Protontherapy: state of the art and clinical applications Section: Estado del arte AuthorsIgnacio López Moranchel 1,2,3, Patricia Irene Maurelos Castell 1,4 Position 1) Centro de Formación Profesional San Juan de Dios, (2) GENUD Toledo Research Group. (Universidad de Castilla-La Mancha), (3) Universidad Pontificia Comillas, (4) Hospital Universitario de Fuenlabrada. Contact email: Ignacio.lopez@ciclosformativossjd.es Abstract Proton therapy is the most common form of radiation therapy with heavy particles and in recent years has attracted public attention due to the expectations generated about its effectiveness and the expansion of specialized centers in different countries, including Spain. This qualitative documentary work explores the physical properties of proton therapy, its historical evolution, its advantages and disadvantages, application techniques and evidences of clinical effectiveness compared to photon radiotherapy. The interest in the use of protons is due to its dosimetric behavior that allows a better distribution of the dose in the area to be treated, a lower irradiation of the critical organs of risk and adjoining tissues and, consequently, a lower toxicity. While the main disadvantage is related to the uncertainty that exists in the estimation of the Bragg peak. For the conformation of the proton beam two systems are used, one passive (PSPT), older, and another active in which the protons are magnetically directed on the treatment zone (PBS); it is on this last one that systems are being introduced that improve the precision of the irradiation on the tumor volume (IMRT, SFUD). Currently, proton therapy has not proven to be a more effective and safe treatment than photon therapy for most types of solid tumors studied, although proton therapy has provided better results in certain aspects evaluated for medulloblastoma and some pediatric tumors of the central nervous system, tumors of the base of the skull and uveal melanoma. The general consensus is that there is a need to conduct randomized trials and collect multi-centric outcome data to unequivocally demonstrate the advantage of protons. Keywords: Radiation therapy; Proton therapy; cancer; Particle therapy Versión en Español Título: Protonterapia: estado del arte y aplicaciones clínicas Artículo completo no disponible en este idioma / Full article is not available in this language Bibliography National Cancer Institute [internet]. [citado 20 de abril de 2019]. Disponible en: https://www.cancer.gov/about- cancer/treatment/types/radiation- therapy/external-beamSkowronek J. 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