Radiation (in treatment and medicines)

Question 1

What is radiation?

Answer 1

Radiation refers to any form of energy carried by waves or particles and originating from a source.

Question 2

What are the two common types of radiation?

Answer 2

• a wave

- a particle

Question 3

What are 5 examples of using radiation for diagnosis?

Answer 3

• X-rays
• CAT scanners
• PET scanners
• Endoscopes
• Ultrasound

Question 4

What are x-rays?

Answer 4

A form of electromagnetic radiation which is used to take images of broken bones and some soft tissues.

Question 5

What are CAT scanners?

Answer 5

CAT stands for Computer Axial Tomography. It generates a 3-D image from a large series of two-dimensional X-ray images.

Question 6

What are PET scanners?

Answer 6

Radiopharmaceuticals (radioactive chemicals) are either injected or swallowed. External detectors called gamma cameras take images of the radiation emitted.

Question 7

What are endoscopes?

Answer 7

An endoscope is a medical device which is used to look inside the body - commonly the reproductive and digestive systems, and the urinary and respiratory tracts. One bundle of fibre optics carries light to the object and another returns an image for the doctor to view.

Question 8

What is ultrasound?

Answer 8

Ultrasound has a frequency higher than human hearing. Some tissues and organs reflect these waves back and the time taken for them to return is used to measure their depth. It is often used to create images of unborn babies, but it is also used to create images of tendons, muscles joints and some internal organs.

Question 9

What happens to the intensity of radiation the further out an object is?

Answer 9

The intensity of radiation received by an object decreases the further out the object is.

Question 10

What is intensity?

Answer 10

The strength of light arriving at a certain point.

Question 11

What happens to a wave the further it travels?

Answer 11

A wave will get weaker the further it travels.

Question 12

What is the equation for intensity?

Answer 12

intensity = power (watts) / area (m2)

Question 13

What is the main law of reflection?

Answer 13

angle of incidence = angle of reflection

Question 14

What is refraction?

Answer 14

When waves enter a medium in which they travel more slowly, the wave’s direction of travel changes.

Question 15

What direction do rays travel when they enter a medium in which they travel more slowly?

Answer 15

Rays travel towards the normal when they enter a medium in which they travel more slowly.

Question 16

What direction do rays travel when they enter a medium in which they travel faster?

Answer 16

Rays travel away from the normal when they enter a medium in which they travel faster.

Question 17

What happens when light enters a more dense medium?

Answer 17

When light enters a more dense medium, it slows down.

Question 18

What are converging (convex) lenses?

Answer 18

Thicker at the centre.

Question 19

What are diverging (concave) lenses?

Answer 19

Thinner at the centre.

Question 20

What happens during refraction in a converging lense?

Answer 20

The rays of light are refracted inwards and meet at the focus, F. The image formed is real.

Question 21

What happens during refraction in a diverging lense?

Answer 21

The rays of light are refracted outwards. A virtual image is formed.

Question 22

What is Snell’s law?

Answer 22

sin (angle of incidence) ÷ sin (angle of refraction) = refractive index of air ÷ refractive index of water
or
sin (angle of incidence) ÷ sin (angle of refraction) = constant

Question 23

What is the lenses equation?

Answer 23

1 ÷ f (focal length) = 1 ÷ u (object distance) + 1 ÷ v (image distance)

Question 24

What is an optical fibre?

Answer 24

An optical fibre is a long, thin, transparent rod made of glass or plastic. Light is interally reflected from one end to the other, making it possible to send large chunks of information

Question 25

What are the uses of optical fibres?

Answer 25

Optical fibres can be used for communications by sending electrical signals through the cable. The main advantage of this is a reduced signal loss and endoscopes use this principle.

Question 26

What is ultrasound?

Answer 26

Ultrasound is the region of sound above 20,000Hz – it can’t be heard by humans.

Question 27

What are the two uses of ultrasound?

Answer 27

• prenatal scanning

- medical treatment e.g. treating kidney stones by using high intensity ultrasound