Biomedical Engineering Reference
In-Depth Information
so I have to move the slide a little, in one direction. So that I see
all
the
cells and from the beginning to the end, there'll be about thirty-seven,
thirty-six, thirty-eight turns. If you don't overlap then you can miss the
edge there every time.
(Diana, City lab)
Overlapping was a technique used to ensure that the cytodiagnosticians
saw all the cells on the slide during screening. If not properly conducted they
could miss cells in the intermediary zone. This aspect of screening, described
below by Isabel, a cytodiagnostician at Cyto lab, was in fact stressed by all
the cytodiagnosticians:
… it [the overlapping] is very important, there can be one cell on the
whole slide, and it can lie in between too, so it's very important …
Overlapping was said to 'go by itself ' and similarly to adjusting sharpness
its procedure was not consciously considered during screening, as exemplifi ed
by Beatrice at Cyto lab and Sophie at City lab:
… I just go, I have overlapping programmed into my body, in my
fi ngertips.
… I must make the overlap ten, fi fteen per cent (…) When you are so
experienced as we are, then you know exactly how much you are going
to jump. I sort of
feel
it, it's in my fi ngers.
Sophie, the second cytodiagnostician above, explained that overlapping
was defi ned as an exact percentage. However, she did not make a
mathematical calculation every time she did the zig-zag movement with
the steering control. As shown above, by experience overlapping became
understood as felt and situated in the cytodiagnosticians' fi ngers. One of
my informants, Yvonne, who had been a cytodiagnostician for over thirty
years, explained that she had once tried a device (that was put on the
microscope) to mechanically regulate overlapping. She was generally fond
of and welcomed all kinds of new technology in her work. However, this
device was not of any help as it made the microscope stiff. She realised that
she did not need the device:
YVONNE:
… It was so sluggish because then the whole microscope becomes
like a threshing machine (…) and then you notice, you do it anyway,
because you see it when you move. So then you see when the one cell is
at the other end so to speak. So you do it automatically.
ANETTE:
So you don't jump sort of a few centimetres?
YVONNE:
No, no, oh no. You don't do that you see. And then we counted
when we had that machine. Because that did, I think it was thirty-eight
