Difference between revisions of "Calculating statistics on VOI groups"
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− | + | The Statistics Generator command on the VOI menu in the MIPAV window opens the Calculate Statistics on VOI Groups window, which allows you to obtain statistics on one VOI or on multiple grouped VOIs. You can save the statistics to a tab-delimited file, which can then be incorporated into a database. <br /> | |
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The Calculate Statistics on VOI Groups dialog box includes three tabs: | The Calculate Statistics on VOI Groups dialog box includes three tabs: | ||
− | + | # ''VOI Selection page'' -On this page you can select the VOIs on which to calculate the statistics. It also allows you to name and save the logging file at the path you choose.<br /> | |
+ | # ''Statistics Options page'' -This page provides a choice of the types of statistics that may be calculated as well as the conditions under which they may be run. <br /> | ||
+ | # ''Logging page'' -This page provides the results of the statistics in a tabular form. Depending on the number of VOIs included in the calculation, the results may include one or more lines of text.<br /> | ||
==VOI Selection page in Calculate Statistics on VOI groups window== | ==VOI Selection page in Calculate Statistics on VOI groups window== |
Revision as of 19:26, 21 February 2012
The Statistics Generator command on the VOI menu in the MIPAV window opens the Calculate Statistics on VOI Groups window, which allows you to obtain statistics on one VOI or on multiple grouped VOIs. You can save the statistics to a tab-delimited file, which can then be incorporated into a database.
The Calculate Statistics on VOI Groups dialog box includes three tabs:
- VOI Selection page -On this page you can select the VOIs on which to calculate the statistics. It also allows you to name and save the logging file at the path you choose.
- Statistics Options page -This page provides a choice of the types of statistics that may be calculated as well as the conditions under which they may be run.
- Logging page -This page provides the results of the statistics in a tabular form. Depending on the number of VOIs included in the calculation, the results may include one or more lines of text.
Contents
VOI Selection page in Calculate Statistics on VOI groups window
VOI groups list-left
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Lists all of the VOIs found on the image.
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VOI groups list-right
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Lists the VOIs on which you plan to calculate statistics.
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Moves all of the VOIs that appear in the VOI groups list on the right to the VOI groups list on the left.
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Moves the selected VOI that appears in the VOI groups list on the right to the VOI groups list on the left.
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Deletes the selected VOI in either the VOI groups list on the left or the VOI groups list on the right.
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Moves the selected VOI in the VOI groups list on the left to the VOI groups list on the right on which you plan to calculate statistics.
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Moves all of the VOIs, whether they are selected or not, in the VOI groups list on the left to the VOI groups list on the right on which you plan to calculate statistics.
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VOI statistics file destination
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Specifies the file path, file name, and file extension to which you want to save the file.
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Browse
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Allows you to navigate to the directory on your workstation or attached disks where you want to store the file.
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Tab-delimited
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Saves the statistics in a comma-separated tab-delimited file. The extension for this file is.TABLE.
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XML
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In development.
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Calculate
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Runs all statistics that are selected on the Statistics Options page according to the options specified.
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Close
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Closes this window.
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Help
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Displays online help for this window.
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Statistics Option page in Calculate Statistics on VOI Groups
Statistics to calculate
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No. of voxels-Indicates the number of voxels-including voxels that span frames in an image stack-enclosed in the VOI.
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Volume-Measures the amount of space occupied by a 3D VOI. To calculate the volume, the software multiplies the number of pixels by the resolution of each dimension.
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Area-Measures the surface of the VOI. To calculate the area, the software multiples the number of pixels by the resolutions of the x and y dimensions.
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Average voxel intensity-Calculates the average intensity of the voxels in the VOI by adding the intensity of all voxels in the VOI and dividing the result by the sum of the voxels.
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Std. dev. of voxel intensity-Calculates the standard deviation of the intensity of the voxels in the VOI.
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Center of mass-Indicates the point at which the whole mass of the VOI is concentrated. It is calculated as the sum of all x coordinates divided by the number of points and the sum of all y coordinates divided by the number of points.
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Principal axis (only 2D)-Calculates the principal axis for 2D images only.
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Eccentricity (only 2D)-Describes the geometric shape of the VOI as an ellipse, with 0 indicating a circle and 1 indicating a straight line.
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Statistics options
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By contour & slice-Runs the selected statistics on both the contour and slice.
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By slice only-Runs the selected statistics on only the slice.
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By total VOI-Runs the selected statistics on the entire VOI.
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Show all totals-Specifies to display all of the totals for __________.
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Pixel exclusion
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Exclude pixels from calculation-Indicates to exclude the pixels in the Pixel range boxes from the calculation. When you select this check box, the Exclude pixels button and the Pixel range boxes become available.
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Exclude pixels-Indicates to exclude the pixels between, above, below, or outside the range shown in the Pixel range boxes.
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Pixel range-Lists a specific range of pixels between, above, below, or outside that should be excluded in the calculations.
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Select all
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Selects all of the statistics listed in the Statistics to calculate group.
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Clear
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Clears all of the statistics listed in the Statistics to calculate group.
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Calculate
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Runs all statistics that are selected on the Statistics Options page according to the options specified.
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Close
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Closes this window.
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Help
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Displays online help for this window.
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When you run statistics on VOIs in an image but want to exclude a specific range of pixels from the calculations, make sure that you do the following:
4 Continue to select statistics and other options for the calculation.
Logging page in the Calculate Statistics on VOI Groups Window
Statistics table
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Lists all of the statistics that were calculated according to the selected statistics and the options specified on the Statistics Options page.
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Calculate
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Runs all statistics that are selected according to the options specified on the Statistics Options page.
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Close
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Closes the window.
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Help
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Displays online help for this window.
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However, you can easily change the file name by typing over the default file name in the VOI statistic file destination box on the VOI Selection page in the Calculate Statistics on VOI Groups window. To change the path, type over the current path, or click Browse to select another path.
When you perform additional calculations on the same or new VOIs on that image or on VOIs in another image, the results of those calculations appear below the earlier run statistics. This allows you to compare the results of both.
When you no longer need the statistics on the Logging page or after you saved them to a file, you can clear, or delete, all of the statistics on the Logging page. To do so, do one of the following:
The software deletes all of the statistics on the Logging page.
Recommendation: It is recommended that you decide in advance on a standard procedure for handling statistics files. That is, do you need to keep them for historical purposes? Do you need to keep statistics on individual images in separate files? If so, you may want to assign unique names to the statistics file for each image. If not, you may want to simply overwrite the statistics file each time you calculate statistics of VOI groups.
If you do not want to keep the statistics in separate files, it may become tiresome to always receive and need to respond to the File Exists message. To this end, the software offers an option for always overwriting the logging files. To use this option, simply select Options > Overwrite File Automatically in the Calculate Statistics on VOI Groups window.