EP1549220A1

EP1549220A1 - Radiation protection material based on silicone

Info

Publication number: EP1549220A1
Application number: EP04764806A
Authority: EP
Inventors: Barbara Ballsieper
Original assignee: Mavig GmbH
Current assignee: Mavig GmbH
Priority date: 2003-09-03
Filing date: 2004-09-03
Publication date: 2005-07-06
Anticipated expiration: 2024-09-03
Also published as: US20060217477A1; US7432519B2; JP2007504467A; EP1549220B1; WO2005023115A1

Abstract

The invention relates to a lead substitute for radiation protection purposes, said lead substitute containing between 12 and 22 wt. % of matrix material based on silicone, between 1 and 75 wt. % of Sn or Sn compounds, between 0 and 73 wt. % of W or W compounds, and between 0 and 80 wt. % of Bi or Bi compounds, for nominal total lead equivalents of between 0.25 and 2.0 mm. The invention also relates to a lead substitute which additionally contains at least one of the elements Er, Ho, Dy, Tb, Gd, Eu, Sm, Ta, Hf, Lu, Yb, Tm, Th, U and/or the compounds thereof and/or CsI.

Description

Radiation protection material based on silicone

The invention relates to a light lead replacement material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 60-140 kV.

Conventional radiation protection clothing for use in X-ray diagnostics usually contains lead or lead oxide as a protective material.

A substitution of this protective material against other materials is particularly desirable for the following reasons:

On the one hand, lead and its processing lead to a high environmental impact due to its toxicity, on the other hand, lead due to its very high weight necessarily leads to a very high weight of the protective clothing and thus to a high physical strain on the user. When wearing protective clothing, for example in medical operations, the weight is of great importance for the comfort and the physical strain on the doctor and the assistant staff.

For this reason, a replacement material for lead in radiation protection has been sought for years. The use of chemical elements or their compounds with an atomic number of 50 to 76 is mainly proposed.

DE 199 55 192 AI describes a method for producing a radiation protection material from a polymer as a matrix material and the powder of a high atomic number metal.

DE 201 00 267 Ul describes a highly elastic, light, flexible, rubber-like radiation protection material, with additions of chemical elements and their oxides an atomic number greater than or equal to 50 can be added to a special polymer.

In order to reduce weight compared to conventional lead aprons, EP 0 371 699 A1 proposes a material which, in addition to a polymer as a matrix, also has elements of higher atomic numbers. A large number of metals are mentioned.

DE 102 34 159 AI describes a lead replacement material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 60-125 kV.

Another essential component of lead replacement materials is the matrix material, which should have at least two functions. Matrix material means the backing layer for the protective materials, which are made, for example, of rubber, latex, flexible or solid

Polymers can exist. On the one hand, it is desirable for the end product to be as light, elastic and flexible as possible without it being subsequently processed

Cracks or breaks come. On the other hand, it should be ensured that the metallic fillers are distributed absolutely homogeneously, provided that they are firmly integrated into the matrix material, so that a satisfactory abrasion-resistant surface is ensured.

Another point is the environmental compatibility of the matrix materials. Many conventional materials lie as halogen-containing polymers, e.g. B. PVC, before. The use of these materials inevitably leads to serious problems in the manufacture, use and recycling of lead replacement materials, not only for the environment but also for those who come into direct contact with the lead replacement materials.

Furthermore, it has been found that the conventional absorption materials are sometimes considerable tend to emit fluorescent radiation, which is a not negligible health impairment for the contact persons.

Depending on the elements used, the degree of weakening or the lead equivalent (International Standard IEC 61331-1, Protective devices against diagnostic medical X-radiation) of the respective material shows a sometimes very pronounced dependence on the radiation energy, which is a function of the voltage of the X-ray tube.

Compared to lead, lead-free materials have a partly very different absorption behavior depending on the X-ray energy. Therefore, an advantageous combination of different elements is required to simulate the absorption behavior of lead while maximizing weight saving.

For example, the known radiation protection clothing made of lead-free material has a more or less strong decrease in absorption compared to lead below 70 kV and above 110 kV, in particular above 125 kV. This means that in order to achieve the same shielding effect as with lead-containing material, a higher basis weight of the protective clothing is required for this area of the tube tension.

