Radionuclide Imaging

Question 1

Disadvantages of a radionuclide..

Answer 1

-Lacks diagnostic specificity
-Relatively poor resolution
-Relatively long scan times

Question 2

What does a Gamma Camera do?

Answer 2

Detects and measures the radiation that is emitted before the location is recorded

Question 3

Define Radionuclide

Answer 3

The nuclei of an atom that is unstable and tends to “fly apart”, emitting radiation (also known as radioisotope)

Question 4

What are some functions of Radioisotopes?

Answer 4

-Undergo spontaneous changes in their nuclei to either form a stable element -Become another radionuclide which undergoes further decay
-Breakdown and decay to cause alpha, beta and gamma ray/particle emission
-Undergo random processes that can be predicted and measured using radionuclide rates of decay

Question 5

What are 4 advantages of using radioactive substances?

Answer 5

-Target treatment to specific cells
-Find disease at its earliest stage
-Used for cancer, trauma and infection
-Monitors response to treatment

Question 6

What other advantages of RNI are there?

Answer 6

-Demonstration of rough anatomical structures, functionality of organs, size and shape of pathology
-Relatively low dose
-Highly sensitive to physiological/metabolical changes
-Determines how the body is functioning at a cellular level

Question 7

List 6 components of a Gamma Camera:

Answer 7

-Display Unit
-Amplifier
-Pulse Height Analyser
-Large Sodium Iodide Scintillator
-Photomultiplier
-Computer Processing Unit
-Collimator

Question 8

What is Spatial Resolution?

Answer 8

A measure of the smallest object that the imaging system can distinguish between. The smaller the holes in the collimator, the greater the SR but it cannot compare to X-ray SR

Question 9

What are the 3 routes of radionuclide disposal?

Answer 9

-Liquid: Drainage/sewer systems and sinks/toilets
-Solid: Incineration and landfill
-Gas: Fume cupboard and exhaust into atmosphere

Question 10

What properties do Scintillation crystals hold?

Answer 10

-High atomic density
-Fast conversion
-Good absorption
-Air and light proof containment (Hermetically sealed in an aluminium can)
-Low cost
-Transparent
-Efficient converter of radiation into light at an optimum wavelength for PMT sensitivity

Question 11

What does Sensitivity mean?

Answer 11

The amount of radiation getting through to the detector. The larger the holes in the collimator the greater the sensitivity.

Question 12

What is the half-life of Technetium (99mTc) and the area of interest it is used for?

Answer 12

-6 hours
- Salivary gland, Thyroid, Bone, Liver, Lung & Heart

Question 13

True or False?
I-131 is used for the Thyroid and has a half-life of 10 days.

Answer 13

False. I-131 has a half-life of 8 days

Question 14

What are 5 side effects of RNI treatment?

Answer 14

-Drowsiness
-Swelling of the throat, hands and feet
-Stomach pain
-Fainting
-Sensitivity to rapid temperature changes
-Fever
-Chills
-Difficulty breathing

Question 15

The ideal properties of a radionuclide are:

Answer 15

-Short half-life
-Cheap
-Readily available
-Non-toxic/allergenic
-Stable
-Good shelf life
-A single target organ
-Emits only Gamma radiation at 120-300KeV

Question 16

Which radioisotopes are inhaled into the lungs?

Answer 16

Xenon-133 and Krypton-81m

Question 17

Bones are the specific target organ for which radionuclides?

Answer 17

99mTc-MDP and 99mTc

Question 18

Collimator said have high attenuation due to lead plates which are either:

Answer 18

-LEAP (low-energy all purpose)
-MEAP (medium-energy “)
-HEAP (high-energy “)
-LEUHR (low-energy high resolution)

Usually parallel collimators

Question 19

Which radionuclide is subcutaneously administered into Lymph Nodes?

Answer 19

99mTc

Question 20

What are the safety guidelines after using Iodine 131?

Answer 20

-Drink at least 2 pints of fluid (water)
-Urinate sitting down and flush twice
-Avoid public transport
-Stop breast-feeding before starting treatment
-Pregnant women to avoid sharing utensils, food and having skin-to-skin contact
-Avoid contact with pregnant women and children

Question 21

How must the decontamination of spills be managed?

Answer 21

-Contain and avoid spread
-Notify RPS and prioritise injuries
-Decontaminate affected patients and staff
-Write incident report to RPA for evaluation

Question 22

What do the terms RPS and RPA mean?

Answer 22

Radiation Protection Supervisor and Radiation Protection Advisor

Question 23

What must be recorded first when dose is administered?

Answer 23

The absolute dose

Question 24

True or False?
After flushing with saline, not all measured dose goes into the patient as some is retained in the syringe.

Answer 24

True.

Question 25

What is essential to know when calculating the differential function of an organ?

Answer 25

Exactly how much radioactivity has gone into the patient.

Question 26

How do you calculate the absolute dose?

Answer 26

Original drawn up dose - Residual dose

Question 27

Why is the injected dose entered into the system?

Answer 27

So that differential function can be calculated.

Question 28

When is it especially important to calculate the differential function of a patient and why?

Answer 28

When treating paediatric patients because the dose levels are so low and the volume of injected radiopharmaceuticals are small (0.1ml)

Question 29

How long is the half-life of Gallium (67Ga) and what is the “target organ”?

Answer 29

78 hours and inflamed Tumours

Question 30

Explain the process of radionuclide combination.

Answer 30

-Combines with a carrier molecule to form a radiopharmaceutical
-Carrier molecules are selected to target specific organs/tissues
-Only small amounts and low doses are considered safe and diagnostic of precautions are taken