Friday, 23 October 2009

Week 3

The third week in, and things are getting tougher. On the plus side, though, certain things are getting more interesting.

For example, we had a lecture explaining how an MRI (magnetic resonance imaging) scanner is able to capture such detailed images of the brain. Would you like to know how it works?

Essentially, an MRI scanner is a tube containing a very strong magnetic field, thousands of times stronger than the Earth’s gravitational pull. This field is kept constant, so is absolutely uniform at every point within the scanner.

The protons inside the head are all busy jiggling around all over the place, randomly veering around at different angles, but once inside the scanner they all begin to align, with every proton facing the exact same direction, due to the power of the huge magnetic force generated by the machine.

The operator can then send a strong sudden magnetic pulse through the scanner, which flips every single proton in the scanner chamber to one side. To help you imagine this, picture all the protons facing north, and then suddenly being knocked to face east (of course this is not how it happens, but it can be easily visualised).

Now, this is the clever bit. The protons will then flip back to align with ‘north’, only in every different type of tissue this process will take slightly different amounts of time. So, bone, grey matter, white matter, even oxygenated and lesser oxygenated blood, each will take a slightly different time for their protons to recover from the knock in order to face ‘north’.

This different timing for each type of tissue is crucial, as the scanner can keep a record of how long each proton took to recover, and this will effect whether a light or dark patch appears on the screen, giving us a perfect image of the skull, brain and surrounding tissue.

Amazingly, the machine can do this in 3d, so you can then work through sections of the brain as if you were travelling through the body.

It is quite an amazing procedure, and if you are interested you can see more here

On an unrelated note, I had my first bit of coursework due in yesterday, a particularly nasty statistics worksheet. The night before it was to be handed in I had got it all finished, printed off, done and dusted. My first early night in ages, I was actually in bed by 11 which is unheard of.

12:30 a.m, I get a phonecall. It is Melissa, a girl on my course, who I collaborated with on the work. She tells me there was an error in our data, meaning all our calculations were wrong. So, at one in the morning I had no choice but to rewrite the bloody thing from scratch, redoing all my calculations, graphs and tables. I got to bed some time after 4 a.m, a bit of sleep, and handed it in an ten the next morning.


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