NUKS Flashcards
1
Q
Beta minus
too many?
what’s emitted?
What kind of transition
A
Too many neutrons
N > P
electron (beta particle) emitted from nucleus
Neutrino also emitted to balance energy
ISOBARIC - neutron and proton have same mass
ATOMIC NUMBER GOES UP
2
Q
Beta emitter shielding?
A
PLASTIC
low Z
High Z would produce Brems
3
Q
\
\
\
A
Beta Minus
Energy down, Z up
4
Q
I
I
/
/
/
A
Energy lost and Z goes down
Proton to neutron
Beta positive decay
requires 1.02 MeV
Positron and a neutrino
511 keV x2 when positron hits electron
ISOBARIC
5
Q
/
/
/
/
A
No steep initial drop
loss of proton and energy
ELECTRON CAPTURE
ISOBARIC
6
Q
isobaric transitions
A
Beta emission
positron emission
electron capture
7
Q
“Isometric transitions”
when do they occur?
A
after an isobaric (A the same) transition
leftover energy released
8
Q
Gamma emission
what type of transition
A
isomeric transition
nucleus emits extra energy
I
I
V
9
Q
Between Isobaric transition and subsequent isomeric (GAMMA EMITTING) transitions
A
These usually happen bam bam, but some hang out for a minute before gamma emission, these are METASTABLE
10
Q
Tc 99m example of isobaric metastable isomeric
A
Mo99 —> Tc99m (ISOBARIC Beta MINUS, electron emitted)
Tc99m ——> Tc99 (ISOMERIC, gamma photon (140keV))
Tc99m hangs out as metastable for a couple hours
11
Q
Enemy of gamma photon emission
A
Internal conversion
instead of gamma emission
energy given to an electron —–> characteristic Xray or Auger
12
Q
Alpha decay
use?
A
helium nuclei
2 protons, 2 neutrons
Slow and fat
rare treatmentn situations
bone pain cancer mets via rAdium 223 (Alpha2protons2 neutrons)
13
Q
Production
Bombardment
A
Striking targets with
Neutrons - in a reactor
Charged particles (alpha, protons, deuterons) - in a cyclotron
14
Q
Bombardment
downside to using a reactor
(bombarding with neutrons)
A
Leftover parent to clean up
NOT “carrier free”
Cyclotron produces via transmutation, no parents to clean up, “carrier free”
15
Q
Production
Fission
A
Neutrons fired into large elements
split into pieces, random crap made
16
Q
effective half life formula
A
1/effective = 1/physical + 1/biologic
17
Q
What does ‘activity’ measure
units
Specific activity
A
disintegrations per second
Curie = Ci = 3.7x10^10 disintegrations per second
SI unit = becquerel Bq = one disintegration per second
Specific activity = activity per unit mass (Bq/g)
(longer half life = lower specific activity)
18
Q
Gamma camera general set up
A
Photons
Collimator
Crystal
PMT’s
computer
gamma photons –> light pulse –>voltage –> picture
19
Q
MC collimator “work horse”
A
parallel hole
20
Q
Parallel hole energies and examples
low
medium
high
A
LOW 1 - 200 keV (Tc99, I123, Xe133, TI201)
MEDIUM 200-400 keV (Ga67, In111) (medium needs to GaIn)
High > 400 keV (I131)
21
Q
Sensitivity and Resolution
when are high sensitivity collimators good
A
Inversely related
High sensitivity collimator allows twice as many counts to be imaged with shitty resolution
High sensitivity good for dynamic imaging (flow phase)
22
Q
Distance effect on sensitivity and resolution
A
NO EFFECT on sensitivity (net counts the same, bigger FoV)
Resolution WORSENS with distance
23
Q
Pinhole collimator
what does?
what for?
?mag
A
magnifies and inverts
thyroids and small parts
pinhole to detector = f
patient to pinhole = b
F>B = mag
24
Q
Pinhole cons
A
distorts large objects
Shitty sensitivity
25
Converging collimator
what look like?
what does?
fan out towards detector
mags without inverting
26
Diverging collimator
what is
what does
Opposite of converging
fan towards patient
MINIMIZES
Able to image a large body part on a small crystal
27
After collimator, photons hit?
Scintillation crystal
28
scintillation crystal made of?
what does
NaI doped with Thallium
when hit with a gamma photon, produces a pulse of light
29
Thick vs thin scintillator crystal?
**Thick = super sensitive**, fewer pass through. PMT's are further away = **WORSE resolution**
**Thin = less sensitive, better resoltution**
30
After scintillator crystal?
