Sunday, January 11, 2009

Geek of the Week

I received a dubious distinction at work a few days ago: the Geek of the Week certificate. It is an occasional award for the "unquestionable Devotion to Technology and its avoidable Excess." As we would say: every geek has their week, but not every week has a geek.

The award (citation?) arose from this quotation: "Everything was just fine until it sucked the linoleum off the floor." This obviously deserves some explanation.

The place I work does some cutting edge medical research, to say the least. One area we do that in is neurosurgery. To that end, we have a rather specialized neurosurgical suite that has next to it an MRI scanner. In this suite it is possible to perform an MRI scan on someone's head in the middle of a surgery. The skull can even be open during this. This is accomplished by having the surgical table aligned axially with the bore of the MRI magnet. The patient gets moved off the surgical table to a sort of gurney that docks to the MRI scanner. The patient is transferred using a specialized tray of sorts that can be shifted easily from surgical table to gurney to inside the magnet. The transfer from surgical room to MRI scanner is a short roll of about 12 feet. I mean "roll" quite literally, because the gurney moves between the two locations, docking rigidly at either end.

My role in all of this came with the docking of the gurney to the MRI scanner. It was difficult for the person at the foot of the gurney to guide the table (covered in drapes and anesthesia equipement, along with the patient) and line things up right properly, or to know when to decelerate to avoid crashing into the MRI scanner. The concern wasn't necessarily that something would get broken, it's just that a patient in the midst of brain surgery, whose head is clamped to a table and cut open, should be spared any possible jolt. So, the solution I eventually came up with is this:

The Y-shaped track is laid on the floor in front of the MRI scanner. The thing with the white rollers is bolted to the underside of the gurney. As the table to brought close to the scanner, the track and rollers make sure that the gurney is aligned properly with the MRI scanner.

Meanwhile there were also stripes painted to the floor: green, yellow, and red. The flags at green indicated that the front roller was about to engage the track; the yellow flags indicated when the rear roller engaged the track; red indicated that the front of the gurney was touching the dock of the scanner. By watching these flags and the wheels at the foot of the gurney, the driver would better be able to know where he was and how best to control things.

What does this have to do with linoleum? The Y-shaped track that guides the gurney isn't there all the time. It is only needed when the MRI scanner is used in conjunction with an operation next door. Most of the time the scanner is just a scanner, and the red track would just be a trip hazard (that's why it's red, so that you're more likely to see it). So, we needed a way to temporarily anchor the track to the floor. We first considered various anchors (like threaded holes) potted into the concrete subfloor, but opted not to for this reason: in order to function, and MRI scanner must be isolated from any possible radio frequency interference. The way that this is accomplished is to sheath the room in copper - a room-sized Faraday cage.

The people that install, maintain, and baby-sit these very expensive scanners were necessarily wary about us punching holes in the floor, so we gave that up. Instead, we opted for some custom-made suction cups. The suction cups are similar to the ones that a mechanic would use to lift a windshield into place. The suction is applied by flipping a cam lever, similar to how a quick-release works on a bicycle wheel. They work really well, are easy to engage and disengage, and hold better than a molded cup that you squeeze against a surface.

The only problem was that they worked too well. Instead of drawing the track onto the floor, they sucked the floor up - separated it from the concrete beneath. When you took the track away, there would be these two small bulges in the sheet linoleum of the floor. Hence, "Everything was just fine until it sucked the linoleum off the floor." The solution was to cut out that section of linoleum and replace it with a stainless steel plate. This had the added benefit of being a smoother surface to stick to, rather than the textured linoleum, and resulted in a better grip.

So that's my Geek of the Week story.

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