Standard Test Method for Calibrating and Measuring CT Density

Importancia y uso:

5.1 This test method allows specification of the density calibration procedures to be used to calibrate and perform material density measurements using CT image data. Such measurements can be used to evaluate parts, characterize a particular system, or compare different systems, provided that observed variations are dominated by true changes in object density rather than by image artifacts. The specified procedure may also be used to determine the effective X-ray energy of a CT system.

5.2 The recommended test method is more accurate and less susceptible to errors than alternative CT-based approaches, because it takes into account the effective energy of the CT system and the energy-dependent effects of the X-ray attenuation process.

FIG. 1 Density Calibration Phantom

5.3 This (or any) test method for measuring density is valid only to the extent that observed CT-number variations are reflective of true changes in object density rather than image artifacts. Artifacts are always present at some level and can masquerade as density variations. Beam hardening artifacts are particularly detrimental. It is the responsibility of the user to determine or establish, or both, the validity of the density measurements; that is, they are performed in regions of the image which are not overly influenced by artifacts.

5.4 Linear attenuation and mass attenuation may be measured in various ways. For a discussion of attenuation and attenuation measurement, see Guide E1441 and Practice E1570.

Subcomité:

E07.01

Referida por:

E1441-19, E1441-19, E1814-14R22, E2533-21, E3166-20E01, F3637-23

Volúmen:

03.03

Número ICS:

35.240.80 (IT applications in health care technology)

Palabras clave:

computed tomography; contrast sensitivity; CT density resolution; density calibration; linear attenuation coefficient; mass attenuation coefficient;