LET Monitoring Using Liquid Ionization Chambers
| Autor: | Andrea Mairani, Katia Parodi, Michael H. Holzscheiter, Stephen D. Bello, Sara Tegami, Shuang Luan |
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| Rok vydání: | 2017 |
| Předmět: |
High-LET Radiation
Physics Physics::Medical Physics Linear energy transfer Radiation 030218 nuclear medicine & medical imaging Computational physics 03 medical and health sciences 0302 clinical medicine Nuclear magnetic resonance 030220 oncology & carcinogenesis Ionization Relative biological effectiveness Particle beam Beam (structure) Physical quantity |
| Zdroj: | International Journal of Medical Physics, Clinical Engineering and Radiation Oncology. :197-207 |
| ISSN: | 2168-5444 2168-5436 |
| DOI: | 10.4236/ijmpcero.2017.62018 |
| Popis: | Relative biological effectiveness (RBE) is an important quantity in planning particle beam cancer therapy. In general, the RBE describes the biological effectiveness of a given primary beam with respect to a reference photon irradiation. RBE varies not only for different primary beams but also with depth in the target for a given beam modality. It is not a quantity that easily lends itself to measurements or computation as it depends on many biological and physical quantities. Numerous experiments in vitro using various cell lines and irradiation modalities have shown that a general relationship between RBE and the physical quantity Linear Energy Transfer (LET) exists. Several groups have proposed including LET in the radiation therapy treatment planning instead of the more complicated and elusive RBE. It has been shown that LET is an important quantity to consider in treating radio-resistant tumors. The concept of LET painting has been proposed with the goal of improving tumor control probability (TCP) for hypoxic tumors by focusing high LET radiation on the hypoxic region of the tumor while restricting the surrounding normal tissue to low LET radiation. In order to properly incorporate LET in clinical treatment, it is important to be able to experimentally measure and verify LET distribution. We propose a novel method for measuring LET using a dual chamber methodology exploiting the difference in the observed recombination between air filled ionization chambers (IC) and liquid filled ionization chambers (LIC). The resulting difference in the measured signals will be used to directly extract the relative LET of an actual treatment beam in real time. This paper describes our initial studies of this method, presents preliminary results, and discusses further improvements toward a practical real-time LET measuring device. |
| Databáze: | OpenAIRE |
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