1 Flashcards
(104 cards)
0
Q
Afterglow
A
Flash of scintillation subtracted before image reconstruction
1
Q
Detector rows with various sizes
A
Adaptive array/ non uniform / hybrid rays
2
Q
Algorithm
A
Steps in a specific order to solve problem
3
Q
Attenuation profile
A
Attenuation properties that correlate position of rays
4
Q
Automated inj triggering
2 methods
A
Test bolus
Bolus triggering
5
Q
Step and shoot is also called
A
Axial
Conventional
Serial
Sequence
6
Q
Back projection
A
Converting —>attenuation profile—> matrix
7
Q
Beam pitch
A
Table movement per rotation % beam width
8
Q
B blockers
A
Reduces motion artifact on cardiac CTA images by lowering pts heart rate
9
Q
Bolus inj
A
Rapid inj of contrast done by hand or inj system
10
Q
Bolus phase
What phase is it?
A
Initial phase that follows iv bolus inj and arterial structures r filled with contrast
Not reaching venous structures
Bolus phase = arterial phase
11
Q
Bolus triggering
A
Use contrast bolus to initiate the scan.. Then uses a series of low xrt scans to monitor contrast bolus… Once level is enhanced table moves starting scan
12
Q
Capture efficiency
A
Detector obtaining photons passed through patient
13
Q
1cgy=
A
1rad
14
Q
100rads =
A
1 gy
15
Q
Clinical information systems
A
Systems that keep track of clinical data
16
Q
Clustered scans
A
Grouping more than one scan in a single breath hold
17
Q
Compensating filters
A
Reduce dose to patient and minimize artifacts
18
Q
Completed stroke / established stroke
A
Acute episode of interrupted blood flow to the brain
Lasts longer than 24 hrs
19
Q
Computed tomography dose index
A
Dose reported to FDA
20
Q
Cone beam is a what kind of detector
A
Multidetector row ct system
21
Q
Cone beam artifact are created how?
A
The larger the cone beam (detector channels) the more the effect
Artifacts that relate to the cone shaped beam for mdct helical scans
22
Q
Contiguous
A
One slice abuts the next
23
Q
Acquisition scan aka
And meaning
A
Aka: helical , spiral , volumetric
Means continuously rotating xraytube, constant output, uninterrupted table movement
24
Low contrast resolution
Objects with similar densities
25
Convolution
Filter
26
Ct angiography
How r scans done
Ct techniques used to c arterial and venous vessels thru body
Scans done in helical mode
27
How does Cupping artifact happen
Results from beam hardening
28
Data acquisition system (DAS)
Measures the number of photons that strike detector
| Converts info to digital signal then sends to computer
29
Delayed reaction
Contrast reactions that occur btw 1 hr - 1 week
30
Detector array
Collection of detectors in an arc
31
Detector pitch
Table movement per rotation time % slice thickness = detector pitch
32
DAC
| digital to analog converters
Changes digital signal back to analog format so that it's views on monitor
33
Direct axial plane
Positioning pt in specific position
34
Explain direct axial plane for foot
Plane parallel to plantar surface of foot
35
Display field of view
Section of info for display on image
36
Display processor
Assigns a group of HU to each shade if gray
37
Double contrast technique
Contrast and air out in joint space arthrography
38
Edge gradient effect
Irregularly shaped obj that hve a pronounced difference in density frm surrounding tissue
Streak or shading
39
Effective dies is written as
SV or rem
40
Ebonics stroke
Ischemic stroke
| A traveling particle that eventually become lodged
41
Embolism
Clot within vascular system that detaches frm original site
42
Equilibrium phase
Delayed phase
Phase of tissue enhancement after the iv inj of contrast media
Begins as early as 2 min after bolus phase or drip infusion
Equil phase is emptied into arteries and and soaked by organs
43
Excretory phase
Renal enhancement happens 3 min after iv
44
Fan beam
Is used on single row detectors
45
Helical interpolation methods
To tke slant and burr out if helical image
46
Hepatic arterial phase
First phase
| 15-29 seconds after bolus material
47
High contrast resolution and
| Aka
A.k.a. spatial resolution a.k.a. detail resolution
| The images seen as two separate forms.
48
High-frequency generator
Produces high-voltage and transmits it to the x-ray tube
49
Hi osmolality contrast media a.k.a. HOCM
It's a higher osmolality agent
50
HR CT high-resolution CT
CT of the chest is a technique used for assessment of lung parenchyma in patients with diffuse lung disease i.e. fibrosis and emphysema
51
Huber needle
Non-coring hook used to access implantable port
52
Hybrid arrays also called what and what are they
Detector rows variable widths and sizes
a. k.a. adaptive
a. k.a. nonuniform arrays
53
Hyperosmolar
Great number of particles in solution
54
Hypertonic
Great number of particles in solution
55
Idiosyncratic reactions
Unexplained reactions largely unpredictable, occurs within an hour of contrast administration, not related to delves.
