Question 1

Which of the following terms are synonymous?
1)Automatic exposure control
2)Iterative reconstruction
3)Tube current modulation

Accepted Answer

Automatic exposure control (AEC) and tube current modulation (TCM) are synonymous terms which refer to the automatic adjustment of radiation output during the radiographic examination. Iterative reconstruction is a different technique used in computed tomography to reduce image noise and improve image quality. Therefore, only option B is correct.

Question 2

A miscentering of ________ can produce as much as __________% increase in patient dose.

Accepted Answer

A miscentering of 2 cm can produce as much as a 25% increase in patient dose. The other options have either the wrong miscentering measurement or a higher percentage increase that is not supported by current literature.

Question 3

Tube current modulation in CT scanning can

Accepted Answer

Tube current modulation can help to reduce patient dose by automatically adjusting the tube current to the particular anatomy being scanned, so that less radiation is used in areas of the body where less attenuation is expected.

Question 4

In CT when a series of adjacent slices is obtained,some radiation will also scatter from the slice being made into the adjacent slices.What is this radiation called?

Accepted Answer

Interslice scatter radiation occurs when radiation is scattered from the slice being made into the adjacent slices. Backscatter is radiation that bounces back in the direction from which it came, forward scatter is radiation that scatters in the direction of the beam, and side scatter occurs when radiation scatters in a different direction from the incident beam direction.

Question 5

Which of the following is not typically used during a CT scan?
1)A tightly collimated x-ray beam
2)Direct patient shielding
3)Filtered back projection

Accepted Answer

Direct patient shielding is not typically used during a CT scan as it can interfere with the imaging process. A tightly collimated x-ray beam and filtered back projection are commonly used techniques during a CT scan.

Question 6

Verifying that the center of the patient coincides with the center of the CT gantry is a significant part of dose reduction strategies that is under the control of the

Accepted Answer

Verifying the center of the patient with the center of the CT gantry is a technical task that requires the expertise of the CT technologist operating the machine. Therefore, it is under the control of the CT technologist.

Question 7

For mammography molybdenum filters allow a (an)_________________ than rhodium filters.

Accepted Answer

Molybdenum filters allow a lower energy window than rhodium filters, which is particularly useful for imaging softer tissues such as those found in mammography.

Question 8

The entrance exposure from a CT examination may be compared with the entrance exposure received during which of the following procedures?

Accepted Answer

The answer of The entrance exposure from a CT examination...

Question 9

Lower tube current is used in anatomic regions where there is ____________ attenuation because the anatomy is ____________ or _________ dense.

Accepted Answer

Lower tube current is used in anatomic regions where there is decreased attenuation because the anatomy is thinner or less dense.

Question 10

In mammography maintaining and enhancing subject contrast is

Accepted Answer

Maintaining and enhancing subject contrast is of paramount importance for all patients in mammography as it helps in detecting small lesions and abnormalities that may indicate the presence of breast cancer.

Question 11

During mammography,axillary projections should be done only on request of the

Accepted Answer

The axillary view should not be done routinely and only when requested by the radiologist.

Question 12

In CT because of higher effective energy of the x-ray beam,both ____________ and _______________ interactions contribute substantially to the image.

Accepted Answer

In CT, the effective energy of the x-ray beam is high enough to cause both photoelectric and Compton interactions to occur substantially. Coherent and photodisintegration interactions occur at lower energies and are not as significant in CT imaging. Classical and pair production interactions occur at even higher energies and are not relevant to CT imaging.

Question 13

For routine head and body computed tomography examinations,effective doses fall into which of the following effective dose ranges?

Accepted Answer

Effective doses for routine head and body CT exams typically fall within the range of 1 to 10 mSv. Choices B, C, and D are too high and may indicate higher radiation doses for specialized or interventional CT procedures.

Question 14

With higher radiation exposure to the patient during a computed tomography examination,there is

Accepted Answer

Higher radiation exposure during a CT examination increases the associated cancer risk due to the ionizing radiation used, which can damage DNA and potentially lead to cancer in the long term.

Question 15

Digital mammography units with the ability to enhance contrast with image gray-level manipulation offer

Accepted Answer

Digital mammography units with contrast enhancement through gray-level manipulation offer substantial improvement for patients with dense breasts because it makes it easier to detect abnormalities within the dense breast tissue.

Question 16

DLP represents the product of the CTDIVOL and the irradiated scan length.In what unit of measure is it usually expressed?

Accepted Answer

DLP is usually expressed in mGy-cm, which represents the product of the CTDIVOL (mGy) and the irradiated scan length (cm).

Question 17

Filtering refers to changing the projection data before doing the back projections to remove the

Accepted Answer

Filtering in the context of image processing, particularly in applications like computed tomography (CT), is used to reduce blurriness in the images. This is achieved by modifying the projection data to enhance image quality, making structures within the image clearer and more distinct.

Question 18

Which of the following are relevant dose parameters in CT?
1)CT dose index (CTDI)
2)CTDIw
3)CTDIVOL
4)Dose length product (DLP)

Accepted Answer

All four parameters (CT dose index (CTDI), CTDIw, CTDIVOL, and Dose Length Product (DLP)) are relevant dose parameters in CT, used to measure and manage patient exposure to radiation.

Question 19

In spiral image acquisition,the patient table moves during the acquisition so that a

Accepted Answer

In spiral image acquisition, the patient table moves continuously during the acquisition, resulting in a three-dimensional data set being obtained. This data set can then be reconstructed into various image slices or volumes. Therefore, option B is the correct choice. Option A is incorrect because only a single image slice cannot be obtained from a spiral acquisition. Option C and D are incorrect as there are currently no methods available for obtaining four-dimensional or six-dimensional data sets in medical imaging.

Question 20

Which of the following terms are synonymous in relation to computed tomography?
1)Diagonal
2)Helical
3)Spiral

Accepted Answer

Helical and Spiral are synonymous terms in relation to computed tomography. Diagonal is not a commonly used term in CT so it is not synonymous with the other two.

Quiz 13: Special Considerations on Safety in Computed Tomography and Mammography

Which of the following terms are synonymous? 1) Automatic exposure control 2) Iterative reconstruction 3) Tube current modulation

A miscentering of can produce as much as __% increase in patient dose.

Tube current modulation in CT scanning can

In CT when a series of adjacent slices is obtained,some radiation will also scatter from the slice being made into the adjacent slices.What is this radiation called?

Which of the following is not typically used during a CT scan? 1) A tightly collimated x-ray beam 2) Direct patient shielding 3) Filtered back projection

Verifying that the center of the patient coincides with the center of the CT gantry is a significant part of dose reduction strategies that is under the control of the

For mammography molybdenum filters allow a (an) _________________ than rhodium filters.

The entrance exposure from a CT examination may be compared with the entrance exposure received during which of the following procedures?

Lower tube current is used in anatomic regions where there is ____ attenuation because the anatomy is or _ dense.