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PhD Thesis Defense: Daniel Alexander



3:00pm - 4:00pm ET


For Info on how to attend this video conference, please email daniel.a.alexander.TH@dartmouth.edu

"Expanding Cherenkov Imaging Applications in Radiotherapy: Clinic-Wide In Vivo Treatment Monitoring and MR-Linac Quality Assurance"


Radiation therapy treatments have become increasingly complex, striving to improve patient outcomes by delivering sufficient dose for tumor control while sparing more normal tissue. This trend has necessitated the development of additional workflows, such as multilayered incident mitigation strategies and advanced techniques for adapting treatments to account for time-sensitive patient factors. Novel technologies such as optical 3D surface monitoring and magnetic resonance-guided linear accelerators have been developed to assist clinicians in implementing these workflows.

We hypothesize that optical imaging methods developed for radiotherapy dose monitoring and measurement can be used to positively impact modern radiation therapy challenges. Cherenkov imaging allows for visualization of the treatment field in in real-time during treatment and is the first such technology of its kind. The first aim of this thesis work focuses on advancements in the applications of Cherenkov imaging in the radiotherapy clinic, specifically through the detailed quantitative characterization of Cherenkov imaging systems, the capabilities of this technique in the context of complex treatment modalities such as volumetric modulated arc therapy (VMAT), and the quality improvement opportunities afforded by the adoption of continuous, clinic-wide Cherenkov imaging for treatment monitoring.

The second aim of this thesis work focuses on optical imaging-based quality assurance (QA) methods for MR-guided radiotherapy machines. Scintillation and Cherenkov imaging systems provide advantages over current MR-linac QA methods due to associated 2D or 3D detection capabilities and real-time, efficient output. First, a method for daily output and radiation-imaging isocenter coincidence verification was developed using a custom light-emitting, MR-visible phantom. Second, a 2D planar scintillation imaging technique for performing many routine QA tasks was benchmarked for relative accuracy and compared to existing methodologies. Third, a rapid and simple method for acquiring MR-linac beam characterization data using Cherenkov projection imaging is shown as an alternative to traditional time-intensive techniques.

Thesis Committee

  • David Gladstone, ScD (Chair)
  • Brian Pogue, PhD
  • Lesley Jarvis, MD, PhD
  • Petr Bruza, PhD
  • Rongxiao Zhang, PhD
  • Lei Dong, PhD (external)


For more information, contact Theresa Fuller at theresa.d.fuller@dartmouth.edu.