56
Image data
Once computer has processed raw data assigning one HU value to each pixel
57
What is Raw data used for
raw data is used and then image reconstruction takes place
58
Image reformation? Image formation is also called what?
Image reformation is stacked across slices
generates an image in a plane orientation different from prospective image
a.k.a. image rendering
59
Image rendering
an image that is used to stack of cross-sectional slices and generates an image and a plane orientation different from prospective image
a.k.a. imagery formation
60
Input device
Computer hardware design to input information into the computer examples keyboard, mouse, plasma screen, CT detector.
61
Ischemic heart disease
One plaque builds up in coronary arteries
62
Isotropic
Equal in all directions
63
Iso tonic
Not having the same number of particles in a solution compared to blood
example iso tonic the word not in tonic
64
KV P the defines what
Quality of the beam how penetrating the beam is
65
MAS
Amount radiation
66
Kinetic energy
Energy in motion
67
Line pairs Phantom
Phantom used to measure spatial resolution
| It appears as closely spaced metal strips embedded
68
Linear attenuation coefficient
Amount of x-ray beam scattered or absorbed per thickness
69
Linear interpolation
Unknown point falls along a straight line between two known points
70
Metformin therapy
Given to non insulation dependent diabetics
71
Negative contrast agents
Contrast agent of lower density example: air or carbon dioxide.
72
Nephrogram phase
Renal enhancement that follows corticomedullary phase happens 100-120 seconds after IV
73
Nonequilibrium phase
Follow the bullets phase contrast brighter in the arteries ,parenchyma , and veins
Starts one minute after bolus injection
AKA Venus phase
74
Nonuniform arrays
Nonuniform arrays a.k.a.'s
Detector rows with variable widths and sizes
A.k.a. adaptive of AKA hybrid arrays
75
Partial volume artifact
Artifacts when the object is not appear all views
76
Unit of absorbed dose?
RAD's radiation absorbed dose
77
Quantum noise and quantum mottle
Insufficient number of photons are detected
Inversely proportional to image and noise. Image decreases noise increases the smaller the image gets the more noisy will see
78
Positive contrast agents
| two examples?
Contrast agents that are of higher density example barium or iodine
79
Portal venous phase
Enhancement that follows hepatic arterial phase
| Begins at 60 to 70 seconds after IV
80
Pixel
Picture element two-dimensional
81
Pitch formula
Table speed to slice thickness. The find is the travel distance of the CT scan table her 360° rotation of the x-ray tube divided by the X x-ray beam I'm collimation with
82
Peripherally inserted central catheters (PICC)
Long catheter inserted through a large vein of the upper arm located in the lower third of day S BC
83
Roentgen R
X-ray exposure in air
84
Scanfield of view SFOV
Scanned area of images where raw data is acquired
85
Ray sum
Detector senses Ray knows how much being attenuated
86
Scan parameters
Factors controlled by operator these factors are MAs, scan time, slice thickness, Silverview, reconstruction algorithm, and kv. Helical scans operator has choice of pitch.
87
Segmentation errors
Reformatted image one important vessels are inadvertently edited out
88
Seivert
Quality factor added to radiation dose new quantity is called dose equivalent
89
Slice misregistration
When patient breaths differently with each accusation information maybe missed due to this effect creates an incorrect anatomic position
90
Slice sensitivity profile
Slice thickness represented on ct image opposed to the size selected by the collimator
91
Slice thickness accuracy
Accuracy of slice thinkness selected by operator vs. width of collimator opening
92
Slice thinkness blooming
Slick thickness on imager wider than what selected
93
Slip rings
Brushlike apparatus providing continuous electrical power
Allows frame to continuously rotate
Eliminating need to straighten cables
94
Spatial resolution
Separate smll obj that are close together
95
Spatial resolution is what kind of contrast
High contrast resolution
96
Split bolus
Contrast inj techniques
Total dose is split in half
1st dose is given
Delay 2 min ( allows time for structures that are slower to enhance to b opacified)..
2nd bolus given containing remaining contrast
Scanning is initiated soon after the second inj is complete ( 2nd inj fully opacify the vessels )
97
Mild side effects
Heat
Nausea
Mild flushing
98
Test bolus
Scan delay administrating contrast
| Performing trials scans to determine length of time frm inj to peak contrast enhancement ie aorta
99
Third generation design
Produces fan shaped beam
100
Transient ischemic attack
| TIA
Reversible episode tiny emboli lodged in artery
101
Aliasing/ undersampling
Inaccuracies related to sharp edges and small objects
102
View
Complete set of Ray sums
103
When do windmill artifacts.
MDCT HELICAL SYSTEMS
