US2891167A

US2891167A - Portable thulium x-ray unit with separable universal mounting means

Info

Publication number: US2891167A
Application number: US604051A
Authority: US
Inventors: Eugene W Coleman; Lawrence H Krohn
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-08-14
Filing date: 1956-08-14
Publication date: 1959-06-16
Anticipated expiration: 1976-06-16

Description

June 16, 1959 E. w. COLEMAN ET AL 2,891,167

' ,PORTABLE THULIUM x-RAY UNHl WITH SEPARABLE UNIVERSAL MOUNTING MEANS Filed Aug. 14, 1956 4 sheets-sheet 1 June 16, 1959 .w. COLEMAN ETAL 2,891,167 T PORTABLE THULIUM x-RAY UNIT WITH SEPARABLE UNIVERSAL MOUNTING MEANS Filed Aug. 14, 1956 4 Sheets-Sheet 2 UNIT EUGTNF VY. COLEMAN LAWRENCE fr. /fHO//V June 16, 1959 E. w. coLEMA E1' AL 2,891,167 PORTABLE THULIUM x-NAY UN w SEPARABLE UNIVERSAL MOUNTING M A s Filed Aug. 14, 1956 4 Sheets-Sheet 5 June 16, 1959 E. w. COLEMAN ET Al. 2,891,167

PORTABLE THULIUM X-RAY UNIT WITH SEPARABLE UNIVERSAL MOUNTING MEANS 4 SheetsSheet 4 Filed Aug. 14, 1956 WW m wmf w United States Patent -2,891,167 Patented June 16, 1959 [ice PORTABLE THULIUM X-'RAY UNIT WTH SEP- ARABLE MOUNTING MEANS Eugene W. Coleman 'and Lawrence H. Krohn, Ann

Arbor, Mich., assignors to the United States of America as represented by the Secretary of the Army Application August 14, 1956, Serial No. 604,051

Claims. (Cl. Z50- 105) (Granted under Title 35, U.S. Code (1952), sec. 265) The invention described herein may be manufactured and used yby or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to radiographic equipment, and more particularly to a` portable radiographic apparatus employing a radioactive isotype as the radiation source and suitable for human diagnostic radiography.

Containers presently used for portable radiographic equipment employing radioactive substances are awkward to transport and do not permit realization of the maximum attainment in portability due to the fact that the support stand for the container is integral with the container and usuallyincludes additional structural elements permitting orientation of the X-ray unit relative to the supporting stand. These additional structural elements add weight, and in the event the equipment is used extensively in the field, are subject to damage, making it dii'licult or impossible to operate the equipment. Some portable devices even employ small carts for transporting the radioactive material container which, as can be appreciated, does not provide the ultimate in portability, especially `for military eld use. A novel portable radiographic equipment described in application Serial No. 604,052, filed August 14, 1956, now abandoned, while overcoming many disadvantages of such equipment, requires a carrying and supporting frame of metal to protect the person transporting it against harmful radiation and requires a mechanical structure to orient the container relative to the support, all of which adds weight and bulk to a portable equipment. The instant device overcomes these difficulties by providing a novel combination of container andsupport for an improved portable radiographic equipment which permits orientation of the container with respect to the support therefor, not only in a `fixed arc `but also universal adjustment, without the need fo structural elements to accomplish `such orientation which permits'reduction in both bulk and weight of such equipment, making an ideal unit for emergency eld use for both military and civilian applications.

Research has proven that radioactive thulium may be used for `radiographing human subjects Without producing any harmful biological effects. While portable devices as in the `instant invention are not intended to replace the conventional X-ray tube type equipment insofar as definition and contrast are concerned, nevertheless it is `considered the instant improved portable radiographic equipment is a valuable adjunct in the field of diagnostic radiographic equipment because of the reduction inbulk and weight which enhance the portability of such equipment, simplicity of operation, and lack of dependence on electrical power sources such as in X-ray tube devices. i

In view `of the diiculties4 inherent in portable radiographic equipment as described above, it is a principal object of the instant invention to provide a portable radiographic equipment wherein orientation of the radioactive material container portion relative to its support may be accomplishedl without the use of structural'elements interconnecting the container and the support therefor to accomplish such orientation.

