Topic 2- X-rays and ECGs Flashcards
KE=
e (electronic charge) x V (voltage)
describe thermionic emission
hot filament (cathode) releases electrons and the anode is a metal target, x-rays are emitted by the anode
I (current)=
N (number of particles per second) X q (charge on each particle)
x-rays can harm the body through
ionisation
x rays have a very high frequency and therefore
high energy
x rays have enough energy to ionise molecules in
living cells
intensity of radiation depends on distance from source so
if you move twice as far away, 1/2 squared = 1/4
thickness of materials affects
x-ray absorption
the more dense,
the more radiation is absorbs
used to reduce people’s exposure to x-rays
lead and concrete
x ray tube casing is used
to absorb x-rays
the thicker the material,
the greater the reduction of x-ray intensity passing through to other side
fluoroscopes use X-rays to create
moving images of a patient’s insides
fluoroscopy is used to diagnose problems with
the ways organs are functioning
CAT scans produce images of a
2D slice through the body
describe CAT scan
X-ray beam rotates around the body and is picked up by thousands of detectors, computer works out how many x-rays are absorbed and creates image. can also make 3D image by layering
CAT scans are often used to look for
tumours and cancer
x-rays for imaging are often used because
the benefits outweigh the risks
muscles cells can generate
potential differences
resting potential of a muscle cell is about
-70 mV
action potential is about
40mV
Electrocardiographs measure the
action potentials of the heart
frequency=
1/time period
a pacemaker is a device used to
regulate heart beat
pulse oximeters use light to check
the % of oxygen in the blood
blood rich in oxgen is
bright red
how the pulse oximeter works
transmits 2 steaks of red and infrared light and detects them at other side
