Room: AAPM ePoster Library
Purpose: verify detection capabilities of composition/size of urinary stone in accordance with CT parameters and the phantom size changes by using the dual-energy CT scan.
Methods: human urinary stones comprising uric acid(n=7), Calcium oxalate monohydrate(n=9), Calcium oxalate monohydrate+Carbinate apatite+struvite(n=6), Calcium oxalate monohydrate+Struvite(n=4), Calcium oxalate monohydrate+Calcium oxalate dihydrate+cabinate apatite (n=2), Cabonate apatite+Struvite (n=1), and Struvite(n=1) were inserted between 2 Boluses(30×30×1 cm) and placed inside solid water phantom(30×30×1 cm). Spiral dual-energy scans were obstained on dual-source, 128-slices computed tomography(CT) system using a clinical protocol and automatic exposure control. Scanning was performed at two different collimation/slicethickness, Increment(64×0.6 mm and 128 ×0.6 mm, 0.5/0.5 mm and 1.5/1.0 mm Recon) and within three phantom size(small, medium, Large) resulting in a total of five image datasets. These datasets were analyzed using the dual-energy software tool(SIEMENS SyngoVia) available on the CT system for both sensitivity(number of urinary stone detection) and accuracy(diameter of urinary stone detection). In addition, it was confirmed a match with the external urinary stone component analysis result.
Results: choice of TestA(64 × 0.6 mm collimation, 80/sn140 kvp, 0.5 mm slicethickness/0.5 mm Increment) suggests a high sensitivity(87%) and accuracy(73%) in the three phantom size(small, medium, Large). When the size of uric acid urinary stone is greater than 2.5/4.5 mm or greater than 1.5/2.5 mm the size of apatite+oxalate urinary stone detection is possible. In order to enhance accuracy, it is important to thicken the height of the phantom, and to select the 64×0.6 mm; since the result using the 128×0.6 mm showed significant errors. TestA experimental conditions, the accuracy of urine stone component analysis using the software tool(SIEMENS SyngoVia) was 93%.
Conclusion: the dual-energy CT exam used for urinary stone detection, TestA(64×0.6 mm Collimation, 80/sn140 kVp, 0.5mm slicethickness/0.5 mm Increment) was the best choice to get the sensitivity, accuracy and precision of urinary stone composition.