Doctoral thesis · 2020
A doctorate in Medical Instrumentation from Sri Sathya Sai Institute of Higher Learning, documenting the full arc of an instrument: from Monte Carlo simulation to a device used on patients.
Structure
The thesis follows the instrument: why it was needed, what it should be made of, how it was built, how it was made fast enough, and whether it worked.
The clinical need for handheld Small Field of View gamma cameras that provide higher spatial resolution than traditional bulky systems, suitable for intraoperative imaging and organ-specific diagnostics. The goal: a low-cost, robust, ergonomically designed system capable of real-time diagnostic imaging.
Analytical modelling using Monte Carlo simulations on the GEANT4 and GATE platforms to optimise detector geometry and material composition. Lanthanum bromide (LaBr₃) scintillators compared against cadmium zinc telluride (CZT) semiconductor alloys. CZT selected as a direct conversion element, permitting a more compact form factor.
An 88 × 88 mm central field of view over a segmented detector of 1,936 elements in a 44 × 44 matrix, each 2 mm × 2 mm, giving 2 mm intrinsic spatial resolution. Custom Low Energy High Resolution adaptors with pinhole collimator support. Fully digital list-mode acquisition on a 12-bit ADC.
Overcoming the computational bottleneck of iterative reconstruction. A parallel MLEM architecture on a Xilinx Virtex-7 VC709 FPGA via High-Level Synthesis achieved 288× speed-up over optimised Intel Xeon software. An Analog Devices ADSP-BF609 with Pipelined Vision Processor accelerated diagnostic calculations by 250%.
Transition from laboratory assembly to a portable, medical-grade product with a dedicated clinical user interface. 100% correlation with gold-standard large field-of-view gamma cameras. Successful imaging across hyperthyroid, hypothyroid, Grave's disease, thyroiditis and thyroid cancer. Product and design patents filed.
Thesis figures
CZT converts gamma photons straight to charge: no scintillator, no photomultiplier, no depth. This is the decision that makes the camera portable.
88 × 88 mm central field of view over a 44 × 44 element matrix, with interchangeable LEHR and pinhole collimation.
List-mode capture on a 12-bit ADC preserves spectral information end to end, so energy discrimination becomes a post-processing decision.
Thyroid presentations successfully imaged during trials, each correlated against gold-standard large field-of-view systems.
Research journey
2012-2015
Rebuilding and upgrading a planar gamma camera as project associate. Detector knowledge acquired by hand.
2016-2021
SAIGC conceived, simulated, designed, accelerated and clinically validated. Doctorate conferred 2020.
2017-2023
SAIGC-Torch: dual-modality intraoperative navigation as Principal Investigator.
2025-2027
Edge AI with Analog Devices; AI/ML for optical networks with NOKIA.