Revision of Semester 1 Key Terms and Lab Safety

Key Definitions in Radiopharmacy and Radiation Safety

• ALARA (As Low As Reasonably Achievable): This is the guiding principle stating that all occupational and patient radiation exposure must be kept as low as is reasonably achievable while still ensuring the required procedure is completed safely and effectively.

• Radiation Safety: A method implemented to protect occupational workers and the general public from the harmful biological effects of radiation.

• Aseptic Technique: A series of specific practices used to prevent contamination by harmful bacteria, viruses, or other microorganisms during the preparation of radiopharmaceutical products.

• Pathogen: An organism that causes disease to its host.

• Background Radiation: Radiation that is naturally present in the environment and is unrelated to the introduction of specific radioactive sources.

• Contamination: The unintended presence of radioactive material in any location where it is not desired, such as on personnel, equipment, or work surfaces.

• Decontamination: The process utilized to safely remove radioactive contamination from an object or area, including people, equipment, or workstations.

• Assay: A procedure used to measure or determine the specific amount of radioactivity in a sample, usually measured in units of $\text{MBq}$.

• Dose Calibrator: An ionization chamber used to measure the activity of radioactive materials prior to their administration or preparation.

• Half-life ($T_{1/2}$): The duration of time required for half of the radioactive atoms of a specific radionuclide to decay away.

• Generator Elution: The process of collecting sodium pertechnetate ($Tc-99m$) from a technetium generator.

• Molybdenum Breakthrough: A critical quality control procedure performed to ensure that $Mo-99$ contamination in the eluate remains within acceptable limits.

• Shielding: The use of absorbing material to attenuate ionizing radiation.

• Survey Meter: Hand-held instruments used for measuring ionizing radiation to check for contamination.

ALARA Principles and Exposure Reduction Methods

Radiation safety is predicated on the ALARA principle. Effective radiation safety relies on planning ahead, organization, and the application of safe working practices rather than rushing through procedures.

Time

• The goal is to decrease time to reduce the total dose received.

• Practical exercises are designed to develop skills for radiopharmacy activities so tasks can be completed efficiently, minimizing exposure length.

• Prepare all necessary equipment before starting a procedure and before un-shielding any radioactive source.

• Work efficiently without compromising safety or aseptic technique.

Distance

• Inverse Square Law: Doubling the distance from a radioactive source reduces the dose received to one quarter ($1/4$).

• Increase distance from the source whenever practical.

• Stand back while eluting the generator.

• Use syringes that have $2 \times$ the intended total volume when possible.

• Handle radioactive materials by grasping the area of the syringe furthest from the radioactive solution.

• Utilize tongs where appropriate.

• Use lead syringe holders when transporting radioactive doses.

Shielding

• Laboratory design includes extensive shielding, supplemented by additional shielding during practical tasks.

• Always perform work behind shielded L-blocks.

• Use vial shields, syringe shields, and shielded sharps containers whenever handling or storing radioactive material.

• Radioactive material must never be carried around unshielded.

Critical Questions Before Exposure

• What can I do to minimize my own or others' radiation dose?

• What can I use to minimize my own or others' radiation dose?

Radiation Hygiene and Personal Contamination Protocols

Because radiation is invisible, strict work practices are required to prevent spread.

Workstation Hygiene

• Line work areas behind L-blocks with plastic-backed absorbent paper (known as "blueys") to minimize small spills.

• If a small spill occurs, fold the paper, remove it, and dispose of it in appropriately shielded containers (do not use sharps bins).

• Change blueys frequently between activities to remove inadvertent contamination.

• Contaminated equipment should be removed from service and stored in shielded areas until it has decayed to background levels.

Management of Personal Contamination

• If contamination or a spill occurs, notify the tutor immediately. Do not attempt independent management.

• Glove Contamination:

  • Inform the lab tutor.

  • Remove gloves carefully.

  • Place contaminated gloves in a plastic waste bag; label with the isotope and date.

  • Store in a shielded waste cupboard for a minimum of $10$ half-lives until decayed to background level.

