GB2296288A - Mount for a radiation shield - Google Patents

Abstract

A mount for a radiation shield comprises an assembly capable of attachment to the radiation shield, the assembly comprising a bearing member 18 retained in an accommodating bearing socket formed between two retaining members 8, 10, and engagement means 16 which retain the retaining members in operative positions in which the retaining members define the bearing socket, the bearing member being movable in the socket to provide for adjusting movement of the shield. <IMAGE>

Description

Title: Improvements in or Relating to Radiation Shields Field of the Invention This invention relates to a mount for a radiation shield, and to radiation shields in combination with said mount.

Background of the Invention Radiation is extensively used in medicine, for the purpose of diagnosis and/or therapy.

Repeated exposure to radiation is clearly undesirable, due to the well-documented risks to health.

Accordingly, it is known to use a variety of radiation shields to prevent unnecessary exposure to radiation of patients and/or medical staff. One type of shield comprises a sheet of protective material (typically leaded glass or a leaded plastics) mounted at the free end of a movable supporting arm, which allows the shield to be variably positioned in a plurality of different orientations for optimum protective effect.

An example of such a shield is disclosed in US Patent No. 4,923,162, which describes a radiation shield having a ball and socket type mounting. The ball is located in a socket formed between two ring bearing pads, which are positioned in an aperture in the centre of the shield. The bearing pads, with the ball member positioned therebetween, are clamped in place by two clamping members (one on each side of the shield) and retained by bolts. The degree of frictional engagement between the bearing pads and the ball member is varied by the user by means of an adjustable screw.

This arrangement involves a large number of components which are required to be assembled by the manufacturer and then transported, ready-assembled, to the purchaser.

Transport of the ready-assembled radiation shield and mount combination is costly and difficult as the combination is bulky and cumbersome.

Summary of the Invention In a first aspect the invention provides a mount for a radiation shield, comprising an assembly capable of attachment to the radiation shield, the assembly comprising a bearing member retained in an accommodating bearing socket formed between two retaining members, and engagment means which retain the retaining members in operative positions in which the retaining members define the bearing socket, the bearing member being movable in the socket to provide for adjusting movement of the shield.

The radiation shield itself is conveniently of the conventional type, comprising a substantially rectangular layer of leaded glass or leaded plastics protective material, typically with an inset cut into one corner.

The mount preferably includes a support arm, one end of which is formed with or attached to the bearing member. The support arm conveniently is formed with an angled off-set, the end of which is formed with or attached to the bearing member. The support arm is typically attached at the other end to other equipment or to a wall- or ceiling-mounted bracket.

Preferably the bearing member is substantially spherical, such that the mount comprises a "ball and socket" type bearing, which provides for the greatest range of adjusting movement of the shield relative to the support member.

Preferably the engagement means is adjustable, the adjustment being operable to vary the pressure of the retaining members on the bearing member, thereby altering the degree of frictional engagement between the retaining members and the bearing member.

Conveniently the engagement means comprises one or more adjustable screws which, when the mount is assembled, extend from a screw-thread hole in one retaining member to a similar hole provided in the other retaining member, such that adjustment of the one or more screws may vary the degree of frictional engagement between the bearing member and the retaining members. Thus, for example, a tightening adjustment of the one or more screws will tend to bring the retaining members closer together and, in so doing, will tend to increase the degree of frictional engagement between the surface of the retaining members and the surface of the bearing member. Conversely, a loosening adjustment of the one or more screws will decrease the degree of frictional engagement.

In a preferred embodiment, the assembly comprises an inner and an outer retaining member, which retaining members are conveniently generally annular in shape. Desirably the inner and outer retaining members are provided with holes disposed in a circle around the annulus of each retaining member, which holes are equipped with a screw thread.

Corresponding holes in the inner and outer retaining members can be aligned to allow the insertion of an engaging screw therethrough during assembly of the mount.

Typically, when the mount is assembled the inner and outer retaining members present opposed surfaces which are at least partially shaped concavely about the same radius, so as to define a substantially spherical bearing socket, to accommodate a substantially spherical bearing member.

Preferably the inner retaining member has a recessed surface which wholly or partially accommodates the outer retaining member, allowing for a compact assembly. Typically the components of the assembly comprise stainless steel.

In a particular embodiment, the outer retaining member comprises two components: a ring bearing, adjacent to the bearing member: and a retaining ring. Both components are generally annular. The retaining ring comprises stainless steel, whereas the ring bearing comprises a synthetic plastics material, such as Nylon 66.

The assembly is preferably capable of detachable attachment to the radiation shield, conveniently by means of one or more screws. Preferably the exposed edges of the mount are chamfered, so as not to present a dangerously sharp edge. Additionally, the holes into which screws are inserted are preferably countersunk to present a flush surface when the mount is assembled.

