"1. What is the meaning of chronic vs. transient toxicity?"
Chronic means ongoing side effects; transient means the side effect shows up but then fades away.
"2.Quoted from article "At the top treatment centers, radiation oncologists routinely deliver doses as high as 70 Gy, but seldom higher." 2. So what would be the logic in going up to 72? I'm assuming by the article that this is a safe dose but if even the top centers are doing 70 are we pushing it by doing the 72? Or does that go w/ what you were saying for each +1 GY survival goes up by 2 percentage points so why not if it's not going to have any more SE's."
Now you're getting it