This study is investigating a new agent to be used in PET imaging for prostate cancer, called 68Ga-NTA-476. It aims to find out where 68Ga-NTA-476 goes in the body once it is injected into a person and whether there are any side effects or issues with tolerating the compound. This will be compared to an existing imaging compound which is currently used in Australia called 18F-DCFPyl. 68Ga-NTA-476 has been developed and tested in the laboratory; however, this is the first time that it will be tested in humans.