Core Biopsy: "Meet the needles"

[@eueuio7621]

So, I understand with semiautomatic system, if you use ultrasound you can see for how long you penetrate with the needle, because when you fire the needle just retracts. With automatic system, you have to stimate the 15-20mm the needle is going to penetrate far away your position. Is that correct?
Thank you very much for your explanations

[@hmaria888]

Very clearly explained. Thank you.