Real time contact-free and non-invasive tracking of the human skulltextemdash first light and initial validation

In an increasing number of fields in medicine, precise and fast localisation of targets inside the body is essential. We present a new technology to directly track the position of the human skull through tissue in real time using infrared lasers. To achieve this, an experimental optical setup has been developed to target a position on a subject’s skin and compute the soft tissue thickness using analysis of the scattering pattern. Using this setup and validation data from high-resolution MRI and optically tracked force-controlled ultrasound, we succeeded in computing the soft tissue thickness on the subjects’ foreheads with sub-millimetre accuracy.