Establishing Traceability for Radiotherapy Dose Calibration In Ukraine
Abstract
Purpose
Amid ongoing war, Ukraine continues to maintain and modernize radiation therapy (RT) services. Between 2023 and 2025, 24 linacs were installed to replace aging, non-rechargeable cobalt units. While linacs offer clinical advantages, they require stringent dosimetric control to ensure dose accuracy and stability. Even prior to these installations, Ukraine faced major challenges in dose monitoring and calibration due to the ostensible absence of a National Secondary Standard Dosimetry Laboratory (SSDL). This work describes foundational work to establish interim international traceability of absorbed dose measurements as a critical step toward developing a national SSDL in Ukraine.
Methods
An international collaborative team of physicists from medical and academic institutions was formed under the guidance of the National Physical Laboratory (NPL, UK), with support from the Help Ukraine Group. In the initial phase, cross-calibration measurements were performed using an ionization chamber calibrated at NPL. Four ionization chambers in Ukraine, with absorbed dose to water calibration coefficients (Ndw) certified in 2020-2021, and one ionization chamber calibrated in 2025 at ARPANSA, Australia were included. An Elekta Versa HD linac provided the irradiation source. Beam quality (TPR20/10) was measured for the selected photon energy to verify agreement with nominal values.
Results
Cross-calibration results demonstrated excellent agreement between measured and certificate Ndw values. Percentage differences ranged from 0.04% to 0.5%, remaining well below the stated uncertainties of the calibration certificates (0.9-2.2%). In parallel, collaborative links were established between scientific and clinical institutions in Ukraine, supported by international experts. A proposal for establishing a dosimetry laboratory within an institute of the National Academy of Sciences of Ukraine (NASU) was developed.
Conclusion
Our work provides evidence that international collaboration can support accurate and traceable dosimetry even during war crisis. Decisive initial steps have been made to safeguard the quality, safety, and sustainability of radiation therapy in Ukraine.