Exemplary axial slide of a representative plan using stereotactic body radiotherapy (SBRT) for the experimental arm. This example demonstrates how overlapping parts between the planning target volume (PTV) and planning organ at risk volume (PRV) are removed to define the final PTV. There is a steep dose gradient to spare the urethra while preserving a sufficient dose to the PTV. Relevant organ as risks, PTVs and isodoses in colorwash are illustrated according to the legend.