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Semester 1 - Body Logistics > 15. Medical Imaging > Flashcards

15. Medical Imaging Flashcards

1
Q

What are the 3 planes?

A

Sagittarius plane
Coronal plane
Transverse plane

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2
Q

What is the Sagitta plane?

A

anatomical plane which divides the body into right and left parts.

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3
Q

What is the coronal plane

A

vertical plane that divides the body into ventral and dorsal (belly and back) sections

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4
Q

What is the transverse pane?

A

an imaginary plane that divides the body into superior and inferior parts. It is perpendicular to the coronal plane and sagittal plane.

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5
Q

What are the different types of direction?

A
  1. Proximal - distal
  2. Lateral - medial
  3. Superior - inferior
  4. Anterior - posterior
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6
Q

What does proximal and distal mean?

A

Proximal - nearer towards body

Distal - further away from body

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7
Q

What does lateral and medial mean?

A

Medial- towards the midline

Lateral - away from the midline

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8
Q

What does superior and inferior mean?

A

Superior - top

Inferior - bottom

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9
Q

What does anterior and posterior mean?

A

Anterior - front

Posterior - back

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10
Q

What are the two types of plain film imaging?

A

X-Rays

Fluoroscopy

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12
Q

What is x-ray?

A

An electromagnetic wave

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13
Q

How do x-rays give an image ?

A
  1. Focused beam of high energy electrons
  2. These can pass through the body onto receiver
  3. But some are absorbed or scattered (attenuation)
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14
Q

What does attenuation depend on?

A

Depends upon density and atomic number (metals)

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15
Q

What does more dense or higher atomic number mean?

A

More Dense/Higher Atomic Number = More Attenuation = Lighter Appearance

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16
Q

What is the most dense tissue n the body?

A

Bone

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17
Q

What no longer acts as receivers of x-ray images?

A

Cassettes -create electrical signal when exposed to X-rays

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18
Q

Where are the x-rays electronically stored?

A

In PACS (picture archiving and communications systems)

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19
Q

What are the advantages of using cassettes and PAC rather than films?

A

◦ Zoom
◦ Alteration of Density
◦ Measurement of Distances
◦ Measurement of Angles

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20
Q

How do you read an x-ray?

A

Systematic Approach:

  1. Date Taken
  2. Patient Demographics
  3. Penetration
  4. View (PA/AP/lateral)
  5. Rotation
21
Q

What mnemonic is used to read a cast x-ray?

A

ABCDE

22
Q

What mnemonic is used to read an abdominal X-ray?

A

ABDO

23
Q

What are the advantage of using X-rays?

A

Quick
Portable
Cheap
Simple

24
Q

What are the disadvantages of X-rays?

A
  1. Radiation (but relatively low)
  2. One plane so two dimensional
  3. Would not see all pathology
  4. Can’t visualise all areas
  5. Poor soft tissue imaging
25
Q

Describe fluoroscopy

A

> Examination of anatomy and motion
Uses constant stream of X-rays
Often enhanced by contrast

26
Q

What is contrast?

A

Contrast – Barium, iodine or gadolinium (MRI)
◦ Strongly Absorb X-Rays – Dense White
◦ Any space it can be swallow, inserted or injected

27
Q

What are the uses of fluoroscopy?

A 
>Angiography
>Contrast GI Studies
>Therapeutic Joint >Injections
>Arthrograms
>Screening in Theatre
28
Q

What are the advantages of fluoroscopy?

A

> Dynamic

>Studies Cheap >Interventional Procedures

29
Q

What are the disadvantages of fluoroscopy?

A

> Clinician Exposure Must Be Minimised

>Radiation

30
Q

What are the two types of cross-sectional imaging?

A

> CT

>MRI

31
Q

Describe what happens in computed tomography?

A 
Rotating Gantry
◦ X-Ray Tube on One Side
◦ Detectors on the Other
Images put together by computer
Same Principle of Attenuation as X-rays
32
Q

What does a negative Hounsfield Units (HU) indicate?

A

Less Dense = Negative

33
Q

What does a positive Hounsfield Units (HU) indicate?

A

More Dense = Positive

34
Q

What are the advantages of CT scans?

A

> Quick

>Good spatial resolution >Can scan most areas (but not all)

35
Q

What are the disadvantages of CT scans?

A 
>Radiation
>Lower contrast resolution
>Affected by artefact
>Requires breath holding (not all patients may manage)
>Overuse (‘fishing for diagnosis’)
>Incidental findings
36
Q

What are CT scans used for?

A

> Diagnosis – Cancer, stroke, bony injury, blood flow

> Guide Further Tests or Treatment – Radiotherapy, biopsy

> Monitor Conditions – Cancer treatment

37
Q

How does MRI scans work?

A
  1. Strong, magnetic field 2. Aligns hydrogen atoms 3. Some point towards head and some towards feet
    ◦ But not 50/50
    ◦ Unmatched ions remain
  2. Radiofrequency pulse applied
  3. Unmatched ions absorb energy and spin in different direction
  4. Pulse is turned off and atoms spin returns which emits energy
  5. Computer processing to generate image
38
Q

What is MRI Weighting?

A

Different ‘relaxations’ produce different weightings from tissues

39
Q

What is the colour of fat and water in T1 weighting?

A

Fat is white, water is black

40
Q

What is the colour of fat and water in T2 weighting?

A

Water is white, fat is black

41
Q

In MRI scans, is white high or low signals?

A

White = High Signal

42
Q

In MRI scans, is black high or low signals?

A

Black = Low Signal

43
Q

What are MRI scans used to look at?

A

> CNS – Brain and spinal cord
Bones and Joint
Heart and Blood Vessels
Internal Organs

44
Q

What are the advantages of MRI scans?

A

> No Radiation

> Good contrast resolution

45
Q

What are the disadvantages of MRI sans?

A 
> Expensive
> Time Consuming
> Availability 
> Claustrophobic
> Some Patients Wont Fit
> Loud
> Need to Lie Still
> Metalwork (although lots now MRI safe)
46
Q

Describe Scintigraphy (Nuclear Medicine)

A

> Injection of radiopharmaceuticals
they Emit gamma rays which are detected to show where they are emitted from
Highly sensitive
provide Functional and anatomical information

47
Q

What are X-ray used for?

A
  1. Chest – Infection, pneumothorax, trauma, effusion, oedema
  2. Bowel – Dilatation, perforation
  3. Orthopaedic – Is there a fracture, trauma
  4. Post-Procedure – Nasogastric Tube, Pacemaker, PICC
  5. Dentist

Semester 1 - Body Logistics (16 decks)

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