It is a further object of the instant invention to provide portable radiographic equipment wherein the radioactive material container portion may be readily separated from a supporting structure therefor without eiecting any mechanical disengagement.

it is a further object to provide portable radiographic equipment wherein the radioactive material container may be universally adjusted relative to a support therefor.

It is also an object of the instant invention to provide portable radiographic equipment capable of being safely transported and operated Vby a single person and which is of rugged construction for field use which embodies minimum bulk and weight.

i Other objects of the invention will become apparent from the following description, in which- Fig. l is a perspective view of the combination of the radioactive material container and the support therefor showing the manner in which the container is seated for universal movement in the support when the equipment is in use;

Fig. 2 is a central vertical sectional view of the lower portion of the radioactive material container showing the closure plug and supporting bracket in full lines when partially removed andin dotted lines` when fully removed; l

Fig. 3 is a view in elevation, showing `details of the handle of the radioactive material container;

Fig. 4 is a central vertical sectional View taken on the line 4,--4 of Fig. 3;

Fig. 5 is a plan view of a nut `included in the container structure;

Fig. 6 is an elevational view of the nut shown in Fig. 5;

Fig. 7 is a plan view of an internally threaded cap included in the container structure and engages the nut shown in Fig. 6;`

Fig. 8 is a central vertical sectional illustrated in Fig. 7;

Fig. 9 is a horizontal view partly in section taken on the line 5 5 of Fig. 4 showing the shutter in the closed position in full lines, and in the open position in dotted lines;

Fig. 10 is a vertical sectional view taken on the line 6-6 of Fig. 9;

Fig. 1l is a horizontal view taken on the line 7--7 of Fig. 4 with the shutter in the closed position;

Fig. l2 is a perspective view looking into the lower end of the upper portion of the radioactive material container;

Fig. 13 is a perspective view of the upper end of the lower portion of the radioactive material container showing the shutter structure with `the shutter in the closed position;

Fig. 14 is a plan view of the hinged bracket for carrying the'closure plug for the radioactive material container; and

Fig. l5 is avertical sectional viewtaken on the line 8 8 of Fig. 14.

The structure of the radioactive material container may be best described by reference to Figs. 3 and 4 wherein the container is shown as including an upper portion 1 and a lower portion 2. `The upper portion 1 is solid except for the centrally located recess 2 to receive the capsule 3 containing the radioactive material view of the cap 4 and the bore 5 for passage of the cable release 6. Ari` aluminum shell 7 cncascs the `.lead upper portion 1. The lower lead portion 2 is` also encased in an aluminum shell 8 except for a b rass disc 9 on Vthe outer face of lthe lead plug 10. The upper portion 1 and the lower portion Vto be described in greater detail hereafter.

2 are secured together by machine screws 11 recessed as at 13 to present a smooth surface. The machine screws are received in tapped holes 12 spaced around the meeting edge of the upper ,portion 1. The embodi* ment shown s` generally Vpear-shaped, but obviously other coniigurations'may be used provided that the lower portion 2 has the inwardly sloping contour shown as at '21 forga purpose which will Abe more fully described hereafter-.fV An' externally threaded nut 14 Vis Vcast integral with the upper portion 1 for engagement with an iiiternally threaded cap 15 provided with holes 17 to receive a Spanner wrench. The cap 1,5fhas an aluminum window 16 which closes the recess l2 but permits radiation-from the radioactive source material 4 to pass through. The recessed portion 17 communicates with a larger recess 18 which receives the shutter mechanism The upper portion 1 is further contoured at the meeting surface thereof as at 19 to receive Vthe raised area 20 on the meeting surfaceof the lower portion'2.

