NTCP shift in radiotherapy of lung cancer when changing either the radiobiologic models or the photon dose calculation algorithms. (September 2016)

• Record Type: Journal Article
• Authors: Chaikh, Abdulhamid; Balosso, Jacques
• Is Part Of: Physica medica. Volume 32(2016)Supplement 3
• Page Start: 268
• Publication Date: 2016-09
• Subjects: Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2016.07.584
• Languages: English
• ISSNs: 1120-1797

Abstract

Abstract : Introduction and purpose: In radiotherapy the tumor control and the Normal Tissues Complication Probability (NTCP) are directly correlated to the delivered dose. The purpose of this work is to evaluate and quantify the variations of NTCP for lung when changing radiobiological models or dose calculation algorithms. Materials and methods: Twelve radiotherapy treatment plans were generated. The doses were calculated using the former Pencil Beam Modified Batho (PB-MB) with 1D density correction and the Anisotropic Analytical Algorithm (AAA). Data derived from dose volume histograms (DVH) for healthy lung were compared. NTCP for lung pneumonitis was computed using two radiobiological models: Lyman et al. (LKB) and Equivalent Uniform dose (EUD). Seven sets of radiobiological parameters were tested to explore the best correlation predicting the NTCP, based on dosimetric data, using Spearman's rank test. The bootstrap method was used to estimate the 95% confidence intervals, and the Wilcoxon paired test to calculate p -values. Results: The DVHs showed that AAA predicted higher dose for lung than PB-MB. Consistently, AAA predicted significantly higher NTCP values than PB-MB with p < 0.01; this difference can reach 20% depending on radiobiological parameters and models. Spearman's test indicated a strong correlation with mean dose, V20 and V30. Conclusion: This study confirms that relevant radiobiological parameters should be re-established for the most recent, and now recommended, algorithms such as AAA or AcurosXB to obtain trustable predictions of pneumonitis toxicity and avoid over/under estimated NTCP. This is critical if medical decisions have to be based on NTCP estimations. Disclosure: None.