A medical apparatus (600, 700, 800), comprising: - a high intensity focused ultrasound system configured to generate focused ultrasonic energy for sonicating a treatment volume of a subject; - a signaling device configured to enable the subject to generate a discomfort signal during the sonication of the sonication volume; - a memory containing machine executable instructions (660, 662, 664, 666, 706, 822) for controlling the medical apparatus; - a processor for execution of the instructions, wherein the processor is configured to receive a set of sonication points (658, 904) containing coordinates of locations within the treatment volume, wherein at least one of the set of sonication points is identified as a test location (908, 912); wherein the processor is configured to control the medical apparatus to perform the following for each sonication point of the set of sonication points: - determine if the sonication point is the test location; - perform a test sonication (204, 304, 404, 504) of the sonication point using the high intensity focused ultrasound system if the sonication point is the test location; - test repeatedly for the discomfort signal from the signaling device during the test sonication; - sonicate the sonication point if the sonication point is not a test location or if the discomfort signal was not detected; and - abort the sonication if the discomfort signal was detected. - a high intensity focused ultrasound system configured to generate focused ultrasonic energy for sonicating a treatment volume of a subject; - a signaling device configured to enable the subject to generate a discomfort signal during the sonication of the sonication volume; - a memory containing machine executable instructions (660, 662, 664, 666, 706, 822) for controlling the medical apparatus; - a processor for execution of the instructions, wherein the processor is configured to receive a set of sonication points (658, 904) containing coordinates of locations within the treatment volume, wherein at least one of the set of sonication points is identified as a test location (908, 912); wherein the processor is configured to control the medical apparatus to perform the following for each sonication point of the set of sonication points: - determine if the sonication point is the test location; - perform a test sonication (204, 304, 404, 504) of the sonication point using the high intensity focused ultrasound system if the sonication point is the test location; - test repeatedly for the discomfort signal from the signaling device during the test sonication; - sonicate the sonication point if the sonication point is not a test location or if the discomfort signal was not detected; and - abort the sonication if the discomfort signal was detected. - determine if the sonication point is the test location; - perform a test sonication (204, 304, 404, 504) of the sonication point using the high intensity focused ultrasound system if the sonication point is the test location; - test repeatedly for the discomfort signal from the signaling device during the test sonication; - sonicate the sonication point if the sonication point is not a test location or if the discomfort signal was not detected; and - abort the sonication if the discomfort signal was detected.