[Evaluation of the absorbed dosage in Compton tomography].

Tomographic images with electronic density can be obtained by irradiation with a monoenergetic beam and detection of the scattered Compton photons. The results of a dosimetric study on the beam of an irradiating Compton unit (equipped with two 192Ir 277.5 GBq sources) are here presented. Doses along the central axis of the beam were measured using thermoluminescent LIF-100 dosimeters. Measurements were taken both in water (RFA-3 Therados) and in cork phantoms. Isodose distributions were estimated by reading the automatic photo-densitometry of radiographic films. A simple algorithm for calculating depth dose values was obtained by analyzing experimental data. The mean absorbed dose (mad) in soft tissues (up to 25 cm deep) was 2.81 mGy for a work load of 7.4 X 10(11) Bq min. The mad in standard thorax was calculated also, which amounted to 3.78 mGy.