Preview SRS Layout

Use this command to preview a fractionator scan before it is implemented to help you determine whether the sampling parameters are adequate. If there is more than one closed contour in the current tracing, displays an aerial view of the data.

Procedure

1. Optional: Define a counting frame.
2. Click Probes>Tools>Preview SRS Layout.
3. Click a contour to select it. displays the Preview SRS Layout window.
   

   To exclude nested contours, go to File>Preferences>Stereology Preferences>SRS and check the Exclude nested contours box.

4. Enter a grid size. If you don't know the exact grid size:
   1.  Enter a value in the Desired sampling sites field.
   2. Click the Estimate Grid Size button.
      • The X and Y values are determined by the size and shape of the selected closed contour.
      • You can change them or round them (e.g., 250 instead of 244.54).
5. The program displays an aerial view of the contour with a grid of counting frames overlaying it.
   • The total number of counting frames depends on the size and shape of the selected closed contour, the size of the counting frames and their distance from each other.
   • The total number of sites is displayed in the status bar on the right.

   Each time the Preview is run, a different layout is presented. This is because a new random starting point for the grid placement is used.
   Do not repeat the Preview until you find a layout that you find satisfactory because it introduces bias. Instead, use the preview to get a general sense of how many counting frames in the XY grid will overlay your region of interest, and to adjust the grid settings accordingly.

6. If the number of sampling sites appears inadequate, modify the parameters.

    Repeat steps 2-4. To decrease the total number of sites, use larger values for X and Y. Conversely, to increase the total number of sites, use smaller values for X and Y.

   If the preview shows that the sites are applied to a location in your tissue that is not representative, do not start another preview to get a better layout. Accepting the random placement of the sampling sites is a key component to systematic random sampling and stereological principles.

7. Click anywhere in the tracing window to turn off the aerial preview display.
8. Select a probe.

 

You can use Preview SRS Layout while a fractionator probe is in progress to see an overview of the status of the probe. If you select Preview SRS Layout while a fractionator probe is running, an aerial display of the current probe is shown with the current counting frame blinking.