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PalmOS PDA Applications: Equivalent Field

The equivalent field is defined as the standard (i.e. circular or square) field that has the same central axis depth dose characteristics as the given non-standard field. The equivalent field calculator implements the tables and equations of BJR Supplement 25 (1996), Day MJ and Aird EGA, The equivalent field method for dose determinations in rectangular fields, Appendix A, Central Axis Depth Dose Data for Use in Radiotherapy: 1996, BJR Supplement 25, pp.138-151. The BJR Supplement 25 tables provide data for rectangular fields up to 60 x 60 cm.

Click here to download the self extracting archive: Eq Field 1.0.0, last updated 9/24/03.

Download: EqField.prc.zip (16K)

Below are some screen captures of the calculator running under the PalmOS 5.2.1 simulator:

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To use, simply fill in the rectangular field width and length, or use the bumper buttons to change the values. Choose the equivalent geometry to calculate from the buttons below the width & lengths fields.

The equivalent square or circle diameter is recalculated automatically any time the bumpers or buttons are used to make changes. If you manually enter data in the text fields, make all necessary changes and then click the "Calculate" button to update the display. The display will also update about 5 seconds after the last change in a text field.

You can experiment with some alternatives to the tables such as the "4 x Area/Perimeter" (4A/P) formula with the buttons in the equivalent field readout bezel (see BJR 25 for details).

Other information about this program is found in the Options menu.

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