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Previous TQ's Flashcards

Edumacate yourself

1
Q

What type of radiation are X-rays?

A

Electromagnetic & Ionizing

Poduced in the x-ray tube

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2
Q

What is controlled by mA?

A

The amount of current (# of electrons)

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3
Q

What is adjusted with kVp?

A

The potential difference between cathode and anode

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4
Q

What is the photoelectric effect?

A

Most important type of interaction.

Photons are completely absorbed, no scatter produced

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5
Q

Is the photoelectric effect x-ray energy high or low?

A

Low energy, absorbed by tissue does not contribute to the image

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6
Q

What is PE inversely proportional to?

A

the third power of the photon energy (1/E^3)

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7
Q

Why is PE important?

A

Amplifies the differential absorbtion of x-rays between tissues. With out it there would be no image contrast.

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8
Q

What is compton scattering?

A

High energy Most important source of film fogging & personell exposure

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9
Q

What is acoustic impedance (Z) of a tissue the product of?

A

It’s physical density (p) and sound velocity (v) with in it.

Z=p*v

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10
Q

Define: Anechoic

A

Black, no signal/echo

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11
Q

Define: Hypoechoic

A

Dark grey

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12
Q

Define: Echogenic

A

Medium grey

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13
Q

Define: Hyperechoic

A

White

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14
Q

What is acoustic shadowing?

A

Appears as a dark band deep to gas containing, bone, mineral or metal structures

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15
Q

On ultra sound what color is fluid?

A

anechoic (black)

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16
Q

What is acoustic enhancement?

A

Happens when imaging deep to structures of low attenuation (fluid). Area under fluid will appear lighter (hyperechoic)

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17
Q

What constitiutes artifacts?

A

Acoustic Shadowing Acoustic Enhancement Mirror Images Slice Thickness Edge Refraction Reverberation (comet tail) Anisotropic Effect

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18
Q

What is the Hounsfield Unit scale?

A

Water - (baseline) 0HU

Bone - +1000 HU

Air - - 1000 HU

Soft Tissue - + 0-100 HU

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19
Q

How are HU displayed?

A
  1. Shades of Grey
  2. Must Window (ST, Bone, Air) b/c humans can only see 90 different shades
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20
Q

T1 vs T2

A

T1 - fluid is dark (hypointense)

T2 - fluid is bright (hyperintense)

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21
Q

What are the MRI sequences?

A
  1. Spin echo/Fast spin echo: T1, T2
  2. Inversion recovery: STIR (fat suppression), FLAIR (fluid suppression)
  3. Gradient Echo
  4. Proton density (PD)
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22
Q

What is PD MRI good for?

A

Good anatomical detail. Fluid higher signal than in T1, bone, tendon, ligaments are hypointense, fat signal high. Good for fluid vs soft tissue (better than T1)

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23
Q

What is T1 MRI good for?

A

Good anatomical detail, High fat signal, low fluid signal = cortical bone, tendons, ligaments hypointense

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24
Q

What is T2 MRI good for?

A

Poorer anatomical detail, fluid hyperintense, bone, tendones & ligamnets hypointense, fater med-high signal. Good for differentiating fluid from ST

