REIRRADIATION

BRAIN REIRRADIATION

  • assume alpha-beta of 2
  • BED is calculated normally
  • NTD = BED/2.
  • Radiation-induced normal brain tissue necrosis is found to occur at NTDcumulative >100 Gy.[3]

SPINAL CORD REIRRADIATION

  • spinal reirradiation appeared to be effective and safe when the cumulative BED is </=120 Gy.
  • Radiation myelopathy appears small after <135.5 Gy2 when the interval is not shorter than 6 months and the dose of each course is <98 Gy2.[1]
  • Two spinal cord retreatment experiments revealed a similar fractionation sensitivity for radiotherapy (RT) of reirradiated and previously untreated rats. Therefore, we chose an alpha-beta value of 2 Gy for the cervical and thoracic cord and 4 Gy for the lumbar cord.[2]
  • To be conservative alpha-beta of 2 will be used for calculations.

Biological Effective Dose (BED) for alpha-beta of 2

bed2
Bibliography
1. Carsten Nieder, Anca L. Grosu, Nicolaus H. Andratschke, Michael Molls. Update of human spinal cord reirradiation tolerance based on additional data from 38 patients , International Journal of Radiation Oncology * Biology * Physics 1 December 2006 (Vol. 66, Issue 5, Pages 1446-1449)
2. Carsten Nieder, Anca L. Grosu, Nicolaus H. Andratschke, Michael Molls. Proposal of human spinal cord reirradiation dose based on collection of data from 40 patients International Journal of Radiation Oncology * Biology * Physics. 1 March 2005 (Vol. 61, Issue 3, Pages 851-855)
3. Ramona Mayer, Peter Sminia. Reirradiation Tolerance of the Human Brain. International Journal of Radiation Oncology * Biology * Physics 1 April 2008 (Vol. 70, Issue 5, Pages 1350-1360).
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