X-ray Interactions
Minimizing Patient Exposure
Beam Restriction
Formulas
Take Your Chance
100

What is attenuation?

What is the reduction in # of X-ray photons in the beam, and subsequent loss of energy, as the beam passes through matter. 

100

What is exposure?

What is radiation intensity in air?
100

Scatter production is produced during what interaction?

What is a Compton interaction? 
100

What is the interrelationship of the prime factors?

What is (mas)2(kVp)2/d2

100

What is penumbra?

Penumbra is a geometric unsharpness around the periphery of the image, also known as edge unsharpness?

200

What are the 2 types of coherent scattering and what do they involve?

What is Thomson scattering involving a single electron and Rayleigh scattering involving all of the electrons of the atom? 

200

This is the estimated percentage of radiation exposure the general public receives from diagnostic radiographic examinations?

What is 15%?

200

What are the principal factors that affect the amount of scatter?

What is kilovoltage and irradiated material (the patient)?

200

What is the Compton effect formula?

What is Ei=Es+Eb+Eke

200

What accessory are most collimators equipped with?

What is a positive beam limitation (PBL)?

300

What are the 3 basic rules that govern the possibility of a photoelectric interaction?

1. The incident X-ray energy must be greater than the binding energy of the inner-shell electron

2. A photoelectric interaction is more likely to occur when the X-ray photon energy and the electron binding energy are nearer to one another. 

3. A photoelectric interaction is more likely to occur w/ an electron that is more tightly bound in its orbit. 

300

What are the 3 major types of gonad shielding?

What is flat, shadow, and shaped contact shields?
300

What is the amount of scatter created during an interaction is affected by what factors?

What is volume and the atomic number of the material being irradiated?

300

What is the formula for photoelectric absorption?

What is E1=Eb+Eke?

300

What is ESE?

what is the area where the maximum exposure where the patient receives lies?

400

What is photodisintegration?

What is an interaction between an extremely high-energy photon, above approx. 10 MeV, and the nucleus?

400

What is the effect of grid ratio on patient dose?

What is using an unnecessarily high grid ratio increases patient dose because mAs or kVp must be raised to maintain exposure, while a lower grid ratio helps minimize dose?

400

What does the top shutter of a collimator reduce?

What is reducing the amount of off-focus radiation reaching the IR by absorbing radiation before it exits the tube?
400
What is the approximate ESE formula?
SID=SOD+OID

mR1/mR2=SOD2/SID2

400

Why do electrons farther from the nucleus have greater kinetic energy?

What is because electrons farther from the nucleus are not as tightly bound, requiring less energy to remove from their orbit and therefore possess greater total energy?

500

The probability of a photoelectric interaction increases dramatically as the atomic number rises. What is the mathematical relationship that describes how strongly it increases?

What is approximately proportional to the 3rd power of the atomic number?

500

What is an increase in the number of pulses from a generator?

What is this change in the generator reduces patient ESE by decreasing the proportion of low-energy photons produced by the X-ray tube?

500
What is the added filtration added by the collimator?

What is the use of the collimator that results in added filtration approx. equiv. to 1 mm of al.?

500

What is the mR/mAs for 100 kVp?

What is 5.6?

500

What is the limit set by the FDA for fluoroscopy entrance exposure?

What is 10 cGy/min, or 11.5 R/min?

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