Camera-based ionizing radiation analysis
Cover your camera lens completely with any opaque material — black electrical tape, multiple layers of thick cloth, or black foam — to block all visible light. Ionizing radiation (gamma, X-ray, beta) then strikes the CMOS sensor directly, creating bright pixel clusters in an otherwise dark image.
The app captures a continuous stream of video frames, sums them into a single composite image, then subtracts a pre-captured background composite and counts surviving bright pixels as radiation events. This approach has near-zero dead time — the sensor is live for the entire exposure window.
Real-time: Start camera → Capture background → Set exposure time → Start detection
Static: Upload background image → Upload detection image → Adjust threshold → Results auto-update
Calibrate: Use survey meter reading or known source → Get dose rate conversion factor
Video frame stacking: Each video frame has a short shutter (~1–33ms). Instead of one long exposure, the app collects all frames during your chosen exposure time and sums pixel values. A radiation hit — which appears as a spike in a single frame — accumulates in the composite. Background noise appears in every frame and is removed by subtraction.
Why this works: Summing N frames ≈ one N-frame-long exposure with near-zero dead time between samples. Compare: taking one still photo per second leaves the sensor idle between shots.
Pixel-wise: Subtracts each pixel individually — best for sensors with fixed hot pixels or spatial noise patterns.
Mean: Subtracts the global mean brightness — best for uniform sensors.
Hybrid: Uses the larger of pixel-wise and mean — balanced, recommended for most cases.
This tool is significantly less sensitive than dedicated radiation monitoring equipment. CMOS sensors have thin silicon layers and respond only to moderate-to-high radiation fields. Use for educational demonstrations and qualitative checks only — not as a substitute for certified dosimetry instruments.
Follow ALARA principles. Never handle radioactive sources without proper training and authorisation.
Method A — Survey Meter (recommended): Place a source near the covered camera, measure dose rate with a calibrated survey meter at the same point, run a detection to get Net Pixels, then enter both values below.
Method B — Known Source: If you know the isotope and activity, the theoretical dose rate is calculated from the inverse-square law. Useful when no survey meter is available.
After calibration, verify with a fresh measurement — expect ±20–50% uncertainty due to sensor geometry and energy dependence.
Method A: k = Ḣ_meter (in µSv/hr) ÷ (Net Pixels ÷ Exposure Time)
Method B: Ḣ = (Γ × A) / r² → k = Ḣ ÷ (Net Pixels ÷ Exposure Time)
k units: µSv/hr per px/s | Live dose rate = k × net px/s