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Nuclear Medicine Flashcards

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1
Q

Outline brief outline of nuclear medicine process

A
  • Radiopharmaceuticals are taken internally, for example intravenously or orally.
  • Then, external detectors (gamma cameras) capture and form images from the radiation emitted by the radiopharmaceuticals.
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2
Q

What is 2D: Scintigraphy (“scint”)

A

2D: Scintigraphy (“scint”) is the use of internal radionuclides to create two-dimensional images.

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3
Q

What is 3D: SPECT

A

3D: SPECT is a 3D tomographic technique that uses gamma camera data from many projections and can be reconstructed in different planes.

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4
Q

What is Positron emission tomography (PET)

A

Positron emission tomography (PET) uses coincidence detection to image functional processes.

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5
Q

Give 2 clinical applications of PET

A
  • Neurological diseases such as Alzheimer’s and Multiple Sclerosis
  • Cancer
  • Effectiveness of treatments
  • Heart conditions
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6
Q

Which of the following statements about Nuclear Medicine (NM) is NOT true?

A.NM relies on physiological processes to provide an image

B.NM uses radiopharmaceuticals

C.NM is solely used for diagnostic purposes

D.NM includes both 2D and 3D imaging

A

C.NM is solely used for diagnostic purposes

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7
Q

Why doesn’t NM provide anatomical information?

A

•NM relies on physiological processes and hence provides functional information and NOT anatomical information

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8
Q

What are the 3 main steps in NM?

A
  1. A suitable radiopharmaceutical (or radionuclide) is introduced into the patient;
  2. The radiopharmaceutical is allowed to concentrate in a specific organ;
  3. The organ is scanned using an appropriate scanner, e.g. gamma camera
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9
Q

Give 2 things NM can do

A
  • •Physiological measurement
    • •Lung, heart, kidney, bone
  • •Diagnosis of primary tumours
  • •Diagnosis of secondary tumours (metastases)
  • •Radionuclide therapy
  • 2D- planar imaging technique
  • 3D- SPECT and PET
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10
Q

Give an overview of SPECT

A
  • Single photon emission computed tomography
  • Uses similar / same radiopharmaceuticals as 2D imaging
    • e.g. technetium based
  • Mode of acquisition changes
    • i.e. how the data is acquired and processed
  • Cross-sectional imaging
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11
Q

Give an overview of PET

A
  • PET (Positron emission tomography)
  • Different pharmaceutical to planar and SPECT imaging
  • FDG (Flurodeoxygluocose) (18
  • Radiopharmaceuticals decay by the emission of positrons
  • Annihilation – positron travels a few mm then interacts with an electron
    • Two gamma photons are emitted (511 keV)
    • 1800 opposed to each other
  • The camera detects gamma rays to produce the image
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12
Q

What type of nuclear instability results in positron emission?

A
  • -Too many protons
  • -Proton transformed into a neutron and a positron and neutrino are emitted
  • -A is unchanged, Z is decreased, so the daughter product is a different element
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13
Q

Which of the following statements about radioactive decay process is NOT true?

A.Gamma rays have higher energy than α and β particles

B.During α decay a helium atom is ejected

C.During β decay the particle ejected can have positive or negative charge

D.Gamma rays are negatively charged

A

D.Gamma rays are negatively charged

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14
Q

What are the 3 modes of decay

A
  1. •Alpha decay or alpha particle emission
  2. •Beta decay or beta particle emission
  3. •Gamma decay
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15
Q

What is the difference between Gamma ray emission and alpha or beta decay

A

Gamma ray emission (not particulate like alpha or beta decay

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16
Q

The physical half-life of Technetium-99 metastable is 6 h. How much activity is needed at 9 am if 80 MBq is needed at 9 am next day?

A.2000 MBq

B.1280 MBq

C.320 MBq

D.160MBq

A

B.1280 MBq

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17
Q

Define Biological half-life

A

•is the time taken for the concentration of a certain chemical in an organ to be reduced to half its original concentration.

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18
Q

Define Effective half-life

A

is the time taken for the activity of a certain radionuclide in a certain organ to be reduced to half of its original activity.

•1/t1/2(eff)=1/t1/2(phys)+ 1/t1/2(bio)

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19
Q

The diagram depicts various parts of a gamma camera. What is the name of the part indicted by red arrow?

A.Detector

B.Collimator

C.Photomultiplier

D.Filter

A

A.Detector

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20
Q

Describe the detector from a gamma camera

A
  • Scintillation crystal
  • Usually sodium iodide crystal doped with thallium
  • Converts gamma radiation into visible light
  • Inefficient process

About 10% of incident gamma radiation converted to light

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21
Q

Which of the following is a radiopharmaceutical that can be used to measure the kidney function?

A.Tc 99m Exametazime

B.Inulin

C.Tc 99m DTPA

D.Tc 99m Macroaggregated albumin

Study These Flashcards
A

C.Tc 99m DTPA

22
Q

What is technetium

Study These Flashcards
A

•Technetium is an radioisotope (gamma ray emitter) and DTPA is excreted by kidneys and hence allows the measurement of renal function (DTPA scan or renogram)

23
Q

Technetium is a radioistope, which has many radiopharmaceuticals associated with it.

True or False: The associated radiopharmaceuticals have the same clinical applications

24
Q

Which of the following radiopharmaceuticals is useful in positron emission tomography (PET) scan for detecting malignant tumours?

