-<input type="radio" name="IR_Backproj" value="diff2">Difference Optimized<br>
-<input type="radio" name="IR_Backproj" value="idiff2">Difference Optimized (integer math)<br>
-<input type="radio" name="IR_Backproj" value="idiff3" checked>Difference Highly-optimized (integer math)<br>