One option is shouting.
No, not really. But high frequency sound – ultrasound – can be projected into the body, and by analysing the echo that comes back we can see things like organs or even babies. The great advantage of ultrasound is that its quick, safe, cheap (well, relatively), and gives real-time images of things moving, beating, pulsing or kicking.
Getting more advanced, technologies such as MRI and PET scans can provide clear and tremendously detailed images of our organs, including the brain.
Magnetic Resonance Imaging uses a strong magnetic field and radio waves to produce images. It’s particularly good for looking at neurons and muscle. Try out this game to learn more, from – of all places – the official Nobel Prize website. No, really.
A Positron Emission Tomography scan uses positrons – a type of antimatter – to image the body whilst all the bodily functions are working away. This allows doctors to assess which bits are working correctly. Yes, the NHS routinely uses antimatter to help patients.
As you’d expect, the Institute of Physics have more notes on MRI and PET scanning techniques.