ASTM E1695 Computed Tomography (CT) System Performance

The spatial resolution and contrast sensitivity of X-ray and γ- ray computed tomography (CT) volumes are determined using the standard test method ASTM E1695. The result is determined by looking at the CT volume of a uniform cylinder of material. The values expressed in SI units should be considered standard.

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Scope:

ASTM E1695 test method evaluates and summarizes the overall performance of a CT system. Separate documents, especially Guide E1000, Practice E2737, and Practice E2002, cover performance tests of system components such as X-ray tubes, gamma sources, and detectors and should be consulted for additional system analysis. ASTM E1695 allows the buyer or seller of CT systems or services, or both, to assess and specify the spatial resolution and contrast sensitivity, as well as system stability and performance acceptability.

Procedure:

The phantom is installed on the CT system according to ASTM E1695. The parameters for data capture should be identical to those used for inspection object scans. One slice is captured and evaluated in a fan-beam CT. Three slice planes intercept the phantom cylinder at different points of the detector in a cone-beam CT. Each plane’s MTF (Modulation Transfer Function) and CDF (Contrast Discrimination Function) are measured separately.

Specimen size

In ASTM E1695, the cylinder’s diameter must be large enough for the reconstruction to take up at least 250 voxels in the final image. The cylinder’s height should be 80 percent of the detector’s height.

Result

For ASTM E1695, the report outcome should include all relevant data that influences the MTF and CDF measurements. The result report represents the MTF and the CDF graphically.

Conclusion:

ASTM E1695 test method evaluates and summarizes the overall performance of a CT system.