What does the term "attenuation" refer to in CT imaging?

The term "attenuation" in CT imaging refers to the reduction of radiation as it passes through various tissues in the body. When X-ray photons encounter different types of tissues—such as bone, muscle, or fat—they lose energy, resulting in differing amounts of radiation that reach the detector. This differential attenuation is what allows CT scans to create images with varying contrast levels, highlighting anatomical structures based on their composition.

In practical terms, tissues that are denser, like bone, will attenuate the X-ray beam more significantly than softer tissues, leading to clearer distinctions in the CT images. This fundamental concept underlies many aspects of CT imaging, including how contrast agents can be used to enhance the visibility of certain structures by altering the attenuation characteristics of specific tissues.

Understanding attenuation is crucial for interpreting CT images and optimizing scan parameters to achieve the best possible diagnostic information.