Titelaufnahme

Titel
Strahlenschutz im Medizinbau
Weitere Titel
Structural Radiation Protection in Healthcare-Buildings
AutorInnenZwinz, Bernhard
GutachterPöhn, Christian
Erschienen2014
Datum der AbgabeJuni 2014
SpracheDeutsch
DokumenttypBachelorarbeit
Schlagwörter (DE)Abschirmung / Abstandsgesetz / Barytbeton / Dosis / Grenzwerte / Nuklearmedizin / Radioaktivität / Röntgenstrahlung / Sekundärstrahlung
Schlagwörter (EN)shielding / inverse-square law / barite-concrete / dose / limit / nuclear-medicine / radioactivity / x-rays / secondary radiation
Zugriffsbeschränkung
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Klassifikation
Zusammenfassung (Deutsch)

Diese Arbeit behandelt das Thema Strahlenschutz im Medizinbau und versucht, die verschiedenen Möglichkeiten des Strahlenschutzes zu erklären. Um die Anforderungen an den Strahlenschutz zu erfüllen, müssen die grundlegenden Begriffe und Mechanismen der Physik bekannt sein. So unterscheiden sich die zu setzenden Maßnahmen wesentlich nach der Art und Energie der Strahlung. Viele der Ziele die der Strahlenschutz erfüllen soll, gehen aus den gesetzlichen Bestimmungen hervor. In Österreich werden diese durch das Strahlenschutzgesetz und der Allgemeinen Strahlenschutzverordnung bzw. der Medizinischen Strahlenschutzverordnung geregelt. Die letzten großen Anpassungen des Gesetzes und der Verordnungen wurden mit dem EU-Beitritt notwendig und Anfang des neuen Jahrtausends umgesetzt.

Die Strahlenbelastung kann mithilfe von organisatorischen und technischen Maßnahmen verringert werden. Dabei reichen organisatorische Maßnahmen, wie das Begrenzen der Strahlungsintensität und der Aufenthaltsdauer, bei medizinischen Anwendungen meist nicht aus. Deshalb gibt es mit der Ö-Norm S5212 und der Ö-Norm S5224 zwei Regelwerke, die die Vorgehensweisen der Abschirmungen für Röntgenapparate und nuklearmedizinischen Anwendungen vorgeben. Die notwendige Abschirmung schwankt dabei je nach Anwendung stark. Blei hat zwar die besten strahlenschutztechnischen Eigenschaften, wird aber mit steigender Schichtstärke unwirtschaftlich. Um ein kostengünstige Abschirmung zu errichten, empfiehlt es sich, auf billigere Materialien (z.B: Beton) zurückzugreifen. Die dabei entstehenden, dickeren Schichtstärken können durch Zuschlagsstoffe oder Bleibeschichtungen verringert werden. Hingegen sind Eisenplatten, wegen ihrer hohen Herstellungspreise, für eine wirtschaftliche Abschirmung nicht geeignet.

Zusammenfassung (Englisch)

The topic of this thesis is the structural radiation protection in healthcare-buildings. The reason why this is a matter of interest, is the fact, that ionizing radiation can´t be recognized with our sensory organs. That means it´s a scentless, invisible and inaudible but a very harmful radiation. But if this form of radiation is used in the right hands, it´s an effective way to help people with particular health issues.

The first chapter is about a few bases that have to be known to realize an effective protection. One of the most important things to know is the kind of radiation. There are two groups: directly ionizing and indirectly ionizing radiation. The kind and energy of the radiation decides about the interaction of the radiation particles with the subject matter. The form of interaction is a significant indicator about the danger and the need of a radiation-shielding. It is relatively easy to shield direct ionizing particles, like the alpha or beta particles, because of their characteristics. On the other hand it can be very difficult to shield indirect ionizing radiation. This group of radiation contains emissions like the gamma radiation and x-rays. Because of their pervasive attributes, gamma radiation and x-rays are the most common used forms of radiation in medicine. They are used for a lot of different applications in diagnosis and therapy of several diseases.

Like the most important issues of life, the radiation protection is regulated by many different laws. The three main laws in Austria have the task to protect the population as well as employees, who have to work with radiation. Most of the laws in the world are based on the recommendations of the ICRP. This organization was founded in 1928 and has been engaged with the questions of radiation protection since then. The last major adjustments of the Austrian laws were made in the years 2002 and 2004. This was necessary as a result of the accession to the European Union.

There are a few ways to avoid a heavy dose of radiation. On the organizational level it is possible to reduce the exposure with a few methods. The first important way is to reduce the energy of the radiation source. This means, that the energy should be reduced to a minimum, depending on the type of use. Another part of the organizational opportunities is the reduction of time in which the employees are exposed to the radiation.

The main part of this thesis considers the constructive part of the radiation protection. A lot of construction rules are given by laws and standards. Another important rule can be found from physical laws: the inverse-square law. According to this rule, the dose of radiation decreases with a higher distance. Nevertheless a shielding is necessary in the most cases, because of the high radiation energies in medicine. Therefore complex calculations are required. In this thesis two variants of calculations are described. Gamma radiation is calculated according to Ö-Norm S5224 and the computations of x-rays are made according to Ö-Norm S5212. After the ascertainment of the required thickness of different materials and their pricewise valuation, some statements can be made. Lead is the best material for a radiation-shielding. Particularly as a shielding-material against x-rays it is a space saving and economic material. But if the thickness increases, it gets too expensive. Opposed to lead, common metal is not an economic material. The characteristic protection against radiation is not very good and the price is quite high. Because of the low price concrete is a cheap alternative. It is possible to use normal concrete, or heavy concrete. In this variation of common concrete, heavy aggregates (baryte) are used to improve the protecting attributes. A combination of different materials can help to find a tolerable compromise between thickness, weight and costs.