The present disclosure provides a method for determining an ultrasound focus location in a thermal image. In one aspect, the method includes obtaining a magnetic resonance thermal image of a tissue heated by a focused ultrasound and correcting a chemical shift and a k-space shift of a monitored ultrasound focus location in the magnetic resonance thermal image such that the monitored ultrasound focus location is aligned with a real physical ultrasound focus location. Correcting the chemical shift includes correcting a first spatial error of the monitored ultrasound focus location caused by resonance frequency changes of hydrogen nuclei due to environmental differences of water molecules. Correcting the k-space shift includes correcting a second spatial error of the monitored ultrasound focus location caused by temperature error due to spatial variations of a primary magnetic field.
