EP1536732B1 - Light radiation protection material for a large energy application field - Google Patents

Light radiation protection material for a large energy application field Download PDF

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Publication number
EP1536732B1
EP1536732B1 EP04764812A EP04764812A EP1536732B1 EP 1536732 B1 EP1536732 B1 EP 1536732B1 EP 04764812 A EP04764812 A EP 04764812A EP 04764812 A EP04764812 A EP 04764812A EP 1536732 B1 EP1536732 B1 EP 1536732B1
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compounds
substitute material
lead
lead substitute
material according
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German (de)
French (fr)
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EP1536732A1 (en
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Heinrich Eder
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Mavig GmbH
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Mavig GmbH
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Priority claimed from DE102004001328A external-priority patent/DE102004001328A1/en
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F1/00—Shielding characterised by the composition of the materials
    • G21F1/12—Laminated shielding materials
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F3/00—Shielding characterised by its physical form, e.g. granules, or shape of the material
    • G21F3/02—Clothing
    • G21F3/03—Aprons

Definitions

  • the invention relates to a 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 protective material.
  • the DE 199 55 192 A1 describes a method for producing a radiation protection material from a polymer as matrix material and the powder of a metal of high atomic number.
  • the DE 201 00 267 U1 describes a highly elastic, lightweight, flexible, rubbery radiation protection material wherein additions of chemical elements and their oxides having an atomic number greater than or equal to 50 are added to a specific polymer.
  • the DE 102 34 159.1 describes a lead substitute material for radiation protection purposes in the energy range of an x-ray tube with a voltage of 60-125 kV.
  • the FR-A-2741472 describes metal alloys used in the field of radiation protection.
  • the alloys preferably contain lead or, if no lead is included, they do not have tungsten.
  • US-A-5,360,666 materials for protective shields are known for use during radiotherapy.
  • the materials are alloys that consist of two elements, none of which is tungsten.
  • the degree of attenuation or the lead equivalent (International Standard IEC 61331-1, Protective devices against diagnostic medical radiation x-radiation) of the respective material shows a partially very pronounced dependence on the beam energy, which is a function of the voltage of the X-ray tube.
  • Lead-free materials have lead behavior that differs greatly from that of lead, depending on the X-ray energy. Therefore, for simulating the absorption behavior of lead while maximizing weight savings, an advantageous combination of different elements is required.
  • the known radiation protective clothing made of lead-free material compared to lead a more or less severe drop in absorption below 70 kV and above 110 kV, especially about 125 kV. That is, to achieve the same shielding effect as with leaded material, a higher basis weight of protective clothing is required for this range of tube tension.
  • Total lead equivalent in a protective-layer-shaped construction of a lead substitute material is understood to be the lead equivalent of the sum of all protective layers.
  • the total nominal equivalent value is understood to mean the lead equivalent value specified by the manufacturer of personal protective equipment according to DIN EN 61331-3.
  • Matrix material is understood as meaning the carrier layer for the protective materials, which may consist of rubber, latex, flexible or solid polymers, for example.
  • X-ray voltages of up to 140 kV occur in certain X-ray applications, such as computed tomography and bone density measurements, as well as in luggage inspection equipment.
  • the object of the present invention is to replace lead as a radiation protection material in terms of its shielding properties over a wide energy range of an X-ray tube, so over a large energy range and at the same time to achieve the largest possible weight reduction. In this case, only environmentally friendly materials should be used compared to lead.
  • the object of the invention is a lead substitute material for radiation protection purposes in the energy sector an X-ray tube with a voltage of 60-140 kV, wherein the lead substitute material 12-22 wt .-% matrix material, 0-75 wt .-% tin or tin compounds, 0-73 wt .-% tungsten or tungsten compounds, 0- 80 wt .-% bismuth or bismuth compounds and wherein at most one of the components is 0 wt .-%, wherein this component is not tungsten or the tungsten compound.
  • the mixture detects nominal total lead values of 0.25-2.0 mm.
  • the lead substitute material is characterized by having 12-22 wt% matrix material, 0-39 wt% Sn or Sn compounds, 0-60 wt% W or W compounds and 0-60% by weight of Bi or Bi compounds, and wherein at most one of the components is 0% by weight, which component is not tungsten or the tungsten compound.
  • the lead substitute material is characterized in that it contains 12-22% by weight of matrix 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.
  • the lead substitute material is characterized in that it comprises 12-22% by weight matrix material, 40-60% by weight Sn or Sn compounds, 7-15% by weight W or W Compounds and 7-15 wt .-% Bi or Bi compounds.
  • the lead substitute material is characterized in that it additionally contains up to 40% by weight of one or more of Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd , Cs, Ba, I and / or their compounds and / or CsI.
  • Table 1 shows the mass attenuation coefficients of lead-free protective substances outside the absorption edges at different photon energies. The advantageous elements to be used for the respective energy are underlined.
  • the lead substitute material additionally comprising one or more elements Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I and / or their compounds and / or CsI is a reached a particularly strong increase in the absorption effect. In this way, the weight of the protective clothing can be significantly reduced.
  • the individual elements can be assembled so that a certain energy range is covered or that the most uniform course of the weakening results over a larger energy range.
  • 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.
  • a fall in the lead equivalent below the nominal lead equivalent or below the lower tolerance limit means that the radiation protection material can not be used at the relevant tube voltages, since the shielding effect is too low.
  • the basis weight of the lead substitute material must be increased to the extent that the permissible tolerances of DIN EN 61331-3 are met.
  • an increase in basis weight is considered disadvantageous.
  • Pb) PbGW increase from 60 to 80 kV based on 0.1 kg / m 2 group 60-90 kV 60-125 kV 100-125 kV 125-150 kV sn 1.64 1.30 0.96 0.80 -0,005 A Bi 1.41 1.27 1.13 1.17 -0,005 A W 0.91 1.07 1.25 1.07 + -0.000 A Gd 1.85 2.05 2.27 1.56 +0.007 B He 1.20 1.45 1.70 1.36 +0.009 B
  • Group A Relatively low efficiency materials with values of N rei ⁇ 1.2 - 1-6 mm PbGW per 0.1 kg / m 2 and a small or negative increase of 60-80 kV. These elements or their compounds include Sn, Bi and W.
  • Group B Relatively high efficiency materials with N rei ⁇ 1.3 mm PbGW per 0.1 kg / m 2 and a high rise of 60-80 kV.
  • the energy range 60-140 kV is divided into several, partly overlapping, regions corresponding to the most common applications of the x-ray radiation:
  • This area of energy includes the most common X-ray examinations and X-ray interventions, such as angiography, computed tomography, cardiac catheter examinations, interventional radiology, thorax hard-beam technique.
  • Lead-free protective clothing that can only be used in a certain energy range must be marked accordingly by the manufacturer.
  • the lead substitute for nominal total lead equivalent of 0.25-0.6 mm is characterized by having 12-22 wt. % Matrix material, 49-65 wt% Sn or Sn compounds, 0-20 wt% W or W compounds, 0-20 wt% Bi or Bi compounds, and 2-35 wt% of one or more of the elements Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I, Pr and / or their compounds and / or CsI, wherein W or the W compound is not O.
  • the energy range is preferably that of an X-ray tube of a dental X-ray machine.
  • the lead substitute material comprises 2-25% by weight of I, Cs, Ba, La, Ce, Pr and / or Nd and / or their compounds and / or CsI.
  • elements with low and high rise of the lead equivalent in be advantageously selected in such a way that the curves of the lead equivalent remain as flat as possible over the entire range.
  • a certain elevation at 80 and 100 kV is physically impossible to avoid.
  • one or more elements or their compounds of group A can be optimally combined with one or more elements or their compounds of group B, the choice being made according to the efficiency of the shield, the accessibility of the element or its compound and As constant as possible of the lead equivalent takes place.
  • the proportion of Sn or Bi should exceed 40% by weight to ensure low energy dependence.
  • the lead replacement material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 100-140 kV is characterized in that the lead replacement material for nominal total lead equivalent values of 0.2 5-0.6 mm 12- 12. 22 wt .-% matrix material, 40-73 wt .-% Bi and / or W or their compounds (where W is always anscherd), and 5-38 wt .-% of one or more of comprises the following elements Gd, Eu, Er, Hf and / or their compounds.
  • High protective effects or low basis weights can be achieved by using the elements or their compounds, which have their highest shielding effect especially in this small energy range.
  • a greater proportion of the elements or their group A compounds should be combined with a smaller proportion of the elements or their group B compounds, in which case a flat energy balance of the lead equivalent will not be so important because of the relatively small energy window is.
  • This area concerns special applications in radiology and nuclear medicine.
  • the weight per unit area of the radiation protection apron is not in the foreground of the optimization in this area since the protective clothing is generally worn here only for a short time or stationary radiation protection screens are used.
  • composition of protective substances for individual energy ranges can be expediently optimized by splitting according to the most frequently occurring X-ray applications.
  • the lead substitute material has a structure of at least two separate or interconnected protective layers of different composition, wherein 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.
  • the lead substitute material has a structure of at least two separate or interconnected protective layers of different composition, wherein at least one layer at least 50% of the total weight only of at least 40 wt .-% Sn or its compounds and at least 10 wt .-% I. , Cs, Ba, La, Ce, Pr and / or Nd and / or their compounds and / or CsI.
  • a layer comprising 40 to 50 wt .-% Sn and 10 to 20 wt .-% cerium.
  • the lead substitute material is characterized in that it comprises a construction of at least two separate or interconnected protective layers of different composition, wherein the protective layer (s) removed from the body predominantly the elements or their compounds with higher X-ray fluorescence yield and the body-near protective layer (s) comprise the elements or their compounds with lower X-ray fluorescence yield.
  • the fluorescence component also referred to as build-up factor
  • the fluorescence component is represented by commercially available lead-free protective materials (material B) in the following Table 3 in comparison with a material constructed in layers according to the principle described here (material A).
  • the build-up factor can reach values up to 1.42. That is, the skin is burdened in this case by the fluorescent component by 42% more.
  • Table 3 kV Material A Material B 80 1.15 1.42 90 1.14 1.35 100 1.14 1.32 110 1.16 1.36
  • the lead substitute material is characterized in that it has a structure of protective layers of different composition.
  • the lead substitute material may comprise a construction of at least two separate or interconnected protective layers of different composition, with the body-removed protective layer (s) predominantly comprising the lower atomic number elements or their compounds and the proximal protective layer (s) comprise the elements of higher atomic number or their compounds.
  • the lead substitute material may also have a construction of at least three separate or interconnected protective layers of different composition, the more remote from the body protective layer (s) and the near-main (s) protective layer (s) predominantly the elements of higher atomic numbers or their compounds include and in the middle at least one Protection with predominantly elements of low atomic numbers is arranged.
  • a barrier layer of a material of higher atomic numbers such as bismuth or tungsten.
  • a layer or layers of a material with a lower atomic number In between lies a layer or layers of a material with a lower atomic number. The resulting fluorescence radiation is thus effectively shielded on both sides and can not penetrate to the outside.
  • a layer structure of at least one highly concentric, compacting powder layer of a mixture of the abovementioned protective substances and at least two carrier layers can be provided on both sides of the powder layer.
  • the powder layer contains as little matrix material as possible.
  • the carrier layers may be composed of matrix material. Suitable materials include polymers such as latex or elastomers.
  • the carrier layers increase the mechanical stability, while the concentrated filling improves the radiation-shielding effect.
  • FIG. 4 shows this layer structure with a highly compressed protective material layer 2 as the core and the outer carrier layers 1.
  • the lead substitute material may also be characterized in that a weakly radioactive layer is embedded between two separate or nonradioactive protective layers connected to the radioactive layer.
  • the effect of self-radiation can be mitigated by embedding the radioactive layer between two non-active layers of Bi.
  • the proportion of self-exposure by thorium or uranium should be low in most cases and therefore negligible. There is a trade-off here, which contrasts the benefits of lead elimination and higher protection with low intrinsic exposure.
  • the radiation permeability of the layer consisting of granular substances 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 transmission differences, i. the X-ray contrast, increasingly lower.
  • low weight materials must also have a small grain size, i. be very finely distributed to develop an optimal protective effect.
  • the material of the invention can be used advantageously for example in protective gloves, patient covers, gonadal protection, ovarian protection, dental shields, fixed lower body protection, table tops, stationary or portable radiation protection walls or radiation curtains.
  • 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 matrix material.
  • This lead substitute material is designated 2 in FIG. 1. 1. 1 denotes a commercially available material of the composition 65% by weight of antimony, 20% by weight of tungsten and 15% by weight of matrix material.
  • Fig. 1 shows a weight comparison of lead substitutes with a nominal lead equivalent of 0.5 mm.
  • 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 matrix material.
  • This lead substitute material is designated 2 in FIG. 1 denotes a commercially available material of 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 substitutes with a nominal lead equivalent of 0.5 mm.
  • a lead-free radiation protection apron was produced from 59% by weight Sn, 24% by weight Gd, 1% by weight W and 16% by weight matrix material.
  • the radiation protection effect corresponded to that of a corresponding lead apron with a reduced basis weight of only 4.4 kg / m 2 by about 35%.
  • Lead-free lightweight radiation protection apron for the application range 60-125 kV.
  • a radiation protection apron was made from 50% by weight Sn, 11% by weight W, 23% by weight Gd and 16% by weight matrix material.
  • 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 matrix material.
  • FIG. 3 shows the calculated relative basis weights of the protective clothing according to the invention with nominal lead equivalents of 0.5 mm according to Examples 3, 4 and 5 in comparison with a lead apron with 0.5 mm lead equivalent. From the illustration it can be seen that the protective aprons for dental application, general X-ray and computer tomography (CT) each have the lowest basis weight in the envisaged energy ranges.
  • CT computer tomography
  • the lead equivalent value is approximately 20% higher than the nominal value of 0.5 mm Pb of a corresponding bleaching apron. This means an additional increased radiation protection.
  • Lead-free lightweight apron in the energy range from 60 to 120 kV with two-layer construction.
  • the matrix content is 15% by weight.
  • composition of protective material layers was chosen: layer Element / compound Material weight (kg / m 2 ) Fluorescent layer (outside) sn 1.20 Gd (oxide) 0.72 Cerium (oxide) 0.48 Barrier layer (inside) Bi 1.44 W 0.48 Gd (oxide) 0.48

