Question 1

What is the difference between an X-ray, a CT scan and an MRI?

Accepted Answer

They produce images using completely different physics, which determines what each one shows well.

**X-ray.** A beam of ionising radiation passes through the body onto a detector. Dense tissue — bone, metal — absorbs more and appears white; soft tissue and air absorb less and appear darker. The result is a **single flat projection**, with everything along the beam path superimposed.

**Best for:** fractures, chest imaging, dental work, foreign bodies. **Fast, cheap, widely available, low radiation dose.**

**Limitations:** poor soft tissue detail, and overlapping structures.

**CT (computed tomography).** Also X-rays, but the tube rotates around the patient taking many projections, and a computer reconstructs **cross-sectional slices** that can be assembled into a 3D model.

**Best for:** trauma assessment, internal bleeding, stroke, lung and abdominal imaging, complex fractures, and anything needing a rapid detailed answer. A CT head scan takes seconds, which matters enormously in emergencies.

**Limitations:** a **significantly higher radiation dose** than plain X-ray — often equivalent to hundreds of chest X-rays — so it is used where the diagnostic benefit justifies it. Soft tissue contrast is good but below MRI.

**MRI (magnetic resonance imaging).** **No ionising radiation at all.** A powerful magnetic field aligns hydrogen nuclei in the body's water and fat; radio pulses knock them out of alignment, and the signal they emit returning to alignment is measured. Different tissues have different signal characteristics.

**Best for:** soft tissue — brain, spinal cord, ligaments, tendons, cartilage, muscle, and many tumours. Far superior contrast between soft tissues than anything else.

**Limitations:** slow (often 20–60 minutes), expensive, noisy, and enclosed, which is difficult for claustrophobic patients. **Metal is a serious safety issue** — some implants, pacemakers and metal fragments are contraindications, which is why the safety questionnaire is not a formality.

**Ultrasound** is a fourth option, using sound waves, with no radiation and real-time imaging.

Question 2

How is cancer actually diagnosed and staged?

Accepted Answer

Through a sequence that moves from suspicion to tissue, because only examining the cells themselves gives a definitive answer — scans and blood tests can suggest, but they cannot confirm. The usual

Question 3

Why is back pain treated so differently now?

Accepted Answer

Because the evidence changed substantially, and the old model — rest, scan, find the damage, fix it — turned out to make outcomes worse for the great majority of cases. What is now understood: Most

Question 4

What is osteoporosis, and who should be assessed for it?

Accepted Answer

A condition in which bones lose density and structural quality, becoming fragile enough to break from a fall or force that would not normally cause a fracture — and its defining feature is that it is

Question 5

What actually happens at an eye test, and what does it check for?

Accepted Answer

Far more than whether you need glasses — a sight test is also a health examination, and it detects conditions with no symptoms at a stage where treatment still works. What is actually checked: Visual

Question 6

How does a doctor actually reach a diagnosis?

Accepted Answer

Mostly by listening — the history gives the diagnosis in a large majority of cases — followed by examination and, only then, tests to confirm or exclude. The popular image of diagnosis as a puzzle

Question 7

How does organ donation actually work?

Accepted Answer

Through a tightly time-limited process that depends on how someone dies as much as on whether they consented — which is why donation is possible far less often than people assume. The constraint

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