Hounsfield units

Principle

Depending on the type of CT scanner and the settings, the result of a CT scan of the same material can be different attenuation coefficient (grey-values). In order to make it easier to compare CT data, espe-cially in medicine, the grey-values of a CT scan are often rescaled to a standard scale. Hounsfield units is such a scaling that uses air and water as a calibration material which is regularly used in medicine.

Tasks

1. Perform a CT scan of the calibration material
2. Recalculate the results to Hounsfield units

Learning objectives

• Attenuation coefficient
• Hounsfield units
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