A new PTB measuring system offers the possibility of measuring the absorbed dose in the direct environment of the irradiated tumour.
During radiation therapy, the physicians try to keep the dose in the tumour as high as possible to destroy as many cancer cells as possible. To avoid the damaging of healthy tissue, it is becoming more and more important to check the exact amount of the dose.
For this purpose, the Physikalisch-Technische Bundesanstalt (PTB) has developed a measuring system in the case of which the amino acid "alanine", whose radiation transport properties resemble those of human tissue, is used as indicator.
When alanine is irradiated, free radicals are formed, whose concentration is measured with the aid of electron spin resonance (ESR). This allows the absorbed dose to be derived.
First investigations on a phantom – and also on patients - have shown that the method is well functioning.
- Anton et al. In vivo dosimetry in the urethra using alanine/ESR during 192Ir HDR brachytherapy of prostate cancer - a phantom study. Physics in Medicine and Biology, 2009; 54 (9): 2915 DOI: 10.1088/0031-9155/54/9/022
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