2016 AAPM Annual Meeting
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Session Title: Dual Energy CT in Radiation Therapy
Question 1: How does the dynamic range in CT signal differ between relative electron density and atomic number at typical CT X-ray energies for bone and contrast agents? Is it:
Reference:Landry et al, Phys. Med. Biol. 2013, Vol 58(19). Deriving effective atomic numbers from DECT based on a parameterization of the ratio of high and low linear attenuation coefficients - http://dx.doi.org/10.1088/0031-9155/58/19/6851
Choice A:Larger.
Choice B:Smaller.
Choice C:Not Significant.
Choice D:Material dependent.
Question 2: Phantom studies comparing estimated accuracy with proton, DECT and SECT found that:
Reference:Yang M, Virshup G, Clayton J, Zhu XR, Mohan R Dong L. Theoretical variance analysis of single- and dual- energy computed tomography methods for calculating proton stopping power ratios of biological tissues. Phys Med Biol 2010; 55: 1343-1362. -Hansen C et al, Acta Oncologica 2015, Vol 59(9). A simulation study on proton computed tomography (CT) stopping power accuracy using dual energy CT scans as benchmark. DOI: 10.3109/0284186X.2015.1061212
Choice A:Calculations of electron density and effective atomic number are lower for DECT than for SECT .
Choice B:Proton CT gave slightly better stopping power estimates than DECT.
Choice C:Stopping power estimates were worse using SECT than DECT.
Choice D:All of the above.
Question 3: Which of the following statements is correct regarding monoenergetic image reconstruction of dual-energy CT data?
Reference:1. Marin D. State of the art: dual-energy CT of the abdomen. Radiology 2014; 271(2):327-42. 2. Mileto A et al. Impact of dual-energy multi-detector row CT with virtual monochromatic imaging on renal cyst pseudoenhancement: in vitro and in vivo study. Radiology 2014; 272 (3):767-76
Choice A:Are used to generate an iodine map.
Choice B:Are generated subtracting iodine from a post-contrast data-set.
Choice C:Low kV data-sets improve the detection of iodine uptake.
Choice D:Low kV data-sets reduce the detection of iodine uptake.
Choice E:High kV data-sets improve the detection of iodine uptake.
Question 4: Which of the following statements is correct regarding virtual unenhanced images derived from dual-energy CT?
Reference:De Cecco CN, et al. Virtual Unenhanced Images of the Abdomen with Second Generation Dual-Source Dual-Energy Computed Tomography: Image Quality and Liver Lesion Detection. Invest Radiol 2013;48(1):1-9.
Choice A:Are useful to quantify iodine uptake.
Choice B:Are generated subtracting iodine from a post-contrast data-set.
Choice C:Are used to generate different kV data-sets.
Choice D:Can be generated only from an arterial phase data-set.
Choice E:Improve the detection of iodine uptake.
Question 5: What of the following is not a technique for obtaining different x-ray spectra for the energy measurements:
Reference:Reference: Computed Tomography: Principles, Design, Artifacts, and Recent Advances, Hsieh J, 3rd edition, SPIE Press, 2015.
Choice A:Different kVp
Choice B:Different filtration
Choice C:Different reconstruction kernel
Choice D:Energy discriminating detector
Question 6: The principal advantage of raw data (or sinogram) domain spectral processing versus image domain spectral processing is:
Reference:Computed Tomography: Principles, Design, Artifacts, and Recent Advances, Hsieh J, 3rd edition, SPIE Press, 2015.
Choice A:Registration of the raw data is not required.
Choice B:Accurate beam hardening can be included.
Choice C:It is simpler to implement.
Choice D:All of the above.
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