Patent Number: 039420230
Section: description

The mortar-based protective screen for radiological purposes is shown in FIG. 1 as comprising a jacket 1 made of plastics material of the polyamide or elastomer type, or of any other suitable material which is leakproof and inert towards the human body, and is intended to be placed, directly or indirectly, on the patient's skin. Thus it is also possible to use a plasticised fabric to produce the jacket. This jacket 1 comprises two walls 1a and 1b which extend parallel to one another and have a surface area which is very large relative to that of the side wall 1c joining those two parallel walls 1a and 1b. As shown in FIG. 1, the cross-section of the jacket comprising walls 1a and 1b and the side wall 1c is, for example, of rectangular shape. This jacket 1 is filled with (a) a thermosetting resin, for example of the epoxy, polyester or phenolic type, and with (b) a fine particulate filler of at least one substance which absorbs medical radiation. This fine particulate filler is evenly mixed with the said resin and consists of barium sulphate, antimony oxide, silica or lead oxide, or preferably a mixture of at least two of these components. The diameter of the fine particles forming the filler is of the order of a few microns to a few hundred microns. The mixture of thermosetting resin and filler is referenced 2 in FIGS. 1 to 4. A window 3, permeable to medical radiation, is provided preferably in the centre of the jacket and extends between the two parallel walls 1a and 1b of the jacket 1. It is advantageous to produce this window 3 by means of an elongate solid portion which is made of a material such as polyethylene which is permeable to medical radiation, and the window comprises two parallel end faces one of which is preferably firmly fixed, for example by welding or gluing, to one of the parallel walls 1a and 1b of the jacket 1. The height of this elongate portion 3 is substantially the same as the width of the side wall 1c. Furthermore, it is possible to use the height of this elongate portion 3 as a guide in order to determine the appropriate width of the side wall 1c. At its side, the jacket 1 carries a tubular portion 1d, which, on one side, communicates with the inside of the jacket, and which, at its free end, is generally sealed. When the sealed end of the portion has been cut, it is possible to use this portion to introduce the necessary amount of curing agent inside the jacket. Of course, while the contents of the jacket are being mixed, the resulting aperture must be closed, for example by means of a surgical clamp which presses against the two folded-over branches of the tubular portion. It is also possible to place the curing agent too, beforehand, inside the jacket 1. In this case, in order to avoid premature reaction, the curing agent can be contained within a pouch or sachet which can be opened by rupturing and is located inside the jacket. This rupturable pouch or sachet has been indicated diagrammatically at 5 in FIGS. 1 to 4. In a first embodiment, the curing agent 6 is contained in an elongate sachet 5, placed either directly inside the jacket or inside the tubular extension 1d of this jacket 1. The rupturable sachet 5 is partially fixed to the inside face of the jacket 1 or of the tubular extension. When the sachet 5 is placed in the tubular extension 1d, the join between the sachet and the tubular extension is made in the sealing zone of this tubular extension and this sealing can, for example, be effected by welding or gluing. In the embodiment represented in FIGS. 1 and 2, the rupturable sachet consists partially of a rupturable sheet 5a covering the curing agent 6, and partially of a part of the jacket 1 to which the edge of the rupturable sheet 5a is welded. The jacket of the protective screen may, for example, measure 30 cm. by 30 cm. in plan view, and may have a height of the order of a few centimetres, for example 3 cm. A constituent of the composition 2 may be polyepoxides which are organic compounds containing more than one ##EQU1## group. Such polyepoxides can be saturated or unsaturated; aliphatic, cycloaliphatic, aromatic or heterocyclic; can be substituted, if so desired, by substituents such as chlorine atoms, hydroxyl groups, ether radicals and the like; and can also be monomeric or polymeric. In addition to the polyepoxides described above, diluents or elasticising agents, containing at least 10 and preferably at least 12 carbon atoms, may be added to the compositions. Examples of these agents include, amongst others, pine oil, pine oil distillates, tar, bitumens, polythiopolymercaptans, polyamides, aromatic chlorinated compounds, polyesters, monomeric phthalate esters, long chain acids and long chain compounds containing epoxy groups, and their mixtures. The composition 2 hardens under the action of a curing agent. In some cases, the elasticising agent may contain active hydrogen and can also serve as a curing agent. In other cases, it may be necessary to add an elasticising agent to the curing agent. Suitable curing agents containing epoxy groups may be acidic, neutral or alkaline. Examples of these agents are, amongst others, alkalis, carboxylic acids or anhydrides, Friedel-Crafts halogenated compounds, amino compounds, for example ethylene-diamine, addition products of amines and epoxides, and amide derivatives. The proportions, relative to the binder, vary greatly as a function of the curing agent used; for example, quantities from a few % to 300 or 400% by weight can be employed. The unsaturated polyesters to be added to the composition 2 are organic compounds prepared in a manner which is in itself known from unsaturated .alpha.,.beta.-dicarboxylic acids or their anhydrides, or optionally from saturated dicarboxylic acids, and from polyols, or mixed with a solution of an unsaturated polyester in vinyl and/or allyl monomers. It is also known that it is possible to prepare polyesters from polyols and from acids or their esterifiable derivatives by using, as the acid components, benzene-1-amino or 1-alkylamino-3,5-dicarboxylic acids or their lower alkyl esters. Either of the two reactions takes place equally well, for example, in the presence of 10 to 25% by weight of styrene. The copolymerisation of unsaturated esters with vinyl compounds and mainly styrene is carried out in the presence of catalysts which form free radicals. Peroxides, for example benzoyl peroxide, lauryl peroxide, cumene hydroperoxide and the like, and certain aldehyde, ketone, diketone or amine compounds are generally used as catalysts which form free radicals. It is also possible to use polymerisation initiators based on metal salts or amines. These catalysts are used in amounts of the order of 0.01 to 5% by weight. The proportion of radiologically inert particles present in the composition 2 must be at least 25% by weight of the total mixture of the binder and elasticising agents, and preferably between 50 and 1,000% by weight or, even better, between 100 and 400% by weight of the said total mixture. In a first embodiment the jacket contains, as constituents for the synthetic mortar, the following components: polyester resin of type No. 8,000 100 g. polyester resin of type No. 8,130 20 g. precipitated barium sulphate 100 g. antimony oxide as a fine powder 20 g. silica as a fine powder 10 g. curing agent, methyl ethyl ketone peroxide 2 g. In a second embodiment the jacket contains, as constituents for the synthetic mortar, the following components: epoxy resin 100 g. diglycidyl-ethyl 10 g. pine oil 10 g. curing agent, diethylene-triamine 9 g. precipitated barium sulphate 100 g. lead oxide 20 g. silica as a fine powder 10 g. It is advantageous not to use jackets which are thicker than 6 cm. and, in the case where the protective screen must have a greater thickness, it is preferable to superpose several jackets each having a height of less than 6 cm. Where the synthetic mortar composition hardens exothermically, and thus produces a temperature gradient which is too high for the skin of the patient to tolerate, a flexible and heat insulating mass, for example a sheet 7 of foam rubber may advantageously be provided on the wall 1b of the jacket facing the patient. This sheet 7 can be positioned outside or inside the wall of the jacket 1. If it is positioned inside the jacket 1, at least its edge must then adhere, in a leak-proof manner, to the wall 1b. On the other hand, if the sheet 7 is provided on the outer face of the jacket 1, it can then be fixed to the wall 1b by only a few welding or gluing points, and this further improves the heat insulation. It should be understood that the above description is given by way of example only and the scope of the invention should not be considered as being restricted to the specific details given. Modifications can readily be incorporated without departing from the scope of the invention as defined in the following claims.