Serial Section SEM Alignment for nm-Resolution 3D Imaging
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Solution Overview
Problem
Scanning electron microscopes struggle to efficiently navigate and align serial sections of tissue samples, leading to lengthy identification times and inefficient data acquisition due to the destruction of samples during imaging and the inability to reimagine sections.
Innovation Solution
A method involving coarse and fine alignment procedures using optical and electron beam imaging to precisely locate and align specimen sections, allowing for high-resolution imaging of selected portions with minimal variability, using feature-based image registration and correlation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual navigation and alignment of serial sections is performed by an SEM technician, then alignment precision can be achieved, but imaging time increases from many hours to days
Solution Approach 1:
The patent applies preliminary action by capturing overview images of all serial sections before high-resolution imaging. These overview images are processed in advance to automatically identify and align section locations, so that when high-resolution imaging begins, the system already knows where to position the beam for each section. This pre-processing step eliminates the need for manual navigation during the time-consuming high-resolution imaging phase.
Solution Approach 2:
The patent uses overview images as simplified copies or representations of the actual serial sections. Instead of manually navigating to locate features in each high-resolution section, the system creates a lower-resolution map (overview image) that captures the spatial arrangement of all sections. This copy is then used to guide the alignment process, replacing manual visual inspection and navigation.
2Loss of information
If high resolution image data is obtained from entire tissue blocks, then complete ultrastructural information is achieved, but data volume reaches 3 petabytes and recording time extends to 10^5 days
Solution Approach 1:
The patent applies segmentation by dividing the tissue block into multiple thin serial sections (100-300 sections at 50 nm thickness each). Instead of attempting to image the entire 1 mm³ block at high resolution simultaneously, the system processes each section separately. This segmentation reduces the data volume and imaging time for each individual section while maintaining complete ultrastructural information across the entire tissue volume through the stack of sections.
Solution Approach 2:
The patent extracts only the essential ultrastructural information needed for analysis by imaging serial sections at high resolution rather than attempting to capture the entire tissue block. The system extracts relevant cellular and subcellular structures from each section at nm-resolution, discarding the unnecessary bulk tissue data. This extraction approach maintains scientific value while dramatically reducing data volume from petabytes to manageable sizes.
3Adaptability or versatility
If serial sections are cut and placed on conductive support for Array Tomography, then sections can be re-imaged as needed, but navigation to the same area in each section becomes the main bottleneck
Solution Approach 1:
The patent implements feedback by capturing overview images of each serial section that provide spatial orientation and location information. These overview images serve as feedback to the alignment system, allowing automatic identification of corresponding features across sections. The system uses this feedback from the overview images to adjust and refine the positioning and alignment of each section, making navigation automatic rather than manually challenging.
Solution Approach 2:
The patent introduces overview images as an intermediary between the physical serial sections and the alignment process. Instead of directly manipulating and navigating to locate features in each high-resolution section (which is operationally difficult), the system uses the intermediary overview images to establish spatial relationships. This intermediary layer simplifies the operation by providing a simplified visual reference for alignment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and precise alignment of specimen sections, reducing imaging time and sample destruction, facilitating high-resolution 3D reconstruction with minimal operator intervention.
Implementation Method 1
An optical imager is situated to obtain an overview image of a substrate that includes a plurality of specimen sections
Implementation Method 2
A charged particle beam (CPB) imaging system is coupled to obtain electron beam based images of the specimen sections and selected portions thereof
Implementation Method 3
The preview images are processed for registration based on at least one feature in one or more of the preview images
Data Source
AI summary
Methods of aligning specimen images of specimen sections situated on a substrate include obtaining an optical or SEM image of the substrate and locating and aligning optical or SEM images of each specimen section. The specimen sections are then imaged with an SEM to obtain preview images, and a region of interest (ROI) in at least one of the preview images is selected. The preview images are processed so that at least portions of the preview images proximate the ROI are aligned. Based on the alignment of the preview images, final SEM image of selected specimen sections are obtained so that a set of images aligned in three dimensions is available. Image alignment can use cross-correlation with a fixed or variable reference that can be updated as specimen section images are processed.