Bontrager Chapter 18 Workbook

General CT number or range for this tissue type: Cortical bone

+1000

General CT number or range for this tissue type: Blood

+20

General CT number or range for this tissue type: White brain matter

+45

General CT number or range for this tissue type: Fat

-100

General CT number or range for this tissue type: Air

-1000

General CT number or range for this tissue type: Lung tissue

-200

General CT number or range for this tissue type: Water

0

The larger two ventricles (Right and left) have four significant parts: 1, 2, 3, 4; the small duct-like structure (4) provides communication between ventricles and (5) indicates a connection between the third and fourth ventricles; an important gland - 8. (7) represents an important communication with the subarachnoid space on each side of the fourth ventricle. 1. _____ (occipital) 2. _____ 3. _____ (frontal) 4. _____ (foramen) 5. _____ 6. _____ (temporal) 7. _____ 8. _____ (gland)

1. Posterior horn 2. Body 3. Anterior horn 4. Interventricular foramen 5. Cerebral aqueduct 6. Inferior horn 7. Lateral recess 8. Pineal gland

Calculate the pitch ratio using the following parameters: Couch movement at a rate of 20 mm per second with a slice collimation of 10 mm _____.

2 : 1 pitch

Approximately _____% to _____% of all cranial CTs require contrast media.

50 to 90%

The central nervous system can be divided into the following two main divisions:

A. Brain (encephalon) B. Spinal cord (medulla spinalis)

List the four groupings of cerebral nuclei (basal ganglia):

A. Caudate nucleus B. Lentiform nucleus C. Claustrum D. Amygdaloid nucleus

The fluid manufactured and stored in the ventricular system is called (A) _____, abbreviated as (B) _____. This fluid completely surrounds the brain and spinal cord by filling the space called the (C) _____ space. A blockage within this system may result in excessive accumulation of this fluid within the ventricles, creating a condition known as (D) ______.

A. Cerebrospinal fluid B. CSF C. Subarachnoid D. Hydrocephalus

The brain (encephalon) can be divided into three general divisions: the (1) forebrain, (2) midbrain, and (3) hindbrain. The forebrain and hindbrain are both divided into three divisions. List the three divisions of the forebrain and the hindbrain (secondary terms in parentheses): 1. Forebrain - A (Prosencephalon) - (Telencephalon)-largest division (Diencephalon) - B, C 2. Midbrain - (Mesencephalon) 3. Hindbrain - D (Rhombencephalaon) - E, F

A. Cerebrum B. Thalamus C. Hypothalamus D. Cerebellum E. Pons F. Medulla (medulla oblongata)

The cerebrospinal fluid-filled space and ventricular system are important in CT because these areas can be differentiated from tissue structures by their density differences. A. The larger spaces or areas within the CSF-filled space are called _____. B. The largest of these is the _____, located just posterior and inferior to the fourth ventricle.

A. Cisterns B. Cistern cerebellomedullaris (Cisterna magna)

The large cerebrum is divided into right and left hemispheres. Each hemisphere of the cerebrum is further divided into five lobes, with four of the lobes lying under the cranial bone of the same name. List these five lobes:

A. Frontal lob B. Parietal lobe C. Occipital lobe D. Temporal lobe E. Insula or central lobe

List the three primary components of a computed tomographic system:

A. Gantry B. Operator control console C. Computer

In general, the thin, outer cerebral cortex is (A) ________ matter, whereas the more centrally located brain tissue is (B) _______ matter.

A. Gray B. White

A. The optic chiasma, the site at which some of the optic nerves cross to the opposite side, is located in the _____, a division of the forebrain. B. An important gland that is located just inferior to this division of the forebrain is the _____.

A. Hypothalamus B. Pituitary (hypophysis) gland

Window level (WL) controls: A. Image brightness B. Image contrast C. Slice thickness D. Total number of slices

A. Image brightness

List the three significant structures associated with the hypothalamus:

A. Infundibulum B. Posterior pituitary gland C. Optic chiasma

A. At the level of the lower border of which vertebra does the solid spinal cord terminate? B. This tapered terminal area of the spinal cord is called the __________.

