Nuclear Medicine Flashcards
(109 cards)
1
Q
What is this describing?
Medical specialty that focuses on the use of radiopharmaceuticals.
A
Nuclear medicine
2
Q
T/F
Nuclear medicine is based off of physiologic function of organs or tissues
A
True
3
Q
What modality is this describing?
- Limited anatomic Information
- Less spatial resolution
- High sensitivity and specificity for molecular processes (if the area of the brain is responding)
A
PET scans
4
Q
What is a hot spot?
A
An area of high activity
5
Q
What is a cold spot? What could it be an indicator of?
A
-An area of low activity
-Could be an indicator of infarction
6
Q
What is a radiopharmaceutical reffered to in medical imaging?
A
Referred to as radiotracer/tracer
7
Q
How are radiotracers introduced to the body?
A
- Injection (intravenous, intradermal, intrathecal)
- Inhalation
8
Q
How are radiotracers chosen for exams?
A
Selected based on their ability to localize in specific organs/tissues
9
Q
What type of radiation do radiotracers emit?
A
Gamma radiation
10
Q
What is the purpose of radiotracer radiation emission?
A
Emissions allow for the detection of the tracer’s presence
11
Q
What type of detectors detect gamma emission?
A
Scinitlation detectors
12
Q
T/F
Naturally occurring radionuclides have very short half-lives
A
False; Naturally occurring radionuclides have very long half-lives
13
Q
Where are radionuclides produced?
A
- Particle accelerators (cyclotrons)
- Nuclear generators
14
Q
What makes up a Radiopharmaceutical?
A
Radionuclide + Pharmaceutical
15
Q
What is this reffering to?
A biologically active compound chosen because of its preferential localization or participation in the physiologic function of a given organ
A
A Pharmaceutical
16
Q
What is a radionuclide?
A
It is a radioactive material used to tag the pharmaceutical
17
Q
How long can a PET scan be?
A
Up to 1 hour
18
Q
When do you begin a PET scan?
A
Until radiopharmacutical is absorbed by the anatomy
19
Q
T/F
After the radiopharmaceutical is administered, the target organ is localized by means of the physiologic pharmaceutical distribution, and the radiation emitted is detected by cameras
A
True
20
Q
What are the 4 most common radionuclides?
A
-11C
-13N
-15O
-18F
21
Q
What radionuclide replaces hydrogen in many molecules?
A
18F
22
Q
Radionuclides do not disrupt any bodily biochemical processes and mechanisms.
A
True
23
Q
What does 18F emit?
A
Positrons which makes radioactive glucose
24
Q
When do radioisotopes and radiotracers need to be produced?
A
Radioisotopes and radiotracers need to be produced on the same day as the scan
25
# TF
Radioisotopes and radiotracers need to have a short half life.
True
26
What are the 2 steps to isotope production?
1. Radiochemist produces radioisotope using a cyclotron
2. Attach the radioisotope to a biomolecule
27
# T/F
Radiopharmacuticals are; easy to produce, readily available, have a low cost, are easily administered and concentrate in specific organs or tissues.
True
28
# T/F
Radiopharmaceuticals need to be sterile in order to be injected.
True
29
What is Half-life?
The time it takes for half of the atoms to decay
30
What is C-decay?
Starts off and then quickly decays
31
# T/F
A less stable radionuclide will have a short half life.
True
32
Is half life exponential or linear?
Exponential
33
What is a positron?
An antielectron
34
What is emission?
Radioactivity emitted from an unstable nucleus inside the subject
35
Describe the process of isotope production:
Acellerators fire particles at really high speeds in the presence of oxygen to create radioactive elements
36
What is the issue (n:p ratio) with radionuclides used in PET imaging?
Too many p
37
What type of decay does the radionuclide undergo?
Beta positive decay
38
What particles are created from the decayed radionuclide?
1. Positron
2. Nutrino
39
How is annihilation radiation created?
Created by an interaction of a positron witha nearby electron
40
How many particles are created from annihilation radiation? What is their energy?
-2 particles created
-511kEV photons
41
What type of radiation does the detector in PET scans register?
Annihilation radiation
42
At what degree is annihilation radiation produced at?
180 degrees to eachother
43
# What is this describing?
The conversion of matter into energy, especially the mutual conversion of a particle and an antiparticle into electromagnetic radiation
Annihilation
44
What is the speed of annihilation radiation?
The speed of light
45
What is coinsidence detection?
Two 511kEV photons hitting the detector at almost the same time at different angles
46
# T/F
Wavelength and f are variable and inversely proportional to eachother
True
47
What are the 2 Radiopharmaceutical Physiological Processes?
1. Receptor/ligand based process
2. Enzyme/substrate based process
48
What is the receptor/ligand based process for radiopharmaceuticals?
Radiopharmaceutical goes into the bloodstream, to the tissue, attaches to a receptor and decays
49
What is the enzyme/substrate based process for radiopharmaceuticals?
Radiopharmaceutical enters the cell, is partially metabolized, and releases radiation by decay
50
# T/F
The diagnostic information obtained from imaging the distribution of radiopharmaceuticals is anatomical.
False; The diagnostic information obtained from imaging the distribution of radiopharmaceuticals is functional
51
What is FDG primarily used for?
Identifiying sites of malignancy
52
What forms FDG?
Hydroxyl group (OH) has been replaced with radioactive fluorine (18F)
53
What compound Measures glucose metabolism?
FDG
54
What percentage of PET scans is FDG contrast used?
95% of PET scans
55
What contrast is the best for brain mapping?
FDG
56
What is PET sensitivity?
The fraction of the annihilation pairs that are detected
57
What is PET sensitivity affected by?
Number and type of detector
58
What is the LoR?
