Photodynamic therapy (PDT) is becoming a treatment of choice for cancer because of
its low cost, high effectiveness and low damage to healthy tissue. Successful PDT outcome
depends on accurate dosimetry, which is currently lacking, leading to variable and/or
ineffective treatment outcome. We report on our research and developmental efforts
towards an implicit dosimetric method for PDT that will provide an accurate assessment of
treatment effectiveness by continuous monitoring of the in vivo drug concentration and the
oxygen concentration in tissue. This approach uses the same tools presently available for
PDT, making it attractive to the health professionals without increasing treatment cost.
Accident victims and victims of explosive devices often suffer from complex maxillofacial
injuries. The lips are one of the most difficult areas of the face to reconstruct after an avulsion.
Lip avulsion results in compromised facial esthetics and functions of speech and mastication.
The process of reconstruction requires assessment of the vascularization of grafted ex vivo
engineered tissue while it is buried underneath the skin. We describe the design and animal
testing of a hand-held surgical probe based upon diffuse correlation spectroscopy to assess
We have developed the necessary theoretical
framework and the basic instrumental design parameters to
enable mapping of subsurface blood dynamics and tissue
oxygenation for patients undergoing skin graft procedures.
This analysis forms the basis for developing a simple patch
geometry, which can be used to map by diffuse optical
techniques blood flow velocity and tissue oxygenation as a
function of depth in subsurface tissue.skin graft, diffuse
correlation analysis, oxygen saturation.
In this paper we present the details of a Diffuse Optical Tomographic (DOT) prototype instrument developed and
characterized at RMD for concurrent operation with Magnetic Resonance Imaging (MRI) to obtain high resolution
spatial and functional images of hypoxic tumor tissue. We have developed a new system designed for in-vivo imaging
of luminescent agents that respond to tissue oxygenation to improve the contrast and spatial resolution of functional
optical images in deep tissue. High-resolution spatial and anatomical information obtained from MRI images is used to
improve the accuracy of the reconstructed optical images. The time domain lifetime imaging module has parallel
acquisition across a cooled 16-element avalanche photodiode (APD) array for high resolution and high throughput
imaging. The low-cost, compact lifetime imager is compatible with high magnetic and RF fields associated with MR
units in hybrid imaging systems. Using this APD module in a dual-modality imaging setup, phantom imaging was
performed to obtain oxygenation images with high resolution and contrast. Optical image reconstruction is aided by
spatial guidance obtained from the actual phantom dimensions to improve the accuracy of these images.
In this work, we present research performed towards the realization of a hypoxia monitor that can detect the onset of
hypoxia within a minute with very low false positive and false negative rates. We report the development of the next-generation
hypoxia monitor with the capability to simultaneously detect various physiological parameters that change in
response to reduced oxygen availability and identify the onset of hypoxia based on the changes in their cross-correlation
signals. Significant improvements are obtained over the conventional techniques that are used currently to measure
some of the physiological parameters including blood oxygen saturation and blood flow velocity. We demonstrate that a
simple patch geometry holding three LEDs and two single photon sensitive detectors can be used to simultaneously
obtain the heart rate, respiratory rate, blood flow velocity and blood oxygen saturation levels and in less than one minute
analyze their cross-correlation signals to identify the onset of hypoxia from the more benign auto-regulatory response to
We provide a detailed signal-to-noise analysis for 3D imaging of luminescence from a biomarker to detect hypoxic
tumors in deep tissue. Preliminary studies on phantom tissues with inclusions and having homogeneous scattering and
absorption coefficient of μs' ~ 15-20 cm-1 and μa ~ 2 cm-1 respectively, are reported as a function of oxygen tension,
luminophore concentration, and tissue depth. The technique's sensitivity in terms of determination of spatial resolution is
In this work, we present research performed to improve the receiver characteristics for underwater imaging applications
using the hybrid lidar-radar detection technique. We report the development of the next-generation coherent heterodyne
receiver using modulation of the optical receiver's amplifier gain. Significant advantages in the receiver specifications
are achieved using a large-area, high gain, low-noise silicon avalanche photodiode (APD) as the photodetector cum
frequency mixer-demodulator. We demonstrate that heterodyne detection by gain modulation of APD can be used to
increase the signal-to-noise ratio, detection sensitivity and bandwidth for the hybrid receiver system.
In this work, we present research in using confocal optical techniques with femtolitre focal volumes and obtain very high
signal-to-noise and signal-to-background ratios for single molecule detection (SMD). We were able to achieve
improved signal strength by using highly fluorescent quantum dots and nanopatterned substrates to obtain plasmon
induced resonant fluorescence enhancement. A method to simultaneously using multiple excitation spots without the
use of confocal apertures and an array of single photon sensitive Geiger mode avalanche photodiodes was used to
increase the throughput of the detection system. Using this highly sensitive SMD system, we detect small quantities of
synthetic DNA through hybridization eliminating the need of polymerase chain reaction.