Cheat sheet Flashcards
I-123 Normal A? Mode of decay principle energu physical half life
53
Electron capture
159keV
13.2h
Str-89 Normal A? Mode of decay principle energu physical half life
38
Beta - Yttrium 89
None
50d
O-15 Z? Mode of decay principle energu physical half life
8
B+ (neutron poor) - N15
173keV
2 minutes
F-18 Z? Mode of decay principle energu physical half life
9
B+ (neutron poor) - O18
635keV
110min
Mo-99 Z? Mode of decay Principle energy Physical half life
42
B- (neutron excess) - Tc-99m
740keV
67h
I-131 Z? Mode of decay Principle nergy physical half life
53
B- (neutron excess) –> Xe-131
364keV
8d
Tc99 Z? Mode of decay Principle energy Physical half life
43
Isomeric transition
140keV
6 hours
What are half lives: Tc99 F18 Io131 Co57
Tc - 6.0h
F18 - 110min
I131 - 8.0d
Co57 - 271.8d
Wavelength of violet light
380-450nm
Wavelength of blue light
450-500
Wavelength of green light
500-570
Yellow light wavelength
570-590
Orange light wavelength
590-620
Red light wavelength
620-750
UV light wavelength
400-10nm
X-ray wavelength
0.01-10nm
Gamma ray wavelength
10^-12
US frequency
2-20MHz
Gamma ray frequency
10^19Hz
Ca
Z?
K-edge?
20
4.5keV
Iodine
Z?
K-edge?
53
34.5keV
Barium
Z?
K-edge?
56
40.4keV
Cesium
Z?
K-edge?
55
38.9keV
Tungsten
Z?
K-edge?
74
69.5keV
Lead.
Z?
K-edge?
82
93.1keV
Bismuth
Z?
K-edge?
83
95.7keV
Yttrium
Z?
K-edge?
39
17keV
Gadolinium
Z?
K-edge?
64
50.2keV
Molybdenum
Z?
K-edge?
42
21keV
Law of transformers in regards to # of turns?
Np/Ns = Vp/Vs
Law of transformers in regards to voltage?
VpIp = VsIs
Conversion efficiency of CaWO4 vs rare earth screens?
CaWO4 - 5%
Rare earth = 20%
Absorption efficiency of film, CaWO4 or rare earth screens?
Film - 1%
CaWO4 = 20%
Rare earth = 40-60%
Optical density equation
OD = log (1/T) OD = log (Io/I) = without a film/with a film
Calculation of transmittance?
T = I/Io
With a film/without a film
Deterministic effects?
- Practical threshold – below this dose – no effects occur
- Severity increases with dose – degree of change increase with dose
- Skin erythema, sterilization, cataracts
Stochastic effects?
- Severity is independent of dose
- No threshold
- Probability increases with dose
Examples: hereditary effects, cancer
Transient equilibrium?
Parent’s T1/2 is 10x that of daughter
Equilibrium reached in 3.8 daughter T 1/2
Secular equilibrium
Parent’s T1/2 is 100x that of daughter
Equilibrium reached in 5-6 daughter T1/2
How do you calculate magnification?
L image / L object
A+B/B
A = source to object
B = object to film
How do you calculate true magnification?
M = m + (m-1)/(f/d)
How do you calculate the penumbra?
Lg = Lf (b/a) B = object to film distance A = source to object
How do you calculate the penumbra?
Lg = Lf (b/a) B = object to film distance A = source to object
Typical pixel format and bits/pixel for:
Planar gamma camera
Matrix: 64 or 128
Bits/pixel: 8 or 16
Typical pixel format and bits/pixel for:
Digital radiography
Matrix: >2000
Bits/pixel: 12-16
Typical pixel format and bits/pixel for:
fluoroscoxpy
512 or 1024
12 bits/pixel
Typical pixel format and bits/pixel for:
CT
512
12 bits/pixel
Typical pixel format and bits/pixel for:
MRI
64 to 1024
12 bits/pixel
Typical pixel format and bits/pixel for:
US
512
8 bits/pixel
Limiting spatial resolution:
Screen film
0.08mm
Limiting spatial resolution:
Digital radiography
0.17mm
Limiting spatial resolution:
Fluoro
0.125mm
Limiting spatial resolution:
CT
0.3mm
Limiting spatial resolution:
Nuc med
2.5mm
Limiting spatial resolution:
SPECT
7mm
Limiting spatial resolution:
MRI
1mm
Limiting spatial resolution:
US
0.3mm
Thickness of PZT?
High frequency vs low frequency?
1/2 wavelength
Low frequency = thicker crystals
High frequency = thinner crystals
What is the q-factor?
Q = center frequency / bandwidth
Describes bandwidth of sound emanating from a transducer and length of time it persists
Describe a low Q factor
Useful for pulse imaging (tissue)
Better receivers
Heavy damping - resulting in short SPL/short ring-down, and an impure sound (broad bandwidth)
Improved spatial resolution
Describe a high Q factor
Useful for pulsed Doppler imaging Better transmitters Light damping - long ring-down that results in a long SPL Pure sound (narrow bandwidth) Decreased spatial resolution
How thick is the matching layer?
1/4 the wavelength
What is the pulse repetition frequency?
# of pulses/s in kHz - 2-4kHz Pulses = SPL (# of cycles x wavelength) - usually 3 total wavelengths
How is PRF related to frame rate?
PRF = frame rate x # of echo lines x FR
What is the maximal range of a pulse?
77,000/PRF
What is the pulse repetition period?
Time from the beginning of one pulse to the next
Inverse of the PRF
PRP = 1/PRF
Increase the PRF - will decrease the PRP
When do you need to use a lower PRF?
Low frequency transducers - have increased depth - need more time to listen for returning echoes (range ambiguity artifact may occur)
What is the pulse duration?
Time if takes for 1 pulse to occur
Ratio of # of cycles in the pulse to transducer frequency
# of cycles/pulse divided by transducer frequency
What happens to pulse duration if the frequency is increased?
Pulse duration will decrease
Period will also decrease
What is the duty factor?
Fraction of ‘on’ time
Pulse duration / PRP
What does a higher PRF do to the duty factor?
Duty factor = pulse duration / PRP
Higher PRF = smaller PRP = higher duty factor
Using a higher frequency transducer = more on-time… has less penetration and does not need to wait for returning echoes
What is the spatial pulse length?
What does determine?
SPL = wavelength x # of cycles
Typically - 2-3 cycles per pulse
1/2 SPL = axial resolution
What is a typical duty factor for real time imaging?
0.2-0.4% the rest is in listening mode
