CT Physics Quizzes 3

Only some of the information collected from the voxels that compose each of the scanned slices goes to the computer for image reconstruction.

False

Proper patient preparation is not important for the success of virtual colonoscopy.

False

The CT number for water is +1000.

False

The development of computed tomographic angiography and 3D imaging has not proved effective in the evaluation of cerebral aneurysms and arteriovenous malformations.

False

The results of preprocessing are referred to as image data.

False

True or False. Computer-aided diagnosis helps the observer view 3D space by displaying the front, back, top, and bottom of an object.

False

True or False. Multiplanar reconstruction creates three-dimensional images from the transaxial data set.

False

True or False. Studies have shown that virtual endoscopies would be more expensive than real endoscopies.

False

True or False. Surface rendered images are superior in all parameters like edge delineation, depiction of vessel lumen, and demonstration of overlapping structures.

False

True or False. The measurement of the total X-ray absorption of a particular ray is defined as a view.

False

True or False. The range of CT numbers is the WL.

False

Windowing is an example of a linear image manipulation technique.

False

Which of the following belongs to the class of nonlinear image manipulation techniques?

Gray-scale manipulation

Which algorithm provides a valuable perspective in defining lesions for surgical planning or detecting subtle small airway diseases?

Minimum intensity projection

The fact that noise in the reconstructed images is no longer white describes which spectrum?

Noise power spectrum (NPS)

Which of the following uses voxel information to transform the images into a collection of objects with subsequent processing concentrating on the display of the objects?

Object-based processing

Which stage of volume rendering assigns the different brightness levels or color to a voxel?

Preprocessing

__________ information is used to assess the three elements of technique of the 3D imaging procedure.

Quantitative

Which of the following basic visualization tools allows for the mean and standard deviation within a given ROI?

ROI statistics

An internal representation of surfaces that will be visible in the displayed image and then "lights" according to a standard protocol describes:

SR

What space does the x, y, and z coordinates define in which multidimensional data are represented?

Scene space

Which type of 3D imaging approach generates multiplanar reconstruction (MPR) (coronal and sagittal) images?

Slice imaging

Anatomy missed as a result of patient respiration can have what type of appearance on the final 3D image?

Stairstep artifact

Which is an example of a 3D rendering algorithm?

Surface rendering (SR)

True or False. Through the manipulation of CT numbers of the various tissues, the picture can be changed to show soft tissues and dense structures such as bone.

True

True or False. When the WL is centered on the lungs, the image display is optimized for the lungs.

True

True or False. Windowing is the most common image processing technique in CT.

True

Volume rendering produces 3D images that have a better image quality and provide more information compared with SR.

True

Voxel-based processing makes determinations about each voxel and decides to what degree each should contribute to the final 3D image.

True

What technique is used to virtually unroll, slice open, and display a 3D model of the colon?

Virtual dissection

Which of the following is a technique whereby 3D surfaces are extracted from a volume or whereby voxels are extracted from a volume into another 3D segmented region?

Volume extraction

Which type of 3D imaging approach produces a true 3D visualization?

Volume imaging

Which of the following optimizes the image display for a particular structure?

WL

Which of the following controls the contrast of the CT image?

WW

Which of the following are not categories of three-dimensional rendering?

Windowing

True or False. The signals that leave the CT detectors are subject to preprocessing.

True

In the scene (xyz) coordinate system, the axes are positioned at __________ angles.

90 degree

Which of the following removes the classical star pattern artifact of the back-projection algorithm?

FBP

Which of the following is an algorithm intended to create a thick MPR by using the average of the attenuation through the tissues of interest?

AIP

Which of the following refers to a defined set of instructions for solving a problem?

Algorithm

An examination of the abdomen has a WW of 400 and a WL of 0. Which of the following is true given these settings?

All structures between -200 and 200 will spread through the gray scale

A WL of -150 Hounsfield units (HU) is appropriate for viewing the lungs.

False

Convolution kernels can be applied to any type of data.

False

If the WW setting is 200 and the WL is 0, which of the following occurs?

CT numbers greater than +100 appear white

Which advanced tool in CT allows users to view a large set of images very quickly?

Cine visualization

Which of the following is a volumetric imaging technique that displays bone, soft tissue, and vessels at the same time?

