CT

Question 1

What is CT?

Answer 1

• utilises an x-ray tube and a detector array rotating around the patient
• data collected is reconstructed into sectional/axial images

Question 2

What are the components of a CT?

Answer 2

• gantry
• table
• control console
• image processing

Question 3

What are types of scans?

Answer 3

• helical
• multi-slice
• sub-second
• CTA possible

Question 4

What is algorithm and kernel?

Answer 4

• mathematical approach to data representation in image

- manipulaition of actual data

Question 5

What is the standard CT window for cerebral tissue?

Answer 5

• WW: 100-150

- WL: 40-60

Question 6

What is the standard CT window for bone?

Answer 6

• WW: 2000-3000

- WL: 300-400

Question 7

What is the standard CT window for lung?

Answer 7

• WW: 1500

- WL: -600

Question 8

What is the standard CT window for mediastinal tissue?

Answer 8

• WW: 300-800

- WL: 50-80

Question 9

On a unenhanced scan what low density lesions are seen?

Answer 9

• ventricular density (cyst, centricular obstruction)

- oedema (abscess or infarct)

Question 10

On a unenhanced scan what high density lesions are seen?

Answer 10

• calcification

- haemorrihage `

Question 11

What are some data management challeneges?

Answer 11

• post processing slice width
• mutliplanar reconstruction
• shaded surface display
• volume rendering

Question 12

What is the role of CT in oncology?

Answer 12

• diagnosis
• staging TNM
• simulation for planning
• guidance for intervention
• monitoring response of treatment
• consider protocols

Question 13

What are some scanning parameters?

Answer 13

• scan plane/ patient position
• exposure factors
• pitch
• slice thickness
• scan extent
• table position and image orientation
• scan time
• subject contrast
• scan speed with respect to contrast