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RAD 412 > Imaging modalities > Flashcards

Imaging modalities Flashcards

1
Q

How do radiodense and radiolucent structures appear on medical images?

A

radiodense structures appear bright e.g bone

radiolucent structures appear dark

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2
Q

what are some advantages and disadvantages of x-rays?

A

ADV:
- quick
- accessible
- low cost
- low radiation dose

DIS:
- not as good
- uses radiation
- single 2D views

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3
Q

What is digital tomosynthesis?

A

three-dimensional mammogram that uses X-rays to obtain sectional images of the breast, which are then reconstructed into a 3D volume.

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4
Q

What is fluoroscopy cerebral anagram?

A

contrast injected into the carotid artery (major brain vessels that provide brains blood supply), which specified the cerebral arterial vessels

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5
Q

What does RF stand for and what does it do?

A

Radiography fluroscopy

continuous or pulsed x-rays produce a series of images

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6
Q

What imaging modality is used with fluoroscopy?

A

movable c-arm (may vary)

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7
Q

Discuss what happens when fluoroscopy contrast is swallowed

A
  • contrast is swallowed whilst pulsed X-ray taken
  • equipment may vary from c-arm

-multiple angles taken

-contrast followed down to stomach and traced through the bowels with static images

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8
Q

give some ADV and DIS of radiographic fluoroscopy

A

ADV:
- records multiple images
- can measure element of function
- guide for therapeutic procedures
- versatile

DIS:
- variable radiation dose
- 2D images usually
- most applications require contrast
- therapeutic procedure take time

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9
Q

Give some examples of why you might undergo a fluoroscopy

A
  • evaluation of GI tract
  • vessel angiography
  • sialography (tear ducts/salivary glands)
  • evaluate where contrast is injected
  • evaluate movement
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10
Q

What does US stand for?

A

Ultrasound

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11
Q

How does an ultrasound work?

A

sound waves reflected by changed in soft tissue density.

They originate from the probe and reflections also picked up

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12
Q

When will a high frequency or low frequency probe be better during an ultrasound?

A

high frequency probes excellent resolution at skin surface

lower frequency probes better depth penetration

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13
Q

Why is gel used in an ultrasound?

A

eliminates air interface with probe

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14
Q

Give ADV and DIS of ultrasounds

A

ADV:
- accessible than some
- mobile
- lowish cost
- no radiation
- view images in real time
- measure blood flow

DIS:
- reliant on operator skill
- only operator determined images saved
- air/bone interfaces limit deeper visibility
- reduced resolution of deeper structures

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15
Q

Why might an ultrasound be used?

A
  • antenatal evaluation
  • image abdominal organs/ vessels in abdominal symptoms
  • elevate musculoskeletal problems
  • soft tissue lumps and bumps
  • echocardiography (cardiac evaluation)
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16
Q

What does CT stand for?

A

Computed tomography

17
Q

How does a CT work?

A
  • x-ray source rotates count the patient
  • x-rays pass through the patient and are picked up by an array of detectors opposite the source
  • patient moves progressively though the scanner
  • cross sectional image data calculated from acquired raw data
18
Q

How many slices can a CT take in 350ms?
What pixels is it?

A

350ms for 16-320 slices
512x512 matrix

19
Q

What can 3D reconstruction from CT scans provide an advantage for?

A
  • provide useful info for operative planning
  • show medical imaging to those unfamiliar with it
  • used to create bespoke prosthetic implants and 3D printing
20
Q

What are some ADV and DIS of CT?

A

ADV:
- increasingly accessible
- large amount of info obtained quickly
- versatile
- 3D representation of anatomical areas
- visualise large number of anatomical structures well
- guide for interventional procedures

DIS:
- radiation dose
- other tests more accessible/quicker
- more expensive than some
- over utilised as a diagnostic test

21
Q

Give some examples of when you would use CT

A
  • Trauma
  • abdominal pain
  • chest pain
  • vasular pain
  • cancer staging
22
Q

What does MR stand for?

A

Magnetic resonance

23
Q

How does MR work?

A
  • patient placed in bore of scanner via motorised table
  • strong magnetic field permanently active
  • radiofrequency waves interact with protons within body

Protons spin on their axis, radio frequency waves are used to flip the aligned protons or align their spin.
The net magnetic moment can be measures.
T1 effects relate to proton flip.
T2 effects relate to proton spin alignment.

24
Q

What is MRI great for screening?

A

soft tissue or areas of inflammation/water content

25
Q

Give ADV and DIS of MRI

A

ADV:
- no radiation
- multiplayer imaging of any body part
- provides info on soft tissue that other modalities cannot
- wide variety of specialised use e.g blood flow

DIS:
- long scan time
- large magnet
- heating effects
- noise
- calustrophobia
- image artefacts common
- low accessibility and expensive

26
Q

When might you use an MRI?

A
  • neurological signs e.g brain or spine
  • assessing ‘lesions’ within various body organs
  • assessing joint soft tissue/ bones
  • evaluating heart
27
Q

`How is nuclear medicine imaging undergone?

A
  • preprepared radioactive tracer injected into patient
  • tracer accumulates in body system/anatomical regions based on tracer type
  • tracer emits gamma rays which are detected on gamma camera
28
Q

What does PET stand for?

A

positron emission tomography

29
Q

What is the tracer used in PET scans?

A

FDG, fluro deoxyglucose

30
Q

What is the half life of FDG

A

2 hours

31
Q

Why is FDG used as tracer?

A

its taken up by areas of high metabolic activity e.g cancer cells

32
Q

Why are PET and CT scans fused?

A

to add anatomical detail

33
Q

Give ADV and DIS of nuclear medicine scans

A

ADV:
- large scan coverage
- provides functional/metabolic aspect
- well tolerated
- wide ranging application

DIS:
- long scan times + multiple visits
- limited anatomical detail
- radioactive patient
- radiopharmaceutical prep

34
Q

When might you use NM scans?

A
  • blood clots in lungs
  • malignant spread to organs/systems
  • evaluating fractures
  • looking for infection
  • blood flow to organs
  • therapeutic use

RAD 412 (20 decks)

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