When re-irradiating the spinal cord, what do you use as a guideline for the interval between treatment and the amount of tolerance theoretically "regained"?
I'm aware of a number of publications that suggest that after 1-2 years, the cord should be able to handle about 50% of the original tolerance dose. In training at the University of Kentucky, now several years ago, we were given a rule of thumb that suggested one should regain about 10% of the original cord tolerance for every year that has passed from the prior XRT series. I don't really know of any references to back that idea up, but I'd be glad to hear whether or not anyone else uses such a "rule of thumb."
Answer from: Radiation Oncologist at Academic Institution
Perhaps the most commonly used estimate is that the spinal cord “heals” 25% of the previously delivered dose six months after completing radiation. While this statement didn’t originate with the QUANTEC paper by Kirkpatrick et al. on the subject, it is explicitly stated there, and ...
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Answer from: Radiation Oncologist at Community Practice
Data appear to be limited. You might consider the paper published by Nieder, et al., where in 'the risk of radiation myelopathy appears small after < or =135.5 Gy(2) when the interval is not shorter than 6 months and the dose of each course is < or =98 Gy(2)' They used an alpha-beta ratio of ...
Answer from: Radiation Oncologist at Academic Institution
I would suggest 6 months—see Dr. Kirkpatrick’s paper in the Quantec red journal issue