Theorie der Kleinwinkel-Vielfachstreuung geladener Teilchen unter Berücksichtigung geometrischer Grenzflächen* *Prof. Dr. Wolfgang Pohlit zum 70. Geburtstag gewidmet
| Autor: | Dietrich Harder, M.A. Mandour |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Physics
Range (particle radiation) Radiological and Ultrasound Technology Lateral surface Scattering Biophysics Boundary (topology) Collimator Electron Charged particle 030218 nuclear medicine & medical imaging law.invention Computational physics 03 medical and health sciences 0302 clinical medicine law 030220 oncology & carcinogenesis Ionization Radiology Nuclear Medicine and imaging Atomic physics |
| Zdroj: | Zeitschrift für Medizinische Physik. 8:134-142 |
| ISSN: | 0939-3889 |
| DOI: | 10.1016/s0939-3889(15)70315-6 |
| Popis: | Applying the small-angle multiple scattering theory of Rossi and Greisen, especially the pencil-beam solution supplied by E. Fermi, we have solved two boundary surface problems of multiple scattering of electrons and other charged particles in the energy range of radiation therapy. In the validity range of the small-angle approximation, the number and the angular distribution of the scattered electrons leaving the lateral surface of an electron-irradiated absorber block have been correctly calculated. The essential step has been to find a continuous solution describing the transition from inner to outer space of the absorber. Furthermore, the phenomenon of „quasi-reflexion”, occuring when electrons are entering a boundary plane under a small entrance angle, has been correctly reproduced as an analytical result. The correctness of the analytical results was checked by comparison with a highly accurate, own Monte-Carlo program. We are planning to extend the theoretical treatment by considering large-angle scattering as well. In the framework of radiation therapy with electrons and hadrons, the present results can be applied to understand and quantitatively estimate the effects of „in-scattering” into air-filled cavities of the irradiated body or of ionization chambers, of scattering at collimator edges and of „quasi-reflexion” in the case of small-angle incidence into applicator cone walls. |
| Databáze: | OpenAIRE |
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