Radiation Uses Flashcards
(2) ) Explain which of these frequencies of ultrasound can be used to scan organs
deep inside the body
• 2 MHz (1) and any one from: • has a higher intensity inside tissue (1) • less energy absorbed (1) • less attenuation (1) • penetrates furthest /deepest (1)
(6) Compare the use of electromagnetic radiation in endoscopes and in one other
diagnostic device.
Diagnostic devices
• CAT scanners
• Fluoroscopes
• Thermal imagers / IR thermometers
• Pulse oximeters
• PET scanners
• X-ray machines
• Gamma cameras
Link to electromagnetic radiation
• Endoscopes use TIR of light in optical fibres
• CAT scanners X- rays and computer to generate 3D
images
• Fluoroscopes use X- rays and a video camera
• Thermal imagers use infrared emitted by a body
• IR / red LEDs used to measure oxygen levels
• PET scanners detect radiation emitted by electronpositron
annihilation
• Gamma cameras detect gamma rays from radioactive
sources
Other factors for comparison
• Safety
• Ease of use
• Frequency / wave length
• Intensity
• Penetration
• Ionising / non-ionising
(1) Iodine-123 is used as a radioactive tracer to diagnose thyroid problems.
This tracer must have a half-life of
a few hours
(3) Radium-223 has a half-life of 11.4 days and emits alpha radiation.
Explain why radium-223 is suitable for use inside the body to treat cancers.
MP1 alpha/the radiation is (highly) ionising (1) MP2 the radiation destroys cancers/tumours (1) MP3 alpha particles/ do not penetrate very far in the body/inserted close to the cancer (1) MP4 half-life is long enough for the treatment to take effect (1) MP5 half-life is short enough so that the pellets do not need to be removed (1)
(2) Radiotherapy is often used for palliative care when cancers are incurable.
Explain how using radiotherapy in this way is helpful to patients.
reduces the size of tumours/cancers (1) reduces pain/ relieves symptoms / extends life expectancy / Improves quality of life (1)
(2) Explain why a CT scan of the chest gives a much higher dose of radiation than
a chest X-ray.
CT scan lasts much longer / X-ray short exposure (1) CT scan is many X-ray (slices) (1) The intensity of radiation for CT scans is higher than for normal Xrays (1)
(2) Justify the use of medical procedures which give patients large doses of radiation.
appreciation that there would be risks (1) ONE from:- non-invasive/ not painful (1) OR more accurate/better/earlier diagnosis (1) OR life-saving/ provide cure (1)
(1) Which of these is correct for red light and infrared radiation in terms of wavelength?
Red light has a shorter
wavelength than infra-red.
(6) The diagram shows an electrocardiogram (ECG) trace with values given for the
horizontal and vertical scales used.
Describe how the characteristic shape of the curve and the distance between
peaks relates to the way the heart works.
standard labelling for electrocardiogram signal
pattern shows heart action
all shapes are the same so no heart irregularity
patterns shows the parts of the heart pumping blood
pattern produced reflects the electrical activity of the heart
changes in the shape can show weaknesses in different
parts of the heart ( heart attacks)
the trace shows potential differences across different parts
of the heart when the muscles contract and relax
action potentials ( electrical signals) originate in the right
atrium of the heart
P wave shows muscle contraction spreading through the
atria (depolarisation)
QRS shows the ventricles contracting to pump blood to
lungs and the rest of the body
T wave is repolarisation when ventricles fill with blood
Distance between peaks
shows heart rate.( 60 to 90 beats per minute considered
normal)
the time for one beat of the heart is represented by the
distance between the peaks (could be shown on diagram)
one beat is 0.78s to 0.82s
frequency of 1.25Hz to 1.3 Hz
beats per minute 74 to 80