PMT's
31
PMT's
do what?
more means what
what do they record
detect light and convert to an electric signal
More = more light picked up, greater resolution
PMT's record X,Y location- read by computer and..
Z location/intensity goes to pulse height analyzer
32
Pulse height analyzer
job?
distinguishing, discarding background crap
Compton scatter from patient is very close in energy to what you want, but can really fuck it up
33
Downscatter
high energy photons spill into the window of a low energy emitter, mostly via Compton scatter
Ex
V/Q with Tc (140) and Xe (81)
Tc scatter will range down from 135 -90
So if you give Tc first, subsequent Xe image will be covered in Tc scatter
**USE LOWER ENERGY FIRST**
34
SPECT and matrix
SPECT overall improves spatial resolution
image longer, looks better
Bigger matrix better but takes longer (motion problem)
and fewer counts per pixel = worse image contrast
35
Startifact
"septal penetration"
using medium energy collimator instead of high
36
Gamma camera QC
Uniformity
% allowed
what is test?
extrinsic vs intrinsic
2-5% non-uniformity
1% for SPECT
Test = Flood
Extrinsic = with collimator
Intrinsic = without
test with Co57 or NaPertech
**EXTRINSIC DAILY, INTRINSIC WEEKLY**
37
Gamma camera QC
Window setting
when?
how?
**DAILY**
Use a symmetric window set at peak energy used for desired test
source = syringe or vial
38
Gamma camera QC
Linearity and Spatial resolution
When?
How?
**WEEKLY**
lead line phantoms placed between collimator and a Co57 sheet. Want straight not wavy lines
linearity = lines
spatial res = they're separate
39
Gamma camera QC
Center of rotation
**WEEKLY**
SPECT
monitor for alignment offset at COR
Tc99 point sources along axis of rotation, axis should be straight with minimal deviation
40
Instruments
NaI well counter
what is
con
basically a small gamma camera with a **single PMT**
EASILY OVERWHELMED
used for in vitro blood or urine samples, "wipe test" samples
41
Instruments
Thyroid probe
what is
**Modified NaI counter**
shielding with a small opening pointed at patient, at a precise distance, compared to a calibrated capsule of same radionuclide
42
Instruments
Geiger-Muller
dead time?
gas ionization chamber
sensitive to large dose, must wait for ionization to dissipate before it can respond again.
max dose = 100mR/h
43
Instruments
Ion chamber
no dead time problem
0.1 - 100R/h (big unit)
higher doses
less sensitive than GM counter
excellent for accurate estimates (or exposure)
44
Personal dosimeters
Pocket ionization detector
uses a mini-chamber
real time estimated dose
must be charged and zero'd
NOT used anymore
45
Solid state dosimeter
accumulated dose or rate can be read real time with LCD display
solid state think LCD
46
Personal dosimeters
Film badge
thin metallic radiosensitive film
degree of darkening (relative optic density) corresponds to dose
sensitive to damage by temp, humidity
47
Personal dosimeters
optically stimulated
Replaced film badge
chips/strips placed under a filter
48
Personal dosimeters
ring badge
dominant index, label in
Thermo-luminescent
49
Dose calibrator QA
Consistency
**DAILY**
**should be within 5%**
50
Dose calibrator QA
accurate readout over whole range of potentially encountered activities
check either with a large (200mCi) amount of Tc and decaying it down
or easier
use a kit with sheets of varied thickness of lead
**QUARTERLY**
51
Camera linearity **and spatial res**
**vs**
Dose calibrator linearity
Camera linearity **and spatial res - WEEKLY**
**vs**
Dose calibrator linearity - **QUARTERLY**
52
Calibrator QA
**A**ccuracy
Standard measurements measured and compared to what they shoud be
INSTALLATION AND **A**NNUALLY
53
Dose calibrator QA
Geometry
Correction for different positioning and size (different volumes of samples with same activity)
## Footnote
**INSTALLATION AND ANY TIME YOU MOVE DEVICE**
54
calibrator QA mnemonic
**GALC**ulations (decreasing frequency)
## Footnote
**Geometry - install/move**
**Accuracy- annual**
**Linearity- quarterly**
**Consistency - DAILY**
55
Major spills
Tc99
\> 100 mCi
56
Major spills
Tl - 201
\>100 mCi
57
Major spills
