QA & Dosimetry Systems
Radiation therapy quality assurance, beam calibration and patient-specific verification.
Every radiotherapy machine must be proven safe before it treats a patient — every day.
PTW Dosimetry is the global reference standard for radiation therapy quality assurance. Its instruments — ionisation chambers, electrometers, water phantoms and patient-specific QA arrays — are used in radiotherapy departments worldwide to verify machine output, characterise beam data and confirm that treatment plans are delivered as prescribed. In Africa, where radiotherapy departments are frequently inspected by national nuclear medicine regulatory authorities, a complete PTW QA programme is both a patient safety requirement and a regulatory prerequisite. Jos•Hansen supplies, commissions and supports the full PTW QA toolchain across East and Southern Africa.
Compliance
A functioning QA programme is not optional — it is a regulatory requirement for operating a licensed radiotherapy department. PTW systems meet IAEA, AAPM and IPEM standards and produce the documentation required for national nuclear medicine authority inspections.
Patient safety
Pre-treatment patient-specific QA with the OCTAVIUS 4D system measures the actual dose delivered by each IMRT or VMAT plan before the patient receives their first fraction — catching calculation or delivery errors that would otherwise go undetected.
Universality
One PTW toolchain covers every modality in the department: LINACs, CyberKnife, Radixact, Flexitron HDR — the same chambers, electrometer and phantom system validate beam output across all radiotherapy equipment.
Absolute dose calibration — the foundation every treatment plan is built on.
Reference dosimetry establishes the machine output in absolute units (cGy/MU) traceable to national primary standards. PTW's Farmer-type ionisation chambers and UNIDOS webline electrometer provide calibration to IAEA TRS-398 and AAPM TG-51 protocols with measurement uncertainty below 0.5%. This calibration is the anchor for every dose calculation in the treatment planning system — if it is wrong, every patient's prescription is wrong. Jos•Hansen manages annual re-calibration against SSDL/PSDL reference standards.
Beam characterisation with the MP3-M water phantom.
Commissioning a new radiotherapy machine — or re-commissioning after major service — requires 3D beam data acquisition: percentage depth dose curves, beam profiles, output factors and penumbra measurements across multiple energies and field sizes. The PTW MP3-M motorised water phantom, scanning software and ion chamber array acquire this data systematically and export it directly to major treatment planning systems. Jos•Hansen's medical physicists operate the full beam commissioning programme at every machine installation.
Patient-specific QA — verification before the first fraction is delivered.
IMRT and VMAT treatment plans concentrate high doses near critical structures using hundreds of small, modulated segments. The OCTAVIUS 4D system measures the actual delivered dose distribution and compares it to the treatment planning system's predicted dose using gamma analysis. Plans that fail the gamma criteria are identified and re-optimised before the patient is treated. This is the final safety check in the radiotherapy chain — and it is mandatory under IAEA and AAPM recommendations for all IMRT/VMAT programmes.
Technical specifications.
Reference dosimetry
PTW Farmer chamber + UNIDOS webline electrometer
Beam scanning
MP3-M motorised water phantom + OmniPro software
Patient-specific QA
OCTAVIUS 4D + 2D array detectors
Calibration standard
IAEA TRS-398 · AAPM TG-51 · IPEM Report 81
Traceability
PSDL / SSDL nationally traceable chain
Machine coverage
LINAC · CyberKnife · TomoTherapy · HDR · proton
Measurement uncertainty of PTW Farmer-type reference ionisation chambers — the precision anchor for all treatment dose calculations
Standard gamma analysis criteria for IMRT/VMAT patient-specific QA — the international benchmark for plan delivery verification
IAEA absorbed dose to water protocol — the single international standard governing reference dosimetry in all radiotherapy departments
Why QA.
Regulatory prerequisite
PTW QA programmes meet IAEA, AAPM and IPEM standards — producing the inspection documentation required by national nuclear medicine regulatory authorities.
Patient-specific verification
OCTAVIUS 4D catches IMRT/VMAT delivery errors before they reach the patient — a mandatory safety step under IAEA and AAPM recommendations.
Full-department coverage
One PTW toolchain validates every modality — the same reference chambers, electrometer and phantom system work across LINACs, CyberKnife, TomoTherapy and HDR.
Calibration and physics support
Jos•Hansen manages annual re-calibration against SSDL/PSDL standards, consumable supply (chambers, detectors) and physicist training programmes.
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