MA N ATTORNEY PATENIED mm 1972 3.636349 sum 2 or 4 INVE'N 70/?5 JA CK H. mun: HENRY HOLLMAN PATENTEnJAmm I 3,636,349

sum 320E 4 INVENTORS JACK H. FAUDE HNRY HOLLMAN ATTORNEY FIG. 8 7/3 IN VE N 70/?5.

.m CK H. FA u0 HENRY HOLLMAN A r TOR/VEY CONTINUOUS ORBIT PANOGRAPIIIC X-RAY This invention relates to X-ray apparatus for taking panoramic radiographs of parts and structures which arranged within a subject along an arcuate line, for example, the teeth, the jaws, the skull. More particularly, this invention relates to radiographic apparatus for taking full mount X-rays by means of a film plate located outside the mouth, all without shifting the patient during the exposure scanning process or without making abrupt position shifts of the apparatus itself to accommodate for the complex arch of the teeth. I

In prior U.S. Pat. No. 2,684,446 to Paatero, there is shown a radiographic process in which the patient himself is rotated about an imaginary axis passing axially through his body. This earlier construction not only encountered the distinct psychological problem of moving the patient himself or suspending him in awkward positions, it also caused'the projection of the exposure line to pass through adjacent overlapping parts thereby causing distortionand shadows.

In U.S. Pat. No. 2,798,958 to Hudson et al., there is shown a radiographic apparatus in which the patient remains fixed while the X-ray source and film plate located outside the subjects body are rotated about the subject. The film plane is moved relative to the motion of the X-ray sourceand relative to the position of the tooth being radiographed so that only the intended object tooth remains in focus during the scanning process while the teeth lying along another plane are blurred. However, the Hudson et al., system requires that the X-ray apparatus itself be shifted into two discrete positions whose corresponding axes are the opposite side molars in order to accommodate for the geometrically complex arch of the teeth. As a consequence, elaborate procedures are required to locate and displace the equipment of the discrete axes in addition to the problem of superimposing the left and right radiographs with respect to each other.

In prior U.S. Pat. No. 3,045,118 to Hollman et al., there is shown a dental radiographic apparatus which includes a laterally movable platform for holding the patient and shifting him from one side to the other in orderlto take successive X- ray scans of his left and right side dentures.

The present inventionconcems a dental radiographic apparatus in which there is no shifting of the patient whatsoever and in which a smooth and continuous traverse of the dental arch is performed to effect exposure along a line substantially normal to the curvilinear line of the teeth from a single setup position.

It is an object of this invention to provide a dental X-ray apparatus for taking a panographic exposure of the entire arch of the teeth in a single continuous extra-oral pass without shifting the patient and without requiring multiposition setup.

Another object of this invention is to provide a panographic X-ray apparatus for taking a continuous radiograph .of stationary structures arranged along an 'arcuate path within a body while always orienting the exposure axes substantially normal to the curvilinear line of the structures.

Still another object of this invention is to provide apanographic dental X-ray apparatus in which acontinuous radiograph is produced without being subject to interfering shadows of intermediate structures. 7

Yet another object of this invention is to provide a panographic dental X-ray apparatus in which adjustment can be made for variations in the dental arch.

Yet still another object of this invention is to provide a dental X-ray apparatus for taking extra-oral panographic radiographs of teeth of children or adults.

A still further object of this invention is to provide an extraoral dental panographic X-ray apparatus in which a continu-' ous radiograph of the entire dental arch is obtained with a single pass without shifting the patient or without being subject to obscuring influences of the spinal column structure.

Other objects of this invention are to provide an improved device of the character described which is easily and economically produced, which is sturdy in construction and both highly efficient and effective in operation.

With the above and related objects in view, this invention consists of the details of construction and combination of parts as will be more fully understood from the following detailed description when read in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a panoramic exposure dental X-ray apparatus embodying this invention.

FIG. 2 is an enlarged side elevational view of the X-ray source and film carrier yoke which is rotatable by a drive assembly embodied in this invention 'about an axis orbiting in a circular path.

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2.

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 3.

FIG. 5 is a view taken along lines 5-5 of FIG. 2.

FIG. 6 is a sectional view taken along lines 6-6 of FIG. 2.

FIG. 7 is a fragmentary side view of a modified form of the drive assembly for orbiting the axis of revolution of the yoke about an elliptical axis.

