Chapter three Flashcards
When a technical exposure factor of 100 kVp is selected, which of the following occurs?
A. The electrons will be accelerated from the anode to the cathode with an average energy of 33 keV.
B. The electrons will be accelerated from the cathode to the anode with an average energy of 33 keV.
C. The beam will contain all photons having energy of 100 keV.
D. The beam will contain photons having energies of 100 keV or less, with an average energy of about 33 keV.
D. The beam will contain photons having energies of 100 keV or less, with an average energy of about 22 keV.
The passage of X-ray photons through a patient without interaction in body tissue is called:
Direct transmission
In which of the following X-ray interactions with matter is the energy of the incident photon completely absorbed?\ Compton Photoelectric Incoherent Rayleigh
Photoelectric
What is the result of coherent scattering?
Usually just a small angle change in the direction of the incident photon.
A technical exposure factor of 100 kVp means that the electrons bombarding the anode of the X-ray tube have a maximum energy of:
100 kVp or 100,000 eV
A Compton scattered electron:
is absorbed within a few microns of the site of the original Compton interaction.
Most scattered radiation produced during radiographic procedures is the direct result of which of the following? Photoelectric absorption Nuclear decay Image-formation electrons Compton interactions
Compton interactions
A reduction in the number of primary photons in the X-ray beam through absorption and scatter as the beam passes through the patient in its path defines:
Attenuation
Before interacting with matter, an incoming X-ray photon may be referred to as which of the following? Attenuated photon Primary photon Ionized photon Scattered photon
Primary photon
Within the energy range of diagnostic radiology (23 to 150 kVp), which includes mammography, when kVp is decreased, the patient dose:
increases
Which of the following statements best describes mass density?
It is the # of electrons per gram of tissue.
It is the same as radiographic density.
It relates the way the effective atomic number of biologic tissues influences absorption.
It is measured in grams per cubic centimeter.
It is measured in grams per cubic centimeter.
Of the following interactions between x-radiation and matter, which does not occur in the range of diagnostic radiology?
Photoelectric absorption.
Pair production
Photodisintegration
Pair production and Photodisintegration
The quality, or penetrating power, of an X-ray beam is controlled by:
kVp
Small angle scatter:
Degrades the appearance of a completed radiographic image by blurring the sharp outlines of dense structures.
For a diagnostic radiologic examination, the selection of technical exposure factors using an optimal kVp and mAs combination:
Produces an xray image of acceptable quality while minimizing patient dose.
Within the energy range of diagnostic radiology, as absorption of electromagnetic energy in biologic tissue increases, the potential for biologic damage:
Increases
Which of the following terms are synonymous?
Coherent scattering
Classical scattering
Unmodified scattering
Coherent, Classical and Unmodified
Noninteracting and small-angle scattered photons comprise:
exit, or image formation, radiation
Direct transmission means that X-ray photons:
Pass through biologic tissue without interaction.
Which of the following has the same mass and magnitude of charge as a negatron? Deuteron Neutron Positron Proton
Positron
Which of the following interactions between x-radiation and matter does not occur within the range of diagnostic radiology? Coherent scattering Compton scattering Photoelectric absorption Pair production
Pair production
kVp controls:
quality, or penetrating power, of the X-ray photons in the beam.
Primary radiation is synonymous with:
direct radiation
Which of the following are radiographic image receptors? Radiographic grid Digital radiography receptor Phosphor plate Radiographic film
Digital radiography receptor, phosphor plate, radiographic film.
The process most responsible for the contrast between bone and soft tissue in a diagnostic radiographic image is:
Photoelectric absorption.
T/F? The radiographer also benefits when patient dose is minimal because less radiation is scattered from the pt.
TRUE
T/F? The optimal xray image is formed when only indirect transmission photons reach the image receptor.
FALSE. When only direct transmission photons reach the image receptor.
T/F? Coherent scattering does not contribute to radiographic fog in mammography because breast tissue is gently but firmly compressed during their imaging procedure.
TRUE
T/F? During the process of Compton scattering, an X-ray photon interacts with an inner-shell electron of an atom of the irradiated object.
FALSE. An xray photon interacts with an outer shell electron.
T/F? A photoelectron usually is absorbed within a few micrometers of the medium through which it travels, thereby increasing patient dose and contributing to biologic damage in tissue.
TRUE
T/F? Absorption properties of different body structures must be identical to make diagnostically useful images possible.
Absorption properties of different body structures must be different.
T/F? The intensity of radiation scatter in various directions is a major factor in the planning of protection for medical imaging personnel during a radiologic examination.
TRUE
T/F? Pair production is also known as Rayleigh scattering.
FALSE. It is not.
T/F? In the radiographic kilovoltage range, compact bone with a high calcium content by weight undergoes much more photoelectric absorption than does an equal mass of soft tissue and air.
TRUE
