Thank you for this! Bringing me back to the basics. Answer, no can't prove medical necessity as it is only because the patient doesn't meet CMS payer eligibility requirements. There is nothing coding wise that requires the payer elements. Authorization depends on the payer but more than likely yes. What sparked the question is the US preventative task force changed the pack years to over 20 instead of over 30. My centers took it upon themselves to make the changes to over 20 which left me without documentation of over 30 packs. CMS and payers have not updated their requirements. Thank you again.I am wondering why the screening CT was ordered if the patient didn't qualify. Can you prove medical necessity if you end up coding as a diagnostic? Does the patient's insurance require precertification for a CT?