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To produce a radiographic image, photons must go through the tissue and interact with the IR.
The composition of the anatomic tissues affects the x-ray beam interaction.
Differential Absorption is a process whereby some amount of the x-ray beam is absorbed in the tissue, and some passes through the anatomic part.
- Varying anatomic body parts do not absorb the primary beam to the same degree.
- Variations in the absorption and transmission of the exiting x-ray beam structurally represent the anatomic area of interest.
- Creating a radiographic image by differential absorption requires several processes to occur: beam attenuation, absorption, and transmission.
Attenuation is the reduction in the intensity or number of photons in the primary x-ray beam.
- A the x-ray beams passes through anatomic tissue, it loses some of its energy.
- Two distinct processes occur during beam attenuation: absorption and scattering.
  - When higher kVp is used, the overall number of x-ray interactions within matter decrease because of the increased photon transmission.
  - The percentage of photoelectric interactions usually decreases at higher kVp and the percentages of Compton effect interactions is likely to increase at higher kVp
The photoelectric effect is when a photon (bundle of energy) collides with an electron in the K Shell. It has enough energy to eject the electron out of the K-shell out of the atom. The energy is transferred to the emitted electron, called a photoelectron.
- The ability to remove or lose an electron is called ionization.
- Complete absorption of the incoming x-ray photon occurs when it has enough energy to remove an inner shell electron.
- During attenuation of the x-ray beam, the photoelectric effect is responsible for the total absorption of the incoming x-ray photons
- The energy of the incoming x-ray photon must be at least equal to or greater than the binging energy of the inner shell electron.
- After absorption of a portion of the x-ray photons, the overall quantity of the primary beam decreases as it passes through the anatomic part to the IR
- An incoming photon has enough energy to eject an inner shell electron and be completely absorbed . An electron from an upper-level shell fills the electron hole or vacancy. A secondary photon is created by the difference in the electrons binding energies. The probability of the effects depends on the energy of incoming photon and composition of anatomic tissue.
- Fewer photon interactions occur at a higher kVp, but of those interactions, a smaller percentages are photoelectric interactions.
Scattering is the process where some incoming photons are not absorbed but lose energy and change direction during interactions with the atoms comprising the tissue. Scattered and secondary radiations provide no useful information and must be controlled during radiographic imaging.
- Scattering results from the Compton effect. Compton Effect is the loss of energy of the incoming photon occurs when it ejects an outer-shell electron from the tissue atom. The Compton electron or secondary electron is the ejected electron.
  - During attenuation of the x-ray beam, the incoming x-ray photon may lose energy and change direction as a result of the Compton Effect.
  - Compton interactions can occur at any diagnostic x-ray energy and are an important interaction in radiography.
  - The probability of a Compton interaction occurring depends of the energy of the incoming electron, not the atomic number of the anatomic tissue. Compton effects are just as likely to occur in soft tissue as they are in bone.
  - Scattered and secondary radiations provide no useful information and must be controlled during radiographic imaging.
  - An incoming photon loses energy when it ejects an an outer shell electron and changes direction direction.
  - The scattered photons may be absorbed within the patient tissues leave the anatomic part, interact with the IR, or expose anyone near the IR.
  - The probability of this effect depends on the energy of the incoming photon, but not other composition of the anatomic tissue.
  - Fewer photon interactions occur at a higher kVp, but a greater percentage of those interactions are Compton interactions.
Coherent scattering is an interaction that occurs with low energy x-rays, typically below the diagnostic range, also known as classical scattering.
- The x-ray photon does not lose energy and changes direction during coherent scattering.
- If scattered photons strike the IR, it does not contribute any useful information.
- If the scattered photons are absorbed by the patient’s anatomic tissue, it contributes to the radiation exposure of the patient.
- If the scattered photons enter and leave the body, but do not strike the IR, they can contribute to radiation exposure to anyone near the patient.
FACTORS AFFECTING BEAM ATTENUATION
- The amount of x-ray beam attenuation is affected by the thickness of the anatomic part, the atomic number of the atoms contained within it, its tissue density, and the energy of the x-ray beam.
- X-rays are exponentially attenuated and are generally reduced by about 50% for each 4-5 com of tissue thickness.
- Four substances account for most of the beam attenuation in the human body, muscle, fat, bone, and air.
  - Bone attenuates more than muscle, muscles attenuates the x-ray beam more than fat, and fat attenuates the x-ray beam more than air.
- The higher atomic number indicates there are more atomic particles for more interactions with the incoming photons.
  - Tissues that have a higher atomic number, such as bone at 13.8, attenuate the x-ray beam more than tissue that have a lower atomic number, like fat at 6.3.
- Tissue density,or the compactness of atomic particles composing the anatomic part, also affects the amount of beam attenuation.
  - Muscle (effective atomic number 7.4) and fat (effective atomic number 6.3) tissue are similar in effective atomic number; however, their atomic particles differ in compactness, and their tissue densities varies
  - Muscles tissue has atomic particles that are more densely packed or compact and therefore attenuate the x-ray beam more than fat cells.
  - Bone is composed of tissue with a higher atomic number, and the atomic particles are more compacted or densely packed
- Higher penetrating x-rays (shorter wavelength with higher frequencies) are more likely to be transmitted through anatomic tissue without interacting with the tissues' atomic structures.
- Lower-penetrating x-rays (longer wavelengths with lower frequency) are more likely to interact with the tissues' atomic structures.
Transmission- If any incoming x-ray photon passes through the anatomic part with any interactions with the atomic structures
Exit Radiation - also known as remnant radiation, is composed

New Note

To produce a radiographic image, photons must go through the tissue and interact with the IR.
