Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Image science principles > RNI Equipment > Flashcards

RNI Equipment Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

which RNI procedure would be best imaged using a low energy ultra-high resolution collimator?.

A

MDP Bone scan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is responsible for converting gamma energy into light photons?.

A

the scintillation crystal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In Pet/CT radionuclides produce…

A

2 Gamma photons of 511 keV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

physical properties of Technetium 99m that make it ideal for radionuclide imaging.

A
  • relatively short half life
  • relatively short biological half life
  • relatively short effective half- life
  • non-toxic
  • can be administered to patient
  • gives off gamma radiation - 140kV
  • inert in patient’s body
  • stable in situ-
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Requirements for transporting radionuclide when injecting patient on the ward

A
  • radiographer wears PPE
  • needs to be transported via a syringe tube (surrounded in tungsten) or lead lined cradle
  • syringe needs to be labelled - patient’s details, radionuclide being used, Activity of radionuclide
  • Take something to store everything after you have used it
  • trained member of staff
  • never leave cradle unattended
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

safety requirements needed to perform injections

A
  • ID justifications
  • giving information about when the patient will be injected and what time the scan will occur
  • ensuring they avoid contact with children and pregnant women.
  • perhaps isolate patient - due to radioactivity
  • bringing spill kit and yellow bags for radioactive disposal for storage and spill clean
  • geiger counters to monitor any residual doses on our hands/ body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why do we use RNI?

A
  • to look at the area and whole functions of organs - can observe radiation uptake
  • monitor treatment i.e cancer treatment
  • can cater to those who cannot receive contrast. E.g. those who cannot have a CT IVU can have a MAG3 renogram
  • can be combined with 3D imaging - PET/SPECT
  • Selective uptake of radiopharmaceuticals by various bodily systems
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how does SPECT work

A
  • camera is set up to focus on a specific piece of anatomy
  • individual pictures are taken at 3 degree rotations
  • this is done until it reaches a 360 degree rotation
  • radiographer will overlay the images- creating a 3D image
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

components of a gamma camera (bottom to top)

A
  • collimators
  • scintillation crystals
  • photomultiplier tube
  • the amplifier
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

collimators are made of….

A
  • a Lead plate

- septa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

why are lead plates used for collimators?

A
  • they are inexpensive
  • have a high density
  • high attenuation coefficient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Septa in collimators

A
  • a series of small holes perpendicular to the face of the collimator
  • the smaller the holes and the more often they are, increases resolution - however, the scans take longer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

function of the collimators

A
  • to produce an accurate correlation between the emission of a gamma photon from the source and the position of the photon striking the crystal detector
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

collimators are dependent on the type of radionuclide used

A
  • low energy collimators (<150 keV) use Tc99m, TI201, I1213 ) - most commonly used
  • Medium energy (< 375 keV use In111,Ga67)
  • high energy (<500 keV use I131)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

types of low energy collimators

A

LEAP - low Energy All Purpose - used for MAG3 renogram
LEHR - Low Energy High Resolution
LEUHR - Low Energy Ultra High Resolution - used for bone imaging (metastes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

types of medium energy collimators

A

MEAP - Medium Energy all purpose

17
Q

types of high energy collimators

A

HEAP - high energy all purpose collimators

18
Q

if we increase the hole diameter in the collimator, what happens to the resolution and sensitivity?

A

resolution decreases

sensitivity increases - allowing more gamma rays through with a steeper angle

19
Q

if we increase the number of holes in the collimator, what happens to the resolution and sensitivity?

A
  • no change to resolution

- sensitivity improves

20
Q

if we increase the length of the holes in the collimator, what happens to the resolution and sensitivity?

A
  • resolution increases - rays are able to travel in straight lines
  • sensitvity decreases
21
Q

if we increase the septal thickness in the collimator, what happens to the resolution and sensitivity?

A
  • no change to resolution

- sensitivity decreases

22
Q

if we increase the object distance from the collimator, what happens to the resolution and sensitivity?

A
  • resolution decreases

- no changes to sensitivity

23
Q

collimators: spatial resolution

A
  • the ability of the imaging system to distinguish between 2 small points of activity positioned close together
  • the smaller the holes, the greater the spatial resolution
24
Q

collimators: Sensitivity

A
  • the proportion of photon icidents on the collimator, which passes theoght the detector
  • the larger the holes in the collimator, the greater the sensitivity (needed for function/uptake)
25
Q

scintillation crystal

A
  • sodium iodide activated with thallium NaI(Tl)
  • no self absorption
  • coated with a thin layer of aluminium: crystal is air-tight and light proof
  • transparent- so no self absorption
  • sensitive to rapid temperature changes - no more than 3 degrees per hour, or crystal will crack
  • 50cms in diameter
26
Q

what does the scintillation crystal do?

A
  • convert absorbed energy to light flashes
27
Q

scintillation length

A
  • short- to prevent overlap

- the intensity of light builds up quickly and then dies away in <1µs (decrease dead-time effect)

28
Q

crystal thickness

A

modern crystals are usually 9.3mm thick
- thicker crystals may reduce resolution
-

29
Q

crystal detection and absorption

A
  • 50 - 300keV range
  • if smaller than 50 keV, then the crystal wont have enough energy to scintillate
  • if higher than 300keV, then the photons will pass through the crystal without being absorbed, thus no scintillation
30
Q

function of a photomultiplier tube

A
  • converts the light from the scintillation event into electrical energy
  • they determine the location of each scintillation event as it occurs in the crystal electronic logic circuit
31
Q

dynode

A

an electrode in an electron tube that functions to produce secondary emission of electrons.

32
Q

Science behind PMT’s

A
  • light from the scintillation spreads in many directions and the nearest PM tube receives the most light
  • PMT’s all communicate in array
  • together, these signals give x and Y co-ordinates of the scintillation event
  • the x and y give the computer the plot to mark as an event on the image matrix
  • this process takes about 1 minute, however during this time the PMT cannot process another event - (dead-time)
33
Q

How does the Pulse Height Analyzer (PHA) work?

A
  • analyze the frequency distribution of the spectrum of photon energies that are captured by a gamma camera.
  • comes after PMT
  • exclude scatter rays
34
Q

PHA consists of…..

A

circuits which compare the relative pulse heights from individual tubes

  • uses a window of 15-20% of the peak energy value

Image science principles (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions