Module 2 (Radiation Exposure Context) Flashcards
What are the two main categories of radiation sources?
Natural Sources (e.g., cosmic radiation, radon gas, gamma rays)
Man-Made Sources (e.g., medical imaging, industrial sources, nuclear events)
What are the five natural sources of radiation?
Cosmic Radiation (from space)
Soils and Rock (uranium, potassium, thorium)
Gamma Rays (natural & man-made)
The Human Body (potassium-40)
Radon and Thoron (radioactive gases from uranium decay)
How does cosmic radiation affect radiation exposure?
Originates from the Sun and outer space.
Interacts with Earth’s atmosphere to create secondary radiation.
Higher altitudes = Increased exposure (airplane passengers & pilots receive more).
What natural radioactive elements are found in soil and rock?
Uranium
Potassium-40
Thorium
These long-lived radionuclides have existed since Earth’s formation and contribute to background radiation.
What is the difference between x-rays and gamma rays?
X-rays: Man-made, produced in medical imaging.
Gamma rays: Natural & man-made, emitted from unstable atomic nuclei (e.g., radon, potassium-40, nuclear medicine).
How does the human body contain radioactive material?
The body contains potassium-40, a natural radionuclide.
A 70 kg person has 140g of potassium, with 0.018% being radioactive.
The body emits 6000 radioactive decays per second.
How does radon gas contribute to radiation exposure?
Radon-222 and Thoron (Radon-220) originate from uranium decay in soil and rock.
Accumulates in basements and poorly ventilated areas.
Decays into harmful isotopes (bismuth & polonium) that damage lung tissue, increasing the risk of lung cancer.
What are the three main man-made sources of radiation?
Medical Radiation (largest source, from x-rays, CT, nuclear medicine)
Industrial Sources (nuclear power plants, uranium mining, smoke detectors)
Nuclear Events (Chernobyl, Fukushima, Hiroshima, atomic testing)
Why is medical radiation the largest source of man-made exposure?
Increased use of medical imaging (X-rays, CT scans, nuclear medicine).
High radiation doses in certain procedures.
Public health concern due to cumulative radiation exposure.
What industrial sources contribute to radiation exposure?
Uranium mines
Nuclear power plants
Consumer products (e.g., smoke detectors with americium-241)
Historical sources (radium in watch dials, early medical treatments)
What nuclear events have contributed to radiation exposure?
Chernobyl (1986) – Power plant explosion, long-term contamination.
Fukushima (2011) – Tsunami-induced nuclear meltdown.
Hiroshima & Nagasaki (1945) – Atomic bombings, radiation sickness.
Marshall Islands nuclear testing (1946-1958) – Long-term environmental impact.
What are the two main types of ionizing radiation?
Ionizing Electromagnetic Radiation (X-rays, Gamma rays) and Particulate Ionizing Radiation (Alpha particles, Beta particles, Neutrons, Protons).
What is ionizing electromagnetic radiation?
High-energy radiation capable of removing electrons from atoms (ionization). Includes X-rays and Gamma rays. Used in medical imaging but can also cause biological damage.
What are examples of non-ionizing electromagnetic radiation?
UV light, Visible light, Infrared radiation, Microwaves, Radio waves. These do not have enough energy to ionize atoms.
What are the types of particulate ionizing radiation?
Alpha particles (from Uranium and Plutonium), Beta particles, Neutrons, Protons & Electrons. These particles are emitted during radioactive decay and have different penetration abilities.
What is Linear Energy Transfer (LET) and why is it important?
LET measures energy deposited in tissue by radiation. Low-LET radiation: X-rays and Gamma rays (sparsely ionizing, random interactions). High-LET radiation: Dense ionization, higher potential for biologic damage (e.g., alpha particles).
How does LET affect biological damage?
Higher LET = More energy deposited = More biological damage. Low-LET radiation (X-rays, Gamma rays): Less damage, more penetration. High-LET radiation (Alpha particles, Beta particles): More damage, less penetration.
What is the relationship between ionizing radiation and biological damage?
Ionizing radiation removes electrons, leading to cellular ionization. Can damage DNA and cell structures. Risk of biologic effects depends on LET and type of radiation exposure.
What are the key differences between X-rays and Gamma rays?
X-rays: Man-made (medical imaging). Gamma rays: Emitted from radioactive elements. Both are ionizing but differ in origin.
What are the three main classifications of radiation exposure?
Occupational Exposure, Medical Exposure, Public Exposure
What is Occupational Exposure?
Occupational exposure is radiation exposure incurred in the workplace by professionals using imaging equipment or radiation-emitting devices.
Examples include MRTs, Radiologists, surgeons, and nurses.
Who is affected by Occupational Exposure?
Radiation workers (MRTs), Radiologists, surgeons, nurses, and other healthcare providers exposed to radiation as part of their job.
What is Medical Exposure?
Medical exposure refers to radiation exposure received by patients during diagnostic or therapeutic medical procedures, justified based on risk vs. benefit.
What is Public Exposure?
Public exposure includes all radiation exposure not classified as medical or occupational, mainly from natural sources.
Which category contributes the most to radiation exposure within a population?
Public Exposure remains the highest source of radiation exposure within a population.
What factors influence the effects of radiation on the human body?
Dose (source of ionizing radiation), whole body vs. partial body exposure, age, gender, and size (BMI).
How are the effects of radiation exposure categorized?
Early effects: Manifest within hours to months after exposure. Late effects: May not appear for years, if at all.
What type of exposure causes early effects?
Large-dose, whole-body exposures (e.g., nuclear bombs, reactor accidents).
What is Acute Radiation Sickness (ARS)?
A collection of symptoms experienced after a high-dose, whole-body exposure to radiation.
Why do early effects cause public fear of radiation?
Because of widely known effects from nuclear bombings and reactor disasters.
What are somatic and genetic effects?
Somatic effects: Seen in the exposed individual. Genetic effects: Hypothetical effects on future generations (no conclusive evidence).
What is the significance of gonadal shielding in radiation protection?
It has largely been discontinued due to the lack of evidence supporting genetic effects from radiation exposure.
How do early effects relate to radiation dose?
Early effects are deterministic, meaning they occur above a known threshold and are directly related to the dose received.
Are early effects relevant to medical imaging?
No, early effects are only associated with large whole-body exposures, not medical imaging.
What are late effects of radiation?
Long-term impacts of low-dose radiation exposure that manifest months to years later.
What are examples of late effects?
Cancer (carcinogenesis), cataracts, possible genetic effects (though no conclusive evidence).
What is the most documented late effect of high-dose whole-body radiation exposure?
Carcinogenesis (cancer formation).
Is there conclusive evidence that low-dose radiation increases cancer risk?
No, there is no conclusive evidence that low LET ionizing radiation at low doses (<0.1 Gy or 100 mSv) increases malignancy risk.
What are some research areas related to low-dose radiation exposure?
Cancer induction, fetal damage from in utero exposure, genetic effects.
