Unit 3

AQA GCSE Physics

1. X-rays 2. Ultra-sound 3. Lenses 4. The Eye 5. Other Applications using Light

Medical Applications of Physics

1. X-Rays

What are X-rays?

• X-rays are part of the electromagnetic spectrum.

• They have a very short wavelength and cause ionisation.

What is ionisation? Do X-rays have a large or a small frequency?

What are X-rays used to do?

• X-rays are used to diagnose and treat some medical conditions.

Bone Fractures

Dental Problems – Wisdom Tooth

Killing Cancer Cells

Properties of X-Rays

• They are absorbed by metal and bone. • They are transmitted by healthy tissue.• They affect photographic film in the

same way as light. • Their wavelength is the same order of

magnitude as the diameter of an atom.

Photographic Film Image

Charge Coupled Device (CCD)• X-rays can be formed

electronically using CCDs.

• They are silicon chips that are divided up into millions of identical pixels.

• CCDs detect X-rays and produce electrical signals which are used to form high resolution images.

CT Scans

• A computerised tomography (CT) scan, also known as a CAT scan, uses X-rays and a computer to create detailed images of the inside of your body.

CT Scan Examples

Whole Body CT Scan – with contrast media

• http://www.youtube.com/watch?v=1DEkae94jDU

Patient videos for patients

• What to expect from a CT scan. http://www.youtube.com/watch?v=e-QwyZVMLSo

• Patient education video. http://www.youtube.com/watch?v=T-kGrOJ9BK4

Precautions when using X-ray machines and CT machines

• Radiographers – Wear lead aprons – Stand behind a lead screen – Leave the room

And……… Lead is used to shield the parts of the body that aren’t being scanned. And……..exposure time is kept to a minimum.