ESTRO 2025 - Abstract Book

S2593

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

Conclusion: Reduced dose measurement uncertainty in electron beams can be achieved by using a Farmer chamber instead of a plane-parallel chamber. The deviation in dose measurement between the plane-parallel and Farmer chambers at all energies is smaller than the associated uncertainties and can be neglected. This allows direct use of the secondary standard Farmer chamber for all reference dosimetry tasks. By eliminating the need for a cross calibration, procedures are significantly simplified, reducing costs and the amount of equipment needed.

Keywords: Farmer chamber, Electrons, reference dosimetry

References: [1] Nederlandse Commissie voor Stralingsdosimetrie, Code of Practice for the Absorbed Dose Determination in High Energy Photon and Electron Beams, NCS, Delft (2012), https://doi.org/10.25030/ncs-018 [2] Muir BR, McEwen MR. Technical Note: On the use of Farmer ionization chambers for electron beam reference dosimetry. Med Phys. 2017. https://doi.org/10.1002/mp.12582 [3] Muir BR, Rogers DW. Monte Carlo calculations of electron beam quality conversion factors for several ion chamber types. Med Phys. 2014. https://doi.org/10.1118/1.4893915 [4] INTERNATIONAL ATOMIC ENERGY AGENCY, Absorbed Dose Determination in External Beam Radiotherapy, Technical Reports Series No. 398 (Rev. 1), IAEA, Vienna (2024), https://doi.org/10.61092/iaea.ve7q-y94k