Sorry, ad-o: Using modern methodology, there is nothing to substantiate Helena's claims - and much to be rather sceptical about, since she had a political agenda in supporting her son in his role as Emperor. She may or may not have converted - that's God's business, not ours - but the situation in the empire needed stability. After all, at the time Helena was being an amateur digger, her son was building Churches, endowing Mithras cult Temples, issuing coins with both Christian and pagan symbolism on them - in other words, veing a typical Roman warrior/politician and hedging his bets. The hagiology and history are confused.