Radionuclide Imaging

Question 1

What EMR is used in RNI?

Answer 1

Gamma rays

Question 2

What is the half life of Technetium 99m?

Answer 2

6 hours

Question 3

correct peak photon energy of Technetium 99m (Tc99m).

Answer 3

140 keV

Question 4

why Technetium is amalgamated with a variety of pharmaceuticals prior to being given or administered to a patient or service user?

Answer 4

To allow it to be targeted for specific organ/ cellular uptake.

Question 5

A photomultiplier tube does what?

Answer 5

A photomultiplier tube, receives light photons from the scintillation crystal in the gamma camera. These are detected by the photocathode that converts that “light” photons into photo/primary electrons which are multiplied through a series of dynodes eventually leading to the anode which gives this output as an electrical signal.

Question 6

All gamma cameras are dual headed for speed of acquisition.

Select one:
True
False

Answer 6

False

Question 7

What is the function of a Pulse Height Analyser?

Answer 7

To select the energies absorbed by the scintillation crystal that will be used to form the final image.

Question 8

What is Radioactivity?

Answer 8

Radioactivity is the rate of Decay of a nuclide

spontaneous emission of radiation

Question 9

GAMMA CAMERA HEAD

Answer 9

Collimator
Sodium Iodide crystal (NaI) Thallium activated
Light Guide
Photomultiplier tubes
Pulse height analyser
Positioning computer
Central processing Unit (CPU)

Question 10

Collimator function

Answer 10

…..

Question 11

why do RNI have separate waiting areas and

toilets?

Answer 11

This is because the patient is the radioactive source as they have been injected with the Radiopharmaceutical,
so they have separate waiting rooms to prevent other patients in different departments from being exposed to radiation doses.

Question 12

Why do RNI have Geiger counters?

Answer 12

To check if there has been a spillage of radioisotope anywhere in the department, e.g if a patient who was injected has used the toilet and got some pee on the floor this would be radiative,
this means that the toilet will have to be blocked off until the isotope has decayed to the level of background radiation so it’s safe for the cleaners to clean the toilet.

Question 13

Photomultiplier tubes function? How does it work?

Answer 13

Converts the light into electrical signal
Light hits the Photo cathode and the photocathode ejects an electron. It accelerates the electron at a dynode, the dynode amplifies the electron and leads to more. The electrons continue to bounce off the dynodes until it reaches the anode.
This means that for every 1 electron, 30 can be made. It is converted to an electrical signal and by increasing the number of electrons helps to improve spatial resolution

Question 14

What contradictions are required when using RNI?

Answer 14

Pregnancy

Breast feeding

Question 15

State which isotope is most commonly used, explain why this is useful.

Answer 15

Technetium99m
Good uptake into the target organ or system of organs
Rapid background clearance
Non-toxic
Appropriate half-life - Tc99m 60.02 hours
Easily imaged (photopeak energy) Tc99m 140keV
Availability
Easily labelled
Cheap (relatively)

Question 16

Describe understand how a range of RNI Images are produced.

Answer 16

…

Question 17

Acquisition modes

Answer 17

Planar – Collection of static views

Dynamic – Collection of rapid views (frames)

Gated – Collection of rapid frames based upon patient heart beats (ECG triggered)

Wholebody – Total body sweep “top to toe”

SPECT – Collection of step views as the camera heads rotate around the body – Tomography