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25
What is STIR MRI good for?
Hyperintense fluid - used to sppress fat (BM dark) --\> detects abnormal fluid in bone, medulla & ST
26
What is the contrast material for MRI?
Gadoliium (IV) has magnetic properites. It highlights lesions (hyperintense) Admin at end of plan sequence and run T1 again
27
What is the radiopharmaceutical used in **Scintigraphy**?
Technetium | (99mTc)
28
What agent is used for bone scans?
MDP | (Methyline Di-Phosphate)
29
List the 3 Imaging Phases of a **Bone Scan**.
* Phase I: Vascular or pool phase * Phase II: Soft tissue phase * Phase III: Bone phase
30
Characteristics of the Vascular phase of a bone scan?
* _Area imaged_ = vasculature & extravascular fluid * Very short phase * Only 1 area can be imaged * Best real-time
31
Characteristics of the Soft tissue phase of a bone scan.
* Distributed in the ECF of all body tissues * Occurs 1- 15 min post injection
32
Characteristics of the Bone phase of a bone scan.
* IDs pathological increases in blood flow & bone pathology * Occurs 2-4 hrs. post injection
33
How is the image formed in Scintigraphy?
* Gamma camera records radiation emitted from P * Photomultiplier tube inside the camera transforms the light into an electric signal * Intensity of radiation = pixel brightness
34
What does **99mTcO4** allows you to visualize?
Thyroid morphology
35
What does **131I** or **123I**  allow you to visualize?
Thyroid fxn
36
What type of energy is recorded by PET scan detectors?
anihilation radiation | (sounds dangerous!)
37
What is the advantage of PET scans?
* PET detectors are more sensitive & thus can detect very subtle pathologies * Functional imaging → agent accumulates in areas w/ high glucose metabolism (1° tumor & their metastasis) * Can study brain fxn
38
Which type of bone *lacks* radiographic density?
Cancellous/Trabecular/Spongy bone
39
Which form of bone is more dense radiographically?
Compact or Cortical bone
40
How do long bones gain length?
Endochonral bone growth along growth plates
41
Where are the **1° Ossification Centers** located?
Diaphyses | (middle of bone)
42
Where are the **2° Ossification Centers** located?
* Epiphyses (ends of bone) * Metaphysis
43
What are the weakest parts of developing bone? Consequence?
* Physes * Physeal FXs are common in young P
44
What does the shape of the physis partially determine? (In regards to FXs)
Type of Salter-Harris FX
45
Characteristics of **Benign Bone Lesions**?
* Short zone of transition * **distinct margins,** **sclerotic border** * Intact cortex * Intact, smooth periosteal new bone * Slow changes in appearance
46
Characteristics of **Malignant Bone Lesions**?
* Long zone of transition * I**ndistinct margins, less dense border** * Interuppted cortex * Interuppted, irregular periosteal new bone * Changes appearance rapidly
47
Is this lesion benign or malignant?
Benign
48
Is this lesion Benign or Malignant?
Malignant
49
What is the best way to confirm a **Chip FX**?
Radiograph the opposite limb & compare
50
What type of FX line is demonstrated here? What typically causes this type in animals?
* Comminuted FX w/ a **Transverse FX line** * High energy trauma → HBC
51
What type of FX line is seen here?
Oblique FX line
52
What type of FX line is seen here?
Spiral FX line
53
What are Comminuted FXs?
* Have at least three fracture fragments & the fracture lines interconnect. * The individual fracture lines that form the comminuted fracture may be transverse, oblique, or spiral.
54
What type of FX is seen here?
Comminuted FX
55
What type of fracture is seen here?
**Butterfly FX** (fragment)→ type of Communited a bone break in which the center fragment is contained by two cracks & forms a triangle.
56
What type of FX is shown here?
Multiple segmental FX | (type of Comminuted FX)
57
How do **Avulsion FXs** typically occur?
when a fragment of bone tears away from the main mass of bone as a result of physical trauma (often at the site of tendon & ligament attachement)
58
What type of FX is seen here?
Avulsion FX
59
What type of FX is seen here?
* **Greenstick FX** * occurs when a young, soft bone * One side bends and the other side breaks
60
Which **Salter-Harris Type** is shown here?
Salter-Harris **Type I** | (seperation @ the level of the physis)
61
What Salter-Harris Type is shown here?
Salter-Harris **Type II** | (involves the physis & metaphysis)
62
