Quality Assurance and Fault Analysis

Question 1

What does quality assurance program cover

Answer 1

procedures
staff training
x ray equipment
patient dose
image processing
display equipment 
image quality

Question 2

When should digital image receptors be checked

Answer 2

they are reusable and therefore susceptible to wear tear and mishandling

check regularly - every 3 months

Question 3

What are things to check on the digital image receptor

Answer 3

receptor itself
imager uniformity
image quality

Question 4

What do we look or on the receptor

Answer 4

check for visible damage to casing/wiring

check if clean (no congealed disinfectant or saliva)

Question 5

How do we check image uniformity of digital receptor

Answer 5

expose receptor to an unattenuated x ray beam and check if resulting image is uniform
should be consistent shade of grey

Question 6

How do we check image quality of digital receptor

Answer 6

take a radiograph of a test object and assess the resulting image against a baseline

Question 7

What does scratches on phosphor plate appear as

Answer 7

white lines

Question 8

What does cracking from flexing the phosphor plate result in

Answer 8

network of white lines

Question 9

What does delamination of phosphor plates result in

Answer 9

white areas around the edge

Question 10

What is delimitation

Answer 10

separation of phosphor layer from base plate

Question 11

If there is sensor damage to the solid state sensor what can this result in

Answer 11

square/straight lines

Question 12

If there is damage to sensor’s blasting casing what can happen

Answer 12

can get damage to more delicate components and may get dead pixels

Question 13

How does damage to film often present as

Answer 13

black marks due to sensitization of radiographic emulsion

however may appear white if emulsion is scraped off

Question 14

What may marks on film represent

Answer 14

nail marks
bite marks
finger prints

Question 15

What is a step wedge

Answer 15

one type of test object used to check image quality and contrast
self made or provided by manufacture

Question 16

What is a step wedge made of

Answer 16

overlapping layers of lead

Question 17

How do you use a step wedge

Answer 17

expose to a normal clinical exposure
compare image ot baseline
carry out regularly

Question 18

What is the aim of QA of clinical image quality

Answer 18

ensure radiographs are consistently adequate for diagnosis

Question 19

What are the 3 parts of QA of clinical image quality

Answer 19

image quality rating
image quality analysis
reject analysis

Question 20

What is image quality rating

Answer 20

grading each image

Question 21

What is image quality analysis

Answer 21

reviewing images to calculate success rate and identify any trends for suboptimal images

carried out periodically (every 4 months you review the last 150)

Question 22

What is reject analysis

Answer 22

recording and analysing each unacceptable image

Question 23

What is the quality ratings

Answer 23

diagnostically acceptable

diagnostically unacceptable

Question 24

What is diagnostically acceptable

Answer 24

no errors or minimal either in either px prep, exposure, positioning, image processing, image reconstruction and sufficient image quality to answer clinical q

Question 25

What is diagnostically unacceptable

Answer 25

errors in the list from before meaning image can't be used for diagnosis shouldn't be greater than 5% in digital and 10% in film

Question 26

What do we look at to know if image answers our Qs

Answer 26

which tooth/teeth which parts of tooth/teeth what other structures what extent of pathology

Question 27

What do the question answers depend on

Answer 27

type of radiograph taken | clinical justification for it

Question 28

What are diagnostically acceptable poisoning factors for bitewings

Answer 28

show entire crowns of upper and lower teeth include distal aspect of fore standing standing posterior teeth and mesial aspect of last standing tooth may require more than 1 every approximal surface shown at least once without overlap where possible

Question 29

What are diagnostically acceptable poisoning factors for PA

Answer 29

shows entire root shows PA bone shows crown

Question 30

What must radiograph have in addition to correct positioning factors

Answer 30

adequate contrast sharpness resolution as well as minimal distortion

Question 31

What is fault analysis

Answer 31

identifying and explaining fails so can be remedied

Question 32

What are potential faults visible on image

Answer 32

``` too dark or pale inadequate contrast unsharp distorted over collimated receptor marks or damage ```

Question 33

What are potential faults in collimation error

Answer 33

incorrect assembly or receptor holder incorrect alignment between x ray tube and receptor holder incorrect orientation of rectangular collimator (attached to x ray unit)

Question 34

What are potential faults in incorrect image radio density

Answer 34

image too dark or light

Question 35

What are potential causes of incorrect radio density

Answer 35

exposure factors developing factors (FILM) viewing factors

Question 36

What are the exposure factors

Answer 36

incorrect exposure settings, patients tissues too thick, faulty timer on x-ray unit

Question 37

What are developing factors (film)

Answer 37

incorrect duration, incorrect temp, incorrect conc

Question 38

What are viewing factors

Answer 38

inappropriate light source (film), inappropriate display screen (digital) excessive environmental light