2 - Aldridge - Imaging

Question 1

Ionizing Radiation Methods?

Non-Ionizing Radiation Methods?

Answer 1

Ionizing: Radiohraphs (x-rays, conv. films), Fluoroscopy, Computed Tomography (CT)

Non-Ionizing: MRI, Ultrasound (US)

Question 2

Conventional Radiographs/Plain Films

(x-ray)

Answer 2

No added contrast material

Energy detection by film or digital detector

Images named w/consideration to the direction of the X-ray beam

Question 3

X Ray Absorbance

Answer 3

Based on density of tissue, very dense will not allow X-rays to pass through, white, called radiopaque / radiodense

Low density, more will pass, black image–radiolucent

Gray somewhere in between

Question 4

5 Basic Densities on Radiographs

Answer 4

Question 5

What is an issue with the dimensions for radiographs?

Answer 5

Radiographs are a 2D projection of a 3D patient and flatten everything, multiple views are needed

Question 6

Advantages to Plain Films?

Disadvantages to Plain Films?

Answer 6

(+) Fast, cheap, mobile machines, most common

(-) Radiation, not good for pregnant, soft tissue not very good

Question 7

Fluoroscopy

Answer 7

Continuous x rays pass through

Barium swallow

real time

apparatus placement in surgery

Question 8

Computed Tomography (CT)

Answer 8

Similar to radiograph (uses ionizing radiation)

Source rotates 360 deg

multiplanar images

Computer renders final image

Question 9

How do you read CT?

Answer 9

Patient laying down, face up, your standing at their feet looking through their body

Question 10

Hounsfield Units

Answer 10

Measurement of CT density

Dense = higher number = white = increased attenuation

Less Dense = lower number = black = decreased attenuation

Question 11

CT Windowing

Answer 11

Post-processing that allows manipulation of multiple layers of at once

Question 12

CT Scans and Contrast

Answer 12

Can be performed with or without contrast

With = enhanced

Iodinated contrast used via IV, better distinguishing of structures

Iodinated contrast can have adverse effects and serious reactions in some people (kidney failure)

Question 13

CT Advantages and Disadvantages

Answer 13

(+) Resolution excellent (small fractures), multiple planes, widely available, cheaper than MRI, fast, multiple windows

(-) High radiation, IV contrast can be bad for kidneys, much more expensive than Xray

Question 14

MRI

Answer 14

Not use ionizing radiation, uses radio waves

Computer manipulates pulse data from electromagnetic wave radiation

Question 15

Weighted MRI Images

Signal Intensity?

Answer 15

T1 = anatomical detail

water = dark

T2 = pathological lesions

water = bright

• -

Increased Signal Intensity = white or bright area

Decreased Signal Intensity = black or dark area

Question 16

MRI Advantages and Disadvantages

Answer 16

(+) No radiation, multiple planes, better soft tissue than CT

(-) Not manipulated on viewing screen like CT, claustrophic/fat ppl bad, long-time, metal/implants can’t be scanned, no movement, expensive, contrast reactions

Question 17

MRI Safety

Answer 17

Can’t be around anything:

ferromagnetic, electronic, anything not certified MRI compatible

Magnet is always on

Metal than can’t move = not an issue (fillings, orthopedic hardware)

Metal than can move = issue (metal in eyes, old aneurysm clips)

Old Pacemakers = could drain battery, dork up coding, fire erratically

Question 18

Nephrogenic System Fibrosis (NSF)

Answer 18

Can occur if patients who are renally compromised are given gadolinium-based contrast agents

Question 19

Ultrasound (US)

Answer 19

Uses high frequency sound waves

Dense = sonodense = bright/white

Less Dense = sonolucent = dark/black

Question 20

Ultrasound Advatages and Disadvantages

Answer 20

(+) Noninvasive, no radiation, real-time, no discomfort, cheap, portable

(-) Bone and air-filled structures interfere, difficult w/obese patients

Question 21

Radiation Exposure

Answer 21

Large doses can be baaad, mkay?

Shield eyes, gonads, thyroid

Avoid X-rays on pregnant people