9 March 2012 Overcoming x-ray tube small focal spot output limitations for high resolution region of interest imaging
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We investigate methods to increase x-ray tube output to enable improved quantum image quality with a higher generalized-NEQ (GNEQ) while maintaining a small focal-spot size for the new high-resolution Micro-angiographic Fluoroscope (MAF) Region of Interest (ROI) imaging system. Rather than using a larger focal spot to increase tubeloading capacity with degraded resolution, we evaluated separately or in combination three methods to increase tube output: 1) reducing the anode angle and lengthening the filament to maintain a constant effective small focal-spot size, 2) using the standard medium focal spot viewed from a direction on the anode side of the field and 3) increasing the frame rate (frames/second) in combination with temporal filter. The GNEQ was compared for the MAF for the small focal-spot at the central axis, and for the medium focal-spot with a higher output on the anode side as well as for the small focal spot with different temporal recursive filtering weights. A net output increase of about 4.0 times could be achieved with a 2-degree anode angle (without the added filtration) and a 4 times longer filament compared to that of the standard 8-degree target. The GNEQ was also increased for the medium focal-spot due to its higher output capacity and for the temporally filtered higher frame rate. Thus higher tube output, while maintaining a small effective focal-spot, should be achievable using one or more of the three methods described with only small modifications of standard x-ray tube geometry.
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Sandesh K. Gupta, Sandesh K. Gupta, Amit Jain, Amit Jain, Daniel R. Bednarek, Daniel R. Bednarek, Stephen Rudin, Stephen Rudin, } "Overcoming x-ray tube small focal spot output limitations for high resolution region of interest imaging", Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 831358 (9 March 2012); doi: 10.1117/12.910791; https://doi.org/10.1117/12.910791

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