A study on image quality was developed using 15 tomography images collected over a head anthropomorphic phantom. The physical region of the phantom was used to analyze contrast resolution. The technology used for tomographic acquisitions was a  Siemens Sensation 64. Tube current (mA), kVp, tomographic slice thickness and acquisition time per view were the scan variables changed between tomographies, looking for the best scan conditions which permit correct contrast resolution with the lowest dose. Kerma-air in air was also measured and its index C_a,100 (mGy) was calculated as dose  indicator. Contrast resolution and detection limits of the CT machine were studied with the Rose Model application. Objective image quality metrics as contrast to noise ratio (CNR), image contrast and global signal to noise ratio (SNR) were calculated over the tomographic images and a visual subjective expert analysis were done to compare with the model results.

The study showed that is possible to reduce the dose, reducing mainly the mAs, without affecting contrast resolution and signal’s detectability with the technology monitored. An optimized acquisition protocol was then proposed.