A medical apparatus (600, 700, 800) including a high intensity focused ultrasound system (602), a signaling device (628) for generating a discomfort signal during the sonication of the sonication volume, and a processor (634) for executing instructions. Execution of the instructions causes the processor to receive (102) a set of sonication points (658, 904). At least one of the set of sonication points is identified as a test location (908, 912). The instructions further cause the processor to perform for each sonication point: determine (106) if it is a test location； perform (108) a test sonication (204, 304, 404, 504) if it is a test location； repeatedly test (110) for the discomfort signal during the test sonication； sonicate (114) the sonication point if it is not a test location or if the discomfort signal was not detected； and abort (112) the sonication if the discomfort signal was detected.
