Can diagnostic imaging for a public hospital outpatient be bulk billed if there is a named referral and patient consent, but the registrar completes the imaging request form – and is it true that the request does not have to be signed?

Can a request for diagnostic imaging in a public hospital be Medicare billed if:

1) appropriate GP referral to a named obstetrician has occurred

2) the patient has elected to be a no fee private patient for attendance in the antenatal clinic

3) request for ultrasound imaging is filled out by a registrar "on behalf of" a specialist with ROPP named on the request while attending the antenatal clinic

4) patient consents to be bulk billed for the scan

Also, the NSW guideline states a request for imaging does not require a signature to be valid. Is that correct?