For this reason, the area of application of commercially available lead-free radiation protective clothing is generally restricted.

A radiation protection material is known from US 2002/0179860, which comprises a rubber and a metal, such as tungsten and / or bismuth. Silicone rubber is mentioned as the rubber to be used. The radiation protection materials offer protection in an energy range from 1173 kV to 1 332 kV.

In order to be able to substitute lead for radiation protection purposes, one is as similar as possible with regard to lead Absorption behavior over a larger energy range is required because radiation protection substances are usually classified according to the lead equivalent and the radiation protection calculations are often based on lead equivalents.

Total lead equivalent in a protective layer-like structure of a lead substitute material means the lead equivalent of the sum of all protective layers. Total nominal lead equivalent means the lead equivalent to be specified by the manufacturer for personal protective equipment in accordance with DIN EN 61331-3.

In certain X-ray applications, such as computer tomography and bone density measurements, but also in luggage inspection devices, X-ray voltages of up to 140 kV occur.

The object of the present invention is to provide a lead substitute material which can be used over a wide energy range of an X-ray tube, that is to say over a large energy range, and at the same time contains a matrix material which is environmentally compatible and free from pollutants, against UV radiation is stable.

The object of the invention is achieved by a lead substitute material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 60-140 kV, the lead substitute material 12-22% by weight of a silicone-based material as the matrix material, 1-75% by weight. % Tin or tin compounds, 0-73% by weight tungsten or tungsten compounds, 0-80% by weight bismuth or bismuth compounds. The mixture records nominal total lead equivalents of 0.25-2.0 mm.

The solution to the problem was to find a material selection with regard to the matrix material and the lead substitute metals and their quantity selection, which the X-rays can also be shielded effectively in the high energy range, while at the same time the choice of the silicone-based material provides a lead substitute material which, while maintaining high elasticity, can meet the environmental requirements described above.

It has surprisingly been found that the absorption effect at high energies is significantly improved by high proportions of tungsten and / or bismuth in the lead substitute material.

In a preferred embodiment of the invention, the lead replacement material is characterized in that it contains 12-22% by weight of silicone-based matrix material, 1-39% by weight of Sn or Sn compounds, 0-60% by weight of W or W -Compounds and 0-60 wt .-% Bi or Bi compounds includes.

In a particularly preferred embodiment of the invention, the lead replacement material is characterized in that it contains 12-22% by weight of silicone-based matrix material, 1-39% by weight of Sn or Sn compounds, 16-60% by weight of W or W compounds and 16-60 wt .-% Bi or Bi compounds.

In a further preferred embodiment of the invention, the lead replacement material is characterized in that it contains 12-22% by weight of matrix material based on silicone, 40-60% by weight of Sn or Sn compounds, 7-15% by weight of W or W compounds and 7-15 wt .-% Bi or Bi compounds.

It has been found that any silicone-based material is suitable as the matrix material, provided that it ensures a completely homogeneous, fine, uniform distribution of the metals or their compound. Preferred silicone rubbers are those which have alkyl groups, vinyl groups and / or phenyl groups on the polymer chain. Has been particularly suitable silicone rubber proved. Examples include dimethyl silicone rubber, phenylmethyl rubber, phenyl silicone rubber and polyvinyl rubber.

In a further particularly preferred embodiment of the invention, the lead substitute material is characterized in that it additionally contains up to 40% by weight of one or more of the following elements Er, Ho, Dy, Tb, Gd, Eu, Sm and / or their compounds and / or Csl includes.

The following table 1 shows the mass attenuation coefficients of lead-free protective materials outside the absorption edges at various photon energies. The elements to be used advantageously for the respective energy are underlined.

Table 1

A particularly strong increase in the absorption effect is achieved by the lead substitute material, which additionally comprises one or more of the elements Er, Ho, Dy, Tb, Gd, Eu, Sm and / or their compounds and / or Csl. In this way, the weight of the protective clothing can be significantly reduced.

To achieve the properties described, the individual elements can be compiled in accordance with Table 1 in such a way that a certain energy range is covered or that the weakening is as uniform as possible over a larger energy range.