The lower portion V2 has anV inwardly tapered passage 27. The lead plug has a brass outer shell 22 enclosing the tapered portion thereof, and when the apparatus is not in use, the brass encased plug 10 is seated in the passage 27. The innermost end of the passage 27 Vis sealed by a thin metallick plate 23, such as aluminum or other metal having similar properties, which will not obstruct radiation when the shutter mechanism' is operated to permit emanations to pass through the passage 27. The brass encased lead plug 10 is secured by flathead machine screws 24 to a'bracket 25 by which the plug 10 may be droppedout of the passage 27 a short distance and then rotated about the hinge 26, as shown in Fig. 2, to completely open the passage 27. The hinge 26 includes a U-shaped yoke 28 secured by machine screws 29 to the lower portion 2, and the bight portion 28'V thereof abuts the peripheral edges of both the upper and lower portions 1 and. 2, respectively. The upstanding parts 30 of the yoke 28 are provided with holes 31 to'receive the hinge pin 32 which is maintained in position by means of a snap ring 33 which seats in a groove 34 in the end of the `hinge pin 32. The end of the bracket 25, which engages the hinge pin 32, is provided with an elongated slot 35 which, when the bracket 25 is released by the key 36, permits the bracket 25 to drop vertically iirst before being rotated when it is desired to remove the plug 10. The bracket has an elongated through slot 37 and an elongated recess 38 at right angles thereto. When it is desired to remove the plug 10, the key 36 is lifted slightly against the pressure of spring washer 39 and rotated 90 degrees to permit the key 36 to pass through the slot 37 allowing the bracket 25 to drop and be rotated. When the plug 10 is in the closed position, the key 36 is rotated to be at right angles to the slot 37 and held by the pressure of the spring washer 39 in the recess 38. The shank portion 40 of the key 36 abuts on arresilient cushion 41 seated in a recess 42in the lower portion 2. A'at washer 43 is positioned between the upset end of the shank portion 40 and the spring washer 39. A plate 44 is secured in any suitable manner to the lower portion 2 and provides a seat for the spring` washer 39.

A part of the aluminum shell 7, forming the apex 45 of the upperl portionr 1 of the'containenris of elongated configuration with the principal axis thereof normal to thev center line'about which the container is symmetrical. The apex 45 has a bore 46 therethrough which has an expanded portion47 adjacent one end of the bore 46 to receive aspring 48. A pin 49 passes through the bore 46 and has a bolt 50 secured in one end thereof and coactsV with the spring 48 to maintain a bail or handle 51 `in la 'desired position.

Reference is no w made to Figs. 9-13 for a description of theV shutter mechanism which is located on the raised area 20 of Vthe lower portion 2 and received in` the recess 18 when the upper and lower portions 1 and 2, respectively, are in assembledV condition. The shutter 52 is mounted on a bearing 53 carried by a stud 54 secured in the raised area 20` on the lower portion 2. A shde strip 55 is also secured to the raised area 20 on the lower portion 2 beneath `the shutter 52 by pins 56. The arcuate travel of the shutter when moving from the closed to open position or vice versa vis limited by the pins 56. The shutter 52, which may be Vbrass or other suitable material, has a gold insert 57 cast in the shutter and pressed to prevent escape of radiation when the shutter is closed. An anchor pin 58 is also secured in the raised area 20 in a location relative to the shutter 52 to permit the cable release 6 when secured in the bore 59 through the anchor pin 58 to be aligned with an edge 6@ of the shutter. Operation of the cable release 6 by means of the cable release button 61 will move the shutter 52 in an arcuate path, as shown inV dotted outline in Fig. 9, against the tension of a spring 62 which is carried by a stud 69. One arm 63 of the spring 62 is seated in a slot 64 in the edge 65 of the shutter 52, and the other arm 66 of the spring 62 is secured in the post 67. The shutter is provided with a projection 68 on the edge to prevent the cable release wire from getting out of contact with the shutter 52.

A particularly novel feature of the structure of the instant invention resides in the 4adjustment of the radioactive material container relative to its support. The tripod support is shown in Fig. l and comprises a generally ring-shaped memberv o'r collar 70 to which telescoping legs 71 are secured as shown in Fig. 2.

