Intro to Radiology

Question 1

The choice of which modality to use depends on… (3)

Answer 1

The clinical question
The body part
Patients age and sex

Question 2

2 modalities that

1. Use ionizing radiation
2. Do not use ionizing radiation

Answer 2

1. X-rays, CT

2. Ultrasound, MRI

Question 3

3 general steps of imaging

Answer 3

1. Signal is projected at or through body tissue
2. Tissue changes signal (absorbs, reflects, etc)
3. Changed signal provides info which is used to construct an image

Question 4

X-rays and CT scans map…

Answer 4

Tissue density

Question 5

Higher density tissues in X ray are termed…

Answer 5

Radiodense

Question 6

Lower density tissues in X ray are termed…

Answer 6

Radiolucent

Question 7

Fluoroscopy

Answer 7

Special type of X ray
Makes a movie rather than a picture
Black and white are reversed!
Can be used to show physiological processes like swallowing

Question 8

Interventional radiology

Answer 8

Specialty of radiology where minor surgeries are guided by x-rays

Question 9

3 strengths of X-rays

Answer 9

Relatively cheap
Readily available
Excellent bony detail

Question 10

2 weaknesses of X-rays

Answer 10

Some ionizing radiation (although low)

Poor soft tissue detail

Question 11

How does a CT scan work

Answer 11

Scanner rotates around the patient, taking multiple x-rays
Cross-sectional imaging
Can be reconstructed into different planes

Question 12

4 strengths of CT

Answer 12

Excellent bone detail
Good soft tissue detail
Ability to see each anatomic structure in 3 planes
Avaliable

Question 13

2 weaknesses of CT

Answer 13

More expensive than x-ray

Exposure to ionizing radiation

Question 14

Basic principle of MRI

Answer 14

No ionizing radiation
Patient placed in a magnetic field
External low energy applied to the patient
Each tissue absorbs and releases the energy at different, detectable, and characteristic rates
Image acquisition is multi-planar

Question 15

3 strengths of MRI

Answer 15

No exposure to ionizing radiation
Excellent soft tissue detail
Ability to see each anatomic structure in 3 planes

Question 16

4 weaknesses of MRI

Answer 16

More expensive than CT
Not readily available
Takes longer to take the images
Uses a very strong magnet

Question 17

3 types of contrast

Answer 17

For CT and MRI
Intravenous
Enteric
Intra-articular

Question 18

Ultrasound

Answer 18

Uses high frequency sound waves
Probe receives echoes from tissue interfaces in the body
Sound reflected by body structures is converted to an image

Question 19

4 strengths of ultrasound

Answer 19

No radiation
Relatively inexpensive
Real-time imaging
Portable

Question 20

3 weaknesses of ultrasound

Answer 20

Operator dependent
Difficult in larger patients
Takes time

Question 21

Imaging costs (from cheapest to most expensive)

Answer 21

X-ray
Ultrasound
CT
MRI