When a magnetron is scanned about the back of a target in a selected complex path having radial components, the erosion profile has a form depending upon the selection of paths. A radial erosion rate profile for a given magnetron is measured. Periodically during scanning, an erosion profile is calculated from the measured erosion rate profile, the time the magnetron spends at different radii, and the target power. The calculated erosion profile may be used to indicate when erosion has become excessive at any location prompting target replacement or to adjust the height of the magnetron above the target for repeated scans. In another aspect of the invention, the magnetron height is dynamically adjusted during a scan to compensate for erosion. The compensation may be based on the calculated erosion profile or on feedback control of the present value of the target voltage for a constant-power target supply.