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Laminated Bodies (AREA)
  • Materials For Medical Uses (AREA)
  • Professional, Industrial, Or Sporting Protective Garments (AREA)

Description

Die Erfindung betrifft ein Blei-Ersatzmaterial für Strahlenschutzzwecke im Energiebereich einer Röntgenröhre mit einer Spannung von 60-140 kV.The invention relates to a lead replacement material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 60-140 kV.

Herkömmliche Strahlenschutzkleidung zur Anwendung in der Röntgendiagnostik enthält meist Blei oder Bleioxid als Schutzmaterial.Conventional radiation protection clothing for use in X-ray diagnostics usually contains lead or lead oxide as protective material.

Eine Substitution dieses Schutzmaterials gegen andere Materialien ist insbesondere aus folgenden Gründen wünschenswert:Substitution of this protective material for other materials is desirable, in particular, for the following reasons:

Zum einen führt Blei und seine Verarbeitung aufgrund seiner Toxizität zu einer hohen Umweltbelastung, zum anderen führt Blei aufgrund seines sehr hohen Gewichts notwendigerweise zu einem sehr hohen Gewicht der Schutzkleidung und damit zu einer starken physischen Belastung des Anwenders. Beim Tragen von Schutzkleidung, beispielsweise bei medizinischen Operationen, ist das Gewicht für den Tragekomfort und die physische Belastung des Arztes und des Assistenzpersonals von großer Bedeutung.On the one hand leads lead and its processing due to its toxicity to a high environmental impact, on the other hand leads lead due to its very high weight necessarily to a very high weight of the protective clothing and thus to a strong physical burden on the user. When wearing protective clothing, for example during medical operations, the weight is of great importance for the wearing comfort and the physical stress of the physician and the assistant personnel.

Deshalb wird seit Jahren nach einem Ersatzmaterial für Blei beim Strahlenschutz gesucht. Dabei wird vorwiegend der Einsatz von chemischen Elementen oder deren Verbindungen mit der Ordnungszahl von 50 bis 76 vorgeschlagen.Therefore, for years, a replacement lead material has been sought in radiation protection. Here, the use of chemical elements or their compounds with the atomic number of 50 to 76 is mainly proposed.

Die DE 199 55 192 A1 beschreibt ein Verfahren zur Herstellung eines Strahlungsschutzmaterials aus einem Polymer als Matrixmaterial und dem Pulver eines Metalls hoher Ordnungszahl.The DE 199 55 192 A1 describes a method for producing a radiation protection material from a polymer as matrix material and the powder of a metal of high atomic number.

Die DE 201 00 267 U1 beschreibt ein hochelastisches, leichtes, flexibles, gummiartiges Strahlenschutzmaterial, wobei Zusätze von chemischen Elementen und deren Oxide mit einer Ordnungszahl größer gleich 50 zu einem speziellen Polymer gegeben werden.The DE 201 00 267 U1 describes a highly elastic, lightweight, flexible, rubbery radiation protection material wherein additions of chemical elements and their oxides having an atomic number greater than or equal to 50 are added to a specific polymer.

Zur Gewichtsreduzierung gegenüber herkömmlichen Bleischürzen wird in der EP 0 371 699 A1 ein Material vorgeschlagen, das ebenfalls neben einem Polymer als Matrix Elemente höherer Ordnungszahl aufweist. Dabei wird eine große Anzahl von Metallen genannt.To reduce weight compared to conventional lead aprons is in the EP 0 371 699 A1 proposed a material which also has elements of higher atomic number in addition to a polymer as a matrix. This is called a large number of metals.

Die DE 102 34 159.1 beschreibt ein Blei-Ersatzmaterial für Strahlenschutzzwecke im Energiebereich einer Röntgenröhre mit einer Spannung von 60-125 kV.The DE 102 34 159.1 describes a lead substitute material for radiation protection purposes in the energy range of an x-ray tube with a voltage of 60-125 kV.

Die FR-A-2741472 beschreibt Metalllegierungen, die auf dem Gebiet des Strahlenschutzes eingesetzt werden. Die Legierungen enthalten vorzugsweise Blei, oder, wenn kein Blei enthalten ist, weisen diese kein Wolfram auf.The FR-A-2741472 describes metal alloys used in the field of radiation protection. The alloys preferably contain lead or, if no lead is included, they do not have tungsten.

Aus US-A-5,360,666 sind Materialien für Schutzschilder zur Verwendung während einer Strahlentherapie bekannt. Die Materialien sind Legierungen, die aus zwei Elementen bestehen, wovon keines davon Wolfram ist.Out US-A-5,360,666 For example, materials for protective shields are known for use during radiotherapy. The materials are alloys that consist of two elements, none of which is tungsten.

