Apparatus and method for ultrasound catheter calibration

A method for calibrating an ultrasound probe having a beam plane, the method including: directing the probe to receive reflected ultrasonic waves a white including a plurality of linear elements crossing at a crossing point and arranged for intersect the beam plane at respective intersection points; receive signals from the probe in response to the reflected ultrasonic waves; and aligning the probe by modifying at least one of a position and an orientation of the probe responsively to the signals so that the intersection points are at a desired location in the beam plane where the alignment of the probe comprises: forming using the signals, an ultrasound image in which the intersection points of the linear elements appear as dots; and modifying at least one of the position and orientation of the probe in response to the points that appear in the image; where at least one change of position and orientation of the probe includes modifying the orientation of the probe responsively to a distance between points in the image; and where realigning includes rotating the probe so that the dots converge to a single point corresponding to the crossing point.