FIG. 7A is a fragmentary'perspective view of the modified form of the drive assemblyfor varying the arcuate configuration of the orbiting path. I v

FIG. 8 is a schematic view showing the circular path transcribed by the X-ray source-film carrier with respect to the arch of the teethwhen actuated by the drive assembly of the FIG. 2embodiment.

FIG. 9 is a schematic view showing the elliptical path transcribed by the X-ray source-film carrier when actuated by the modified drive assembly of FIG. 7. I

Referring now in greater .detail to the drawings in which similar reference characters refer tosimilar parts, the instant invention includes a frame, generally designated as A, a yoke B which supports an X-ray source C and a film carrier D in spaced disposition respect to each other, and a drive assembly,

generally designated as E, for orbiting the yoke about a rotating axis and revolving the axis about a curvilinear line which transcribes a closed loop path. In this manner, the X-ray source C and the film carrier D are caused to revolve orbitally about the head of a patient who remains fixed in position while the centerline of the orbit continuously moves through an arcuate path approximating the arch of the patients teeth.

Referring to FIGS. 1 and 2, the frame A is generally conventionalin construction and comprises a wheeled base 10 which carries electrical controls housed in a cabinet 12 and an upstanding column 14 on which is supported a vertically adjustable trolley or carriage 16. A horizontal boom l8 cantilevers outwardly from the vertically adjusting carriage l6 and bridges over the patient who is seated in a chair 20 usually on a stationary foundation with his head restrained in chinrest 21. A platform 22 at the end of the boom 18 supports the drive assembly E while a pedestal 24 mounted as a shroud over the platform carries an electric motor-gear reducer unit 26 which actuates the drive assembly E. The yoke B is suspended from an orbiting rotary shaft 28 depending from the drive assembly E.

Referring now to FIGS. 3 and 4, the drive assembly E comprises an upper rotatable casing portion 30 which carries an upstanding stem 32. The stem 32 is directly connected to the shaft of the motor drive unit 26 through coupling 34 so that the casing 30 rotates therewith. The lower periphery of the casing 30 includes an outwardly divergent flange 36 which is secured by circumfcrentially spaced,,screws 38 to a circular disk 40 which acts as a thrust race. The disk 40 is slidably supported at its outer margin upon a ball bearing lower race 42 which is secured upon an internal shoulder 44 formed within a lower housing 46. A dust ring 48 having peripheral threads complementary with internal threads in the lower housing 46 is threaded therein and urges upper ball bearing race 50 into slidable engagement with the upper margin of the disk 40. Affixed about an offcenter aperture in: the disk 40 and upwardly projecting therefrom is a sleeve bearing 52 which rotatably supports the yoke drive shaft 28. A cup 54 at the upper portion of the sleeve 52 has a ball bearing 55 which rotatably carries and supports the upper part of the drive shaft 28 while the medial portion of the shaft 28 is rotatably joumaled by bushing 56. Affixed by setscrews 58 to an intermediate portion of the drive shaft 28 adjacently below the bushing 56 is a spur gear 60. The spur gear 60 acts as a planetary gear in that its teeth intermesh with those of a stationary internal gear 62 which has a centrally disposed aperture. The internal gear 62 is secured to a retainer ring 64 which is affixed within the lower portion of the housing 46. The housing 46 itself is secured to the platform 22 above an opening therein by a plurality of screws 66 extending through a flanged portion 47. Thus, rotation of the upper casing 30 when driven by the motor drive 26 causes the shaft 28 to revolve in a circular path dictated by the path of travel of the eccentrically disposed sleeve 52. At the same time the planetary gear 60 because of its engagement with the internal gear 62 is caused to rotate about its central axis. Accordingly the shaft rotates in a predetermined relation to its path of revolution corresponding to the ratio of the diameter of the spur gear 60 to the diameter of the internal gear 62.

The yoke B includes a bracket 70 from which both the X- ray source C and the film carrier D depend. A tubular member 72 is retained in the bracket and holds a mount 74 at its terminus for pivoting the X-ray tube C about a horizontal axis 76 or about an axis normal thereto as defined by arm 78.