Je nach eingesetzten Elementen zeigt der Schwächungsgrad bzw. der Bleigleichwert (International Standard IEC 61331-1, Protective devices against diagnostic medical x-radiation) des jeweiligen Materials eine teilweise sehr ausgeprägte Abhängigkeit von der Strahlenenergie, die eine Funktion der Spannung der Röntgenröhre ist.Depending on the elements used, the degree of attenuation or the lead equivalent (International Standard IEC 61331-1, Protective devices against diagnostic medical radiation x-radiation) of the respective material shows a partially very pronounced dependence on the beam energy, which is a function of the voltage of the X-ray tube.

Bleifreie Materialien haben gegenüber Blei ein zum Teil stark abweichendes Absorptionsverhalten in Abhängigkeit von der Röntgenenergie. Deshalb ist für die Nachbildung des Absorptionsverhaltens von Blei bei gleichzeitiger Maximierung der Gewichtseinsparung eine vorteilhafte Kombination unterschiedlicher Elemente erforderlich.Lead-free materials have lead behavior that differs greatly from that of lead, depending on the X-ray energy. Therefore, for simulating the absorption behavior of lead while maximizing weight savings, an advantageous combination of different elements is required.

So besitzen die bekannten Strahlenschutzkleidungen aus bleifreiem Material gegenüber Blei einen mehr oder minder starken Abfall der Absorption unterhalb von 70 kV und über 110 kV, insbesondere über 125 kV. Das heißt, zur Erzielung der gleichen Abschirmwirkung, wie bei bleihaltigem Material ist für diesen Bereich der Röhrenspannung ein höheres Flächengewicht der Schutzkleidung erforderlich.Thus, the known radiation protective clothing made of lead-free material compared to lead a more or less severe drop in absorption below 70 kV and above 110 kV, especially about 125 kV. That is, to achieve the same shielding effect as with leaded material, a higher basis weight of protective clothing is required for this range of tube tension.

Deshalb ist der Anwendungsbereich von handelsüblicher bleifreier Strahlenschutzleidung in der Regel eingeschränkt.Therefore, the scope of commercial lead-free radiation protection clothing is usually limited.

Um Blei für Strahlenschutzzwecke substituieren zu können, ist ein in Bezug auf Blei möglichst gleichartiges Absorptionsverhalten über einen größeren Energiebereich erforderlich, da Strahlenschutzstoffe üblicherweise nach dem Bleigleichwert eingestuft werden und die Strahlenschutzberechnungen häufig auf Bleigleichwerten basieren.In order to substitute lead for radiation protection purposes, an absorption behavior which is as similar as possible to lead is required over a relatively large energy range, since radiation protection agents are usually classified according to the lead equivalent and the radiation protection calculations are often based on lead equivalents.

Unter Gesamtbleigleichwert bei einem schutzschichtenförmigen Aufbau eines Blei-Ersatzmaterials versteht man den Bleigleichwert der Summe aller Schutzschichten. Unter Gesamt-Nennbleigleichwert wird der nach DIN EN 61331-3 vom Hersteller für persönliche Schutzausrüstung anzugebende Bleigleichwert verstanden.Total lead equivalent in a protective-layer-shaped construction of a lead substitute material is understood to be the lead equivalent of the sum of all protective layers. The total nominal equivalent value is understood to mean the lead equivalent value specified by the manufacturer of personal protective equipment according to DIN EN 61331-3.

Unter Matrixmaterial versteht man die Trägerschicht für die Schutzmaterialien, die beispielsweise aus Gummi, Latex, flexiblen oder festen Polymeren bestehen kann.Matrix material is understood as meaning the carrier layer for the protective materials, which may consist of rubber, latex, flexible or solid polymers, for example.

Bei bestimmten Röntgenanwendungen, wie der Computertomographie und bei Knochendichtenmessungen, aber auch bei Gepäckprüfungsgeräten, treten Röntgenspannungen von bis zu 140 kV auf.X-ray voltages of up to 140 kV occur in certain X-ray applications, such as computed tomography and bone density measurements, as well as in luggage inspection equipment.

Die Aufgabe vorliegender Erfindung besteht darin, Blei als Strahlenschutzmaterial hinsichtlich seiner Abschirmeigenschaften über einen weiten Energiebereich einer Röntgenröhre, also über einen großen Energiebereich zu ersetzen und dabei gleichzeitig eine möglichst große Gewichtsreduzierung zu erreichen. Dabei sollen ausschließlich gegenüber Blei umweltfreundliche Materialien zum Einsatz kommen.The object of the present invention is to replace lead as a radiation protection material in terms of its shielding properties over a wide energy range of an X-ray tube, so over a large energy range and at the same time to achieve the largest possible weight reduction. In this case, only environmentally friendly materials should be used compared to lead.

Die Aufgabe der Erfindung wird durch ein Blei-Ersatzmaterial für Strahlenschutzzwecke im Energiebereich einer Röntgenröhre mit einer Spannung von 60-140 kV gelöst, wobei das Blei-Ersatzmaterial 12-22 Gew.-% Matrixmaterial, 0-75 Gew.-% Zinn oder Zinnverbindungen, 0-73 Gew.-% Wolfram oder Wolframverbindungen, 0-80 Gew.-% Wismut oder Wismutverbindungen umfasst und wobei höchstens einer der Bestandteile 0 Gew.-% beträgt, wobei es sich bei diesem Bestandteil nicht um Wolfram oder die Wolframverbindung handelt. Die Mixtur erfasst Nenn-Gesamtbleigleichwerte von 0,25-2,0 mm.The object of the invention is a lead substitute material for radiation protection purposes in the energy sector an X-ray tube with a voltage of 60-140 kV, wherein the lead substitute material 12-22 wt .-% matrix material, 0-75 wt .-% tin or tin compounds, 0-73 wt .-% tungsten or tungsten compounds, 0- 80 wt .-% bismuth or bismuth compounds and wherein at most one of the components is 0 wt .-%, wherein this component is not tungsten or the tungsten compound. The mixture detects nominal total lead values of 0.25-2.0 mm.

Zur Lösung der Aufgabe war es deshalb erforderlich, eine Materialauswahl und deren Mengenauswahl aufzufinden, die die Röntgenstrahlung auch im hohen Energiebereich gut wirksam abschirmen kann.To solve the problem, it was therefore necessary to find a selection of materials and their quantity selection, which can shield the X-ray radiation well effective even in the high energy range.

In überraschender Weise wurde gefunden, dass sich die Absorptionswirkung bei hohen Energien durch hohe Anteile von Wolfram und/oder Wismut, wobei Wolfram immer anwesend ist, in dem Blei-Ersatzmaterial wesentlich verbessert.Surprisingly, it has been found that the absorption effect at high energies by high proportions of tungsten and / or bismuth, wherein tungsten is always present, significantly improved in the lead replacement material.

In einer bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass es 12-22 Gew.-% Matrixmaterial, 0-39 Gew.-% Sn oder Sn-Verbindungen, 0-60 Gew.-% W oder W-Verbindungen und 0-60 Gew.-% Bi oder Bi-Verbindungen umfasst und wobei höchstens einer der Bestandteile 0 Gew.-% beträgt, wobei es sich bei diesem Bestandteil nicht um Wolfram oder die Wolframverbindung handelt.In a preferred embodiment of the invention, the lead substitute material is characterized by having 12-22 wt% matrix material, 0-39 wt% Sn or Sn compounds, 0-60 wt% W or W compounds and 0-60% by weight of Bi or Bi compounds, and wherein at most one of the components is 0% by weight, which component is not tungsten or the tungsten compound.

In einer besonders bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass es 12-22 Gew.-% Matrixmaterial, 0-39 Gew.-% Sn oder Sn-Verbindungen, 16-60 Gew.-% W oder W-Verbindungen und 16-60 Gew.-% Bi oder Bi-Verbindungen umfasst.In a particularly preferred embodiment of the invention, the lead substitute material is characterized in that it contains 12-22% by weight of matrix 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.

In einer weiteren bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass es 12-22 Gew.-% Matrixmaterial, 40-60 Gew.-% Sn oder Sn-Verbindungen, 7-15 Gew.-% W oder W-Verbindungen und 7-15 Gew.-% Bi oder Bi-Verbindungen umfasst.In a further preferred embodiment of the invention, the lead substitute material is characterized in that it comprises 12-22% by weight matrix material, 40-60% by weight Sn or Sn compounds, 7-15% by weight W or W Compounds and 7-15 wt .-% Bi or Bi compounds.

In einer weiteren besonders bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass es zusätzlich bis 40 Gew.-% eines oder mehrerer der folgenden Elemente Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I und/oder ihrer Verbindungen und/oder CsI umfasst.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 Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd , Cs, Ba, I and / or their compounds and / or CsI.

In folgender Tabelle 1 sind die Massen-Schwächungskoeffizienten von Bleifrei-Schutzstoffen außerhalb der Absorptionskanten bei verschiedenen Photonenenergien dargestellt. Die bei der jeweiligen Energie vorteilhaft einzusetzenden Elemente sind unterstrichen. Tabelle 1 Energie (keV) Sn Gd Er W Bi 40 19,42 6,92 8,31 10,67 14,95 50 10,70 3,86 4,63 5,94 8,38 60 6,56 11,75 13,62 3,71 5,23 80 3,03 5,57 6,48 7,81 2,52 100 1,67 3,11 3,63 4,43 5,74 150 0,61 1,10 1,28 1,58 2.08 Table 1 below shows the mass attenuation coefficients of lead-free protective substances outside the absorption edges at different photon energies. The advantageous elements to be used for the respective energy are underlined. Table 1 Energy (keV) sn Gd He W Bi 40 19.42 6.92 8.31 10.67 14.95 50 10.70 3.86 4.63 5.94 8.38 60 6.56 11.75 13.62 3.71 5.23 80 3.03 5.57 6.48 7.81 2.52 100 1.67 3.11 3.63 4.43 5.74 150 0.61 1.10 1.28 1.58 2:08

Durch das Blei-Ersatzmaterial, das zusätzlich eines oder mehrere Elemente Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I und/oder ihrer Verbindungen und/oder CsI umfasst, wird eine besonders starke Zunahme der Absorptionswirkung erreicht. Auf diese Weise kann das Gewicht der Schutzkleidung wesentlich gesenkt werden.By the lead substitute material additionally comprising one or more elements Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I and / or their compounds and / or CsI is a reached a particularly strong increase in the absorption effect. In this way, the weight of the protective clothing can be significantly reduced.