Surprisingly, it was found that when the above-mentioned additional elements of their compounds are used, a disproportionate increase in the protective effect occurs in the lead substitute material, preferably if their proportion by weight in the lead substitute material is between 20% and 40%.

In a further preferred embodiment of the invention, the lead substitute material is characterized in that it additionally comprises up to 40% by weight of one or more of the following elements Ta, Hf, Lu, Yb, Tm, Th, U and / or their compounds.

In the case of the metals Er, Ho, Dy, Tb, Gd, Eu, Sm, Ta, Hf, Lu, Yb, Tm, Th, U which can also be used in the lead replacement material, metals and / or their compounds and / or Csl can also be used with a relatively low degree of purity are used, as they arise as waste products.

The lead replacement material according to the invention surprisingly fulfills the conditions of a highly shielding radiation protection material, which is elastic and light, and to a high degree meets all requirements for environmental compatibility, eg by the combination of the silicone-based matrix material and the selection of the lead replacement metals or their compounds. B. biocompatibility, recyclability, low emissions.

The lead substitute material according to the invention may also contain fillers for reinforcement and additives in conventional amounts. The fillers include, for example, fibers or fibrous materials made from cotton fibers, synthetic fibers, fiberglass fibers and aramid fibers. Possible reinforcing fillers include highly disperse silica, precipitated silica, iron oxide, titanium oxide, aluminum trihydrate and carbon black.

The lead substitute material according to the invention can also contain processing aids which further improve the properties of the material. These include, for example, typical plasticizers.

DIN EN 61331-3 does not allow a downward deviation from the nominal lead equivalent. Only the German version of the standard allows an exception, namely a deviation of 10% from the nominal lead equivalent. For these reasons, the aim is to aim for the lead equivalent to be as flat as possible over the energy in the case of a lead replacement material.

A drop in the lead equivalent value below the nominal lead equivalent value or below the lower tolerance limit means that the radiation protection material cannot be used at the tube voltages in question, since the shielding effect is too low. In this case, the basis weight of the lead replacement material must alternatively be increased to such an extent that the permissible tolerances of DIN EN 61331-3 are met. However, an increase in the basis weight is considered disadvantageous.

Another possibility is to limit the area of application with regard to the energy or tube voltage.

It was therefore a further aim of the present invention to select elements or their connections in such a way that the lead equivalent in the desired energy use range is reduced as little as possible, taking into account the accessibility of the respective elements or their connections. The relative effectiveness N _rel as an increase in the lead equivalent (PbGW) based on a standardized mass occupancy of 0.1 kg / m ² was determined for a number of materials in test series and summarized in Table 2 below. It reproduces the attenuation properties of the individual elements even more clearly than the mass attenuation coefficients described above, since here the absorption is included in the immediate area of the respective absorption edges.

Table 2

Surprisingly, it was found that the elements or their compounds can be classified as follows:

Group A: Materials with relatively lower effectiveness with values of N _rel <1.2 - 1-6 mm PbGW per 0.1 kg / m ² and a slight or negative increase of 60-80 kV. These elements or their compounds include Sn, Bi and W. Group B: Materials with relatively high effectiveness with N _rel ≥ 1.3 mm PbGW per 0.1 kg / m ² and a high increase of 60-80 kV.

In a particularly preferred embodiment of the invention, the energy range 60-140 kV is therefore divided into several, partly overlapping areas in accordance with the most common uses of X-radiation:

1. Energy range 60-90 kV

In this energy sector, there are predominantly dental applications of single exposure technology and panorama layer technology.

2. Energy range 60-125 kV

The most common X-ray examinations and X-ray interventions, such as angiography, computed tomography, cardiac catheter examinations, interventional radiology, thoracic hard beam technology, are in this energy range.

3. Energy range 100-125 kV

Most computer tomographs fall into this energy range.

4. Energy range 125-150 kV

This is an energy area for special applications, such as special computer tomographs, bone density measurements, special thoracic hard beam technology and nuclear medical diagnostics.