The film carrier D is supported on the bracket 70 diametrically opposite to the X-ray source C and is best shown in FIGS. 2 and 5. A shroud portion 80 defines a support for the camera casing 82 and includes a pulley 84 over which passes a cable 86 for actuating the film carriage 88. The front wall 90 of the casing 82 is made of radiopaque material, such as lead, and includes a vertical slit 92 centrally disposed therein. The rear of the casing 82 has a hinged door 94 for gaining access to the interior for loading and unloading the film cassette into the carriage 88. The cassette carriage 88 is suspended from a rail 96 by suitable rollers 98 to permit the film cassette itself to be carried past the exposure slit 92. The lower end of the cable 86 is attached at 100 to the left-hand end of the carriage 88 after passing over a lower pulley 102. A wire cord 104 from spring motor 106 biases the carriage 88 to the left. The cable 86 drives the carriage 8 8 and its film cassette from left to right as shown in FIG. 2 at a predetermined speed past the slit 92 in accordance with the following pattern.

Referring now to FIGS. 2 and 6, the upper end of the cable 86 is affixed to a cam 110 after passing over

idler pulleys

112 and 114. The cam 110 is rotatably supported on bearing 116 carried about the drive shaft 28 but is held stationary thereon by restraining arm 118. One end of the restraining arm 118 is affixed to the cam 110 while the other end has a pin 120 slidably engaging longitudinal slot 122 in a pivot limiting guide 124 secured to the underside of boom 18. The slot 122 accommodates for the arcuate path of travel transcribed by the drive shaft 28 but restricts the degree of pivotal motion of the cam 110 on the shaft. Accordingly, as the yoke B revolves about the patient's head, the cable 86 winds upon the grooved periphery of the cam 110 so as to draw the cassette carriage 88 past the slit 92 and successively expose the film.

Referring now to FIG. 8, the patient is seated in the chair 20 with his head restrained against movement by chin rest 21 while the X-ray source C and film carrier D are oriented along line I-I'. The position of the axis of shaft 28 substantially registers with point I such that the first exposure through slit 92 will be of rear molar T1. The shaft 28 of the yoke B rotates about its own axis while revolving smoothly and continuously through the arc defined by circle III'IX'XVI'. At the same time, the cassette carriage 88 moves the film successively past the slit to expose the respective teeth T1 through T16 inclusive to the beam of X-rays. It is worthy to note at this stage that the exposure of teeth T8 and T9 intermediate lines VIII- VIII and IXIX would require the X-ray beam to pass through the dense structure of the spinal column. Hence, the rate of travel of the drive shaft 28 may either be slowed down at the arc position of teeth T8 and T9 by appropriate controls of the drive motor unit 26 or the voltage to the X-ray tube stepped up, again by suitable circuitry to provide a greater intensity of the X-ray beam.

As may be seen from FIG. 8, the exposure of the teeth T1 through T16 takes place while the axis of the shaft 28 continuously revolves substantially through a semicircular are starting with point I' and terminating with XVI, the intermediate points representing zones rather than stops since the panoramic exposure occurs while the X-ray source C and the carrier D are making their sweep.

It is to be observed that the semicircular path defined by the movement through the points I'-VlIl'-XVI' falls within the arch of the teeth, for example an arc of 1%-1IICI'1 diameter to correspond with the complex arch of an average molar spacing of 2 inches. To accomplish such a traverse, the pitch diameter of'theplanetary gear 60 is Vii-inch and intermeshes with an internal gear 62 whose pitch diameter is 3 inches. As may be easily computed, such a ratio of pitch diameters produces slightly more than a full rotation .of the planetary spur gear 60 as it traverses through a half-circle of the internal gear 62. Accordingly, the direction of cxpos ure line I-I with respect to tooth Tl as well as the intermediate exposure lines through XVIXVI with respect to the corresponding teeth are always in phase as shown by the respective arrows; Note that the direction of the lines of exposureis approximately normal to the arch of the teeth without shifting the chair 20 in which the patient is seated, without shifting the position of the patient's head, or without shifting the X-ray apparatus 'itself once it has been set up.

In FIG. 9 there is shown an elliptical path of travel for the axis of the drive shaft 28 to correspond more closely with the arch of the teeth. In this manner, the lines of exposure I "-I through XVI-XVI" are oriented more perpendicular to the arch of the teeth thereby eliminating shadows created by overlapping teeth where the exposure lines would angularly pass through two or more adjacent teeth. The means for altering the path of travel is best shown in FIGS. 7 and 7A. Instead of connecting the yoke B directly to the drive shaft 28, the yoke is coupled to an adjustable eccentric or crank assembly E1.

