domain I - ionizing radiation physics & detections

protons

positive charge

neutrons

no charge

electron

negative charge

atomic #

number of protons

mass #

protons + neutrons

isotopes

are atoms of same element that have same number of protons but different neutrons

gamma decay

• high energy

• no mass

• no charge

• nucleus losing energy

• can escape patient and be directed outside of body

  • used for imaging: Tc-99m, In-111, I-123

beta minus decay

• particle is an electron emitted from the nucleus

• a neutron changesto a proton & atomic # increases by 1 mass # stays the same

• beta particles deposit energy over a short distance & can be used for therapy : I-131, Lu-177, Y-90

alpha decay

alpha particle contains 2 protons & 2 neutrons

mass # decreases by 4

atomic # decreases by 2

positron emission

a positron is the antimatter version of electron, has the same mass as an electron, has a positive charge

• a proton changes into a neutron: atomic # decreases by 1 & mass # stays the same

positron annihilation

positron travels a short distance and encounters an electron; this produces 2 photons w/ 511keV and they travel opposite directions 180 degrees

bremsstrahlung radiation

meaning "braking radiation" from German—is electromagnetic radiation created when a fast-moving charged particle, like an electron, slows down or changes direction as it passes near a heavy, positive atomic nucleus. As the electron loses speed, its lost energy turns into a photon

Describe Characteristic X-ray

An electron is ejected and a less tight bound electron fills in and gives off energy in form of X-Ray (difference between the 2 electrons levels)

NaI well counter

scintillation detector

used for :

• small samples

• wipe tests

ionization chamber

contains gas

dose calibrator

measures activity from radiopharmaceuticals

solid state detectors

use semiconductor materials

good energy resolution, spatial resolution, direct conversions of radiation into electrical signals

• CZT cameras are used in cardiac imaging

geiger muller meter

radiation enters & ionizes gas & creates electrical pulses

used for: contamination surveys, detecting radiation, very sensitive

dose calibrator is

ionization chamber

what measures activity

dose calibrator

ionization chamber

what do you use for wipe tests

well counter

scintillation crystal

NaI

what converts light into electrical signal

scintillation detector

what is a solid state detector

semiconductor

what do you use for contamination surveys

geiger mulle meter

positron annihilation creates…

two 511 keV photons