In this article the authors proposes to use the scanning force microscope to aid in volume determination of selected specimens. The scanning force microscope itself is able to yield a three dimensional topographical image of the surface of specimens. The authors chose to use the scanning force microscope over other microscopes such as the transmission electron microscope (TEM) because of their ability to directly determine the volume of specimens. In this particular case the authors were able to use the unique features of the scanning force microscope to aid in the volume determination of human metaphase chromosomes.

To begin with the authors had to prepare specimens to undergo the procedure. They point out that because of the variety of differences and techniques in specimen preparation that there will exist a degree of variability in volume determination for the same specimen. Thus, any data yielded by their experiment should be seen as the apparent volume determination for that particular specimen. In the case of human metaphase chromosomes the author chose to use the air dry technique because of its conventional use in karyotyping.

The algorithm used in calculating volume determination involved a complex series of steps in which the image generated was broken down and analyzed. Images of the specimens in questions were separated from background images sand artifacts so as not to have these influence the true volume determination. The authors explain their difficulty in choosing a critical point for the algorithm (in order to cut off the specimen from the background) and the consequences of choosing a value that was either too high or too low. In the end they chose to use a value one height unit above the highest background feature. After that the volume of the specimen could be determined by integrating the height values of the remaining image (i.e. the true specimen)

The numerical value obtained for the volume determination of human metaphase chromosomes was 25.5 +/- 3.4 mm3 . These results using this method were found to be comparable and in some cases even more accurate that those used by other more conventional methods such as TEM. The authors plan to due further studies with other specimens and compare their data with that obtained by other methods as a further application of this novel method.