Measurement of effective atomic numbers using energy-resolved computed tomography

Abstract

For ion radiation therapy, the measurement of effective atomic numbers, Z[eff], is necessary to know the material distribution in a human body; the range of ions entering the human body is influenced by the material distribution along their paths. Z[eff], however, cannot be measured at hospitals because monochromatic X-rays with different energies are necessary and are used only at synchrotron facilities. To make Z[eff] measurements at hand, we propose energy-resolved computed tomography (CT) using a “transXend detector”. By assigning two narrow energy ranges in the unfolding process of the data obtained by the transXend detector, Z[eff] for acrylic and aluminum can be estimated by energy-resolved CT. The estimated Z[eff] are compared with those obtained by dual-energy and monochromatic X-ray CT.