Exam 9: Image Quality

Which of the following factors affects in-plane spatial resolution? I. focal spot size II. detector cell size III. sampling frequency

Total data acquisition time is determined by: I. gantry speed II. helical pitch III. detector coverage

In general, a high-resolution reconstruction kernel produces a(n) ______________ noise level.

To sharpen the image, a(n) ___________ process is applied to modify the frequency contents of the projection before back-projection.

In-plane resolution is measured in terms of: I. line pairs/centimeter II. line pairs/millimeter III. line pairs/inch

Which of the following operator-controlled factors affects image noise? I. kilovoltage II. slice thickness III. detector cell size

Which theory states that the sampling interval (pixel size) has to be sufficiently small to support the reconstruction and visualization of small objects?

Both voluntary and involuntary motion appears as ____________ that are usually tangential to the high-contrast edges of the moving part.

Because the computed tomography acquisition and reconstruction process is band limited, the reconstructed image of a bar pattern is a blurred version of the original object.

Which of the following describes the scanner's ability to resolve closely placed objects that are significantly different in the background?

All of the following can be described as image quality parameters except:

Scatter-induced artifacts can be corrected with algorithms by carefully measuring or estimating the scatter distribution in the projection.

Low-contrast resolution can be measured with phantoms that contain low-contrast objects of different sizes.

All of the following can cause shading artifacts except:

In computed tomography, artifacts can arise from a number of sources, including the patient, inappropriate selection of protocols, reconstruction process, and problems relating to the equipment.

What refers to an increase in the mean energy of the x-ray beam as it passes through the patient?

What is an indication of a computed tomography system's ability to freeze motions of the scanned object?

What types of artifacts can arise from insufficient projection sampling or from insufficient view sampling?

Linearity can be checked by a yearly calibration test.

Metallic materials usually present as ____________ artifacts on the image.