A. L1 B. Conus medullaris

Ventricles: There are four major cavities in the ventricular system; two of these ventricles are located within the right and left cerebral hemispheres and the remaining two are midline structures. Identify the four ventricles: A. Right and left __________ ventricles B. _________ ventricle C. ________ ventricle

A. Lateral B. Third C. Fourth

List the three primary structures of the brainstem:

A. Midbrain B. Pons C. Medulla

A. The specialized cells of the nervous system that conduct electrical impulses are called _________. B. The parts of these cells that receive the electrical impulse and conduct them toward the cell body are called _________.

A. Neurons B. Dendrites

Identify the three lobes of the right cerebral hemisphere and the deep fissure separating the two cerebral hemispheres. (NOTE: There is a fold of dura mater, called the falx cerebri, which extends deep within this fissure and which separates the two hemispheres that is visualized on CT scans.)

A. Occipital lobe B. Parietal lobe C. Frontal lobe D. Longitudinal fissure

There are 12 pairs of cranial nerves, most of which originate from the brainstem and travel to various parts of the brain, controlling both sensory and motor functions. List these 12 pairs of cranial nerves:

A. Olfactory B. Optic C. Oculomotor D. Trochlear E. Trigeminal F. Abducens G. Facial H. Acoustic I. Glossopharyngeal J. Vagus K. Spinal accessory L. Hypoglossal

Image archiving for most modern CT systems is performed through a(n): A. PACS B. Magnetic disk or tape C. Optical disk D. Laser printer

A. PACS

What is commonly injected following the administration of intravenous contrast media during a multislice CT scan? A. Saline B. Heparin C. Lasix D. Sterile water

A. Saline

With multi-detector CT systems, actual thickness of a tomographic slice is determined by: A. Size of detector row B. Pre-patient collimator C. Effective focal spot D. Post-patient collimator

A. Size of detector row

The depth of the voxels is determined by: A. Slice thickness B. Speed of computer C. Actual scan time D. Size of the pixel

A. Slice thickness

The CNS can be divided by appearance into white matter and gray matter, which can be differentiated by CT. The difference in appearance between these two is a result of their makeup. Describe this difference by indicating what each consist of: A. White matter: B. Gray matter:

A. Tracts of myelinated axons or nerve cells B. Primarily dendrites and cell bodies

The pitch ratio calculated in the previous question is an example of: A. Undersampling B. Oversampling C. Perfect pitch D. Intermittent pitch

A. Undersampling

List the four advantages of CT over conventional radiography:

A. Visualization of anatomic structures with no superimposition B. Increased contrast resolution between various types of soft tissue C. MPR (multiplanar reconstruction) D. Manipulation of attenuation data

CT scan detect tissue density differences as low as: A. ≤1% B. 10% C. 15% D. 20%

A. ≤1%

Pitch is defined as:

Amount of anatomy examined during a particular scan

The central opening in the CT support structure at which the patient is scanned is called the _________.

Aperture

Meninges and Spaces: Skull or cranium _____ (Spiderlike avascular membrane)

Arachnoid mater

CT numbers are a numerical scale that represents tissue ________.

Attenuation

What do the detectors measure in a CT system?

Attenuation of radiation by a given tissue

What type of shields can be used to minimize doses to radiosensitive organs (eye, breasts, pelvis, and thyroid)? A. Lead B. Bismuth C. Plastic acrylic D. Copper

B. Bismuth

Which aspect of the brain coordinates important motor functions such as coordination, posture, and balance? A. Pons B. Cerebellum C. Midbrain D. Cerebrum

B. Cerebellum

Window width (WW) controls: A. Displayed image density B. Displayed image contrast C. Slice thickness D. Total number of slices

B. Displayed image contrast

How must the intravenous contrast media be administered during a multislice CT scan? A. Hand, bolus injection B. Electromechanical injector C. Slow drip infusion D. Fast drip infusion

B. Electromechanical injector

Data sets from image voxels are referred to as: A. Bytes B. Isotropic C. Dimensions D. Spatial differences

B. Isotropic

What is the name of the large groove that separates the cerebral hemispheres? A. Anterior central gyrus B. Longitudinal fissure C. Central sulcus D. Posterior central gyrus

B. Longitudinal fissure

Which structure of the brain controls a wide range of body functions, including growth and reproductive functions? A. Pineal gland B. Pituitary gland C. Thalamus D. Hypothalamus

B. Pituitary gland

A scanogram or topogram is another term for: A. CT scan of the head B. Scout view C. Warm-up procedure for scanner D. Calibration procedure for scanner

B. Scout view

Most common appearance of the tissue type as displayed on a CT image: CSF

Black

The central midline portion of the brain connecting the midbrain, pons, and medulla to the spinal cord is called the _____.

