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CT Scan > CT COMPONENTS > Flashcards

CT COMPONENTS Flashcards

1
Q

the ring-shaped part of the CT scanner. It houses many of the components necessary to produce and detect x-rays.

A

Gantry

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2
Q

Characteristics of Gantry

A

APERTURE / BORE

TILTING RANGE

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3
Q

Most of the scanners have ____ aperture

A

70 cm

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4
Q

There are also scanners that have an ___ bore.

A

85cm

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5
Q

Tilting range of most scanners

A

+30 TO -30 DEGREES

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6
Q

tubes produce the x-ray photons that create the CT image

A

X-ray Tube

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7
Q

Atomic number of Tungsten

A

74

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8
Q

Anode Material used in xray tube for ct

A

Tungsten

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9
Q

Contain more than one size of focal spot

A

0.5 and 1.0 mm are common sizes

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10
Q

Because of ______ small focal spots in CT tubes produce sharper images

A

reduced penumbra

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11
Q

used to shape the x-ray beam

A

Filters

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12
Q

Reduce the radiation dose to the patient and help to minimize image artifact

A

Filters

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13
Q

helps to reduce the range of x-ray energies that reach the patient since xrays are polychromatic

A

Filters

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14
Q

Creates a more uniform beam intensity improves the CT image by reducing artifacts that result from beam hardening

A

Filters

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15
Q

Collimation in CT serves two purposes:

A

To reduce unnecessary dose to the patient

To ensure good image quality by reducing scatter radiation.

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16
Q

two types of collimation

A

prepatient collimation

postpatient collimation

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17
Q

In CT, we use ____ to collect the information.

A

detectors

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18
Q

a single element or a single type of detector used in a CT system

A

detector

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19
Q

used to describe the entire collection of detectors included in a CT system.

A

detector array

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20
Q

optimal characteristics of a detector

A 
High detector efficiency
Low, or no afterglow
High scatter suppression
High stability
High reproducibility
Wide dynamic range
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21
Q

TYPES OF DETECTORS

A

Xenon gas detector

Scintillation (solid-state) detectors

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22
Q

use high-pressure (about 25 arm) nonradioactive xenon gas, in long thin cells between two metal plates.

A

Xenon detectors

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23
Q

The long, thin ionization plates of a xenon detector

A

highly directional

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24
Q

must be positioned in a fixed orientation with respect to the x-ray source.

A

xenon detectors

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25
Q

is composed of a scintillator coupled tightly to a photodetector.

A

solid-state CT detector

26
Q

emits visible light when it is struck by x-rays, just as in an x-ray intensifying screen

A

scintillator

27
Q

an electronic device that converts light intensity into an electrical signal proportional to the light intensity.

A

photodiode

28
Q

SCINTILLATION CRYSTALS USED WITH PM TUBES

A

Sodium iodide –afterglow + low dynamic range ( used in the past)

Calcium fluoride

Bismuth germanate

29
Q

SCINTILLATION CRYSTALS USED WITH PHOTODIODE

A

Calcium tungstate

Rare earth oxides
Yttrium and gadolinium ceramics

30
Q

, to reduce crosstalk between adjacent detector elements

A

a small gap between detector elements is necessary

31
Q

DETECTOR EFFICIENCY

Gas detector

32
Q

Scintillation detectors

A

95% - 100%

33
Q

X-ray photons that strike the detector must be measured,
converted to a digital signal, and sent to the computer.
Positioned within the gantry near the detectors.

A

DAS (DATA ACQUISITION SYSTEM)

34
Q

Set of electronics between detectors and host computer

A

DAS (DATA ACQUISITION SYSTEM)

35
Q

DAS contains

A 
Amplifier
ADC, 
DAC, 
Generator
S/H.
36
Q

Signal from detectors goes to amplifiers for signal magnification and then is sent to sample/hold unit

37
Q

Located between amplifier and adc performs sampling and assigns shades of gray to the pixels in the digital matrix corresponding to the structures

A

Sample/Hold Unit (S/H)

38
Q

Converts analog signal output from the scanning equipment to a digital signal so it can be processed by a computer.

39
Q

shows the reading of the gantry tilt, table height, position of landmark, latch status, scannable range and tilt range

A

Display panel

40
Q

pressing this button will immediately stop every mechanical movement and X-ray emission

A

Emergency button

41
Q

incorporates several buttons mainly to control the movements of the gantry and table. Each front and rear cover has control panels.

A

Control panel

42
Q

this uses a halogen based laser beam marker to assist in proper patient positioning; breath navi is used to give visual breathing instructions to patients with hearing problems

A

Positioning light and breath navi

43
Q

for interacting with the patient

A

Microphone

44
Q

patient lies on the table (or couch, as it is referred to by some manufacturers) and is moved within the gantry for scanning.

A

Patient Table/Couch

45
Q

table is made up of a material with low atomic number such as _____ to avoid x-ray attenuation from the table itself.

A

carbon fiber

46
Q

The process of moving the table by a specified measure is most commonly called

A

incrementation

47
Q

incrementation is also referred to as

A

feed,
step, or
index

48
Q

Patient Table/Couch

DISTRIBUTED WEIGHT LIMIT

A

450 LBS (204 KG)

49
Q

Patient Table/Couch

COVERAGE FROM HEAD TO THIGH

50
Q

this moves in and out of the gantry aperture

51
Q

this is used to latch and unlatch the cradle and table accessories such as the head cradle and table extensions

A

Latch button

52
Q

is used to deliver oral instructions to the patient.

53
Q

placed at the foot of the table to control table movement.

A

Mat switch

54
Q

used as a patient restriciting device

A

Velcro straps

55
Q

OPERATOR’S CONSOLE

A 
Scan/Display monitor
Main Switch 
Keyboard and Mouse
Optical Disk Drives
Magnetic Disk Drives
56
Q

Used for patient scanning and image display

A

Scan/Display monitor

57
Q

CT Operating System

A

Windows

Linux

58
Q

Host Computer

A

Control of all components
Control of data acqusition, processing, display.
Data flow direction

59
Q

Image Display, Recording, Storage

A

Displays image ( output from computer)
Provides hard copy of the image
Facilitates the storage and retrieval of digital data
Communicates images in the network

60
Q

IMAGE RECORDING SYSTEMS (LASER PRINTERS)

A

Solid state laser printers

Gas laser printers

61
Q

Image Storage Media

A

Magnetic tapes
Magneto-optical disk (MOD)
CD

CT Scan (8 decks)

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