Zur Erzielung der beschriebenen Eigenschaften können nach der Tabelle 1 die einzelnen Elemente so zusammengestellt werden, dass ein bestimmter Energiebereich abgedeckt wird oder dass sich ein möglichst gleichmäßiger Verlauf der Schwächung über einen größeren Energiebereich ergibt.To achieve the described properties, according to Table 1, the individual elements can be assembled so that a certain energy range is covered or that the most uniform course of the weakening results over a larger energy range.

In überraschender Weise wurde festgestellt, dass bei Einsatz der oben genannten zusätzlichen Elemente von deren Verbindungen bei dem Blei-Ersatzmaterial ein überproportionaler Anstieg der Schutzwirkung auftritt, vorzugsweise, wenn ihr Gewichtsanteil an dem Blei-Ersatzmaterial zwischen 20% und 40% beträgt.Surprisingly, it has been found that when using the above-mentioned additional elements of their compounds in the lead substitute material, a disproportionate increase in the protective effect occurs, preferably when their weight fraction of the lead substitute material is between 20% and 40%.

In einer weiteren bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass es zusätzlich bis 40 Gew.-% eines oder mehrerer der folgenden Elemente Ta, Hf, Lu, Yb, Tm, Th, U und/oder ihrer Verbindungen umfasst.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.

Bei den zusätzlich im Blei-Ersatzmaterial einsetzbaren Metallen Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Ba, I, Ta, Hf, Lu, Yb, Tm, Th, U können auch Metalle und/oder ihre Verbindungen und/oder CsI mit einem realtiv geringen Reinheitsgrad eingesetzt werden, wie sie als Abfallprodukte anfallen.In addition, in the lead substitute materials usable metals Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Ba, I, Ta, Hf, Lu, Yb, Tm, Th, U can also metals and / or their compounds and / or CsI be used with a relatively low degree of purity, as they arise as waste products.

In DIN EN 61331-3 ist eine Abweichung vom Nenn-Bleigleichwert nach unten nicht zugelassen. Lediglich die deutsche Fassung der Norm lässt eine Ausnahme zu, nämlich eine Abweichung von 10% vom Nenn-Bleigleichwert. Aus diesen Gründen ist ein möglichst flacher Verlauf des Bleigleichwerts über die Energie bei einem Blei-Ersatzmaterial anzustreben.In DIN EN 61331-3 a deviation from the nominal lead equivalent value downwards is not permitted. Only the German version of the standard allows one exception, namely a deviation of 10% from the nominal lead equivalent. For these reasons, it is desirable to have as flat a lead as possible over the energy of a lead substitute material.

Ein Absinken des Bleigleichwerts unter den Nenn-Bleigleichwert bzw. unter die untere Toleranzgrenze bedeutet, dass das Strahlenschutzmaterial bei den betreffenden Röhrenspannungen nicht genutzt werden kann, da die abschirmende Wirkung zu gering ist. In diesem Fall muss alternativ das Flächengewicht des Blei-Ersatzmaterials soweit erhöht werden, dass die zulässigen Toleranzen der DIN EN 61331-3 erfüllt werden. Eine Erhöhung des Flächengewichts wird jedoch als nachteilig angesehen.A fall in the lead equivalent below the nominal lead equivalent or below the lower tolerance limit means that the radiation protection material can not be used at the relevant tube voltages, since the shielding effect is too low. In this case, alternatively, the basis weight of the lead substitute material must be increased to the extent that the permissible tolerances of DIN EN 61331-3 are met. However, an increase in basis weight is considered disadvantageous.

Eine weitere Möglichkeit besteht in der Beschränkung des Anwendungsbereichs im Hinblick auf die Energie bzw. die Röhrenspannung.Another possibility is the limitation of the field of application with regard to the energy or the tube voltage.

Es war von daher ein weiteres Ziel vorliegender Erfindung, Elemente oder deren Verbindungen dergestalt auszuwählen, dass ein möglichst geringer Abfall des Bleigleichwerts im gewünschten Energienutzungsbereich erfolgt, unter Berücksichtigung der Zugänglichkeit der jeweiligen Elementen bzw. ihrer Verbindungen.It was therefore a further object of the present invention to select elements or their compounds in such a way that the lowest possible drop in the lead equivalent in the desired energy utilization range takes place, taking into account the accessibility of the respective elements or their compounds.

Die relative Wirskamkeit Nrei als Zunahme des Bleigleichwerts (PbGW) bezogen auf eine normierte Massenbelegung von 0,1 kg/m2 wurde bei einer Reihe von Materialien in Versuchsreihen ermittelt und in unten stehender Tabelle 2 zusammengefasst. Sie gibt die Schwächungseigenschaften der einzelnen Elemente noch deutlicher wieder als die oben beschriebenen Massen-Schwächungskoeffizienten, da hier die Absorption im unmittelbaren Bereich der jeweiligen Absorptionskanten mit einfließt. Tabelle 2 Material Nrei Mittlerer Zuwachs PbGW bezogen auf 0,1 kg/m2 (rel. Pb) Anstieg PbGW von 60 auf 80 kV bezogen auf 0,1 kg/m2 Gruppe 60-90 kV 60-125 kV 100-125 kV 125-150 kV Sn 1,64 1,30 0,96 0,80 -0,005 A Bi 1,41 1,27 1,13 1,17 -0,005 A W 0,91 1,07 1,25 1,07 +-0,000 A Gd 1,85 2,05 2,27 1,56 +0,007 B Er 1,20 1,45 1,70 1,36 +0,009 B The relative strength N rei as an increase in the lead equivalent (PbGW) relative to a normalized mass coverage of 0.1 kg / m 2 was determined in a series of materials in test series and summarized in Table 2 below. It reproduces the weakening 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 material N rei Mean growth PbGW based on 0.1 kg / m 2 (rel. Pb) PbGW increase from 60 to 80 kV based on 0.1 kg / m 2 group 60-90 kV 60-125 kV 100-125 kV 125-150 kV sn 1.64 1.30 0.96 0.80 -0,005 A Bi 1.41 1.27 1.13 1.17 -0,005 A W 0.91 1.07 1.25 1.07 + -0.000 A Gd 1.85 2.05 2.27 1.56 +0.007 B He 1.20 1.45 1.70 1.36 +0.009 B

In überraschender Weise zeigt sich hierbei, dass die Elemente oder deren Verbindungen wie folgt klassifiziert werden können: Gruppe A: Materialien mit relativ geringer Wirksamkeit mit Werten von Nrei<1,2 - 1-6 mm PbGW pro 0,1 kg/m2 und einem geringen bzw. negativen Anstieg von 60-80 kV. Zu diesen Elementen oder ihren Verbindungen zählen Sn, Bi und W. Gruppe B: Materialien mit relativ hoher Wirksamkeit mit Nrei ≥ 1,3 mm PbGW pro 0,1 kg/m2 und einem hohen Anstieg von 60-80 kV. Surprisingly, this shows that the elements or their compounds can be classified as follows: Group A: Relatively low efficiency materials with values of N rei <1.2 - 1-6 mm PbGW per 0.1 kg / m 2 and a small or negative increase of 60-80 kV. These elements or their compounds include Sn, Bi and W. Group B: Relatively high efficiency materials with N rei ≥ 1.3 mm PbGW per 0.1 kg / m 2 and a high rise of 60-80 kV.

In einer besonders bevorzugten Ausführungsform der Erfindung wird daher der Energiebereich 60-140 kV entsprechend den häufigsten Anwendungen der Röntgenstrahlung in mehrere, zum Teil überlappende, Bereiche aufgeteilt:In a particularly preferred embodiment of the invention, therefore, the energy range 60-140 kV is divided into several, partly overlapping, regions corresponding to the most common applications of the x-ray radiation:

1. Energiebereich 60-90 kV1. Energy range 60-90 kV

In diesem Energiebereich finden überwiegend zahnmedizinische Anwendungen der Einzelaufnahmetechnik und der Panorama-Schichttechnik statt.In this field of energy predominantly dental applications of the single-shot technique and the panoramic layer technique take place.

2. Energiebereich 60-125 kV2. Energy range 60-125 kV

In diesem Energiebereich liegen die häufigsten Röntgenuntersuchungen und Röntgeninterventionen, wie Angiografie, Computer-Tomografie, Herzkatheter-Untersuchungen, interventionelle Radiologie, Thorax-Hartstrahltechnik.This area of energy includes the most common X-ray examinations and X-ray interventions, such as angiography, computed tomography, cardiac catheter examinations, interventional radiology, thorax hard-beam technique.

3. Energiebereich 100-125 kV3. Energy range 100-125 kV

In diesen Energiebereich fallen die meisten Computer-Tomografen.Most computer tomographs fall into this energy range.

4. Energiebereich 125-150 kV4. Energy range 125-150 kV

Das ist ein Energiebereich für spezielle Anwendungen, wie spezielle Computer-Tomografen, Knochendichte-Messungen, Spezial-Thorax-Hartstrahltechnik und nuklearmedizinische Diagnostik.This is an energy range for specific applications such as special computed tomography, bone density measurements, special thorax hard-jet technology and nuclear medicine diagnostics.

