α/β Ratio for arteriovenous malformations estimated from obliteration rates after fractionated and single-dose irradiation

Autor: Marc Wilms, Jürgen Voges, Werner Hassler, Volker Sturm, Mohammad Maarouf, Martin Kocher, Rolf-Peter Müller, Hans-Bruno Makoski, Harald Treuer
Rok vydání: 2004
Předmět:
Zdroj: Radiotherapy and Oncology. 71:109-114
ISSN: 0167-8140
Popis: Background and purpose Results from single-dose radiosurgery have failed to yield reasonable α / β ratios for obliteration rates of arteriovenous malformations (AVMs) in the framework of the linear-quadratic approach. We used outcome data from single-dose and fractionated radiotherapy for AVM to approach this problem. Patients and methods AVM obliteration rates observed in an updated historical series of fractionated radiotherapy and from six recent series of single-dose stereotactic radiosurgery were analyzed. Reciprocal total doses (1/ D ) and fraction sizes ( d ) of isoeffective fractionation schemes were entered into the rearranged form of the linear-quadratic equation: 1/ D =( α / E )+( β / E ) d , and α / β -ratios were calculated from the parameters of the regression line. Results Fractionated radiotherapy with 20Gy/4Gy fractions, 50Gy/2Gy fractions and single-dose radiosurgery of ∼13Gy were isoeffective with crude obliteration rates of 13%. The analysis yielded an α / β -ratio of 3.5Gy. For small-sized AVMs ( α / β -ratios of 4.6–6.4Gy were obtained. Conclusion These results support the view that radiosurgery for AVM can be understood as a typical late tissue effect with a high fractionation sensitivity. Fractionated radiotherapy is ineffective for AVMs and should be evaluated carefully in other benign targets.
Databáze: OpenAIRE
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