Lead-free protective clothing that can only be used in a certain energy range must be marked accordingly by the manufacturer. In one embodiment of the lead substitute material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 60-90 kV, the lead substitute material for nominal total lead equivalent values of 0.25-0.6 mm is characterized in that it contains 12-22 wt. % of a silicone-based material, 49-65% by weight of Sn or Sn compounds, 0-20% by weight of W or W compounds, 0-20% by weight. Bi or Bi compounds and 5-35 wt .-% of one or more of the elements Gd, Eu, Sm and / or their compounds and / or Csl. The energy range is preferably that of an X-ray tube of a dental X-ray device.

In the relatively narrow energy range, Table 2 showed that Sn is the most effective of Group A elements. From group B, Gd is preferred, but Csl also led to a lead replacement material with very good properties.

Energy range 60-125 kV (general X-ray range):

For example, elements with a small and high increase in the lead equivalent can be selected from Table 2 in such a way that the courses of the lead equivalent remain as flat as possible over the entire range. A certain increase at 80 and 100 kV cannot be avoided physically.

One or more elements or their group A compounds can therefore be optimally combined with one or more elements or their group B compounds, the selection being based on the efficiency of the shielding, on the accessibility of the respective element or its connection, and on the lead equivalent is as constant as possible.

Here, the proportion of the A elements or their compounds is dependent on that of the B elements or given their connections. If the proportion of a B element is increased, the relative weight proportion of an A element with opposite energy behavior must also be increased significantly in order to keep the course of the lead equivalent over the energy as flat as possible.

For example, with a proportion of more than 20% by weight of B elements or their compounds, the proportion of Sn or Bi should rise above 40% by weight in order to ensure a low energy dependence.

Energy range 100-140 kV:

That is the energy range for most newer computer tomographs.

High protective effects or low basis weights can be achieved by using the elements or their connections, which develop their highest shielding effect especially in this small energy range. For reasons of accessibility, a larger proportion of the elements or their compounds of group A should be combined with a smaller proportion of the elements or their compounds of group B, in which case a flat energy course of the lead equivalent is not so important here because of the relatively small energy window is.

Energy range 125-150 kV:

This area concerns special applications in radiology and nuclear medicine. The basis weight of the radiation protection clothing is not the focus of optimization in this area, since the protective clothing is usually only worn here for a short time or stationary radiation protection screens are used.

The elements or their connections are selected according to the criteria mentioned above. Very good results deliver Gd and Er in combination with Bi. The effect of W is too small in this area.

In summary, it can be stated that the composition of protective substances for individual energy areas can be expediently optimized by splitting in accordance with the most frequently occurring X-ray applications.

In a further preferred embodiment of the invention, the lead substitute material has a structure of at least two separate or interconnected protective layers of different compositions, at least in one layer at least 50% of the total weight consisting of only one element from the group Sn, W and Bi or their Connections exist.

In a further preferred embodiment of the invention, the lead substitute material is characterized in that it comprises a structure of at least two separate or interconnected protective layers of different compositions, the protective layer (s) more distant from the body predominantly comprising the elements or their compounds with a higher one X-ray fluorescence yield and the body-near protective layer (s) which comprise elements or their combination with lower X-ray fluorescence yield.

When materials are irradiated with X-rays, characteristic X-rays are excited as fluorescent radiation. The fluorescence yield depends on the atomic number. This proportion of fluorescence leads to additional radiation exposure of the skin and the organs immediately below. It was determined from measurements on protective clothing that, in particular, elements with smaller atomic numbers, in this case Sn in particular, fluoresce particularly strongly. In the case of a layered structure of the radiation protection material, a Layer by element so that the elements with the lowest fluorescence yield lie on the skin side.

The fluorescence component, also referred to as the build-up factor, of commercially available lead-free protective materials (material B) is shown in Table 3 below in comparison to a material (material A) built up in layers according to the principle described here. As can be seen, the build-up factor can reach values of up to 1.42. This means that the skin is 42% more stressed by the fluorescence content in this case.

Table 3

In a further particularly preferred embodiment of the invention, the lead substitute material is characterized in that it has a structure of protective layers of different compositions.

The lead substitute material can comprise a structure of at least two separate or interconnected protective layers of different composition, the protective layer (s) further away from the body predominantly comprising the elements of lower atomic number or their connections and the protective layer (s) close to the body predominantly comprise the elements of higher atomic numbers or their connections.

