Medical Physics Questions

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  • Created by: IAN
  • Created on: 18-04-17 14:50
What is normal pulse rate?
60-80bpm
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What is the breathing rate?
12-15 breaths per minute
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Tidal Volume
400-500cm3
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Vital Capacity (Male)
4.8dm3
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Vital Capacity (Female)
3.1dm3
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Peak Flow
400 - 600dm3 min-1
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Normal Body Temperature
36.5-37.2°C
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Death Temperature
Below 25°C
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Hypothermia Temperature
32°C
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Fever Temperature
Above 37.2°C
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Heat Exhaustion
Above 38°C
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Death Temperature
Above 43°C
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18 Year old male Blood Pressure
120/80mm HG
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20 Year old male Blood Pressure
125/80mm HG
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40 Year old male Blood Pressure
135/85mm HG
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20 Year old female Blood Pressure
123/80mm HG
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40 Year old female Blood Pressure
133/85mm HG
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Why might a surgeon prefer to use a laser rather than a scalpel
Less scaring and no friction
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2 Precautions a surgeon would take when using a laser on a patient.
Not looking into the beam and wear appropriate eye protection.
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How to use a liquid in glass thermometer to get a accurate measurement.
1.Shake the thermometer ,2.Insert in the appropriate area,3.Leave for a few minutes,4. Remove and read the scale
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Two symptoms of hypothermia
Low energy and difficult thinking
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Why are shiny foil blankets effective?
Silver is a good reflector of heat radiation back into the body.
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What does MRI stand for?
Magnetic Resonance Imaging
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The Scientific principles of MRI scans.
MRI uses a NMR with strong magnetic fields to detect water molecules.
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2 advantages of using a MRI scan rather than a Xray
Less dangerous and a better contrast of soft tissue
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One disadvantage of using MRI rather than Xray
Expensive
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Why is the effective half life of a radioisotope always less than the physical half-life
Some radioactivity is removed from the body naturally.
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Function of the vacuum in the glass tube
Allows free movement of electrons
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Function of the cathode
Emits electrons
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Function of lead housing
Prevents Xrays escaping
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Function of anode
Attracts electrons
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What property of tissue determines how ultrasound respond to it
Density
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The equation which links velocity , frequency and wavelength of a wave
Velocity = Frequency * Wavelength
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The equation that links critical angle and reflective index
Sin C = 1/n
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How is an endoscope used to diagnose a stomach ulcer?
The endoscope gets swallowed and light is sent down and gets reflected back.
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How can a endoscope be used to treat a stomach ulcer?
A lazer gets sent down an endoscope then a second endoscope is sent down the check its position.
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Why would it not be sensible to give patients a manual sphygmomanometer to use themselves at home.
Too difficult to manipulate and training is needed.
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Why might a patients blood pressure be lower at home than being measured at a clinic
They will be less anxious at home
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One advantage of using a non invasive method of measuring blood pressure.
Quicker
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One disadvantage of using a non invasive method of measuring blood pressure.
Less accurate
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What is meant by the effective half life of a radioisotope?
The time for activity to half in the body
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Why is a patients core body temperature usually different from their skin temperature?
Skin temperature is affected by the surroundings and body temperature depends on a metabolic process.
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Why does a clinical liquid in glass thermometer have an inner tube with a much narrower bore than a laboratory thermometer>
Liquid travels further for each degrees rise in temperature and increases precision.
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What property of a thermistor changes with temperature?
Resistance
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Explain how resistance enables the thermistor to measure different temperatures.
Change = Resistance and causes change of voltage .The greater the change in temperature the greatest change in resistance.
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A factor which determines how precise the temperature reading given by an electronic thermometer is...
How much resistance changes for each degree in temperature.
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Explain why the radioisotope should emit only alpha or beta radiation.
Alpha/Beta is low penetrating while gamma penetrates out of the body.Alpha/Beta are ionising high ionising causes damage to cells.
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A advantage of using a radioisotope implant rather than external radiotherapy for treating soft tissues.
More effective targeting as it can be positioned in site
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A disadvantage of using a radioisotope implant rather than external radiotherapy for treating soft tissues.
The implant is less effective as time goes on because of decay.
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Why does keyhole surgeory usually have to make two incisions when carrying out keyhole surgery?
One incision for a light source and another incision for tools.
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The equation that links velocity ,frequency and wavelength of a wave
v = f • λ
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Why is a gel used?
To reduce differences in acoustic impedance and to avoid reflections into the skin.
