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"Fluorescence Imaging Guidance: Toward standardization and smartphone-based devices"

Abstract

Fluorescence imaging for surgical and treatment guidance visualizes clinically relevant biomarkers and has been successfully translated for numerous applications, including tumor margin detection and perfusion visualization. Over the past decade, as imaging technologies have matured to enable seamless integration with clinical workflow, fluorescence-guided surgery (FGS) has become the fastest-growing medical imaging modality. Additionally, the field of treatment guidance using quantitative fluorescence imaging is also rapidly developing. Notably, it has the potential to personalize treatment for a variety of existing standard-of-care medical procedures, including photodynamic therapy (PDT). The use of smartphone-based devices within biomedical imaging has also seen rapid development, promising to provide cost-effective imaging at the point of care.

Here, we present:

1. the development of imaging targets for fluorescence-guided surgical systems;
2. the development of a smartphone-based fluorescence imager for point-of-care treatment guidance of skin photodynamic therapy; and
3. the advancement of treatment guidance for photodynamic therapy dose standardization and of new sunlight-based regimens.

The FGS imaging targets mimic the spectra of indocyanine green (ICG), the most widely used fluorescent agent. These targets were designed to address the unmet need for FGS system characterization, performance monitoring, and inter-system comparisons to ensure patient outcomes across commercially available systems. Methods for 3D printing fluorescent material with tunable optical properties were developed to achieve scalable manufacturing of fluorescent imaging targets with applications beyond ICG-specific imaging.

The smartphone-based fluorescence imager was developed to monitor the accumulation and photobleaching of protoporphyrin IX within clinical photodynamic therapy (PDT). The system design achieved quantitative fluorescence imaging with integrated image processing in a hand-held device. This imager is being used in clinical trials to study personalized PDT treatment and advance sunlight-based regimens.

Optical radiometry techniques of PDT light sources were advanced to guide the delivered effective dose for FDA-approved lamp sources and sunlight-based treatments. A prospective clinical trial was conducted to study the differences in the lesion clearance and treatment mechanisms between lamp-based and indoor-daylight based PDT. The results from the developed methodologies, clinical study, and smartphone imaging aim to guide the advancement of sunlight-based PDT treatments.

Thesis Committee

• Kimberley S. Samkoe, PhD (Advisor and Chair)
• Scott C. Davis, PhD
• Geoffrey P. Luke, PhD
• Jonathan Sorger, PhD (External, Intuitive Surgical)

Contact

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