Brainscape's Knowledge GenomeTM

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


See full index

MRAD 251 - Computed Tomography > Week 4 Lecture 1 > Flashcards

Week 4 Lecture 1 Flashcards

1
Q

6 basic ct equipment

A
  1. couch/table
  2. operating console
  3. workstation
  4. contrast media injector
  5. accessory equipment
  6. gantry
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe some characteristics of the table.

A

it is made of carbon fibre to provide it with rigidity
it is controlled by electrical and mechanical controls
there are attachment areas for accessory equipments
it is narrow and concave

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

2 planes the table can move in

A
  1. vertical (y axis)
  2. horizontal (z axis)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

incrementation

A

when the table moves to a specified distance in the z axis plane

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

why is table motion important?

A

it can affect consistency of the scanning and pathology localization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

why is table referencing important?

A

it will help maintain scan consistency between followup exams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

scan point

A

table’s position relative to the gantry; gives you the location of irradiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

scan point should be manually set to _____ by technologist

A

zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

limitations to the table

A
  • weight restrictions
  • scannable range* (must be considered to prevent patient repositioning)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

*exceeding the weight limits of the table can…?

A

affect precision of pitch

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

operating console

A

pieces of equipment that allow technologists to input factors prior to acquisition that affect the scan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the monitors called at the operating console?

A

scan monitors & display monitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what makes up the operating console?

A
  1. computer
  2. keyboard
  3. multiple monitors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

the keyboard at the operating console enables?

A
  • communication with scan room
  • manipulation of gantry tilt
  • table movement
  • irradiation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

scan monitors

A

enables the selection of various factors prior to acquisition (ex. patient’s demographics, scan protocols and parameters)

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

display monitors

A

enables image viewing and post-processing functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what type of data is stored at the operators console?

A

RAW data

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

workstation

A

**access and manipulate IMAGE DATA; post-process images

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the key difference between the keyboard’s control on the operators console vs. workstation?

A

keyboard at operators console allows for communication with scan room, gantry tilts, table movement and irradiation

keyboard at workstation only communicates with the computer (*focus here is on image manipulation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

contrast media injector

A

mechanical device to safely administer large amounts of contrast media through an IV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

contrast media injectors can be programmed for?

A
  • to ensure precise volumes and injection rates
    *this allows for consistency of image appearance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

syringes on the contrast media injectors keep contrast and saline separate. contrast syringes need what special considerations?

A

a “warming sleeve”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

contrast media injectors have audible and visual alerts. why?

A

to help identify potential problems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

warming sleeves

A

*to maintain the desired temperature of contrast media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what does the contrast media injector comprise of?

A
  1. syringes (one or two)
  2. warming sleeves
  3. console
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

consoles on the contrast media injection devices are for?

A

allows for selection and monitoring
- selection of pre-programmed protocols and other administration factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

accessory equipments

A

designed to improve patient care and image quality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what are some accessory equipment commonly used in ct?

A
  • specialized headrest
  • sponges
  • immobilization straps
  • shielding
29
Q

gantry

A

houses the x-ray tubes + detectors
- opening the patient moves through

30
Q

what is the average diameter of the gantry aperture?

A

~70-90 cm

31
Q

what is the max gantry tilt?

A

30 degrees

32
Q

cephalad

A

towards the head/anterior

33
Q

caudad

A

towards the back/posterior

34
Q

what are the lights on the gantry for?

A

enables accurate patient positioning – isocenter

35
Q

what are the components you can find in the gantry?

A

x-ray tube, detectors, collimators, filtration, das, slip ring

36
Q

DAS

A

digital acquisition system
measures the transmitted radiation beam (ex. radiation flux at the detectors)

37
Q

what is sampling?

A

how DAS reduces the creation of image artifacts

38
Q

DAS converts measurements into? with what?

A

digital signals by using a ADC

39
Q

converted digital signals are sent to the computer by the ADC for?

A

reconstruction

40
Q

slip rings

A

electromagnetic devices that provides continuous electrical power and electronic communication across rotating surfaces

41
Q

what type of generators do conventional units use?

A

3-phase generators

42
Q

3 phase generators are found (inside/outside) the gantry

A

outside of the gantry

43
Q

what type of generators do the modern units use?

A

high frequency generators

44
Q

high frequency generators are found (inside/outside) the gantry

A

inside the gantry

45
Q

high-frequency inverter circuit

A
  • enables high kV settings
  • produces less voltage ripple (consistent power levels)
46
Q

what generator has better efficiency?

A

high frequency generators

47
Q

what are the two common sizes of focal spots?

A

0.5mm & 1mm

48
Q

how are the x-ray tube components designed in order to decrease heat loads?

A
  • higher anode rotation speeds
  • larger and thicker anodes
  • metal envelope
  • dual focal spots
49
Q

power supplied by high frequency generators (increase/decrease) heat loading.

A

decreases

50
Q

what is the common range for the high frequency generators?

A

120-140 kVp

51
Q

higher kVps = (fewer/more) electrons boiling off the filament

A

higher kVps = fewer electrons boiling off

52
Q

filtration

A

shapes the x-ray beam by absorbing low energy photons

53
Q

filtration results in (homogeneous/heterogenous) beam

A

homogenous beam

54
Q

by increasing the average energy of the beam, what does it do to the patient’s dose?

A

reduces it
(less to be absorbed by the patient)

55
Q

a consistent, uniform beam is good for?

A

increasing the accuracy of HU measurements

56
Q

**increasing the accuracy of HU measurements results in?

A

**minimizing the appearance of artifacts caused by beam hardening

57
Q

what are the two classification of filtration?

A
  1. inherent
  2. added (aka compensating)
58
Q

what are the 3 factors to inherent filtration?

A
  1. built into the system
  2. can’t be changed
  3. applied to all exams
59
Q

what are the 3 factors to compensating filtration?

A
  1. located between the tube and patient
  2. applied anatomically specific exams
  3. have special shapes to match beam divergence and patient shape
60
Q

collimators

A

small, thin pieces of lead that resemble shutters

61
Q

where are the collimators located?

A
  1. pre-patient (source)
  2. post-patient (pre-detector)
62
Q

why is the collimator needed post-patient?

A
  • to maintain beam width at the detector
  • decrease scatter that reaches the detector
63
Q

what does “narrowing the x-ray beam” mean?

A

restricting the x-ray beam to anatomy of interest, which allows for the controlling of the voxel length (z-axis)

64
Q

***collimators contribute to slice thickness in (SDCT/MDCT)
collimators control slice thickness in (SDCT/MDCT)

A

contribute - mdct
controls - sdct

65
Q

detectors

A

absorb transmitted radiation photons

66
Q

**detectors convert absorbed x-ray energy into _______

A

electrical signals

67
Q

radiation intensity (≠/=) electrical energy

A

radiation intensity = electrical energy

68
Q

detectors count the quantity of photons but not quality

A

quality = energy of the photons

MRAD 251 - Computed Tomography (13 decks)

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