My mum is the manager at Qld Xray up here, so I'll give her a call today and find out for you. All they've got on their website is this:
Restrictions apply for pregnant and breast feeding patients. Please contact practice for details.
I'll get back to you later with more info.

ETA:
Also found this:
How long does the radiotracer stay in your body?
Generally, most radiotracers are undetectable within 24 to 36 hours.
In some procedures, however, the radiotracer may last up to 7 - 14 days. The radiation dose is minimal and is often much less than ordinary x-ray studies. Once the procedure is completed there are no precautions to take and you can continue everything as normal.