From the RSNA refresher courses - Freehand interventional sonography in the breast: Basic principles and clinical applications

The skills needed to perform ultrasonographic (US)-guided interventional procedures in the breast can be learned by practicing the key maneuvers on a tissue phantom. Use of a tissue phantom rather than a synthetic phantom provides the tactile feedback from transducer movement against tissue and from needle insertion into tissue, which more closely simulates the performance of the procedure in a real breast. There are three key transducer motions-sweeping, rocking, and rotating-that are used to achieve three important goals in US-guided procedures: finding the needle, maximally visualizing the needle, and correctly aligning the needle shaft and ultrasound beam. For each transducer maneuver, there is a corollary needle motion that can be used to achieve the same goal. Either the transducer or the needle should be moved during a procedure, not both simultaneously. Longitudinal alignment of the needle shaft with the ultrasound beam is best achieved with the perpendicular approach. The perpendicular approach is preferred because it allows superior needle visualization, orientation parallel to the chest wall, and location of the needle shaft at the focal zone. With use of a tissue phantom, the radiologist-in-training can practice the key procedures and tailor them to his or her individual preferences.