Radiation emission Flashcards
What are the types of radiation emissions?
Alpha particle
Beta positive (beta +ve)
Beta negative (beta -ve)
Gamma rays
What is the structure of an alpha particle?
2 protons and 2 neutrons
Large mass
Properties of alpha particle
High energy (high damage) Short-range (due to high mass) Densely ionizing High linear energy transfer (LET) Positive charge Influenced by electrical and magnetic fields Rest mass 3725 MeV
How do alpha particles occur?
Radioactive decay (unstable atom) disintegrates and emits alpha and gamma rays (energy) to become stable. It kicks out neutrons and protons.
Example of alpha particle being produced?
226/88 Ra = 222/86 Rn + 4/2 a
Notice the decrease in mass/atomic numbers
Radon to radium
How is beta -ve produced?
Produced by a nucleus with too many neutrons
Neutrons transform into proton and β- particle and antineutrono
antineutrono (no mass, no charge)
How is beta +ve produced?
Produced by a nucleus with too many protons, too few neutrons
Proton transform into a neutron and β+ particle and neutrino
neutrino (no mass, no charge)
Example of beta -ve
99/42 Mo = 99/43 Tc + β- + u
Gains a proton
Example of beta +ve
18/9 F = 18/8 O + β+ + u
Loses a proton
Properties of beta particles
High energy
Greater range than alpha particles
Are a charged particle (positive or negative)
Need approximately 4 mm of aluminum to stop them – depending upon the energy
Can be influenced by electrical and magnetic fields
Cause localized tissue damage
How are gamma rays produced?
Following the emission of a particle from the nucleus, the daughter nucleus is left in an excited state
The nucleus sheds this excess energy in order to achieve stability
Gamma-ray emission is almost instant following particle emission except in isomeric (metastable) transition
Uses of gamma rays
Gamma ray emission is important in metastable elements because it allows imaging of the patient with a relatively low radiation dose
Gamma ray emission at high energies allows radiotherapy sealed source treatment for localised tumours e.g. Iridium, Tantalum, Caesium
What are isomers?
Same atomic number but different energy levels.
Add an m next to mass number to identity these
Properties of gamma rays.
Have no charge
Not affected by electrical or magnetic fields
Less destructive than alpha or beta particles generally have a lower LET
More penetrating than alpha or beta particles
Need a heavy metal (Lead) to attenuate them (5cm For Co60)
What is a decay scheme?
Decay schemes are diagrams/graphs to show energy emission represent either positive or negative beta decay processes