Bleifreie Schutzkleidung, die nur in einem bestimmten Energiebereich Verwendung finden kann, ist vom Hersteller entsprechend zu kennzeichnen.Lead-free protective clothing that can only be used in a certain energy range must be marked accordingly by the manufacturer.

In einer Ausführungsform des Blei-Ersatzmaterials für Strahlenschutzzwecke im Energiebereich einer Röntgenröhre mit einer Spannung von 60-90 kV ist das Blei-Ersatzmaterial für Nenn-Gesamtbleigleichwerte von 0,25-0,6 mm dadurch gekennzeichnet, dass es 12-22 Gew.-% Matrixmaterial, 49-65 Gew.-% Sn oder Sn-Verbindungen, 0-20 Gew.-% W oder W-Verbindungen, 0-20 Gew.-% Bi oder Bi-Verbindungen und 2-35 Gew.-% eines oder mehrerer der Elemente Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I, Pr und/oder ihrer Verbindungen und/oder CsI umfasst, wobei W oder die W-Verbindung nicht O beträgt. Der Energiebereich ist vorzugsweise der einer Röntgenröhre eines Dental-Röntgengeräts.In one embodiment of the lead replacement material for radiation protection purposes in the energy range of an x-ray tube having a voltage of 60-90 kV, the lead substitute for nominal total lead equivalent of 0.25-0.6 mm is characterized by having 12-22 wt. % Matrix material, 49-65 wt% Sn or Sn compounds, 0-20 wt% W or W compounds, 0-20 wt% Bi or Bi compounds, and 2-35 wt% of one or more of the elements Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I, Pr and / or their compounds and / or CsI, wherein W or the W compound is not O. The energy range is preferably that of an X-ray tube of a dental X-ray machine.

In einer besonderen Ausführungsform der vorliegenden Erfindung umfasst das Blei-Ersatzmaterial 2-25 Gew.-% I, Cs, Ba, La, Ce, Pr und/oder Nd und/oder ihre Verbindungen und/oder CsI.In a particular embodiment of the present invention, the lead substitute material comprises 2-25% by weight of I, Cs, Ba, La, Ce, Pr and / or Nd and / or their compounds and / or CsI.

Bei dem relativ schmalen Energiebereich zeigte sich aus Tabelle 2, dass von den Gruppe A Elementen Sn am wirksamsten ist. Aus der Gruppe B ist Gd bevorzugt, wobei jedoch CsI ebenfalls zu einem Blei-Ersatzmaterial mit sehr guten Eigenschaften führte.In the relatively narrow energy range, it was shown from Table 2 that of the group A elements Sn is the most effective. From Group B Gd is preferred, but CsI also resulted in a lead substitute with very good properties.

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

Aus der Tabelle 2 können beispielsweise Elemente mit geringem und hohem Anstieg des Bleigleichwerts in vorteilhafter Weise in der Weise ausgewählt werden, dass die Verläufe des Bleigleichwerts über den gesamten Bereich möglichst flach bleiben. Eine gewisse Überhöhung bei 80 und 100 kV ist dabei physikalisch nicht zu umgehen.From Table 2, for example, elements with low and high rise of the lead equivalent in be advantageously selected in such a way that the curves of the lead equivalent remain as flat as possible over the entire range. A certain elevation at 80 and 100 kV is physically impossible to avoid.

Es können daher ein oder mehrere Elemente oder deren Verbindungen der Gruppe A mit einem oder mehreren Elementen oder deren Verbindungen der Gruppe B in optimaler Weise kombiniert werden, wobei die Auswahl nach der Effizienz der Abschirmung, nach der Zugänglichkeit des jeweiligen Elements oder dessen Verbindung und nach einem möglichst konstanten Verlauf des Bleigleichwerts erfolgt.Thus, one or more elements or their compounds of group A can be optimally combined with one or more elements or their compounds of group B, the choice being made according to the efficiency of the shield, the accessibility of the element or its compound and As constant as possible of the lead equivalent takes place.

Hierbei ist eine Abhängigkeit des Anteils der A-Elemente oder ihrer Verbindungen von denjenigen der B-Elemente oder ihrer Verbindungen gegeben. So muss bei einer Erhöhung des Anteils eines B-Elements auch der relative Gewichtsanteil eines A-Elements mit entgegengesetztem Energieverhalten deutlich erhöht werden, um den Verlauf des Bleigleichwerts über die Energie möglichst flach zu halten.Here, a dependence of the proportion of the A elements or their compounds is given by those of the B elements or their compounds. Thus, when increasing the content of a B-element, the relative weight fraction of an A-element with opposite energy behavior must also be significantly increased in order to keep the course of the lead equivalent above the energy as flat as possible.

Beispielsweise sollte bei einem Anteil von über 20 Gew.-% an B-Elementen oder deren Verbindungen der Anteil an Sn oder Bi über 40 Gew.-% steigen, um eine geringe Energieabhängigkeit sicherzustellen.For example, if more than 20% by weight of B-elements or their compounds, the proportion of Sn or Bi should exceed 40% by weight to ensure low energy dependence.

Energiebereich 100-140 kV:Energy range 100-140 kV:

Das ist der Energiebereich für die meisten neueren Computer-Tomografen.This is the energy range for most recent computer tomographs.

In einer besonders bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial für Strahlenschutzzwecke im Energiebereich einer Röntgenröhre mit einer Spannung von 100-140 kV dadurch gekennzeichnet, dass das Blei-Ersatzmaterial für Nenn-Gesamtbleigleichwerte von 0,2 5-0,6 mm 12-22 Gew.-% Matrixmaterial, 40-73 Gew.-% Bi und/oder W oder ihre Verbindungen (wobei W immer answesend ist), und 5-38 Gew.-% eines oder mehrere der folgenden Elemente Gd, Eu, Er, Hf und/oder ihrer Verbindungen umfasst.In a particularly preferred embodiment of the invention, the lead replacement material for radiation protection purposes in the energy range of an X-ray tube with a voltage of 100-140 kV is characterized in that the lead replacement material for nominal total lead equivalent values of 0.2 5-0.6 mm 12- 12. 22 wt .-% matrix material, 40-73 wt .-% Bi and / or W or their compounds (where W is always answesend), and 5-38 wt .-% of one or more of comprises the following elements Gd, Eu, Er, Hf and / or their compounds.

Hoche Schutzwirkungen bzw. geringe Flächengewichte können durch Einsatz der Elemente oder ihrer Verbindungen erzielt werden, die speziell in diesem kleinen Energiebereich ihre höchste Abschirmwirkung entfalten. Aus Gründen der Zugänglichkeit sollte ein größerer Anteil aus den Elementen oder ihren Verbindungen der Gruppe A mit einem kleineren Anteil der Elemente oder ihrer Verbindungen der Gruppe B kombiniert werden, wobei in diesem Fall ein flacher Energiegang des Bleigleichwertes wegen des relativ kleinen Energiefensters hier nicht so wesentlich ist.High protective effects or low basis weights can be achieved by using the elements or their compounds, which have their highest shielding effect especially in this small energy range. For reasons of accessibility, a greater proportion of the elements or their group A compounds should be combined with a smaller proportion of the elements or their group B compounds, in which case a flat energy balance of the lead equivalent will not be so important because of the relatively small energy window is.

Energiebereich 125-150 kV:Energy range 125-150 kV:

Dieser Bereich betrifft Sonderanwendungen in der Radiologie und Nuklearmedizin. Das Flächengewicht der Strahlenschutzschürze steht in diesem Bereich nicht im Vordergrund der Optimierung, da die Schutzkleidung in der Regel hier nur für kurze Zeit getragen wird oder ortsfeste Strahlenschutzschirme Verwendung finden.This area concerns special applications in radiology and nuclear medicine. The weight per unit area of the radiation protection apron is not in the foreground of the optimization in this area since the protective clothing is generally worn here only for a short time or stationary radiation protection screens are used.

Die Auswahl der Elemente oder ihrer Verbindungen geschieht nach den oben genannten Kriterien. Sehr gute Ergebnisse liefern Gd und Er in Kombination mit Bi. Die Wirkung von W ist in diesem Bereich zu gering.The selection of the elements or their connections is done according to the above criteria. Gd and Er provide very good results in combination with Bi. The effect of W is too low in this area.

Zusammenfassend lässt sich also feststellen, dass die Zusammensetzung von Schutzstoffen für einzelne Energiebereiche entsprechend den am häufigsten vorkommenden Röntgenanwendungen zweckmäßigerweise durch Aufspaltung optimiert werden kann.In summary, it can thus be stated that the composition of protective substances for individual energy ranges can be expediently optimized by splitting according to the most frequently occurring X-ray applications.

In einer weiteren bevorzugten Ausführungsform der Erfindung weist das Blei-Ersatzmaterial einen Aufbau aus mindestens zwei getrennten oder miteinander verbundenen Schutzschichten unterschiedlicher Zusammensetzung auf, wobei mindestens bei einer Schicht mindestens 50% des Gesamtgewichts nur aus einem Element aus der Gruppe Sn, W und Bi oder deren Verbindungen besteht.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 composition, wherein 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.

Insbesondere weist das Blei-Ersatzmaterial einen Aufbau aus mindestens zwei getrennten oder miteinander verbundenen Schutzschichten unterschiedlicher Zusammensetzung auf, wobei mindestens bei einer Schicht mindestens 50% des Gesamtgewichts nur aus mindestens 40 Gew.-% Sn oder dessen Verbindungen und mindestens 10 Gew.-% I, Cs, Ba, La, Ce, Pr und/oder Nd und/oder ihren Verbindungen und/oder CsI besteht. Besonders vorteilhaft ist eine Schicht, die 40 bis 50 Gew.-% Sn und 10 bis 20 Gew.-% Cer umfasst.In particular, the lead substitute material has a structure of at least two separate or interconnected protective layers of different composition, wherein at least one layer at least 50% of the total weight only of at least 40 wt .-% Sn or its compounds and at least 10 wt .-% I. , Cs, Ba, La, Ce, Pr and / or Nd and / or their compounds and / or CsI. Particularly advantageous is a layer comprising 40 to 50 wt .-% Sn and 10 to 20 wt .-% cerium.

