Program Information

Improving Prostatic Delineation Using Dual-Energy CT

J Gersh*, D Fried , Gibbs Cancer Center & Research Institute - Pelham, Greer, SC

Presentations

SU-E-I-78 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: Visual prostatic definition is difficult using conventional CT. This is because the prostate is surrounded closely with tissue of similar electron density. Definition is further hindered when the region contains high-Z material (such as fiducial markers). Dual-energy CT (DECT) is a technique where images are rendered using two tube voltages during a single scan session. This study evaluates DECT as a means of improving prostatic volume delineation for radiation oncology.

Methods: The patients were scanned using a Definition AS20 (Siemens Healthcare, Malvern, PA). This device uses a single-tube configuration, where two scans of differing energies are performed in serial. The scans are acquired with tube voltage of 80kVp and 140kVp. Following acquisition, these scan data were used to generate effective monoenergetic scans ranging from 40keV to 190keV. In the current study, the data were presented to observers using a novel program which allows real-time adjustment of window, level, and effective keV; all while scrolling through volumetric slices. Three patients were scanned, each with a different high-contrast material in or around the prostate: I-125 seeds, gold fiducial markers, and prostatic calcifications. These images are compared to a weighted average of the 80kVp and 140kVP scans, which yield a scan similar to that of a 120 kVp scan, which is a common tube voltage in radiation oncology.

Results: Prostatic definition improved in each case. Differentiation of soft tissue from surrounding adipose improved with lower keV, while higher keV provided a reduction of high-z artifacts. Furthermore, the dynamic adjustment of the keV allowed observers to better recognize regions of differing tissue composition within this relatively homogeneous area.

Conclusion: By simultaneously providing the observer with the benefits of high-energy images and low-energy images, and allowing adjustment in real-time, improved imaging in highly homogeneous regions such as the male pelvis is achievable.

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