1. Distance from focal spot of x-ray tube to film ( FFD ) in inches from 26 " to 72" for most applications 30" for portable units and 40" for stationary units

2. Speed of cassette/screen film combination 50, 100, 150, 250, 400, 600, and 800. Normal is 400 or 250

3. Grids May be used to remove scatter radiation from x-ray film. Portable units will use a grid 50% of the time. Stationary units will use a grid all the time except on extremities. There are four types of grid ratios, each require a different exposure technique to penetrate. 

• Grid ratios, 6:1 60% increase in exposure time or mA or mAs or increase 8 kVp

• Grid ratios, 8:1 100% increase in exposure time or mA or mAs or increase 10 kVp

• Grid ratios, 10:1 150% increase in exposure time or mA or mAs or increase 15 kVp

• Grid ratios, 12:1 200% increase in exposure time or mA or mAs or increase 20 kVp

4) Anatomical Region of interest listed for:

• Small Animal: Extremities 2-10cm, Pelvis 7-25cm, Skull 5-15cm, Abdomen 6-25cm,

• Thorax 6-30cm, Chest 6-30cm

• Large Animal: Sizes of anatomical region listed as small, medium, and large: Navicular,

• Fetlock, Knee, Splint bone, Hock, Stifle, Elbow, Shoulder, Chest, Skull, Sinus.

Equipment used;

5) Kilo Voltage ( kVp), Penetrating power produces film contrast. Adjusted for Patient anatomy region and thickness.

• Portable units kV output; 40-80 or 40-90 or 40-100 kVp. in one kVp increments

• Stationary units kVp output; 40-125kVp in one kVp increments

Optimal kVp's based on anatomical region thickness 2-4cm 50kVp, 5-8cm 60 kVp, 9- 11cm 70 kVp, 12-15cm 80 kVp, 16-20cm 90 kVp, 21-30 100 kVp

6) Mill amperes ( mA), Exposure Blacking effect on film. Adjusted to compensate for thickness. 5 mA to 400 mA.

• Portable units mA output; 5, 10, 15, 20, 25, 30, 35, 40 mA output.

• Stationary units mA output; 25, 50, 75, 100, 150, 200, 250, 300, 400 mA output.

7) Time ( T ), Exposure Blacking effect on film. Adjusted for Patient thickness .01 seconds to 5 seconds. Need to have decimals and fractions shown

8) Milliamper seconds, Exposure Blacking effect on film. Same as multiplying mA times

time. Formula mAs = mA- x T mAs can be used in place of mA and exposure time

selections Need to have mAs chart showing different combinations of mA x Time

combinations

9) Output energy High Frequency or non High Frequency output types Portable x-ray

unit High Frequency output produces 100% more or twice as much exposure

Milliroentgen (MR) produces twice the film blackening as a non high frequency unit.

Stationary x-ray unit High Frequency output produces 60% more exposure MR or 60%

more film blackening as a non high frequency unit.

Notes

Double time or mA or mAs will double film blackening

Increase kVp 10 from 50 to 79 kVp will double film blackening

Increase kVp 13 from 80 to 100 kVp will double film blackening

Increase kVp by 2 for each cm patient thickness increase from 50 to 79 kVp

Increase kVp 3 for each cm patient thickness increase from 80 to 100 kVp