Standard Tumor is a modal sheet used to create a tumor with an elliptical base. It is accessed by clicking the Std. button in the Retinal Diagram Window. In this sheet you can adjust parameters for tumor size, shape, orientation, dosimetric margin and location on the retina. In the Size group you can set radial and circumferential base dimensions, apex height, tilt (rotation about the tumor axis) and margin size and display properties. In the Location group you can set the longitude (or clock meridian) and lattitude of the tumor center.
The default location for the Standard Tumor sheet is top-center in the Retinal Diagram Window. You can reposition the sheet to the top-left, top-right, bottom-left, bottom center or bottom-right if it is obscuring your view of the tumor.
Use the bumper arrows to adjust the various size and location parameters or type values in the text fields. When you accept changes to the values in the text fields with the return key, or use the bumpers, or click the Show button at the base of the sheet, the proposed new tumor base will appear in the retina window outlined using orange dashed lines (the current tumor base is also displayed in the usual manner). To accept the proposed new tumor, click the OK button to exit the sheet. It is often sufficient to enter the radial and circumferential base dimensions and height and then exit the dialog. You can then simply drag the tumor to the desired location on the retinal diagram.
The buttons in the Shape group select the basic tumor solid geometry and launch the Custom Tumor Shape sheet wherein you can further customize the tumor model. PS defaults to a dome shaped tumor. Other supported solid geometries include a conic peak, a truncated conic, a slab of constant thickness and a pair of mushoom-like shapes.
Graphic display of the chord distances (e.g. macula-to-tumor (MT) and disc-to-tumor (DT)) which were required for the Collaborative Ocular Melanoma Study (COMS) can be enabled when you enter this sheet by clicking the Show COMS checkbox. The COMS distances for the current tumor are displayed in the Tumor Summary table on page 1 of the Summary documents. COMS distances for the proposed standard tumor are displayed in the sheet.
The radial and circumferential fields in the size control group of the standard tumor sheet assume that the base of the tumor is spherical.
The radial and circumferential parameter fields in the size control group of the standard tumor sheet assume that the perimeter of the tumor base is a spherical polygon, ie that the basal surface is a segment of a spherical surface. When the shape of the eye model anterior to the equator is an oblate spheroid, e.g. the ratio of the anterior semiaxes is less than 1.0, the base of an anteriorly located tumor is projected onto the oblate spheroidal surface resulting in a small shrinkage of its final perimeter dimensions. The actual radial and circumferential dimensions of the resulting tumor perimeter are displayed in the oblate column of the size control group.
Anterior to the equator, the shape of most eyes is slightly oblate. In the Eye Size window, E (the ratio of anterior semiaxes) will therefore typically be a bit less than 1.0, so the spherical dimensions of anterior tumors will typically be a bit greater than the oblate dimensions.
If the actual dimensions of the resulting tumor vary by more than 0.1 mm from the requested dimensions, the dimensions displayed in the oblate column of the size control group will change color to red. For anterior tumors in oblate eyes, adjust the radial and circumferential sphere dimensions as necessary to achieve the desired oblate dimensions.