Institutional patient doses in computed tomography angiography
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Αραβαντινού, Αναστασία
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Abstract
Computed Tomography Angiography (CTA) is an imagig modality that combines a CT scan with an injection of a special dye to produce pictures of blood vessels in a part of the body. During the last years CTA examinations have increased a lot, so there is need for optimization of the patient dose. In this study the institutional doses for CTA examinations for carotids, chest and abdomen, in the University Hospital of Patras are presented. The systems that have been used were Toshiba Aquilion Prime (80 slices) and General Electric Lightspeed 16 (16 slices). Totally 175 patients participated in this study, 30 of each examination for the Toshiba scanner and 85 for the GE scanner. The patient characteristics age, sex, body mass index (BMI) for the Toshiba scanner and sex for the GE scanner, were recorded. To calculate the patient dose, the dose indexes utilized were Computed Tomography Dose Index (CTDIvol), Dose Length Product (DLP) and we calculate the Effective Dose (ED) using the DLP values. The 75th percentile of DLP distribution was calculated for comparison purposes. For Toshiba CT scanner the 75th percentile of CTDIvol values in carotids, chest, abdomen examinations were 5.45 mGy, 5.88 mGy, 7.05 mGy, whilst the DLP values were 209.90 mGy·cm, 227.80 mGy·cm, 342.45 mGy·cm, respectively. For the GE scanner the corresponding CTDIvol values were 36.98 mGy, 12.78 mGy, 22.48 mGy, whilst the DLP values were 1396.01 mGy·cm, 455.65 mGy·cm, 1093.31 mGy·cm, respectively. The dosimetric indexes (CTDIvol, DLP) for the three types of examinations (carotids, chest and abdomen) carried out in our hospital utilizing an 80-slice CT system were lower than that of the 16-slice CT system by (85%, 85%), (54%, 50%) and (69%, 69%) respectively for the three types of examinations. Specifically, for the specific 80-slice CT system we have in particular: a) for the carotid examination, the DLP value of 209.90 mGy•cm (which is related with the evaluation of ED) was found to be lower than that of the comparing studies except one which was 37% lower using an 320-slice CT system, b) for the chest examination, the DLP value of 227.80 mGy•cm was found to be lower than that of the comparing studies except one which was 16% lower using a 64-slice CT system mainly to the smaller SL, c) for the abdomen examination, the DLP value was found to be lower than that of the comparing studies except one study which was 19% lower using an 128-slice CT system.
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Computed Tomography Angiography (CTA), Δόση ασθενούς