Acquisition and Reconstruction Parameters Flashcards
1
Q
Acquistion parameters
A
- Collimator choice
- Zoom
- Acquisition mode
- Shape of orbit
- Matrix size
- Sampling interval
- Time per projection
- Total degrees covered
2
Q
Collimator choice
A
- crucial in maintaining sensitivity and resolution in SPECT imaging
- affects other parameters
3
Q
Zooming
A
- reduces FOV and increases pixel size
- improves resolution
- must consider truncation
4
Q
Truncation
A
- incompleteness
- not including entire body in image
5
Q
acquisiton modes
A
- step and shoot
- continuous step and shoot
- continuous
6
Q
Orbit shapes
A
- circular
- elliptical
- body contour
7
Q
Linear sampling interval
A
- # of pixels in a row across the matrix
- determines number of ray sums in a 2D count profile
- distance between sample points
8
Q
Angular sampling interval
A
- number of evenly spaced projections around a patient
- consider system resolution and matrix size
9
Q
Time per projection depends on..
A
parameters, counts vs. patient tolerance, other factors
10
Q
Sensitvity in depends on..
A
- the number of heads
- dual headed cameras are more sensitive than single headed camera because each head would only have to scan 180 vs. single head having to scan 360
11
Q
SPECT reconstruction
A
- 2D profiles are used to contruct a 3D representation
- each slice = one row of pixels in a projection
- thickness determined by the matrix size selected
- displayed as set of slices, rendered volume, or cine
12
Q
Reconstruction parameters
A
- matrix size
- slice addition
- reconstruction limits
- orientation
13
Q
Slice addition
A
- Addition of 2+ transaxial slices
- decreases data set size
- doubles pixel width
- halves number of rows
- same number of columns
- increases count density
- decreases axial resolution
14
Q
reconstruction limits
A
- set limits around organ or area of interest
- do not include entire FOV unless required
- ensure area of interest is not cut off
