Medical physics Flashcards
What is the X-ray photon energy range for a simple scatter?
1-20KeV
Describe a simple scatter
The X-ray photon interacts with an electron in the atom but doesn’t have the energy required to remove the electron so it just bounces off with no change to it’s energy
What is the energy level for the photoelectric effect?
Less than 100KeV
Describe the photoelectric effect
The X-ray photon is absorbed by an electron in the atom. The electron uses the energy to escape the atom
What is the energy range for the Compton scatter?
0.5-5 MeV
Describe the Compton scatter
The incoming X-ray photon interacts with an electron within the atom. The electron is ejected from the atom and the X-ray photon is scattered with reduced energy
What is the energy range for pair production?
anything greater than 1.02 MeV
Describe pair production
An X-ray photon interacts with the nucleus of an atom. The energy of the photon is used to create an electron and a positron
Name two contrast medium
Iodine and Barium
Ultrasound is a
longitudinal wave of frequency greater than 20000 Hz
What is the frequency of ultrasound used in medical physics?
1-15 MHz
What is the advantage of ultrasound over other imaging techniques?
Non ionising
Non invasive
Fast
What is an ultrasound produced by?
A transducer using a piezoelectric crystal with an alternating pd across it
Name a typical material used as a piezoelectric crystal?
quartz
Ultrasound is detected by
a transducer using a piezoelectric crystal which is vibrated by the returning pulse
