Proton therapy is an increasingly popular form of radiotherapy that uses high energy protons for the treatment of cancer. It results in a lower integral dose than the classical photon radiotherapy. This makes it suitable for the treatment of tumors close to critical organs such as in the head and neck. To minimize alignment errors the head and neck are immobilized during treatment. Current immobilization methods are uncomfortable and unable to correct local misalignments between the head and the body. Therefore, an adaptive immobilization device is designed that can correct the local misalignments of the head and neck.