# A patient swallows a barium meal before an X-ray examination of their digestive system. Explain why barium is used and how it allows the digestive system to be imaged, including why it would not normally be visible on an X-ray without the barium.

> AQA A-Level Physics (7408) — 3.10.5 X-ray Imaging · Explain · 5 marks

> Barium sulfate is a substance that is given to patients before certain X-ray examinations. It passes through the digestive system without being absorbed into the body.

## Mark scheme (5 marks)

1. X-rays are absorbed (or transmitted) differently by different materials / X-rays are absorbed more by denser materials
2. Soft tissue / the digestive system absorbs X-rays weakly / by a similar amount to surrounding tissue, so it does not show up on the X-ray image
3. Barium absorbs X-rays strongly / more than soft tissue
4. Where barium is present, fewer X-rays reach the detector / film, producing a (bright/white) shadow or contrast on the image
5. This allows the shape / outline / any abnormalities of the digestive system to be seen / imaged

## Key terms

- [X-ray](https://www.gradenine.co.uk/glossary/x-ray)

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-patient-swallows-a-barium-meal-f4ff1e20) · Published by Druglandscape Ltd.