Advanced Patient Assessment Practice Exam 2026 – Comprehensive Prep Resource

The correct representation of the four distinct densities recognized in X-rays, from higher to lower density, is bone, water, fat, and air. This ordering is based on the radiographic appearances of different tissues, which vary in their ability to absorb X-rays.

Bone is the densest tissue and appears the lightest or whitest on an X-ray due to its high calcium content, which significantly attenuates the X-ray beam. Following bone in density is water, which presents as a grey tone on the X-ray. Water includes soft tissues and organs where the density is less than that of bone but still substantial enough to block some X-rays. Fat is less dense than both bone and water, resulting in a darker appearance on the radiograph. Lastly, air is the least dense and appears as dark areas on X-rays, as it does not block X-rays effectively.

This hierarchical understanding of tissue densities is essential for interpreting X-rays, as it aids healthcare professionals in identifying and distinguishing between various structures and potential abnormalities. The other combinations do not accurately reflect the correct order of tissue densities as recognized in radiographic imaging.