In einer weiteren bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass es einen Aufbau aus mindestens zwei getrennten oder miteinander verbundenen Schutzschichten unterschiedlicher Zusammensetzung umfasst, wobei (die) vom Körper entferntere Schutzschicht(en) überwiegend die Elemente oder deren Verbindungen mit höherer Röntgen-Fluoreszenzausbeute und die körpernahe(n) Schutzschicht(en) die Elemente oder deren Verbindungen mit geringerer Röntgen-Fluoreszenzausbeute umfassen.In a further preferred embodiment of the invention, the lead substitute material is characterized in that it comprises a construction of at least two separate or interconnected protective layers of different composition, wherein the protective layer (s) removed from the body predominantly the elements or their compounds with higher X-ray fluorescence yield and the body-near protective layer (s) comprise the elements or their compounds with lower X-ray fluorescence yield.

Bei der Bestrahlung von Materialien mit Röntgenstrahlung wird charakteristische Röntgenstrahlung als Fluoreszenzstrahlung angeregt. Die Fluoreszenzausbeute hängt von der Ordnungszahl ab. Dieser Fluoreszenzanteil führt zu einer zusätzlichen Strahlenexposition der Haut und der unmittelbar darunter liegenden Organe. Aus Messungen an Schutzkleidung wurde ermittelt, dass insbesondere Elemente mit kleineren Ordnungszahlen, im vorliegenden Fall also insbesondere Sn, besonders stark fluoreszieren. Bei einem geschichteten Aufbau des Strahlenschutzmaterials kann in vorteilhafter Weise eine Schichtung nach Elementen so erfolgen, dass die Elemente mit geringster Fluoreszenzausbeute auf der Hautseite liegen.In the irradiation of materials with X-rays, characteristic X-radiation is excited as fluorescence radiation. The fluorescence yield depends on the atomic number. This fluorescence content leads to an additional radiation exposure of the skin and the organs immediately below it. From measurements on protective clothing it was determined that in particular elements with smaller atomic numbers, in the present case in particular Sn, fluoresce particularly strongly. In the case of a layered structure of the radiation protection material, stratification according to elements can advantageously take place such that the elements lie on the skin side with the lowest possible fluorescence yield.

Der Fluoreszenzanteil, auch als build-up-Faktor bezeichnet, ist von marktüblichen bleifreien Schutzmaterialien (Material B) in der folgenden Tabelle 3 im Vergleich zu einem nach dem hier beschriebenen Prinzip schichtweise aufgebauten Material (Material A) dargestellt. Wie ersichtlich, kann der build-up-Faktor Werte bis 1,42 erreichen. D.h., die Haut wird in diesem Fall durch den Fluoreszenzanteil um 42% mehr belastet. Tabelle 3 kV Material A Material B 80 1,15 1,42 90 1,14 1,35 100 1,14 1,32 110 1,16 1,36 The fluorescence component, also referred to as build-up factor, is represented by commercially available lead-free protective materials (material B) in the following Table 3 in comparison with a material constructed in layers according to the principle described here (material A). As can be seen, the build-up factor can reach values up to 1.42. That is, the skin is burdened in this case by the fluorescent component by 42% more. Table 3 kV Material A Material B 80 1.15 1.42 90 1.14 1.35 100 1.14 1.32 110 1.16 1.36

In einer weiteren besonders bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass es einen Aufbau aus Schutzschichten unterschiedlicher Zusammensetzung aufweist.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 composition.

Das Blei-Ersatzmaterial kann einen Aufbau aus mindestens zwei getrennten oder miteinander verbundenen Schutzschichten unterschiedlicher Zusammensetzung umfassen, wobei die vom Körper entferntere(n) Schutzschicht(en) überwiegend die Elemente niedrigerer Ordnungszahl oder deren Verbindungen und die körpernahe(n) Schutzschicht(en) überwiegend die Elemente höherer Ordnungszahl oder deren Verbindungen umfassen.The lead substitute material may comprise a construction of at least two separate or interconnected protective layers of different composition, with the body-removed protective layer (s) predominantly comprising the lower atomic number elements or their compounds and the proximal protective layer (s) comprise the elements of higher atomic number or their compounds.

Das Blei-Ersatzmaterial kann auch einen Aufbau aus mindestens drei getrennten oder miteinander verbundenen Schutzschichten unterschiedlicher Zusammensetzung aufweisen, wobei die vom Körper entferntere(n) Schutzschicht(en) und die körpernahe(n) Schutzschicht(en) überwiegend die Elemente höherer Ordnungszahlen oder derer Verbindungen umfassen und in der Mitte mindestens eine Schutzschutz mit überwiegend Elementen niedriger Ordnungszahlen angeordnet ist.The lead substitute material may also have a construction of at least three separate or interconnected protective layers of different composition, the more remote from the body protective layer (s) and the near-main (s) protective layer (s) predominantly the elements of higher atomic numbers or their compounds include and in the middle at least one Protection with predominantly elements of low atomic numbers is arranged.

Somit befindet sich beispielsweise außen beiderseits eine Sperrschicht aus einem Material höherer Ordnungszahlen, wie beispielsweise Bismut oder Wolfram. Dazwischen liegt eine Schicht oder es liegen Schichten aus einem Material mit niedrigerer Ordnungszahl. Die dort entstehende Fluoreszenzstrahlung wird also nach beiden Seiten hin wirksam abgeschirmt und kann nicht nach außen dringen.Thus, for example, on both sides outside a barrier layer of a material of higher atomic numbers, such as bismuth or tungsten. In between lies a layer or layers of a material with a lower atomic number. The resulting fluorescence radiation is thus effectively shielded on both sides and can not penetrate to the outside.

Alternativ dazu kann auch ein Schichtaufbau aus mindestens einer hochkonzentrischen, verdichtenden Pulverschicht aus einer Mischung der obengenannten Schutzstoffe und mindestens zwei Trägerschichten beidseitig der Pulverschicht vorgesehen werden. Die Pulverschicht enthält möglichst wenig Matrixmaterial. Die Trägerschichten können aus Matrixmaterial zusammengesetzt sein. Geeignete Materialien sind beispielsweise Polymere, wie Latex oder Elastomere. Die Trägerschichten erhöhen die mechanische Stabilität, während die konzentrierte Füllung die strahlenabschirmende Wirkung verbessert. Figur 4 zeigt diesen Schichtaufbau mit einer hochverdichteten Schutzstoffschicht 2 als Kern und den außenliegenden Trägerschichten 1.Alternatively, a layer structure of at least one highly concentric, compacting powder layer of a mixture of the abovementioned protective substances and at least two carrier layers can be provided on both sides of the powder layer. The powder layer contains as little matrix material as possible. The carrier layers may be composed of matrix material. Suitable materials include polymers such as latex or elastomers. The carrier layers increase the mechanical stability, while the concentrated filling improves the radiation-shielding effect. FIG. 4 shows this layer structure with a highly compressed protective material layer 2 as the core and the outer carrier layers 1.

Das Blei-Ersatzmaterial kann auch dadurch gekennzeichnet sein, dass eine schwach radioaktive Schicht zwischen zwei getrennten oder mit der radioaktiven Schicht verbundenen nichtradioaktiven Schutzschichten eingebettet ist.The lead substitute material may also be characterized in that a weakly radioactive layer is embedded between two separate or nonradioactive protective layers connected to the radioactive layer.

Es können als Elemente oder deren Verbindungen der Gruppe B zur Abschirmung von Strahlung hoher Energie auch die Actinoiden Thorium oder Uran, letzteres z. B. als abgereichertes Uran, eingesetzt werden. Sie besitzen eine hohe Abschirmwirkung im Energiebereich 125-150 kV, sind jedoch selbst schwach radioaktiv.It can be used as elements or their compounds of group B to shield high energy radiation and the actinides thorium or uranium, the latter z. B. as depleted uranium, are used. They have a high shielding effect in the energy range of 125-150 kV, but are themselves weakly radioactive.

Der Effekt der Eigenstrahlung kann dadurch abgeschwächt werden, dass die radioaktive Schicht zwischen zwei nicht aktive Schichten aus Bi eingebettet ist. Der Anteil der Eigenexposition durch Thorium oder Uran sollte in den meisten Fällen gering und damit zu vernachlässigen sein. Es hat hier eine Vorteilsabwägung stattzufinden, die die Vorteile, die durch die Eliminierung von Blei und durch die höhere Schutzwirkung entstehen, der geringen Eigenexposition gegenüberzustellen sind.The effect of self-radiation can be mitigated by embedding the radioactive layer between two non-active layers of Bi. The proportion of self-exposure by thorium or uranium should be low in most cases and therefore negligible. There is a trade-off here, which contrasts the benefits of lead elimination and higher protection with low intrinsic exposure.

