TY - JOUR
T1 - In vitro measurement of proton RBE
T2 - A multi-centric comparison using a harmonized setup
AU - Sokol, Olga
AU - Frederiksen, Anders Tobias
AU - Sitarz, Mateusz
AU - Sørensen, Brita Singers
AU - Santina, Elham
AU - Smith, Christopher
AU - Warmenhoven, John William
AU - Davídková, Marie
AU - Michaelidesová, Anna Jelínek
AU - Danilová, Irina
AU - Zahradníček, Oldřich
AU - Leite, Amélia Maia
AU - de Marzi, Ludovic
AU - Pouzoulet, Frederic
AU - Olko, Paweł
AU - Miszczyk, Justyna
AU - Orzechowska, Barbara
AU - Papalanis, Eleftherios
AU - Hariri, Mehran
AU - Spiegelberg, Diana
AU - Stenerlöw, Bo
AU - Dasu, Alexandru
AU - Bodenstein, Elisabeth
AU - Beyreuther, Elke
AU - Pawelke, Jörg
AU - Pfitzmann, Dorothee
AU - Kirkby, Karen
AU - Henthorn, Nicholas
AU - Durante, Marco
PY - 2025/7
Y1 - 2025/7
N2 - Background and purpose: This study presents a multi-center comparison of in vitro cell survival measurements and RBE calculations following proton irradiations conducted under harmonized experimental conditions across six European institutions participating in the INSPIRE framework. Materials and methods: V79-4 cells were irradiated using spread-out Bragg peak (SOBP) proton fields of two configurations delivering 6 and 8 Gy with widths of 6 and 4 cm, respectively. Each center adhered to a standardized protocol, utilizing the same phantom design to minimize uncertainties related to sample positioning. X-ray reference irradiations were also performed to assess cell radiosensitivity across the participating centers. Results: Despite the consistent protocol, significant inter-institutional variability was observed in the survival measurements. For both treatment plans, the largest variation was detected in the most distal points of the SOBP (coefficients of variation of 43 % and 60 % for the 6 Gy and 8 Gy plans, respectively). Kruskal-Wallis statistical test confirmed the significant differences between the centers for each of the measured position in the proton field for both SOBP configurations. Discrepancies were observed in calculated RBE data as well, albeit preserving the expected trend for the values to slightly increase towards the distal edge of the SOBP (up to 1.5 and 1.3 for the 6 Gy and 8 Gy plans, respectively). Conclusion: The results of the study highlight the minimal biological variation one could expect performing proton RBE measurements in well-aligned experimental conditions and challenges in conducting large-scale, multi-center radiobiological experiments and inter-comparisons between literature data sets.
AB - Background and purpose: This study presents a multi-center comparison of in vitro cell survival measurements and RBE calculations following proton irradiations conducted under harmonized experimental conditions across six European institutions participating in the INSPIRE framework. Materials and methods: V79-4 cells were irradiated using spread-out Bragg peak (SOBP) proton fields of two configurations delivering 6 and 8 Gy with widths of 6 and 4 cm, respectively. Each center adhered to a standardized protocol, utilizing the same phantom design to minimize uncertainties related to sample positioning. X-ray reference irradiations were also performed to assess cell radiosensitivity across the participating centers. Results: Despite the consistent protocol, significant inter-institutional variability was observed in the survival measurements. For both treatment plans, the largest variation was detected in the most distal points of the SOBP (coefficients of variation of 43 % and 60 % for the 6 Gy and 8 Gy plans, respectively). Kruskal-Wallis statistical test confirmed the significant differences between the centers for each of the measured position in the proton field for both SOBP configurations. Discrepancies were observed in calculated RBE data as well, albeit preserving the expected trend for the values to slightly increase towards the distal edge of the SOBP (up to 1.5 and 1.3 for the 6 Gy and 8 Gy plans, respectively). Conclusion: The results of the study highlight the minimal biological variation one could expect performing proton RBE measurements in well-aligned experimental conditions and challenges in conducting large-scale, multi-center radiobiological experiments and inter-comparisons between literature data sets.
KW - Cell survival
KW - Proton therapy
KW - Relative biological effectiveness
UR - https://www.scopus.com/pages/publications/105004934850
U2 - 10.1016/j.ctro.2025.100978
DO - 10.1016/j.ctro.2025.100978
M3 - Journal article
C2 - 40485910
AN - SCOPUS:105004934850
SN - 2405-6308
VL - 53
JO - Clinical and Translational Radiation Oncology
JF - Clinical and Translational Radiation Oncology
M1 - 100978
ER -