They mean slightly different things. In this instance, introduction means something that introduces, or is a preliminary, to something else.
: something that introduces: such as
a(1) : a part of a book or treatise preliminary to the main portion
(2) : a preliminary treatise or course of study
If it were "introduction to," instead of "introduction on," the emphasis would not be on what the introduction is about, but what it is supposed to do: help you understand, in this case, deep learning methods in Mammography.
According to Ngram, "introduction to" is vastly more common, but without more context, I can't say which I think is more appropriate.