US 1156906 A
Description (OCR text may contain errors)
E. W. KELLY.
APPucATmN FILED Nova la. 1912.
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APPLICATION FILED NOV.18, 1912. 1,156,906. Patented 00u19; 1915.
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To all whom t may concern. v `\Be it known that I, EDWIN W. KELLY, a
'UNITED sTATEs PATENT OFFICE.
c i EDWIlIN W. KELLY, F PHILADELPHIA, PENNSYLVANIA. i
.'icitizen ofthe United States, residing .in the city of Philadelphia, countyof Philadelphia,
"and State of Pennsylvania, have inventedk ,certain new and useful Improvements in :Radiation-Shields, of which thev following `is a specification. F
It is the object of my invention to provide'means for shielding an operator from harmful radiations, such as X-rays. To this Aend I provide a box or inclosure for the V.source of radiations, such as an X-ray tube,
which is provided with lead or lother ray `'absorptive material graded or varied as to fits thickness, and therefore as to absorptive power, according to the locality of the absorptive' material with respect to the source. vof radiations, this being, in the case of an -1 X-ray tube, the focus spot onthetarget.
yBy my invention I am enabled to protect` :ran operator from the primary radiations,
y as well as secondary, tertiary and other radiations with relatively small amount of ray yapparatus is both cheapened and lightened weight.
absorptive materialwith the result that the For an illustration of one of the forms my invention may'take reference is to be had to the accompanying drawings, in which:
Figure 1 is a vertical sectional view through a shield box and its ray absorptive l'material, some parts shown in elevation. IFig-2 is a fragmentary front elevational l'view l of the apparatus shown in Fig.v 1. Fig. 3 is a horizontal. sectional view, taken -on the lines A-A of Fig'.v 1.
. "The X-ray tube X is supported by any suitable means within the boxB ofwood or any other suitable material. L The X-ray tube comprises the usualtarget or vanode a and cathode la, and vacum regulator 1'.
As vvwell understood in connection with X-rays these rays exist substantially entirely in a. hemisphere bounded by a plane embracing and coincident with the lplane of the face of target a, such plane being'fl'jepresented by a dotted line p,- Fig. 1. The rays in this hemisphere are substantially all primar or direct raysI and are the effective rays for are at the same time the most harmful to the operator.
The front of the box B has an aperture b and' registering with this aperture b is-the4 aperture' c in the plate or casting C of lead I Specification of Letters Patent.
`-ray operations or investigations and or terial.
.The thickness of the plate or casting C is a maximum where it is nearest the focus spot f on the anode or target a and diminishes in thickness in all directions, upwardly, downwardly, and laterally as indicated in Figs. 1, 2 and 3. The thickness at all points is however sufficient toibsorb `practically'all the primary rays impining upon the inside of the plate or casting and all secondary or tertiary rays that may impinge upon it. The thickness of the plate C at any point is a'function'of 'the distance of that point from focus spot f. The plate or casting C is secured to the any`other suitable ray absorptive mafront of the box or support B by any suit- ,able means such as screws '1, 1 Fig. 2. At its top and at the centermay be provided a lu y 2 as suitablemeansfor grasping the plate erably of lead, attached to thesebars' 8; and J9. As to the operation ofv the'shutter lor diaphragm it will be noted that each of the pivoted bars carries one-diaphragm element and that as the parallelograms are flattened "these members approach each other. v And Patented Oct. 19, 1915. Application filed November 18, 1912. Serial No. 732,055.
similarly the laterally disposed lugs 12 and -13 are provided upon the plate C, and .upon
these lugs are pivoted bars 14 and 15 pivoted I attheir outer ends to the bars -l'and 17,
constituting a p'arallelogram motion for moving'the diaphragm members 10 and llat-` tached to the bars V16 and 17 respectively. The bar 17 has an extension 2,0 and thebar 8 hasan extension 21 by which these paral-L 1 00 `lelogram motions may be actuated to move the diaphragm members to adjust the extent of aperture between for purposes of more or less 'restricting the fieldof the X-rays,
passing from the target a through the aperture c to the object under investigation.
On each side of the box B is provided a plate or casting D, of lead or other suitable y ray absorptive material. The upper edges of these plates D slant downwardlyv and back- Wardly from the front of the box as indiv cated by the dotted line in Fig. l, such edge v being substantially parallel With the plane of the target a'bt some distance back of or bove the plane of the target a shown in ".lhe plate C on the front of the box'extends upwardly beyond the plane of the tar-4 get a, asindicated in Fig. 1. -Above the plate C is ay relatively thin plate E, cf lead or other suitable absorptive material applied to the box B and extending over its top as shown in Fig. l, and on the sides above plates D. In this region Well back of the plane of the target a and in what may 'be called the inactive hemisphere, there practically are no direct radiations, but only secondary or tertiary radiations, Which are completely absorbed by the thin sheet metal E. Qn the bottom of the box B, as shown in ig. 1, is provided a sheet of metal F, of lead or other suitable ray absorptive material Which is preferably thicker than the sheet metal E because the plate F is Within the active hemisphere, but of such substantially uniform distance from the focus spot f that little or no economy Would be effected by changing its thickness with the variations in distance of its parts from the spot 7".
'lhe plate C has flanges 22 embracing the edges of the plate D, clearly shown in section in Fig. 3, and as these plates D are of varying thickness, (as explained, these flanges 22 extend from varying Widths of the plate C as indicated in Fig. 2. The box B may be provided with a removable or hinged cover Cr4 carrying the blocks of Wood or other material 23 through which extend;
the rubber or other insulating rods 24, 25 and 26 inclosing the conductors 27, 28 and 29 respectively, which connect With the positive terminal 30, the vacuum regulator terminal 31 and the-negative terminal 32 of the X-ray tube X.
