ON THE ACHIEVEMENT OF OPERATIONAL RADIATION PROTECTION QUANTITIES FORMIXED PHOTON-NEUTRON RADIATION-FIELDS

In calibration fields for penetrating radiation, operational radiation protection quantitites such as H(10) and H-p(10) are commonly derive d from measurable quantities (spectral fluence for neutrons,, air kerm a for photons) and calculated fluence to dose equivalent coefficients for neutrons and kerma to dose equivalent conversion coefficients for photons. The paper presents a theoretical study on the suitability of a small tissue-equivalent proportional counter (TEPC), inserted at a d epth of 10 mm in a phantom, for measuring H(10) and H-p(10). The diff erences between the definition of dose equivalent and the measurement principle of the TEPC are discussed. If the pressure of the TEPC gas f illing, the phantom material and size are all correctly chosen, a read ing which deviates by less than +/-25% from H-p(10) for photons and ne utrons impinging on the phantom from the entire front hemisphere can b e obtained.