Appendix learning Flashcards
1 atomic mass unit (AMU) =
half the mass of a carbon 12 atom
Max electrons to a shell?
2nsquared n= shell number
Kinetic energy =
half mass velocity squaraed
Frequency is what relationship to T
= 1 / T
Velocity in relaton to wavelength and frequency
V = Wavelength x frequency
intensity in relation to frequency
I = plancks constant x frequency
intensity in relation to wavelength
I = plancks constant / wavelength
How do intensity and distance relate to each other
1 / d squared
in XR - how is heat calculated in J
= wave form x peak kV x mAs
Temp rise
energy applied / heat capacity
Compton probability
density / Energy
Photoelectric prob
density x atomic number cubed / energy cubed
Factor of reduction
2 to the power of HVl
LAC and HVL related how
LAC = 0.693 / HVL
MAC
= LAC / density
In CR - what is the image place made out of
Barium fluohalidate doped with Euopium ions
How thick is the image plate in CR
0.3mm
DQE =
SNR out squared / snr in squared
In DR what are the scintillators made out of
Indirect -
Caesium iodide with thallium
Matrix is made of amorpheus silicone with Hydrogen
Direct -
amorpheus Selenium
Indirect scintillator is what and gives off what colour wavelength
Green
What is the equation of Fill factor
sensitive area / total area
what is the compression on mammography
usually 100 - 150 N
max 200N
What are the different focal spot sizes?
Normal radiography is 1mm
mammography
- borad 0.3mm
- fine 0.1mm
mammo focus to film distance is always
65cm
In Fluro - what is the input made out of (both)
aluminium or titanium foil
Sodium activitated Caesium iodide
(400-500microm thick)
BLUE light
what kind of light does the fluro input make
blue
In fluro what is the photocathode?
Anitmony caesium
What is the output screen made of in fluro?
Silver activated cadmium sulphide
How thick is the output in fluro
a few micrometeres only
Gain brightness in fluro =
minification xx flux
in fluro - minification
= (input diameter/output) squared
In Fluro - image intensifier CONVERSION factor =
Luminance of the output / entrance dose rate
Normal minification factor
100
normal flux factor
100
Conversion factor in the region of
10 - 30
Tungstan atomic number and k edge
74
k edge ??
Molybdenum K edge
20
Rhodium k edge
23.3
SNR
1 / square root of photons
Geometric unsharpness / penumbra equation
Focal spot size x Focus to film distance / focus to object
in radiography - magnification equation
image size/object size = distance to image / distance to detector / distance to object
Sampling frequency in relation to Nyquist limit?
Sampling frequency = 2 x Nyquist frequency
in CT imaging detector array - how many rows and detectors in each row
8 - 64 row with 800 detectors per row
what is pitch?
the movement of the table per rotation / width of acquired slices
How is Hounsefield units worked out?
1000 x (tissue - water / water)
Equation for pixel size in CT
= FOV / image matrix size
CTDI is what
dose to the detector from a single rotation
CTDIw is what
spatial variatio nadjusted dose. 1/3 centre 2/3 periphery
CTDIvol
CTDIw /pitch (accounts for the amount radiated due to pitch)
DLP
CTDI vol x distance scanned
DLP units
mGy / cm
in CT effective dose
DLP x E (e is the value for that region receiving XR)
Aduible sound waves are where>
20 to 20 000 Hz
Speed of sound in tissue
1540m/s
US is what range of F
2 - 18 MEGA H
velocity =
square root of rigidity /desnity
velocity (relation to frequency and wavelength)
f x wavelength
Intensity (dB ratio)
10 log to the power 10 (intensity1 / intesnity 2).
Acoustic impedence =
density x speed of sound in that material
Acoustic impednance units
Kg m-2 s-1
Reflection coefficient
Z2 - Z1 all squared / Z2 plus Z1 all squared
Beam weight in US
focal length x wavelength / diamter of PZT crystal
what is the equation for Resistive Index
peak systolic frequency - end diastolic frequency / peak systolic frequency
Pulsatility index =
peak systolic - minimum frequency / time avaraged max frequency
What is the RI in a normal resistive artery
0.6
Abnormal resistive artery
0.8 - 1.0
Nyquist limit in doppler
PRF / 2
PZT is what thickness
half a wavelenth
matching layer is what thickness
quarter of a wavelength
Near field distance =
Diameter of transducer squared / 4 x wavelenth.
or radius squared / wavelenth
PRF =
frame rate x lines per frame
Distance of wave
= time x velocity x 0.5
depth of view
= 0.5 x sound velocity / PRF
What is TI
power emitted / that required to increase temp by 1 degree.
What should TI be?
less than 0.5
What is MI?
peak negative pressure / square root of ultrasound frequency.
What should by MI be less than?
0.7
Time averaged intensity
100 mW cm -2
Total sound energy in US
less than 50 J cm -2
Larmor equation =
precessional frequency = GM ratio x B0
Precessional frequency at 1 Tesla
42MHz
T1 is
time to recover 63% of B0
T2 is
time for transverse to lose 63%