When clicking "Annotations" a menu is displayed, allowing to perform the following measurements:
The line between two points.
When drawing a line that is near horizontal, it will be adjusted automatically to a line that is perfectly horizontal with respect to the image.
The same applies for a vertical line.
You can recognize it by the following symbol:
If this behavior is undesired, press the SHIFT key while drawing the line.
- Measure the difference in length between 2 lines.
- Measure the length ratio of 2 lines.
- Select if your personal annotations, marked in green, are displayed or not.
For ease of use, you can use the following short cuts:
|Length measurement||R + left mouse button down|
|Circle||C + left mouse button down|
|Line||L + left mouse button down|
|Angle measurement||G + left mouse button down|
|Cobb angle measurement||A + left mouse button down|
|Length Loss||D + left mouse button down|
|Length Ratio||H + left mouse button down|
|Show all annotations||CTRL + A (keyboard)|
|Hide all annotations||CTRL + A (keyboard)|
|Delete Annotation||Select annotation + 'Delete' button|
Administrators of a radiology service can delete annotations, by selecting the annotation and hitting the 'Delete' button.
Touch events on mobile devices
Independent of the selected image control or image editing tool, it is possible to drag or zoom in or out on the image:
- Zoom: pinch in or out on an image to zoom in or zoom out
- Pan: Hold two fingers on the image and move them simultaneously to drag the image
All image control and image editing tools can be used when set active by touching the screen with one finger.
E.g.: Use the scroll tool by sliding one finger up and down the image
Be aware: the following features cannot be used when your device is on IOS12:
- Region Zoom
- Stepless Zoom
- Zoom out
→ You can use pinching in/out instead, as described above.
- Density measurement
- Spatial locator
- Window level
→ You can use presets.
- Adding and modifying annotations
The PACSonWEB measuring functions contain length measurements, angle measurements and density measurements based on the information that is provided by the original modality.
Length measurements are expressed in millimeters (mm).
Angle measurements are expressed in degrees (°).
Density measurements are expressed in the unit, as provided by the modality : Hounsfield Unit (HU), Optical Density (OD) or UnSpecified (US).
For measurement precision within the PACSonWEB environment, PACSonWEB relies on the precision of the information that is provided by this modality.
In case a measurements displays "N/A" as the resulting value, it implies that the original DICOM images do not contain the required information to perform a quantitative measurement.
The accuracy of the modality is defined by the PixelSpacing that can be verified by performing a right click on the related image and selecting the option “Show DICOM tags”.
The resolution (x,y) is available in the Dicom Tag “PixelSpacing” (0028,0030) and is expressed in mm.
The resulting value for a measurement within PACSonWEB, will always be displayed with two decimals as a result of the calculations, performed on the data provided by the modality.
A maximal deviance on a performed measurement of √(x²+y²) must however be taken into account.
The accuracy of the different measurements have been validated for length measurements up to 0,01 mm and up to 1° for angle measurements.
In case a measurement is made in another CE class IIa approved DICOM viewer for comparison, it must be taken into account that the measurement accuracy is affected by the coordinates of the start and end point of the line. PACSonWEB only allows measurement points to be set on pixel
crossings. In case the DICOM viewer, used for comparison, allows any point to be selected to perform a measurement, again, a maximal deviance of √(x²+y²) can occur.
Besides the measurement accuracy, we take a rounding factor into account of maximum 0,05 mm for comparison of both resulting values since it cannot be guaranteed that the user who performs the measurement selects exactly the same pixels on the image in both viewers.
In case a measurement is performed in an external PACS system and imported in PACSonWEB, the imported measurements can differ slightly when displayed in PACSonWEB. As the coordinates of the measurement points can deviate from the points, used in PACSonWEB, the resulting value will also deviate. In order to indicate that the value in PACSonWEB is not exactly the same as the one from the original measurement, the value will be preceded by a '~'.