K-edge digital subtraction imaging with dichromatic x-ray sources: SNR and dose studies.
The aim of the present work is to analytically evaluate the signal to noise ratio (SNR) and the delivered dose in K-edge digital subtraction imaging (KES) using two types of x-ray sources: a monochromatic x-ray source (available at synchrotron radiation facilities and considered as gold standard) and a quasi-monochromatic compact source. The energy separation DeltaE between the two monochromatic beams is 1 keV and 4 keV for the two sources, respectively. The evaluation has been performed for both radiography and computed tomography. Different geometries have been studied to mimic clinical situations. In mammography, a pathology perfused by a contrast agent has been modelled; in angiography, a vessel superimposed to a ventricle or a stand-alone artery stenosis has been studied. The SNR and the skin dose have been calculated as a function of the detail diameter, the contrast agent (iodine and gadolinium), and its concentration in the tissues. Results show that for DeltaE = 4 keV a slightly higher delivered dose is required to obtain the same SNR with respect to DeltaE < 1 keV. A similar study has been performed for KES-CT. Computer simulations of CT images performed with Snark software are shown to validate the analytical calculations.
Sarnelli
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European Synchrotron Radiation Facility, 6 rue Horowitz, BP 220, F-38043 Grenoble Cedex, France. anna_sarnelli@hotmail.it
Elleaume
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Taibi
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Gambaccini
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Bravin
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D000465:Algorithms; D015901:Angiography, Digital Subtraction / Q000379:methods*; D003287:Contrast Media / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry; D006801:Humans; D007455:Iodine / Q000737:chemistry; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media; D007455:Iodine; D005682:Gadolinium