Equipment QC - percentages

A QC test shows that the central ray does not align with the indicated center of the radiation field. What tolerance should the alignment remain within?

Central-ray alignment should be within ±1% of the SID.

At a 100-cm SID, what is the maximum acceptable central-ray alignment error?

1 cm, because 1% of 100 cm = 1 cm.

Which QC test determines whether the visible light field accurately represents the actual x-ray exposure field?

Light field–radiation field coincidence testing.

How closely should the light field correspond to the actual radiation field?

Within ±2% of the SID.

At a 100-cm SID, what is the maximum acceptable light field–radiation field difference?

2 cm, because 2% of 100 cm = 2 cm.

A radiographic unit displays an SID of 100 cm. How closely should the actual SID agree with the indicated SID?

Within ±2% of the indicated SID.

What QC test compares the actual exposure time with the exposure time selected at the control panel?

Exposure timer accuracy.

How closely should the actual exposure time agree with the indicated exposure time?

Within ±5%.

A technologist selects 80 kVp. According to the current Clover QC material, how closely should the actual kVp agree with the selected kVp?

Within ±5%.

Three exposures are made using identical kVp, mA, exposure time, SID, and setup. Which QC characteristic is being evaluated?

Exposure reproducibility.

What does exposure reproducibility evaluate?

Whether repeated exposures made with identical technical factors produce essentially the same radiation output.

According to the current Clover material, how much variation is allowed for exposure reproducibility?

±5%.

Exposure output per mAs is compared between different mA stations. Which QC test is being performed?

Exposure linearity.

What does exposure linearity evaluate?

Whether different mA stations produce proportional radiation output for the same mAs.

According to the current Clover material, exposure per mAs should not differ by more than what amount between mA stations?

10%.

What is the easiest way to distinguish reproducibility from linearity?

Reproducibility = SAME settings repeated; linearity = DIFFERENT mA stations compared.

What QC tolerance pattern should be memorized for CR alignment, field coincidence, SID indicator, timer, kVp, reproducibility, and linearity?

1% – 2% – 2% – 5% – 5% – 5% – 10%.