Radiographic Quality

Question 1

Radiographic Quality Requires:

Answer 1

Balanced Contrast and Density AND

Correct Anatomy Placement

Question 2

Density

Answer 2

Overall blackening of the film

Controlled by mAs

Question 3

Contrast

Answer 3

The difference between adjacent densities on a radiograph OR varying shades of gray on film
Controlled by kVp

Question 4

Other Factors Influencing Radiographic Quality:

Answer 4

amount and or type of tissue, collimation, filtration and grids, processing

Question 5

Image Assessment: A questions and answer process to determine if the radiographic image is:

Answer 5

Acceptable and Optimal
Acceptable but Suboptimal
Unacceptable and Must be repeated

Question 6

Image Assessment Questions:

Answer 6

ANATOMY

1) Is the required anatomy on the film?
2) Is the required anatomy properly displayed on the film?

If not, what needs to be repositioned and/or realigned (part, film, cr)

LIGHT
1) Is the image too light?
2) If yes, are bone details visible? Yes - increase mAs
N0 - increase kVp

DARK
1) Is image too dark?
2) If yes, are bone details visible?
Yes - decrease mAs
No - decrease kVp

Question 7

Rule of Thumb: If you can see the bone…

Answer 7

leave the kVp alone

Question 8

Other questions to consider

Answer 8

Was the SID correct?
Is collimation correct?
Are processor solution strengths and temps correct?

Question 9

mAs

Answer 9

quantity of X-rays (mA x s = mAs)

It is responsible for the density on a radiograph

Question 10

Radiographic Density

Answer 10

the films overall darkness

Question 11

mA and mAs

Answer 11

there is a direct relationship between mA and mAs

Double the mA = double the mAs
100mA x .2(s) = 20 mAs
200mA x .2(s) = 40mAs

1/2 the mA = 1/2 mAs
100mA x .2(s) = 20mAs
50mA x .2(s) = 10mAs

TIME DOESN’T CHANGE

Question 12

Time (s) & mAs

There is a direct relationship between time (s) and mAs

Answer 12

Double the time (s) = double the mAs
100mA x .2(s) = 20mAs
100mA x .4(s) = 40mAs

1/2 the time (s) = 1/2 the mAs
100mA x .2(s) = 20mAs
100mA x .1(s) = 10mAs

mA doesn’t change

Question 13

50% mAs Reciprocal Rule

Answer 13

doubling or halving the mAs will double or half FILM DENSITY

Example:
20mAs 76 kVp
1/2 or 10mAs - decreases density
2x or 40mAs - increases density

Question 14

15% kVp Rule

Answer 14

Adding or subtracting 15% kVp (aprox 10) has the same effect on FILM DENSITY as doubling or halving the mAs

Remember: proper contrast is dependent upon adequate FILM DENSITY

Example:
20mAs 76 kVp
decrease 15% to 65 kVp - lighter
increase 15% to 87 kVp - darker

Question 15

Example of these rules:

Answer 15

decreasing kVp by 15%
looks the same as
decreasing mAs by 50%

increasing kVp by 15%
looks the same as
increasing mAs by 100%

Question 16

The Technique Rule is applied for changes in SIDis the density maintenance or direct proportion rule

Answer 16

If SID is changed:
mAs is adjusted to maintain DENSITY
Use 3x the 40” mAs if SID increases to 72”
Use 1/3 the 72” mAs at 40”

Question 17

FFD/SID Film Density Example

Answer 17

Example 1
40” SID, 25 mAs, 75 kVp
Optimal Density

Example 2
72” SID, 25 mAs, 75 kVp

Increased SID = Decreased Density

Question 18

Grids & Film Density

Answer 18

Non Grid (table top)
Grid (bucky)