Date(s) - 09/23/2013
The scientific and clinical debate about the increased risk of biological effects resulting from Computed Tomography (CT) studies has steadily continued in the past few years. A number of publications in reputable medical journals have justifiably brought the issue to the center of attention of the medical community, but it has also created an atmosphere of fear among patients and families. However, none of these papers are based on any reliable determination of patient dose, either based on reliable simulations and mathematical models or actual organ dose measurements. For obvious reasons, in vivo organ dose determinations are limited to surface measurements which can be used to estimate internal doses. For the past three years, the group at Radiology has been utilizing cadavers to replicate the conditions of an actual CT study with the understood ability to perform actual point dose measurements in all internal organs with the use of optically-stimulated luminescent (OSL) dosimeters, a technique also originally developed in our group. To date, we have utilized 9 cadavers and have established a number of conclusions: first, we have established that the x-ray attenuation characteristics of post-mortem organs are equivalent to those of living tissues; two, that we have established a reliable and reproducible internal dose measurement method, which yields reproducible results; third, that we have developed an empirical method by which organ dose measurements can be determined by entering the type of study (anatomical site), the scanner-reported CTDIvol and the patient’s effective diameter at the torso or the head level, as applicable. We are now evaluating the impact on patient dose from new iterative reconstruction algorithms and modified tube current modulation application based on patient table positioning, as well as the impact on image quality from these new features.