Overview
SIST EN ISO 28057:2021 – Clinical Dosimetry with Solid Thermoluminescence Detectors is a European standard developed by CEN, aligning with ISO 28057:2019. This standard sets out procedures, systems requirements, and applications for thermoluminescence dosimetry (TLD) in radiotherapy contexts, focusing on dose measurement for photon and electron radiations. It is particularly relevant for dosimetry using solid TL detectors such as rods, chips, and microcubes made of lithium fluoride (LiF:Mg,Ti or LiF:Mg,Cu,P) in either crystalline or polycrystalline form.
SIST EN ISO 28057:2021 establishes guidelines to ensure accurate and reliable dosimetry for clinical radiotherapy, supporting both patient safety and treatment efficacy. The standard excludes procedures for LiF powder-based TLDs due to their need for specialized methods.
Key Topics
- Probe Method for Dosimetry: The standard describes the use of the probe method, involving the arrangement of TL detectors (or sets of detectors, known as TL probes) in thin-walled PMMA casings. Placement is typically in water or tissue-equivalent phantoms, essential for simulating clinical scenarios.
- Detector Materials: Applies to solid TL detectors made from specified types of LiF with dopants (Mg, Ti or Mg, Cu, P), ensuring material consistency for dose measurement.
- Radiation Types and Energy Ranges:
- Photon Radiation: 20 keV to 50 MeV
- Electron Radiation: 4 MeV to 25 MeV
- Brachytherapy Applications: Focused on photon-emitting radionuclides.
- Measurement Procedures: Rules for pre-irradiation treatment (annealing), detector positioning, calibration, reading processes, and required correction factors are included to safeguard result validity.
- System Requirements: Addresses completeness and operational requirements for TLD systems, including hardware, software, calibration devices, and performance checks.
- Quality Assurance: Emphasizes repeatability, uncertainty management, and acceptance testing to maintain clinical dosimetry standards.
Applications
This standard finds essential use in multiple clinical and research settings, including:
- External Beam Radiotherapy: Ensuring precise dose measurement in high-energy clinical accelerators by complementing ionization chamber dosimetry.
- Brachytherapy: Quantifying dose from photon-emitting sources in tissue or phantom settings.
- Dose Distribution Studies: Mapping absorbed doses in high-gradient regions (e.g., small stereotactic fields) and large-volume phantoms for treatment planning and verification.
- Quality Assurance Programs: Postal dose intercomparison and routine performance checks to assure compliance with international radiotherapy protocols.
- Detector System Development: Used by manufacturers for the design and validation of TLD instrumentation and probe assemblies in compliance with stringent clinical requirements.
Related Standards
Standards frequently referenced or used alongside SIST EN ISO 28057:2021 include:
- IEC 60601-1 – Safety requirements for electromedical equipment
- IEC 61000 series – Electromagnetic compatibility testing procedures
- IEC 61187 – Documentation for measuring equipment
- ICRU Reports – Dosimetry protocols and definitions
- ISO 28057:2019 – The international standard on which this European adoption is based
By following SIST EN ISO 28057:2021, clinical teams and equipment manufacturers can achieve internationally recognized best practices in dosimetry with solid thermoluminescence detectors, enhancing the accuracy and reliability of radiation therapy dosimetry. This standard serves as a critical reference point in medical physics, radiological protection, and radiation therapy quality assurance.