In-111
\> 10 mCi
58
Major spills
Ga-67
\> 10mCi
59
Major spills
I 131
\> 1mCi
60
Major vs minor spill who ya gonna call
minor - clean it yourself
major call RSO
61
Minor spill to do list
1) address a sick patient first
2) Confine/limit - secure area
3) Clean up (gloves)
4) survey cleanup items
5) survey cleanup people
62
General public regs
annual dose limit
100 mrem
63
"unrestricted area" max dose
2 mrem per hour
64
Restricted area =
any area getting over 2mrem per hour
65
"radiation area"
.005 rem (.05 mSv) in 1 hour at 30 cm
66
"high radiation area"
0.1 rem (1mSv) in 1 hour at 30 cm
67
"Very High radiation area"
500 rads (5Gy) in 1 hour at 1 meter
68
Occupational dose limits
Total body dose per year
5 rem (50mSv)
69
Lens
2 rem per year (20 mSv)
70
Total equivalent organ dose
50 rem (500 mSV)
71
Extremity dose per year
50 rem (500mSv)
72
fetus dose for 9 months
0.5 rem (5mSv)
73
Unit fuckery
rad rem
rad Gy
mSv mrem rem
1 rad = 1 rem
1 rad = 0.01 Gy
1mSv = 100 mrem = 0.1 rem
74
NRC
part 19
Notices, instructions, reports to workers
75
NRC
part 20
Standards for protection
76
NRC
part 35
Medical use of by-product material
77
Medical event vs recordable event
medical event = wrong drug, patient, or dose
or dose to unintended body part other than intended treatment site 50% or more over dose expected
AND
Have to harm the patient
-whole body dose \> 5 rem or single organ dose \> 50 rem
78
Recordable
Whole body \<5rem
Single organ \< 50rem
79
For medical events what u do
call the doctor, patient, NRC
Recordable... record it (document) and keep for 5 years
80
Receiving and storage
survey package **within 3 hours**
GM at surface and 1 meter away
surface wipes
81
Package labels
White 1
NO special handling
\<0.5 mrem/hr at surface
0 mrem/hr at 1 meter
82
Labels
Yellow 2
Special handling required
surface \<50 mrem/hr
1 meter \<1 mrem/hr
83
Labels
Yellow 3
Special handling required
surface \<200mrem/hr
1 meter \<10mrem/hr
84
Transport index
measured max dose at 1 meter
Radioactive 1, white 1, no TI, too low
Radioactive II, yellow 2, \< 1.0 mR per hour
Radioactive III, yellow 3, TI \> 1.0mR per hour
85
how Tc is made
Mo and Tc
Mo - 67 hours
Tc - 6 hours
Mo-99 lined aluminum canister, as it decays can be washed off with saline
Tc comes out stuck to Na (Na99Tc04)
+7 valence state, must be reduced to be used
Reduced with Stannous ions
86
How Tc is made
moly breakthrough
If Mo comes out in the wash
"break through"
assayed behind a lead shield
Mo (740 keV) will penetrate
87
Mo breakthrough, what kind of purity?
allowed?
**RADIONUCLIDE PURITY**
0.15 microCi of Mo per 1 mCi of Tc
15 micro per milli Mo to Tc
ratio must be known at time of ADMINISTRATION
88
Chemical purity
**Al oxide** can wash off, **clump with Tc** and show up **in liver** or cause **sulfur colloid aggregation and show up in the lungs**
Test?
pH paper
\<10 micrograms Al per 1ml
Testing for chemical purity NOT REQUIRED in NRC states
89
Radiochemical purity
Tc comes out of generator as Na99TcO4, needs to be reduced with SnCl2
Assessed with thin layer chromotography
limits for free Tc
95% for Na99TcO4
92% for Tc sulfur colloid (MAA)
91% for the rest
90
Equilibria
Equilibrium
[] of parent and daughter are equal
91
Transient equilibrium
half life of daughter is shorter than parent (not by a ton)
moly and Tc after 4 half lives
92
Secular equilibrium
half life of daughter is way way way shorter than parent
93
Critical Organ
Indium
Liver
94
Critical Organ
I 131 MIBG
Liver
95
Critical Organ
Sulfur Colloid (IV)
Liver
96
Critical Organ
Octreotide
Spleen
97
Critical Organ
Damaged RBC
Spleen
98
Critical Organ
pertechnetate
Stomach
99
Critical Organ
Gallium
Distal colon
100
Critical Organ
Mag3
bladder
101
Critical Organ
DTPA
bladder
102
Critical Organ
I 123 MIBG
bladder
103
Critical Organ
MDP
bladder
104
Critical Organ
Sestamibi
Proximal colon
105
Critical Organ
sulfur colloid (oral)
proximal colon
106
Critical Organ
DMSA
Renal CORTEX
107
Critical Organ
Thallium
Renal cortex
108
Critical Organ
HIDA
GB wall
109
SPECT vs PET
?depth dependent
SPECT is depth dependent
PET IS NOT
110
Main advantage to SPECT?
