Transcript Work - science

Cnoncet
• Lsat lseosn we rveesid wevas. Taody wl’el
lrean aubot X-ayrs. Tiher pouodctirn, uess
and percuatoins wehn uisng tehm.
• Darw a dgaiarm of the eelmocratngeitc
septcurm on the withdorebas and lbael
werhe X-yars are. Wtire dwon two denrags
of X-arys and percuatoins to tkae. Tlak to
yuor tblae aobut how you tinhk tehy may
be poudcred.
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20 July 2015
X-Rays
Objectives
Be able to define keywords in the topic and select
appropriate equations.
HSW: AF2 – Understanding the applications and implications of science
Used before in: P1 - waves
Will use again in: lesson 2
PLTS: Team workers – Work collaboratively with others.
Used before in: p2
Will use again in: lesson 2
Keywords
Reflection, refraction, diffraction, transmission, sound, light,
mechanical, electromagnetic spectrum, frequency, period,
wavelength, incident ray, wave speed, echo
Outcomes
• ALL MUST be able to state 3 properties
of X-Rays, 2 uses and 3 precautions we
can take around them.
• MOST SHOULD be able to describe
how X-Rays are formed and their
applications.
• SOME COULD explain the dangers of XRays and compare them to other parts
of the EM-spectrum to explain why we
use X-Rays in the way we do.
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Amazing survival
• http://www.youtube.com/watch?v=_Lg4Hs
5X6JA
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How are X-rays produced?
X-rays are created when high-energy electrons suddenly lose energy. X-rays are
produced artificially using a X-ray tube.
high
voltage
anode
cathode
lead
shielding
tungsten
target
X-rays
Electrons from the hot cathode are fired at the tungsten target at high speed. When
these high-energy electrons strike the
target, some of their energy is changed into X-rays.
Use of X-Rays in diagnosis
X-Rays are very penetrating and can
pass through the body.
They are absorbed more by dense
materials
such as bone (so they are useful for
checking the skeleton)
and particularly metal.
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Example X-Rays
Two views of a finger on the right
hand. The dislocation can be
clearly seen at the joint.
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Metal absorbs XRays, so
shows up
much more
clearly than
bone
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Skull (with a fracture
visible on the
original)
Note the fillings in
the teeth
Computer
enhancement
allows the soft
to be seen
Page tissue
136
CAT Scan
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Multiple X-Ray
images can be
combined to
give 3D images
This is called a
CAT scan.
Computerised
Axial
Tomography
(tomos – Greek
for slice)
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video
What do X-rays do to cells?
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X-Ray precautions
Because X-Rays can damage cells we need
to minimise exposure by:
only using X-Rays when necessary,
shielding other parts of the body,
focussing the X-Rays,
using short exposure times
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Demonstration
• You will now be given some tasks to do in
your groups to show your understanding
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Card Sort
• Sort the cards into 4 piles:
Properties
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Medical Uses
Dangers
Precautions
X-Rays
Properties
Medical Uses
Dangers
Precautions
Travel at the
speed of light
Measure bone
density.
X-Rays can kill
damage and kill
living cells
Use lead screens
to block unwanted
rays
Have high energy,
high frequency
Examine dense
materials in the
body like bone
X-Rays can cause
cancer
Wear film badges
to monitor
exposure times
Have very short
wavelength
CAT scans give
3D images of the
body.
Only use when
entirely necessary
Cause ionisation
– by causing
electrons to split
away from atoms
Highly focussed,
energetic beams
can be used to kill
cancer cells
Focus the beam
They are
absorbed by
dense materials,
such as bone or
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metals.
Minimise the
exposure time
Memory Board
• You have 1 minute to examine the
diagram of how X-Rays are produced.
• Then you must add the labels and
describe in your own words how X-Rays
are produced.
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How are X-rays produced?
X-rays are created when high-energy electrons suddenly lose energy. X-rays are
produced artificially using a X-ray tube.
high
voltage
anode
cathode
lead
shielding
tungsten
target
X-rays
Electrons from the hot cathode are fired at the tungsten target at high speed. When
these high-energy electrons strike the
target, some of their energy is changed into X-rays.
How are X-rays produced?
Think Pair Share
• The last test!
• Your teacher will ask some questions. You
have 1 minute in silence to write the
answer.
• 40 seconds to discuss it with your partner
• 20 seconds to talk about it with your group
and hold up the best answer when your
teacher says “show me”
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• Explain why they are used to check
broken bones.
• How can X-Rays be dangerous?
• How else do we use waves in
medicine? Compare X-Rays to other
medical uses of waves to explain why
we use X-Rays in the way we do.
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Pop Quiz – 1 – 8 in back of book
1)
2)
3)
4)
5)
6)
State 3 properties of X-Rays
State 3 uses of X-Rays
State 1 danger of X-Rays
State 3 precautions to take around X-Rays
Describe how X-Rays are formed
Describe how X-Rays can help us see
broken bones
7) Explain the dangers of X-Rays
8) Explain why would doctors not use X-Rays
to monitor unborn foetuses.
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Tell me two things...
(for each)
• that you have done well this session
• that you know now that you didn’t
know at the start
• that you could do better next time
• that you would like to know more
about
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