Diagnostic Reference Levels in Medical Imaging

Draft document: Diagnostic Reference Levels in Medical Imaging
Submitted by Sarah Allen , British Nuclear Medicine Society (BNMS)
Commenting on behalf of the organisation




ICRP Summary of Recommendations

BNMS comments



DRLs are not intended for individual patients

[12]This is in the one part of the introduction they state that For nuclear medicine the administered activity is weight based.

Within the UK this is not current practice and the BNMS has reservations on this, see 5.4. BNMS would prefer a sentence –weight based adjustments are suitable for some procedures. 



DRLs in planar and SPECT nuclear medicine imaging

[219]Weight based administered activity except where activity concentrates in a single organ

BNMS have reservations around introducing weight related adjustments for all procedures where the activity does not concentrate in a single organ, as evidence shows adjustments for MPIs showed were not straightforward as a pro-rata adjustment. Also, it is time consuming and more likely to increase errors. A move to weight based adjustments must ensure there are clear benefits to the patients from improved image quality and safety versus radiation dose. Weight based administered activity may only be of benefit in a proportion of nuclear medicine procedures (eg PET) beyond the single organ exceptions



Considerations for DRL surveys for nuclear medicine

[225] for some administered activities are highly dependent on the intended procedures ….it is difficult to compare administered activities without knowing the precise protocol used.

[226]DRL values in adult nuclear medicine are normally based on administered activity used for average sized patients (70+/-10Kg) and then a DRL value for the administered activity per unit body weight MBq per kg is calculated

Support statement that precise protocol for imaging must be know to compare DRLs (eg cardiac 1 or 2 day procedures)

BNMS would like to emphasize again that weight based alteration may not be appropriate. It is important this is stated



Hybrid imaging (PET/CT, SPECT/CT and PET/MRI)

[230]For Hybrid Imaging set each modality DRL separately

Supports this and assume this is current practice in the UK already



Hybrid imaging (PET)

[234]PET - set DRLS for each radiopharmaceutical , recommends that weight based injected activity and higher activity for obese patients but has set upper limit of 530MBq for 18FDG imaging on LYSO detectors so as not to affect image quality

Recommendations in line with current practice in the UK



Nuclear Medicine- Paed DRLs

[265-266] recommends for nuclear medicine simple scale administered activity by a factor linked to weight or size- states diagnostic quality must be preserved

This is current practice in UK (ARSAC/ EANM) support recommendation



Equipment performance in Nuclear medicine

[309]Recommends equipment maintenance if administered activity is routinely exceeded due to poor image quality at recommended DRL and that if maintenance does not improve image new equipment needed

Ties in poor image quality to old equipment – would hopefully be standard practice in UK – but good to have embedded in international guidance as this will support future good practice in UK