x-ray production

The output phosphor of most modern image intensifiers is comprised of:

zinc cadmium sulfide

An image was produced using 30 milliampere-seconds (mAs) at a 40-inch source-to-image distance (SID). If a new SID of 72 inches is needed, what new mAs value would be needed to maintain image receptor exposure? Equation: (mas1mas2x (d1)2(d2)2)

(30?x (40)2(72)2) = 97.2 mAs

How many heat units are produced on a single-phase machine using 100 milliamperes (mA), .02 second, and 60 kilovolt peak (kVp)?

(rectification constant is 1?) 120 HU

When a 400 miliampere (mA) station is used, which of the following exposure times would be needed to produce 80 milliampere-seconds (mAs)?

0.2 seconds

An image is taken using 10 milliampere-seconds (mAs) with a 5:1 grid. What mAs is needed to maintain receptor exposure when switching to a 16:1 grid?

10/x= 2/6 =30 mAs

An image is taken using 25 milliampere-seconds (mAs) with an 8:1 grid. What mAs is needed to maintain image receptor exposure when switching to a 5:1 grid?

25/x= 4/2 x = 12.5 mAs

Which of the listed x-ray generator types has the least amount of voltage ripple?

3 phase 12 pulse

If all other exposure variables remain constant, which of these object-to-image distances (OID) will produce a radiograph with the highest spatial resolution?

4 inches

This shoulder image was acquired with the following procedural factors: 70 kilovoltage peak (kVp), 120 milliamperes (mA), 0.1 second exposure time, 60-inch source-to-image distance (SID), minimal collimation, and an 8:1 grid. The exposure indicator for this image indicates that the image was underexposed. Which of these modifications would increase image receptor exposure?

40 inch SID

An x-ray of a fractured hip was acquired at a 52-inch source-to-image distance (SID). Using automatic exposure control (AEC), the resulting exposure was 80 milliampere-seconds (mAs). If the exam is repeated at a 40-inch SID, what new mAs will be used by the AEC system?

47.3 mAs

An x-ray was taken using 110 kilovoltage peak (kVp) and 5 milliampere-seconds (mAs) on a high-frequency machine. How many heat units were produced if the rectification constant is 1.40?

770 heat units

Assuming all other technical factors are constant, what field size will produce the lowest image receptor exposure?

8 x 10

A rotating anode has which of these characteristics? (Select all that apply)

A.dissipates heat B. had a larger target than a fixed anode C.is driven by a motor

In what format must images be in so that they can be sent throughout the image viewing system?

DICOM

In this image of a radiographic histogram, what does the y-axis represent?

Frequency of specific exposure values captured by the image receptor

Which of the following scenarios will produce LOW image contrast? (Select all that apply)

High kVp, large field size, 16:1 grid

Each of the images below was acquired with a different set of technical factors. Which image demonstrates an error called quantum mottle?

Image A

When using automatic exposure control (AEC), which of the following may result in an image with excessive image receptor exposure?

Incorrect radiation detector selection

Which of these changes will increase the contrast resolution of a radiographic system?

Increase bit depth

When using an automatic exposure control system (AEC), which of the following would NOT increase the radiation output used during the procedure?

Increased back up timer setting

A more divergent beam can cause which of the following? (Select all that apply)

Increased penumbra, Decreased RE, Increased scatter radiation

Which of these images was acquired using the largest matrix size?

Larger the matrix size, the smaller the pixels, better spatial resolution-Image A

Where does quantization occur during digital image formation

Occurs during image digitization. Is the final step in which the brightness value of each pixel is assigned a number called a gray level

The envelope that surrounds the x-ray tube is most commonly made of:

Pyrex

During a series of mobile chest x-rays, the technologist fails to adjust the kilovoltage peak (kVp) for a hypersthenic patient. This is likely to result in which of the following?

Quantum mottle

A radiograph of the femur is produced using 12 milliampere-seconds (mAs), 70 kilovoltage peak (kVp), 40-inch source-to-image distance (SID), and an 8-inch object-to-image distance (OID). If the image of the femur measures 22 inches, what is the actual length of the femur?

SID - OID = SOD; 40-8=32 SOD/SID= image/actual 17.6 inches

Which of these digital radiography systems is able to display the most diagnostic information?

The higher the byte number, the more information it can display so it might be 12

The degree of subject contrast within the body is controlled by: (Select all that apply)

Tissue thickness, Tissue density, Atomic number

Why are rotating anodes used in x-ray tubes?

To increase tube heat dissipation

The brightness of the image on a viewing monitor is:

a function of the monitor

An off-focus error occurs when the:

a grid is used at the wrong SID

What component of the x-ray tube assembly is the actual source of x-ray photons?

anode target

The source of electrons in a traditional x-ray tube is the:

cathode filament

Which of these changes will improve the spatial resolution recorded in the radiographic image? (Select all that apply)

decreased OID, increased SID, decreased focal spot size; SID and OID

Which of the following will be affected by a change in the actual focal spot size? (Select all that apply)

effective focal spot, spatial resolution, image contrast

Which of the following factors would result in a brighter image being produced at the output phosphor of an image intensifier? (Select all that apply)

flux gain and minification gain

Which of the following is measured by the light field-radiation field alignment test? (Select all that apply)

how well the collimator regulates the field size and whether the area illuminated by the positioning light and area exposed by x rays are the same

An increase in tube potential would increase image receptor exposure by: (Select all that apply)

increasing the number of photons in the beam and increasing the penetrating ability of the beam

A material that does NOT allow the flow of electrons is known as a(n):

insulator

A material that does not allow the flow of electrons is known as a(n):

insulator

A 4-inch OID will produce a radiograph with the highest spatial resolution. To increase the spatial resolution, the object being imaged should be placed as close as possible to the image receptor.

inverse

Processing an anterposterior (AP) lower leg radiograph as an AP abdomen may result in:

it would almost look over saturated and have lower contrast

Which of the following would be caused by increased diagnostic filtration? (Select all that apply)

lower patient dose, lower contrast, decreased exposure to the IR

Which of the following is the appropriate formula to calculate heat units for a 3-phase 12-pulse machine?

mA x time x kVp x 1.41

A step-up transformer should have:

more secondary winding turns than primary winding turns

X-ray photons during fluoroscopy are primarily absorbed by the:

patient

The distance between the detector elements (DELs) measured from center to center is called the:

pixel pitch

A radiograph that has HIGH image contrast will have:

short scale contrast, fewer shades of grey

Which of the following are affected when the source-to-image distance (SID) is changed? (Select all that apply)

size distortion and image receptor exposure, radiographic brightness and spatial resolution

A transformer that has more wire windings on the secondary side than the primary is a/an:

step up transformer

Which of the following statements is/are correct? (Select all that apply

the effective focal spot is smaller and the actual focal spot is larger

Automatic brightness stabilization (ABS) is designed to compensate for changes in:

tissue density

Which of the following will erase the photostimulable phosphor (PSP)?

white light