Unit 4 - Exposure Technique

What are the primary factors of exposure?

What are the secondary factors of exposure?

Milliamperage (mA)

Exposure time

mAs

mAs controls ....

Reciprocity Law

When a radiograph is too bright or too dark, which exposure factor must be altered?

What are some factors to consider when adjusting your mAs?

You should make a ___% change in mAs to make a visible change in the radiograph

Kilovoltage Peak (kVp)

kVp controls...

TRUE OR FALSE

Before the mAs can be adjusted, the kVp must be enough to penetrate the patient.

Increasing kVp will _______ penetration and _______ absorption. It produces ____-____ contrast with low contrast, and more scatter.

Decreasing kVp will ______ penetration and ______ absorption. It produces ______-_____ contrast with high contrast.

You should make a __% change in kVp to make a visible difference on the radiograph

15% Rule

TRUE OR FALSE

If kVp is too low when you reprocess the image digitally, you may see quantum noise.

TRUE OR FALSE

If kVp was too high during exposure, the image will be reprocessed but the brightness and contrast will not change.

TRUE OR FALSE:

Quantum noise is a result of overexposure.

TRUE OR FALSE:

An image's brightness does not depend on mAs or kVp.

Why does DR use higher kVp and lower mAs?

Focal Spot Size

Increasing focal spot size _____ recorded detail and spatial resolution.
Decreasing focal spot size _____ recorded detail and spatial resolution.

You increase the SID from 30'' to 40'' for an abdomen x-ray.
What will happen to the radiograph?

You decrease the SID from 72'' to 60'' for an AP cart CXR.
What will happen to the radiograph?

TRUE OR FALSE

Any time you change SID with DR, you should also adjust your kVp.

How does the Air-Gap technique reduce scatter?

How should you adjust your technique if you use a grid?

TRUE OR FALSE:

Tube filtration reduces patient dose.

How would you adjust your technique if you used a compensating filter?

How is kVp adjusted with variable kVp-fixed mAs?

How is mAs adjusted with variable mAs - fixed kVp?

Short-Scale Contrast

Long-Scale Contrast

High Subject Contrast

Low Subject Contrast

Which factors will produce good geometric properties on a radiograph?

Which factor will produce sharpness of structural lines on a radiograph?

Which factor will produce adequate visibility of anatomic structures?

A radiograph turns out black and white. The radiographer wants to increase the contrast of the image for the repeat exposure, how will she change her technique?
75 kVp @ 10 mAs

A radiograph turns out with very high contrast. The radiographer wants to see more blacks and whites. How will she change her technique for the repeat exposure?
125 kVp @ 16 mAs

The radiographer is x-raying a 6 month old using the piggostat, but the child is still having a hard time staying still. How will the radiographer adjust the technique?
85 kVp @ 12 mAs

Which formula would we use to figure out the intensity of the beam if the original x-ray beam is 2mR @ 40 SID, and we are changing it to 72 SID?

You took a CXR of a patient before surgery at 125 kVp @ 5 mAs with a 72'' SID
Now you have to do a cart CXR on the same patient after surgery, and you will not get the same SID. Which law will you use to change your technique?

If we wanted to determine the degree of magnification of a radiograph, how would we proceed?

If we want to determine what the object size was of what we x-rayed, how would we proceed?

If we add a grid when using an exam and we have to alter our mAs?

As beam restriction increases (gets tighter), density ______

An image will have higher contrast if the window width is _____