Unit 1 Attenuation Coefficients

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What is the primary reason radiologic contrast agents are used in imaging?

To reduce the effect of Compton scatter

To decrease the photon energy

To increase the intensity of the x-ray beam

To enhance the differential absorption of certain tissues and organs (correct)

What is the main difference between absorption and attenuation?

Absorption is the effect of x-rays on soft tissue, while attenuation is the effect on bone

Absorption is the scattering of x-rays, while attenuation is the reduction of intensity

Absorption is the reduction of x-ray intensity, while attenuation includes scattering (correct)

Absorption is the effect of x-rays on bone, while attenuation is the effect on soft tissue

What is the significance of atomic number and mass density of tissue on differential absorption?

They decrease the differential absorption of x-rays

They have no effect on differential absorption

They increase the differential absorption of x-rays (correct)

They are only relevant in polychromatic beams

What is the purpose of the midterm and final exams in RADL 3010?

To evaluate student understanding of the first and second half of the course Signup and view all the answers

What is the difference between monochromatic and polychromatic beams in terms of attenuation?

Monochromatic beams have a single energy, while polychromatic beams have a range of energies Signup and view all the answers

What is the probability of PE effect and Compton scatter dependent on?

Photon energy, atomic number, and density Signup and view all the answers

What is the term used to describe the reduction of photons or weakening of the primary beam following penetration through a given thickness?

Attenuation Signup and view all the answers

What occurs when an X-ray or gamma ray beam interacts with atomic particles in matter?

Scattering Signup and view all the answers

What is the energy transferred to the ejected electron in Compton Scattering?

Kinetic energy Signup and view all the answers

What is the mathematical equation for Compton Scattering?

EP = ES + EB + EKE Signup and view all the answers

What is the energy of the Compton scattered photon in the given example?

34.5 kV Signup and view all the answers

What happens to the scattered photon as it travels through matter?

It loses energy Signup and view all the answers

What is the probability of Compton scattering dependent on?

Energy of the incident x-ray Signup and view all the answers

What is the result of Compton scattering in radiography?

Scattered x-rays provide no useful information Signup and view all the answers

What is the term used to describe the energy transferred to the matter as the beam passes through?

Absorption Signup and view all the answers

What type of scattering is described in the passage?

Compton scattering Signup and view all the answers

What is the primary source of occupational radiation exposure received by radiographers?

Compton scattering Signup and view all the answers

What happens to the energy of the x-ray photon in a photoelectric interaction?

It is absorbed by the inner shell electron Signup and view all the answers

What is the energy of the photoelectron ejected from a calcium atom, if the electron binding energy is 4 kV and the incident x-ray energy is 30 kV?

26 kV Signup and view all the answers

What is the relationship between the probability of a photoelectric interaction and the incident x-ray energy?

The probability decreases as the energy increases Signup and view all the answers

What is the relationship between the probability of a photoelectric interaction and the atomic number of the absorbing material?

The probability is directly proportional to the third power of the atomic number Signup and view all the answers

What is the effect of Compton scattering on image contrast?

It decreases image contrast Signup and view all the answers

What happens to the photoelectron ejected from an atom in a photoelectric interaction?

It escapes with kinetic energy Signup and view all the answers

What is the purpose of the binding energy in a photoelectric interaction?

To eject the electron from its orbit Signup and view all the answers

What is the comparison of the probability of a photoelectric interaction between an 80 keV x-ray and fat (Z = 6.3) and barium (Z = 56) compared with soft tissue (Z = 7.4)?

Fat has a lower probability, barium has a higher probability Signup and view all the answers

What is the effect of photoelectric absorption on the final image?

It is not related to the image Signup and view all the answers

What is the result of an x-ray ejecting a K-shell electron from an atom?

An orbital vacancy is created, resulting in an unstable state. Signup and view all the answers

What is the energy of the characteristic x-ray emitted when an outer shell electron drops into the vacancy created by the ejection of a K-shell electron?

The difference between the binding energies of the shells involved. Signup and view all the answers

What happens to the x-rays that undergo photoelectric absorption in the body?

They are completely absorbed by the body. Signup and view all the answers

What is the significance of characteristic x-rays in radiology?

They have no effect on the final radiographic image. Signup and view all the answers

What is the difference between radiopaque and radiolucent structures?

Radiopaque structures absorb x-rays, while radiolucent structures transmit them. Signup and view all the answers

How does the selection of kVp affect the differential absorption of x-rays?

Decreasing kVp increases differential absorption. Signup and view all the answers

What is the relationship between the probability of photoelectric absorption and the atomic number of the tissue?

The probability is proportional to the third power of the atomic number. Signup and view all the answers

How does the energy of the incident x-ray affect the probability of photoelectric absorption and Compton scattering?

Both probabilities decrease with increasing energy. Signup and view all the answers

What is the effect of Compton scattering on image contrast?

Compton scattering decreases image contrast. Signup and view all the answers

What is the result of a compromise between image contrast and patient dose in radiology?

Lower image contrast and higher patient dose. Signup and view all the answers

What is the total mass attenuation coefficient a result of?

Various absorption and scattering processes Signup and view all the answers

What is the symbol that represents the component of total linear attenuation coefficient due to the photoelectric effect?

