CAMRT Radiography Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

The typical CT value for air is indeed around -1000 Hounsfield Units. This value represents the density of air in comparison to water, which has a CT value of 0. CT values, or Hounsfield Units, are used in computed tomography to quantify the relative density of different tissues based on their atomic composition, with air being one of the least dense materials in the body.

In CT scanning, the lower the Hounsfield Unit value, the less dense the material is. Air, when imaged, shows a very low density due to its gaseous state, thus reflecting a value close to -1000. This allows radiologists and clinicians to differentiate air-filled spaces from soft tissues and bones, which have higher CT values. Being able to identify and interpret these values is essential when analyzing CT images for diagnostic purposes.