Radiation Dose of Computed Tomography Pulmonary Angiography Examinations using Size -Specific Dose Estimate

In recent times, there has been a growing concern regarding the potential risks associated with radiation exposure from computed tomography (CT) scans as a diagnostic tool. One of the methods used to optimize the radiation dose received by patients is the implementation of diagnostic reference levels (DRLs). CTDIv (Volume Computed Tomography Dose Index) and DLP (Dose Length Product) are utilized to evaluate and establish Diagnostic Reference Levels (DRLs). The CTDIv has limitations in accurately estimating the patient dose, which is why the American Association of Physicists in Medicine (AAPM) has introduced SSDE (Size-Specific Dose Estimates) as a method for more precise estimation of patient radiation dose. In this study, the DRLs of CT pulmonary angiography (CTPA) examinations of adults is determined using CTDIv, DLP and SSDE. ۲۰۰ CT examinations of pulmonary angiography were collected from PACS (Picture archiving and communication system) in Chamran hospital. The diameter effective (Deff), conversion factor (CF) and SSDE calculated using AAPM TG -۲۰۴ and TG -۲۲۰. Statistics analysis calculated using SPSS version ۱۸. All scans in the study were performed using the GE Healthcare ۱۶ Slices CT scanner. For the injection protocols, a Medtron injector was utilized. Imaging includes two stages test bolus and pulmonary angiography. During the test bolus imaging, a volume of Visipaque between ۱۲ to ۱۸ ml was administered, while in the pulmonary angiography imaging, a volume of Visipaque between ۳۰ to ۴۰ ml was administered. For test bolus, imaging third quartile of CTDIV, SSDE and DLP was ۱۵۲.۴۵ to ۳۱۰.۲۵, ۲۱۵.۲۵ to ۴۳۸.۷۲ and ۱۵۲.۴۵ to ۳۱۰.۲۵ and values of ۱۲.۵۴ to ۱۵.۶۵, ۱۷.۷۰ to ۲۲.۰۹ and ۴۳۲.۲۵ to ۵۲۱.۶۵ are determined for pulmonary angiography, respectively that are lower than national DRLs. In addition, calculated CF for pulmonary angiography was ۱.۴۱۲ ± ۰.۱۷. DRLs were lower than other studies in this study. Using the AEC (Auto Exposure Control) and different kVp in this hospitals can help optimization of patient dose. The SSDE must be calculable by radiographers to more accurate estimation of patient dose using CFs.

Keywords:

Chest , CT Arteriography , SSDE , TG ۲۰۴ , TG ۲۲۰