Scientists have now discovered rays with even shorter wave-lengths, which they call gamma rays, and which can pass
through even more solid substances than X-rays can.
As well as being used for taking photographs, X-rays are also used for treating diseased parts of the body to kill
So today doctors can find out by X-rays whether a patient has tuberculosis, for example, or cancer, in time to be
able to cure it, and then use the X-rays to destroy the cancer.
This is why people are encouraged to have X-rays taken in the mass radiography units which go to schools and
factories and such places.
X-rays are also used for studying many other things as well as human bodies.
Engineers use them, for example, to find out how metals are made up, to check whether they will be strong enough
for their purpose and whether there are any flaws in them.
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