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X-rays, CT and MRI — what each one does
Three different machines, three different purposes, and three different sets of worries. Here is what each actually involves — and why we quite often tell you that you do not need one at all.
What people worry about
X-rays will give me cancer.
The dose from a limb X-ray is extremely small.
An X-ray of a hand, wrist, knee or foot delivers a very small dose — comparable to what you receive naturally from the environment over a short period simply by being alive.
That does not mean we should do them casually, and we do not. We order an X-ray when the result will change what we do. If it will not, we say so.
MRI is the best scan. I want an MRI.
MRI is the best scan for some things and the wrong scan for others.
MRI shows soft tissue — ligaments, discs, tendons, nerves. X-ray shows bone and alignment. CT shows bone detail in three dimensions.
And there is a real problem with scanning too early: MRI finds disc bulges, meniscal tears and rotator cuff changes in very large numbers of people who have no pain whatsoever. A scan done too soon often finds something that was already there, frightens you, and leads to treatment you never needed. That is why we wait until the answer would change something.
I am claustrophobic. I will not manage an MRI.
Tell us beforehand. There is always something we can do.
Options include lying feet-first where the part allows, an open or wide-bore scanner, a mild sedative arranged in advance, and having someone stay in the room with you.
What does not work is turning up and hoping. Say it when the scan is booked.
The MRI noise means something is wrong with the machine.
It is supposed to be loud.
The knocking, banging and buzzing are the magnets switching. You are given earplugs or headphones, and many centres will play music.
You will also be given a buzzer to press. Pressing it stops the scan — you are never trapped.
If the scan is normal, does that mean the pain is in my head?
No. It means the scan could not see the cause.
A great many real and painful conditions show nothing on a scan — muscular back pain, tendon pain, nerve irritation, early inflammatory disease.
A normal scan is useful information, not a verdict on you.
What actually happens
X-ray 2–5 minutes total
You stand or lie against the plate, hold still, and it is done in a fraction of a second. Nothing touches you and you feel nothing at all.
CT scan 5–10 minutes
You lie on a table that slides through a wide ring — not a tunnel. It is open at both ends and you can see out. You hold still and breathe normally.
MRI: preparation 10 minutes
All metal off. You will be asked about pacemakers, metal implants and metal fragments in the eye — answer carefully, this is the safety check that matters.
MRI: the scan 20–45 minutes
You lie on a table that slides into the tube. Earplugs on, buzzer in hand. Loud knocking in bursts, with quiet gaps. Holding still is the only requirement.
Afterwards —
You go straight home and drive as normal, unless you were given a sedative — in which case someone must take you.
Guides for you
In your language, free to download. Each one is a short PDF you can keep on your phone or print.
Ready when you are.
Call either clinic during consulting hours, or send a WhatsApp message any time.