Mock Questions Flashcards
What can radiation do to the cells?
And what does this lead to?
Ionise them
Damage them
Kill them
Leads to:
Mutations in DNA
Cancer
What is TPhysical?
The time taken for the activity of a radioactive sample to decrease to half of its original value
What is TBiological?
The time taken for the half of the radioisotope to be removed from the body by metabolic process e.g. excretion
What is TEffective?
The time required to reduce the radioactivity of an internal organ of the whole body to exactly half of its original value due to both TBiological and TPhysical
What can affect Tphysicals half life?
Nothing, It is unaffected
What can affect TBiological half life?
Many external factors eg. Renal and hepatic function. Hydration. Anything that prevents the body from eliminating isotopes
What effects Teffectives half life?
The same factors as Tbio and Tony’s as Teff is dependant.
If a radioactive source is absorbed by the pelvic bone, what effects would it have on TPhysical, TBiological and TEffcetive?
TPhysical- Nothing
TBiological- It will stay permanently in pelvic bone until it decays naturally. bones cannot eliminate/ expell isotopes
TEffective- It is extended due to biological half life
When drawing a half life graph how is it drawn?
It is like a ski slope.. always touched the Y axis but not the X axis (always touches side axis but not bottom axis)
At what frequency does ultrasound begin?
20,000 Hz / 20KHz
How is ultrasound used to get an image of the internal organs?
Ultrasonic pulses from a transducer are transmitted into the body. these waves are reflected at the boundaries between biological structures. the reflected wave is received and converted into and electrical signal. The information is then displayed on a monitor
What is the frequency range of ultrasound when used for imaging structures near the surface?
High frequency’s (7-18MHz)
What is the frequency range of ultrasound when used for imaging deep structures?
Low frequency’s (1-6MHz)
Why do you use low frequency’s when imaging deep structure?
Deep structures are measured at low frequency’s(1-6MHz) as it gives greater penetration than high frequency’s. The disadvantage is that fine detail can’t be seen.
What is the equation used to calculate acoustic impedance?
Z= PC
What does the Z stand for in acoustic impedance equation?
Acoustic impedance (Kgm-2s-1)
What does the P stand for in acoustic impedance equation?
Density of material (Kgm-3)
What does the C stand for in acoustic impedance equation?
Speed of sound in material (ms-1)
Define and give the units for activity
The number of desintegrations per second
The unit- bacquerel (Bq)
Define and give sources of background radiation
A measure of the level of ionising radiation present in the environment.
Comes from medical sources, radon gas from rocks, cosmic rays and food
State the properties of X-rays
- X-rays are a form of ionising radiation
- They have a range of high frequencies
- They have short wavelengths
- They can penetrate less dense matter such as skin and tissue but not bone
What is the function of the filament in the X-ray tube?
It produces electrons. Electrons are accelerated towards the anode.
What is the function of the rotating tungsten target in the X-ray tube?
When the electrons strike the tungsten target, X-rays are produces. The target rotates to dissipate heat (spread out)
What is the functions of the vacuum in the X-ray tube?
This prevents the electrons interacting with the air particles. Allowing them to travel at high speeds.
What is the functions of the lead shielding in the X-ray tube?
Prevents scattering of X-rays into the surroundings- make sure the X-rays are only escaping the tube in the wanted direction
Describe what happens in the X-ray tube to produce X-rays?
Electrons produced by heating the filament
Electrons are accelerated towards the tungsten target due to high potential difference
The electrons are able to travel without any interaction with air particles, due to the vacuum in the X-ray tube
They are travelling at a high speed when they strike the rotating tungsten target, producing X-rays
The target rotates to dispute heat
State the similarities between X-rays and ct scans
Both use X-rays to create an image
Both create shadow images
State the differences between X-rays and CT scans
CT scans are more expensive
Xray is 2D, CT is 3D
CT scanner rotates, X-ray machine doesn’t
CT takes longer than xray, meaning you get a higher dose of radiation
More detail in CT image
State the methods doctors and nurses can use to minimise their exposure to radiation and why?
Lead lined apron
Stand behind lead wall to reduce chances of getting Vance and to protect soft tissues
State the properties of gamma radiation
Gamma has the highest penetrating power
Least ionising power
Why is gamma radiation a suitable source for detecting and treating cancer?
Due to penetrating power it can penetrate the body and be detected outside the body
State the properties of beta radiation
Beta is less ionising than alpha
It is also not very penetrating, it can penetrate skin but quickly looses energy
Why is beta radiation suitable for detecting and treating cancer?
It acts on the site it is placed in without contaminating other parts
What is core body temperature?
37 degrees
Plus or minus 0.5 degrees
Below what temperature is hyperthermia?
32 degrees
Above what temperature is said to be hyperthermia?
38 degrees
Below which temperature can we no longer stay alive?
25 degrees
Above what temperature can we no longer stay alive?
43 degrees
What is a radioactive tracer?
A radioactive tracer is a tracer that is inserted into the body and are used to create and image of inside of the body
What radiation is emitted from Technetium-99?
Gamma radiation
Properties of technetium-99
High penetrating power ie can penetrate through the body
Weakly ionising
Short half life (radioactive and biological)
Advantages of Technetium-99
Can be incorporated into a range biological active substances
No discomfort to the patient (other than injection)
No need got surgery- less invasive
Shows metabolic / organ activity / body functions
It becomes part of the function in the body so shows if the organ is working correctly
Risks to patient of Technetium-99
Low risk
Similar radiation dose to a X-ray
Short radioactive half life (means it decays rapidly)
Short biological half life which means the body will get rid of it quickly
However there is a risk of cell damage/ cancer
What are the precautions needed for technetium-99?
Need to avoid other people for a short time afterwards, especially Ill people, pregnant woman and children
How do u use a mercury in glass thermometer?
Place under tongue, arm, rectal
Read temp off scale
Advantages to a mercury in glass thermometer
Can be put in mouth, under arm and in the rectum Convenient Portable Cheap Rectum gives the best reading
Limitations to the mercury in glass thermometer
They take a while to react to the temp change
Have to read scale
Have to wait for liquid to travel up tube
Cant use orally after eating or drinking
Not good for children who move a lot
How do you use a digital thermometer
Sensor under tongue, arm, rectal
Get digital reading
Advantages of digital thermometer
Easy to read
Temp reading recording automatically
More robust
Very accurate (to 0.05 degrees)
Limitations of digital thermometer
Need to keep mouth closed so not good for kids
Cant use orally after eating or drinking
How do u use an electronic thermometer?
Place sensor in ear
Digital reading displayed
Advantages of electronic thermometer
Fairly accurate temp measurement
Limitations of electronic thermometer
Ear wax, swelling and infections can interfere with accuracy
Most expensive
