Facility Design
The involvement of a medical physicist in the planning and design of a nuclear medicine facility is crucial. The facility's design must ensure safety, radiation protection, and minimize contamination risks while meeting the required standards for radiopharmaceutical use. Key factors to consider include:
- Safety of Sources: Ensuring radiation sources are safely stored and handled.
- Optimization of Protection: Implementing protection measures for staff and the public.
- Contamination Control: Preventing the uncontrolled spread of radioactive materials.
- Background Radiation: Maintaining low background radiation in critical areas.
- National Regulations: Meeting national standards for pharmaceutical work.
Location and General Layout
The location of the nuclear medicine facility within the hospital is not overly critical, but several factors need consideration:
- Accessibility: The facility should be easily accessible, especially for outpatients.
- Distance from High Radiation Sources: The facility should be placed away from high radiation areas, such as radiotherapy rooms or cyclotrons, to avoid interference with measuring equipment.
- Isolation Wards: Isolation wards for radionuclide therapy should be separated from the main nuclear medicine facility.
The general layout should allow separation between work and patient areas to reduce contamination risks. Rooms for the preparation of radiopharmaceuticals should be placed far from patient waiting and measurement areas. Additionally, transport of unsealed sources within the facility should be minimized.
The floor plan should be designed with low-activity areas near the entrance, and higher-activity areas situated further within the facility. For further details, the IAEA's Nuclear Medicine Resources Manual provides additional guidelines.
General Building Requirements
The design must cater to the specific type of work and radionuclides in use. Hazard categorization (low, medium, or high) will guide decisions about materials, ventilation, plumbing, and floor finishes. High-hazard rooms, especially those handling radioactive aerosols or gases, must be equipped with specialized ventilation systems such as fume hoods or laminar air flow cabinets.
Floor and workbench materials should be impermeable, washable, and resistant to chemical changes. In areas where contamination risks are high, furniture and equipment should be easily decontaminated. While hygiene is important in all areas, patient comfort should also be considered in waiting rooms.
Source Security and Storage
Security measures must be in place to prevent theft, loss, or unauthorized use of radioactive sources. Only authorized personnel should be allowed to order radionuclides, and the handling and storage processes should be clearly defined. Records of all sources must be kept, and the facility should always know the exact location and use of each source.
Accidental fires and their consequences must be carefully considered. Non-flammable materials should be used in construction, and the facility should liaise with local fire authorities to ensure appropriate firefighting equipment is available, particularly near storage areas for radioactive waste.
Structural Shielding
Structural shielding is a critical consideration in a busy nuclear medicine facility, especially when handling high radiation activities. Facilities like PET/CT require more extensive shielding due to the high energy of the radiation used. A qualified medical physicist should be consulted during the planning stage to perform necessary calculations for shielding and protective barriers.
Incorrect shielding design can be costly to correct, so expert consultation at the design stage is essential to ensure effective radiation protection while also considering the economic impact of the design.