Makindo Medical Notes

Overview of Radiation Exposure

Radiation exposure can come from natural sources, such as radon gas, cosmic rays, and naturally occurring radioactive materials, or from human-made sources, such as medical procedures, nuclear power plants, and radiation therapy. While radiation has beneficial uses, particularly in medicine, excessive or uncontrolled exposure can cause significant harm to human health.

Types of Radiation

• Ionizing Radiation:
  • Includes X-rays, gamma rays, alpha particles, beta particles, and neutrons.
  • Has enough energy to ionize atoms, leading to molecular changes that can damage biological tissues.
• Non-ionizing Radiation:
  • Includes ultraviolet (UV) radiation, visible light, infrared radiation, microwaves, and radiofrequency radiation.
  • Generally considered less harmful than ionizing radiation, but excessive exposure can still cause health problems (e.g., UV radiation leading to skin cancer).

Biological Effects of Ionizing Radiation

• Cellular Damage:
  • Ionizing radiation can directly damage DNA or produce reactive oxygen species (ROS) that indirectly damage DNA and other cellular components.
  • Damage can result in mutations, cell death, or malignant transformation.
• Deterministic Effects (dose-dependent):
  • Severity increases with dose.
  • Includes radiation burns, radiation sickness, and organ failure.
  • Examples: Skin erythema, hair loss, cataracts, and acute radiation syndrome (ARS).
• Stochastic Effects (probability-based):
  • Probability increases with dose, but severity is independent of dose.
  • Includes cancer and genetic mutations.
  • Examples: Leukaemia, thyroid cancer, lung cancer, and other solid tumours.

Acute Radiation Syndrome (ARS)

• ARS occurs after a high dose of ionizing radiation over a short period:
  • Hematopoietic Syndrome:
    • Occurs at doses of 1-10 Gy.
    • Damage to bone marrow leads to decreased production of blood cells, resulting in anaemia, infections, and bleeding.
  • Gastrointestinal Syndrome:
    • Occurs at doses of 10-20 Gy.
    • Damage to the lining of the gastrointestinal tract causes nausea, vomiting, diarrhoea, and severe dehydration.
  • Cerebrovascular Syndrome:
    • Occurs at doses above 20 Gy.
    • Severe damage to the central nervous system leads to neurological symptoms, loss of consciousness, and death within hours to days.

Long-term Effects of Radiation Exposure

• Cancer:
  • Increased risk of various cancers, including leukaemia, thyroid cancer, breast cancer, lung cancer, and other solid tumours.
  • Latent period can range from years to decades after exposure.
• Genetic Effects:
  • Mutations in germ cells can be passed on to offspring, potentially causing hereditary diseases and congenital abnormalities.
• Cardiovascular Diseases:
  • Increased risk of heart disease and stroke due to radiation-induced damage to blood vessels and heart tissue.
• Chronic Radiation Syndrome:
  • Long-term exposure to lower doses of radiation can lead to chronic health issues, including persistent fatigue, memory loss, and immune system dysfunction.

Protection and Mitigation Strategies

• Time:
  • Minimize the time spent near radiation sources to reduce exposure.
• Distance:
  • Increase the distance from radiation sources to lower exposure levels.
• Shielding:
  • Use appropriate shielding materials (e.g., lead aprons, barriers) to block or reduce radiation exposure.
• Personal Protective Equipment (PPE):
  • Wear protective clothing, gloves, and respiratory protection when handling radioactive materials.
• Radiation Monitoring:
  • Use dosimeters and other monitoring devices to track radiation exposure levels.
• Regulations and Guidelines:
  • Follow safety standards and guidelines set by regulatory agencies, such as the International Commission on Radiological Protection (ICRP) and the National Council on Radiation Protection and Measurements (NCRP).

Summary

Radiation exposure can pose significant health risks, particularly from ionizing radiation, which can damage DNA and cellular structures. The effects range from acute conditions like radiation sickness to long-term consequences such as cancer and genetic mutations. Understanding the types, sources, and biological effects of radiation, along with implementing protective measures, is essential for minimizing harm and ensuring safety in environments where radiation exposure is possible.

Health Exposure

Revisions

• Last updated 02/08/2018