The mount may be directly attached to the shield by screws passing through holes drilled in the shield, or the attachment may be by means of an adhesive. The shield may comprise an aperture or recess to accommodate wholly or partially the mount. In one embodiment, the shield comprises a circular aperture which accommodates one of the retaining members.

The mount may further comprise a clamping member, serving to clamp the assembly to the radiation shield. The clamping member is conveniently attached to the assembly by clamping screws, which firmly hold the radiation shield in frictional engagement between the assembly and the clamping member.

It is desirable that the mount is attached at the centre of mass of the shield. This facilitates movement of the shield.

In a second aspect the invention provides a radiation shield in combination with the mount defmed above.

It is an advantage of the present invention that the mount comprises comparatively few components and may be supplied to the purchaser in a partially assembled state and yet may still be supplied as a "flat-pack" package. This is very significant as the shields and supporting arms are rather bulky and expensive to transport. Moreover, the assembly can be provided with the correct degree of frictional engagement (between the bearing member and the retaining members) already selected by the manufacturer.

Also, the invention allows for greater ease of replacement of different shields (or other items of medical equipment) on the supporting arm.

The invention will now be further described by way of illustrative example and with reference to the drawings, of which: Figure 1 is a plan view of a radiation shield mount in accordance with the invention (radiation shield omitted); Figure 2 is a sectional view of the same embodiment, along the line A-A shown in Figure 1; Figure 3 is a plan view of the same embodiment, seen from the opposite direction from that of Figure 1; Figures 4 and 6 are plan views (seen from opposite directions) of the inner retaining member of the mount shown in the preceding Figures, and Figure 5 is a sectional view thereof along the line A-A shown in Figure 4; Figure 7 is a plan view of part of the outer retaining member of the mount shown in Figures 1-3, and Figure 8 is a sectional view thereof along the line A-A shown in Figure 7;; Figures 9 and 11 are plan views (seen from opposite directions) of part of the outer retaining member of the mount shown in Figures 1-3, and Figure 10 is a sectional view thereof along the line A-A shown in Figure 9; Figure 12 shows a side elevation of one end of the support arm to which the mount shown in Figures 1-3 is attached; Figure 13 is a sectional view of the opposite end of the support arm to that shown in Figure 12; and Figure 14 is a sectional view of a slight variant of the embodiment shown in Figure 2.

Detailed Description of an Embodiment In one embodiment (shown in Figures 1-3), the invention provides a "ball and socket" type mount for a radiation shield.

Figure 2 shows a section through the embodiment, along the line A-A shown in Figure 1.

In Figure 2, a lead acrylic radiation shield 2, of standard dimensions (60cm by 80cm by 1.2cm), having the equivalent shielding effect of a 0.5mm thickness of lead, has a substantially circular aperture 4 of 45mm diameter at the centre of mass of the shield 2.

The aperture 4 partially accommodates an assembly 6.

The assembly 6 comprises two retaining members: an inner retaining member 8 and an outer retaining member 10. The outer retaining member 10 comprises two subcomponents: a ring bearing 12 and a retaining ring 14. The inner retaining member 8 and the outer retaining member 10 are retained in operative positions (in which they define a bearing socket) by engagement means, which engagement means comprises four screws 16. The bearing socket defined by the inner and outer retaining members 8, 10 accommodates a spherical bearing member 18, which is welded to one end of a support arm 20. There is also a small gap 48, 2mm wide, provided between adjacent surfaces of the inner and outer retaining members 8, 10, which can be adjusted to allow for wear of the surfaces of the bearing member 18 and the retaining members 8, 10.

Describing the components of the assembly 6 in more detail: the inner retaining member 8 is generally annular and made of stainless steel. Referring to Figures 4-6, the inner retaining member 8 comprises a generally circular opening 22 therethrough, part of the surface 24 surrounding the opening 22 being shaped concavely about a radius (arrowed line B in Figure 5) so as to present a surface capable of allowing smooth rotational movement of the spherical bearing member 18, in any plane, relative to the inner retaining member 8. Eight holes substantially 5mm in diameter, are positioned equidistantly around the inner retaining member 8 on a 36mm pitch circle diameter ("P.C.D.") Four of these holes 26 are countersunk at one end with a 45" chamfer. The other four holes 28 are counterbored (to a width of 6mm) at the same end.The holes 26 and 28 are positioned alternately around the inner retaining member 8. The inner retaining member 8 is counterbored to a width of 50mm to provide a recessed outer surface, which recess accommodates the outer retaining member 10.

