EduceLab CT Pixel Calculator

A standalone web tool for estimating Cone Beam CT (CBCT) geometry, voxel size, and sampling strategies. Designed to help researchers optimize scan settings based on object size and specific machine constraints.

Features

1. Geometry Optimization

• System Presets: Pre-configured constraints for EduceLab systems: Waygate V|tome|x M300 and Bruker Skyscan 1273.
• Auto-Optimize Mode: Automatically calculates the optimal Source-Object Distance (SOD) and Source-Detector Distance (SDD) to maximize resolution while keeping the object within the detector's field of view.
• Manual Mode: Allows fine-tuning of distances. When switching from Auto to Manual, the calculator pre-fills the inputs with the optimal values as a starting point.
• Double-Wide (Offset) Support: Calculates geometry for offset scans (virtual detector extension) if the system supports it.

2. Real-Time Visualization

• Interactive 2D canvas visualization showing the X-ray source, object position, detector active area, and safety margins.
• Visual feedback for object collisions or field-of-view violations.

3. Sampling Strategy Assistant

Calculates the required number of projections based on the Crowther Criterion (Nyquist sampling) to prevent aliasing artifacts. It provides four tiers of recommendations:

• Nyquist Limit (1x): The theoretical limit for perfect reconstruction.
• High Quality (2x): Recommended for standard, high-detail scans (undersampled by factor of 2).
• Fast Scan (3x): For high-throughput or quick preview scans.
• Custom Step: Allows users to input a specific rotational step size (e.g., 0.25°) to see the resulting Effective Resolution.

4. Custom Configuration

• Manual Intrinsics: Modify pixel pitch, detector width, and travel limits directly in the UI.
• JSON Import: Load custom machine configurations via a JSON file.

Quick Start

1. Download index.html.
2. Open the file in any modern web browser (Chrome, Firefox, Edge, Safari).
3. Select your CT System from the dropdown.
4. Enter your Object Diameter (mm).
5. View the Projected Pixel Size and Sampling Recommendations immediately.

Custom System Configuration

You can load your own CT system parameters by clicking "Load Config JSON". The file should follow this structure:

{
  "name": "My Custom CT",
  "pixelPitch": 0.2,
  "widthPx": 2048,
  "minSOD": 10,
  "maxSOD": 900,
  "minSDD": 1000,
  "maxSDD": 1000,
  "maxObjectDiameter": 400,
  "allowDoubleWide": true,
  "overlapPx": 150
}

Field	Description
pixelPitch	Detector pixel size in mm.
widthPx	Physical width of the detector in pixels.
minSOD / maxSOD	Mechanical travel limits for the stage.
minSDD / maxSDD	Mechanical travel limits for the detector.
allowDoubleWide	true if the system supports offset scans.
overlapPx	Number of pixels of overlap required for offset scans.

Sampling Logic

The calculator estimates the Effective Resolution based on the rotational step size.

• Formula: Arc Length ≈ Radius × Step(rad).
• If the Arc Length is larger than the projected pixel size, the effective resolution is limited by the sampling rate rather than the magnification.