Radiation Protection in Nuclear Medicine

1. Protection of Pregnant Workers

It is generally accepted that the unborn child should be afforded the same protection level as a member of the general public. Therefore, a dose limit of 1 mSv should be applied once pregnancy is declared. Good operational procedures should ensure that the radiation doses received by staff working in nuclear medicine facilities are well below any occupational dose limits. Consequently, there is generally no need for a pregnant member of staff to change her duties based on the expected dose to the embryo or fetus.

However, it may be necessary to remove pregnant workers from laboratories where large quantities of radionuclides are prepared and administered or from nursing teams responsible for patients who have been treated with radionuclides. These workers could receive a dose to the embryo or fetus that is comparable with the public dose limit over the period of pregnancy.

Since all doses should be reduced whenever possible, some supervisors may consider it prudent to reassign pregnant staff to non-radiation duties, if feasible. Many nuclear medicine facility managers would also accept requests for reassignment based on reasons beyond radiation protection. Previous personal monitoring results can assist in guiding such decisions, noting that the dose to the fetus from external radiation is unlikely to exceed 25% of the personal dosimeter measurement.

2. Conditions for Young Persons

According to the Basic Safety Standards (BSS), no person under the age of 16 years is to be subjected to occupational exposure. Additionally, no person under the age of 18 years should be allowed to work in a controlled area unless they are supervised, and then only for the purpose of training.

3. Key Radiation Protection Measures

In nuclear medicine, various radiation protection strategies are applied to ensure the safety of workers and the public. These strategies include:

3.1 Shielding

Effective shielding is crucial in minimizing exposure to radiation. Depending on the type of radiation emitted by radionuclides used in nuclear medicine, different materials are used for shielding:

• Lead (Pb): Often used for shielding gamma radiation. It is effective at blocking high-energy photons.
• Concrete: Used for large-scale installations where thicker shielding is required.
• Glass and plastic: Used for shielding beta particles, which can be effectively stopped by light materials.

Shielding should be appropriately designed based on the type of radionuclide, the form of radiation, and the required protection level in specific areas (e.g., patient rooms, laboratories, or storage areas). Proper shielding ensures radiation does not escape the controlled area and minimizes exposure to workers.

3.2 Personal Protective Equipment (PPE)

PPE is essential to provide additional protection to workers handling radiopharmaceuticals or working in areas with radiation. Key PPE includes:

• Lead aprons: Worn by staff during patient injection or imaging procedures to protect from scatter radiation.
• Gloves: To protect hands from contamination and radioactive materials when preparing or administering radiopharmaceuticals.
• Thyroid shields: For additional protection from radioactive iodine and other isotopes.
• Safety goggles: Used to protect eyes from splashes or radiation.

3.3 Radiation Monitoring

Continuous radiation monitoring is necessary to ensure that exposure levels remain within safe limits. Key monitoring devices include:

• Personal dosimeters: Worn by workers to measure radiation exposure over time.
• Area monitors: Installed in critical locations to monitor ambient radiation levels.
• Handheld survey meters: Used for spot checks to assess radiation levels in specific areas.

Regular calibration of radiation monitoring equipment is essential to ensure accurate measurements and compliance with safety standards.

3.4 Emergency Procedures

In case of radiation spills or accidents, immediate action is necessary to limit exposure. The key emergency procedures include:

• Evacuate the area: Ensure that all individuals in the affected area leave the premises quickly and safely.
• Contain the spill: Use absorbent materials or containment trays to limit the spread of radioactive materials.
• Notify authorities: Alert the radiation safety officer (RSO) and local authorities immediately for further action.
• Decontamination: In case of skin contamination, the affected area should be thoroughly washed using proper procedures.

3.5 Safety Protocols for Different Areas

Specific areas within a nuclear medicine facility require tailored safety protocols:

• Radiopharmaceutical preparation areas: These should be equipped with fume hoods, proper shielding, and dedicated waste containers for radioactive material. Protective clothing and gloves must be worn at all times.
• Patient care areas: These should have radiation shields and clear signage indicating radioactive materials are present. Patients undergoing therapy should be monitored for radiation exposure and isolated from non-patient personnel.
• Storage areas: Radioactive sources should be stored in well-marked, secure, and ventilated rooms. Containers must be leak-proof and clearly labeled with the radionuclide information, activity, and associated risks.

4. Summary of Radiation Protection in Nuclear Medicine

The protection of workers in nuclear medicine involves a combination of justified practices, optimized protection measures, and strict adherence to regulatory standards. Measures such as shielding, PPE, radiation monitoring, and adherence to safety protocols for various work areas are essential in ensuring a safe working environment. By following these detailed procedures, radiation exposure can be minimized to acceptable levels, protecting the health of both workers and the public.