The crank assembly E1 includes a slotted block 130 which is affixed to the drive shaft 28. Slidably supported in the slot of the block 130 is a slide member 132 which can be shifted by a screw 134. The screw 134 is threadedly engaged through the slide member 132 and axially restrained within the ends of the block 130 so that shaft 28A can be oriented eccentrically on either side of the axis of shaft 28 or in exact registration therewith. It is preferable to orient the slide crank E1 and its slot substantially parallel with the line of the tubehead C- and film carrier D. By such a construction, orienting the block 132 to the right of the center line of the shaft 28 will cause the shaft 28A to transcribe an elliptical path shown in solid lines whose major axis conforms with that shown in FIG. 9. Adjustment of the block 132 by screw 134 to the position where the axis of the shaft 28A is to the left of shaft 28 causes the major axis of the ellipse to be shifted as shown in dotted lines in FIG. 9. A vernier scale on the block and slide 132 denotes the degree of eccentricity whereby the path of revolution of the yoke B can be varied to suit the particular arch of the teeth being radiographed, for example to correspond with the narrow arch of children or to that of a wide-jawed adult.

What is claimed is:

1. X-ray apparatus for producing panoramic radiographs of structures arcuately disposed along a generally curvilinear arch comprising a frame, an X-ray source, a film carrier, means constituting a yoke supporting said X-ray source and said film carrier in spaced disposition with respect to each other along an exposure line passing through the arch of the arcuately disposed structures, and drive means in said frame for rotating said yoke about an axis in a predetermined rotary direction while at the same time continuously displacing said axis orbitally in the opposite rotary direction along an arcuate path located within the arch of the arcuately disposed structures without shifting said structures, said drive means including a stationary gear, a planetary gear in intermeshing engagement with said stationary gear and means for rotating said planetary gear with respect to said stationary gear.

2. The apparatus of claim 1 including means for adjustably suspending said yoke laterally with respect to said drive means wherein said drive means orbits the axis of rotation of said yoke about an elliptical axis.

3. The apparatus of claim 1 wherein said stationary gear comprises an internal gear.

4. The apparatus of claim 3 including an eccentric coupled to a shaft of said planetary gear.

5. The apparatus of claim 4 including means for continuously adjusting said eccentric with respect to the shaft of said planetary gear.

X-ray apparatus for producing panoramic radiographs of structures arcuately disposed along a generally'curvilinear arch comprising a frame, an X-ray source, a film carrier, a yoke supporting said X-ray source and said film carrier in spaced disposition from each other, drive means suspending said yoke within said frame so that a line passing between said X-ray source and said film carrier intersects the line of the curvilinear arch, said drive means including a motor, a stationary internal gear, a planetary spur gear in intermeshing engagement with said internal gear and rotated by said motor, and a support member coupling an intermediate portion of said yoke to said spur gear so that the support member will follow a generally curvilinear path described by the orbit of said planetary spur gear and at the same time rotate about the axis thereof, the gear ratios and diameters being so arranged that said spur gear will rotate substantially 360 about its own axis while transcribing a semicircular path within said internal gear, and means to move film in said film carrier transverse to the exposure line in response to orbital movement of said yoke.

7. The X-ray apparatus of claim 6 including means to adjustably displace the support member for said yoke eccentrically with respect to the axis of said spur gear whereby said curvilinear path may be varied to follow an elliptical configuration.

8. The X-ray apparatus of claim 7 including means for adjustably orienting the major and minor axes of the elliptical path about a polar axis.

Claims

5. The apparatus of claim 4 including means for continuously adjusting said eccentric with respect to the shaft of said planetary gear. X-ray apparatus for producing panoramic radiographs of structures arcuately disposed along a generally curvilinear arch comprising a frame, an X-ray source, a film carrier, a yoke supporting said X-ray source and said film carrier in spaced disposition from each other, drive means suspending said yoke within said frame so that a line passing between said X-ray source and said film carrier intersects the line of the curvilinear arch, said drive means including a motor, a stationary internal gear, a planetary spur gear in intermeshing engagement with said internal gear and rotated by said motor, and a support member coupling an intermediate portion of said yoke to said spur gear so that the support member will follow a generally curvilinear path described by the orbit of said planetary spur gear and at the same time rotate about thE axis thereof, the gear ratios and diameters being so arranged that said spur gear will rotate substantially 360* about its own axis while transcribing a semicircular path within said internal gear, and means to move film in said film carrier transverse to the exposure line in response to orbital movement of said yoke.