The composition of the anatomic tissues affects the x-ray beam interaction.
Differential Absorption is a process whereby some amount of the x-ray beam is absorbed in the tissue, and some passes through the anatomic part.
- Varying anatomic body parts do not absorb the primary beam to the same degree.
- Variations in the absorption and transmission of the exiting x-ray beam structurally represent the anatomic area of interest.
- Creating a radiographic image by differential absorption requires several processes to occur: beam attenuation, absorption, and transmission.
Attenuation is the reduction in the intensity or number of photons in the primary x-ray beam.
- A the x-ray beams passes through anatomic tissue, it loses some of its energy.
- Two distinct processes occur during beam attenuation: absorption and scattering.
  - When higher kVp is used, the overall number of x-ray interactions within matter decrease because of the increased photon transmission.
  - The percentage of photoelectric interactions usually decreases at higher kVp and the percentages of Compton effect interactions is likely to increase at higher kVp
The photoelectric effect is when a photon (bundle of energy) collides with an electron in the K Shell. It has enough energy to eject the electron out of the K-shell out of the atom. The energy is transferred to the emitted electron, called a photoelectron.
- The ability to remove or lose an electron is called ionization.
- Complete absorption of the incoming x-ray photon occurs when it has enough energy to remove an inner shell electron.
- During attenuation of the x-ray beam, the photoelectric effect is responsible for the total absorption of the incoming x-ray photons
- The energy of the incoming x-ray photon must be at least equal to or greater than the binging energy of the inner shell electron.
- After absorption of a portion of the x-ray photons, the overall quantity of the primary beam decreases as it passes through the anatomic part to the IR
- An incoming photon has enough energy to eject an inner shell electron and be completely absorbed . An electron from an upper-level shell fills the electron hole or vacancy. A secondary photon is created by the difference in the electrons binding energies. The probability of the effects depends on the energy of incoming photon and composition of anatomic tissue.
- Fewer photon interactions occur at a higher kVp, but of those interactions, a smaller percentages are photoelectric interactions.
Scattering is the process where some incoming photons are not absorbed but lose energy and change direction during interactions with the atoms comprising the tissue. Scattered and secondary radiations provide no useful information and must be controlled during radiographic imaging.
- Scattering results from the Compton effect. Compton Effect is the loss of energy of the incoming photon occurs when it ejects an outer-shell electron from the tissue atom. The Compton electron or secondary electron is the ejected electron.
  - During attenuation of the x-ray beam, the incoming x-ray photon may lose energy and change direction as a result of the Compton Effect.
  - Compton interactions can occur at any diagnostic x-ray energy and are an important interaction in radiography.
  - The probability of a Compton interaction occurring depends of the energy of the incoming electron, not the atomic number of the anatomic tissue. Compton effects are just as likely to occur in soft tissue as they are in bone.
  - Scattered and secondary radiations provide no useful information and must be controlled during radiographic imaging.
  - An incoming photon loses energy when it ejects an an outer shell electron and changes direction direction.
  - The scattered photons may be absorbed within the patient tissues leave the anatomic part, interact with the IR, or expose anyone near the IR.
  - The probability of this effect depends on the energy of the incoming photon, but not other composition of the anatomic tissue.
  - Fewer photon interactions occur at a higher kVp, but a greater percentage of those interactions are Compton interactions.
Coherent scattering is an interaction that occurs with low energy x-rays, typically below the diagnostic range, also known as classical scattering.
- The x-ray photon does not lose energy and changes direction during coherent scattering.
- If scattered photons strike the IR, it does not contribute any useful information.
- If the scattered photons are absorbed by the patient’s anatomic tissue, it contributes to the radiation exposure of the patient.
- If the scattered photons enter and leave the body, but do not strike the IR, they can contribute to radiation exposure to anyone near the patient.
FACTORS AFFECTING BEAM ATTENUATION
- The amount of x-ray beam attenuation is affected by the thickness of the anatomic part, the atomic number of the atoms contained within it, its tissue density, and the energy of the x-ray beam.
- X-rays are exponentially attenuated and are generally reduced by about 50% for each 4-5 com of tissue thickness.
- Four substances account for most of the beam attenuation in the human body, muscle, fat, bone, and air.
  - Bone attenuates more than muscle, muscles attenuates the x-ray beam more than fat, and fat attenuates the x-ray beam more than air.
- The higher atomic number indicates there are more atomic particles for more interactions with the incoming photons.
  - Tissues that have a higher atomic number, such as bone at 13.8, attenuate the x-ray beam more than tissue that have a lower atomic number, like fat at 6.3.
- Tissue density,or the compactness of atomic particles composing the anatomic part, also affects the amount of beam attenuation.
  - Muscle (effective atomic number 7.4) and fat (effective atomic number 6.3) tissue are similar in effective atomic number; however, their atomic particles differ in compactness, and their tissue densities varies
  - Muscles tissue has atomic particles that are more densely packed or compact and therefore attenuate the x-ray beam more than fat cells.
  - Bone is composed of tissue with a higher atomic number, and the atomic particles are more compacted or densely packed
- Higher penetrating x-rays (shorter wavelength with higher frequencies) are more likely to be transmitted through anatomic tissue without interacting with the tissues' atomic structures.
- Lower-penetrating x-rays (longer wavelengths with lower frequency) are more likely to interact with the tissues' atomic structures.
Transmission- If any incoming x-ray photon passes through the anatomic part with any interactions with the atomic structures
Exit Radiation - also known as remnant radiation, is composed