Hadamard Transform Imaging Paul Holcomb Tasha Nalywajko Melissa Walden

Problem Definition Current 3D imaging systems for brain surgery are too slow and possess too low of a resolution to be effective in an operating room setting

Why is this important? 71% mortality rate for diagnosed brain tumors Correlation between complete resectioning of tumors and improved prognosis Complete resectioning requires knowing the location of the tumor, especially tumor margins Imaging in a clinical setting should be fast

Design Criteria Must produce image in less than 20 minutes (current analysis time) Must accurately reproduce area of interest in the brain Must distinguish healthy versus tumor tissue Must be small enough to be usable in an operating room setting Must interface with operating microscope

Cost/Benefit Analysis Decreased Cost Less downtime in OR No analysis fees Less recurrence of tumors  fewer surgeries Increased Benefit Shorter surgeries Tumor removal: ~100% Improved patient prognosis

Design Objective Construct imaging system using digital micro-mirror device and Hadamard transform for use with operating microscope in a clinical setting

System Design Hadamard Transform Decreased imaging time Increased SNR Hadamard Matrix Definition Inverse Hadamard Transform Digital Micro-mirror Device Allows use of Hadamard Transform

Fourier vs. Hadamard Imaging Wuttig and Riesenburg, “Sensitive Hadamard Transform Imaging Spectrometer”

Design Goals Acquire an accurate image (SNR better than current imaging techniques) of the reflectance spectrum of the brain tissue Image area in a short period of time (less than 20 minutes, optimally less than 3 minutes) Distinguish between normal and tumor tissue using gathered image data

System Diagram Illuminate sample with white light Collect and collimate reflected light Decrease image size to 10mm x 10mm square Disperse image spectrally using diffraction grating Compress image vertically to 160um x 10mm Apply Hadamard matrix with DMD Recollimate image and collect with CCD camera Apply inverse Hadamard transform using software Overlay spectral image with imaged area

Lens system for image demagnification (M = 0.4) Stage 1 Lens system for image demagnification (M = 0.4)

Lens and mirror system for vertical image compression Stage 2 Lens and mirror system for vertical image compression

Drawn to scale…

Design Timeline January: Test white light source and camera lens using reflectance standard, align and test Stage 1 February: Align DMD, align and test Stage 2, align Stage 3 March: Continue Stage 3 alignment, test Stage 3, test system using reflectance standard to determine SNR April: Test system using normal and tumor tissue samples, present data at Senior Design Day