51. NUCLEAR IMAGING: PULSE HEIGHT ANALYSER & COMPUTERS Flashcards
1
Q
- What happens after each Gamma Photon Interaction in the Crystal?
A
- the sum of the Digital Outputs
(from all the PMTs) - IS PROPORTIONAL
- to the energy of the Gamma Photon that strikes the
crystal
2
Q
- What is the Summed output of all the digital pulses (from the PMTs) called?
A
- the Z-pulse
3
Q
- With regards to input, what does the Pulse Height Analyser accept?
A
- it accepts only Z-pulses that correspond to the Gamma
Energy of Interest
4
Q
- What happens to each Z-pulse that the Pulse Height Analyser accepts?
A
- it is stored on the computer
- its location is stored on the computer
5
Q
- What can be inferred from this image?
A
THE CENTRE LINE:
- also known as the Peak
- holds the most useful information
ANY PHOTONS OUTSIDE OF THE WINDOW REGION:
- are removed
6
Q
- For which 3 reasons do we use Nuclear Medicine Computers?
A
- Acquisition
- Storage
- Processing of Data
7
Q
- How is the image data stored when it comes to Anger Camera Computers?
A
- it is stored in Digital Form
8
Q
- What happens when a Z-pulse is accepted by the Pulse Height Analyser?
A
FOR EACH Z-PULSE THAT IS ACCEPTED:
- a count is added to the Storage Location
- this location corresponds to its x and y co-ordinate
- this co-ordinate is determined by the Positioning
Circuit
9
Q
- How is the Digital form data storage visualised?
A
-it is visualised as a Matrix
10
Q
- What happens to each position in the Matrix?
A
- it corresponds to a Pixel
- this Pixel has a unique address
11
Q
- What does the Pixel Address composed of?
A
- it is composed of a row and column
- of the Pixel’s specific location
12
Q
- How is data digitised?
A
IT IS DIGITISED BY:
- assigning a matrix position to every accepted photon
13
Q
- Does this image make sense?
A
- yes
14
Q
- What happens when we have a greater number of Pixels?
A
- EACH PIXEL DECREASES IN DIAMETER
- this means that the pixel is smaller for the given field
of view - THE RESOLUTION OF THE IMAGE
- is preserved better