  • Wash hands thoroughly and check them with a survey meter.

• Clothing or Skin Contamination:

  • Notify the tutor immediately and remove clothing carefully.

  • Bag, label, and store clothing in a shielded cupboard for decay.

  • Wash affected skin with soap and water without rubbing so vigorously that the skin breaks.

  • Use a survey meter to monitor for residual activity.

  • For stubborn skin contamination, use a detergent or complexing agent. Tight disposable gloves may be worn for a couple of hours to encourage perspiration to help lift the contamination.

• Routine Monitoring:

  • Change gloves frequently, especially after handling radioactive materials.

  • Do not leave the station until the tutor has checked both the station and the student's hands with a survey meter.

Management of Radioactive Spills

Small Spills (e.g., on a bench or behind L-block)

• Notify the tutor immediately and prevent the spread of material.

• Change blueys and absorb the liquid using paper towels or blueys.

• Technique: Work from the outside of the contaminated area towards the center.

• Dispose of materials into the radioactive waste container, labeled with the radioisotope and date.

• Monitor with a survey meter and repeat cleaning until levels are acceptable for work.

Large Spills (e.g., on the floor)

• Stop work and inform the tutor or the Radiation Safety Officer (RSO) immediately.

• Cordon off the area to prevent entry.

• Gather equipment from the decontamination kit in the Hotlab.

• Ensure the person performing decontamination wears full PPE: gown, gloves, and shoe coverings.

• Check oneself for contamination using a survey meter.

• Contain liquid by covering the area with plastic-backed absorbent paper towels.

• Decontaminate using the outside-to-inside technique.

• Dispose of all items in labeled plastic bags and store behind lead shielding.

• Complete an incident report.

• All persons at risk must be checked with a survey meter and undergo decontamination if needed.

Radioactive and Non-Radioactive Waste Disposal

All radioactive waste must be labeled and stored in a shielded area for a minimum of $10$ half-lives before final disposal. The following classifications apply:

• Radioactive sharps, syringes, and swabs: Dispose of in a shielded sharps container.

• Non-radioactive sharps: Dispose of in a standard sharps container.

• Radioactive gloves, blueys, and paper towels: Dispose of in a radioactive waste container or plastic bag.

• Radioactive vials: Dispose of in a shielded sharps container.

• General waste: Dispose of in general under-bench waste bins.

Sharps Safety and Management of Needle-Stick Injuries

Sharps injuries carry both biological and radiation safety risks.

General Sharps Safety

• Dispose of all sharps immediately after use into approved containers.

• Use a needle recapper if re-sheathing is required.

• Never pass sharps directly between people; the user is responsible for safe disposal.

• Sharps containers should be near the point of use; if not, carry the sharp in a container like a kidney tray or shielded holder.

Radiopharmacy Specifics

• In Nuclear Medicine, it is necessary to re-sheath needles after drawing radioactive materials to prevent workstation and dose calibrator contamination.

• Needles must be safely and aseptically re-sheathed before air bubble removal and before measurement in the dose calibrator.

• Change the needle to a new sterile needle of appropriate gauge before patient administration.

Needle-Stick Injury Protocol

1. Notify the tutor immediately.

2. Remove gloves.

3. Wash the wound thoroughly with soap and water.

4. Apply first aid.

5. Complete required incident reporting.

Aseptic Technique and Standard Precautions

Standard (Universal) Precautions Model

• All blood and body substances (human or animal) are assumed to be potential sources of infection and are treated as infected with pathogens, regardless of perceived risk.

• Protective clothing, safe sharps disposal, spill management, and basic hygiene are used to minimize exposure via percutaneous injury or mucous membrane contact.

• Practices include swabbing vials, correct packet opening, and proper handling of needles, syringes, and blood products.

Professional Practice and Risk Management

• Working aseptically is a learned skill that improves with practice.

• Use the "risk vs benefit" model if a breach of technique is suspected.

• When in doubt, take action: ask the tutor, swab the item again, or assume contamination has occurred and replace the items (e.g., needles and syringes).