Entwicklung & Validierung eines standardisierten Qualitätssicherungsprozesses für strahlenbiologische Experimente mit einem Referenzröntgenstrahler (YXLON Maxishot)

Abstract

Background
Heavy ion therapy is an innovative form of radiation treatment that is characterized by the characteristic Bragg peak to spare healthy tissue. Radiobiological experiments are essential to further optimize the therapeutic efficacy. Since heavy ion therapy usually involves a horizontal irradiation geometry, there are special requirements for the positioning of the cell samples. To ensure the comparability of experimental results, reference irradiations are carried out with X-rays in identical geometry
Methodology
A QA process was developed for the standardization and quality assurance of these reference irradiations, which integrates 3D-printed phantoms made of ABS (⍴ = 1.030 g/cm³). These were produced using FDM technology and allow the precise positioning of various ionization chambers in the radiation field of the YXLON Maxishot reference source. In addition, CNC-manufactured side scatter phantoms made of PE (⍴ = 0.96 g/cm³) were used to systematically investigate geometry-dependent scattering effects. In addition, different ionization chambers and calibration procedures were validated with regard to their influence on dosimetry
Results 
The phantoms developed enabled highly precise and reproducible positioning of the detectors. The deviation of the measured dose values from the theoretical reference values was a maximum of 2,12 %, which confirms the high accuracy of the developed QA setup. The side-scatter measurements showed significant lateral scattering effects depending on the phantom size, with an intensity decrease of up to 8,25 %. In addition, it was found that the previous setup showed a systematic underestimation of the applied dose by 8,53 %. The comparability of the materials water and RW3 was confirmed regarding their dosimetric properties.
Conclusion and discussion
The results demonstrate the relevance of a standardized quality assurance process for preclinical dose measurements in radiobiology. The 3D-printed phantoms developed make a significant contribution to increasing accuracy and reproducibility and enable a reduction in systematic uncertainties. They thus make a significant contribution to the standardization of radiobiological experiments in heavy ion therapy and improve the comparability of future research results.

Date of Award	2025
Original language	German (Austria)
Awarding Institution	FH Gesundheitsberufe OÖ GmbH
Supervisor	Hermann Fuchs (Supervisor) & Mario Scheweder (Supervisor)