The present invention refers to a system for medical treatment comprising a medical device and a separate hand-held device. The medical device comprises an energy-receiving unit and the separate hand-held device comprises a housing and an energy-transfer unit to transfer energy to be used at least in part for performing medical treatment to the energy-receiving unit of the medical device when the energy-receiving unit and the energy-receiving unit are in an energy-transfer position. The system further comprises at least one position sensor adapted to detect at least when the energy-transfer unit and the energy-receiving unit are in the energy-transfer position. The system further comprises a controller for controlling the energy-transfer unit such that the transfer of energy needed for medical treatment from the energy-transfer unit to the energy-receiving unit is enabled only when the energy-transfer unit and the energy-receiving unit are in the energy-transfer position.