Your method on ROI creation seems to work nicely; however, suppose I have two centers that are 10 mm apart. If I make my spheres that have a radius of 8mm then they will overlap. Based on my understanding of your program, the most recent sphere created will be a complete sphere and the previosu one will be a partial sphere. Is there anyway, in 3dcalc or otherwise to make the speheres (assuming we are only dealing with these two) equal volumes -- they will no longer overlap. Half of teh overlap will be attributed to each sphere....
