3.1 (P1) Medical Application Flashcards
What are general properties of X-rays?
Part of the electromagnetic spectrum
High frequency
Short wave length (0.01 - 10 nano meters or diameter of an atom)
Very ionising
What are properties of X-rays in medical application?
Transmitted by healthy tissue (passes through)
Absorbed by denser material - bone and metal
Affects photographic film the same way as light
What are some uses of X-rays?
Identifying broken bones/fractures
Dental problems
Killing some cancer cells (with wide rotating beam focused at the centre)
What is a CCD? How does it work?
Charged-couple device
They detect X-rays converting them into light
Then creates electronic signals to form high resolution digital displays
What is a CT scan used for and do?
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
What precautions should a doctor take when using X-rays?
Wear a lead apron
Wear a film badge and leave the room when exposed for too long
What precautions do we take for the patients?
Don’t take too many close together
Cover areas not needed with lead
Check if they are pregnant (harmful to the baby)
What is ultrasound?
A sound with a higher frequency than we can hear
What is the range of human hearing?
20Hz - 20,000Hz
What is the frequency of ultrasound?
20,000Hz +
What happens to ultrasound waves at a boundary of different density?
They get partially reflected
Some refraction
What can the time for the reflection tells us?
Determine how far away the boundary is
What do you remember when calculating the boundary distance?
Divided by 2 as the reflection went there and back
What are medical uses for ultra scans?
Prenatal scan of foetus
Breaking down kidney stones (high energy wave)
Investigating blood flow to organs
Finding fluid in stomach
What is an industrial use for ultrasound?
Sonar to find fish
Checking manufactured objects
What is and advantage and disadvantage over X-rays?
Advantage: Aren’t ionising so safer
Disadvantage: low resolution image
What is the refractive index?
The change in direction of light when light passes through two different transparent densities
In refractive index:
The denser the media…
The slower the speed of the light
What nemonic is helpful to remember direction of light in refractive index?
TAGAGA
Towards Air Glass Away Glass Air
What is the unit of refractive index?
No unit as it’s a ratio
What is the critical angle?
A special name given to the angle of incidence when the light is refracted along the edge of the boundary
What does an endoscope allow?
You can look inside a patients body without having to cut them open (keyhole surgery)
How does an endoscope work?
It contains optic fibres (thin flexible glass fibres)
Visible light is sent along the fibres by total reflection
What else can you use light for in medicine?
As a laser for: Cutting Cauterising Burning Eye surgery
How does a laser help in laser eye surgery?
Vaporises some of the cornea to change it’s shape
Changing the focusing ability
