The accuracy of dynamic predictive autofocusing for whole slide imaging

Area of Science:

• Digital pathology
• Biomedical imaging
• Microscopy automation

Background:

• Whole slide imaging (WSI) automates microscope slide scanning for digital pathology.
• Accurate focusing is crucial for high-quality WSI, but dynamic focusing in continuous motion has been a challenge.
• Previous methods reduced focal planes but weren't applied dynamically during automated scanning.

Purpose of the Study:

• To evaluate a novel autofocusing method in a rapid, continuous scan mode for WSI.
• To measure the accuracy of a dynamic 3-point focus algorithm in a dual-sensor WSI system.
• To assess the efficiency gains of continuous scanning autofocus compared to stop-and-go methods.

Main Methods:

• A rapid 3-point focus algorithm was applied dynamically during continuous scanning.
• Ground truth focal height was established using a "stop and go" scan mode with full z-depth acquisition for over 400 tiles.
• The dynamic algorithm's focal height was compared against the ground truth.

Main Results:

• The average focal height error was 0.30 (±0.27) μm, well within the system's depth of field.
• Approximately 95% of tiles achieved focus within the system's depth of field.
• The continuous scan autofocus method was six times faster than non-continuous scanning.

Conclusions:

• The dynamic 3-point focus algorithm provides highly accurate autofocusing in continuous WSI scanning.
• This method significantly improves scan speed without compromising image quality.
• The findings support the adoption of dynamic, continuous scanning for efficient digital pathology workflows.