radiology image formation & quality

Question 1

In conventional film, which chemical is present in the emulsion?

Answer 1

Silver Halide (makes the film turn black)

Question 2

What is the advantage of having a double emulsion in radiographic film?

Answer 2

It increases the sensitivity and reduces the dose required.

Question 3

What are 2 examples of rare earth phosphors used to make radiographic screens?

Answer 3

1. Gadolinium
2. Lanthanum

Question 4

What are the 3 things screen speed depends on?

Answer 4

1. Thickness of the phosphor layer.
2. Crystal size (larger crystals indicate faster film)
3. Conversion efficiency.

Question 5

What is latent image formation?

Answer 5

Unable to see with the naked eye.

Question 6

State the 5 steps of processing.

Answer 6

1. Development
2. Intermediate Washing
3. Fixing
4. Final Washing
5. Drying

2x wash stages

Question 7

What occurs during the development aspect of processing?

Answer 7

The silver halide molecules present in the emulsion turn into silver.

Question 8

What do the black areas on an X-ray indicate.

Answer 8

Areas where there are no silver deposits.

Question 9

What is the purpose of intermediate washing phases?

Answer 9

Stops the developing process by washing off the developer.

Question 10

What might occur if the developer was left on the film for too long?

Answer 10

The whole emulsion would be converted.

Question 11

What occurs in the fixing stage?

Answer 11

Removes any unreacted silver halide crystals.

(without this, the image would turn foggy)

Question 12

What is the purpose of the final washing stage?

Answer 12

To remove the fixer.

Question 13

What would happen to the film if the fixer wasn’t removed?

Answer 13

The film would go brown as it reacts with silver, producing SILVER SULPHIDE.

Question 14

What does the drying phase of processing do to the film?

Answer 14

Hardens the emulsion.

Question 15

What are the 3 main film faults?

Answer 15

1. overexposure
2. overdevelopment (increased time, temp and concentration)
3. fogging

Question 16

Why might a film be pale?

Answer 16

1. Under-exposure.
2. Under-development.
3. Film back to front.

Question 17

Why may a film be opaque?

Answer 17

• Due to inadequate fixation/exhaused fixer solution.
• Leaves unreacted Silver Bromide crystals on the film.

Question 18

What may cause a brown film?

Answer 18

Inadequate final washing leading to the formation of silver sulphide.

Question 19

What could cause double imaging on a phosphor plate?

Answer 19

Where the previous image hasn’t been wiped off before use.

Question 20

How are phosphor plates wiped of pervious images?

Answer 20

White light is put on top.

Question 21

What are the 6 aims of quality assurance programmes?

Answer 21

1. Consistently high standard.
2. Reduce repeats.
3. Determine errors.
4. Increase efficiency.
5. Reduce costs.
6. Reduce dose.

Question 22

How is image quality of radiographs assessed?

Answer 22

Previous grading of 1-3 (excellent, diagnostically acceptable and unacceptable).

*Nowadays, just acceptable and unacceptable is used. findings recorded in the image quality log)

Question 23

What is the coin test in radiology quality assurance?

Answer 23

• Tests the light-tightness and safelight in a darkroom.
• Involves withdrawing an opaque cover at 30 second intervals.

Question 24

How often should a radiology audit be completed by someone within the practice other than the person responsible for QA?

Answer 24

Once every year.

Question 25

How often should a radiology QA audit be carried out by someone external to the practice?

Answer 25

1 audit every 3 years.