KETTERING FINAL EXAM ACTUAL QUESTIONS AND
SOLUTIONS RATED A+
✔✔Quality - ✔✔(kVp; energy and penetrability)
Influenced by:
increase kVp results in an increase in X-ray quality and an increase in penetrability
an increase in filtration results in an increase x-ray quality, although the peak energy
has not changed
✔✔Quantity - ✔✔(mAs; rate, intensity, pt dose)
Influenced by:
X-ray quantity directly proportional to mAs
I1/I2 = mAs1/mAs2 (no squaring)
Ex. 70 kVp, 10 mAs, pt dose of 18 C/kg; New exposure 25 mAs, what is new intensity?
18/x = 10/25 = x= 450/50 = 45 C/kg
✔✔Filtration - ✔✔(increases quality; decreases quantity)
Measured in half-value layer= thickness of an absorbing material required to reduce the
x-ray intensity by one-half of its original value
The only technical factors that effect HVL are kVp and filtration
✔✔Inverse Square Law - ✔✔X-ray quantity (intensity) is inversely proportional to the
square of the distance from the radiation source
Used to calculate a change in beam intensity with changes in SID
I1/I2 = [SID2/SID1] ^2
✔✔Direct Square Law - ✔✔(density maintenance or exposure maintenance)
Used to maintain radiographic density with changes in SID
mAs1/mAs = [SID1/SID2]^2 (NONO)
✔✔Primary radiation - ✔✔useful radiation and consists of x-ray photons directed
through x-ray tube's window port in a direction toward patient
X-ray beam before it hits patient
-Photons are incident photons
✔✔Secondary Radiation - ✔✔Radiation that is emitted from atoms of matter after an x-
ray photon from the primary beam interacts with matter (characteristic radiation)
✔✔Remnant Radiation - ✔✔Exit radiation
portion of attenuated x-ray beam that emerges from the patient and interacts with the
IR.
Remnant x-ray beam is also known as image forming beam
✔✔Attenuation - ✔✔progressive absorption of x-ray beam as it passes through matter
, ✔✔What are some properties of x-rays? - ✔✔Packets of energy that travels in
waveform
Highly penetrating and invisible
Heterogeneous and polyenergetic= have a wide variety of wavelengths and energies
Travel in straight lines
Can ionize matter and release small amounts of energy upon passing through matter
Can produce chemical and biological effects
Produces secondary and scattered radiation
Travel at the speed of light
Cause flourescence of certain crystals (intensifying screens)
Cannot be focused by a lens and cannot be reflected or refracted
Affect phtographic emulsion
Contains no mass or electrical charge
High frequencies and very short wavelengths
✔✔Compton effect (scatter) - ✔✔Partial absorption of incident xray photons
Incident x-ray photon interacts with an outer shell electron of a target atom and removes
the electron
-Interactions can be forward scattering, resulting in a degradation of image contrast;
side scatter, resulting in occupational exposure; or backscatter, resulting in patient
exposure
OUTERMOST SHELL
✔✔Biggest source of scatter? - ✔✔Patient
✔✔What angle receives least amount of scatter radiation? - ✔✔90 degree angle; right
angle; or perpendicular to source
✔✔What is the max number of times that an x-ray can be scattered before it loses all of
its energy? - ✔✔twice
✔✔Every time an x-ray photon gets scattered how much will it contain of its original
intensity? - ✔✔1/1000th
✔✔What is the brief interaction of compton effect? - ✔✔1 Incoming-> 2 leaving "straight
out of compton"
(recoil e- and scattered) (scattered photon always has a longer wavelength [60-90])
✔✔Photoelectric Effect - ✔✔Total absorption of the x-ray photon
Incident x-ray photon interacts with an inner (K) shell electron of a target atom and
removes the electron
All of the remaining energy of the incident photon is transferred to the ejected electron
(photoelectron) (post-absorption)
Photoelectric interaction is the PRIMARY SOURCE OF PATIENT DOSE
INNER SHELL
SOLUTIONS RATED A+
✔✔Quality - ✔✔(kVp; energy and penetrability)
Influenced by:
increase kVp results in an increase in X-ray quality and an increase in penetrability
an increase in filtration results in an increase x-ray quality, although the peak energy
has not changed
✔✔Quantity - ✔✔(mAs; rate, intensity, pt dose)
Influenced by:
X-ray quantity directly proportional to mAs
I1/I2 = mAs1/mAs2 (no squaring)
Ex. 70 kVp, 10 mAs, pt dose of 18 C/kg; New exposure 25 mAs, what is new intensity?
