38. CT: QUALITY ASSURANCE

Question 1

1. What do CT vendors often provide?

Answer 1

• they provide a handbook of recommended
  Quality Assurance (QA) activities
• they also carry out routine preventative maintenance
• this is only if they are under contract

Question 2

2. How often do CA technologists perform Quality Assurance activities?

Answer 2

THEY CAN PERFORM THEM:
- daily
- weekly
- monthly

Question 3

3. How often do Qualified Medical Physicists perform Quality Assurance activities?

Answer 3

• Annually
• annually

Question 4

4. What is the Chief Physicist responsible for?

Answer 4

• the entire Quality Assurance program
• Remediation actions

Question 5

5. Who offers the general Quality Assurance Guidelines?

Answer 5

• national organisations
• international organisations

Question 6

6. What has the American College of Radiology set up?

Answer 6

• they have set up the accreditation program for CT

Question 7

7. What does the Accreditation Program foe CT invole?

Answer 7

IT INVOLVES THE EVALUATION OF:
- the individual CT as a facility
- all the interpreting physicians
- medical physicists
- technologists
- all those who work on the CT

Question 8

8. What happens if only the CT device, but not the entire facility, are accredited?

Answer 8

• re-accreditation is required
• every three years

Question 9

9. What are the three general categories that the Quality Assurance Tests deal with?

Answer 9

1. Sample Clinical Images
2. Measurements on a highly Specialised ARC CT
   Phantom
3. Dose Assessments with the CTDI phantom

Question 10

10. What needs to be submitted in order to do these 3 tests?

Answer 10

• the submission of a set of clinical images
  of various types
• details of the protocols that are used routinely at the
  facility

Question 11

11. What does the Second Category of tests involve?

Answer 11

• measurements on a specially designed ARC CT
  Phantom

Question 12

12. How many modules does the Phantom consist of?

Answer 12

• four

Question 13

13. What does the Phantom and its four modules asses?

Answer 13

1. THE AVERAGE HU VALUE FOR PURE WATER
   - for a range of machine operational settings
2. THE LINEARITY OF THE CT NUMBERS
   - along with the attenuation coefficients of a number of
   materials
3. IMAGE UNIFORMITY
   - Poisson noise throughout the field of view
4. LOW-CONTRAST RESOLUTION
   - by way of a contrast-detail test device
5. HIGH-CONTRAST RESOLUTION
   - down to 0.4 lp/mm

Question 14

14. What does the third category of tests call for?

Answer 14

• CTDI measurements for three distinct protocols

Question 15

15. What is the criteria for the imaging of an adult head with the small CTDI phantom?

Answer 15

• the adult head should yield a reading that is below the
  pass or fail criteria of 80 mGy

Question 16

16. What is the criteria for the imaging of an adult abdomen protocol with the large CTDI phantom?

Answer 16

• the CTDI vol has to be below 30 mGy

Question 17

17. What is the criteria for the imaging of a paediatric head with a phantom with the site’s standard paediatric setting ?

Answer 17

• the phantom must be below 40 mGy

Question 18

18. What is the criteria for the imaging of a paediatric abdomen with a phantom with the site’s standard paediatric setting ?

Answer 18

• it must be below 20 mGy

Question 19

19. Does this image make sense?

Answer 19

• yes

Question 20

20. Does this image make sense?

Answer 20

• yes