An assessment of dose indicators for computed tomography localization procedures in radiation therapy at the University Hospital Rijeka

Abstract

The 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. The ionizing radiation carries a stochastic risk of malignancy, therefore, the doses should be kept as low as reasonably achievable in order to provide an adequate information needed for the radiotherapy planning. The objective of this work was to set up the initial diagnostic reference levels and correlate to the image quality that would be used in the future optimization of localization scans. To quantify the doses from computed tomography localization scans at the 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. The Computed Tomography Dose Index volumetric and the Dose-Length Product were used as dose indicators and scanning parameters were also recorded. The image quality assessment was performed for each set of images. The results were compared to the seldom published data in order to compare the clinical practice. The image quality for almost all of the body regions are scored as acceptable in average 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.