Advisory DI21/03: Requirements for comparison with national diagnostic reference levels

Advisory details

Purpose

To clarify the requirements for conducting comparisons of radiation dose levels and administered activity for imaging procedures against the Australian national diagnostic reference levels (DRLs) for:

• Multi detector computed tomography (MDCT) for adult and paediatric patients
• General nuclear medicine and Positron Emission Tomography (PET) for adult patients
• Computed tomography (CT) as part of positron emission tomography (PET) and single photon emission computed tomography (SPECT) for adult patients
• Diagnostic coronary angiography.

Issue

Diagnostic Imaging Accreditation Scheme Standard 3.2, Optimised Radiation Technique Charts requires a diagnostic imaging practice, which uses ionising radiation, to establish a program to ensure that median radiation doses and administered activity are:

• annually compared with DRLs for diagnostic imaging procedures for which national DRLs have been established in Australia; and
• where DRLs are consistently exceeded, imaging protocols are reviewed to determine whether optimisation is required.

DRLs provide benchmarks against which diagnostic imaging practices can compare their median radiation doses, also called a facility reference level (FRL), and administered activity for common imaging procedures.

The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has published national DRLs for computed tomography for adult and paediatric patients, general nuclear medicine, PET, and diagnostic coronary angiography for adult patients.

ARPANSA released the first national DRLs in July 2012 and regularly introduces new and revised national DRLs.

This Advisory applies to diagnostic imaging practices providing:

• MDCT for adult and paediatric patients
• Nuclear medicine for adult patients including:
  • General nuclear medicine
  • PET
  • CT conducted as part of PET and SPECT procedures for the purposes of attenuation correction or localisation
• Diagnostic coronary angiography procedures^[1]

Requirements

Procedures with national DRLs

Diagnostic imaging practices using ionising radiation are required to:

• Be aware of the latest relevant national DRLs (See ARPANSA website)
• Have a program to collect radiation dose data, calculate FRLs and compare these to the established national DRLs.
• Undertake an annual audit to review the comparison results and where the FRL exceeds the national DRL, investigate whether the imaging protocol can be optimised
• Maintain audit records which show the FRL calculation and comparison, the review process and any investigation, and submit these at each accreditation assessment.
• Provide in the audit records a justification when the median radiation dose (the FRL) is higher than the national DRL
• Update practice policies within six months of new or revised national DRLs being published by ARPANSA.

Nuclear medicine and PET procedures with a fixed administered activity

Where the administered activity for a nuclear medicine or PET procedure is fixed in an imaging protocol, requirements for the procedures with national DRLs (see above) are applied with the exception that the:

• Program to collect radiation dose data is not required
• Annual audit compares the administered activity in the protocol to the national DRL
• Audit records do not need to reference the FRL calculation
• National DRL for each procedure is documented in the imaging protocol

Nuclear medicine and PET procedures using weight corrected administered activity

Where a nuclear medicine or PET procedure uses a weight corrected administered activity, the requirements for the procedures with national DRLs (see above) are applied.

Computed tomography component of nuclear medicine hybrid imaging^[2]

The national DRLs published for CT in conjunction with SPECT or PET apply to procedures conducted for the purposes of attenuation correction or localisation. The requirements for procedures with national DRLs (see above) are also applied to these procedures.

Accrediting Agencies

For the DIAS, accrediting agencies are required to review evidence of data collection, determination of FRL, audit processes, audits and investigations of improvements to confirm a diagnostic imaging practice is using the latest national DRLs in its:

• policies for undertaking a DRL comparison
• data collection tools and records

For more information

Information on DRLs is available on the ARPANSA website. Enquiries relating to the calculation of DRLs and the operation of the National Diagnostic Reference Level Service should be directed to ARPANSA by calling 1800 033 972 or by emailing ndrld@arpansa.gov.au

For guidance on evidentiary requirements for Standard 3.2, see the DIAS User Guide for Practices Applying for Accreditation.

• ^[1] Angiography procedures listed in Subgroup I3 of the Diagnostic Imaging Services Table require accreditation with the DIAS for Medicare benefits to be payable.
• ^[2] Where the CT component of a nuclear medicine scanner is used to perform diagnostic imaging then compare the CT dose to the MDCT DRL where there is a comparable scan category.