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Presentation during QIBA COPD Lung Density Reference and Consistency Standards Work Group Call. Philip F. Judy June 8, 2011. COPDGene Reference Standard Model 2. Spectral effects 200 mAs – B31f – 5mm – Varied tube potential. Observations.
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Presentation during QIBA COPD Lung Density Reference and Consistency Standards Work Group Call Philip F. Judy June 8, 2011
Spectral effects 200 mAs – B31f – 5mm – Varied tube potential
Observations • CT numbers inside the phantom of foams identified by NIST are sensitive to spectral differences • CT number air inside the phantom is less sensitive to spectral differences than foams identified by NIST • CT number of acrylic inside phantom may useful characterizing the spectral effects on CT number inside the phantom
Observations:Gammex Stack • Substantial variation CT number of densest foam (-684) from sample to sample. • Variation caused by mAs and reconstruction kernel less than 1 HU • Limitation: Variation could be associated with spatial variation • Unexplained effect at lowest foam density
Observations: Comparison scan of stack with scan of single phantom • Still is substantial variation CT number of densest foam (-684) from sample to sample. • Systematic effect observed. • Limitation: Effect could be associated with difference reconstruction field of view.