The axial eye modeling tool
  • In the Image window, assure that the Axial image is being displayed and calibrate the image using the Ruler and Calibrate tools.
    CTGroup
  • After calibrating the axial image, turn off the Ruler tool. If you leave the ruler enabled it might overlap the eye in the image and could interfere with your ability to interactively drag the eye sizing tool control points.
  • Click the Eye button in the tools group to display the eye sizing tool.
    ToolsGroup
  • Select left or right eye from the toolbar Eye group. The eye sizing tool orientation will adjust to the selected eye.
    LeftEye
  • Click in the middle of the eye sizing tool and drag the tool over the appropriate eye.
  • Adjust the eye size to match the image by dragging the control markers. You can enlarge the image in the vicinity of the eye using the "magnifier" buttons at the lower left of the window.
  • The red marker rotates the tool. The white markers control the lens size and position. The white and green equatorial markers control the diameter of the eye model. The blue markers adjust the cornea & limbus. The magenta marker adjusts the ellipsoidal appearance of the anterior hemisphere of the model.
  • The yellow lines of the tool represent the angle at the center of the PS model between the posterior pole of the eye and the center of the optic disk. This angle is used to calculate the distance between the posterior pole and the center of the optic disc at the retina which is used to calibrate the fundus collage. Hence, calibrating the axial image and fitting the eye model to the axial image should be your first priority when doing image based planning.
CalibrateCTEyeTool

The 3D model in the setup window will change immediately in response to changes in the eye sizing tool so experiment with the tool's control handles to learn their properties. Place the Setup and Image windows side-by-side as you drag the eye sizing tool control handles to observe the behavior of the model.


All of the eye modeling tools

Open and load other CT or MR image planes in the same way as the axial image. The primary difference between image buffers in PS is that the eye modeling tools differ in appearance. Properly positioning and orienting the eye modeling tools on each image is the ONLY way PS can know how to display the image in 3D space and in 2D planar dosimetry space.

The image that you load into each of Plaque Simulator's five MPR image buffers should follow the file naming conventions for the button associated with that buffer (e.g. the buffer labeled Axial is where you should load the axial MPR that you created using Osirix, in the Equator buffer load the equator MPR and so on). You can, in fact, load almost any kind of image file into these buffers. However, if you load an image different from the button names, PS will not be able to properly calibrate, interpret or display that image, and will not be able to properly overlay isodose lines on the image.

EyeToolAxial

Axial

EyeToolEquatorial

Equatorial

Drag the circular equatorial eye tool to center it over the eye. Using the red control handle, rotate the tool around the ant-post axis (ie center of the tool) to align the 6 and 12 o'clock markers with the true inf-sup axis of the eye. In this example the yellow line in the OsiriX reconstruction indicates the true inf-sup axis of the eye which accounts for 3° of Y-axis head tilt in the CT scanner. This 3° rotation will be propagated to the tumor-coronal image tool. The white and green markers control the diameter of the eye model as in the axial tool.

EyeToolTCor

Tumor-Coronal

Drag the t-coronal eye tool to center it over the eye. The alignment of the eye model to the t-coronal image is critical in order for isodose lines to be properly superimposed on this image. In this example the yellow line in the OsiriX tumor-coronal reconstruction indicates the tumor-meridian plane rather than the inf-sup axis of the eye. In general, use the equator image and tool to acount for Y-axis head rotation in the scanner. The purple markers control the diameter of the external sclera on this image but do not affect the diameter of the eye model. This tool does not know if the t-coronal plane is anterior or posterior to the equator. Therefore, the red circle delimiting the inner sclera (approximating the retina) always adjusts to indicate the location of the posterior inner sclera according to the external diameter on this image and the equatorial diameter of the eye as set in one of the other images.

EyeToolTMer

Tumor-Meridian

Drag the t-merdian eye tool to center it over the eye. The alignment of the eye model to the t-meridian image is critical in order for isodose lines to be properly superimposed on this image. Use the red control handle to rotate the tool around the X (med-lat) axis of the eye (ie center of the tool) to align the ant-post axis with the true ant-post axis of the eye. The white and green markers control the diameter of the eye model as in the axial tool. Use the t-merdian tumor tool to mark the approximate location of the tumor in this plane (not illustrated here).