The Calypso 4D Localization System is a medical device that guides radiation therapy delivery with sub-millimeter accuracy, reducing complications from organ motion during treatment. It uses electromagnetic fields to locate implanted miniature circuit transponders, smaller than a grain of rice, which continuously monitor tumor position during radiation therapy. Care was taken to avoid the conventional lab-equipment look prevalent in most radiation therapy rooms. The result is a non-threatening and approachable form that enhances the therapeutic environment for patients.