RT Simulator User's Guide
Importing Litebox Images
To import Litebox images into RT Simulator you will need to copy the folder containing the images from the Litebox station (or the tutorial CD) onto your computer. If you moved images over a network, now is a good time to end the network connection so you don't accidentally open the images on the Litebox itself.
When you first launch RT Simulator you will be presented with the startup wizard. Select Import a set of CT images and click the OK button.
The startup wizard will lead you through the process of importing images and preparing them for planning.
If the startup wizard has been disabled you can always select Import from the File menu in RT Simulator and then prepare the images in whatever sequence you prefer.
When the MacOS navigation services dialog appears select Siemens Litebox from the Import type popup menu. The Litebox type does not require batch loading. It is a directory file which in turn contains the names of all the individual image files.
Use the navigation facilities to locate the folder containg your Litebox images. In this example, I know that the images are on the Patients 1 partition of my hard disk.
Find and open the folder containing the Litebox images, select the Litebox directory file (the icon is a stack of CT documents with a band around them), and click the Choose button.
After the images load, RT Simulator will perform a validation check looking for images with duplicate table positions (Z coordinates) and oddball pixel sizes and alert you if problems are found. In this example, RT Simulator found one image whose pixel size differed from the majority of the images. Suspicious images are usually scouts. You should click OK in response to this alert.
If you clicked OK to the alert, you will be taken to the Image Series Validation dialog. RT Simulator will create a list of all images and underline the images it feels are the oddballs. At first, RT Simulator assumes that all images are type transverse. In this case, the suspicious image is indeed a scout. You can tell RT Simulator that this is a scout image by clicking the Change type button.
In the Change image type dialog use the menus to select the target mode and index for this image and click the OK button. In this example we are changing Transverse image #0 into type Scout image #0.
After changing the type you will be returned to the series validation dialog. Image #0 will have been reassigned as type scout. Click the OK button to exit this dialog.
You can preview any image in the series by clicking on it. A thumbnail of the 1st highlighted selection in the list is displayed. In some cases you may need to actually delete images. Some examples of images which should be deleted are duplicate table coordinates and oddball table elevations. To delete an image, highlight it in the list and click the Delete highlighted button. You can return to this dialog at any time by selecting the Series validation... item under RT Simulator's Images menu. Click the OK button to exit this dialog.
RT Simulator will now ask you to confirm that the imaging and treatment orientations match. If you are planning to treat your patient Head 1st supine you had better have imaged them the same way. RT Simulator has several mechanisms to compensate for incorrect imaging such as the ability invert the z coordinates, mirror left-to-right, and rotate images about the Z axis. The use of these tools is beyond the scope of this introduction and is covered elsewhere in the users guide. Click the OK button to exit this dialog.
RT Simulator will now alert you to set window and level for the images. You should click the Yes button .
The Window & Level dialog creates a histogram of image pixel values. The default is to plot the contents of only the image currently displayed in the Images window. Click the Pixels from all transverse images button, wait for the progress indicator to finish, and then click the Find range button. Once you know the settings for your CT scanner you can preset these values in RT Simulator's Preferences. The Zoom slider on the right provides more (or less) detail near the bottom of the histogram.
Drag the red boundry lines on the histogram to optimize the 256 gray level display to the soft tissue region of the image. This will also remove unwanted low density objects such as the couch and positioning devices from the image. The objective here is to be able to see the target and prepare the images so that the autocontouring algorithms can find a clean external contour for each slice. You may also need to drag the blue line to mark water calibration for CT images.
Pixels with values greater than the upper (right) red boundry will be remapped to bone density and pixels with values less than the lower red boundry will be remapped to air density. Pixels with values outside the min-max range (0..4000 in this example) will be ignored and are mapped to air density. The numbers displayed above the boundry lines are the number of pixels in that bin of the histogram.
Click the OK button to exit this dialog.
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