Exposure Factors

Question 1

mA

Answer 1

Milliamperage, or mA, is a measure of the quantity of current passing throughthex-raytubeatthetimeoftheexposure.It is thedetermining factorfordensity. (mA determineshowmanyx-raysareproducedbycontrollinghowhotthefilament gets).

Question 2

Exposure Time (in seconds)

Answer 2

The exposure time determines how long the mA will be working. Time can be stated in fractions, decimals, or milliseconds (ms). Time also controls the quantity of x-rays produced because the time determines how long the mA will be working.

Question 3

mAs-

Answer 3

mA multiplied by time forms a unit called the mAs, or milliampere-seconds.

Question 4

Kilovoltage-peak (kVp)

Answer 4

kVp is the factor that determines the energy of the x-ray photons produced because it determines the amount of kinetic energy each electron has as it moves from the filament to the anode. Affects quality of the beam. Kilovoltage (kVp) is the main controlling factor for radiographic contrast. This factor must be set on the control panel by the radiographer before every x-ray exposure.

Question 5

Distance (SID)

Answer 5

intensity of beam increases with shorter distances and decreases with longer distances.

Question 6

Cassette Size

Answer 6

The most common image receptor cassettes are 14x17 (35x43cm), 11x14 (30x35cm), 10x12 (24x30cm), & 8x10. The cassette size selected for specific examinations should be chosen so that they are large enough to demonstrate the anatomy of interest completely with reasonable margin for error, laterality marker inclusion and collimation.

Films can be placed lengthwise (LW) or crosswise (CW) depending on how many projections will be included on a single cassette and the specific anatomy to be demonstrated.

Question 7

English-Metric Conversion for film sizes:

Answer 7

1 inch– 2.54cm

l cm: 0.3937inches

40inch SID = approx. 1 meter