Chapter 3: Interaction of X-Radiation
Which one of the following is NOT one of the five basic x-ray interactions with matter? A. Bremsstrahlung B. Classical scattering C. Compton scattering D. Photodisintergration E. Photoelectric effect
A. Bremsstrahlung
Which of the following is the x-ray interaction that does NOT cause ionization? A. Classical scattering B. Compton scattering C. Pair production D. Photodisintergration E. Photoelectric effect
A. Classical scattering
Which of the following is the x-ray interaction that does NOT cause ionization? A. Classical scattering B. Compton scattering C. Pair production D. Photodisntegration E. Photoelectric effect
A. Classical scattering
Of the following-radiation interactions with matter, which is most likely to occur at less than 10 keV? A. Coherent scattering B. Compton scattering C. Photoelectric absorption D. Pair production
A. Coherent scattering
A positron is considered a: A. Form of antimatter B. Modified proton C. Form of small-angle scatter D. Byproduct of the photoelectric interaction
A. Form of antimatter
The Compton effect is: A. Independent of Z B. Inversely proportional to Z C. Proportional to E D. Proportional to Z E. Proportional to Z2
A. Independent of Z
The Compton effect is: A. Independent of Z B. Inversely proportional to Z C. Proportional to E D.Proportional to Z
A. Independent of Z
The symbol Zeff indicates: A. Atomic number B. Effective atomic number C. Mass number D. The number of vacancies in an atomic shell
B. Effective atomic number
Compton scattered x-rays: A. Are helpful in diagnostic radiology B. Have lower energy than the incident x-ray C. Improve contrast resolution D. Produce image artifacts
B. Have lower energy than the incident x-ray
Describe backscatter radiation.
Compton-scattered x-rays leave the scattering object in the approximate direction of the incident x-ray beam. Backscatter from the back of the cassette & Bucky can cause an artifact.
Which of the following terms are synonymous? A. Classical scattering and photoelectric absorption B. Compton scattering and photodisintergration C. Photoelectric absorption and Compton scattering D. Characteristic radiation and fluorescent radiation
D. Characteristic radiation and fluorescent radiation
The photoelectric effect is: A. A partially exciting event B. A partially ionizing event C. A radiation-scattering event D. The complete absorption of an electron with the subsequent emission of an x-ray E. The complete absorption of an x-ray with the subsequent emission of an electron
D. The complete absorption of an electron with the subsequent emission of an x-ray
During the Compton effect, MOST of the incident x-ray is given to which of the following? A. Characteristic radiation B. Excitation C. The electron binding energy D. The electron mass E. The scatter x-ray
E. The scatter x-ray
Compton-scattered x-rays:
Have lower energy than the incident x-ray
What controls the quality, or penetration power, of an x-ray beam?
Peak kilovoltage (kVp)
Use of a barium- or iodine- based contrast medium significantly enhances the occurrence of _______ absorption in biologic tissue and results in an increase in the radiation dose to the patient.
Photoelectric
Which interaction of x-radiation with matter is most responsible for the contrast between bone and soft tissue that is seen on an optimal-quality image?
Photoelectric absorption
The radiographic image is principally formed by:
Photoelectric interaction
Describe the photoelectric effect.
The photoelectric effect occurs when an incident x-ray is totally absorbed during the ionization of an tightly bound inner shell electron; incident photon disappears, and the k shell electron now called photoelectron, is ejected from the atom.
The Compton effect is:
The primary source of image noise (fog)
To what does the term FLUORESCENT YIELD refer?
The term FLUORESCENT YIELD refers to the number of x-rays emitted per inner-shell vacancy.
Compton scattering results in _____ scatter.
all-directional
During photoelectric interaction:
an electron is emitted from the atom
To ensure the quality of the radiographic image and the patient's safety, both the radiologist and the radiographer should choose the highest-energy beam that permits adequate radiographic ______ for computed radiography, digital radiography, or conventional radiography.
contrast
For each radiographic procedure, an optimal kVp and mAs combination exists that ______ the dose to the patient while producing an optimal-quality image.
minimizes
During the process of Compton scattering, the energy of the incident x-ray photon is ____ absorbed.
partially
In fluoroscopy, Compton scatter photons can expose imaging _______ who are present in the room.
personnel
Pair production and _______ do not occur within the range of diagnostic radiology.
photodisintergration
The interactions of x-ray photons with biologic matter are ____ ; it is impossible to predict with certainty what will happen to a single photon when it enters human tissue.
random
During the Compton effect, MOST of the x-ray energy is given to
the scatter x-ray
During photoelectric interaction: A. An electron is emitted from an atom B. An x-ray is emitted from an atom C. Electron excitation results D. The atom is made radioactive E. The incident x-ray reappears with reduced energy
A. An electron is emitted from an atom
The photoelectric effect is principally associated with which of the following? A. Absorption of an x-ray B. Bremsstrahlung x-ray production C. Characteristic x-ray production D. Electron excitation E Scattering of an x-ray
A. Absorption of an x-ray
What are the two factors of importance to differential absorption?
1) keV 2) atomic number
Of the five basic mechanisms of x-ray interaction with matter, three are not important to diagnostic radiology. Which are they and why are they not important?
1. Classic scattering 2. Pair production 3. Photo disintegration The x-ray energies involved are outside of the diagnostic imaging range.
What is the effective atomic number of compact bone?
13.8
PET makes use of: A. Annihilation radiation B. Compton scattered photons C. Photoelectrons D. Bremsstrahlung
A. Annihilation radiation
What term is used for the energy absorbed by the patient per unit mass?
Absorbed dose
As a result of photoelectric interactions:
An electron leave the atom
As a result of photoelectric interaction:
An electron leaves the atom
Define the term ATTENUATION:
Attenuation is any process deceasing the intensity of the primary beam that was directed toward a destination.
Which of the following occurs in a Compton interaction? A. An atom is excited B. An atom is ionized C. The secondary electron had kinetic energy equal to the difference between the energy of the incident x-ray and the electron binding energy D. The secondary electron has kinetic energy equal to the incident x-ray
B. An atom is ionized
Which of the following occurs in a Compton interaction? A. An atom is excited B. An atom is ionized C. The secondary electron has kinetic energy equal to the difference between the energy of the incident x-ray and the electron binding energy D. The secondary electron has kinetic energy equal to the incident x-ray E. The secondary photon has wavelength equal to the primary x-ray
B. An atom is ionized
Scatter radiation can result in: 1) A higher-quality diagnostic image 2) Exposure to personnel who are present in a fluoroscopic room during a procedure 3) Radiographic fog on a film image A. 1 and 2 only B. 1 and 3 only C. 2 and 3 only D. 1, 2, and 3
C. 2 and 3 only
Which of the following interactions contributes to image noise? A. Bremsstrahlung B. Classical scattering C. Compton scattering D. Photodisintergration E. Photoelectric effect
C. Compton scattering
Which of the following has the lowest effective atomic number? A. Air B. Bone C. Fat D. Lung E. Muscle
C. Fat
What is the relationship between atomic number (Z) and differential absorption?
It is proportional to mass density, and therefore, so is differential absorption.
After Compton scattering, the scattered x-ray has:
Longer wavelength
