Why is quality control mandatory in radiotherapy?
Quality assurance (QA) in radiotherapy is a legal and clinical requirement in Portugal. Modern radiotherapy — whether using linear accelerators (LINACs), tomotherapy systems or proton equipment — involves high, highly conformal doses of ionising radiation. A 5% error in delivered dose can compromise tumour control or cause severe complications in adjacent healthy tissues. For this reason, medical physicists are responsible for implementing rigorous quality assurance programmes in compliance with national and international recommendations.
In Portugal, the regulatory framework is defined by the Directorate-General for Health (DGS) and Decree-Law No. 180/2002, which transposes Euratom Directive 97/43/EC into Portuguese law. This legislation establishes the legal basis for the radiological protection of patients exposed to ionising radiation for medical purposes, assigning the medical physicist a central role in ensuring that therapeutic doses are delivered with precision, safety and efficacy.
Daily QA — routine checks with detectors and in-vivo dosimetry
Daily quality control is the foundation of operational safety in any radiotherapy department. Before the first treatment of the day, the medical physicist or radiotherapy technician must verify a minimum set of parameters including dose constancy with the Daily QA™ 3 from Sun Nuclear, beam symmetry and flatness, laser and isocentre alignment, and in-vivo dosimetry using diode detectors or MOSFETs.
Annual QA — commissioning and audits
The annual QA programme and commissioning of new equipment requires complete beam characterisation, verification of mechanical parameters, and validation of dose planning algorithms. Equipment typically used includes reference ionisation chambers, water phantoms, anthropomorphic phantoms such as the ATOM® Phantom Family, and 2D detector arrays like the MapCHECK®3.
IMRT/VMAT QA — Sun Nuclear ArcCHECK, IC Profiler and SNC Patient
Verification of IMRT and VMAT plans is one of the most critical areas of radiotherapy quality control. Interphysix provides the complete Sun Nuclear portfolio:
- ArcCHECK® — 3D cylindrical array of 1386 diode detectors for VMAT arc verification;
- ArcCHECK®-MR — MR-compatible version for MR-Linac environments;
- IC PROFILER™ — planar ionisation chamber array for beam profile measurement;
- MapCHECK®3 — high-resolution diode detector array for 2D IMRT/VMAT verification.
The SNC Patient™ software integrates all these detectors in a unified analysis platform, enabling gamma analysis with configurable criteria (typically 3%/3mm or 2%/2mm).
Stereotactic QA (SRS/SBRT) — sub-millimetre precision
Stereotactic radiotherapy — SRS for intracranial targets and SBRT for extracranial tumours — demands the highest level of dosimetric and geometric precision. Sun Nuclear provides the SRS MapCHECK® with 1013 high-density detectors, MotionCHECK™3D for motion-managed SBRT, and WaterProof PROFILER™ for small-field commissioning.
Portuguese legislation — DGS and Decree-Law No. 180/2002
The legal framework for radiotherapy QA in Portugal includes Decree-Law No. 180/2002 (transposing Euratom Directive 97/43/EC), Ordinance No. 331/2009, DGS technical guidelines, and Euratom Directive 2013/59 (transposed by Decree-Law No. 108/2018). Compliance requires calibrated measurement equipment, written QA protocols and systematic recording of all results.
Interphysix — your technical partner in Portugal
Interphysix is the exclusive distributor of Sun Nuclear Corporation in Portugal. Our specialised team offers technical support, clinical training, installation, commissioning and ongoing assistance in developing radiotherapy QA programmes across leading hospitals and oncology centres in Portugal.
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Our team is available to assess the specific needs of your radiotherapy department and propose the most suitable QA solution.
Última actualização: 19/03/2026