interaction of radiation with matter
When X-rays and gamma-rays fall on an object, some of those photons interact with particles (electrons, protons) of matter, and their energy is either absorbed or scattered. This absorption or scattering of photon is called attenuation. The remaining photons go straight from the particle of any matter without interacting with it.
The number of photons that transmit from a material depends on the thickness, density, atomic number of the material and the energy of each photon.
There is a possibility of four types of reaction when there is an interaction with the matter of an ionizing radiation.
- COHERENT SCATTERING -Radiography / Radiotherapy in ......... Read More
- PHOTOELECTRIC EFFECT - It's an all or none ........ Read More
- COMPTON EFFECT- Photon in this effect .......... Read More
- PAIR PRODUCTION- It is in an energy mass ....... Read More
These four effects lead to the following conclusion -
When absorption is through the photoelectric effect, bone absorbs more energy than soft tissue (up to 6 times more).
Bone and soft tissue per gram absorb the same energy in the case of the Compton effect.
If absorption is only through Pair production, Bone absorbs twice as much energy than Soft Tissue.
Energy effect
UP to 50 keV Photo Electric Effect
60-90 KeV Photo Electric Effect + Compton Effect
200KeV-2 MeV Compton Effect
5 MeV-10 MeV Pair Production begins to important
50 MeV-100 MeV Pair Production most important
