The current window level and width values are displayed in the top right-hand corner of the window. If the Adjust W/L tool on the toolbar is active, these changes are made holding the button which the tool was activated. To learn more about tool control, see Section 1.14.
In the Volume Reconstruction tab or Multiplanar Reconstruction tab, you can also activate the tool from the right-click menu of the image. In the Flat Image Viewer tab, the tool is available in the Image section of the main menu. In the Multiplanar Reconstruction tab, the tool is available in the MPR section of the main menu. In the Volume Reconstruction tab, the tool is available in the Volume section of the main menu.
To change the parameters, move the mouse in the study window, holding the button which the tool was activated
to increase the window level — up;
to reduce the window level — down;
to reduce the window width — left;
to increase the window width — right.
If you haven’t activated any tools with the right mouse button, you can change the window width and level by moving the mouse while holding the right button. In the Controllers tab of the Image viewer module (see Section 15.5.1), you can choose the mouse button which will be used by default to change the window parameters.
The terms "window width" and "window level" in digital images commonly refer to "contrast" and "brightness" respectively on your computer.
For certain types of tissues, the DICOM Viewer has preset width and level values. To change the width and level settings, click the arrow on the right-hand side of the Custom W/L button . The following preset values are available in the drop-down menu (see Figure 2.16):
Recommended — the settings are considered to be optimal by the DICOM Viewer. They are used by default.
Bones — for viewing bone tissues.
Lung — for viewing lung tissues.
Brain — for viewing brain tissues.
Chest — for viewing chest tissues.
Headneck — for viewing head and neck tissues.
Abdomen — for viewing abdominal tissues.
Full dynamic — the mode where the window width and level depends on the image parameters available. This mode is used when the window width and level is not mentioned in the study.
Custom W/L... — the window width and level parameters are provided by the user in the W/L settings dialog box (see Figure 2.17) and are used for all the images in the series.
To select one of the modes without the preview option, click on the arrow on the right side of the button. You cannot edit the values predefined for specific tissues. To return to the original settings, select the Recommended mode.
To customize the window width and level settings, click the Custom W/L button . In the W/L settings dialog box (Figure 2.17) that pops up, provide the window width and level parameters or choose the preset values you need.
You cannot edit the values predefined for specific tissues.
Click OK to apply the settings or Cancel to cancel.
To enable additional image viewer settings, proceed as follows:
Choose Settings... in the Options menu.
Choose Image viewer in the Modules list and click the Settings button.
From the Image viewer settings window, go to the W/L settings dialog box (Figure 2.18).
For the Flat Image Viewer mode, select the following options:
To calculate the Recommended and Full dynamic values and apply them to all the slices in the study, check the box Use the same W/L value for all images in Series. If you do not select this option, the Recommended and Full dynamic values will be calculated for each slice separately.
If there are frames in the study and the box Use the same W/L value for all images in Series has been checked, the maximum and the minimum window width and level for the Full dynamic mode will be chosen from all the frames. If you haven’t checked this box, the values for the Full dynamic mode will be calculated for the current frame.
If the window width and level values provided in the series tags are incorrect, check the box Recalculate recommended W/L. The recommended values are calculated on the basis of the image properties. The values provided in the series tags are ignored.
To set the default window width and level values for the DSA mode, check the Default DSA W/L. Provide the required numerical values in the Width and Center boxes.
Click OK to apply the settings or Cancel to cancel.
The options Use the same W/L value for all images in Series and Recalculate recommended W/L impact the window width and level values in the Recommended and Full dynamic modes.
To restore the default settings, click the Defaults button.
To use the values provided in the W/L settings dialog box (Figure 2.17) when viewing merged series, proceed as follows:
In the list of layers for the merged series, choose any except the first (base) layer. For details on series fusion, see Chapter 4. In the W/L settings dialog box (Figure 2.17), provide the window width and level parameters or choose the preset values you need for this layer.
Open the merged series in the Volume Reconstruction or Multiplanar Reconstruction tab by pressing the respective button on the toolbar.
The width and level parameters for the first (base) layer are taken from the series tags. For the other layers, the width and level parameters are chosen by the user in the tab for merging layers.