What is the Hounsfield Unit (HU) value for water?

The Hounsfield Unit (HU) scale is used in computed tomography (CT) to quantify radiodensity relative to the density of water. On this scale, water is defined as having a value of 0 HU. This standardization allows for consistent measurement of other tissues and materials in relation to water's density.

For example, air typically has a negative HU value (less dense than water), while denser structures like bone have positive HU values. The scale facilitates comparisons across different tissues and enhances the diagnostic value of CT images. Recognizing that the value of water is set to 0 HU is crucial for understanding this scale and interpreting CT imaging correctly.