Introduction and Radiation Review Flashcards
Angiography
- The radiographic visualisation of blood vessels after injection of a radio opaque contrast
- Help people who have blockages to the heart by inserting a permanent stent to hold the blood vessel open
May be
- Diagnostic
- Interventional
Radiation Protection (ICRP)
- Legislation and regulations are guided by recommendations from the International Commission on Radiological Protection
- Give the ‘official’ scientific view of the effects of radiation on people and so laws are written around their content
Radiation Protection (ARPANSA)
- Australian Radiation Protection and Nuclear Safety Authority
- Most of the QLD regulations are based on the ARPANSA regulations and codes
Deterministic Effect
- Most organs/tissues are unaffected by the loss of even a large number of cells
- When the number lost becomes large enough there is observable damage or loss of function
- Probability of causing observable damage or loss of function will be zero at small doses but rise rapidly (to 100%) above threshold dose
- Above the threshold, the severity of the damage will also increase with dose
Stochastic (Random) Effects
- As a result of exposure to IR, a cell is modified but still left viable and able to divide
There is a period in which:
- The probability that the effect will occur increases with dose
- The severity is not affected by the magnitude of the dose
- Examples include the induction of cancer and genetic effects
Recommendations for limiting exposure to IR are designed to:
- Prevent deterministic effects
- Keep the probability of stochastic effects from exceeding an acceptable level
Isotope
Nuclides with the same Z but different A
Same number of Protons but different number of Neutrons
Alpha Decay
Emission of a He particle from the nucleus
Beta Decay
Emission of an anti-neutrino and the conversion of a neutron to a proton
Positron Decay
Emission of a neutrino and the conversion of a proton to a neutron
Gamma Rays
- Emitted following nuclear decays due to changes in nucleon configuration
- A nucleus in an unstable, high energy state can decay to a lower energy state
- Excess energy is emitted
X-Rays
- Emitted following a change in the state of the atom (e.g., in particular the electron structure)
- Usually following ionisation, when an outer electron may fill the vacancy, the excess energy is emitted as an X-ray
Photon Interactions with Matter
- Photoelectric Effect
- Compton Scattering
- Pair Production
- Coherent Scattering
- Photonuclear Disintegration
Energy Loss Processes - Photons
- Photons penetrating matter will be attenuated via the 3 interaction processes
Intensity - Mew
- Is difficult to calculate so known features are obtained from experimental measurements
- Increases rapidly with atomic number
- Decreases rapidly with photon energy