Characteristics of a tandem system of ionization chambers in X-ray beams, mammography level.

Two parallel plate ionization chambers (inserted in slab phantoms) recently assembled at IPEN were studied in relation to their operational characteristics for use in quality control of X-ray beams, mammography level. The chambers present only one difference: one has an inner collecting electrode made of graphite and the other, of aluminum. These chambers make up a tandem system, which may be employed to verify X-ray beams energy constancy, by the confirmation of half-value layers and effective energies, and to determinate air kerma rates. The chambers presented good results for the operational tests, as recommended internationally.