Monitoring pulmonary vascular response to radiation in cancer patients
Radiation-Induced Lung Injury
Quantification of early and late effects of radiation-induced lung injury using treatment planning CT image data sets, pre-treatment dose distribution calculations, and follow-up CT images at regular intervals as well as the Human Lung Dose Response program.
Pulmonary Vascular Pruning in Response to Radiation
Quantification of lung vessel pruning due to radiation treatment for cancer using CT image date sets, dose distributions and follow-up CT images at regular intervals.
Mechanism of Radiation Induced Lung Injury
Correlating vessel pruning due to radiation treatment with early and late effects of radiation-induced lung injury and proposal of mechanical and biochemical mediated mechanisms for lung injury.
Background and Significance
The lungs are highly sensitive to radiation due to a large density of vessels and high oxygen concentration. Immediately following radiation, acute endothelial cell damage and inflammatory response leads to blockage of the arterial lumen starting with the small arterioles. This subsequent increase in pulmonary arterial pressure further damages vascular endothelium, leading to progressive occlusion of ever larger arterioles creating an unfavorable positive feedback scenario. Radiation late effects in the lung include fibrosis
that many be secondary to the pulmonary vascular response, but this and other hypotheses have not been studied sufficiently due in part to difficulty in quantifying
these effects in vivo in humans. I have been working on methods to extract and quantify pulmonary vascular and tissue changes from 3D CT chest scans of patients, acquired at repeated intervals before and after radiation exposure.
Figure 1. Time course of vascular changes following whole-lung RT. The image on the left is a CT slice through the patient’s chest with the treatment radiation dose overlaid in color, with white representing the highest dose. The plot on the right illustrates the number of branches (on a Log10 scale) for each of 4 branch radius size ranges. Plotted for each range are data from 6 time points, from pre-treatment to 17 months post-RT. An initial decrease in the number of small vessels is apparent at 3 months and progresses through 7 months post-RT. A partial recovery after 10 months is then seen. All CT images were acquired without contrast and with similar imaging parameters (slice thickness; in-plane pixel size).