Imaging

Question 1

What are X-rays?

Answer 1

High energy electromagnetic radiation

Question 2

How are xrays created?

Answer 2

Release of electrons from a superheated tungsten cathode in a vacuum drawn towards tungsten anode at high speed - collision of electrons = heat and xrays

Bremsstrahlung / Braking radiation

Question 3

Which tissues absorb high proportions of xrays?

Answer 3

Tissues with high atomic nucleus

High beam attenuation (metal)

Question 4

What are the 3 different types of receptors in X-rays?

Answer 4

Conventional
Digital
Fluoroscopic

Question 5

Digital receptors substitute a cassette for which 2 types of radiography?

Answer 5

1. Direct

2. Computed

Question 6

What are the components of fluoroscopic receptors? 5

Answer 6

Input window
Input phosphorus plate
Photocathode
Accelerating anode
Output phosphor screen

Question 7

Factors to decrease exposure?

Answer 7

1. Decrease time
2. Max distance from surgeon
3. Xray producer further image intensifier closer (min scatter)
4. Shielding
5. Collimation (Reduction of window size)

Question 8

What does the MRI magnetic field do to the water protons in the body?

Answer 8

Align and synchronise spin

Question 9

What happens when a RF pulse is applied during an MRI?

Answer 9

Forces the protons to change alignment - tilt 90 degrees - transverse magnetization + synchronises precession

Question 10

What energy is used to create the MRI image?

Answer 10

Relaxation of the protons - energy released

Question 11

What is the spinning-top-like spin/ wobble of protons referred to in an MRI?

Answer 11

Precession

Question 12

What is a T1 image?

Answer 12

Time taken for magnetisation to return to the longitudinal axis after a RF

Question 13

What is a T2 image?

Answer 13

Time taken for protons to lose TRANSERSE magnetisation

Question 14

What is a T1 image good for?

Answer 14

Anatomy

Question 15

Which phase is gadolinium used for T1/T2?

Answer 15

T1

Question 16

What is a STIR?

Answer 16

Short tau inversion recovery

Question 17

What is a STIR good for?

Answer 17

Sensitive to abnormal fluid

Tumours and trauma

Question 18

What is a T2 image good for?

Answer 18

Pathology

Soft tissue

Question 19

How are ultrasound waves generated?

Answer 19

Electric current through a piezoelectric crystal

Question 20

What freq are ultrasound waves generated?

Answer 20

3-50MHz

Question 21

Units used to measure the attenuation coefficient in cT?

Answer 21

Hounsfield units

Question 22

Xray beam producing a collimated fan shaped X-ray beam that helically rotates around the patient?

Answer 22

CT

Question 23

How does a bone scintigraphy scan work?

Answer 23

Detects distribution of injected radio labelled tracer in gamma ray sensitive tissues

Question 24

Indications for bone scintigraphy? 4

Answer 24

Tumour
Infection
Mets
Occult/stress #

Question 25

Name the tracers used in bone scans?

Answer 25

Technitium 99 - OB
Gallium 67 - Inflamm proteins
Indium 11

Question 26

What are the 3 different phases in a bone scan?

Answer 26

Flow phase - nuclear angiogram
Blood pool phase
Static phase - bone activity

Question 27

What is a DEXA scan?

Answer 27

Dual energy X-ray absorbitometry

Question 28

Where are the 2 regions scanned in a DEXA scan?

Answer 28

Lumbar spine

Proximal femur

Question 29

What is a PET scan?

Answer 29

Positron Emission Tomography scan

Question 30

What is a PET scan capable of measuring?

Answer 30

Body function
Glucose uptake
Blood flow
02 consumption

Question 31

What are the 3 components in a PET Scan?

Answer 31

Cyclotron
Camera
Computer