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What V5 dose constraint best correlates with late lung toxicity following definitive chemo-radiation for lung cancer?
Answer from: Radiation Oncologist at Academic Institution
In any radiation plan, improving conformity depends upon spreading the “low dose bath†or the V5. For years, there has been a lot of theoretical concern about spreading the low dose base and a number of retrospective analyses suggesting that the low dose bath migh...
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Answer from: Radiation Oncologist at Academic Institution
I agree with @Stephen G. Chun. We use V20 as the primary metric to develop the treatment plan, but its important to look at the entirety of the DVH curve when assessing the patients risk of pneumonitis. If I am comparing 2 plans with similar V20s, I will choose the plan that has a significantly lowe...
Answer from: Radiation Oncologist at Academic Institution
The reported mean V5 in both the 3D-CRT and IMRT arms in RTOG 0617 was below the commonly used constraint of 60-65%. It makes me wonder if the reason V5 did not correlate with toxicity is because the investigators stayed below a dose associated with pneumonitis. Would love @Jeffrey D. Bradley's inpu...
Answer from: Radiation Oncologist at Academic Institution
Thank you for your question. V5<=60% is an appropriate constraint and one that we use at MD Anderson.