Document Type : Original Paper
Istituto Nazionale di Fisica Nucleare (INFN), via Giuria 1, 10125 Torino, Italy Dipartimento di Fisica Sperimentale, Universita’ di Torino, via Giuria 1, 10125 Torino, Italy Presently at the Nuclear Science Research School, Nuclear Science and Technology Research Institute, Tehran, Iran
Fondazione CNAO, strada Campeggi, 27100 Pavia, Italy
Istituto Nazionale di Fisica Nucleare (INFN), via Giuria 1, 10125 Torino, Italy Dipartimento di Fisica Sperimentale, Universita’ di Torino, via Giuria 1, 10125 Torino, Italy
Dipartimento di Fisica Sperimentale, Universita’ di Torino, via Giuria 1, 10125 Torino, Italy
Hadron-therapy is an effective technique used to treat tumors that are located between or nearby vital organs. The Italian National Center of Oncological Hadron-therapy (CNAO) has been realized as the first facility in Italy to treat very difficult tumors with protons and Carbon ions. The on-line monitor system for CNAO has been developed by the Department of Physics of the University of Torino and Italian National Institute of Nuclear Physics (INFN). The monitoring system performs the on-line checking of the beam intensity, dimension, and beam position.
Materials and Methods
The monitor system is based on parallel plate ionization chambers and is composed of five ionization chambers with the anodes fully integrated or segmented in pixels or strips that are placed in two boxes. A series of measurements were performed that involve the background current and the detectors have been characterized by means of a series of preliminary testes in order to verify reproducibility and uniformity of the chambers using an X-ray source.
The measured background currents for StripX, StripY and Pixel chambers are five orders of magnitude smaller than the nominal treatment current. The reproducibility error of chambers is less than 1%. The analysis of the uniformity showed that the monitor devices have a spread in gain that varies, but only about 2%.
The reproducibility and the uniformity values are considered as a good result, taking into account that the X-ray energy range is several orders of magnitude smaller than the particle energies used at CNAO.