Improved contrast from overlapping structures
111
SPECT center of rotation artifact
TUNING FORK appearance
misregistration
112
Crystals in PET
| (vs SPECT)
PET tends to use thicker crystals (BGO, LSO, LYSO)
(SPECT uses planar crystals, NaI)
113
PET
limiting factor for spatial res?
BIG thick crystals (bigger means fewer)
114
Positron range
actually detecting location of anihilation event
positron can travel 1-2mm prior to event
115
PET
angulation
sometimes 180 is a generalization
180.5, will be off a little bit in localization
116
PET coincidence events detected
3 types
True
Scatter coincidence - one of pair is scatterd, hits within time window but not in right location)
Random coincidence - Different anihilation events, land within same coincident window creating false calculation
117
PET
2d vs 3d
**2D has lead septa** - also decreasing sensitivity for unscattered photons
**3D no septa** - MORE sensitive, allows for decreased tracer dose.
**3D usually done with small parts - CNS and PEDS**
118
PET
3d disadvantages
Dead time
more random events - no septa
More scatter - no septa
119
SUV's
equation
Tissue radioactivity concentration at time point 1 x patient weight
--------------------------------------------------------------------
Injected dose activity
120
SUV's and fat people
LBM vs weight
SUV's are overestimated in fat people
More accurate to use LBM
121
PET and glucose
PET and small stuff
High glucose lowers SUV
Smaller than 1cm, lower SUV
122
Truncation PET FOV vs CT FOV
CT FOV is SMALLER
Lesion in the outlying blubber gets cut off by CT, seen by PET
Lesion appears ARTIFICIALLY HOT at the margin, ARTIFICIALLY COLD outside the CT FOV
123
PET prep
?fasting
Causes of muscle uptake?
Brown fat drugs
4 hours minimum fasting
exercise, eating or insulin
Propranolol and valium
124
PET QA
Blank scan
DAILY
equivalent of uniformity
keeps attenuation correction data accurate
'start each day with a blank slate'
125
PET QA
Normalization scan
MONTHLY
disrepancies in the detector elements
scan a calibrated position source
NM Normal month
**HORIZONTAL LINEAR STREAKS if normalization is off**
126
PET QA
bucket setup
dark block rotating on a sinogram
power surge or sudden power loss
127
**TRACER TRIVIA- Tc99**
**Analog**
**Energy**
**Physical half life**
**140 keV - LOW**
**6 hours**
128
**TRACER TRIVIA- I 123**
**Analog**
**Energy**
**Physical half life**
**Iodine**
**159 keV - LOW**
**13 hours**
129
**TRACER TRIVIA- Xenon 133**
**Analog**
**Energy**
**Physical half life**
**81 keV - LOW**
**PHYSICAL 125 hours**
**BIOLOGIC 30 seconds**
130
**TRACER TRIVIA- Thallium 201**
**Analog**
**Energy**
**Physical half life**
**Potassium**
**LOW 135, 167 keV**
**_USE daughter Hg xrays_**
131
**TRACER TRIVIA- Indium 111**
**Analog**
**Energy**
**Physical half life**
**MEDIUM 173 keV, 247 keV**
**67 hours**
132
**TRACER TRIVIA- Ga 67**
**Analog**
**Energy**
**Physical half life**
**IRON**
**93, 184, 300, 393 (100, 200, 300, 400)**
**78 hours**
133
**TRACER TRIVIA- I 131**
**Analog**
**Energy**
**Physical half life**
**Iodine**
**365 keV HIGH**
**8 days**
134
**TRACER TRIVIA- F 18**
**Analog**
**Energy**
**Physical half life**
**GLUCOSE**
**511 keV HIGH**
**110 minutes**
135
**Treatment radionuclides 1/2 life**
**Strontium 89**
**50.5 days (14 days in bone)**
136
**Treatment radionuclides 1/2 life**
**Samarium 153**
46 hours
137
**Treatment radionuclides 1/2 life**
**Y 90**
64 hours
138
**Treatment radionuclides 1/2 life**
**Radium 223**
**11.4 days**
139
