Today I get to mess around with our newest cath lab acquisition. Actually I did some initial messing with it doing the acceptance testing earlier this month, but now I get to play and have some geeky medical physicist fun with it.
It's a fairly unique (for the US) system and very cutting edge. As far as I've been told, it's the first system to be installed in the US. A Siemens Axiom Artis with a couple of really large magnets from Stereotaxis used for steering a sepcially designed catheter guide wire through the arteries of the heart.
The x-ray system itself is the first flat panel fluoroscopy unit I've laid my hands on for testing. These things are impressively small and compact. Image quality and performance was ok, but not stunning. Noticed some pixellation getting to the smaller mag modes, but nothing severe.
There are a couple of weeks to go before applications training starts and they put it to clinical use, so this is my last good chance play on it without having to stay after hours. There are a couple of things I plan on checking out.
I'm told the magnets (there are two of them) are 0.7 Tesla permanent magnets, but drop down fairly quickly to about 0.08 Tesla about a meter away. Magnetic fields cause charged particles to move in a circular path, and ion chambers work by measuring ionization in air, so the first thing I was curious about was what kind of an effect the magnets would have on my exposure meters. Further complicating things is that the magnetic field produced by these jammies far from static (which causes much havoc with the angiography unit next door). The magnets articulate and move, which is how the catheter guide is steered. I don't really expect a significant effect, but I don't think it's ever been documented. Maybe I'll even get a short technical note out of it to publish somewhere.
Of course any effect on an ionization chamber while the magnets are articulating is pretty moot, because I don't ever expect to be making exposure measurements while the magnets are being used. But like most physicists, I do things to satisfy my curiosity, and this is definitely one of those things.