The calibration of targeting for an ultrasound-guided high-intensity focused ultrasound system

Accurate targeting is essential to ensure safety for high-intensity focused ultrasound (HIFU) treatment. Recently we developed an ultrasonography-guided high-intensity focused ultrasound (USgHIFU) system, in which the imaging probe is mounted into the central hole of spherical HIFU phased-array transducer for targeting and monitoring. An acrylic plate with two flat-head bolts is used for the assessment of the targeting accuracy. Imaging planes with the angles from -90° to 90° with an interval of 30° were calibrated and respective targeting errors were measured. And the targeting errors of non-calibrated imaging planes were derived from the average of the nearest two calibrated planes. The coordinates in HIFU sonication were corrected by the error in the specific imaging plane. With the proposed calibration approach, the targeting error has been reduced to less than 0.5 mm. In vitro experimental result also shows that the temperature rise of the targeting focus in the image is similar to the result of previous work. In conclusion, our USgHIFU system is capable of accurate sonication.