Chapter 1: Photon-Matter Interactions & CT

13 flashcards · Biology · by Kristóf Nagy

1. X-rays

   Photons emitted from outside the nucleus, usually involving electrons.1

2. Gamma rays

   Photons emitted from the nucleus.1

3. Pair production

   The conversion of a photon into an electron-positron pair in the field of the nucleus or an electron. Requires photon energy greater than 1022 keV.2

4. Inelastic scattering

   The process of light scattering in matter where energy is lost.2

5. Mass attenuation coefficient

   A measure of how much a material attenuates X-rays or gamma rays, per unit mass.3

6. K-edge

   The energy at which the mass attenuation coefficient increases sharply due to the photon energy exceeding the electron binding energy of the K-shell.23

7. Characteristic X-rays

   X-rays emitted due to transitions between electron energy levels, resulting in discrete energies.4

8. Bremsstrahlung

   Radiation produced when electrons are decelerated in the Coulomb field of the nucleus.5

9. Lambert-Beer law

   Describes the exponential attenuation of radiation through a material.6

10. Contrast

    The difference in intensity between two regions of an image.789

11. Flat panel detector

    Modern X-ray detectors that use a scintillator crystal to convert X-rays into visible light, which is then detected by a photodiode.1011

12. Silver halide

    A light-sensitive material used in traditional X-ray film.10

13. Microcalcification

    Tiny calcium deposits that can be a sign of early breast cancer.8