ESTRO 36 Abstract Book

S520 ESTRO 36 _______________________________________________________________________________________________

Results

documentation of available volumetric information through MRI at D and at BT. This 3DMD had been developed by the authors to provide precise reproducible topographic and quantitative information in one comprehensive overview (Fig1). Dimensions of GTV D , HR-CTV and IR-CTV for width, thickness and maximum height (GEC-ESTRO Recommendations) as assessed on MRI D/BT (SE T2 weighted sequences) was drawn at all grid levels and in all 3 dimensions as requested in the 3DMD. The cervical canal was taken as the central axis and the external os (surrogate for flange) as reference for the various dimensions. A qualitative observation was done based on the drawings of all 42 cases on individual maps. A quantitative analysis was done with SPSS v20. The dimensions (height, width and thickness) and volumes were compared and correlated (n= 42). Thereafter another quantitative analysis of the widths of GTVD, HRCTV and IRCTV at 0, 1, 2 and 3 cm and at NMD (Near Maximum distance from the central tandem/central canal) was done (n=84).

We may observe a reduction in dose at V35% and V50% in all OAR and also a reduction in D2cm 3 occurs (Table 1). PTV parameters increase in the case of Axxent, as reported previously, but very few cases of vaginal mucositis have been reported in our center as is showed in another clinical abstract. All patients were treated between 2015 and early 2016, enough time to develop early problems. Conclusion Preliminary results are very optimistic about the adequacy of Xoft equipment for treatment of endometrial cancer with a clear reduction of the physical dose in organs at risk and very few development of acute mucositis despite the considerable increase V150 in the treatment volume. Further studies will be necessary to take into account the RBE in treatments with such sources. PO-0940 3D mapping for precise definition of GTV, CTV and their correlation in cervix cancer BT (EMBRACE) S. Banerjee 1 , R. Pötter 2 , C. Kirisits 2 , K. Majercakova 2 , M.P. Schmid 2 , S.K. Shrivastava 3 , U. Mahantshetty 3 1 Medanta The Medicity, Radiation Oncology, Gurgaon, India 2 Vienna General Hospital- Medical University of Vienna, Departmentof Radiation Oncology, Vienna, Austria 3 Tata Memorial Hospital, Department of Radiation Oncology, Mumbai, India Purpose or Objective Image Guided adaptive Brachytherapy (BT) for cervix cancer is based on MRI and gynaecologic examination (GE) at diagnosis (D) and at BT to define the HR CTV. For documentation of disease at D and at BT schematic mapping diagrams (SMD) are used indicating values for maximum dimensions of GTV at D and at BT. For comprehensive assessment of available volumetric information through MRI at D and at BT an advanced schematic 3D mapping diagram (3DMD) was developed to provide precise reproducible topographic and quantitative information (Fig1). This was used to evaluate the topographic and quantitative relation between GTVD, HR CTV and IR CTV. Material and Methods 42 proven cervical cancer FIGO IIB-IIIB patients from Vienna and Mumbai were selected, mean age was 52 years. All were enrolled in the EMBRACE study and completed the planned treatment with MRI at D and at BT. SMDs from GE with individual tumour contours and dimensions as prescribed for EMBRACE were available. A 3DMD in axial, coronal and sagittal orientation was used with a scale (grid with 10 mm distance) for the precise

Results The dimensions of the HRCTV followed closely that of GTVD, with some variations and exceptions. The IRCTV volumes were closely overlapping the HRCTV volumes. In most of the cases the HRCTV and IRCTV were encompassing the GTVD volumes. For the detailed quantitative results see table 1.