I recall someone was analyzing the refractive index of various tissues in order to tighten the target area for multi beam radiation therapy. Particularly for brain cancers. By hitting from multiple angles the dosage in surrounding tissues is lower, and by calculating how the head lenses the beam you reduce the high dose area in the middle, like a 3d Venn diagram.

But I don’t remember is whether that experiment became SOP or not.

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s0rce 5 hours ago | parent [-]

Won't the effective index of all materials be basically 1 for the high energy electrons involved here?

	▲	hinkley 5 hours ago \| parent [-]
		Seems not in this case. But I believe the use case was deep brain tumors, like the hippocampus, where any beam alignment problems could be life altering.