Date of Graduation


Document Type


Degree Name

Bachelor of Science in Biomedical Engineering

Degree Level



Biomedical Engineering


Muldoon, Timothy


The study of tumor microvasculature is an important area of interest for research and clinical communities; however, there are significant limitations in the clinical characterization of the tumor microenvironment. Optical methods offer quantitative real-time measurement of tissue structure and perfusion and can be miniaturized for deployment endoscopically into previously inaccessible locations. However, conventional optical methods (i.e., optical coherence tomography, white light endoscopy, etc.) gives limited information about tissue perfusion while the diameter of various optical probes along with the complexity of scanning mechanisms make it difficult to access certain areas. In this study, a new technique for characterizing the tumor microenvironment is presented; Utilizing photon depth penetration information calculated via Monte Carlo simulations along with 2D image data from a phantom-based model, an absorber that lies beneath the surface can be approximated by a point cloud. Being able to approximate an absorber beneath the surface is key in locating important tissue components in practice and would be able to give clinicians a better look at what is happening. To accomplish this, Simulations modeled forward photon transport of a beam of light starting from a source fiber going through tissue and then exiting at the image guide at a variety of different exit positions. These simulations were created with predetermined optical properties based on colon epithelium. This data was then used in conjunction with depth approximations and absorber data obtained through a point cloud system to yield an approximation of an absorber below tissue. Point cloud maps of an estimated absorber were able to be created; however, in the future, they can be refined using multiple source fibers situated around the probe to create multiple projections from different sides.


Monte Carlo Simulations, Transport Scattering Regime