QA alternative tests leeds test tool

Question 1

QC recap in simple terms

Answer 1

to test if the equipment works properly

Question 2

8 common QA equipment tests

Answer 2

1. leeds test tool - contrast detectability
2. resolution
3. mechanical/ electrical and radiation safety
4. collimation and LBD alignment
5. radiation output
6. detector dose indicator monitoring
7. uniformity
8. erasure cycle

Question 3

what is the leeds test tool

Answer 3

a QA tool to check and calibrate equipment, ensuring consistent image quality by measuring resolution, contrast and performance stability

Question 4

what are the two main parts to the leeds test tool

Answer 4

• resolution
• contrast detectability

Question 5

what part of the leeds test tool is for resolution

Answer 5

Pb grating resolution bar pattern

Question 6

what part of the leeds test tool is for contrast detectability

Answer 6

discs and dots

Question 7

what is the objective of using contrast detectability and its frequency

Answer 7

to assess image quality by looking at the visibility of contrast details
- every 6-12 months

Question 8

How do you set up a leeds test tool contrast detectibility

Answer 8

• ensure the table and tube are level by checking angle indicators and place the leeds test tool on the image receptor
• centre the x-ray beam to the centre of the test tool object using 100cm SID and collimate
• attach copper filter to LBD
• expose on 70kVp and 16mAs
• repeat steps 1-6 for other image receptors
• repeat steps 1-6 for broad focus
• repeat steps 1-8 without copper filter

Question 9

what must you ensure for a contrast detectability test and all QA tests that involve making an exposure and evaluating an image

Answer 9

ensure you process the image using the correct software parameters according to the protocol

Question 10

how to assess contrast detectability

Answer 10

to assess contrast detectability, the circular discs and dots are counted. a mean number is calculated for both - fine and broad with and without the filter

Question 11

mean number of discs and dots reduces by 2

Answer 11

inform RPA / MPE

Question 12

what are discs used to assess

Answer 12

low contrast

Question 13

what are dots used to assess

Answer 13

high contrast

Question 14

what are the 10 white discs used to assess

Answer 14

greyscale

Question 15

3 objectives of resolution (FFS)

Answer 15

• to investigate unsharpness
• to measure the nominal (mm) and actual focal spot size (mm2)
• to measure resolution in line pairs/mm
• every 6 months

Question 16

how to set up for testing for resolution

Answer 16

• tube and table are level
• place tool on image receptor and rotate it 45 degrees
• centre tube to top of test tool at a 100cm SID
• collimate
• exposure at 50kVp and 4mAs
• repeat with other image receptors
• once processed score the number of resolvable groups of lines from screen
• use specification table for referencing
• repeat for broad focus
• repeat with tool positioned perpendicular to axis

Question 17

why does the tool have to be positioned perpendicular to the anode/ cathode axis when testing for resolution

Answer 17

to ensure that the scan lines of reader do not affect visualisation of the line pairs within test tool

Question 18

how many times does the resolution test must be done?

Answer 18

twice
- once with tool at 45 degrees to axis
- once with it perpendicular

Question 19

what does it mean if a group of 3 bars is resolved

Answer 19

when exactly 3 bars are clearly seen on image

Question 20

what can we work out if a group of 3 bars is resolved

Answer 20

• actual FSS (area hit on anode)
• nominal FSS (centre of ray at image receptor)
• angle of target

Question 21

what to look for when evaluating our radiation results

Answer 21

• number of line pairs should be monitored over time
• any significant changed to values recorded should be reported
• if line pairs visualised reduces by 2 - contact MPE/ RPA
• no radiation incident form required