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How should the size of specific acoustic impedance of gel compare with that of the skin?
Similar
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Main differences between Xrays and Ultrasound
Ultrasound waves are reflected - Xrays are transmitted
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What colour should the anode be in order to lose heat most efficiently?
Black
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If the anode becomes hot it will lose heat to the surroundings.Explain why this heat can only be lost as infrared radiation and not by means of conduction or convection?
The anode is in a vacuum .Particles are needed for conduction and convection to occur
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One reason why non-invasive methods are usually used to measure blood pressure even though invasive measurements give more accurate readings.
Less stress and less chance of false readings.
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Why are invasive methods likely to produce more accurate readings of blood pressure than non - invasive methods?
The probe is in contact with the blood.
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Why are X-rays able to detect breast cancer?
The absorbency of tissue density of cancerous is different
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What is thermography?
Detection of heat
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Suggest why thermography can detect breast cancer
Cancerous parts will have a different heat
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Why is thermotography safer than Xrays?
Thermotography is non-invasive while xrays are ionising and can damage cells.
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Why do doctors prefer Xrays than thermography
Safer,Better contrast of images ,familiar
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Ultrasound frequency
20.000 HZ
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Why must the glass walls of the bulbs of a clinical thermometer be as thin as possible?
To maximise the conditions of energy transfer
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What aspect of the design of a clinical thermometer maximises it's precision?
Narrow bore inner tube
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One use of EEG
Diagnose brain disorders
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What do ECG's measure in order to produce a trace of heart activity?
Electrical Impulses
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What is a spirometer used to investigate?
Breathing
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What is the heart doing when systolic pressure is recorded?
Heart Muscles Contracting
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What is the difference of blood pressure and pulse rate?
BP-How hard blood is forced through the body. PR- How many heart beats are given.
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What does half-life mean?
The time taken for half the radioactive nuclei present to decay
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What does organ affinity mean?
The radioisotope accumulates in a specific organ
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One ethical issue a doctor would have to consider before carrying out research on volunteer.
Volunteers must be aware of purpose of research
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When do alpha waves occur?
RELAXED
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When do beta waves occur?
MENTAL ACTIVITY
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When do theta waves occur?
STRESS
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When do delta waves occur?
SLEEPING
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State 2 reasons why a nurse chose an electrical thermometer than a liquid in glass clinical thermometer.
Readings can be stored & less human error in reading
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2 disadvantages electrical thermometer than a liquid in glass thermometer.
Battery will need changing & affected by surroundings
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Does the electronic clinical thermometer measure a suitable range of temperatures?
Yes -The human body is only alive within this range of temperatures
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Explain how the change in the thermistor’s properties enables it to be used to measure temperature.
Resistance with temperature - voltage varies with temperature
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What is a Radioisotope?
Radioactive material
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What is a medical tracer?
A substance which is inserted in the body which has its path traced
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Explain why technetium-99 is usually made on site, rather than being bought in and stored.
Half-life is very short and activity would drop too quickly
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State one disadvantage of using a medical tracer that has an organ affinity.
May accumulate in the wrong organ
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Cobalt 60 purpose
General therapy
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Iodine 131 purpose
Treating thyroid cancer
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Iridium 192 purpose
Implants to treat breast cancer
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Other than not being toxic, state one important property of a contrast medium.
High density
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Explain why a contrast medium has to be used when taking X-rays of the stomach.
Density too low to absorb X-rays / Depends on density difference
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Explain why X-ray imaging is more dangerous than endoscopy
X-rays are high frequency and can damage cells.
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State two reasons, other than its physical half-life, why technetium-99 is one of the most widely used medical radioisotopes.
Not toxic no organ affinity
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State one precaution that would be taken to protect the radiographer when X-rays are being used.
Lead apron
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Explain how the precaution of a lean apron protects the radiographer.
X-rays cannot penetrate lead
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State one precaution that would be taken to protect the patient when lasers are being used
Wear eye protection
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Why does wearing eye protection protects a patient
Stops lasers entering your eyes.
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Explain how a liquid-in-glass thermometer can detect and measure temperature changes.
1) Heat causes liquid to expand. 2)As it expands it moves up the tube. 3)How far it travels is the temperature.
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Which heat transfer mechanism is responsible for heat travelling through the outer glass casing of the thermometer into the liquid inside?
Conduction
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Explain why a liquid-in-glass thermometer is not the most effective way of measuring core body temperature with a person with hypothermia..
