RADIOLOGY I FINAL EXAM QUESTIONS AND ANSWERS
a dental hygienist needs radiographs on a pt who is only 4 years old. Compared to the exposure times
used for adult radiographs, the exposure times for young children are - -about half the time of exposure
used for adults
-A hygienist is taking a maxillary right canine PA using the paralleling technique. The usual position of
the PID is - -the PID is set up at positive vertical angulation and is pointed downward
-a hygienist uses a target-receptor distance of 16 in. The kVp is 65, mA is 10, and the exposure time is
0.48 seconds and produces a radiograph that is diagnostic. If she changes the target-receptor distance to
8 inches, what should be the new exposure time in seconds? - -0.12 seconds
-a mutation which produces change in the person exposed to ionizing radiation but does not produce
mutations in subsequent generations is known as - -somatic effect
-a passage through bone extendimg from the mandibular foramen to the mental foramen in known as
the - -mandibular canal
-a photon of x-radiation hits a molecule of water (H2O) in the pts tissues. the molecule becomes H and
OH. This is part of - -free radical formation
-a threshold in a dose-response relationship indicates that any dose, regarless of size can be expected to
produce a biologic response. A linear dose-response relationship indicates that the biologic response is
directly proportion to the dose. - -first statement is false, while the second is true.
-all of the following are characteristics of x-radiation EXCEPT - -it has mass and weight
-an indirect effect of x-rays on a biologic system is best demonstrated by - -hydrogen peroxide
production
-An organ that, if damaged, diminishes the quality of an individual's life is termed a: - -critical organ
-At a distance of 4 ft from the x-ray tube, the measurement of radiation is 80mSv. What would the
measurement of radiation be at a distance of 2 ft? - -320 mSv
-Both x-rays and visible light - -are considered part of the electromagnetic spectrum
-Causes foreshortening in a radiograph - -vertical angulation of BID is excessive
-Cells more sensitive to radiation - -rapidly dividing and young
-Coherent Scatter (Thompson scatter) is characterized by an x-ray photon that interacts with matter and
then: - -does not produce ionization but changes direction
, -cosmic radiation comes from outer space, the sun and stars. Terrestrial radiation refers to the inherent
radiation inside the x-ray machine. - -the first statement is true while the second is false.
-earliest clinical symptom of acute radiation syndrome is - -nausea and vomiting
-factors that would improve the sharpness of the image on a radiograph - -decrease the size of the focal
spot on the target
-For dental radiography, the req. diameter size of the radiation beam at the pts skin is - -2.75 inches
-Forms of particulate radiation - -alpha, beta, and cathode
-If a satisfactory radiograph was produced using a target-film distance of 8 inches and an exposure time
of 0.2 seconds with 75 kVp and 10 mA, what would be the correct exposure time for a target-film
distance of 16 in with 75 kVp and 10 mA. - -0.8 seconds
-If you decrease the distance b/w the tooth being x-rayed and the receptor, what change would occur in
the image? - -the image becomes larger (magnification)
-in a standard x-ray machine, about 70% of the x-radiations produced at the source in the x-ray tube are
called - -Bremsstrahlung
-in dental radiology, the quantity of x-rays produced in the x-ray tube is controlled by - -milliamperage
-in order to produce thermionic emission in the x-ray tube, this is req... - -the step-down transformer
and circuit
-in the practice of dentistry, the most freq reason for taking btwx (interproximal) radiographs is to
diagnose - -caries
-In the processed radiographic image, contrast is defined as the - -number of discernible shades of black,
white and gray
-in the x-ray tube, x-rays are produced by an electron stream which is traveling from - -the negative
cathode to the positive anode
-in which intra-oral PA are you most likely to find superior foramina of incisive canal? - -maxillary central
incisor
-increasing the kVp in a dental x-ray machine form 40 kVp to 80 kVp will produce radiographs that have
which characteristics? - -longer scale, lower contrast, many more shades of gray
-ionization is - -the gain or loss of electrons
-largest contributor to natural souces of background radiation in the US - -radon
-Most radiosensitive tissues - -hematopoietic
