ESTRO 2022 - Abstract Book

S904

Abstract book

ESTRO 2022

Conclusion Our data, although based on a small number of patients and limited by the observational nature of the study, showed that the safety profile of the Moderna mRNA-1273 vaccine does not raise any specific concerns in pts with cancer who received RT in the past 6 months. We showed high level of antibodies in the 67.7% of the population evaluated for the humoral response.

PO-1068 Challenges of developing an automatic bone marrow contouring algorithm: the SPORADIC project

J.L. Lopez Guerra 1 , P. Gómez-Millán 2 , M. Perucha 3 , J. Pérez-Carrasco 4 , B. Acha 5 , C. Serrano 4 , B.D. Delgado León 1 , O. Muñoz Muñoz 6 , C. Suárez-Mejías 7 1 Insitituto de Biomedicina de Sevilla, Universidad de Sevilla-CSIC-Hospital Universitario V. del Rocío, Radiation Oncology , Seville, Spain; 2 Virgen del Rocío University Hospital, Radiology, Seville, Spain; 3 Virgen del Rocío University Hospital, Medical Physics , Seville, Spain; 4 University of Seville, Signal and Communications Theory, Seville, Spain; 5 University of Seville, Signal and Communications Theory , Seville, Spain; 6 Virgen del Rocío University Hospital, Radiation Oncology , Seville, Spain; 7 Virgen Macarena University Hospital, Technological Information and Innovation, Seville, Spain Purpose or Objective A major health concern for subjects with lung cancer is the decrease in bone marrow and blood cells during and after thoracic radio(chemo)therapy. Segmentation is an important and challenging task in the automatic image analysis of bone marrow. This project addresses the design and preliminary analysis of an automatic bone marrow contouring algorithm. Materials and Methods For the development of the automated algorithm, a technique of statistical methods and Max-flow has been used. This technique combines gray information and statistical information derived from combined distance histograms to feed a convex relaxation algorithm for fast and accurate segmentation of bone structures. Two different segmentation methods have been carried out that differ in the initial treatment of the image: 1) The first is based on performing thresholding. The objective of thresholding is to separate the set of data available in the image into two levels or main values, so that they are differentiated from the rest of the values present. A value of 60UH has been used for the threshold, so that all values below this are discarded, except those that are within pixels of higher values. In this way, only the bone structures (high UH values) and the bone marrow (pixels included within the bone contours) are highlighted. To differentiate between bone and marrow, a new thresholding is performed with a value of 315 UH that separates the bone marrow and bone pixels below and above said value respectively; 2) The second method works directly with the available values from the image and calculates a mean value for bone marrow and bone. Extreme values below 60UH and above 1500UH are ruled out. Results We first segmented manually 2 cases and were used for training and evaluation purposes. The automated segmentation of the bone marrow with Method 1 conforms more precisely to the contours made manually than automated segmentation with Method 2, where the structures marked as bone marrow exceed the manual contours to a greater extent and are located in areas in which there is no bone marrow such as the mediastinal region and cartilage sacks. This is shown in the Table with significantly higher sensitivity and positive predictive values for Method 1 (0.39 and 0.55 respectively in Case 1; 0.55 and 0.66 for Case 2) compare with Method 2 (0.03 and 0.21 in Case 1; 0.12 and 0.47 in Case 2). The DICE and Jaccard coefficients are also of higher value, indicative of a greater similarity between the segmentations of the two cases performed with Method 1 than those performed with Method 2.

Conclusion The preliminary results of the current work regarding the development of the automated algorithm for bone marrow segmentation, although limited, provide a promising starting point from which to develop a robust segmentation algorithmThe algorithm will help physicians and physicists in the radiation planning and the analysis of potential constraints associated with haematological toxicity.