Organ Dose Measurements on X-Ray CT Examinations among Different Kinds of Apparatuses

X-ray CT apparatuses have been developed as one of very effective diagnostic tools, and been evolved from single to multi-detectors, and single to helical type scanning methods. On the contrary, the doses of patients on X-ray CT examinations are obviously higher than those of general radiographies. In recent, X-ray CT apparatuses have been used for chest examinations of mass-screenings in Japan, and the factors influencing doses of patients are concerns on radiation protection. For estimating the differences by the factors such as beam width and pitch etc. quantitatively, the organ doses of X-ray CT examinations for typical three X-ray CTapparatuses of different manufactures were directly measured by using thermoluminescence dosimeters and an adult anthropomorphic phantom as the values of normalized organ doses per mAs and effective mAs for the factors. The half-value layers (HVLs) of X-ray CT apparatuses were also measured. The differences of organ doses between the highest and lowest were approximately two times. The organ dose variations among manufactures could be explained by the HVLs as one of the reasons. For the same apparatus, the organ doses were different depending on the factor values (Fig. 1 and 2). The result suggests that the organ doses can be different depending on the kinds of apparatuses even though same X-ray CT examinations would be performed.Xth EFOMP Congress - Pisa 200