Slow & hard to read.
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What does the term half-life mean ?
The time it takes for the activity of a radioactive source to halve
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Explain why the effective half-life of a radioisotope is always less than its physical half-life.
The isotope is excreted from the body and biological process begins to occur.
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Radioisotopes used as implants must emit alpha or beta radiation, and should emit little or no gamma radiation.
Ability to damage cells, penetration and ionising
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Why is cladding used?
To stop light reflecting out through the sides of the fibre.
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How should the refractive index of the cladding compare with the refractive index of the glass used to make the internal fibres?
Lower
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What are xrays
High frequency electromagnetic waves.
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What is ultrasound
High frequency sound waves which are too high for humans to hear
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Expain why rotating the anode stops the anode overheating?
They have a slanted area to stop the electron mean melting it
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If the anode becomes hot it will lose heat to its surroundings. Which heat transfer mechanism is most likely to be used to do this?
This is the only way that heat can travel through a vacuum
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What does diagnosis mean?
To find out what is wrong
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State one precaution a radiographer takes to protect the patient who is receiving X-rays.
The lowest effective dose
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State one precaution a radiographer takes to protect themselves when they are X-raying patients.
Wearing a lead apron
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Stochastic
The extent of damage does not depend on dose
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Somatic
The person exposed experiences the damage.
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What does high contrast mean?
Clear Picture
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Explain why X-rays can produce high contrast images of bones but cannot produce high contrast images of soft tissue.
This depends on attenuation. Bone is high in attenuation and bone is not.Bone is more clear of attenuation.
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CAT & Xrays Advantages and Disadvantages
CAT scans show tissue damage and 3D images while xrays don't . CAT scans are expensive and give high radiation doses.
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State why it is sensible for a hospital to prepare an isotope than buying it in and storing it.
It will have a short life span which means its less hazardous.
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Explain why radioisotopes used as tracers must emit gamma radiation and should not emit any alpha or beta radiation.
Gamma penetrates through the body and is less damaging to the cells
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State and explain one advantage of using nanotubes rather than external radiotherapy to treat cancerous tumours.
They are more closely to the tumour-Radioactivity does not need to pass through to raech
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Advatage of using nanotubes rather than internal radiotherapy to treat cancerous tumours
No radioactivity involved- implants need to be in place for several weeks/months
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Advantage of using nanotubes rather than external radiotherapy to treat cancerous tumours
No surgery - less change of scraing
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State one advantage of using external radiotherapy rather than internal radiotherapy, surgery or nanotubes to treat cancerous tumours.
Nothing is physically inserted into the body
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2 sources of error in measuring radiation
Background radiation - Handle source with tongs
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What is critical angle
The angle of incidence for which the angle of refraction is 90°
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Explain why an endoscope needs to be made from glass that has a small critical angle
All rays at an angle greater than the critical angle will be totally internally reflected
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How should the refractive index of the cladding compare with the refractive index of the glass used to make the internal fibres?
Slower
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How would the endoscope be inserted into the body in order to do this?
Through the mouth and swallowed
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Another method than an endoscope to see if a patient has a stomach ulcer
Thermography- Endoscopy is preferred as it measures heat produced by desecrating.
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What is a coupling agent?
A gel applied to the skin to improve contact.
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Why is a coupling agent used when ultrasound scans are carried out?
To improve transition of sound
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Explain why patients are asked to keep still, while ECG traces are being taken.
Movement causes electrical impulses. Electrical impulses interfere with the trace
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Explain why blood pressure is represented by two numbers rather than one.
Measures are taken when the heart is contracting and when it is relaxing blood pressure is different at these times
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Why it is important for the glass used in an endoscope to have a small critical angle.
Endoscopes use total internal reflection.The lower the critical means light entering at a larger ranges of angles will be reflected.
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Give one example of a medical condition that could be diagnosed using an endoscope.
Stomach ulcers
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Describe and explain how the endoscope is used in the example you have given.
via an incision or swallowed to view a certain part.
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Pros and cons of CAT scans
Bones show clearly. X expensive, X High doses of radiation given out
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Similarities of MRI and CAT scans
Can be viewed as 3D images. Computers used to generate images
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Differences of MRI and CAT scans
MRI scans use magnetism, CAT scans use X-rays , CAT scans more dangerous than MRI scans
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Explain why this gel is used and why it is important that the gel has a value of specific acoustic impedance similar to the specific acoustic impedance of skin.
Prevents unwanted reflections as a difference would cause a reflection
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State what organ affinity means and explain why it has to be considered when choosing a radioisotope for medical use.
