Accuracy of measurementsTopic number: 1425412373663

Various factors affect how accurate Image area measurements area.

WARNING! The accuracy of measurement results is influenced by a number of factors that are beyond the control of the software: The quality of the input data, including the accuracy of the modality The appropriate placement of points on the screen. If measurement points are placed on an image that is zoomed out, several pixels of the image are projected onto a single display pixel, thus lowering the accuracy of placement. Inaccurate measurements can cause wrong treatment. Therefore, do not base treatment or diagnosis solely on measurements made with this application.

For measurements done in axial view, the maximum error margin is = 2 * SQRT (2) * s = 2.8284 * s.

When using coronal or sagittal views, the error margin depends on the slice spacing.

For angle measurements, accuracy depends on the length of the line segments used to compute the angle. Short lines with a length close to the length measurement error will produce inaccurate results. Long lines with measurement error insignificant compared to their total length will produce accurate results.

Accuracy constraints are that:

• The image is not lossy compressed or subject to any other processing that decreases quality
• The image has been properly calibrated to provide valid pixel spacing information
• The monitor has been properly calibrated, if true size measurements are used
• The image is zoomed to at least a 1:1 zoom factor before placing measurement points
• The user is trained and performs the measurement according to best current practice

The accuracy of the display depends on the total magnitude of the value. For example, a value of 1.53255 mm will be displayed as 1.53 mm while a value of 123.55353 mm will be displayed as 123 mm.