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