Hygiene and Occupational Medicine · MU Sofia

21. Principles of protection from external and internal exposure to ionizing radiation. Radiological protection of the population and personnel during medical procedures.

Covers the goals of radiation protection, namely preventing deterministic effects and reducing stochastic risk, followed by the three fundamental principles of justification, optimisation under ALARA and dose limitation. It then explains protection against external exposure with a shielding table by radiation type, and against internal exposure through preventive measures. The note closes with protection of patients and staff in medical practice, personnel monitoring, and public protection including waste management and radon.

Inside: 1 section · 1 labelled picture · 13 flashcards · 2 min

Topic 21 of 78 in the MU Sofia syllabus for Hygiene and Occupational Medicine (Medicine, Year 4). The free AceMed note covers it in 1 section, about 287 words (2 min of reading), with 13 flashcards.

In this note

  1. Principles of protection from external and internal exposure to ionizing radiation. Radiological protection of the population and personnel during medical procedures.

Principles of protection from external and internal exposure to ionizing radiation. Radiological protection of the population and personnel during medical procedures.

1. Goals of Radiation Protection

The purpose is to prevent deterministic effects (e.g., burns, ARS) and reduce the probability of stochastic effects (e.g., cancer, genetic mutations).

2. Fundamental Principles

  • Justification: A radiation practice should be used only when the benefits outweigh the risks. (Example: A diagnostic CT scan is justified only if it changes patient management.)
  • Optimization (ALARA Principle): Exposure must be kept As Low As Reasonably Achievable using proper shielding, monitoring, and work technique.
  • Dose Limitation: Individual radiation doses must not exceed legal limits, particularly for workers and the public.

3. Protection from External Exposure

External exposure comes from sources outside the body (e.g., X-ray devices, gamma sources).

Shielding Materials

  • Alpha: Paper, gloves
  • Beta: Plastic, acrylic, aluminum
  • Gamma / X-rays: Lead, concrete
  • Neutrons: Hydrogen-rich materials (water/polyethylene) + absorbers

4. Protection from Internal Exposure

Internal exposure results from inhalation, ingestion, skin absorption of radionuclides.

Preventive Measures

  • Use sealed radiation sources when possible
  • Lab ventilation and fume hoods for radioactive gases/aerosols
  • Strict hand hygiene and contamination control
  • Respiratory protection (masks/filters) in high-risk environments
  • Personal dosimetry and contamination monitoring

5. Radiation Protection in Medical Practice

For Patients

  • Choose examination with lowest adequate dose (e.g., ultrasound/MRI instead of CT when possible)
  • Use collimation (limit beam area)
  • Use pediatric dose adjustments
  • Avoid unnecessary repeat imaging

For Personnel (Healthcare Workers)

  1. 1. Stand behind protective screens
  2. 2. Wear lead aprons, thyroid collars, lead glasses
  3. 3. Use remote-controlled imaging when possible
  4. 4. Rotate staff to minimize exposure

Monitoring

  • Film badges and electronic personal dosimeters track cumulative exposure
  • Regular radiation safety training
  • Workplace dose mapping and area monitoring

6. Public Protection

  • Safe management of medical and industrial radioactive waste
  • Environmental monitoring around nuclear facilities
  • Regulation of radiation-emitting devices
  • Public education regarding radon reduction in homes

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