Karteikarten
medical physics
Karten in diesem Stapel (78)
- 1Alpha RadiationPositively charged helium nucleus
Highly Ionising
Stopped by paper - 2Beta RadiationFast moving ejected electron
Medium ionising
Can be stopped by aluminium - 3Gamma RadiationElectromagnetic wave
Low ionising properties
Can be stopped by lead or thick concrete - 4What is half life?The time it takes for an radioactive material to decay by half
- 5What is the equation that uses speed, frequency and wavelength?
- 6What is reflection?The change in direction of a ray so the wave returns into the medium from which it has originated
- 7What is the relationship between the angle of the i and the r angle?angle of indices = angle of reflection
- 8What is the equation to work out refractive index?n = sin i / sin r
- 9How do you work out the critical angle?
- 10What is the purpose of cladding on optical fibres?It would stop light escaping. This could make the light less bright at the end if not as it would stop the light being refracted
- 11Explain why an optical fibre should be made with a material that has a high refractive indexA high refractive index means a small critical angle. A small critical angle means that more light will enter the fibre at angles greater than the critical angle. Therefore more light will be reflected.
- 12What would happen if an optical fibre was bent more sharply?More light will enter the fibre at angles less than the critical angle. Less light will then be totally internally reflected as it only occurs when the angle of incidence is greater than the critical angle. This means that the intensity drops.
- 13What does LASER stand for?Light Amplified by Stimulated Emission of Radiation
- 14What are lasers used for?Destruction of cancer tumours
Laser eye surgery
Cauterising - stopping bleeding
Nerve damage - 15What is an ultrasound?High frequency sound waves - above 20,000 Hz
- 16What are Ultrasounds used for?Destroying kidney stones
Looking at soft tissue
Looking at Urinary system
Pre-natal scanning
Looking at obstructed blood vessels - 17Advantages of using UltasoundLow cost
Non ionising
Non invasive
Would not harm baby - 18Disadvantages of UltrasoundDoesn't produce a very clear image
- 19Why is a coupling gel used in ultrasound?To prevent reflection against the skin, minimises air gap
- 20How does the computer work out how far away different types of soft tissue are?The time taken for the ultrasound to travel to the tissue and be reflected back is calculated by the computer
- 21Why is it not very useful for brain scans?The skull would absorb all of the sound rays
- 22What is the equation for the Intensity Reflection Coefficient?
- 23What types of internal radiotherapy is there?Implant - radioactive source put inside you
Tracer - the patient may swallow or be injected a tracer - 24Why is a tumour targeted from different angles?So that lots of healthy cells are not destroyed from repeated radiation in that area
- 25What is an isotope?Atoms of the same element with the same number of protons but a different number of neutrons
- 26What is Iridium-192 used for?Emits Beta and Gamma
Half life - 74 days
Used in external radiotherapy to attack tumour where cancer might be represent - 27What is Iodine-131 used for?Beta and Gamma
Half life - 8 days
Used to target thyroid cancer. Iodine has an organ affinity to the thyroid so it targets that area well. - 28What is Cobalt-60 used for?Gamma
Half life - 5 years
Most widely used isotope as an implant destroying internal tumours - 29What is Technetium-99m used for?Gamma
Half life - 6 hours
Used as a tracer to combine with other forms of radiation. Targets many organs. Used 80% of time - 30Film badgesContain film sensitive to ionising radiation
Can provide a permanent record of the radiation that a staff member has been exposed to - 31Precautions with radiationHazard signs and safety lights
Regular checking equipment
Codes of conduct - 32Reducing ExposureLead aprons
Increasing distance from source
Stand being screens or leaving room
Plaster on walls containing barium sulphate to stop radiation - 33What is the biological half life?The length of time it takes for the amount of radiation in an living organism to half
- 34What is different about the biological half life?Biological processes in the body such as the metabolism, digestion rates and breathing rates can effect the half life e.g. some radioactive material may be excreted from the body
- 35How do you work out the effective half life?