The member 70 isgnot continuous in order to permit the bracket 25 to be dropped when it is desired to take a radiograph. it is to be understood that other types of adjustable legs andmeans of fastening them to the member 78 may be practiced without departing from the scope of the invention. The size and exterior coniguraJ tion of the lower portion 2 of the radioactive material container coact with the ring-shaped member 7dv to permit universal adjustment of the container relative to the support. Reference to Figs. l and 2 illustrates the manner in which the inwardly sloping configuration of the exterior surface of the lower portion 2`is seated with in the ring-shaped member 70 and coacts therewith to permit the universal adjustment of the containerrela tive to'the support, and for rapid setting up and dismantlingrof the equipment without benefit of mechanicai components interconnecting the container and its sup`J port. It is obvious that the universal movement of the' container andthe support is limited` by the bracket 25, and in operation the hinge 26 is aligned with the open" end of the ring-shaped member' 70. Such economy of parts adds to the portability and provides a considerable' reduction in bulk and weight of the equipment which is important for iield use. Y

When it is desired to operate the equipment, the sup port tripod legs are adjustedto the desired subject-toh source height and position and the` radioactive material container is seated on the ring-shaped member 70 and oriented to the desired position relative to the support. The container may be tilted in the ring-shaped member 70 by virtue of the inwardly sloping sides of the exterior surface of the lower portion 2. The position selected will be maintained since the general conical shape of the container places the center of gravity adjacent the base of the container. Upon selection of the proper position, the passage 27 may be opened by rotating the key 36 to permit passage through the slot 37 so that the bracket 25 carrying the plug 10 may drop and be rotated to remove the plug 10 from the passage 27.l A radiograph may then be taken, using either conventional X-ray film or a self-contained cassette 72 by pressing the cable release button 61 and holding it forthe time required for the exposure. The self-contained type cassette which forms nopart of the present-invention, may be one wherein the developer and Stabilizer are components: of the film packet, for example, as in the Polaroid method of rapid processing by means of individual capsules of combined gelatinous developer and stabilizer which are integral parts of the film packet. The self-contained cassette permits rapid processing of radiographs and is especially desirable for field use. Where available, conventional X-ray film holders and methods of developing radiographs may be used. If intensifying screens are used, the screen is inserted next to the sensitive paper and the entire assembly placed in a film holder. Following exposure, the screen is removed and the paper processed either by the conventional method or by the Polaroid method.

Vln one embodiment of the invention, the radioactive material container measured 5% diameter at the base and, including the bail, was 61%5 high and weighed about pounds. The weight depends upon the amount of :shielding required for the radioactive source. If the source is free of radioactive contaminants, the dose rate is low and less shielding is required than when the contaminants are present.

The radioactive source 4 in one embodiment of the invention was a right cylinder of thulium metal 4 mm. in diameter and 4 mm. high. weighing 400 mg. The source 4 was encapsulated in an aluminum container or capsule 3 and secured in the recess 2. The radioactive source used in the instant invention is an isotope of thulium, thulium-170, which is obtained by activating naturally occurring thulium-169 by neutron bombardment. Since the half-life of the radioactive source, for example thulium-170, as used in one embodiment, is 129 days, replacement of the source 4 will be required. Such replacement may be accomplished by methods Well known in the art which prevent personnel from being subjected to harmful radiation. l

Isotopes, such as thulium-170, used in the instant device, should have the following characteristics to be useful for human radiography: (a) the majority` of the emitted photon energy should lie in therange of approximately 50 to 100 kev. since `these energies produce maximum contrast on lrns; (b) the specific activity (curies/ gram) should be sufficiently high so that a source size approximating a point will produce maximum definition; and (c) the physical half-life should be sufficiently long lso that the source will be `useful for reasonable lengths of time. With facilities presently available, higher activity per unit Weight is attainable, thus permitting a closer approximation of a point source without a decrease in dose rate. The focal spot of the source in one embodiment was 4 mm. Reduction to 2 mm. would produce considerably better definition in the radiographs. The use of higher activity and more pure thulium would improve the ratio of hard radiation to sof radiation in the beam. In the 4 mm. source, the activity in the top of the source cylinder contributes little radiation of the energies desired, 50 to 100 kev., since photons of this energy are absorbed before they can penetrate the thickness of the source. The hard bremsstrahlung produced by beta particles liberated in this area, however, is able to penetrate and contribute to the diffuse fogging, lack of contrast, of the ilm.

