Uses of X-rays and Gamma Rays

Seeing inside objects with X-rays

X-rays are electromagnetic waves that can travel through some materials but are absorbed more strongly by others. This difference lets us observe an object's internal structure without cutting it open. An X-ray source sends radiation through the object towards a detector. Where more X-rays get through, the detector receives more radiation; where more are absorbed, it receives less. These differences form an image.

In a medical X-ray, soft tissue lets more X-rays through than bone. Bone therefore produces a distinct region on the image, helping a clinician examine structures such as a skeleton. Airport security scanners use the same broad idea to reveal objects inside luggage: their contents affect how much X-ray radiation reaches the detector.

Gamma rays: sterilising and treating disease

Gamma rays are another high-frequency type of electromagnetic radiation. They are penetrating and can damage living cells. Used in controlled conditions, that damage has valuable applications. Gamma rays can kill microorganisms in food, helping it last longer and reducing the risk of infection. They can also sterilise medical equipment; their ability to penetrate packaging means equipment can be treated while sealed.

Gamma rays have two different roles in cancer care. For detection, a radioactive tracer in the body emits radiation that can be detected from outside, helping to locate a tumour or investigate what is happening inside the body. For treatment, beams of gamma rays are directed at a tumour to damage or kill cancer cells. The treatment is planned to limit exposure of surrounding healthy tissue.

Why their use is controlled

X-rays and gamma rays are ionising radiation: they can remove electrons from atoms. They can also damage body cells or cause mutations. Their useful effects therefore have to be balanced against the risk of unnecessary exposure. An X-ray image uses radiation to gather information; gamma-ray treatment deliberately uses its cell-damaging effect. The purpose and the way the radiation is used are different.

X-rays

Different materials absorb different amounts of X-rays, producing an image of internal structure. Uses: medical X-rays and airport security scanners for luggage.

Gamma rays

Their penetration and ability to damage cells allow sterilisation of food and medical equipment. In cancer care, an emitting tracer helps detect disease; directed gamma-ray beams treat a tumour.

Shared caution

Both are ionising and can damage cells or cause mutations, so unnecessary exposure is limited.