Hi @Alexander_S welcome to the PyMedPhys Discourse

I’m still on leave so likely to not be that responsive, but nevertheless I can answer a little here.

Could you give some context to that statement? What other things are they also saying about their gamma calculation?

There’s a neat property of the gamma function that given a distance threshold of `d`

, for a given radius `x`

any distance larger than that radius `x`

cannot have a gamma value smaller than `x/d`

. Therefore, if you search for gamma in progressively larger sphere surfaces you can disregard points if a gamma value found is smaller than the current search radius / distance threshold.

By default PyMedPhys’ gamma algorithm defaults to prioritising accuracy over speed. You can however limit the gamma to a maximum value which will stop it searching at a given radius, you can also make it only calculate a random subset of points which will approximate a similar pass rate, one can also make the points stop searching if any point is found to pass which means individual gamma values may be higher that what could be possibly found be found, but if only a pass rate is desired this is sufficient.

If you can provide the reference where your original quote is from hopefully I can help further.

Cheers,

Simon