Deck 38: Computed Tomography Patient Radiation Dose

Question 1

Most modern CT scanners are _______________________ technology.

A) first-generation
B) second-generation
C) third-generation
D) fourth-generation

Answer 1

third-generation

Question 2

Which of the following data needs to be known to determine effective dose in CT?

A) Age of the patient
B) Original x-ray beam intensity
C) The tissues irradiated
D) A and C

Answer 2

A and C

Question 3

The combination of output radiation intensity and volume of tissue imaged is called ________________________.

A) computed tomography dose index
B) dose modulation
C) dose length product
D) effective diameter

Answer 3

dose length product

Question 4

Because CT uses a cone-shaped x-ray beam, scatter radiation is ______________, and contrast resolution is ____________.

A) reduced significantly, improved
B) reduced significantly, decreased
C) increased significantly, improved
D) increased significantly, decreased

Question 5

CT tissue dose is approximately ____________ the average fluoroscopic dose.

A) less than
B) equal to
C) greater than
D) incomparable

Question 6

Which two dimensions are measured to engage the Size-Specific Dose Estimate (SSDE)?

A) Transverse and lateral
B) Lateral and AP
C) AP and transverse
D) AP and sagittal

Question 7

U.S. Public Health Service data suggests that CT examinations currently account for approximately ________ of total patient effective dose.

A) 10%
B) 25%
C) 50%
D) 70%

Question 8

During helical CT, at a pitch of 1.0, the patient radiation dose is approximately ____________ that of conventional CT.

A) less than
B) equal to
C) greater than
D) incomparable

Question 9

The __________ collimators define the cone beam and the ________ collimators further reject scatter radiation.

A) prepatient, predetector
B) predetector, prepatient
C) prepatient, postpatient
D) postpatient, predetector

Question 10

The collimator that improves image contrast by limiting the amount of scatter radiation that reaches the detector is the ____________________.

A) prepatient collimator
B) postpatient collimator
C) A and B
D) None of the above

Question 11

In multislice helical CT, the dose profile tail is called ____________.

A) umbra
B) penumbra
C) vignetting
D) pin-cushion appearance

Question 12

Overranging occurs because of ___________________.

A) irradiated tissue overlapping
B) the pitch is one
C) the x-ray beam dose tail
D) All of the above

Question 13

A pitch of 1 indicates that with each rotation of the tube, the patient will move _________.

A) 8 cm
B) 16 cm
C) 24 cm
D) 32 cm

Question 14

Typical CT doses range from ___________________ during head imaging and from __________ during body imaging.

A) 20 to 40 mGyt (2000 to 4000 mrad), 20 to 40 mGyt (2000 to 4000 mrad)
B) 20 to 40 mGyt (2000 to 4000 mrad), 30 to 50 mGyt (3000 to 5000 mrad)
C) 30 to 50 mGyt (3000 to 5000 mrad), 20 to 40 mGyt (2000 to 4000 mrad)
D) 30 to 50 mGyt (3000 to 5000 mrad), 30 to 50 mGyt (3000 to 5000 mrad)

Question 15

In CT imaging, as with radiography, patient dose is ________________ to x-ray beam intensity and ___________________ to the average beam energy.

A) proportional, directly proportional
B) not proportional, directly proportional
C) proportional, indirectly proportional
D) not proportional, indirectly proportional