Feasibility of dose assessment in radiological diagnostic equipments using Ce-doped radio-luminescent optical fibers

A mammography system, a conventional radiological equipment and a CT scanner operated at 120 kV were used to investigate the reproducibility, the sensitivity and the response linearity to a variety of X-ray tube current, high-voltage and dose values of a radio-luminescent dosimeter based on a Ce-doped optical fiber.The dosimeter reproducibility was very close to the ionization chamber reproducibility. The detector sensitivity was also calculated in order to evaluate the minimum detectable dose rate and a minimum detectable dose, considering a sampling time of 10 ms.All curves have a very good linear course with a correlation coefficient greater than 0.999.The fiber sensitivity (counts per unit dose) as a function of the X-ray tube voltage obtained with the conventional X-ray equipment decreases by increasing the photon energy, losing about 10% of its value from 60 to 120 kV. Also for CT scanner, the fiber responses are very good and reproducible.The new dosimetric system is complementary to usual dosimetry systems as ionization chambers, since it is mostly suitable for in vivo and on-line dosimetry. Scintillating fibers are very safe because they are not electrically powered and moreover they assure very high spatial resolution due to their reduced dimensions.