Please cite this article in press as: Di Carlo C, et al. Hippocampal sparing in stereotactic radiotherapy for brain metastases: To contour or not contour the hippocampus? Cancer Radiother (2017), https://doi.org/10.1016/j.canrad.2017.08.113 ARTICLE IN PRESS G Model CANRAD-3699; No. of Pages 6 Cancer/Radiothérapie xxx (2017) xxx–xxx Disponible en ligne sur ScienceDirect www.sciencedirect.com Original article Hippocampal sparing in stereotactic radiotherapy for brain metastases: To contour or not contour the hippocampus? Épargne de l’hippocampe lors de la radiothérapie en conditions stéréotaxiques des métastases cérébrales : faut-il délinéer ou non l’hippocampe ? C. Di Carlo , M. Trignani , L. Caravatta , A. Vinciguerra , A. Augurio , F. Perrotti , M. Di Tommaso , M. Nuzzo , S. Giancaterino , M.D. Falco , D. Genovesi * Department of Radiation Oncology, “G. D’Annunzio” University of Chieti, SS. Annunziata Hospital, Via Dei Vestini, 66100 Chieti, Italy a r t i c l e i n f o Article history: Received 25 January 2017 Received in revised form 23 May 2017 Accepted 10 August 2017 Keywords: Brain metastases Hippocampus Neurocognition Fractionated stereotactic radiotherapy VMAT a b s t r a c t Purpose. – The aim of our study was to evaluate hippocampal irradiation in patients treated with frac- tionated stereotactic brain radiotherapy. Patients and methods. – Retrospective hippocampal dosimetric analysis performed on 22 patients with one to four brain metastases treated with fractionated stereotactic radiotherapy using volumetric intensity-modulated arc therapy. Original plans did not include hippocampus as avoidance structure in optimization criteria; hippocampus was retrospectively delineated on magnetic resonance coregis- tered with planning CT and using as reference the RTOG 0933 atlas. Hippocampus was defined both as a single and as pair organ. Constraints analysed were: Dmax < 16 Gy, D40% < 7.3 Gy, D100% = Dmin < 9 Gy. Assuming a / ratio of 2 Gy, biologically equivalent dose in 2 Gy fractions was calculated. Hippocampal- sparing plans were developed in cases where hippocampal constraints were not respected in the original plan. Results. – Among constraints analysed Dmax and D40% have been exceeded in ten out of 22 cases. The constraints were not respected in patients with more than one metastatic lesion and in three patients with only one lesion. Considering all exceeded constraints values in non-hippocampal sparing plans, the 50% of them was respected after replanning. No significant differences were found among conformity and homogeneity index between non-hippocampal sparing and hippocampal sparing plans. Conclusion. – Volumetric intensity-modulated arc therapy hippocampal sparing plans significantly decreases dose to hippocampus assuring an equal target coverage and organs at risk avoiding. © 2018 Soci ´ et ´ e franc ¸ aise de radioth ´ erapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved. Mots clés : Métastases cérébrales Hippocampe Neurocognition Radiothérapie fractionnée en conditions stéréotaxiques VMAT r é s u m é Objectif de l’étude. – Évaluer l’irradiation de l’hippocampe chez les patients traités par irradiation frac- tionnée cérébrale en conditions stéréotaxiques. Patients et méthodes. – Analyse dosimétrique rétrospective de l’hippocampe conduite chez 22 patients atteints d’une à quatre métastases cérébrales traitées par une irradiation fractionnée en conditions stéréotaxiques en utilisant l’arcthérapie volumétrique modulée. Les plans de traitement originaux ne comprenaient pas l’hippocampe dans les critères d’optimisation ; l’hippocampe a été rétrospectivement délinéé sur l’imagerie par résonance magnétique co-enregistrée avec la scanographie de planification, en utilisant comme référence l’atlas du Radiation Therapy Oncology Group (RTOG) 0933. L’hippocampe a été défini à la fois comme un seul et comme un organe pair. * Corresponding author. E-mail address: d.genovesi@unich.it (D. Genovesi). https://doi.org/10.1016/j.canrad.2017.08.113 1278-3218/© 2018 Soci ´ et ´ e franc ¸ aise de radioth ´ erapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.