PET scanner Flashcards
What release positrons?
FDG decays to release positrons.
What causes annihilation?
Positron interacting with an electron.
What does the annihilation cause?
Two gamma rays of opposite direction.
What happens to the gamma rays after been released?
They are detected by gamma camera.
How is point of origin determined?
By the time difference of the gamma ray pair.
Why are two gamma rays produced?
Momentum before is approximately 0, therefore momentum after must be approximately 0, which is done by two gamma rays in opposite directions.
What is acoustic impendance?
The product of density and speed of sound in a medium.
Equation for acoustic impendance.
Acoustic Impendance = Density * Speed of Sound
What causes more reflection?
Large difference in acoustic impendance.
What causes more transmission?
Same acoustic impendance.
Equation for Intensity reflection coefficient
Ratio of reflected to initial intensity = difference ^ 2 / sum ^ 2 (of Z)
