What does the principle of differential absorption refer to in radiography?

The principle of differential absorption is central to understanding how various tissues in the body interact with X-rays during the imaging process. This principle refers to the varying degrees of X-ray absorption by different tissues, which occurs due to differences in tissue density and atomic composition.

When X-rays pass through the body, they are absorbed to different extents by different types of tissues—denser tissues such as bone absorb more X-rays than less dense tissues such as muscle or fat. This differential absorption is what allows radiographic images to provide useful contrast: areas of high absorption appear lighter on the film, while those with lower absorption appear darker. Understanding this concept is crucial for effectively interpreting radiographs, as it highlights the importance of tissue characteristics in producing a clear and informative image.

The other options do not accurately describe this principle, as they either imply uniform absorption, complete absorption of all X-rays by denser tissues, or focus on measurement aspects unrelated to the interaction between X-rays and body tissues.