Yes, it is called a "simulation" (at least here in Ontario), and it involves lying on the actual table to take readings and apply small tattooed dots for alignment. For the radiation to my spinal lesion, they also made what I called a "Hannibal Lecter mask" ( face cage) custom molded to hold my head back in an awkward position and my upper and middle spine still — be grateful you don't have to deal with that for radiation to the prostate (!!!)

After the simulation, the cancer centre's physicist designs your treatment plan and programmes it into the computer. It took about a week for me between each of my similations and the start of actual radiation therapy (SBRT), but I don't know what the maximum allowed time would be.

Best of luck!