Objectives: A comparison of the treatment-plans quality and the radiobiological impact of dynamic field (Sliding Window (SW/IMRT), Volumetric Modulated Arc-Therapy (VMAT) and Helical Tomotherapy (HT) plans for oropharyngeal carcinoma. Methods: Three cohorts of patients were selected, planned and treated with one of three IMRT techniques and the plans compared dosimetricaly and radiobiologically. In-house software computed Equivalent Uniform Dose (EUD); a second piece of software was developed

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... compute NTCP using the Lyman Kutcher Burman models. The risk of cancer induction was estimated from the integral dose (ID). Results: The three types of IMRT plan yielded similar dose distributions. The hot spot in HT yielded Dmax < 105% of Dpres. The EUDs were maximized over the PTVs and reduced for all structures treated by HT compared to SW and VMAT. All NTCPs were less than 5% except for the parotid glands. The second cancer risk varied with the type of IMRT. Conclusion: EUD, NTCP and ID assessment in addition to dosimetric parameters evaluation confirm that the three techniques are equivalent dosimetrically, but HT offers better radiobiologically sparing of structures in case of oropharyngeal cancer. Advances in Knowledge: This paper is a complete study compared to all studies given above in a lot of journals. It concerns three novel IMRT techniques of treatment, where we find the dosimetric evaluation and the biologic impact of each modality of treatment at the first time and we give an estimation of induced second cancer for each one in the second part.