A study of the dose modulation systems in two multislice CT scanners

Multislice computed tomography (TCMC) is a technique that for its gradual introduction and the spectacular increase in its indications in clinical practice represents the main contribution to the collective dose in diagnostic radiology. It is essential to optimize the protocols maintaining doses as low as possible without affecting the diagnostic quality of images. Automatic tube current modulation systems are a tool currently available in all CT scanners. They adapt the tube current to morphological characteristics of the patient and the anatomical area under study. The aim of this work has been to analyze two scanners from the same manufacturer and featuring similar geometry by assessing the relative dose differences and image quality. Modulation systems of general use can decrease the dose in a 20-60% with a reduction in the signal to noise ratio between 6% and 37%. Dedicated cardiac-CT modulation system gave rise to high relative differences (36-40%) even when varying the heart rate. Significant changes in image quality were not appreciated though the motion of the heart has not been simulated in this study. (Author) 14 refs.