Motion compensation for non-invasive treatment therapies

A method of monitoring movement of a volume of tissue during treatment thereof, the method comprising the steps of:

• obtaining a model of anticipated movement of a target volume;
• tracking the target volume during treatment thereof using two tracking modalities, wherein the first tracking modality provides initial estimated target volume locations at a first information update rate, and the second tracking modality identifies subsequent estimated target locations of the target volume based on images obtained at a second information update rate lower than the first information update rate wherein the subsequent estimated target locations are more accurate than the initial estimated target volume locations;
• comparing the initial estimated target locations to the model to determine a tracking error;
• if the tracking error exceeds a safety threshold, suspending treatment;
• and
• adjusting one or more treatment parameters based on the subsequent estimated target locations of the target volume.