FPGA-Based System for Radiation Energy Histogram Computation using Time-Over-Threshold

Abstract

Personalized dosimetry is essential for optimizing radiopharmaceutical therapy, yet current clinical practice relies on serial hospital imaging that is expensive and limits the number of time-point samples. This thesis presents an FPGA-based system used in the Portable Dosimetry Device (PODD), a compact wireless gamma spectroscopy system for monitoring 177Lu therapy. This thesis focuses on the design and implementation of an FPGA-based real-time energy histogram computation system. The FPGA processes time-over-threshold encoded signals from 16 parallel detector channels, achieving 2.5 ns time binning for pulse width measurement and maintaining 512-bin histograms per channel. The digital processing core integrates with GAGG:Ce/SiPM scintillation detectors and communicates wirelessly via Bluetooth to an Android application. Validation with 177Lu and 22Na radioactive sources demonstrated clearly resolved photopeaks at 113 keV, 208 keV, and 511 keV. The PODD’s compact form factor and wireless operation enable accessible point-of-care dosimetry for personalized radiopharmaceutical therapy.