X-Ray Imaging Physics for Nuclear Medicine Technologists. Part 2: X-Ray Interactions and Image Formation

Ideal projection radiograph is representation of transmitted primary x-ray fluence from point source through object and incident on detector, as depicted on left for a uniform incident fluence, I₀, and transmitted I₁, I₂, and I₃ fluences through tissue, air, and bone, respectively. Subject contrast is difference in signals of an object to background—for example, (I₁ − I₂)/I₁ and (I₁ − I₃)/I₁. On right is typical situation in presence of scatter, demonstrating loss of subject contrast and smaller difference between incident and transmitted radiation intensity.