While your scanners are fast, they just are not fast enough. Especially if you want to be reasonably sure you did no major reading errors.
What you can do however, is to flash-freeze the brain and instead of recording the electrical patterns scan the frozen-in-place neuro-chemical state. Since the signals travel as a ion concentration shift, interrupted by transmitters and inhibitors, reading them provides the information necessary to recreate the exact thought-pattern at the time of flash-freeze.
The biological substrate can not be unfrozen fast enough to survive the procedure, thus the person being scanned dies. On the plus side, the frozen mind image can be duplicated since you can take your time before starting the digital substrate.
Live backups of a digitized mind may be difficult to achieve, since synchronization strikes again: Your band-with is just too low. To do a copy you have to slow down the digital substrate, but this has a chance of introducing sensory corruption, as the real world still runs normal speed and thus there's too much information for the slowed mind to work on.
Again there might be a way of "flash-freezing" the digitized mind as well, but it is a rather violent procedure, which literally fries the active pattern into the substrate. The chips and boards become trash, as the burned in patterns break them, but hey, you can use them as a kind of snapshot if you need to revive a mind. If you read them like a modern flash-drive recovery though (which is destructive), you may read them only once, so make a proper copy.
Radiation based: the return of synchronization issues
Your Hyper-CT scan literally fries their brain.
A simple CT / MRI is no problem for the brain to handle. But you need to be FAST. To prevent ripping the mind apart by desyncronization of sections of the brain, you have to scan each and every nerve, each electrical and chemical potential within that corresponds to neural information just about instantly.
In fact the maximum time you have is about a quarter of the time it needs for a single neuron activation to take place. As human neurons can fire at a rate of 200 Hz or slightly more that leaves us with (1/800 s =) 1.25 ms or slightly less. Lets assume 1ms and take the rest for safety margins. You want to be reasonably sure to get all relevant info, so you need MANY pictures and they must be taken all at once.
There are about 86 * 10^9 neurons in a typical human brain. We simplify the brain to a sphere. This means a diameter (in neurons) of about 1.24 (the volume-equivalent sphere diameter compared to a cube) times 4'414 (the cubic root of the total neuron-count), which is roughly 5'480. This is the absolute minimum number of scans you need to do, even if all where perfectly spread. To prevent overlap in your scans you could do spherical swipes, which leaves you at least at pi**2 times the scans. This gives us 54'085 scans, which is about 18.5% of the simple assumption (square-root of neurons count (about 293'258)).
54 thousand scans within 1 ms for a single full scan. (Of course you might want to do two scans to reduce read-issues...)
The aproximate dosage of a CT of the head is between 1.6 and 3.2 milli-Sivert (mSv) depending on exact procedure and if there was a contrast substance involved. That leaves us with about 2.4 mSv * 54k scans for a total of 130 Sv. This irradiation is applied just about instantly.
Here's something about acute dosage:
- The LD50[@30days] is at 4-5 Sv
- The first guy to die from the demon core got 5.1 Sv and 25 days
- The second guy got 21 Sv and died after 9 days.
- Boris Korchilov worked in an unshielded live nuclear submarine reaktor. He had 54 Sv and died after 6 days. Your scan is running 2.5 times that!
Finally, since your scan is VERY LIKELY (read certain) to kill said person, you might want to do twice or more times as many scans to ensure data integrity. You don't have a second chance so you might throw any scans you can do and just average your results.