Exposure Factors
What are considered the prime exposure factors in radiography?
kVp, mA, exposure time, and SID
What is the primary purpose of filtration in x-ray production?
To remove low-energy x-rays
The relationship between SID and constant IR exposure is described by which principle?
The direct square law
High-frequency generators are preferred because they do what?
Produce a nearly constant kVp and higher output
A 15% increase in kVp is equivalent to what change in mAs?
100% increase (doubling)
Which radiographic parameter directly increases the number of x-ray photons without changing beam energy?
mAs
What does Half Value Layer (HVL) measure?
The thickness of material required to reduce beam intensity by 50%
The inverse square law states radiation intensity varies:
Inversely with the square of the distance
What is the main function of AEC systems?
Terminate exposure at the appropriate receptor dose
If mAs is changed from 20 to 10 due to a smaller patient, the x-ray intensity has:
Halved
Which exposure factor primarily controls the penetrating power of the x-ray beam?
kVp
HVL measurements are most commonly performed using which material?
Aluminum
What is the formula for magnification factor?
MF = SID / SOD
Improper patient positioning when using AEC most likely results in what?
Incorrect receptor exposure
Which two factors, when increased, reduce image receptor exposure?
Distance and filtration
Increasing kVp produces what effect on the x-ray beam?
It increases both the beam energy and IR exposure significantly
If filtration thickness increases, what happens to x-ray beam intensity?
It decreases
Image magnification increases when which factor increases?
OID
A compensating filter creates what type of exposure in body parts of uneven thickness?
Uniform exposure with a nonuniform thickness
If SID changes from 72 inches to 36 inches and the original intensity is 20 mR, what is the new intensity?
80 mR
Increasing mAs causes what change in beam quality and intensity?
No change in quality; increase in intensity
For x-ray tubes operating above 70 kVp, the minimum total filtration required is:
2.5 mm Al
What is the best way to minimize image magnification?
Long SID and short OID
What image characteristic improves when using a small focal spot?
Finer detail of image (Spatial Resolution)
Which technique would give the highest patient dose?
65 kVp/300 mA @ 0.1 sec