In einer weiteren bevorzugten Ausführungsform der Erfindung ist das Blei-Ersatzmaterial dadurch gekennzeichnet, dass die Metalle oder Metallverbindungen gekörnt sind und deren Korngrößen eine 50er Perzentile nach folgender Formel D 50 = d ⋅ p 10 ⁢ mm

Figure imgb0001
aufweisen, worin D 50 die 50er-Perzentile der Korngrößenverteilung, d die Schichtdicke in mm und p den Gewichtsanteil der jeweiligen Materialkomponente am Gesamtgewicht bedeuten und die 90er Perzentile der Korngrößenverteilung D90 ≤ 2 · D50 ist.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 a 50th percentile according to the following formula D 50 = d ⋅ p 10 ⁢ mm
Figure imgb0001
 where D 50 is the 50th percentile of the particle size distribution, d is the layer thickness in mm and p is the weight fraction of the respective material component in the total weight and the 90th percentile of the particle size distribution D 90 ≦ 2 * D 50 .

Bei den Messungen der Bleigleichwerte an Schutzschichten, die aus Metallpulvern oder Pulvern von Metallverbindungen bestehen, stellte sich in überraschender Weise heraus, dass die Strahlendurchlässigkeit der aus gekörnten Substanzen bestehenden Schicht im Vergleich zu einer Folienschicht bei gleicher Massenbelegung höher ist. Dies betrifft hauptsächlich den unteren Energiebereich von 60-80 kV. Bei höheren Energien werden die lokalen Durchlässigkeitsunterschiede, d.h. der Röntgenkontrast, zunehmend geringer.In the measurements of the lead equivalents on protective layers, which consist of metal powders or powders of metal compounds, it surprisingly turned out that the radiation permeability of the layer consisting of granular substances 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 transmission differences, i. the X-ray contrast, increasingly lower.

Beispielsweise ergibt sich bei einem Sn-Anteil von 30% = 0,3 und einer Schichtdicke von 0,4 mm D 50 = 0 , 4 ⁢ mm ⋅ 0 , 3 = 0 , 012 ⁢ mm = 12 ⁢ μm .

Figure imgb0002
For example, with an Sn content of 30% = 0.3 and a layer thickness of 0.4 mm D 50 = 0 . 4 ⁢ mm ⋅ 0 . 3 = 0 . 012 ⁢ mm = 12 ⁢ microns ,
Figure imgb0002

Die 90er Perzentile der Korngrößenverteilung sollte darüber hinaus nicht größer als 2·D 50 = 24µm sein.In addition, the 90th percentile of the particle size distribution should not be greater than 2 · D 50 = 24 μm.

Materialien mit geringem Gewichtsanteil müssen daher auch eine geringe Korngröße besitzen, d.h. sehr fein verteilt sein, um eine optimale Schutzwirkung zu entfalten.Therefore, low weight materials must also have a small grain size, i. be very finely distributed to develop an optimal protective effect.

Bei Ausnutzung dieses Effekts kann das Gewicht einer Strahlenschutzschürze noch weiter reduziert werden.By taking advantage of this effect, the weight of a radiation protection apron can be further reduced.

Das erfindungsgemäße Material kann beispielsweise bei Schutzhandschuhen, Patientenabdeckungen, Gonadenschutz, Ovarienschutz, Dentalschutzschilde, ortsfestem Unterkörperschutz, Tischaufsätzen, ortsfesten oder ortsbeweglichen Strahlenschutzwänden oder Strahlenschutzvorhängen vorteilhaft angewandt werden.The material of the invention can be used advantageously for example in protective gloves, patient covers, gonadal protection, ovarian protection, dental shields, fixed lower body protection, table tops, stationary or portable radiation protection walls or radiation curtains.

Im Folgenden soll die Erfindung anhand von Beispielen näher erläutert werden.In the following, the invention will be explained in more detail by way of examples.

Beispiel 1example 1

Die Fig. 1 zeigt das erfindungsgemäße Blei-Ersatzmaterial mit 22 Gew.-% Zinn, 27 Gew.-% Wolfram, 4 Gew.-% Erbium und 15 Gew.-% Matrixmaterial. Dieses Blei-Ersatzmaterial ist in der Fig. 1 mit 2 bezeichnet. Mit 1 ist ein marktübliches Material der Zusammensetzung 65 Gew.-% Antimon, 20 Gew.-% Wolfram und 15 Gew.-% Matrixmaterial bezeichnet.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 matrix material. This lead substitute material is designated 2 in FIG. 1. 1 denotes a commercially available material of the composition 65% by weight of antimony, 20% by weight of tungsten and 15% by weight of matrix material.

Die Fig. 1 zeigt einen Gewichtsvergleich von Blei-Ersatzmaterialien bei einem Nenn-Bleigleichwert von 0,5 mm.Fig. 1 shows a weight comparison of lead substitutes with a nominal lead equivalent of 0.5 mm.

Aus der Fig. 1 ist ersichtlich, dass das zum Erreichen eines Nenn-Bleigleichwerts von 0,5mm erforderliche Flächengewicht zwischen 100 und 140 kV bei dem erfindungsgemäßen Material nur um etwa 7% zunimmt, während die Zunahme bei dem Vergleichsmaterial erheblich größer ist.From Fig. 1 it can be seen that the required to achieve a nominal lead equivalent of 0.5 mm basis weight between 100 and 140 kV in the material according to the invention increases only by about 7%, while the increase in the comparison material is considerably greater.

Beispiel 2Example 2

Die Fig. 2 zeigt das erfindungsgemäße Blei-Ersatzmaterial mit 20 Gew.-% Zinn, 36 Gew.-% Wolfram, 29 Gew.-% Wismut und 15 Gew.-% Matrixmaterial. Dieses Blei-Ersatzmaterial ist in der Fig. 2 mit 2 bezeichnet. Mit 1 ist ein marktübliches Material der Zusammensetzung 70 Gew.-% Zinn, 10 Gew.-% Barium und 20 Gew.-% Matrixmaterial bezeichnet.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 matrix material. This lead substitute material is designated 2 in FIG. 1 denotes a commercially available material of the composition 70% by weight of tin, 10% by weight of barium and 20% by weight of matrix material.

Die Fig. 2 zeigt einen Gewichtsvergleich von Blei-Ersatzmaterialien bei einem Nenn-Bleigleichwert von 0,5 mm.Fig. 2 shows a weight comparison of lead substitutes with a nominal lead equivalent of 0.5 mm.

Aus der Fig. 2 ist ersichtlich, dass das zum Erreichen eines Nenn-Bleigleichwerts von 0,5 mm erforderliche Flächengewicht zwischen 100 und 140 kV bei einem erfindungsgemäßen Material nur um etwa 9% zunimmt, während die Zunahme bei dem Vergleichsmaterial ca. 60% beträgt.From Fig. 2 it can be seen that the required to achieve a nominal lead equivalent of 0.5 mm basis weight between 100 and 140 kV for a material according to the invention increases only by about 9%, while the increase in the comparison material is about 60% ,

Beispiel 3Example 3

Bleifreie, leichte Strahlenschutzschürze für den Dentalbereich von 60-90 kV Pb-Nennbleigleichwert 0,5 mm.Lead-free, light radiation protection apron for the dental sector of 60-90 kV Pb nominal lead equivalent 0.5 mm.

Es wurde eine bleifreie Strahlenschutzschürze aus 59 Gew.-% Sn, 24 Gew.-% Gd, 1 Gew.-% W und 16 Gew.-% Matrixmaterial hergestellt.A lead-free radiation protection apron was produced from 59% by weight Sn, 24% by weight Gd, 1% by weight W and 16% by weight matrix material.

Die Strahlenschutzwirkung entsprach derjenigen einer entsprechenden Bleischürze bei einem um etwa 35% verminderten Flächengewicht von nur 4,4 kg/m2.The radiation protection effect corresponded to that of a corresponding lead apron with a reduced basis weight of only 4.4 kg / m 2 by about 35%.

Beispiel 4Example 4

Bleifreie leichte Strahlenschutzschürze für den Anwendungsbereich 60-125 kV.Lead-free lightweight radiation protection apron for the application range 60-125 kV.

Es wurde eine Strahlenschutzschürze aus 50 Gew.-% Sn, 11 Gew.-% W, 23 Gew.-% Gd und 16 Gew.-% Matrixmaterial hergestellt.A radiation protection apron was made from 50% by weight Sn, 11% by weight W, 23% by weight Gd and 16% by weight matrix material.

Hierbei ergaben sich für einen Nenn-Bleigleichwert von 0,5 mm Blei ein Flächengewicht von 4,5 kg/m2, für einen Nenn-Bleigleichwert von 0,35 mm Blei ein Flächengewicht von 3,3 kg/m2 und ein Nenn-Bleigleichwert von 0,25 mm Blei ein Flächengewicht von 2,4 kg/m2.This resulted in a basis weight of 4.5 kg / m 2 for a nominal lead equivalent of 0.5 mm lead, and 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 a basis weight of 2.4 kg / m 2 .

Beispiel 5Example 5

Bleifreie leichte Strahlenschürze für die Computer-Tomografie.Lead-free lightweight radiation apron for computer tomography.

Es wurde eine Strahlenschutzschürze aus 40 Gew.-% Bi, 10 Gew.-% W, 34 Gew.-% Gd und 16 Gew.-% Matrixmaterial hergestellt.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 matrix material.

Es ergab sich ein überraschend niedriges Flächengewicht von 0,5 mm Nenn-Bleigleichwert von nur 4,6 kg/m2.The result was a surprisingly low basis weight of 0.5 mm nominal lead equivalent of only 4.6 kg / m 2 .

