Online Temperature Control of Focused Ultrasound Heating using an Adaptive PID Feedback Loop

Silke Hey¹, Mario Ries¹, Chrit Moonen¹

The combination of real time MR thermometry with a proportional, integral, derivative (PID) feedback control has been suggested as a precise solution for controlling high intensity focused ultrasound devices in applications such as local drug delivery. However, depending on the desired target temperature profile and the measurement noise, overshoots and oscillations can occur, which lead to undesired tissue damage. Here an adaptive PID controller algorithm is presented that continuously adjusts the controller gains as a function of the current temperature error and the measurement noise. Its superior performance in comparison to a conventional PID controller with static controller gains is demonstrated experimentally.