During a CT procedure, attenuation of the x-ray beam may be caused by which three
of the following? (Select three)
A. Coherent Scattering
B. Bremsstrahlung Radiation
C. Compton scattering
D. Photoelectric Absorption
E. Characteristic Radiation
Give this one a try later!
A. Coherent Scattering, C. Compton scattering, & D. Photoelectric
Absorption
During a CT procedure, attenuation of the x-ray beam may be caused by
coherent scattering, photoelectric absorption, and Compton scattering.
Attenuation refers to any interaction in which the x-ray beam decreases in
intensity. Coherent scattering, photoelectric absorption, and Compton
scattering all have the potential to remove photons from the useful beam
and cause attenuation. Bremsstrahlung and Characteristic radiation refer to
, x-ray production processes in the x-ray tube, not interaction mechanisms in
matter.
Concerning radiation-induced cancer, increasing the radiation dose to a patient
results in:
A. Increased severity of cancer
B. Decreased severity of cancer
C. Increase probability of cancer
D. Decreases probability of cancer
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C. Increase probability of cancer
Increasing radiation dose increases the probability of cancer, but it does
not increase the severity of cancer. A cancer caused by 3 Gray (Gy) of
radiation is no worse than a cancer caused by 2 Gy of radiation. Radiation
dose only affects the total probability.
Which of the following values represents a normal Computed Tomography Dose
Index (CTDI) of a pediatric CT head?
A. 75 milligray (mGy)
B. 85 milligray (mGy)
C. 40milligray (mGy)
D. 20 milligray (mGy)
Give this one a try later!
, C. 40milligray (mGy)
A normal value of the CTDI of a pediatric CT head is 40 mGy. According to
the American College of Radiology (ACR), a pediatric head scan on a 5
year old patient should not exceed 40 mGy. A CTDI higher than this level
may indicate that inappropriate technical parameters were used.
During a CT study, the technologist decreases the beam width (increases collimation).
What effect will this have on patient dose?
A. Increased patient dose
B. Decreased patient dose
C. No change in patient dose
Give this one a try later!
A. Increased patient dose
Decreasing the beam width actually increases the patient dose (this is
opposite of general radiography). This relates to the penumbra radiation
outside of the useful beam. When a smaller more collimated beam is used,
this creates more penumbra and an increase in patient dose.
While positioning a patient for CT of the chest, the technologist does not center the
patient in the center of the gantry. The scanner is using a variable milliamperage (mA).
This error is most likely to result in:
A. Increased patient dose
B. Decreased contrast resolution
C. Beam-hardening artifact
D. Increased image magnification
Give this one a try later!
, A. Increased patient dose
Incorrect patient positioning can cause an increase in patient dose when
using a variable mA. This is because the patient will look bigger on the
scout images and the scanner will increase the mA accordingly. There will
be no change in contrast resolution, no beam hardening, and no
magnification on the helical images.
A CT examination of the head used a fixed technique of 300 milliamperage (mA), 1.0
second rotation time, and 140 kilovoltage peak (kVp). The resulting Computed
Tomography Dose Index (CTDI) was 69 milligray (mGy). If the technique is changed to
120 kVp, how will the patient dose change?
A. Decrease patient dose
B. Increase patient dose
C. No change in patient dose
Give this one a try later!
A. Decrease patient dose
In this scenario, if the technique is changed to 120 kVp, the patient dose will
decrease. Changes in kVp have a significant effect on patient dose. As kVp
increases, the patient dose also increases.
How does decreasing kilovoltage (kVp) affect patient dose?
A. Increased patient dose
B. Decreased patient dose
C. No change in patient dose
Give this one a try later!
of the following? (Select three)
A. Coherent Scattering
B. Bremsstrahlung Radiation
C. Compton scattering
D. Photoelectric Absorption
E. Characteristic Radiation
Give this one a try later!
A. Coherent Scattering, C. Compton scattering, & D. Photoelectric
Absorption
During a CT procedure, attenuation of the x-ray beam may be caused by
coherent scattering, photoelectric absorption, and Compton scattering.
Attenuation refers to any interaction in which the x-ray beam decreases in
intensity. Coherent scattering, photoelectric absorption, and Compton
scattering all have the potential to remove photons from the useful beam
and cause attenuation. Bremsstrahlung and Characteristic radiation refer to
, x-ray production processes in the x-ray tube, not interaction mechanisms in
matter.
Concerning radiation-induced cancer, increasing the radiation dose to a patient
results in:
A. Increased severity of cancer
B. Decreased severity of cancer
C. Increase probability of cancer
D. Decreases probability of cancer
Give this one a try later!
C. Increase probability of cancer
Increasing radiation dose increases the probability of cancer, but it does
not increase the severity of cancer. A cancer caused by 3 Gray (Gy) of
radiation is no worse than a cancer caused by 2 Gy of radiation. Radiation
dose only affects the total probability.
Which of the following values represents a normal Computed Tomography Dose
Index (CTDI) of a pediatric CT head?
A. 75 milligray (mGy)
B. 85 milligray (mGy)
C. 40milligray (mGy)
D. 20 milligray (mGy)
Give this one a try later!
, C. 40milligray (mGy)
A normal value of the CTDI of a pediatric CT head is 40 mGy. According to
the American College of Radiology (ACR), a pediatric head scan on a 5
year old patient should not exceed 40 mGy. A CTDI higher than this level
may indicate that inappropriate technical parameters were used.
During a CT study, the technologist decreases the beam width (increases collimation).
What effect will this have on patient dose?
A. Increased patient dose
B. Decreased patient dose
C. No change in patient dose
Give this one a try later!
A. Increased patient dose
Decreasing the beam width actually increases the patient dose (this is
opposite of general radiography). This relates to the penumbra radiation
outside of the useful beam. When a smaller more collimated beam is used,
this creates more penumbra and an increase in patient dose.
While positioning a patient for CT of the chest, the technologist does not center the
patient in the center of the gantry. The scanner is using a variable milliamperage (mA).
This error is most likely to result in:
A. Increased patient dose
B. Decreased contrast resolution
C. Beam-hardening artifact
D. Increased image magnification
Give this one a try later!
, A. Increased patient dose
Incorrect patient positioning can cause an increase in patient dose when
using a variable mA. This is because the patient will look bigger on the
scout images and the scanner will increase the mA accordingly. There will
be no change in contrast resolution, no beam hardening, and no
magnification on the helical images.
A CT examination of the head used a fixed technique of 300 milliamperage (mA), 1.0
second rotation time, and 140 kilovoltage peak (kVp). The resulting Computed
Tomography Dose Index (CTDI) was 69 milligray (mGy). If the technique is changed to
120 kVp, how will the patient dose change?
A. Decrease patient dose
B. Increase patient dose
C. No change in patient dose
Give this one a try later!
A. Decrease patient dose
In this scenario, if the technique is changed to 120 kVp, the patient dose will
decrease. Changes in kVp have a significant effect on patient dose. As kVp
increases, the patient dose also increases.
How does decreasing kilovoltage (kVp) affect patient dose?
A. Increased patient dose
B. Decreased patient dose
C. No change in patient dose
Give this one a try later!
