ESTRO 2024 - Abstract Book

S4999

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2024

Figure 1: (a) shows histograms averaged across a 10 patient cohort, of air volume expansion before an initial course of radiotherapy, and before a second course months to years later. The inset shows an example of the ventilation data used in the histograms; a map of expansion values for each voxel within the lung volumes. (b) shows the mean expansion values from each ventilation map correlated with FEV1 scores taken at the same time. The histograms in Figure 1 show the percentage of voxels with a given respiration value, with 1 representing a 100% increase in air volume. The two distribution correspond to scans before a 1st and 2nd round of radiotherapy treatment, with a median time between scans of 18 months (range 11-52). There is a systematic drop in the highest functioning regions of the lungs when patients return for a second scan (10±2% reduction in the mean expansion on average). Additionally, the scatter plot shows that where FEV1 values were recorded at the time of a patient's visit, they strongly correlated with the mean expansion values of the ventilation maps.

Conclusion:

Our work shows a strong correlation between ventilation maps and the well established FEV1 metric, as well as a clear physiological change in patients following an initial course of radiotherapy. The decrease in lung function might be explained by many contributing factors; due to damage from the first or second cancer, as a side-effect of treatment, or because of other respiratory diseases, such as COPD. Further analysis will aim to isolate the the relationship between delivered doses and lung function, and could support the case for creating planning structures around high functioning regions where dose could be minimised, with the goal of reducing toxic effects.

Keywords: 4DCT, Lung Ventilation

References:

[1] Brett A Simon, "Non-invasive imaging of regional lung function using x-ray computed tomography," 2000.

[2] Thomas Guerrero, et al. "Dynamic ventilation imaging from four-dimensional computed tomography," in Physics in Medicine and Biology, vol. 51, pp. 777-791, 2006.

[3] Ryan Miller, et al. "Characterizing Pulmonary Function Test Changes for Patients With Lung Cancer Treated on a 2-