This paper presents a wireless tracking system capable of measuring position and orientation about three orthogonal axes with a frequency bandwidth of 320 Hz. A real-time algorithm determines the six degree-of-freedom (6DOF) sensor posture, comprising the three components of dimensional position (heave, sway and surge) and the three components of rotational orientation (pitch, yaw and roll). An inertial algorithm has been simulated in software and tested in hardware. Techniques for sensor functionality and 3D manipulation are described within this paper. A miniaturized version of this sensor is thought to be ideal in applications requiring detection or tracking of tumour motion in radiation oncology.