Radiographic X-Ray Photon Attenuation

Biomedical Engineering

How It Works

Diagnostic radiography and CT imaging depend on differential photon attenuation as ionizing radiation traverses biological tissues. In accordance with the Beer-Lambert law, incident photon intensity decreases exponentially with penetration depth. High-density cortical bone exhibits a high linear attenuation coefficient (μ) dominated by photoelectric absorption, casting a clear radiographic contrast shadow compared to soft tissue.

Governing Equation
I(x) = I₀ · e^(-μ · x) , HU = 1000 · ((μ_tissue - μ_water) / μ_water)