Compositing

Which of the following describes the beam that diverges from the X-ray tube to the outer edges of the detectors?

Cone beam

MinIP is an algorithm that only the tissues with the greatest attenuation will be displayed for viewing by an observer.

False

One industry standard in data transfer and connectivity is:

Digital Imaging and Communications in Medicine (DICOM).

Which modeling technique transforms a 2D profile into a 3D object?

Extrusion

Which of the following algorithms is most commonly used in the state-of-the-art CT scanners?

FBP

In which of the following are pixels in a certain region of the image made to appear brighter?

Highlighting

Which is a mathematical technique used to estimate the value of a function from known values on either side of the function?

Interpolation

What term is in-plane resolution measured?

Line pairs/centimeter

Which of the following refers to the relationship of CT numbers to the linear attenuation coefficients of the object to be imaged?

Linearity

Which of the following is defined as the smallest object that can be visualized at a given contrast level and dose?

Low-contrast performance

Which of the following algorithms uses only the tissues with the greatest attenuation?

Maximum intensity projection

A large WW means a long gray scale.

True

A large cone beam will result in cone-beam artifacts.

True

Computed tomographic colonoscopy is an integral tool for the examination of colorectal polyp detection.

True

One advantage of virtual endoscopy is that it can reduce complications that might arise from conventional endoscopy.

True

Preset window settings allow CT scanners to simultaneously display two different density ranges (different WW and WL) in order to define two different anatomic areas.

True

Ray tracing involves a mathematical ray sent from the observer's eye through the 2D computer screen to pass through the 3D volume that contains opaque and transparent objects.

True

Semiautomatic segmentation allows the operator to select objects to be included in the VR image data set through the use of windowing.

True

The algorithms for the single-slice (SCCT) and MSCT scanners with four detector rows are referred to as spiral/helical fan-beam approximation algorithms.

True

The created multiplanar reconstruction images are poorer in quality than the obtained transaxial images.

True

True or False. An algorithm is a set of rules for solving a problem.

True

True or False. Image smoothing is an example of a linear image manipulation technique.

True

True or False. In SR, surface formation is the first step, and it involves the operation of contouring.

True

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

True

True or False. Most experts agree that SR is not best suited for use in CTVR imaging.

True

True or False. The purpose of 3D imaging is to use large amounts of data collected from the patient to provide both qualitative and quantitative information.

True

Volume rendering provides multiple benefits for virtual CT endoscopy except its ability to:

combine SR techniques.

Typical 3D processing techniques include software to perform all of the following except:

computer-aided diagnosis.

The first operation to which raw data is subjected is referred to as:

convolution

FBP is also referred to as the ______________ _______________.

convolution method

Virtual endoscopy allows the viewer to "fly through" each of these structures except:

cortical bone.

The creation of the simulated 3D image from data collected from the object space is called:

rendering.

Preprocessing involves the use of all of the following except:

delineation.

All of the following are major elements of a typical 3D imaging system except:

detector array.

Clinical applications of 3D imaging in CT include all of the following except:

endocrine system.

Windowing in CT is an example of:

gray-level mapping.

The next step after data acquisition that is intended to optimize the images before they are subject to further processing and analysis is:

image preprocessing.

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

increased

A large WW indicates that there is a relatively ______________ gray scale.

long

The generation of a 3D object by using computer software is called:

modeling

The fourth dimension involved in 4D angiography is ____________.

opacity

Hounsfield's first scanner used _________________ beam projections acquired through a 180-degree rotation.

parallel

The averaging of all tissues in a voxel is:

partial volume averaging.

The zero point is also called the:

point of intersection

Gray-level mapping belongs to the class of:

point processing technique.

All of the following are volume imaging methods except:

polygonal methods.

All of the following are shading algorithms except:

polygonal shading.

The WW in CT is the:

range of CT numbers.

The most familiar coordinate system is the:

scene coordinate system.

Algorithms for sliding thin slabs (STS) include all of the following except:

total intensity projection.

3D imaging has found applications in all of the following except:

ultrasound-guided biopsies.

Limitations of maximum intensity projections include each of the following except:

uses large amounts of data in the 3D space.

Virtual endoscopy includes all of the following applications except:

virtual arthroscopy.