In radiation therapy, accurate knowledge of the localization and shape of a tumor is essential in order to destroy it while sparing healthy surrounding tissue. As a number of organs are subject to respiratory motion, tumors located in these areas move too. Therefore, some equipment is needed in order to either directly monitor the position of the tumor during beam delivery or indirectly localize the tumor by correlating tumor motion with that of a respiratory marker. When applied to the chest or abdominal wall, the magnetic distance sensor described above constitutes such a respiratory marker and assists clinicians in studying and monitoring patient respiration during radiotherapy
Gait analysis is another domain where the magnetic distance sensor can be useful. For example, it was demonstrated that by taping the sensor on the leg, each element at equal distance of the knee joint, one obtains a distance signal which evolves in perfect agreement with the knee angle signal extracted from video data. This opens up the possibility of recording gait over long periods of time, on long distances, and in environments where introducing a video acquisition system is impracticable.
In applied physiology, the use of the magnetic distance sensor as a tool to estimate ventilation and energy expenditure has also been investigated. In this application, two pairs of electromagnetic coils allow to measure rib cage, abdominal and chest wall distances.
From these measurements, it is possible to accurately estimate ventilation and energy expenditure , in sitting, standing, and moderate exercise conditions. This research sets up the basis for further investigation of the applicability of the technique to daily life conditions and vigorous physical activity.