Lab Final Exam Review

Question 1

Used to test the accuracy of the kvp settings

Answer 1

Wisconsin test cassette

Question 2

Used to measure radiation output for mA reciprocity, linearity and reproducibility tests

Answer 2

R-meter

Question 3

Used to measure the luminance and ambient light output of computer work station monitors as well as radiologists high resolution monitors used for diagnosis

Answer 3

Photometer

Question 4

Used to determine accuracy of collimation shutters when adjusting light field size

Answer 4

Collimater test tool

Question 5

Used to determine if primary beam is perpendicular from source to image receptor

Answer 5

Beam alignment test tool (penny test)

Question 6

Used to check the timer of a 3 phase unit

Answer 6

Motorized synchronous spinning top test tool

Question 7

What is the formula for the synchronous/electric timer test formula?

Answer 7

360 degrees x Time = degree of arc

Question 8

What is the variable in the mA reciprocity test?

Answer 8

mA/time is varied to make exposures that will produce the same mAs or quantities of radiation.

Question 9

How is the mA reciprocity test conducted?

Answer 9

Using an R-meter to measure radiation output. Must be within +or- 10% of each R-meter reading

Question 10

What does reciprocity allow?

Answer 10

Allows the technologist to vary the mA and time to reduce patient motion or use a breathing technique while still using the same mAs.

Question 11

What is the CR reproducibility test used for?

Answer 11

1. To determine if the same technique will produce a constant radiation output or intensity from one exposure to another.
2. To test the calibration of a CR reader.

Question 12

How is the CR reproducibility test conducted when testing the calibration of a CR reader?

Answer 12

Making 4 exposures using the same KV, mA and time. All 4 images should display the same EI values after being processed in the same CR reader.

Question 13

What is the percentage of allowance in the reproducibility test?

Answer 13

+or- 5% of each R-meter reading.

Same technique = constant radiation output

Question 14

What does linearity refer to?

Answer 14

The proportionate accuracy of the radiation output of one mA station in relation to another (typically doubling), but using the same time. Must be within +or- 10% of each R-Meter reading

Question 15

What can the linearity test he used for?

Answer 15

To test the calibration of a CR reader by making 3 exposures using the same time and doubling the mA, which will double the mAs and radiation output. EI values will increase or decrease proportionately.

Question 16

Describe the relationships for Konica and Agfa exposure values:

Answer 16

Konica inversely related- double mAs and S number will decrease by half

Agfa directly related- Double mAs and LGM value will increase by 0.3

Question 17

What is the allowable percentage of error in the collimator test?

Answer 17

\+or- 2% of SID. 
Approximately 2cm (size of penny)

Question 18

How much can the KV vary during an exposure? What tool is used to compare exposure densities to determine the correct kvp exposure?

Answer 18

+or- 4 kvp from actual kvp.

Densitometer is used

Question 19

Explain the dark noise test:

Answer 19

Done on an unexposed and erased plate to asses the level of intrinsic noise present in the CR reader system

Question 20

How should images look after dark noise and uniformity tests?

Answer 20

Uniform without the presence of any noise or artifacts

Question 21

What does the AAPM TG 18 test pattern determine?

Answer 21

Spatial resolution, luminance, display noise, and reflection.

Digital display QC test that tests the spatial resolution and quality of the image displayed on the monitor.

Question 22

What is the half value layer?

Answer 22

The amount of material needed to reduce X-ray beam intensity by half.

• most commonly aluminum
• above 70kvp=2.5 mm AL recommended

Question 23

What factors does quality control tests test?

Answer 23

Density
Patient dose
Contrast
Repeat rates