A newly constructed proton therapy centre represents a major facility in the field of radiation medicine, with its core mission being the treatment of cancer using proton beams. Consequently, radiation protection is a critical consideration throughout the design and construction phases. The configuration of radiation protection products directly affects the safety of patients, personnel, and the environment. The following are the principal categories of radiation protection products required in a proton therapy centre.
1. Radiation Shielding Materials
Radiation shielding materials are an indispensable component of a proton therapy centre. Their primary function is to attenuate and absorb radiation generated by proton beams, thereby preventing radiation leakage. Commonly used shielding materials include:
- Lead Sheet / Lead Brick: Lead is the conventional material of choice for shielding X-rays and gamma radiation, possessing strong radiation attenuation properties.
- Steel: In certain high-energy proton therapy systems, steel is used as a supplementary shielding material.
- Concrete: Used for structural shielding of walls and building elements, particularly in areas requiring large-surface-area shielding.
2. Radiation Monitoring Equipment
To ensure radiological safety for both the environment and personnel, a proton therapy centre must be equipped with a variety of radiation monitoring instrumentation for routine checking of radiation dose levels and early detection of potential radiation leakage.
- Radiation Detectors: Including proportional counters, scintillation detectors, etc., for real-time monitoring of radiation dose levels during treatment delivery.
- Personal Dosimeter (Wearable Dosimeter): Devices worn by personnel during proton therapy operations to continuously record individual radiation dose and ensure regulatory dose limits are not exceeded.
- Environmental Radiation Monitoring System: A network of sensors deployed across different zones to monitor ambient radiation levels in real time, ensuring compliance with environmental dose constraints.
3. Access Control and Shielding Doors
Between treatment areas and non-treatment areas of the proton therapy centre, dedicated radiation shielding doors and safety access control systems must be installed. These doors provide high-strength radiation shielding, preventing radiation leakage into non-treatment zones during beam delivery.
- Radiation Shielding Doors: Typically constructed from a combination of steel and lead sheet, capable of effectively attenuating radiation produced by proton beams.
- Safety Access Control System: Ensures that radiation within the treatment area does not leak outward and prevents unauthorized entry into high-radiation areas.
4. Radiation Protective Apparel
To protect personnel and patients from radiation exposure, a proton therapy centre must be equipped with professional radiation protective apparel, particularly for personnel engaged in equipment maintenance, commissioning, or treatment-related operations.
- Lead Apron: The most common protective garment, effectively shielding against X-rays and low-energy proton radiation; routinely worn by personnel operating in high-radiation zones.
- Lead Skirt and Lead Gloves: Primarily worn during treatment procedures when personnel may be in proximity to radiation sources, preventing bodily radiation injury.
- Radiation Protective Eyewear: To protect the eyes from radiation exposure, personnel conducting maintenance within the treatment area must wear radiation protective glasses.
5. Proton Beam Therapy Equipment
The proton therapy machine itself is also a key element of radiation protection, particularly with regard to the generation and focusing of high-energy proton beams. The design of the treatment equipment must incorporate precise radiation control and shielding considerations:
- Proton Beam Accelerator: The core device for treatment delivery; its design and operation must strictly comply with radiation protection standards to prevent radiation leakage.
- Beam Transport Line / Treatment Nozzle: The therapeutic proton beam is engineered to ensure precise focusing onto the tumour site while minimizing radiation exposure to surrounding healthy tissue.
6. Air Purification and Exhaust Ventilation Systems
During proton therapy, certain amounts of radioactive gases or secondary radiation may be generated; therefore, an air purification system forms part of the overall radiation protection scheme. The system includes:
- Radioactive Gas Adsorption Unit: Effectively filters and adsorbs radioactive gases, preventing environmental contamination.
- Ventilation and Airflow System: Ensures adequate air exchange within the treatment room, preventing the dispersion of airborne radioactive substances from high-radiation areas to other zones.
7. Radiation Shielding Viewing Windows
To ensure personnel safety while providing adequate visual observation of the treatment area, a proton therapy centre must be equipped with radiation shielding viewing windows in the treatment enclosure. These windows typically use high-quality radiation-shielding glass or lead-glass panels, ensuring that personnel monitoring the treatment process from outside are not exposed to radiation.
8. Personnel Training and Safety Management System
In addition to physical protection infrastructure, personnel training and safety management are of paramount importance. A proton therapy centre must provide regular radiation protection training for all staff to ensure proficiency in radiation safety operating procedures. Furthermore, a comprehensive radiation safety management system must be established, with periodic review and updating of protective measures.
Radiation protection measures at a newly constructed proton therapy centre are designed not only to ensure patient treatment safety but also to safeguard personnel and the surrounding environment. Through the appropriate configuration of shielding materials, radiation monitoring equipment, safety access controls, professional protective apparel, and other radiation protection products, radiation levels can be effectively controlled, ensuring the safety and manageability of the entire proton therapy process.