You can make an error if you use the wrong kVp or mA. Remember, on
some radiographic units when you change the mA, the kVp will also change.
BE CERTAIN THE MACHINE FACTORS ARE CORRECT BEFORE MAKING
e. Ensure that timer errors (as allowed by the Bureau of Radiological Health) do
not exceed the following guidelines:
Up to 10 percent.
One "step" between corresponding steps on the step wedge.
4-11. PREVENTIVE MAINTENANCE
Perform the electronic x-ray timing and mAs test routinely at six-month intervals.
Also test following any service work which could affect the calibration of the x-ray
generator timing or the mAs and, of course, if the radiographic equipment is not
4-12. CORRECTIVE MAINTENANCE
If the timing system errors are greater than 10 percent, or if the densities vary
more than one step between the corresponding steps on the wedge, call a qualified
service representative or engineer after you retest the machinery (to ensure you did not
make a mistake in your testing).
Section III. FOCAL SPOT QUALITY CONTROL TEST
The purpose is twofold: the focal spot test determines the approximate focal spot
a. Wisconsin focal spot test tool.
b. One loaded cardboard (10 x 12) film holder.
c. Two small lead sheets.
d. Lead markers.