kQ factors in modern external beam radiotherapy applications to update IAEA TRS-398

Short Name: RTNORM, Project Number: 16NRM03
Image of a patient lying in a medical scanner
Patient Receiving Medical ScanTreatment for Head Neck Cancer

New cancer treatments need new calibration calculations to ensure accuracy

Half of the 3.4 million Europeans diagnosed with cancer every year are treated with ionizing radiation. To ensure safety, radiation beams need to be calibrated. Correcting for differences between beam quality at the calibration laboratory and the hospital, a factor called kQ,Q0, is an important aspect of calibration.

The International Atomic Energy Agency’s protocol TRS-398, which governs radiotherapy dosimetry, uses kQ,Q0 values calculated in the 1990s. A major revision is underway to reflect advances in technology, new primary standards, and improved metrology and modelling.


This project  measured kQ,Q0 values using the latest ionization radiation technologies ensuring traceability to the SI, and also calculated kQ,Q0 using Monte Carlo modelling. The datasets will be compared to understand potential differences between measured and computed values. Validated values will be incorporated in the upcoming TRS-398 revision.

Through the revised protocol, European hospitals will have reliable correction factors for the latest ionizing radiation technologies, ensuring beams which treat 1.7 million citizens annually are accurately calibrated.


Project website
Other Participants
Associação do Instituto Superior Técnico para a Investigação e Desenvolvimento (Portugal)
Fundació Clínic per a la Recerca Biomèdica (Spain)
Katholieke Universiteit Leuven (Belgium)
Technische Hochschule Mittelhessen (Germany)