ESTRO 2022 - Abstract Book

S1671

Abstract book

ESTRO 2022

1 Clínica Universidad de Navarra, Oncología Radioterápica, Madrid, Spain; 2 Universidad de Navarra, Departamento de Matemática y Física Aplicada, Pamplona, Spain; 3 Clínica Universidad de Navarra, Radiofísica Hospitalaria, Madrid, Spain; 4 Siemens Healthcare, MR Clinical Scientist, Madrid, Spain; 5 Universidad Carlos III, Ingeniería Biomédica, Madrid, Spain; 6 Clínica Universidad de Navarra, Radiología, Madrid, Spain

Purpose or Objective

Evaluate the possibility of implementing segmentation the vascular tree in treatment planning of Radiotherapy using new imaging methods such as CT-Body perfusion that allows visualization and segmentation of the arterial vessels or the MRI - 4D Flow sequences that allow the quantification of vascular blood.

Materials and Methods

CT-Body Perfusion Between April 2019 and March 2020, 20 patients treated with a radiotherapy component underwent CT-Body-Perfusion, acquiring multiple series, in order to obtain images of the arterial and venous phases after a 1st bolus of contrast. A second static CT is performed after the administration of a second bolus of slow contrast to visualize the entire vascular tree. MRI-4D flow Between March 2021 and July 2021 in 31 patients treated with a radiotherapy component, series of MRI-4D flow images were performed in the context of treatment planning in order to visualize the entire vascular tree, to avoid artifacts in the images are the product of the patient's breathing, gating techniques have been used in the thoracic and abdominal locations. Processing was performed using the SyngoVia system in the CT body perfusion module or MM-reading. Reconstruction of the sequences were exported to RayStation TPS for vessels automatic segmentation. CT-Body Perfusion Approximately 27 to 40 in total series are made in each study with Image sequences every 1.5 seconds. The proportion of supra-infradiaphragmatic locations was 60/40. The exam requires an approximate time of 20 to 30 minutes. MRI-4D flow As a result of acquiring 4D flow images, 2 different types of images are obtained, an anatomical image and a velocity-coded image. The temporal resolution of 41-54 ms, the spatial resolution of 1-1.7 mm3 and VENC = 20-70 cm/s. Approximately 150 slices are made in each series. The supra-infradiaphragmatic ratio was 62/38. Adding the 4D flow sequence to the clinical protocol increases the scan time by 10-20 minutes. Results

Conclusion

The inclusion of advanced imaging techniques would allow the design of vascular structures such as OAR in Radiotherapy treatments in order to develop strategies to predict and, to a certain extent, prevent RT-induced vascular and blood damage. MRI's intrinsic sensitivity to movement offers the unique ability to acquire blood flow simultaneously with the anatomical data within a single measurement and makes it possible to implement vascular segmentation without subjecting the patient to greater exposure to radiation and in a reasonable time.

PO-1886 Dosimetric verification of treatment plans for TBI/TMI on helical tomotherapy.

S. Dubiel 1

1 The Maria Sklodowska-Curie Greater Poland Cancer Centre, Department of Radiotherapy , Pozna ń , Poland

Purpose or Objective The aim of the study was to perform dosimetric verification with measurement array ArcCHECK® Sun Nuclear of 10 patients underwent the total body irradiation (TBI). Retrospective analysis included 10 plans created at helical Tomotherapy in Tomotherapy Planing System (TTPS), Precison Accuray . Materials and Methods The 10 treatment plans of total body irradiation on helical Tomotherapy were prepared. Main assumption was to create treatment plans using <1000 number of iteration in TTPS. Subgroups stratified based on gender, age and body size were analyzed. For dosimetric purpose 9 independent verification plans for 3 random patients (child, adult women and adult man) were performed. Dosimetric verification plans were created for 3 regions of the body - H&N, thorax and pelvis - for each of 3 representative patients. All dosimetric verification plans were measured using measurement array ArcCHECK® - Sun Nuclear and evaluated with gamma index. In this study was used standard quality assurance criteria for IMRT. DTA