HU202113B - Process for producing plastic compositions equivalent of tissue body - Google Patents

Abstract

Crosslinked epoxy and aucine polymers are prepd. to contain H, N, C and = elements in equivalent percetange order of magnitude to those. found in human soft tissues.

Description

BACKGROUND OF THE INVENTION The present invention relates to the production of an equivalent polymeric composition of body tissue having a composition and density very close to the soft tissue of the human body. Therefore, it behaves in a manner equivalent to soft tissue against ionizing radiation.

In the field of research, radiation protection practice, radiotherapy and diganostasis, the human body is called tissue equivalent. phantoms. Major components of soft tissue: OC Η. N. The interaction of ionizing radiation with the tissue replicator used depends on its elemental composition and density. The degree of equivalence is thus a function of the elemental composition and density of the tissue replacement material. The better it is, the more accurately it represents the elemental composition and density of the tissue. Very few literature references exist for the production of such materials. In practice, certain radiation qualities and radiation energy replace tissues with materials that do not contain, or only partially contain, elements of the Radiation Protectlon Dosimetry Vol.12 No2 pp. 125128 (1985). but the end result of the interaction is equivalent in some narrow range of energy and qualities to the tissue you want to simulate. Thus, the use is limited to a very narrow range. In some of the tissue-mimicking substances, some artificial macromolecular material - a thermoplastic polymer - is called a so-called "synthetic" material. matrix, and in this matrix the required additives are distributed. Such a matrix material is e.g. polyethylene, polyformaldebid, polystyrene. (1, ref. Cit.). As processing additive, paraffin wax is dispersed in the system, e.g. the so-called MIX-D, a mixture of polyethylene, paraffin wax and inorganic salts (MgO, TiO ₂ ).

Body tissue equivalent compositions. literary reference.

Material Density Η N (% by weight) (% by weight)

Internationally accepted standard composition ” 1 10.1 2.6 Polystyrene 1,029 7.74 - Polyacetal 1,425 6.71 -

A fundamental difficulty with the above thermoplastic polymer-based compositions is the fact that the polymer matrix already has an elemental composition that cannot be modified with additives to the extent necessary. Another difficulty is the inhomogeneity during production, namely air bubbles, shrinkage cracks and inclusions. The primary source of inhomogeneity is the high melt viscosity and high shrinkage of the starting materials after cooling.

Another class of tissue equivalent materials are non-polymer based, gel-containing compositions containing a large amount of water (I-1). However, in these cases, vulnerability, cumbersome handling, and changes in properties over time, represent serious limitations to their usability.

The elimination of the above disadvantages and the need for a relatively simple formulation of a tissue equivalent material that best meets the particular application requirements has led to the discovery of the present invention that optimal tissue equivalent materials can be created using epoxy resin based compositions.

According to our method, a di-bis (glycidyl ether) -based epoxy resin, an aliphatic amine-type crosslinker, and an aliphatic monoepoxy compound used in an unusually high percentage by a person skilled in the art are homogenized.

Once the required crosslink density has been obtained, a transparent composition of sufficient strength is obtained which does not contain any apparent inhomogeneity.

Transparency is advantageous for use. This transparency was not available for previously known tissue analog compositions. (See reference for reference.)

The mechanical strength values of the above composition after crosslinking are characterized by the fact that they can be machined in the plastics industry without further processing.

In the tissue analog compositions prepared by our method, the percentages by weight of hydrogen, nitrogen, carbon + oxygen were equal to the elemental composition of the soft tissue.

In addition, the density of the tissue equivalent produced is equal to that of human soft tissue.

A further significance of the invention is that the manufacture of the material does not require any major investment in machinery (presses, extruders, injection molding machines).

The preparation of the composition according to the invention is described in detail by the following example:

Example 1

At room temperature, in a vessel having a high specific surface area (cm-thick layer thickness), 100 parts by weight of dihydroxydiphenylpropane bis (glycidyl ether) / epoxy equivalent to 190 and a viscosity at 25 'C of 15.6 Pa / 40 parts by weight of normal butyl glyceride. After apparently homogeneous mixing, 4 parts by weight of urea in powder form were added to the mixture, which was then dispersed to molecular size with stirring. Then, 60 parts by weight of polyethylene powder (150,000 by weight, 15 microns average particle size) are added to the mixture and mixed evenly. / cm @ 3 of the above mixture.

After homogeneous mixing, the mixture is vacuum evacuated at 25807-32260 Pa for 15 minutes to remove the mixed air. The thus vented mixture is allowed to cure by pouring it into the preformed mold cavity.

The solid composition obtained after curing had an elemental hydrogen content of 9.9% by weight and an elemental nitrogen content of 3.27% by weight and a density of 1.00 p / cm ³ .

Claims (1)

A process for producing an equivalent plastic composition of body tissue having an elemental hydrogen and nitrogen content of 5% by weight relative to the internationally accepted average human soft tissue and having a density equal to that of human soft tissue, 40 parts by weight of a butyl glycidyl ether reactive diluent, 14 parts by weight of a triethylene-tetramine type crosslinker, 60 parts by weight of polyethylene and 4 parts by weight of urea additive are worked up at room temperature and the resulting composition is left under vacuum for 15 minutes and .