Radioscope may not go to a specific organ which causes problems so other organs can be used
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Suggest one further factor that has to be considered when choosing a radioisotope for medical use and explain why it is important.
A radioisotope that is toxic could poison the patient
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What aspect of the design of a clinical thermometer maximises its precision?
Narrow bore inner tube
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What do electrocardiograms (ECGs) measure in order to produce a trace of heart activity?
Electrical Impulses
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What is the heart doing when systolic pressure is recorded?
Heart muscles contracting
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Describe the difference between blood pressure and pulse rate.
BP-How hard blood is forced around the body. PR-How many heart beats are given.
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Explain why blood pressure measurements are taken at the patient’s upper arm, but the pulse rate is measured at the patient’s brachial artery or at the wrist.
Blood pressure taken level with the heart so values will be the same.
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State and explain one advantage of using an invasive method of measuring blood pressure.
More accurate-because directly in the bloodstream
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State and explain one disadvantage of using an invasive method of measuring blood pressure.
more chance of scaring because an incision has to be made.
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Why are CAT scans much more dangerous than standard X-ray imaging?
Higher doses
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How do CAT scans produce 3-dimensional images of the part of the body they are investigating?
Many images put together by a computer.
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A condition which is NOT likely to be investigated by endoscopy.
Blocked Artery
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State one property of iodine-131 that makes it suitable for use as a tracer and give one reason why that property is important.
Emits gamma radiation - tracers have to be detected outside the body
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State one reason why a radioisotope used as an implant should emit alpha or beta radiation only.
Must act at site
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Give one reason why using a laser is likely to minimise scarring.
Less friction with tissue than scalpel produces
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What lasers are and their effects on the body to explain why this is important.
Lasers are high energy light beams & Can cause eye damage
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State one advantage of using results from MRI scans rather than thermography to investigate blood flow to the feet.
Less heat emitted
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Explain why CAT scans are considered to be more dangerous than MRI scans
X-rays cause ionisation
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Which of the symptoms are NOT a symptom of hypothermia?
Fast heartbeat
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Which heat-transfer mechanism is the blanket designed to reduce most?
Thermal Radiation
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Why is the inside of the blanket coloured silver?
To reflect heat from the patient’s body back to the patient
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Why is the outside of the blanket coloured silver?
To prevent heat being emitted to the surroundings
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How should the refractive index of the cladding compare with the refractive index of the glass fibres?
The refractive index of the cladding needs to be slightly lower.
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List the equipment you would need for refractive index experiment.
Light source, protractor, rectangular glass sample, paper, pencil, ruler
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Why should the refractive index experiment be done in a darkened room?
To make the ray more clearly visible
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Why should you use large angles of incidence for refractive index experiment ?
To reduce errors
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State and explain one advantage of using traditional open surgery rather than keyhole surgery to treat a knee injury.
surgeon can see more clearly to see what is going on.
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State an.d explain one disadvantage of using traditional open surgery rather than keyhole surgery to treat a knee injury.
larger incision needed - so a longer recovery time
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State and explain one advantage of using thermography, instead of ultrasound, to diagnose a tumour on the kidney.
No possibility of any damage as its no invasive
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State and explain one disadvantage of using thermography, instead of ultrasound, to diagnose a tumour on the kidney.
Less accurate
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Explain how an X-ray image of a bone is formed.
Production of X-rays in an X-ray tube,differential attenuation, absorbtion depends on density,xrays transferred on film
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Explain how using a contrast medium allows a radiographer to get an X-ray image of soft tissue.
The contrast medium has a higher density so X-rays are absorbed
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What unit is used to measure dose equivalent?
sv
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Suggest why radioisotopes with a long half-life could be considered to be more dangerous than radioisotopes with a short half-life.
They remain at a high level of activity for longer
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Suggest why radioisotopes with a short half-life could be considered to be more dangerous than radioisotopes with a long half-life.
They emit their radiation quickly so are likely to have higher levels of activity to start with.
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Suggest why alpha radiation could be considered to be more dangerous than gamma radiation.
More ionising
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Suggest why gamma radiation could be considered to be more dangerous than alpha radiation.
Harder to stop
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Why would a radiologist need to know if a female patient were pregnant before deciding to use these sorts of therapy?
The fetus can be damaged by ionising radiation.
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Other cards in this set

Card 2

Front

What is the breathing rate?

Back

12-15 breaths per minute

Card 3

Front

Tidal Volume

Back

Preview of the front of card 3

Card 4

Front

Vital Capacity (Male)

Back

Preview of the front of card 4

Card 5

Front

Vital Capacity (Female)

Back

Preview of the front of card 5
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