The detectors detect radiation and find a line between those two points.
59
When does a true coincidence occur?
When both annihibaltion photons escape without interaction with tissue and strike the detectors.
60
# TF
Scatter and absorption both occur in equal amounts with true coincidence events
False; No scatter occurs in true coincidence events
61
What are random coinicidences?
When two annihilation photons from separate emissions strike the detectors at the same time and then get falsey attributed to a different original event
62
What are scatter coincidences?
One or both annihilation photons get scattered in tissue, looses E and then travels at another angle
63
What is the basic component of a PET scanner called?
The block
64
What is a block is composed of?
A block is composed of a scintillation crystal coupled with 4 PMTs
65
How are the blocks organized? What do they form?
The blocks are then organized in a row to form detector modules
(The modules are aligned side by side to form a ring)
66
How many detectors are there per ring?
800-1000 detectors per ring.
67
What does a PMT do?
Photosensor (PMT) used to convert light to an electrical signal
68
# T/F
The scintillation crystal has a high mass density & atomic number.
True
69
Label 1-5
1. PMT
2. Crystal
3. Anode
4. Dynode
5. Photocathode
70
Where are the collimators located in PET scans, and what is thier function?
-Located at the face of the detector, where photons first enter
-Filters gamma rays not perpendicular to the detector and removes scatter
71
# T/F
Collimators are made of material with high atomic number, like lead.
True
72
How is collimator sensitivity determined?
Collimator sensitivity is determined by the fraction of photons transmitted through the collimator and strike the detector
73
What does the PET detector module measure?
1. The time it takes the gamma rays to hit the detector
2. Position (where gamma photon hits detector)
3. Energy
74
What converts the gamma photon into light?
The scinitllation detector
75
What converts the light into an electronic signal
A photosensor
76
What are the 2 forms of image reconstruction in PET scan imaging?
1. Filtered Back Projection
2. Iterative Reconstruction
77
What are the majority of PET scans done for?
Majority of PET scans are done to diagnose, stage, or restage cancer
78
What are the 3 different ways in which signal detection can be expressed?
1. Expressed as shades of grey
2. Expressed as colour tables
3. Expressed as linear colour tables
79
What does SPECT stand for?
Single Photon Emission Computed Tomography
80
What is the difference between PET and SPECT imaging?
Single photon (gamma ray) is emitted as opposed to positrons.
81
What is the parent nuclide of 99mTc (Technetium)
99Mo
82
What decay occurs to create 99mTc?
Beta negative decay
83
What are the two main pharmacuticals in which 99mTc is tagged to?
1. Tagged to macroaggregated albumin (99mTc MAA)
2. Tagged to Methyl-diphosphate (99mTc MDP)
84
Where is 99mTc MAA deposited?
Trapped in small pulmonary capillaries in the lungs
85
What is 99mTc MDP used for?
Bone scans for fractures
86
# What modality is this?
Mostly used for cardiac perfusion, brain, liver, tumor and bone studies
SPECT
87
How to the detectors move in relation to the patient?
Detectors rotate 360 degrees around patient
88
What are the 2 other names for gamma cameras?
1. Scinitillation camera
2. Anger camera
89
What device is used to image gamma radiation emitting radioisotopes? What is this technique known as?
-Gamma cameras
-Technique: scintigraphy
90
How many heads does a SPECT camera have?
2-3 (mostly 2)
91
What is being shown here?
Anger cameras
92
What is a static/spot view in SPECT imaging?
A snapshot of radiopharmaceutical distribution in the body obtained in various orientations around a structure to show multiple spots of the anatomy
93
# T/F
For static views, Images must be acquired for a pre-set amount of time or a minimum number of counts or radioactive emissions
True
94
# T/F
In static imaging, the patient and detector to move with respect to each other and produce whole body images
False; **in whole body imaging**, sweep images allow the patient and detector to move with respect to each other and produce whole body images
95
What is this showing?
Spot Imaging with SPECT
96
What is being shown here?
Whole body scan
97
# What is this describing?
Refers to the acquisition of multiple sequential images at defined intervals or over time in which sequential images are collected and aligned together to show function over time
Dynamic imaging
98
What is being shown here?
Dynamic imaging
99
What are the two types of hybrid imaging systems in nuclear medicine?
1. SPECT/CT
2. PET/CT
100
What are the benefits of hybrid imaging systems?
1. Allows fusion of anatomical and functional images
2. Provides increased diagnostic accuracy
3. Position of suspected tumors can be recognized more easily
4. Metabolic and anatomic evaluation after therapy can now be accomplished in one imaging session
101
What is one con of hybrid imaging systems?
Misregistration possible due to difference in patient positioning
102
What is being shown here?
Hybrid imaging sytem
103
What is being shown here?
PET/CT Fusion Images
104
# What is this reffering to?
Antibodies specifically designed to localize on the surface of different types of cancer cells can now be tagged with a radioisotope and then imaged
Radioimmunotherapy
105
What radiation safety measures are put into place for nuclear medicine imaging?
1. TLD badges and rings to monitor exposure to the body and hands
2. Designated prep area due to high activity called hot labs
3. Isolated ventilation, protective lead and lead glass shielding for vials and syringes, and gloves
106
# What is the difference between PET&SPECT imaging with;
Ring detectors
PET: Stationary ring detector
SPECT:Rotating detector
107
# What is the difference between PET&SPECT imaging with;
Collimation
PET:Electronic collimation
SPECT:Physical collimation
108
# What is the difference between PET&SPECT imaging with;
Half lives
PET:Shorter half lives
SPECT: Longer half lives
109
# What is the difference between PET&SPECT imaging with;
Production of radioisotopes
PET: Produced in cyclotron
SPECT: Produced in reactor, generator or cyclotron