- 36Why are some radioisotopes made on site rather than bought in?They may have a short half life so they will not be active for very long before they decay and become less effective
- 37What type of radiation would an implant need to be?Alpha or beta so that it does not penetrate out of the body
Ionising - so that it will be effective in targeting the tumour
Long half life - so that it doesn't need to be replaced very often - 38What type of radiation would a tracer need to be?Gamma so that it could penetrate the skin and be detected outside the body - also so that it is not too ionising
Short half life - so that it able to be detected but is not in the body so long that it will leave the patient radioactive - 39What are X-rays?High energy, short wavelength and high frequency electromagnetic waves
- 40What is wavelength?the length of one point on a wave to the corresponding point on the next (m)
- 41What is frequency?the number of waves to pass a given point even second (Hz)
- 42What is amplitude?The height of the waves from its rest point to the peak?
- 43What is attenuation?The decrease in strength of a signal with an increasing distance
- 44What is refraction?Bending of a wave as it passes from one medium to another of a different density
- 45What is systolic pressure?Pressure when the ventricles contract
- 46What is diastolic pressure?Pressure when the ventricles have relaxed
- 47What is an EEG?Electroencefephalgram - measures the activity of the brain
- 48What is an ECG?Electrocardiogram - measures the activity of the heart
- 49What is background radiation?Radiation that comes from naturally occurring radioactive material that is always surrounding us
- 50What is a stochastic effect?Cancer effects - this is dependant on the dose. Happens randomly but does not vary in effect
- 51What is a non stochastic effect?Hair loss/burns. This varies in severity and is dependant on the dose above the threshold
- 52What is a CAT scan?Computer Axial Tomography.
Uses xrays to rotate around the body to produce cross sectional images/3D images - 53MRIMagnetic Resenonse Imaging
Uses magnetic properties to detect hydrogen atoms in the cells to look at the soft tissue - 54Explain how blood pressure is taken.A cuff is placed around the arm level with the heart. The cuff is inflated slowly whilst the stethoscope is placed on the inner elbow. The cuff is deflated until a sharp tapping sound is heard. This s the systolic pressure. It is then deflated again until there is silence. This is the diastolic pressure. It is presented as systolic/diastolic (mmHg)
- 55What is the blood pressure of a baby at birth?80/50
- 56What is the pressure of an 18 year old boy?120/80
- 57What is the pressure of an elderly man?160/85
- 58What is the pressure of a healthy young male?125/80
- 59What is the blood pressure of a pregnant women?90/80
- 60Was is the range for normal body temperature?36.5 - 37.2
- 61What temperature is hypothermia?below 32
- 62What temperature is hyperthermia?above 38
- 63What temperatures would lead to someones death?below 25 or above 43
- 64What is vasodilation?When the capillaries widen and there is an increased blood flow to the skin - this happens when someone is too hot
- 65What is vasoconstriction?The vessels narrow and blood flows to the core - used to reduce heat loss when someone is too cold
- 66What is sinus tachycardia?When the heart beats faster than 100 bpm
This is a normal response to exercise, stress or anger
It indicates blood flow has been restricted - 67What is sinus bradycardia?When the heart beat is too slow
This causes extreme tiredness, dizziness, fainting and shortness of breathe - 68What is sinus arrhythmia?This is heart palpitations or irregular heart beat
This can lead to death - 69What is ventricular fribualation?This is where there is little or no blood being pumped around the body. The patient may go into cardiac arrest and die
- 70What are EEGs used for?Research sleep
Looking for dementia
Brain tumours
Coma
Monitoring a patient during surgery - 71What is thermography?Uses heat of body
Non invasive
Can be used to detect tumours as they would show up more red on the thermograph - 72What are advantages of using thermography?No harmful radiation
Locates problems for further tests
Non invasive - 73What are disadvantages of using thermography?Expensive and easily damaged
Requires experienced professionals
Surfaces only
Image quality lacks sharpness - 74What is an encased glass tube used for in xrays?To keep a vacumm
- 75What do xrays do when they hit the body?They travel through soft tissue and are attenuated by bone/dense material
- 76What type of rays do MRIs use?Magnetic waves
Radio waves - 77What does the MRI scanner have to do with the hydrogen nuclei?Protons in the hydrogen atom are magnetic
MRI sends small radio waves to shock the protons out of alinement so that they can be seen - 78What are disadvantages of using MRI scanners?Expensive
Specialist equipment
Claustrophobic and seen to disturbing by some
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- A Level Applied Science - Medical Physics Karteikarten am medical physics, erstellt von Kathryn Tweddle am 30/03/2015.
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- Kathryn Tweddle
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