ESTRO 38 Abstract book

S386 ESTRO 38

Strasbourg, France ; 7 Tours Regional University Center, Radiation Oncology, Tours, France ; 8 Curie Institue, Radiation Oncology, Paris / Orsay, France ; 9 Jean Bernard Radiation Oncology Center, Radiation Oncology, Le Mans, France ; 10 Centre médico –chirurgical – ELSAN, Radiology, Aurillac, France ; 11 Lorraine Institute of Cancerology - Alexis-Vautrin Comprehensive Cancer Center, Statistic, Vandœuvre-lès-Nancy, France ; 12 University hospital of Amiens, Neurosurgery, Amiens, France ; 13 Pitié-Salpêtrière University Hospital, Neuroradiology, Paris, France ; 14 Besançon Regional University Hospital Center, pathology, Besançon, France Purpose or Objective Intensity-modulated radiation therapy (IMRT) treatment plans for head and neck cancer typically use a high number of radiation fields and may be associated with new beam- path non-target tissue toxicities, particularly nausea and vomiting. The dorsal vagal complex (DVC), including the area postrema, the nucleus of the solitary tract and the dorsal motor nucleus of the vagus, is a little known structure of the brainstem which may be implicated in the radiation-induced nausea and vomiting (RINV).The objective of our project was to define consensus guidelines for delineating the DVC. Material and Methods The DVC was identified on autopsy sections and endoscopic descriptions. Anatomic landmarks and boundaries were used to establish radio-anatomic correlations on CT and Magnetic Resonance Imaging (MRI). The DVC delineation was performed on MRI images and reported on CT scans. Next, guidelines were provided to eight radiation oncologists (the working group, WG) for delineation guidance of this structure on DICOM-RT images of two patients being treated for a nasopharyngeal carcinoma. The evaluation of the variability of contours was benchmarked using a ‘‘experts’ reference contour” (delineated with the help of three experts of the brainstem: HMD, DH, and ML). Firstly, each volume submitted by the eight radiation oncologists was compared with the reference volume. Secondly, different indices reflecting the correlation of the volume with the ‘‘experts’ reference contour” were calculated: the Volume Ratio (VR), the Common Delineated Volume (CDV), and the Additional Delineated Volume (ADV). Then, the kappa index (KI) and the Overlap Volume (OV) were calculated. Results The DVC was defined with a concise description of its main anatomic boundaries. The caudal limit of the DVC is easily determined on a MRI sagittal view of the brainstem and must be delineated in the transversal plane of the obex, which is also in the plane of the central canal aperture (Fig 1). The DVC is located on both sides of the median sulcus of the medulla oblongata. In order to be more reproducible, we proposed delineating a 4-mm diameter circle which included the different parts of the DVC (Fig 2). The craniocaudal length of the DVC is 5 mm. The interobserver analysis showed that the DVC delineation was reproducible. The average volume and height of the DVC delineated by the WG were not significantly different from that of the expert with a result of 0.13 cm 3 (95% CI: 0.12–0.14) ( p = 0.5 ) and 0.5 cm ( p = 1 ), respectively. The different indices obtained by the WG compared to the expert were 0.98 (95% CI: 0.64–1.08) for the VR, 71% (95% CI: 44–87) for CDV, 27% (95% CI: 16–38) for the ADV, 0.58 (95% CI: 0.33–0.84) for the OV and 0.72 (CI 95%: 0.50–0.91) for the KI.

PO-0753 radiotherapy quality assurance-POLCA trial- patients with anaplastic oligodendroglial tumors L. Feuvret 1 , H. Douzane 2 , C. Jenny 1 , A. D'Hombres 3 , L. Padovani 4 , M. Aumont 5 , G. Noel 6 , J. Jacob 1 , F.G. Riet 1 , C.H. Canova 1 , C. Dehais 2 , F. Fauchon 7 , Y. Meng 8 , F. Dhermain 9 1 Hôpital Pitié-Salpétrière, RADIATION THERAPY, Paris, France ; 2 Hôpital Pitié-Salpétrière, Neuro Oncology, Paris, France ; 3 Hôpital Lyon Sud, Radiation Therapy, Lyon, France ; 4 APHM, Radiation therapy, Marseille, France ; 5 René Gauducheau, Radiation Therapy, Saint Herblain, France ; 6 Paul Strauss, Radiation Therapy, Strasbourg, France ; 7 Centre des Hautes Energies, Radiation Therapy, Nice, France ; 8 Hôpital d'Argenteuil, Radiation Therapy, Argenteuil, France ; 9 Gustave Roussy, Radiation Therapy, Viillejuif, France Purpose or Objective The ongoing phase III POLCA trial (NCT02444000) was designed to determine whether treating patients with newly diagnosed 1p/19q-codeleted anaplastic gliomas with PCV alone can increase overall survival without neurocognitive deterioration as primary endpoint. The control group treatment is intensity-modulated radiation therapy (IMRT) followed by 6 cycles of PCV chemotherapy and the experimental group treatment 6 cycles of PCV chemotherapy (radiotherapy being deferred at the time of progression) (October 2018: 60 patients in each arm). We report the results of retrospective individual case reviews (ICRs) for the first patients randomized to assess the study All institutions were required to submit the radiotherapy plan of their first randomized patients. Full digital datasets uploaded to the CD rom were assessed by three independent reviewers through the “POLCA quality assurance” ANOCEF group (GRANOCEF). The software Artiview® (Aquilab SAS, France) package allowed experts to review and assess multimodality imaging and radiotherapy treatments. Results Forty-four ICRs from 14 centers were received and assessable. Twenty-three were evaluated as per protocol (53%), 5 as acceptable variation (11%) and 16 as unacceptable variations (36%). Most common unacceptable variations were related to the target volumes delineation (11 cases; 25%), OARs delineation (5 cases; 11%), dosimetric process (4 cases; 9%), dosimetric MRI (1 case; 2%) and no using IMRT (1 case; 2%). Conclusion The ICR analysis showed a significant number of major deviations with potential impact on toxicity profile and/or tumor control. OARs delineation dummy-run, guide book “list of main deviations”, participation to “POLCA quality assurance” ANOCEF group, customized confidential reports may improve quality of radiotherapy technique. Prospective ICRs could prevent and correct protocol violations before starting treatment for future studies. PO-0754 Radiation-induced nausea and vomiting: how to delineate the Dorsal Vagal Complex ? A. Beddok 1 , J. Faivre 2 , A. Coutte 3 , J. Le Guévelou 4 , J. Welmant 5 , J. Clavier 6 , S. Guihard 6 , G. Janoray 7 , V. Calugaru 8 , Y. Pointreau 9 , A. Lacout 10 , J. Salleron 11 , M. Lefranc 12 , D. Hasboun 13 , H. Duvernoy 14 , J. Thariat 4 1 Curie Insitute, Radiation Oncology, Paris / St Cloud, France ; 2 Lorraine Institute of Cancerology - Alexis- Vautrin Comprehensive Cancer Center, Academic Radiation Oncology & Brachytherapy, Vandœuvre-lès- Nancy, France ; 3 University hospital of Amiens, Radiation Oncology, Amiens, France ; 4 François Baclesse Center, Radiation Oncology, Caen, France ; 5 Montpellier Institute of Cancer, Radiation Oncology, Montpellier, France ; 6 Strasbourg Insitute of Cancerology, Radiation Oncology, protocol compliance. Material and Methods