Towards Establishing National Diagnostic Reference Levet From Computed Tomography in Syria - A Pilot Study

Computed Tomography (CT) represents an important and powerful tool for diagnosis and treatment planning nowadays. Its ability to produce high resolution tomographic 2D images with three dimensional representations permits to practicing physicians to obtain more accurate and fast medical decisions which explain the vast increase in CT procedures performed yearly. However, the associated radiation dose with this imaging modality was relatively important which incorporate with an increased carcinogenesis risk to patients. Therefore, the radiation protection rules in terms of justification and optimization should be respected in order to minimize the relevant radiation hazards. The International Commission on Radiation Protection (ICRP) introduced the Diagnostic reference levels(DRLs) in 1996 as an optimization process to identify the abnormalities in the radiation doses delivered to patients in radiological diagnostic modalities through the comparison with a dose threshold balancing between the diagnostically desired image quality and its related radiation dose. Moreover, the DRLs are recommended to be determined on a national or regional data so it could meet the national requirements which falls in with ALARA principle (as low as reasonably achievable). In Syria, the number of CT scanned patients and the range of CT examinations were also increased. The aim of the present study is to investigate the current radiation dose for several adult CT procedures using two dosimetric quantities: dose length product (DLP) which quantify the total radiation dose delivered to patient during CT scan and the CT volume index (CTDIvol) as an indicator to the radiation output of CT scanner. These CT dose quantities are provided by the CT scanners at the end of each scan and they are recommended by the ICRP to establish CT diagnostic reference level. A pilot study was conducted in two major teaching hospitals in Damascus for two months in 2019: ALBAYROUNI University Hospital and ALASSAD University hospital, where two multi-slice CT scanners are available: Siemens SOMATOM Perspective 64 slices and Toshiba Activation 16 slices.