ESTRO 2020 Abstract Book

S996 ESTRO 2020

Table. 1 Calculated group mean, systematic and random registration errors in LR and SI direction. Conclusion Rigid image registration of online MONACO was quantitatively assessed through a phantom study. Image registration deviation from the ground truth physical shift was within sub-millimeter, indicating the good registration performance of online Monaco on Unity MR-Linac for clinical applications. PO-1786 Online IGRT-Halcyon specific guidance parameters in automatic matching for prostate cancer patients M. Altabas Gonzalez 1 , X. Maldonado Pijoan 1 , L.J. Fernández Rodriguez 2 , E. Castillo Elias 1 , B. Pérez Esteve 1 , M. Comino Muriano 1 , Y. Carrera García 1 , J. Matheos Pérez 1 , A. Jurado Martínez 1 , M.D.M. Ramírez Cruz 1 , A. Palma Evans 1 , D. Garcia Relancio 1 , J. Giralt Lopez de Sagredo 1 1 Hospital Universitario Vall d'Hebron, Radiation Oncology, Barcelona, Spain ; 2 Hospital de Alta Complejidad Virgen de la Puerta - EsSalud - Universidad Privada Antenor Orrego, Departamento de Ayuda al Diagnóstico y Tratamiento, Trujillo, Peru Purpose or Objective The Halcyon™ system has been engineered with treatment planning algorithms to simplify and streamline clinical workflow for online image-guided intensity-modulated radiotherapy. The purpose of this work was to assess if there is any improvement in the target matching values between pretreatment KvCBCT and planning CT when online specific guidance parameters in the automatic matching are added to the predefined IGRT-Halcyon 2.0 algorithm in the localized prostate cancer treatments. Material and Methods Between June and August 2019, 46 patients with localized prostate cancer were treated in the Halcyon 2.0 linear accelerator with Volumetric Modulated Arc Therapy to a dose between 72-77 Gy (2.4-2.2 Gy/d in 30 or 35 fractions) with daily correction of the target position based on kvCBCT imaging. The workflow in all patients were an online automatic matching, followed by a visual verification and manual adjustment when required, mainly focused in the proper location of the CTV, surrounded by the anterior wall of the rectum, the base of the bladder, the bulb of the penis and the lateral borders of the prostate. Two automatic matching protocols were used. In the first 23 patients (group 1), the parameters predefined in the Halcyon™ system were apply for an automatic matching of the images. In the remaining patients (group 2), these parameters were modified, limiting the volume of interest to PTV + 1cm and prioritizing the soft tissue. Independent t-test and Mann-Whitney U test were used for comparing groups. The association between automatic and manual adjustment matching was determined using linear regression. Results A total of 1442 CBCT were analyzed, 715 in the group 1 and 727 in the group 2. In both groups, the mean difference in the vertical (VRT) setup correction between automatic and manual adjustment was < 1mm, that was statistically significant (Group 1: -0.74mm 95%CI -0.89; -0.59; and Group 2: - 0.87mm 95%CI -1.04; -0.71;p<0.001) (Table 1), being their linear correlation in this same axis strong (R 2 >0.7), higher in group 1 (Group 1 R 2 =0.840 and Group 2 R 2 =0.737) (Fig. 1a-b). There were no differences in other axis. The values of the corrections required between the automatic comparison and the manual adjustment are not different between the two groups (p=0.65) (Table 1 Fig. 1c).

We have observed that the 17 patients who had a mean difference of more than 2mm between automatic and manual matching (8 in group 1; 9 in group 2) had not undergone good rectal preparation during treatment. In the other 29 patients, random differences greater than 3mm were consistent with a poor rectal conditioning as well.

Conclusion Due to the differences observed between automatic matching and manual adjustment on the VRT axis, the visual verification of the automatic matching should always be performed pretreatment. Optimization of the automatic matching with specific guidance parameters doesn't provide any improvement in the Halcyon system. Poor rectal preparation of the patient leads to worse automatic matching. PO-1787 Radiotherapy process management using InSightive: optimization, evaluation and verification M. Raczkowski 1 , M. Janiszewska 1 , T. Siudziński 1 , A. Maciejczyk 2 1 Lower Silesian Oncology Center, Medical Physics Departmen, Wroclaw, Poland ; 2 Lower Silesian Oncology Center, Department of Radiotherapy, Wroclaw, Poland Purpose or Objective The aim of the work is to present the results of the mechanism of optimization of the radiotherapy process using the InSightive analytical tool. The starting point for the optimization of the radiotherapy process was to create well-defined paths in the Aria system (Care Path) for specific locations, techniques and radiotherapeutic procedures. Optimization of the necessary resources and time needed to complete individual tasks has become the starting point for optimization of the entire process. Material and Methods The InSightive system is based on an intuitive analytical solution allowing easy adaptation to the specifics of the work of a given oncology department. Simple, interactive dashboards allow you to explore data stored in the Aria system. Analysis of the data generated at each stage of the preparation and implementation of radiation therapy allows the detection of certain behavioral patterns and trends that can potentially lead to improved operational efficiency and optimization of the entire process. Results The first stage of the optimization process was the construction of management schemes for defined groups of clinical cases. In the second stage, the time needed to implement individual tasks for the given scheme and the time between them was analyzed. The average duration of defined tasks was determined and individual cases not meeting the assumed criteria were analyzed. The analysis of data for 2019 (picture 1) indicates a downward trend in