A.Technetium 99m DTPA

B.18-Fluorodeoxyglucose

C.Technetium 99m Pertechnetate

D.Technetium 99m HIDA

Study These Flashcards
A

B.18-Fluorodeoxyglucose

25
•FDG (Flurodeoxygluocose) (radiolabelled glucose analogue 18-fluorodeoxyglucose) What is it used to detect?
•Used for distinguishing benign and malignant tumours
26
What two broad things can NM tell us
* structural or anatomical location * functional or physiological information
27
What is an unstable nucleus
The strong nuclear forces do not generate enough nuclear binding energy to hold the nucleus together permanently and so it breaks down
28
describe alpha decay
* Spontaneous emission of an alpha-particle (consists of 2 neutrons and 2 protons) * The nucleus should have an A \>150 and must have too few neutrons for the number of protons * They have a short-range in tissue so have little practical application
29
Describe beta decay
* Nucleus should contain too many neutrons * Conversion of neutrons to protons and vice versa * A particle having a mass equal to that of an electron is ejected from nucleus * The particle may have either positive (positron) or negative charge (negatron)
30
describe gamma decay
Gamma ray emission = wave (not particulate like alpha or beta decay)
31
what is the decay scheme
The decay process may be in the form of a single step with one mode of decay or a multistep process with one or many modes of decay.
32
what are the ideal characteristics of a clinically useful radioisotope
* Have a short half-life * Emit gamma-rays of relatively low energy * Emit no particles * be added to the pharmaceutical without altering it’s chemical nature * Be readily excreted * Be easily generated
33
what is a gamma camera
* Specialised imaging equipment * Able to detect gamma photons * Does NOT produce radiation * Design is evolving continuously
34
what is the detector purpose in NM
* Scintillation crystal * Usually sodium iodide crystal doped with thallium * Converts gamma radiation into visible light * Inefficient process
35
what do staff need to be aware of when dealing with patients of NM
Patient becomes the radiation source- ejecting gamma emitters to the patients, making them ‘radioactive’
36
why may NM have a lower specificity than other imaging modalities
* Nuclear medicine relies on physiological processes to gain an image (e.g. glucose uptake), not anatomical composition. * Great sensitivity but not specific to the detailed anatomical locations
37
Give one benefit of NM
38
give one disadvantage of NM
Poor image quality (~ 1 cm resolution)
39
how is NM used to measure metastatic spread
* Inject technetium * Taken up by osteoblast- so measure the activity * Come back 3 hours later for gamma scan * Drink lots * Gives less cloudy picture * Reduces radiation dose/flushes through kidneys * Reduces radiation dose Sclerotic (osteoblastic activity) or nitic (osteoclast) metastases
40
what can NM be used to measure in orthopaedics
* Joint prostheses * Inflammatory disease and Paget’s (rheumatology) * Radiation Synovectomy
41
how can NM be used to measure infection
* Uptakes = infection? * Inject on tables (dynamic scan- see blood flow/increased) * Take 50mls of blood, remove white blood cells (label with gallium/indium) * Re-infuse = trace
42
how can NM be used in respiratory pathology identification
A mismatch in V/P quotient, indicates PE: 1. Breath in krypton gas/and administer technicism. 1. But difficult to breath in if you have a PE! 2. Ventilation is unchanged. 3. Alveolar spaces remain aerated. 4. Pulmonary arterial perfusion is reduced. 5. Thus, there is a mismatch of images (V/P quotient)
43
how can NM be used in GI pathology identification
* **Gastrointestinal Bleeding Study (with Tc99m - RBC)** * Detection and localisation of gastrointestinal bleeding, and occult bleeding including lungs, retroperitoneal, and peripheral sites. * Normal anatomy will take up lots of RBC’s as very metabolically active.
44
how can NM be used to assess gastric emptying
* Often to assess gastroparesis in diabetics. * Tc-99m radiolabelled meal given – e.g. scrambled egg white followed by jam on toast or milk for fluids vs solids * Sequences of images taken to assess the time taken for half the activity to leave the stomach
45
how can NM be used to assess liver function and pathology
* Tracking of bile flow through liver to gall bladder (if present) and then through to duodenum. * Various pathologies e.g. cholecystitis, Sphincter of Oddi dysfunction, post-operative bile leak. * Tc-99m HIDA given and patient imaged for up to 2 hours. May be given a fatty meal to empty gall bladder
46
how can NM be used to assess cardiac function
* Before transplant * Stress/Rest test or pharmacological ie. adenosine * Inject thallium or technicism then image via a SPECT scan immediately * Need to consider both stress and resting state- transient ischaemia in heart due to angina, so won’t perfused. Can then compare if there are any defects * May use second injection of thallium if rest can hasn’t re-perfused. To check if this is true or not.
47
what are the three basic radionuclides used in urology
1. filtered agents 2. excreted agents 3. cortical imaging agents
48
what can filtered radionuclides be used for in urology
Evaluation of: * perfusion of vascular supply * filtration (renal function) * drainage
49
What test would this be used instead of
micturating cystogram, as its better tolerated by children
50
What can NM be used to measure in endocrinology
* Thyroid disease * Thyrotoxicosis therapy * Parathyroid disease * Adrenal imaging
51
How can NM be used for the thyroid
Used to show extent of uptake prior to therapy and / or nodules and adenomas and carcinomas
52
How can NM be used in neurology- specifically in dementia care
Measure cerebral perfusion to map dementia

Medical Imaging (13 decks)

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