Few options:
(1) Transfer to radiography. You could get into the Monash or RMIT course. Keep in mind the ATAR requirement is very high. If you previously couldn't make it in, that may (unfortunately) be the case now. Since you are a second year, they will also consider your uni marks to a much higher degree. You may get a unit or two off as credit (dubious) but most likely you'll start from scratch with all the other first years.
(2) Finish your science degree. Get a masters in diagnostic radiography, etc. I am unaware if any of these are offered in Victoria at the present time, i don't think they are. They are available interstate though.
The masters may cost more but it will be shorter and somewhat less mind numbing than starting from scratch. You will also end up with two degrees (although of dubious benefit if you will work as a radiographer).
Also consider similar fields like radiation medicine/therapy (used for breast cancer and a few other kinds) and medical physics. These positions are only in large hospitals though. This compares to radiography where there are many radiography places dotted through the suburbs. So, the number of jobs is far larger for radiography (reflected in entrance standards too).