Beispiel 6Example 6

Die Fig. 3 zeigt die berechneten relativen Flächengewichte der erfindungsgemäßen Schutzkleidung mit Nenn-Bleigleichwerten von 0,5 mm gemäß den Beispielen 3, 4 und 5 im Vergleich zu einer Bleischürze mit 0,5 mm Bleigleichwert. Aus der Darstellung ist ersichtlich, dass die Schutzschürzen für Dentalanwendung, allgemeines Röntgen und Computer-Tomografie (CT) jeweils in den vorgesehenen Energiebereichen geringstes Flächengewicht aufweisen.FIG. 3 shows the calculated relative basis weights of the protective clothing according to the invention with nominal lead equivalents of 0.5 mm according to Examples 3, 4 and 5 in comparison with a lead apron with 0.5 mm lead equivalent. From the illustration it can be seen that the protective aprons for dental application, general X-ray and computer tomography (CT) each have the lowest basis weight in the envisaged energy ranges.

Arbeitet der Anwender bei Röhrenspannungen von 80-100 kV ist zudem der Bleigleichwert um ca. 20% über dem Nennwert von 0,5 mm Pb einer entsprechenden Bleichschürze. Dies bedeutet einen zusätzlichen erhöhten Strahlenschutz.In addition, if the user is working with tube voltages of 80-100 kV, the lead equivalent value is approximately 20% higher than the nominal value of 0.5 mm Pb of a corresponding bleaching apron. This means an additional increased radiation protection.

Beispiel 7Example 7

Bleifreie leichte Schürze im Energiebereich von 60 bis 120 kV mit Zweischichtaufbau.Lead-free lightweight apron in the energy range from 60 to 120 kV with two-layer construction.

Der Matrixanteil beträgt 15 Gew.-%.The matrix content is 15% by weight.

Folgende Zusammensetzung der Schutzstoffmaterialschichten wurde gewählt: Schicht Element/Verbindung Materialgewicht (kg/m2) Fluoreszenzschicht (außen) Sn 1,20 Gd (oxid) 0,72 Cer (oxid) 0,48 Sperrschicht (innen) Bi 1,44 W 0,48 Gd (oxid) 0,48 The following composition of protective material layers was chosen: layer Element / compound Material weight (kg / m 2 ) Fluorescent layer (outside) sn 1.20 Gd (oxide) 0.72 Cerium (oxide) 0.48 Barrier layer (inside) Bi 1.44 W 0.48 Gd (oxide) 0.48

Es ergab sich ein niedriges Flächengewicht von nur 4,8 kg/m2 für einen Bleigleichwert von 0,5 mm.The result was a low basis weight of only 4.8 kg / m 2 for a lead equivalent of 0.5 mm.

Claims (22)

  1. Lead substitute material for radiation protection purposes in the energy range of an X-ray tube having a voltage of from 60 to 140 kV, wherein for nominal overall lead equivalents of from 0.25 to 2.0 mm the lead substitute material comprises
    from 12 to 22 wt.% matrix material,
    from 0 to 75 wt.% Sn or Sn compounds,
    from 0 to 73 wt.% W or W compounds,
    from 0 to 80 wt.% Bi or Bi compounds, and
    wherein not more than one of the constituents is 0 wt.%,
    wherein that constituent is not W or the W compound.
  2. Lead substitute material according to claim 1,
    characterised in that
    the lead substitute material comprises
    from 12 to 22 wt.% matrix material,
    from 0 to 39 wt.% Sn or Sn compounds,
    from 0 to 60 wt.% W or W compounds and
    from 0 to 60 wt.% Bi or Bi compounds, and
    wherein not more than one of the constituents is 0 wt.%.
  3. Lead substitute material according to claim 2,
    characterised in that
    the lead substitute material comprises
    from 12 to 22 wt.% matrix material,
    from 0 to 39 wt.% Sn or Sn compounds,
    from 16 to 60 wt.% W or W compounds and
    from 16 to 60 wt.% Bi or Bi compounds.
  4. Lead substitute material according to claim 1,
    characterised in that
    the lead substitute material comprises
    from 12 to 22 wt.% matrix material,
    from 40 to 60 wt.% Sn or Sn compounds,
    from 7 to 15 wt.% W or W compounds and
    from 7 to 15 wt.% Bi or Bi compounds.
  5. Lead substitute material according to any one of claims 1 to 4,
    characterised in that
    the lead substitute material additionally comprises up to 40 wt.% of one or more of the following elements: Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I, Pr and/or their compounds and/or CsI.
  6. Lead substitute material according to claim 5,
    characterised in that
    the lead substitute material additionally comprises up to 20 wt.% of one or more of the following elements: Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I, Pr and/or their compounds and/or CsI.
  7. Lead substitute material according to claim 6,
    characterised in that
    the lead substitute material additionally comprises up to 8 wt.% of one or more of the following elements: Er, Ho, Dy, Tb, Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I, Pr and/or their compounds and/or CsI.
  8. Lead substitute material according to any one of claims 1 to 7,
    characterised in that
    the lead substitute material additionally comprises up to 40 wt.% of one or more of the following elements: Ta, Hf, Lu, Yb, Tm, Th, U and/or their compounds.
  9. Lead substitute material according to claim 8,
    characterised in that
    the lead substitute material additionally comprises up to 20 wt.% of one or more of the following elements: Ta, Hf, Lu, Yb, Tm, Th, U and/or their compounds.
  10. Lead substitute material according to claim 9,
    characterised in that
    the lead substitute material additionally comprises up to 8 wt.% of one or more of the following elements: Ta, Hf, Lu, Yb, Tm, Th, U and/or their compounds.
  11. Lead substitute material for radiation protection purposes in the energy range of an X-ray tube having a voltage of from 60 to 90 kV according to any one of claims 5 to 10,
    characterised in that
    for nominal overall lead equivalents of from 0.25 to 0.6 mm the lead substitute material comprises
    from 12 to 22 wt.% matrix material,
    from 49 to 65 wt.% Sn or Sn compounds,
    from 0 to 20 wt.% W or W compounds,
    from 0 to 20 wt.% Bi or Bi compounds and
    from 2 to 35 wt.% of one or more of the elements Gd, Eu, Sm, La, Ce, Nd, Cs, Ba, I, Pr and/or their compounds and/or CsI.
  12. Lead substitute material according to claim 11,
    characterised in that
    the lead substitute material comprises from 2 to 25 wt.% I, Cs, Ba, La, Ce, Pr and/or Nd and/or their compounds and/or CsI.
  13. Lead substitute material for radiation protection purposes in the energy range of an X-ray tube having a voltage of from 100 to 140 kV according to any one of claims 5 to 10,
    characterised in that
    for nominal overall lead equivalents of from 0.25 to 0.6 mm the lead substitute material comprises
    from 12 to 22 wt.% matrix material,
    from 40 to 73 wt.% Bi and/or W or their compounds and
    from 5 to 38 wt.% of one of more of the following elements: Gd, Eu, Er, Hf and/or their compounds.
  14. Lead substitute material according to any one of claims 1 to 13,
    characterised in that
    it comprises a structure of protective layers of different compositions.
  15. Lead substitute material according to claim 14,
    characterised in that
    it comprises a structure of at least two protective layers of different compositions which are separate or joined together, wherein the protective layer(s) more remote from the body comprise(s) predominantly the elements having a lower atomic number, or their compounds, and the protective layer(s) close to the body comprise(s) predominantly the elements having a higher atomic number, or their compounds.
  16. Lead substitute material according to claim 14 or 15,
    characterised in that
    it comprises a structure of at least two protective layers of different compositions which are separate or joined together, wherein at least in one layer at least 50% of the total weight consists of only one element from the group Sn, W and Bi or their compounds.
  17. Lead substitute material according to claim 14 or 15,
    characterised in that
    it comprises a structure of at least two protective layers of different compositions which are separate or joined together, wherein at least in one layer at least 50% of the total weight consists only of at least 40 wt.% Sn or its compounds and at least 10 wt.% I, Cs, Ba, La, Ce, Pr and/or Nd and/or their compounds and/or CsI.
  18. Lead substitute material according to claim 14,
    characterised in that
    it comprises a structure of at least two protective layers of different compositions which are separate or joined together, wherein the protective layer(s) more remote from the body comprise(s) predominantly the elements or their compounds having a higher X-ray fluorescent yield, and the protective layer(s) close to the body comprise(s) the elements or their compounds having a lower X-ray fluorescent yield.
  19. Lead substitute material according to any one of claims 14 to 18,
    characterised in that
    it comprises a structure of at least three protective layers of different compositions which are separate or joined together, wherein the protective layer(s) more remote from the body and the protective layer(s) close to the body comprise predominantly the elements having a higher atomic number or their compounds, and there is arranged in the middle at least one protective layer comprising predominantly elements having a lower atomic number.
  20. Lead substitute material according to any one of claims 14 to 20,
    characterised in that
    a weakly radioactive layer is embedded between two nonradioactive protective layers which are separate from or joined to the radioactive layer.
  21. Lead substitute material according to any one of claims 1 to 20,
    characterised in that
    the metals or metal compounds are granular and their particle sizes exhibit a 50th percentile according to the following formula D 50 = d ⋅ p 10 ⁢ mm
    Figure imgb0004
    wherein
    D50 represents the 50th percentile of the particle size distribution,
    d represents the layer thickness in mm and
    p represents the proportion by weight of the particular material component in the total weight,
    and the 90th percentile of the particle size distribution D 90 ≤ 2 · D 50.
  22. Radiation protection apron of lead substitute material according to any one of claims 1 to 21.
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US7449705B2 (en) 2008-11-11
EP1536732A1 (en) 2005-06-08
EP1540663A1 (en) 2005-06-15
ES2286663T3 (en) 2007-12-01
DE502004004129D1 (en) 2007-08-02
EP1540663B1 (en) 2008-11-26
US20060151750A1 (en) 2006-07-13
JP2007504451A (en) 2007-03-01
WO2005024846A1 (en) 2005-03-17
US20090230334A1 (en) 2009-09-17
US20060049384A1 (en) 2006-03-09
WO2005023116A1 (en) 2005-03-17

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