21. Sources of ionizing radiation. Occupational and medical exposure.

ionizing radiation

energy that is carried by any of several types of particles and rays given off by

• radioactive materials

• X-ray machines

• nuclear reactions

How does ionizing radiation occur as?

• Electromagnetic rays
  → Examples: X-rays, Gamma rays (γ)
  → Have no mass or charge, but carry energy that ionises atoms.

• Particles
  → Examples: Alpha (α) and Beta (β) particles
  → Have mass and/or charge and directly collide with atoms, causing ionisation.

What does source of ionizing radiation mean?

means any equipment (installation or material)

• which produces ionising radiation

What are the types of sources of radiation ?

Natural Sources

Man-made (Artificial) Sources

natural sources

• Cosmic rays

  • from outer space to the Earth

• Environmental radiation

  • from radioactive elements in soil and rocks, and buildings

  • e.g., uranium and radium

  • atmospheric gases- radon and thoron

• Internal radiation

  • from radioactive isotopes naturally present in our body tissues.

Man-made sources

• X-rays
  → Widely used in medical and dental fields for diagnosis and treatment.

• Radiopharmaceuticals
  → Used in diagnostics, radiotherapy, and research.
  → Includes radiolabeled monoclonal antibodies.

• Occupational Exposure
  → Affects workers handling radiation (e.g. medical staff, nuclear plant workers, pilots).

• Radioactive Fallout
  → From nuclear explosions/ accidents

  — releases radioactive particles into the atmosphere.

• Miscellaneous Sources
  → Everyday appliances emit minimal radiation

  • considered negligible.

Intake of Natural & Man-Made Radioactive Materials

• Inhalation
  → Main source of exposure; radon-220 and radon-222 gases.

• Oral Ingestion
  → From contaminated food and drinking water.

• Dermal Absorption
  → Minor route of exposure.

Types of Radiation Exposure

• External Exposure
  → Radiation from outside the body
  → Can affect whole body or a local area
  → Example: exposure to radioactive materials

• Internal Exposure
  → Radiation from within the body
  → Entry via inhalation, ingestion, skin absorption, or radiopharmaceuticals (RPh)
  → Can also be whole body or localized

Occupational exposure

• Only qualified and medically fit individuals may work with ionizing radiation sources

• Workers must undergo regular medical surveillance:
  → Before employment, during work, and upon leaving the job

• Prohibited from working with ionizing radiation:

  • Individuals under 18 years old

  • Pregnant or breastfeeding women (when working with open sources)

  • Persons with contraindicated medical conditions

medical exposure

• what to cover

• general

• rules

• background

medical exposure- General

• Widely used in diagnostics and treatment (mostly diagnostic)

• Exposure levels:

  • Increase with healthcare advancement (more procedures)

  • The average dose per procedure decreases with improved technology

• Must be justified: benefits vs potential radiation harm

medical exposure- Safety Rules & Protections

Röntgen machines may operate only with proper protective equipment:

• Fixed shields (e.g., encapsulated hoods)

• Door interlock systems (prevent use if the door is open)

• Lead aprons (especially for pregnant women), lead glasses

• Personal dosimeter worn on body:

  • Measures whole-body dose in mSv

  • Tracks monthly exposure

• X-ray dosimeters used for radiation monitoring

• Radiation protection supervisor ensures safety compliance

• Workers must follow local safety protocols and procedures

medical exposure- principles

• No exposure without prescription by a medical specialist

  • only x-ray and CT given by licensed medical doctor

  • clinically justified

• Specialists ensure patient protection and safety

  • responsible for minimising risks and maximising benefit

• Involvement of trained medical and paramedical personnel

  • ensures proper handling of equipment

  • redused dose and errors

• Source calibration, dosimetry, and quality control overseen by a qualified radiophysics expert

  • check for calibration, accuracy and safety

  • quality control

• Personnel training is mandatory

  • all staff properly trained

  • how to use protective measures

  • emergency procedures

  • understanding radiation risks