CT densitometry of the lungs: scanner performance.

OBJECTIVE Our goal was to establish the reproducibility and accuracy of the CT scanner in densitometry of the lungs. MATERIALS AND METHODS Scanner stability was assessed by analysis of daily quality checks. Studies using a humanoid phantom and polyethylene foams for lung were performed to measure reproducibility and accuracy. The dependence of the CT-estimated density on reconstruction filter, zoom factor, slice thickness, table height, data truncation, and objects outside the scan field was determined. RESULTS Stability of the system at air density was within approximately 1 HU and at water density within approximately 2 HU. Reproducibility and accuracy for densities found for lung were within 2-3%. Dependence on the acquisition and reconstruction parameters was neglible, with the exceptions of the ultra high resolution reconstruction algorithm in the case of emphysema, and objects outside the scan field. CONCLUSION The performance of the CT scanner tested is quite adequate for densitometry of the lungs.

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