As stated previously, the outer retaining member 10 comprises the ring bearing 12 and the retaining ring 14. The ring bearing is generally annular and made of the synthetic material Nylon "66". Referring to Figures 7 and 8, the ring bearing 12 is 6mm thick and has an outer diameter of 48mm, with a generally circular opening 30 therethrough, the surface 32 of the ring bearing 12 surrounding the circular opening 30, being shaped concavely about a radius (arrowed line C in Figure 8) of the same dimension as that about which the surface of the inner retaining member 8 is curved, such that when assembled the inner and outer retaining members 8, 10 define a substantially spherical accommodating socket, allowing smooth rotational movement of the spherical bearing member 18, in any plane, within the asembly 6.The ring bearing 12 comprises four holes 34, which are equidistantly positioned on a 36mm P.C.D. Each hole 34 is circular in cross-section and has a diameter of 5mm. When the mount is assembled, the holes 34 in the ring bearing 12 are aligned with the holes 28 in the inner retaining member 8.

The retaining ring 14 is shown in Figures 9-11. Referring to those figures, the retaining ring 14 is a generally annular component, with a diameter of 50mm and a thickness of 5mm, made of stainless steel. A circular opening 34 passes through the retaining ring 14.

The sides of the retaining ring 14 surrounding the circular opening 34 are parallel at one surface (where the diameter of the opening 34 is 21mm) but diverge outwards at 45" at the opposite surface (where the diameter of the opening 34 increases to 24mm). This is so that the retaining ring 14 does not unduly restrict the relative movement of the support arm 20. The retaining ring 14 comprises four holes 36, equidistantly positioned on a 36mm P.C.D. which, when the mount is assembled, align with the holes 34 in the ring bearing 12 and with the holes 28 in the inner retaining member 8 allowing the insertion of one engaging screw 16 into each of the four holes. The holes 36 are countersunk as shown in Figures 10 and 11, so that the engaging screw 16 does not protrude from the assembly.

The assembly 6 also comprises spherical bearing member 18. This is made of stainless steel and of appropriate diameter to articulate smoothly within the socket formed by the inner and outer retaining members 8, 10 respectively. The spherical bearing member 18 is welded to one end of the support arm 20. The proximal end region of the support arm 20, showing the attached spherical bearing member, is illustrated in Figure 12. Figure 13 shows the distal end region of the support arm 20 together with details of its attachment to an arm pivot 38 via a coupling 40. The coupling 40 is fixed to the arm pivot 38 by means of a LoctiteTM retainer 638 and two screws B. The support arm 20 is detachably secured to the coupling 40 by two screws A.

The assembly 6 is attached to the radiation shield 2 by clamping member 42, shown in Figures 1 and 2. The clamping member 42 is a stainless steel boss with a diameter of 60mm. The clamping member 42 is provided with four holes 44 drilled therethrough, equidistantly positioned on a 36mm P.C.D. which, when the mount is assembled, align with the holes 26 in the inner retaining member 8, thereby allowing insertion of an attachment screw 46 into each of the holes 44/26.

The edges of the clamping member 42, and of the inner retaining member 8, are chamfered, so as not to present a sharp edge, for safety.

A slight modification of the above embodiment is shown in Figure 14. The mount shown in Figure 14 is essentially similar to that in Figure 2, but the profile of the inner retaining member 8 is rather more straightforward, and thus easier to produce.

Claims (10)

Claims

1. A mount for a radiation shield, comprising an assembly capable of attachment to the radiation shield, the assembly comprising a bearing member retained in an accommodating bearing socket formed between two retaining members, and engagement means which retain the retaining members in operative positions in which the retaining members define the bearing socket, the bearing member being movable in the socket to provide for adjusting movement of the shield.

2. A mount according to claim 1, wherein the bearing member is substantially spherical.

3. A mount according to claim 1 or 2, wherein the engagement means is adjustable, the adjustment being operable to vary the degree of frictional engagement between the retaining members and the bearing member.

4. A mount according to any one of claims 1, 2 or 3, wherein the assembly is capable of detachable attachment to the radiation shield.

5. A mount according to any one of the preceding claims, further comprising a clamping member to clamp the assembly to the radiation shield.

6. A mount according to claim 5, wherein the clamping member is attachable to the assembly by clamping screws, which screws serve to hold the radiation shield in frictional engagement between the assembly and the clamping member.

7. A mount according to any one of the preceding claims, wherein one retaining member has a recessed surface which wholly or partially accommodates the other retaining member.

8. A mount according to any one of the preceding claims, comprising a support arm, one end of which is formed with, or attached to, the bearing member.

9. A radiation shield in combination with a radiation shield mount in accordance with any one of the preceding claims.

10. A mount for a radiation shield, substantially as hereinbefore described and with reference to the accompanying drawings.