Vand sides of the cover G, Within the active hemisphere, is a sheet J of lead or other ray absorptive material, of greater thickness y than the sheet H because disposed Within the active hemisphere. In the sheets H and J are provided apertures 33 and 34 around the rods 24, 25 and 26, these apertures being large enough to prevent the short circuiting,
of the high tension current from the conductors 27 and 29 to each other through the metallic sheeting. Due to these apertures however there is a possibility of escaping from .Within the box of some of the rays.
rlhrough the aperture 34 there Would escape some direct or primary rays Were it not for the fact that there is disposed in the path of such rays absorptive material such as the? sheets of lead glass 35 and 36 carried by the block 23 and of such size and so positioned as to prevent rays escapin through the aperture 34 through the Woo 23 and the cover G. The aperture 33 is in the inactive hemisphere Where the radiations are far weaker and in this case a single sheet of lead glass 37 is supported upon the upper block 23 of such dimensions and in such position as to prevent rays escaping through the aperture 33. For the sheets of lead glass 35, 36 and 37 other ray absorptive material may be employed as, for example, sheets of lead.
It Will be noted that the absorptive material of varying thickness, varies in thickness in a direction of a rectilinear ray from the focus spot f With distance from such focus spot, and simultaneously varies in thickness in a directionnormal to the surface of the support, as the flat outer surface of the box B.
From the foregoing description it is apxparent that 1 have 'provided means for shielding against primary, secondary, tertiary and lesser radiations by th`e employment of a relatively smally amount of ray absorptive material With resulting cheapening and lightening of Weight of the ray absorptive materialand of the apparatus as a Whole; the lightening of Weight being of further importance because of frequent need for moving the X-raytube and its shield as a unit.
What I claim is. y
l. The combination With an X-ray tube, of .a shield inclosing the same and comprising a mass of ray absorptive material varying in thickness between its inner and outer faces With distance from the focus spot of 'said tube and varying in thicknessv in a radial direction from said focusspot With distance from said focus spot'. i
2. r1he combination With. an X-ray tube,
. of a shield support having a surface varying in distance from the focus spot of said tube, a shield comprising ray absorptive material disposed upon said surface, said ray absorptive material having' different thicknesses `measured normally to said surface and different thiclmesses measured radially from the focus spot of said tube.
3. The combination with an X-ray tube, of a shield support having a surface vary- Aing in distance from the focus spot of said said member having an aperture member having a substantially dat surface,
a shield of ray absorptive material disposed upon said surface, said ray absorptive material diminishing in thickness normally to said'surface and radially from the focus spot of said tube with increasing distances from the focus spot of said tube.
5. The combination with an X-ray tube, ofv a shield therefor comprising a' support, ray absorptive material having an aperture in front of the focus spot of said tube, said ray absorptive material diminishing in thickness in a direction away from said aperture, asheet of ray absorptive material on said support in the active hemisphere in front of the focus spot, and a sheet of ray absorptive material of different thickness 0 and the ray-absorptive material back of on said support back of said focus spot.
6. The combination with an X-ray tube,"- .of a box inclosing the same, a sheet of conductive ray absorptive material disposed upon a wall of said box, said sheet having apertures conductors extending to the terminals of said tube through said apertures and spaced in said apertures fromsaid material, and lray -absorptive material interposed between said apertures and said tube. .7. The combination with an X-ray tube, of a conductor communicating with a terminal thereof, ray'absorptive material having an aperture through which said conductor passes, and ray absorptive material intervening between said aperture and said X-ray tube.
8. The combination with an X-rayv tube, of a substantially at shield member of ray absorptive material associated therewith, through which direct rays may be passed, said member diminishing in thickness in av direction. away'from said aperture, and a diaphragm of ray absorptive material supported on said member.
9. The combination with an X-ray tube, of a box inclosing the' same, a coating of ray absor tive materlal on the walls' of said box, thetickness-of said ray absorptive material diminishing with the distance of said material from the focus spot of said tube.
focus spot to the plane bounding said hemisphere.
1'1. The combination with an X-ray tube, of a shield therefor comprising ra -absorptive `mat erial inclosing said tube and disposed at varying distances from the focus spot thereof, said ray-absorptivematerial within the active hemisphere diminishing in thickness from the region nearest said focus spot to the plane bounding said hemisphere,
said plane being relatively thin and of substantially uniform thickness.
12. The combination with anX-ray tube,
of a box and its -cover, ray-absorptive material inclosing said tube carried by the' walls of said box, said walls being substantially flat, and said ray-absorptive material diminishing in thickness from the region nearest the focus spot of said tube to the plane bounding the active hemisphere.
13. The combination with an X-ray tube, of a box having front and sides inclosing said tube, the walls of said box being substantially dat, ray absorptive material dis-l posed upon the front and sides of said box, the ray absorptive material infront of sald box diminishing in thickness with distance from the focus spot of said tube, masses of ray absorptive material on the sides of .sald box and having edes slanting substantlally `parallel Awiththe ace of the target of ysaid tube, said last named masses diminishing in thickness with distance from the focus spot of said tube.
In testimony whereof I have hereunto aixed my signature in the two subscribing witnesses.
' EDWIN W. KELLY.
E. T. MGCALL, NELLIE EVANS.
presence of the