What term describes tissue that absorbs little of the x-ray beam and appears dark on a radiograph?

The term that describes tissue which absorbs little of the x-ray beam and appears dark on a radiograph is radiolucent. This is because radiolucent tissues, such as air or soft tissue, allow more of the x-rays to pass through them, resulting in less exposure on the radiograph. The areas that appear dark on the film indicate a higher degree of transparency to x-ray radiation.

In contrast, radiopaque substances absorb more of the x-ray beam, appearing lighter on the radiograph due to less penetration of radiation. An example of radiopaque tissue would be bone, which has a dense structure that absorbs x-rays well. The terms opaque and translucent specifically relate to the visibility through a material but are not used in radiographic terms; opaque means not able to be seen through, while translucent suggests some degree of visibility, often associated with materials that allow partial light transmission but does not apply to radiographic appearances.

Thus, the selection of radiolucent accurately reflects the characteristic of certain tissues as seen in imaging, emphasizing the relationship between their density and x-ray penetration.