An apparatus and method for triaging patients according to radiation exposure operates by measuring electron paramagnetic resonance spectra of teeth. When operating in vivo, radiation induced spectra are obtained from intact teeth placed within a magnetic field and with a resonator having a loop and two capacitors formed in metal layers on a printed circuit substrate and located near teeth. The resonator is magnetically coupled to an RF measuring system. The spectra are used to determine radiation dose of a subject. The characteristics of the method and the apparatus make it feasible to utilize the system to measure radiation dose using previously untrained operators working in the field under emergency conditions.