Regarding subject contrast in radiography, which of the following are correct?

It depends on the thickness of the structure being imaged

It depends on the linear attenuation coefficients of the structures being imaged

It increases with the tube kV

Contrast between low-atomic-number structures (e.g. fat and muscle) is strongly affected by changes in the tube kV

Contrast between air and soft tissue is due to differences in their atomic numbers

Concerning radiographic contrast:

Attenuation of the X-ray beam depends upon the degree of Bremsstrahlung in the tissue

Most structures on a chest radiograph exhibit good radiographic contrast

In principle, contrast media have the same effect on demonstrating contrast between tissues as increasing the peak kV (kVp)

All contrast media attenuate X-rays to a higher degree than the tissue

Positive-contrast media should generally have high atomic numbers to maximize the degree of photoelectric absorption

Which of the following are correct for positive-contrast media?

They should ideally have an absorption edge just to the left of the major part of the beam spectrum

Barium has a K-absorption edge of approximately 23 keV

Iodine has a lower atomic number than barium

Iodine most effectively attenuates photons with energies close to 37 keV

They may produce characteristic radiation

Concerning magnification:

It occurs because X-rays converge on the object

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