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Applied Medical Imaging > EXAM PREP > Flashcards

EXAM PREP Flashcards

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USMLE® Step 1 flashcards
1
Q

What is digital post processing? (smoothing)

A

Brightness values of pixels brought together.

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2
Q

What is digital post processing? (Edge enhancement)

A

Brightness can be increased along edges

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3
Q

What is the digital post processing? (Annotation)

A

Text on image

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4
Q

What is the digital post processing? (Subtraction)

A

Removal of background anatomy

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5
Q

What is digital post processing? (windowing)

A

adjust the image

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6
Q

What is digital post processing? (image reversal)

A

Bright and light pixels reversed

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7
Q

What is the digital post processing? (Magnification)

A

All parts of the image magnification

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8
Q

What limits digital post processing?

A

-You have to have a good quality (exposure index)

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9
Q

Film radiography artefacts?

A
  • Finger prints/finger nails
  • Static electricity
  • Clear Film (machine malfunction)
  • Black film- exposed to light
  • Clear film- Bubbles in chemicals
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10
Q

What is exposure index (EI)?

A

A value used to accurately determine whether you are giving the correct exposure value which is recommended for the examination.

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11
Q

What is noise?

A

Something that reduces the clarity of the image

Appears grainy/pixelated

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12
Q

What is window width?

A

Controls the contrast on the image (within a range)

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13
Q

What is the window level?

A

Controls the brightness on an image?

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14
Q

What is distortion?

A

Defined as: the misrepresentation ofobject size or shape as projected onto radiographic recording media.

Factors that affect distortion are:

  • Source Image Distance (SID)
  • Object Image Distance (OID)
  • Central Ray Alignment.
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15
Q

Signal to noise ratio?

A

The number of x‐ray photons that strike the detector (mAs) can be considered the “signal” : to the amount of x-rays that don’t reach the detector

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16
Q

How does air/gas appear on a x-ray?

A

Black

e.g lung, bowel and stomach

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17
Q

How does fat appear on an x-ray?

A

Dark grey

e.g subcutaneous tissue, retroperitoneal fat, blood vessels

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18
Q

How does bone appear on an x-ray?

A

Off-white

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19
Q

How does contrast/metal appear on an image?

A

Bright White

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20
Q

What is Bone processing assessment?

A 
B- bones, congruency of joints 
O- Opacities (white) Overlapping
L- Lucencies ( Black- fracture)
T- Trabecular
S- Soft tissue
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21
Q

What is the checking process after an examination?

A

I- identification
M- Marker locations correct

A- Anatomy correct in field

C- Collimation (changing shape of beam)
R- Rotation
E- Exposure index 
A- Additional requirements? (good image?)
P- Pathology (BOLTS)
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22
Q

Who do we need to check before MRI?

A
  • Patients
  • accompanying friends or family
  • visitors
  • patient support personal
  • ancillary
23
Q

T1 relaxation?

A

The processing of flipping protons from the transverse to the longitudinal axis (along the z axis).

24
Q

T1 recovery?

A

The time it takes to flip protons from the transverse to longitudinal

25
Q

T2 relaxation/decay?

A

-Flips on the x-y plane
-While it does this the protons de-phase, until completely out of phase
-At the same time giving off energy
(Fat de-phases fast, fluid slower)

26
Q

What is the difference between the RF coil and gradient coil?

A

Gradient coil–> Sends the RF pulse in causing excitation of protons
RF coil–> Receives RF signal from patient

27
Q

What does the faraday cage do?

A

MRI shielded in copper to stop RF going into the room and destroying the image quality (e.g Zipper)

28
Q

What is the CT number range for lung?

A

-830 to -200

29
Q

What is the CT number range for fat?

A

-30 to -250

30
Q

What is the CT number range for heart?

A

10 to 60

31
Q

What is the CT number range for brain?

A

20 to 40

32
Q

What is the CT number range for blood?

A

20 to 80

33
Q

What is the CT number range for liver?

A

20 to 80

34
Q

What is the CT number range for muscle?

A

35 to 50

35
Q

What is the CT number range for spleen?

A

40 to 60

36
Q

What is the CT number range for bone?

A

150 to 500

37
Q

What is the CT number range for bone (dense)?

A

350 to 1000

38
Q

What is the CT number range for Metal?

A

> 2000

39
Q

Artefacts of CT?

A

Streaks
shading
rings (old)
Distortion

40
Q

What is pre vs post collimation?

A
  • Determines slice thickness

- Determines the amount of scatter reaching the detector

41
Q

What is CR?

A

Uses a cassete. image is put in a plate and then it is displayed on an image display device.

Allows more effecint workflow does not use chemicals (like film).

Can do post processing

Allows a wider exposure range (than film)

42
Q

What DR?

A

Does not use cassetes or imaging plates. Image is generated at the detector and goes straight to the monitor.

The same detector can be used for the next patient.
With cassetes you had to choose the correct size and shape but with the detector its one size fits all.

Able to the post processing

Good storage - can be put on PACS.

Pateints need fewer repeats compared to film - because you can manipulate data unlike film.

43
Q

What is PACS?

A

Picture archiving computer system

44
Q

Where are the paramamary lymph nodes?

A

along the lateral aspects of breast tissue

45
Q

Describe three advantages?

A 
Image storage (increased space)
image transmission (easily transferring images for patients)
Image manipulation-  SEA SWIM
46
Q

List the four principles of a scout?

A
  • Should not be used for diagnostic purposes (low quality)
  • Sets the Limits for the CT SCAN
  • The couch moves at a low speed
  • Allows you to check if it can be used for planning (patient straight, gas, pathology)
47
Q

Benefit of multiple detectors?

A
  • Faste
48
Q

What are some common radiography artefacts?

A
  • Motion Artefact
  • Image impositioning (double exposure, two pts on one image)
  • Grid Cut off (field size)
  • Radio-oqague objects
49
Q

What is bright in T1?

A
  • Fat
  • Bone marrow
  • acute bleeds
  • contrast
  • Venous (slow flow)
50
Q

What is black (dark) in T1?

A
  • Air
  • fast flow (arteries)
  • Cortical bone
  • ligaments
  • Artefacts
51
Q

What is t1 mid-signal? (grey)

A
  • Muscle
  • fluid
  • hyaline cartilage
  • White matter is white
  • Grey matter is grey
52
Q

What is bright on a T2 image?

A
  • CSF
  • venous (slow flow)
  • Proteinous tissue
  • Fat (sometimes)
53
Q

What is dark on a T2 image?

A
  • Air

- Venous (fast flow)

54
Q

What is mid signal on T2 image?

A
  • Proteinous tissue
  • muscle
  • nerves
  • Grey and white matter opposite to normal

Applied Medical Imaging (3 decks)

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