Ionising Radiation Flashcards
What are the characteristics of ionising radiation
Penetrating
Invisible to the eye
Can cause tissue damage
What are examples of natural radiation
Cosmic, animals, buildings, food, people, radon gas
What are examples of artificial radiation
Medical imaging, nuclear power, missiles and nuclear weapon testing
What is a half value layer
The thickness of a substance which will transmit one half of the intensity of radiation incident upon it
What is a half life
Time taken for half of the atoms to decay
True or false - you can predict when an individual atom will decay
False - it is impossible as radioactive decay is a random process
What are we able to predict involved with half lives
The fraction of the atoms that will decay over a period of time
What is the inverse square law
The concentration of radiation is inversely proportional to the square of the distance - intensity reduces with distance
What are the 3 practical principles of radiation safety
Time distance shielding
What is the lead equivalence
The lead equivalent of an absorbing material is the thickness of lead which would absorb the same amount of radiation as the given material when exposed to radiation of the same type
What is radon gas
Chemical element with the atomic number of 86 - it is a radioactive colourless and tastelesss gas
How is radon gas formed
Radioactive decay of small amounts of uranium that occur naturally in rocks and soils
What is the banana equivalent dose
Informal way of comparing doses of radiation to the dose received by eating a single banana
What is radioactive decay
Process of an unstable atomic nucleus loses energy by emitting radiation such as alpha beta or gamma particle
What is alpha decay
Spontaneous emission of an alpha particle from a nucleus
What does alpha radiation consist of
Two protons and neutrons tightly bound together - a helium nucleus
What is beta decay
Spontaneous emission of a fast moving particle with the mass of an electron from a nucleus
What type of particles are produced by beta decay
Both negative and positive
What is gamma decay
Spontaneous emission of a high energy photon with no mass from the nucleus
Which type of radiation consists of helium-4
Alpha
Which type of decay can be stopped by a aluminium plate
Beta
What does beta radiation consist of
High energy protons or electrons
What can stop alpha radiation
Sheet of paper
What can stop gamma radiation
Lead
What are the 2 classifications of action / damage resulting from radiation of cells
Direct and indirect
What is indirect action / damage to tissue
Free radicals a produced by ionisation of water
What is direction action / damage to tissue
Ionisation of macromolecules such as DNA, enzymes and proteins
Which is the most destructive radiation
Alpha
What happens in beta minus decay
Neutron decays to a proton and releases an electron
What happens in beta plus decay
A proton decays to a neutron and releases a positron
What is a positron
A positively charged electron
How do free radicals work in indirect tissue damage
By transferring excess energy to other molecules and breaking chemical bonds
What can free radicals in indirect tissue damage produce
Hydrogen peroxide and hydroperoxyl radical which are both highly reactive and can cause biological damage
What are chromosomal effects from direct damage
Abnormal replication, cell death and the inability to pass on info
What is the linear energy transfer
How much energy is transferred per unit length
What are the two main categories of biological effects of radiation
Deterministic effects (tissue reactions)
Stochastic effects
What are deterministic effects - tissue reaction
Non cancer damaging effects that wiki definitely result from high dose radiation
What are stochastic effects cancer and genetic effects that may develop
What is the relationship between the severity of the effect and the threshold dose
Directionally - as one increases so does the other
What are the subdivisions of tissue reactions
Early and late
The ICRP uses which model
Liner non threshold model
What is absorbed dose
Energy deposited per unit mass as is measured in joules per kg
What symbol is used for absorbed dose
Gy - gray
True or false Gy is a SI unit
True
