ASSESSMENT OF DOSE INDICATORS FOR CT LOCALIZATION PROCEDURES IN RADIATION THERAPY AT UNIVERSITY HOSPITAL RIJEKA

Computed tomography has become a standard tool in radiation therapy treatment planning. Additionally, there is a growing awareness of the dose delivered to the part of the body outside the target volume. Ionizing radiation carries a stochastic risk of malignancy, therefore doses should be kept as low as reasonably achievable in order to provide an adequate information needed for radiotherapy planning. The objective of this work was to set up initial diagnostic reference levels and correlate to image quality that would be used in the future optimization of localization scans. To quantify the doses from computed tomography localization scans at University Hospital Rijeka, local diagnostic reference levels were established for five most common procedures of different anatomical regions ; head, head and neck, pelvis, breast and thorax. Computed Tomography Dose Index volumetric and Dose-Length Product were used as dose indicators and scanning parameters were also recorded. Image quality assessment was performed for each set of images. Results were compared to the seldom published data in order to compare clinical practice. Image quality for almost all of the body regions are scored in average as acceptable but require improvement. It is shown that the optimization of radiotherapy protocols is required therefore these results will be used as a guideline for that process. The establishment of the national diagnostic reference levels for computed tomography localization procedures in radiation therapy is the next step and is currently an ongoing process