Radonc/BME Medical Image and
Computational Analysis Laboratory
Steven Toffel
BS Biology, pre-Med
2015-16 College of Medicine Junior Honors Program
Graduation: May 2016
Currently: 2nd year medical student, University of Florida

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  1. Resume (pdf)
  2. Research Overview

    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).
  3. National Presentations
    Wilhelm M., Begosh-Mayne D., O'Dell W.
          Pulmonary vascular pruning in response to radiation
          Radiation Research Society 60th Annual Meeting, Las Vegas, NV, Sept. 2014

  4. Related MIACALab projects
    1. Vessel Segmentation
    2. Lung radiation dose response

  5. Close Research Collaborators
    1. W. O'Dell (Radiation Oncology Research)
    2. Dustin Begosh-Mayne
    3. Matt Wilhelm