Abstract:
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Purpose: Evaluation of the performance of a CT system with Flat Panel detector.
Methods and Materials: The system consists of a CT gantry (Somatom Sensation 16, Siemens Forchheim, Germany) with a small focus x-ray tube where the standard detector has been replaced by a Flat Panel a-Si detector with a CsI scintillator. The system records 580 frames during a 360 degree rotation taking 20 s. Each frame consists of 1024x768 binned pixels. The (binned) pixel size is 388 microns. To ensure proper timing, the system is run in pulsed mode with a 50 % x-ray on time. A filtered 3D backprojection with optimized geometry is used for reconstruction. Thicker slices can be obtained by averaging axial images. We evaluate spatial resolution, low contrast detectability, signal-to-noise ratio and dose by means of phantom measurements. Additionally, we performed studies with anatomical specimens.
Results: The system shows excellent spatial resolution: the measured in-plane resolution is better than 21 lp/cm, the slice width is less than 0.25 mm in compliance with isotropic resolution. Low contrast resolution is limited due to the low applicable current of 20 mA @ 80kV. However, 10 HU contrasts were visible in a 16 cm CATPHAN with a slice width of 8 mm. Air kerma is in the range of standard CT. Studies with anatomical samples demonstrate the capability of imaging both small details and low contrast objects.
Conclusion: Flat Panel CT systems can provide excellent spatial resolution at limited low contrast detectability.
Questions about this event email: karl.stierstorfer@siemens.com
Stierstorfer PhD, K,
Performance Evaluation of a Flat Panel CT System. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3106932.html
