3.1 (P1) Medical Application

Question 1

What are general properties of X-rays?

Answer 1

Part of the electromagnetic spectrum
High frequency
Short wave length (0.01 - 10 nano meters or diameter of an atom)
Very ionising

Question 2

What are properties of X-rays in medical application?

Answer 2

Transmitted by healthy tissue (passes through)
Absorbed by denser material - bone and metal

Affects photographic film the same way as light

Question 3

What are some uses of X-rays?

Answer 3

Identifying broken bones/fractures
Dental problems
Killing some cancer cells (with wide rotating beam focused at the centre)

Question 4

What is a CCD? How does it work?

Answer 4

Charged-couple device

They detect X-rays converting them into light
Then creates electronic signals to form high resolution digital displays

Question 5

What is a CT scan used for and do?

Answer 5

Uses X-rays to produce high resolution images or hard and soft tissue

Many 2D images are taken and built up to make a 3D image of inside the body

Question 6

What precautions should a doctor take when using X-rays?

Answer 6

Wear a lead apron

Wear a film badge and leave the room when exposed for too long

Question 7

What precautions do we take for the patients?

Answer 7

Don’t take too many close together
Cover areas not needed with lead
Check if they are pregnant (harmful to the baby)

Question 8

What is ultrasound?

Answer 8

A sound with a higher frequency than we can hear

Question 9

What is the range of human hearing?

Answer 9

20Hz - 20,000Hz

Question 10

What is the frequency of ultrasound?

Answer 10

20,000Hz +

Question 11

What happens to ultrasound waves at a boundary of different density?

Answer 11

They get partially reflected

Some refraction

Question 12

What can the time for the reflection tells us?

Answer 12

Determine how far away the boundary is

Question 13

What do you remember when calculating the boundary distance?

Answer 13

Divided by 2 as the reflection went there and back

Question 14

What are medical uses for ultra scans?

Answer 14

Prenatal scan of foetus
Breaking down kidney stones (high energy wave)
Investigating blood flow to organs
Finding fluid in stomach

Question 15

What is an industrial use for ultrasound?

Answer 15

Sonar to find fish

Checking manufactured objects

Question 16

What is and advantage and disadvantage over X-rays?

Answer 16

Advantage: Aren’t ionising so safer

Disadvantage: low resolution image

Question 17

What is the refractive index?

Answer 17

The change in direction of light when light passes through two different transparent densities

Question 18

In refractive index:

The denser the media…

Answer 18

The slower the speed of the light

Question 19

What nemonic is helpful to remember direction of light in refractive index?

Answer 19

TAGAGA

Towards
Air
Glass
Away
Glass
Air

Question 20

What is the unit of refractive index?

Answer 20

No unit as it’s a ratio

Question 21

What is the critical angle?

Answer 21

A special name given to the angle of incidence when the light is refracted along the edge of the boundary

Question 22

What does an endoscope allow?

Answer 22

You can look inside a patients body without having to cut them open (keyhole surgery)

Question 23

How does an endoscope work?

Answer 23

It contains optic fibres (thin flexible glass fibres)

Visible light is sent along the fibres by total reflection

Question 24

What else can you use light for in medicine?

Answer 24

As a laser for:
Cutting
Cauterising 
Burning
Eye surgery

Question 25

How does a laser help in laser eye surgery?

Answer 25

Vaporises some of the cornea to change it’s shape

Changing the focusing ability