Which Salter-Harris Type is seen here?
Salter-Harris **Type III** | (involves the physis & epiphysis)
63
Which Salter-Harris Type is seen here?
Salter-Harris **Type IV** (involves physis, metaphysis & epiphysis)
64
Which Salter-Harris Type is seen here?
Salter-Harris **Type V** (crushed/compressed physis) (May not be visisble @ time of injury) (May lead to abnormal growth/deformity)
65
What type of physeal FX is seen here?
Salter-Harris **Type VI**
66
What type of Physeal FX is seen here?
Salter-Harris **Type VII** (AKA Ogden VII) * Isolated to the epiphyseal plate→ does NOT involve the physis * May be an avulsion fx
67
What are the features of a **Pathological FX**?
* Cortical thinning or destruction * Medullary bone cystic/destruction * Periosteal new bone is present * Shape/pattern/direction of FX line is unusual * Bone shape is often abnormal
68
What is the likely cause of this fracture?
Pathologic FX
69
What do transducers do?
Emit & recieve ultrasound Frequency is determined by the crystal used & inherent to each transducer
70
What is B-mode on the US viewing screen?
A multitude of recieved echos translated to a greyscale image
71
How does the image form in B-mode US?
the depth of echo is determined by time between emission & return & amplitude o echo is encoded as a grey scale value (High amplitude echo = bright/hyperechoic & Low amplitude echo = less bright/hypoechoic)
72
What has MRI done for diagnostic imaging?
Revolutionalized imaging for inracranial and soft tissue pathology due to it's excellent ST contrast
73
What are Gradient Coils?
1. Signal localization requires application of gradients in x,y & z planes. 2. Magnetic gradients are built into MRI gantry/magnet housing 3. Basis of spatial localization signal 4. Allow localization of slices & define slice thickness
74
What is Resonance in an MRI?
Radio frequency pulse applied at precessional frequency--\> H+ flip and align with field --\> at flip angle of 90\*, H+ spin in phase --\> Induce electric signal in reciever coils --\> RF pulse ends--\> spin loses coherence (relaxation) --\> T1 & T2 relaxation can be differentiated
75
How is the image formed in Scintigraphy?
* Gamma camera records radiation emitted from P * Photomultiplier tube inside the camera transforms the light into an electric signal * Intensity of radiation = pixel brightness
76
What is proportional to **Tc uptake** in Scintigraphy?
Tc uptake is proportional to the intensity of radiation
77
What is a "hot spot" on Scintigraphy?
An area of increased uptake = increased bone/soft tissue activity
78
Where is the **physeal plate** located?
Btwn the epiphysis & metaphysis
79
Where is the **Epiphyseal Plate** located?
Beneath the surface of Articular cartilage
80
What is the **"cut back" zone**?
* Site of marked modeling in width in the Metaphysis→ cortical margin is irregular * Has a roughened cortical/periosteal border * In young, growing animals
81
How do growth plates appear on rads?
appear poorly organized
82
What are the weakest parts of developing bone? Consequence?
* Physes * Physeal FXs are common in young P
83
How are CT images created?
By converting attenuation values (how much x-ray is absorbed by patient) via math & using filtered back projection into greyscale images
84
What is a helical CT scanner (1989+)?
1. Continual rotation of x-ray tube (faster) 2. Volume of data collected (greater) 3. Flexibility of 3D reconstruction
85
What are some advantages of CT vs X-ray?
1. Cross Sectional overcomes superimposition 2. Very high contrast resolution = differentiat ST from fluid and other types of ST 3. 3D reconstruction w/ thin slices 4. Can do contrast studies of vasculature
86
What are some disadvantages of CT?
1. Increased radiation dose 2. Expensive 3. GA needed 4. Not readily available 5. Specialist training to read images 6. Whole body scans not automatically diagnostic
87
How is attenuation expressed in CT?
Hounsfield Units
88
What are the basic principles of MRI?
1. Magnet creates external mag feild. 2. Pt. aligned w/ feild 3. Majority of body tissue is H2O 4. Tissue H+ acts as magnetic dipoles 5. Majority align with external mag field, in axis or opposite 6. H+ dipoles spin like a top around their own axis (precession) 7. H+ spin & precess at specific frequency that depends on feild strength (larmor frequency)

Diagnosit Imaging (2 decks)

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