The invention relates to a system for assisting a user in positioning a thermal ablation device (1) on the basis of a planned ablation position. The system comprises an evaluation unit (6) adapted to (i) compute an optimized thermal dose distribution deliverable to the treatment region by means of the device (1) operating at a current position thereof, (ii) determine a path for steering the device (1) from the current position to the planned position and to assign a cost to the determined path, the cost quantifying estimated detrimental effects of steering the device (1) along the computed path, the cost quantifying estimated detrimental effects of steering the device (1) along the computed path, and (iii) present information about the determined thermal dose distribution and/or about the cost assigned to the computed path to the user.
