A probehead for an electron spin resonance (ESR) dosimeter comprises a resonator and an insert extending into the resonator. The insert has a guide channel for bringing a sample into the resonator. The sample comprises a dosimeter substance. The guide channel is configured for receiving and guiding a test strip. The insert is provided with a first machine-readable code imprint. The insert is provided with at least one reference sample. A pressurized air unit is provided for blowing the sample out of the resonator after completion of a measurement. The insert has an opening on an upper side of the resonator. The opening is openly accessible for manually inserting dosimeter pills thereinto. The insert, further, is provided on the upper side with a pressurized air connector. The pressurized air connector is connected to an orifice via a pressurized air channel within the insert. The orifice is located within a lower, otherwise closed bottom of the guide channel. The sample substance comprises a chromium-doped magnesium oxide (Cr:MgO). The magnesium oxide is doped with the isotope 52Cr.