The invention relates to a medical
system (15) comprising a medical instrument (16), preferably an electromedical instrument (17) or electrosurgical instrument (18). At least one
magnetic field sensor (30), which is preferably in the form of a
quantum magnetometer or an NVCD sensor, is provided on a tool part (19) of the instrument. Each
magnetic field sensor (30) is designed to detect a
magnetic field (38) emanating from the electromedical instrument (17) and / or from a
biological tissue (20) and to provide a corresponding sensor
signal (S), preferably an optical sensor
signal (Sopt), which can be evaluated by means of an evaluation device (35). The evaluation device (35) determines at least one operating parameter (EP). The at least one operating parameter (EP) describes the
biological tissue (20) and / or the effect generated by the medical instrument (16) or the tool part (19) on the
biological tissue (20). For example, an operating parameter (EP) can describe the
tissue type, a temporal and / or local change in the tissue, or the current temperature (T) or a local and / or
temporal change in the temperature (T) of the biological tissue (20). Such operating parameters (EP) can be monitored very dynamically by measuring the magnetic field.