Thulium-l70 decays with the emission of beta particles having peak energies of 0.84 and 0.97 meV., and 84 kev. gamma ray photons. Associated with the decay is an internal conversion electron which results in the emission of 52 kev. ytterbium X-ray. In small samples these radiations would presumably be the principal ones of importance. In large sources the bremsstrahlung, or radiation liberated by deceleration of beta particles, must be considered. The principal penetrating radiations from thulium-170 consists of an 84 kev. gamma ray and a 52 kev. X-ray. In large samples, however, self-absorption tends to lower the output of these radiations and the brems'strahlung produced by deceleration of beta particles in either the container or the source of material itself becomes important. Both these factors tend to alter the spectrum of radiation energies and the resulting radiation differs: considerably from that obtained in small samples. Absorption measurements made to obtain a rough estimate of the spectrum, :indicated that an appreciable portion of the radiations possessed energies in excess of 10() kev., and that the softer radiations, below 100 kev., were present in far smaller quantities than would be expected from simple consideration of the decay scheme of thulium-170. Presumably this latter result was due to self-absorption of much of the radiation by the source material. The hard component was considered to be due to bremsstrahlung and to a source contaminant thought to be tantalum-l82 which complicates the `shielding problem because of the high gamma radiation, and interferes to a slight extent with the production of radiographs.

Measurements of the intensity of the radiation output of one embodiment of the invention were made using Victoreen ionization chambers. Repeated determinations indicated an output `of 6.8 r./hr. at one foot and a total curie strength of about cur-ies.

Since paper X-ray pictures presented certain advantages over transparencies for field use, radiographs taken under simulated field conditions with the device of the instant invention were made with radio-sensitive paper rather than film.. For most pictures the source was operated at an lS-inch source-to-subject distance. Exposure times of 12 to 19,0 seconds, depending upon intensifying screen used, thickness of tissue, etc., have proved satisfactory for most objects. The dosage of radiation delivered by exposures of these durations Varied from 10 to 160 mr. which corresponds favorably with the 40 to 220 mr. required from a conventional 80` kvp. X-ray machine for standard radiographs.

Because of the width of spectral energies obtained with the unit of the instant invention, it is possible to obtain radiographs of any portion of the body. Because of selfabsorption of soft radiations and the presence of external and internal bremsstrahlung, it appears likely that any high curie strength isotopic source will provide a wide spectrum of energies rather than monoenergetic beams. lf, by furtherrelinement of the radioactive source material, an approximately monoenergetic beam could be obtained, it would still bedicult to match the results obtained by the conventional X-ray machine where the relatively narrow spectrum of energies can be varied at will to give optimum results with various body thicknesses. While the unit of the instant linvention has been described using a radioisotope, thulium-169, other radioisotopes may be used with appropriate changes in shielding material dirnensions or a battery of isotopes of various energies may e incorporated in the unit and different ones used for different thicknesses of body parts without departing from the scope of this invention.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

l. The combination in a portable X-ray apparatus of a container for a radioactive source andd a separable support therefor, said container including upper and lower interfitting members of material impervious to emanations of radioactive material, said lower member having an inwardly inclined exterior surface, a. cavity in said upper portion, a radioactive source located in said cavity, a central conical passage lin said lower member aligned with said cavity, shutter means interposed between said radioactive source and said conical passage, a removable plug nonnally located in said conical passage, a bracket carrying said plug and hingedly secured externally of said container, means for locking said bracket to retain said plug in said conical passage, said support including a plurality of independently adjustable legs and a ring-shaped member xedly carried on said legs transversely thereof for engaging the inwardly inclined exterior surface of said lower member and coacting therewith to permit universal adjustment of said container relative to said support.

V2. A'portable X-ray napparatus comprising, in combination, a conically shaped container separable transversely of the longitudinal axis thereof into an upper solid member having a central cavity and a solid base member having a central conical passage and a raised central area, a radioactive source located in saidcavity, said upper member having a depression concentric with said cavityfor receiving saidraisedV central area when said upper and lower members are assembled, a recess in said upper member communicating with said cavity adjacent the raised area of said lower member when said upper and lower members are assembled, a iirst septum closing said cavity and a second septum closing the inner end of said conical passage, shutter means interposed between said first and second septums for controlling the passage of radiation from said radioactive vsource through said conical passage, a removable plug normally seated in said conical passage, a bracket carrying said plug and hingedly secured exteriorly of said container to permit free swinging motion of said bracket when removing said plug from said conical passage, means for locking said bracket to retain said plug in said conical passage, a bail secured externally to said container, said base member having an inwardly inclined surface, and an adjustable support including adiscontinuous ring-shaped member engaging the inwardly inclined surface of said base member permitting universal adjustment of said container relative to said support and free swinging motion of said bracket in a path normal to the plane of said ring-shaped member.

