Retrospective: radiation damage and its associated "information limitations".

Area of Science:

• Microscopy
• Biophysics
• Materials Science

Background:

• Radiation damage has historically limited electron microscopy (EM) of biological specimens.
• Rose's empirical relationship helps estimate resolution limits based on contrast and exposure.
• High-resolution imaging currently relies on averaging numerous shot-noise-limited images.

Purpose of the Study:

• To investigate the discrepancy between theoretical signal levels and current electron microscopy image quality.
• To explore beam-induced movement as a limiting factor in high-resolution EM.
• To identify potential strategies for overcoming resolution limitations in biological EM.

Main Methods:

• Analysis of Rose's empirical relationship to estimate resolution limits.
• Evaluation of image averaging techniques for shot-noise-limited data.
• Assessment of beam-induced movement effects on image quality and tomographic reconstruction.

Main Results:

• Current EM images have signal levels significantly below theoretical physical limits.
• Beam-induced movement is identified as a potential cause for reduced image quality.
• This movement can severely limit resolution, particularly in cryo-electron tomography.
• Unpredictable high-quality images suggest movement is not an insurmountable barrier.

Conclusions:

• Beam-induced movement is a critical factor limiting high-resolution electron microscopy of biological specimens.
• Developing new specimen preparation and data collection techniques may mitigate beam-induced movement.
• Overcoming this movement could reduce the reliance on extensive image averaging, enhancing efficiency.