Determining RBE for development of lung fibrosis induced by fractionated irradiation with carbon ions utilizing fibrosis index and high-LET BED model

• Verfasst von: Zhou, Cheng [VerfasserIn]
• Verfasst von: Moustafa, Mahmoud [VerfasserIn]
• Verfasst von: Yang, Bing [VerfasserIn]
• Verfasst von: Brons, Stephan [VerfasserIn]
• Verfasst von: Dai, Ying [VerfasserIn]
• Verfasst von: Schwager, Christian [VerfasserIn]
• Verfasst von: Jäkel, Oliver [VerfasserIn]
• Verfasst von: Debus, Jürgen [VerfasserIn]
• Verfasst von: Abdollahi, Amir [VerfasserIn]
• Titel: Determining RBE for development of lung fibrosis induced by fractionated irradiation with carbon ions utilizing fibrosis index and high-LET BED model
• Verf.angabe: Cheng Zhou, Bleddyn Jones, Mahmoud Moustafa, Bing Yang, Stephan Brons, Liji Cao, Ying Dai, Christian Schwager, Ming Chen, Oliver Jaekel, Longhua Chen, Juergen Debus, Amir Abdollahi
• Jahr: 2019
• Jahr des Originals: 2018
• Umfang: 8 S.
• Fussnoten: Available online 2 November 2018 ; Gesehen am 01.04.2020
• Titel Quelle: Enthalten in: Clinical and translational radiation oncology
• Ort Quelle: Amsterdam : Elsevier, 2016
• Jahr Quelle: 2019
• Band/Heft Quelle: 14(2019), Seite 25-32
• ISSN Quelle: 2405-6308
• DOI: doi:10.1016/j.ctro.2018.10.005
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1693739321

Abstract

Carbon ion radiotherapy (CIRT) with raster scanning technology is a promising treatment for lung cancer and thoracic malignancies. Determining normal tissue tolerance of organs at risk is of utmost importance for the success of CIRT. Here we report the relative biological effectiveness (RBE) of CIRT as a function of dose and fractionation for development of pulmonary fibrosis using well established fibrosis index (FI) model.</p><h3>Materials and Methods</h3><p>Dose series of fractionated clinical quality CIRT versus conventional photon irradiation to the whole thorax were compared in C57BL6 mice. Quantitative assessment of pulmonary fibrosis was performed by applying the FI to computed tomography (CT) data acquired 24-weeks post irradiation. RBE was calculated as the ratio of photon to CIRT dose required for the same level of FI. Further RBE predictions were performed using the derived equation from high-linear energy transfer biologically effective dose (high-LET BED) model.</p><h3>Results</h3><p>The averaged lung fibrosis RBE of 5-fraction CIRT schedule was determined as 2.75 ± 0.55. The RBE estimate at the half maximum effective dose (RBE_ED50) was estimated at 2.82 for clinically relevant fractional sizes of 1-6 Gy. At the same dose range, an RBE value of 2.81 ± 0.40 was predicted by the high-LET BED model. The converted biologically effective dose (BED) of CIRT for induction of half maximum FI (BED_ED50) was identified to be 58.12 Gy_3.95. In accordance, an estimated RBE of 2.88 was obtained at the <i>BED_ED50</i> level. The LQ model radiosensitivity parameters for 5-fraction was obtained as α_H = 0.3030 ± 0.0037 Gy⁻¹ and β_H = 0.0056 ± 0.0007 Gy⁻².</p><h3>Conclusion</h3><p>This is the first report of RBE estimation for CIRT with the endpoint of pulmonary fibrosis <i>in-vivo</i>. We proposed in present study a novel way to mathematically modeling RBE by integrating RBE_max and α/β_L based on conventional high-LET BED conception. This model well predicted RBE in the clinically relevant dose range but is sensitive to the uncertainties of α/β estimates from the reference photon irradiation (α/β_L). These findings will assist to eliminate current uncertainties in prediction of CIRT induced normal tissue complications and builds a solid foundation for development of more accurate <i>in-vivo</i> data driven RBE estimates.</p>