The lead substitute material can also be characterized in that a weakly radioactive layer is embedded between two separate or radioactive protective layers which are connected to the radioactive layer. It can act as elements or their compounds of group B to shield radiation from high energy, the actinides thorium or uranium, the latter z. B. as depleted uranium. They have a high shielding effect in the energy range 125-150 kV, but are themselves weakly radioactive.

The effect of the natural radiation can be weakened by the fact that the radioactive layer is embedded between two inactive layers made of Bi.

The proportion of self-exposure to thorium or uranium should in most cases be low and therefore negligible. There has to be a balance of advantages here, which is to be compared with the advantages that result from the elimination of lead and from the higher protective effect against the low self-exposure.

In a further preferred embodiment of the invention, the lead substitute material is characterized in that the metals or metal compounds are grained and their grain sizes are a 50th percentile according to the following formula

D ₅₀ = d »p mm 10

where D _{50 is} the 50th percentile of

Grain size distribution, d the layer thickness in mm and p den

Weight fraction of the respective material component on

Mean total weight and the 90th percentile of the grain size distribution is D ≤ 2 • D ₅ .

When measuring the lead equivalent values on protective layers, which consist of metal powders or powders of metal compounds, it surprisingly turned out that the radiolucency of the grained Substances existing layer is higher compared to a film layer with the same mass coverage. This mainly affects the lower energy range of 60-80 kV. At higher energies, the local permeability differences, ie the X-ray contrast, become increasingly smaller.

For example, with a Sn content of 30% = 0.3 and a layer thickness of 0.4 mm

D ₅₀ = 0.4 mm • 0.3 = 0.012mm = 12 μm.

In addition, the 90th percentile of the grain size distribution should not be larger than 2 • D ₅₀ = 24 μm.

Materials with a low proportion by weight must therefore also have a small grain size, i.e. be very finely distributed in order to develop an optimal protective effect.

By using this effect, the weight of radiation protection clothing can be reduced even further.

After the silicone matrix material and the metals / metal compounds have been mixed, the lead substitute material according to the invention is further processed and cured in a manner known per se, after which a homogeneous mixture is obtained, a dense, elastic material being formed into a desired shape. Further processing techniques are, for example, extrusion, injection molding, calendering, compression molding or the injection molding process. In a preferred embodiment, the lead replacement material according to the invention is provided as a sheet product, which is cut into the desired shape according to techniques known per se or the like. becomes.

The material according to the invention can be used, for example, for protective gloves, protective aprons, patient covers, gonadal protection, ovarian protection, dental protection shields, stationary lower body protection, table tops, stationary or portable radiation protection walls or radiation protection curtains can be used advantageously.

In the following, the invention will be explained in more detail by means of examples with reference to the drawing. The drawing shows:

1: the lead replacement material according to the invention with 22% by weight of tin, 27% by weight of tungsten, 4% by weight of erbium and 15% by weight of silicone matrix material,

2: the lead replacement material according to the invention with 20% by weight of tin, 36% by weight of tungsten, 29% by weight of bismuth and 15% by weight of silicone matrix material and

3: the calculated relative weights per unit area of the protective clothing according to the invention with nominal bleaching equivalents of 0.5 mm according to Examples 3, 4 and 6 in comparison to a lead apron with 0.5 mm lead equivalent.

example 1

FIG. 1 shows the lead replacement material according to the invention with 22% by weight of tin, 27% by weight of tungsten, 4% by weight of erbium and 15% by weight of silicone matrix material. This lead replacement material is designated by 2 in FIG. 1 denotes a commercially available material with the composition 65% by weight antimony, 20% by weight tungsten and 15% by weight matrix material.

FIG. 1 shows a weight comparison of lead substitute materials with a nominal lead equivalent of 0.5 mm.

It can be seen from FIG. 1 that the basis weight required to achieve a nominal lead equivalent of 0.5 mm is between 100 and 140 kV in the material according to the invention only increases by about 7%, while the increase in the comparison material is considerably greater.