a dental hygienist needs radiographs on a pt who is only 4 years old. Compared to the exposure times
used for adult radiographs, the exposure times for young children are - -about half the time of exposure
used for adults
-A hygienist is taking a maxillary right canine PA using the paralleling technique. The usual position of
the PID is - -the PID is set up at positive vertical angulation and is pointed downward
-a hygienist uses a target-receptor distance of 16 in. The kVp is 65, mA is 10, and the exposure time is
0.48 seconds and produces a radiograph that is diagnostic. If she changes the target-receptor distance to
8 inches, what should be the new exposure time in seconds? - -0.12 seconds
-a mutation which produces change in the person exposed to ionizing radiation but does not produce
mutations in subsequent generations is known as - -somatic effect
-a passage through bone extendimg from the mandibular foramen to the mental foramen in known as
the - -mandibular canal
-a photon of x-radiation hits a molecule of water (H2O) in the pts tissues. the molecule becomes H and
OH. This is part of - -free radical formation
-a threshold in a dose-response relationship indicates that any dose, regarless of size can be expected to
produce a biologic response. A linear dose-response relationship indicates that the biologic response is
directly proportion to the dose. - -first statement is false, while the second is true.
-all of the following are characteristics of x-radiation EXCEPT - -it has mass and weight
-an indirect effect of x-rays on a biologic system is best demonstrated by - -hydrogen peroxide
production
-An organ that, if damaged, diminishes the quality of an individual's life is termed a: - -critical organ
-At a distance of 4 ft from the x-ray tube, the measurement of radiation is 80mSv. What would the
measurement of radiation be at a distance of 2 ft? - -320 mSv
-Both x-rays and visible light - -are considered part of the electromagnetic spectrum
-Causes foreshortening in a radiograph - -vertical angulation of BID is excessive
-Cells more sensitive to radiation - -rapidly dividing and young
-Coherent Scatter (Thompson scatter) is characterized by an x-ray photon that interacts with matter and
then: - -does not produce ionization but changes direction
, -cosmic radiation comes from outer space, the sun and stars. Terrestrial radiation refers to the inherent
radiation inside the x-ray machine. - -the first statement is true while the second is false.
-earliest clinical symptom of acute radiation syndrome is - -nausea and vomiting
-factors that would improve the sharpness of the image on a radiograph - -decrease the size of the focal
spot on the target
-For dental radiography, the req. diameter size of the radiation beam at the pts skin is - -2.75 inches
-Forms of particulate radiation - -alpha, beta, and cathode
-If a satisfactory radiograph was produced using a target-film distance of 8 inches and an exposure time
of 0.2 seconds with 75 kVp and 10 mA, what would be the correct exposure time for a target-film
distance of 16 in with 75 kVp and 10 mA. - -0.8 seconds
-If you decrease the distance b/w the tooth being x-rayed and the receptor, what change would occur in
the image? - -the image becomes larger (magnification)
-in a standard x-ray machine, about 70% of the x-radiations produced at the source in the x-ray tube are
called - -Bremsstrahlung
-in dental radiology, the quantity of x-rays produced in the x-ray tube is controlled by - -milliamperage
-in order to produce thermionic emission in the x-ray tube, this is req... - -the step-down transformer
and circuit
-in the practice of dentistry, the most freq reason for taking btwx (interproximal) radiographs is to
diagnose - -caries
-In the processed radiographic image, contrast is defined as the - -number of discernible shades of black,
white and gray
-in the x-ray tube, x-rays are produced by an electron stream which is traveling from - -the negative
cathode to the positive anode
-in which intra-oral PA are you most likely to find superior foramina of incisive canal? - -maxillary central
incisor
-increasing the kVp in a dental x-ray machine form 40 kVp to 80 kVp will produce radiographs that have
which characteristics? - -longer scale, lower contrast, many more shades of gray
-ionization is - -the gain or loss of electrons
-largest contributor to natural souces of background radiation in the US - -radon
-Most radiosensitive tissues - -hematopoietic
