Small Area Imaging Gamma Camera
A portable, high-resolution nuclear imaging device: conceived, built and taken to the clinic.
Traditional gamma cameras are bulky, expensive and immobile. SAIGC is a handheld small field-of-view camera built on a segmented cadmium zinc telluride detector that operates at room temperature: high enough in resolution for organ-specific diagnostics, small enough to bring to the patient, and roughly a tenth of the cost of comparable instruments on the market.
correlation with gold-standard LFOV cameras
- Central field of view
- 88 × 88 mm
- Detector elements
- 1,936
- Intrinsic spatial resolution
- 2 mm
- Cheaper than market alternatives
- 10×
Summary
What the work set out to do, and the reasoning that shaped it.
The clinical need was specific: handheld small field-of-view gamma cameras that deliver higher spatial resolution than traditional bulky systems, suitable for intraoperative imaging and organ-specific diagnostics. The design objective followed from it: low cost, robust, ergonomic, and capable of real-time diagnostic imaging.
Development began analytically. Monte Carlo simulations on the GEANT4 and GATE platforms were used to optimise detector geometry and material composition before any hardware was committed, comparing lanthanum bromide (LaBr₃) scintillators against cadmium zinc telluride (CZT) semiconductor alloys.
CZT was selected for the final design as a direct conversion element. Because it converts gamma photons to charge without an intermediate light stage, it permits a far more compact form factor: the property that makes a genuinely portable camera possible.
Impact
What changed as a result.
SAIGC demonstrated 100% correlation with gold-standard large field-of-view gamma cameras in clinical trials: the benchmark that determines whether an instrument is a curiosity or a diagnostic tool.
The camera successfully imaged the full range of thyroid presentations: hyperthyroid, hypothyroid, Grave's disease, thyroiditis and thyroid cancer.
The use of CZT to build a room-temperature mobile gamma camera produced diagnostic images five times better in detail and quality, at roughly one-tenth the cost of most devices available on the market.
The design and its intraoperative capabilities led to the filing of product and design patents.
Figures
The work, drawn.
Purpose-built diagrams: each one carries an idea that prose alone would take a page to deliver.
Direct conversion detector architecture
CZT converts gamma photons straight to charge: no scintillator, no photomultiplier, no depth. This is the decision that makes the camera portable.
System form factor
88 × 88 mm central field of view over a 44 × 44 element matrix, with interchangeable LEHR and pinhole collimation.
Fully digital acquisition chain
List-mode capture on a 12-bit ADC preserves spectral information end to end, so energy discrimination becomes a post-processing decision.
Clinical validation range
Thyroid presentations successfully imaged during trials, each correlated against gold-standard large field-of-view systems.
Methods
How it was done.
Monte Carlo simulation before silicon
GEANT4 and GATE were used to model detector geometry and material response, allowing the LaBr₃ versus CZT decision to be settled on simulated evidence rather than trial fabrication.
Direct conversion detection
CZT converts incident gamma photons directly into an electrical charge, eliminating the scintillator-plus-photomultiplier stack. This is what collapses the depth of the detector head and makes the instrument portable.
Segmented detector array
1,936 individual elements in a 44 × 44 matrix, each 2 mm × 2 mm, give an intrinsic spatial resolution of 2 mm across an 88 × 88 mm central field of view.
Custom collimation
Low Energy High Resolution (LEHR) adaptors were designed for the system, with pinhole collimator support for focused high-resolution studies such as parathyroid imaging.
Fully digital, list-mode acquisition
A 12-bit ADC captures events in list mode, preserving spectral information rather than discarding it at acquisition time: so energy windows and corrections can be decided after the scan, not before.
Specifications
The numbers.
Development timeline
From simulation to the clinic.
Analytical modelling
Monte Carlo simulation in GEANT4 and GATE to optimise detector geometry and material composition.
Material selection
LaBr₃ scintillators evaluated against CZT semiconductor alloys. CZT selected as a direct conversion element for compactness.
Detector and collimator design
44 × 44 segmented array at 2 mm pitch; custom LEHR adaptors and pinhole collimator support.
Digital acquisition chain
Fully digital list-mode acquisition on a 12-bit ADC, preserving spectral information for post-hoc analysis.
Computational acceleration
MLEM reconstruction moved to a Xilinx Virtex-7 VC709 FPGA via High-Level Synthesis; ADSP-BF609 with PVP for clinical post-processing.
Productisation and clinical trial
Transition from laboratory assembly to a portable, medical-grade product with a dedicated clinical user interface. 100% correlation with gold-standard LFOV cameras.
Outcomes
- A portable, medical-grade gamma camera with a dedicated clinical user interface
- 100% correlation with gold-standard large field-of-view gamma cameras
- Diagnostic imaging across hyperthyroid, hypothyroid, Grave's disease, thyroiditis and thyroid cancer
- Product and design patents filed
- Doctoral thesis, SSSIHL, 2020
Collaborators & support
- Sri Sathya Sai Institute of Higher Learning
- Department of Science and Technology (DST)
Funded under
DST · INR 96 Lakhs
2016-2021 · Project Associate
DAE-BRNS · INR 70 Lakhs
2012-2015 · Project Associate
Related outputs