Alpha/beta ratio for arteriovenous malformations estimated from obliteration rates after fractionated and single-dose irradiation.

Autor: Kocher M; Department of Radiation Oncology, University of Cologne, Cologne, Germany., Wilms M, Makoski HB, Hassler W, Maarouf M, Treuer H, Voges J, Sturm V, Müller RP
Jazyk: angličtina
Zdroj: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology [Radiother Oncol] 2004 Apr; Vol. 71 (1), pp. 109-14.
DOI: 10.1016/j.radonc.2003.08.005
Abstrakt: Background and Purpose: Results from single-dose radiosurgery have failed to yield reasonable alpha/beta 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 = (alpha/E) + (beta/E)d, and alpha/beta-ratios were calculated from the parameters of the regression line.
Results: Fractionated radiotherapy with 20 Gy/4 Gy fractions, 50 Gy/2 Gy fractions and single-dose radiosurgery of approximately 13 Gy were isoeffective with crude obliteration rates of 13%. The analysis yielded an alpha/beta-ratio of 3.5 Gy. For small-sized AVMs (<3 cm), alpha/beta-ratios of 4.6-6.4 Gy 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: MEDLINE
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