ESTRO 2024 - Abstract Book

S5258

Radiobiology - Normal tissue radiobiology

ESTRO 2024

6. Monje, M. and J. Dietrich, Cognitive side effects of cancer therapy demonstrate a functional role for adult neurogenesis. Behav Brain Res, 2012. 227(2): p. 376-9.

7. Boutin, H., et al., [18F]DPA-714: direct comparison with [11C]PK11195 in a model of cerebral ischemia in rats. PLoS One, 2013. 8(2): p. e56441.

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Digital Poster

Impact of kV-Cone Beam Computed Tomography Dose on DNA Repair Mechanisms: A pilot study

Christian Popotte 1 , Elise Berthel 2 , Romain Letellier 3 , Mirlande Duclos 2 , Antoine Jehl 2 , Matthieu Stoll 2 , Alessandro Iacovelli 4 , Tiziana Rancati 5 , Melodie Munier 1 , Ester Orlandi 6 , Paul Retif 3 , Sandrine Pereira 2 1 Fibermetrix, R&D, Entzheim, France. 2 Neolys Diagnostics, R&D, Entzheim, France. 3 CHR Metz Thionville, Medical Physics Unit, Metz, France. 4 IRCCS Foundation National Cancer Institute, Radiation Oncology Clinical Department, Milan, Italy. 5 IRCCS Foundation National Cancer Institute, Data Science Unit, Milan, Italy. 6 National Center for Oncological Hadrontherapy (CNAO), Radiation Oncology Clinical Department, Pavia, Italy

Purpose/Objective:

During external radiotherapy treatment, several patient-dependent parameters can cause a modification of the dose distribution compared to the planned distribution. One of the most commonly used solutions to verify these parameters is cone-beam computed tomography (CBCT). However, the CBCT composite dose is rarely reported and/or optimized, even though the repeated CBCT cumulative dose can be up to 3% of the prescription dose. Its potential impact on the patient is still a debate. The adaptive response occurs when cells are exposed to a dose low level of irradiation that does not induce any detectable damage (of the order of cGy or less) then a few hours later treated with a strong dose (several Gy); the cells have a reduced sensitivity to the effects of genotoxic at high doses (Olivieri et al,1984). In this context, this work aimed to determine whether the imaging (priming) dose may impact the final response (Double strand breaks (DSB) repair mechanisms) of tissues to a challenging dose of 2 Gy in healthy tissue cells of Head and Neck cancer patients treated by radiotherapy. We performed the DNA repair analyses on nine primary fibroblast cells of 6 Head and Neck cancer (HNC) patients (pts), two Primary Dermal Normal Human Adult (controls) and one radiosensitive characterized cell line (AG11415, Berthel et al., 2023). HNC patients were treated using IMRT techniques with/without chemotherapy (CHT). Radiosensitive status of HNC patients was previously determined (Pereira et al., submitted). For each cell line, we carry out in blind the RIANS assay (Granzotto et al., 2016). Different endpoints were measured at 0, 10 min, and 24 h post-irradiation for the biomarkers H2AX and pATM. The irradiations were delivered using a Varian TrueBeamTM STX (Palo-Alto, USA) delivering a 6MV delivering a 6MV treatment beam and equipped with a kV-CBCT imaging system, The dose delivered by the kV-CBCT imaging system was measured on the first irradiation with an IVInomad dosimeter and scintillating fiber probes specially designed for the study. The irradiation condition mimics a standard ENT treatment fraction with one CBCT acquisition followed 3 minutes later by a 2 Gy irradiation. To separate the influence of each dose (imaging dose and 2 Gy) in the irradiation sets, the irradiations were repeated for imaging dose only, 2 Gy only, and imaging dose combined with 2 Gy. Analysis of each irradiation condition's impact on DNA repair biomarkers was performed using a Wilcoxon test. Material/Methods: