Hi Toontoon
Quote from Immigration website:
http://www.immi.gov.au/migrants/family/parent/143/index.htm"What does this visa let me do?
This visa allows you, your accompanying spouse and dependent family members to live as permanent residents in Australia.
You can also:
work and study in Australia
receive subsidised healthcare through Medicare and the Pharmaceutical Benefits Scheme (PBS)
access certain social security payments (subject to waiting periods)
be eligible to apply for Australian citizenship (subject to the residency eligibility criteria)
sponsor people for permanent residence (subject to waiting periods)."
In answer to your question above, and in light of the fact that they will be covered by Medicare, then if they went to a 'bulk billing' surgery such as Marion Domain they could see the doc and have the X-ray done (in the same building) for free. Not all doctors 'bulk bill' and there may be extra charges to pay in those instances, known as 'the gap'.
Basically the govt pays a standard fee for various doc's services, but docs may choose to charge more, in which case you have to pay the difference.