Example 2

FIG. 2 shows the lead replacement material according to the invention with 20% by weight of tin, 36% by weight of tungsten, 29% by weight of bismuth and 15% by weight of silicone matrix material. This lead replacement material is designated by 2 in FIG. 1 denotes a commercially available material with the composition 70% by weight of tin, 10% by weight of barium and 20% by weight of matrix material.

FIG. 2 shows a weight comparison of lead substitute materials with a nominal lead equivalent of 0.5 mm.

From FIG. 2 it can be seen that the basis weight between 100 and 140 kV required to achieve a nominal lead equivalent of 0.5 mm only increases by approximately 9% in the material according to the invention, while the increase in the comparison material is approximately 60% ,

Example 3

Lead-free, light radiation protection apron for the dental area of 60-90 kV Pb nominal lead equivalent 0.5 mm.

A lead-free radiation protection apron was produced from 59% by weight of Sn, 24% by weight of Gd, 1% by weight of W and 16% by weight of silicone matrix material.

The radiation protection effect corresponded to that of a corresponding lead apron with a basis weight reduced by approximately 35% of only 4.4 kg / m ² .

Example 4 Lead-free lightweight radiation protection apron for the application range 60-125 kV.

A radiation protection apron was produced from 50% by weight of Sn, 11% by weight of W, 23% by weight of Gd and 16% by weight of silicone matrix material.

This resulted in a basis weight of 4.5 kg / m ² for a nominal lead equivalent of 0.5 mm lead, a basis weight of 3.3 kg / m ² for a nominal lead equivalent of 0.35 mm lead and a nominal Lead equivalent of 0.25 mm lead has a basis weight of 2.4 kg / m ² .

Example 5

Lead-free, light radiation protection apron for the application range 60-125 kV.

A radiation protection apron was produced from 40% by weight of Bi, 20% by weight of Sn, 24% by weight of Gd and 16% by weight of silicone matrix material.

This resulted in a basis weight of 5.0 kg / m ² for a nominal lead equivalent of 0.5 mm lead.

Lead-free commercially available radiation protection aprons have nominal weights of 0.50 mm basis weights of 5.4 to 6.1 kg / m ² . Conventional lead rubber material has a basis weight of 6.75 kg / m ² .

This shows the essential advantage of the present invention, according to which the protective clothing can become considerably lighter. This is a very important advantage, especially when the protective clothing is used for several hours.

If the user works with tube voltages of 80-100 kV, the lead equivalent is also approx. 20% above the nominal value of 0.5 mm Pb of a corresponding lead apron. This means additional increased radiation protection.

Example 6

Lead-free, light radiation protection apron for computer tomography.

A radiation protection apron was produced from 40% by weight of Bi, 10% by weight of W, 34% by weight of Gd and 16% by weight of silicone matrix material.

The result was a surprisingly low basis weight for a nominal lead equivalent of 0.5 mm of only 4.6 kg / m ² .

Example 7

Lead-free lightweight apron for nuclear medicine applications.

A nuclear medical apron was produced from 50% by weight of Bi, 25% by weight of Gd, 9% by weight of Er and 16% by weight of silicone matrix material.

The basis weight for 4.8 nominal total lead equivalent was 4.8 kg / m ² .

Example 8

FIG. 3 shows the calculated relative weights per unit area of the protective clothing according to the invention with nominal bleaching equivalents of 0.5 mm according to Examples 3, 4 and 6 in comparison to a lead apron with a lead equivalent of 0.5 mm. From the illustration it can be seen that the protective aprons for dental use, general X-ray and computer tomography (CT) each have the lowest basis weight in the intended energy ranges.

Claims

Expectations

1. lead substitute material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 60-140 kV, the lead substitute material for nominal total lead equivalents of 0.25-2.00 mm 12-22% by weight of a silicone-based material, 1-75% by weight of Sn or Sn compounds, 0-73% by weight of W or W compounds, 0-80% by weight of Bi or Bi compounds.

2. Lead replacement material according to claim 1, characterized in that the lead replacement material 12-22 wt .-% of the silicone-based material, 1-39 wt .-% Sn or Sn compounds, 0-60 wt .-% W or W compounds and 0-60% by weight of Bi or Bi compounds.

