Radiation Biology Basics Quiz

Radiation Sources and Hazards

• This is a presentation on radiation sources and hazards
• The presentation includes a timeline for a module on fundamentals of radiation and radiation safety (2024-2025) with lecture dates and topics.
• Module learning objectives include demonstrating principles of radiation protection in diagnostic imaging, recognizing the importance of ionising radiation regulations and radiographers' responsibility for implementation
• Today's learning outcomes include understanding two different classifications of radiation, developing a basic understanding of radiation biology, introducing a range of radiation dose measures, discussing the effects of exposure to ionizing radiation and gaining an understanding of radiation risks and their magnitude.
• The presentation includes a song of the week, "It's the end of the world as we know it" by R.E.M.

Types of Radiation

• Two main types of radiation: non-ionising and ionising
• Non-ionising radiation has low frequency and low energy, causing heating effects. Examples include radio waves, microwaves, infrared, visible light, and UV. Skin burns from UV (sunburn) are an example of a heating effect.
• Ionising radiation has high frequency and high energy. Examples include X-rays and gamma rays, and the particles alpha, neutrons, protons, and electrons. This type of radiation poses a health risk because it can damage tissue and DNA
• Even very low doses of ionising radiation can cause significant and lasting damage.

Types of Ionising Radiation

• Particulate radiation includes alpha particles, neutrons, protons, and electrons
• Photon radiation includes gamma rays and X-rays

Background Radiation

• A pie chart shows radiation sources and per capita UK dose (2010) by percentage.
• Radon and Thoron, Medical, Terrestrial Gamma, and Cosmic are the main contributors
• Intake of radionuclides, discharge, occupation, and weapons fallout each contribute a small percentage.
• Background radiation varies geographically.

Radon Gas

• Radon is a naturally occurring radioactive gas, originating from the decay of uranium in rocks and soil.
• Radon gas enters homes through cracks in foundations, floor and wall gaps and enters the water supply, causing exposure to all inhabitants who breathe it in every day.
• Radon levels in England and Wales are displayed on a map showing geographic variations

Cosmic Radiation

• Cosmic radiation consists of very energetic charged particles travelling through space.
• When these particles enter the Earth's atmosphere, they collide with atoms producing secondary radiation.
• Background cosmic radiation levels are measured at ground level. The annual dose varies with altitude.

Internal Exposure from Food, Drink, Tobacco

• Natural radionuclides are taken up by plants and enter the food chain
• People are exposed to varying amounts of radiation through food, drink and tobacco.

Terrestrial Gamma Radiation

• Uranium, thorium, and potassium-40 continuously emit gamma rays by decaying, producing significant gamma radiation from soil and building materials.
• This is a continuous source of background radiation for everyone.

Medical Radiation

• Medical procedures, such as CT scans, are a major source of man-made radiation exposure.
• Medical imaging procedures such as, conventional, interventional , angiography (x-ray procedures) are also significant sources of exposure

Other Sources

• Other sources of radiation exposure include industrial, and occupational exposures (nuclear, defence, medical, industry and aircrew), fallout, disposals (industry and universities).

Radiobiology

• Radiobiology examines the effects of radiation on living organisms, including cellular processes, damage and repair mechanisms and how radiation can cause damage leading to significant effects like cancer.
• An image shows a cell's internal structure.
• Information about DNA structure is detailed here, including how ionising radiation causes cellular damage
• Ionising radiation's impact on DNA is examined and discussed in terms of double strand breaks being more harmful than single strand breaks. Direct and indirect effects are highlighted

Cellular Damage from Ionising Radiation

• Ionising radiation absorption causes chemical changes instantly in living tissues
• This leads to molecular damage.
• The effects may not appear for a long period, taking hours to decades to see the damage

Indirect Effects from Radiation

• Ionisation of water produces hydroxyl radicals that can diffuse and damage DNA

X-Ray Photons

• X-ray photons cause excitations and heat generation. Interactions cause excitations, generating heat and also generate ions and free radicals. Direct and indirect actions of radiation lead to DNA damage, cell death, and potential late effects such as cancer, inherited effects, radiation sickness, and fetal developmental effects.

Factors Affecting Degree of Radiation Damage

• The severity of radiation damage is influenced by several factors, including absorbed dose, genetic susceptibility, cell/tissue type, age of cells, dose rate.

Radiation Dose Metrics

• Important metrics for understanding radiation dose, including absorbed dose, equivalent dose and effective dose
• Absorbed dose is energy deposited in a material, equivalent dose accounts for radiation type and effective dose considers tissue sensitivity

Absorbed Dose

• Absorbed dose measures energy deposited per unit mass in a material
• The SI unit for absorbed dose is the Gray (Gy) and is useful for Radiography where doses are generally measured in mGy or µGy

Equivalent Dose

• Equivalent dose takes into account the varying biological effects of different types of radiation.
• It is given in Sieverts (Sv)
• the Linear Energy Transfer (LET) is used, enabling a measurement of rate at which radiation energy transfers to a medium per unit length, enabling a quantification of radiation damage severity

Effective Dose

• Effective dose accounts for the varying sensitivities of different tissues to radiation.
• It is the equivalent dose multiplied by tissue weighting factors
• The unit for effective dose is the Sievert (Sv)

Typical Effective Doses in the UK

• A table listing different types of scans and their corresponding annual effective dose.

Risk in Context

• A table displaying the risks of death for common activities.

Stochastic and Deterministic Effects

• Stochastic effects, such as mutations, have no threshold and increase in probability with dose.
• Deterministic effects, such as skin burns, occur above a particular dose threshold, and their severity increases with increasing dose.
• The impact of radiation exposure is presented in ways that help to contextualize the risks relating to them, helping give them more meaning

Late Effects

• Late effects of radiation exposure may manifest after several months, even years. It is possible effects will only be seen after cumulative doses are received over a long period.
• Various examples of the types of late effects, including cataracts, skin damage, and impaired fertility, are provided, with threshold dose values for each

Acute Radiation Syndrome (ARS)

• ARS is a serious syndrome resulting from high-dose radiation exposure throughout the body.
• The presentation features an illustrative diagram showing the progression of ARS, comprising stages such as:
• Early symptoms (prodromal phase)
• A latent period where symptoms are less obvious
• Full-blown illness,
• Recovery/death.
• Information about a historical case of ARS (Alexander Litvinenko) is also featured in the presentation.

Practical Dose Measurement

• Entrance surface dose (ESD) measures radiation dose at the patient's entry point.
• Dose area product (DAP) multiplies radiation dose by the field area on patients, giving a measure of total dose to the patient.
• They are used in projective and fluoroscopy radiography.

Additional Notes

• The presentation likely uses visuals, such as images and graphs, to illustrate concepts and data, which are not present in the text data.
• The presentation notes include information about the different types of damage that radiation can do and the sources and types of radiation encountered.
• Presentations include an overview of Radiation safety, radiobiology and radiation risks.

Test your knowledge on the fundamentals of radiation biology, including the sources of radiation dose, effects of exposure, and safety measures. This quiz covers key topics related to ionizing radiation and its implications in medical contexts. Prepare to explore essential concepts and classifications within the field of radiation exposure.