3. Apparatus as recited in claim 2 wherein said shutter means includes an arm pivotally secured to said raised area of said base member, said arm having an vinsert therein in registering position with said'cavity in the normalV Vversely of the longitudinal axis of the container, said upper portion having a cavity therein, a radioactive source carried in said cavity, a recess communicating with said cavity and extending horizontally outwardly from the open end of saidcavity, a depression formed in the upper portion forward of said recess and concentric with said cavity, said base poi-'tio' Vincluding a conical passage axially aligned with saidl cavity anda raised area on the meeting` surface thereof, said raised area engaging said depression when said upper and base portions are in assembled condition, shutter means pivotally carried by said raised` area for arcuate movement in said recess and interposed between said cavity and said conical passage for controlling the passage of radiation through said conical passage from said radioactive source, means for actuating said shutter means, a removable plug normally located in said conical passage, a bracket hingedly secured exteriorly to said container and carrying said plug to permit free swinging movement of said plug upon removal thereof from said conical passage, means locking said bracket in position to retain said plug lin said conical passage, and means `for carrying said container.

5. A portable X-ray apparatus comprising, in combination, a container for a radioactive source having separable upper and lower portions of material impervious to emanations of radioactivematerial, said lower portion having an inwardly inclined exterior surface, a cavity in said upper portion, al radioactive source located in said cavity, a central conical passage in said lower portion alignedA with said cavity, spaced upper and lower septum means interposed between said cavity and said conical passage and dimensionally greater than the adjacent opening of said conical passage, shutter means located between said spaced upper and lower septum means, a removable plug normally located in said conical passage, a bracket carrying said plug and hingedly secured externally of said container, means for locking said bracket to retain said plugin said conical passage and an adjustable support including an open ring-shaped portion for engaging the inwardly inclined exterior `surface f said lower portion whereby said container is universally adjustable relative to said'suppc'art.

` VReferences Cited in the le of this patent UNITED STATES PATENTS 2,551,491 Gilks May 1, 1951 2,684,447 Gilks July 20, 1954 2,743,372 Browne et al Apr. 24, 1956 2,764,694 vKinzer Sept. 25, 1956 2,772,361 Hiestand Nov.`27, 1956 Offner Feb. 12, 1957

Claims

1. THE COMBINATION IN A PORTABLE X-RAY APPARATUS OF A CONTAINER FOR RADIOACTIVE SOURCE AND A SEPARABLE SUPPORT THEREFOR, SAID CONTAINER INCLUDING UPPER AND LOWER INTERFITTING MEMBERS OF MATERIAL IMPERVIOUS TO EMANATIONS OF RADIOACTIVE MATERIAL, SAID LOWER MEMBER HAVING AN INWARDLY INCLINED EXTERIOR SURFAE, A CAVITY IN SAID UPPER PORTION, A RADIOACTIVE SOURCE LOCATED IN SAID CAVITY, A CENTRAL CONICAL PASSAGE IN SAID LOWE MEMBER ALIGNED WITH SAID CAVITY, SHUTTER MEANS INTERPOSED BETWEEN SAID RADIOACTIVE SOURCE AND SAID CONICAL PASSAGE, A REMOVABLE PLUG NORMALLY LOCATED IN SAID CONICAL PASSAGE, A BRACKET CARYING SAID PLUG AN D HINGEDLY SECURED EXTERNALLY OF SAID CONTAINER, MEANS FOR LOCKING SAID BRACKET TO RETAIN SAID PLUG IN SAID CONICAL PASSAGE, SAID SUPPORT INCLUDING A PLURALITY OF INDEPENDENTLY ADJUSTABLE LEGS AND A RING-SHAPED MEMBER FIXEDLY CARRIED ON SAID LEGS TRANSVERSELY THEREOF FOR ENGAGING THE INWARDLY INCLINED EXTERIOR SURFACE OF SAID LOWER MEMBER AND COATING THEREWITH TO PERMIT UNIVRSAL ADJUSTMENT OF SAID CONTAINER RELATIVE TO SAID SUPPORT.