3. Lead replacement material according to claim 2, characterized in that the lead replacement material

12-22% by weight of the silicone-based material, 0-39% by weight of Sn or Sn compounds, 16-60% by weight of W or W compounds and

16-60 wt .-% Bi or Bi compounds comprises.

4. Lead replacement material according to claim 1, characterized in that the lead replacement material

12-22% by weight of the silicone-based material, 40-60% by weight of Sn or Sn compounds, 7-15% by weight of W or W compounds and 7-15% by weight of Bi or Bi compounds ,

5. Lead replacement material according to one of claims 1 to 4, characterized in that the lead replacement material additionally up to 40 wt .-% of one or more of the following elements Er, Ho, Dy, Tb, Gd, Eu, Sm and / or their compounds and / or Csl.

6. Lead replacement material according to claim 5, characterized in that the lead replacement material additionally comprises up to 20% by weight of the elements and / or their compounds and / or Csl.

7. Lead replacement material according to claim 6, characterized in that the lead replacement material additionally comprises up to 8% by weight of the elements and / or their compounds and or Csl.

8. Lead replacement material according to one of claims 1 to 7, characterized in that the lead replacement material additionally up to 40 wt .-% of one or more of the following elements Ta, Hf, Lu, Yb, Tm, Th, U and / or of their connections.

9. lead replacement material according to claim 8, characterized in that the lead replacement material additionally comprises up to 20 wt .-% of the elements and / or their compounds.

10. Lead replacement material according to claim 9, characterized in that the lead replacement material additionally comprises up to 8% by weight of the elements and / or their connections.

11. Lead replacement material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 60-90 kV according to one of claims 5 to 10, characterized in that the lead replacement material for nominal total lead equivalents of 0.25-0.6 mm 12- 22% by weight of the silicone-based material, 49-65% by weight of Sn or Sn compounds, 0-20% by weight of W or W compounds, 0-20% by weight of Bi or Bi compounds and 5-35 wt .-% of one or more of the elements Gd, Eu, Sm and / or their compounds and / or Csl comprises.

12. Lead replacement material according to one of claims 1 to 11, characterized in that the silicone-based material comprises silicone rubber.

13. Lead substitute material according to claim 12, characterized in that the silicone rubber comprises methyl methyl silicone rubber, phenyl methyl silicone rubber, phenyl silicone rubber and polyvinyl silicone rubber.

14. Lead replacement materials according to one of claims 1 to 13, characterized in that it comprises fillers and processing aids.

15. Lead replacement material according to one of claims 1 to 14, characterized in that it comprises a structure of protective layers of different compositions.

16. Lead substitute material according to claim 15, characterized in that it comprises a structure of at least two separate or interconnected protective layers of different composition, wherein the more protective layer (s) removed from the body predominantly the elements of lower atomic number or their compounds and the protective layer (s) close to the body predominantly comprise the elements of a higher atomic number or their connections.

17. Lead replacement material according to claim 15 or 16, characterized in that it comprises a structure of at least two separate or interconnected protective layers of different compositions, at least one Layer at least 50% of the total weight consists of only one element from the group Sn, W and Bi or their compounds.

18. Lead substitute material according to claim 16, characterized in that it comprises a structure of at least two separate or interconnected protective layers of different compositions, the protective layer (s) further away from the body predominantly comprising the elements or their connections with higher X-rays. Fluorescence yield and the body-near protective layer (s) which comprise elements or their compounds with lower X-ray fluorescence yield.

19. Lead replacement material according to one of claims 16 to 18, characterized in that a weakly radioactive layer is embedded between two separate or non-radioactive protective layers connected to the radioactive layer.

20. Lead replacement material according to one of claims 1 to 19, characterized in that the metals or metal compounds are grained and their grain sizes a 50th percentile according to the following formula.

D ₅₀ = d «p mm 10

have wherein

D _is the 50th percentile of the grain size distribution, d is the layer thickness in mm and p is the weight fraction of the respective material component of the total weight, and the 90th percentile of the grain size distribution is D ₉₀ ≤ 2 »D ₅₀ .

21. Radiation protective clothing made of lead substitute material according to one of claims 1 to 20.