X-ray imaging

X-rays and CT scanning

X-rays are produced when high-speed electrons hit a metal target. An electron accelerated through p.d. $V$ can give at most all its energy $eV$ to one photon, so the minimum wavelength is $\lambda_{\min}=\dfrac{hc}{eV}$. X-rays are attenuated exponentially in matter: $I=I_0e^{-\mu x}$. Bone attenuates much more than soft tissue, giving contrast. CT scanning combines images from many angles to build 2D slices, then stacks them into a 3D image.