X-Ray Consent

DaveS2 said:
Not only standard X-Ray machines, but the CT scanner works the in the same way. MRI is very different, in that it uses high intensity magnetic pulses.

Dave
Click to expand...


MRI's don't use magnetic pulses.
 
POAH said:
they need to know how much you get as over time the more you are exposed to the higher the risk of DNA damage (thymidine dimers in case you are interested). anything that has the potential to damage you have to be asked for consent. You don't have to have an x-ray.
Click to expand...

What they keep check of how many X-Rays you have? Initially my Doctor said she would like me to have four X-Rays, both hands and both knees. She looked at my records and then said, I will only ask them to do both hands and one knee. hmm
 
POAH said:
MRI's don't use magnetic pulses.
Click to expand...

I'm always willing to listen to those better informed than myself, but as I understand it, MRI stands for Magnetic Resonance Imaging.

It use both a high intensity Magnetic field, and Radio Waves to produce an image of the body.

The tapping and knocking you hear during an MRI scan is caused by magnetic coils that switch on and off during the scan. Therefore, by definition, if the magnetic field is switched on and off, then it is pulsed.

Dave
 
DaveS2 said:
I'm always willing to listen to those better informed than myself, but as I understand it, MRI stands for Magnetic Resonance Imaging.

It use both a high intensity Magnetic field, and Radio Waves to produce an image of the body.

The tapping and knocking you hear during an MRI scan is caused by magnetic coils that switch on and off during the scan. Therefore, by definition, if the magnetic field is switched on and off, then it is pulsed.

Dave
Click to expand...

MRI machine uses a constant (superconducting) magnetic field and uses pulsed radio frequency to flip the hydrogen protons that are aligned with the external field. The relaxation of these flips is measured, either T1 or T2 and thats the information you get as the relaxation differs between tissue types. There are coils for both sending out the RF pulses and reciving the returning pulses (also coils for shiming the magnitic field too). If the magnetic field was not homogenius it would cause problems because not all protons would be subjected to the same external field. I should point out my PhD is in Nuclear Magnetic Resonance lol
 
Well, I certainly can't argue with that, and I bow to your undoubtedly qualified knowledge in this field. Thank you for taking the time to explain the theory behind it, one never stops learning in life. :)

It is confusing when you read that the Magnetic Coils are switched on and off, not to think that the magnetic field is collapsed and then re-generated in a cyclic manner, which to my limited understanding is pulsing.

However, I now know better.

Dave
 
Last edited:
MRI uses an exceptionally strong magnet and radio frequency waves, and they subject your brain to this :eek: amazing they do all this, and without damage to the brain! ( we hope )
 
MRI machines for humans have lower field strengths than those for small animals or for liquid samples. average for a human sized MRI will be around 3T, large bore around 7T while protein NMR will be at least 14T ( our NMR machine at Glasgow Uni is a 14T 600mhz Bruker ultrashield) larger the magnet the bigger it is and the more is costs to run. 800mhz and up machines are a different design. stronger the magnet the more resolution you get but the stronger the RF pulses have to be to flip the protons.
 
14 Teslas, that is some magnetic field. Thank goodness the field falls of rapidly with distance. Inverse square law?.

Dave
 
jonbeeza said:
But this was early morning when I saw her put the butties and juice in the room, by mid day they could have done a good few X-Rays.
Click to expand...

She's using the x-ray machine as a low-power microwave to heat up her lunch. That's why they have to take so many x-rays, otherwise she'd have a lukewarm cheese sandwich instead of a lovely hot toasty.
 
It's generally accepted that taking a long-distance flight gives you more ionising radiation than you'd normally achieve in a lifetime from diagnostic x-rays. Radiographers try to limit the amount of radiation you get, CT being somewhat higher, but I'd have thought it beneficial to get a proper diagnosis of the problem and therfore, hopefully, better treatment. As for the stuff about irradiated lunches ... well, no comment! I guess it may preserve it better until the day after :-)
 
Strappy said:
She's using the x-ray machine as a low-power microwave to heat up her lunch. That's why they have to take so many x-rays, otherwise she'd have a lukewarm cheese sandwich instead of a lovely hot toasty.
Click to expand...
andyo said:
As for the stuff about irradiated lunches ... well, no comment! I guess it may preserve it better until the day after :)
Click to expand...

Forgot all about Microwaved food, but there again that's not radiation is it :)
 
jonbeeza said:
Forgot all about Microwaved food, but there again that's not radiation is it :)
Click to expand...

That's non-ionising radiation John, which is a different 'animal' to ionising radiation.

Near Ultraviolet, visible light, micro waves, and down through the radio frequency spectrum, are all examples of non-ionising radiation.

Far ultraviolet, X-Rays, Gamma Rays, and radiation from radio active decay, are all examples of ionising radiation.

So, rest easy John. :)

Dave
 
DaveS2 said:
That's non-ionising radiation John, which is a different 'animal' to ionising radiation.

Near Ultraviolet, visible light, micro waves, and down through the radio frequency spectrum, are all examples of non-ionising radiation.

Far ultraviolet, X-Rays, Gamma Rays, and radiation from radio active decay, are all examples of ionising radiation.

So, rest easy John. :)

Dave
Click to expand...


OK will do :)
 
This might be of some interest

radiation.png
 
umm yes microwaves are radiation :p check out an electromagnetic spectrum chart on google for the definitive list :)

when my doc suspected arthritis in me she said a blood test would show it

I recently had a suspect broken tail bone but they didn't x-ray it as the outcome would be the same

a little known fact is that body scanners can cause cancer, as can mammograms but they say the risk is minuscule

I did my year out at uni in a medical physics dept and I avoid all x-ray type things as much as possible. dentists are the worst - they love giving you x-rays.
 
sturisoma said:
umm yes microwaves are radiation :p check out an electromagnetic spectrum chart on google for the definitive list :)

when my doc suspected arthritis in me she said a blood test would show it

I recently had a suspect broken tail bone but they didn't x-ray it as the outcome would be the same

a little known fact is that body scanners can cause cancer, as can mammograms but they say the risk is minuscule

I did my year out at uni in a medical physics dept and I avoid all x-ray type things as much as possible. dentists are the worst - they love giving you x-rays.
Click to expand...

The missus says I am paranoid, but I just don't like the idea of being subjected to radiation. :eek:
 
I don't think you're being paranoid :)
 
You must log in or register to reply here.
Back
Top