The generation of a pattern and for an adaptation to the specific geometry requires a lot of manual work. The workflow for the clinician is simplified during treatment planning. A treatment planning system is configured for determining a set of catheter or needle insertion positions to be used during treatment. The treatment planning system includes an image providing module for providing a medical image from which at least one treatment target structure can be derived. Further the treatment planning system includes a pattern providing module for providing one or a set of standard patterns for catheter or needle insertion including a plurality of catheter or needle insertion positions. The catheter or needle positions relate to treatment positions in the at least one treatment target structure.