τ Signup and view all the answers

How does the probability of a photoelectric effect change with the atomic number of the absorbing material?

It is directly proportional to the third power of the atomic number Signup and view all the answers

What is the general trend of the value of μ with increasing energy of the incident beam?

It decreases Signup and view all the answers

Which of the following materials has a higher μ value at a given X-ray energy?

Bone Signup and view all the answers

How does the value of σ/ρ change with increasing X-ray energy?

It decreases Signup and view all the answers

What does the mass density of a tissue affect?

The number of electrons available for interaction Signup and view all the answers

Why do Barium and Iodine compounds have a much higher atomic number and mass density than soft tissue?

Because they have a higher number of electrons and are densely packed Signup and view all the answers

What is the result of dividing the total linear attenuation coefficient by its density?

The mass attenuation coefficient Signup and view all the answers

What is the binding energy of the K shell electron for Barium?

37.4 keV Signup and view all the answers

What happens to the probability of x-ray interaction when the mass density of a tissue is doubled?

It is doubled Signup and view all the answers

Why do x-rays interact more with bone than with soft tissue?

Because bone has a higher mass density Signup and view all the answers

What is the unit of the total linear attenuation coefficient?

m-1 Signup and view all the answers

What is the main difference between the total linear attenuation coefficient and the mass attenuation coefficient?

The total linear attenuation coefficient takes into account density, while the mass attenuation coefficient does not Signup and view all the answers

What happens to Compton scattering as x-ray energy increases?

It decreases slowly Signup and view all the answers

What is the purpose of using contrast agents in radiologic imaging?

To enhance differential absorption in homogeneous tissue Signup and view all the answers

Unit 1 Attenuation Coefficients - Med Rad 2

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Questions and Answers

What is the primary reason radiologic contrast agents are used in imaging?

What is the main difference between absorption and attenuation?

What is the significance of atomic number and mass density of tissue on differential absorption?

What is the purpose of the midterm and final exams in RADL 3010?

What is the difference between monochromatic and polychromatic beams in terms of attenuation?

What is the probability of PE effect and Compton scatter dependent on?

What is the term used to describe the reduction of photons or weakening of the primary beam following penetration through a given thickness?

What occurs when an X-ray or gamma ray beam interacts with atomic particles in matter?

What is the energy transferred to the ejected electron in Compton Scattering?

What is the mathematical equation for Compton Scattering?

What is the energy of the Compton scattered photon in the given example?

What happens to the scattered photon as it travels through matter?

What is the probability of Compton scattering dependent on?

What is the result of Compton scattering in radiography?

What is the term used to describe the energy transferred to the matter as the beam passes through?

What type of scattering is described in the passage?

What is the primary source of occupational radiation exposure received by radiographers?

What happens to the energy of the x-ray photon in a photoelectric interaction?

What is the energy of the photoelectron ejected from a calcium atom, if the electron binding energy is 4 kV and the incident x-ray energy is 30 kV?

What is the relationship between the probability of a photoelectric interaction and the incident x-ray energy?

What is the relationship between the probability of a photoelectric interaction and the atomic number of the absorbing material?

What is the effect of Compton scattering on image contrast?

What happens to the photoelectron ejected from an atom in a photoelectric interaction?

What is the purpose of the binding energy in a photoelectric interaction?

What is the comparison of the probability of a photoelectric interaction between an 80 keV x-ray and fat (Z = 6.3) and barium (Z = 56) compared with soft tissue (Z = 7.4)?

What is the effect of photoelectric absorption on the final image?

What is the result of an x-ray ejecting a K-shell electron from an atom?

What is the energy of the characteristic x-ray emitted when an outer shell electron drops into the vacancy created by the ejection of a K-shell electron?

What happens to the x-rays that undergo photoelectric absorption in the body?

What is the significance of characteristic x-rays in radiology?

What is the difference between radiopaque and radiolucent structures?

How does the selection of kVp affect the differential absorption of x-rays?

What is the relationship between the probability of photoelectric absorption and the atomic number of the tissue?

How does the energy of the incident x-ray affect the probability of photoelectric absorption and Compton scattering?

What is the effect of Compton scattering on image contrast?

What is the result of a compromise between image contrast and patient dose in radiology?

What is the total mass attenuation coefficient a result of?

What is the symbol that represents the component of total linear attenuation coefficient due to the photoelectric effect?

How does the probability of a photoelectric effect change with the atomic number of the absorbing material?

What is the general trend of the value of μ with increasing energy of the incident beam?

Which of the following materials has a higher μ value at a given X-ray energy?

How does the value of σ/ρ change with increasing X-ray energy?

What does the mass density of a tissue affect?

Why do Barium and Iodine compounds have a much higher atomic number and mass density than soft tissue?

What is the result of dividing the total linear attenuation coefficient by its density?

What is the binding energy of the K shell electron for Barium?

What happens to the probability of x-ray interaction when the mass density of a tissue is doubled?

Why do x-rays interact more with bone than with soft tissue?

What is the unit of the total linear attenuation coefficient?

What is the main difference between the total linear attenuation coefficient and the mass attenuation coefficient?

What happens to Compton scattering as x-ray energy increases?

What is the purpose of using contrast agents in radiologic imaging?

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