18/x = 10/25 = x= 450/50 = 45 C/kg
✔✔Filtration - ✔✔(increases quality; decreases quantity)
Measured in half-value layer= thickness of an absorbing material required to reduce the
x-ray intensity by one-half of its original value
The only technical factors that effect HVL are kVp and filtration
✔✔Inverse Square Law - ✔✔X-ray quantity (intensity) is inversely proportional to the
square of the distance from the radiation source
Used to calculate a change in beam intensity with changes in SID
I1/I2 = [SID2/SID1] ^2
✔✔Direct Square Law - ✔✔(density maintenance or exposure maintenance)
Used to maintain radiographic density with changes in SID
mAs1/mAs = [SID1/SID2]^2 (NONO)
✔✔Primary radiation - ✔✔useful radiation and consists of x-ray photons directed
through x-ray tube's window port in a direction toward patient
X-ray beam before it hits patient
-Photons are incident photons
✔✔Secondary Radiation - ✔✔Radiation that is emitted from atoms of matter after an x-
ray photon from the primary beam interacts with matter (characteristic radiation)
✔✔Remnant Radiation - ✔✔Exit radiation
portion of attenuated x-ray beam that emerges from the patient and interacts with the
IR.
Remnant x-ray beam is also known as image forming beam
✔✔Attenuation - ✔✔progressive absorption of x-ray beam as it passes through matter
, ✔✔What are some properties of x-rays? - ✔✔Packets of energy that travels in
waveform
Highly penetrating and invisible
Heterogeneous and polyenergetic= have a wide variety of wavelengths and energies
Travel in straight lines
Can ionize matter and release small amounts of energy upon passing through matter
Can produce chemical and biological effects
Produces secondary and scattered radiation
Travel at the speed of light
Cause flourescence of certain crystals (intensifying screens)
Cannot be focused by a lens and cannot be reflected or refracted
Affect phtographic emulsion
Contains no mass or electrical charge
High frequencies and very short wavelengths
✔✔Compton effect (scatter) - ✔✔Partial absorption of incident xray photons
Incident x-ray photon interacts with an outer shell electron of a target atom and removes
the electron
-Interactions can be forward scattering, resulting in a degradation of image contrast;
side scatter, resulting in occupational exposure; or backscatter, resulting in patient
exposure
OUTERMOST SHELL
✔✔Biggest source of scatter? - ✔✔Patient
✔✔What angle receives least amount of scatter radiation? - ✔✔90 degree angle; right
angle; or perpendicular to source
✔✔What is the max number of times that an x-ray can be scattered before it loses all of
its energy? - ✔✔twice
✔✔Every time an x-ray photon gets scattered how much will it contain of its original
intensity? - ✔✔1/1000th
✔✔What is the brief interaction of compton effect? - ✔✔1 Incoming-> 2 leaving "straight
out of compton"
(recoil e- and scattered) (scattered photon always has a longer wavelength [60-90])
✔✔Photoelectric Effect - ✔✔Total absorption of the x-ray photon
Incident x-ray photon interacts with an inner (K) shell electron of a target atom and
removes the electron
All of the remaining energy of the incident photon is transferred to the ejected electron
(photoelectron) (post-absorption)
Photoelectric interaction is the PRIMARY SOURCE OF PATIENT DOSE
INNER SHELL