Brainstem

Which of the following parameters would produce a 0.5 : 1.0 pitch ratio? A. 10-mm couch movement and 10-mm slice thickness B. 15-mm couch movement and 10-mm slice thickness C. 10-mm couch movement and 20-mm slice thickness D. 30-mm couch movement and 10-mm slice thickness

C. 10-mm couch movement and 20-mm slice thickness

Pixels represent varying degrees of: A. Resolution B. Contrast C. Attenuation D. Scatter radiation

C. Attenuation

Reconstruction of patient data into alternative planes (coronal, sagittal, three-dimensional) is termed: A. Algorithmic reconstruction B. 3-D reconstruction C. Multiplanar reconstruction D. Modulated reconstruction

C. Multiplanar reconstruction

Which of the following devices replaced high-tension cables in helical CT scanners? A. Microswitches B. Variable diodes C. Slip rings D. Optic fiber lines

C. Slip rings

Which aspect of the brain serves as an interpretation center for certain sensory impulses? A. Midbrain B. Pituitary gland C. Thalamus D. Hypothalamus

C. Thalamus

List the scintillation materials that make up the solid-state detector array:

Cadmium tungstate or rare earth oxide ceramic crystals

With a 512- x 512-image matrix, the CT processor must perform ________ mathematical calculations per slice. A. 128 B. 1280 C. 187,818 D. 262,144

D. 262,144

What is the name of the arches mass of transverse fibers (white matter) that connects the two cerebral hemispheres? A. Falx cerebri B. Anterior central gyrus C. Central sulcus D. Corpus callosum

D. Corpus callosum

What is the name of the technology that uses the optimal mAs per slice to minimize the patient dose during a CT scan? A. Modulation transfer function B. Scan-dose calibration C. Detector calibration D. Dose modulation

D. Dose modulation

Which aspect of the brain controls important body activities related to homeostasis? A. Pons B. Cerebellum C. Thalamus D. Hypothalamus

D. Hypothalamus

Which of the following is not an advantage of multislice CT scanners? A. Fast imaging speed B. Acquires large number of slices rapidly C. Minimizes patient motion D. Low-cost system to operate

D. Low-cost system to operate

Meninges and Spaces: Skull or cranium _____ (Outer "hard" or "tough" layer)

Dura mater

The surface of each cerebral hemisphere contains numerous grooves and convolutions or raised areas.

E. Anterior (precentral) central gyrus F. Central sulcus G. Posterior (postcentral) central gyrus

Meninges and Spaces: Skull or cranium _____ (Space or potential space)

Epidural space

True/False: Oxygen deprivation of 2 minutes will lead to permanent brain cell injury.

False; 4 minutes

True/False: Volume CT scanners are limited to one 360-degree rotation slice in the same direction.

False; multiple rotations possible

True/False: Iodinated contrast media are able to pass through the blood-brain barrier in the normal individual.

False; not able to pass through

True/False: The primary difference between each generation of CT scanners was the speed of the system.

False; number and arrangement of the detectors

Correct generation of CT scanner with these characteristics: 1- to 2-detector system

First generation

Correct generation of CT scanner with these characteristics: Scan times of 4 1/2 minutes per slice

First generation

Correct generation of CT scanner with these characteristics: 4800 or more detectors on a fixed ring

Fourth generation

Correct generation of CT scanner with these characteristics: The first type with fixed detectors rather than detectors rotation with an x-ray tube

Fourth generation

Correct generation of CT scanner with these characteristics: 1-minute scan time for entire exam (multiple answers)

Fourth generation and Multislice scanner

Which part of the CT system houses the x-ray tube, detector array, and collimators?

Gantry

Most common appearance of the tissue type as displayed on a CT image: Gray brain matter

Gray

Correct generation of CT scanner with these characteristics: 8 times faster than a 1-second, single-slice scanner

Multislice scanner

Correct generation of CT scanner with these characteristics: Capable of acquiring four or more slices simultaneously

Multislice scanner

Meninges and Spaces: Skull or cranium _____ (Inner "tender" layer)

Pia mater

A second important midline structure gland is the _____.

Pineal gland

Correct generation of CT scanner with these characteristics: First scanner with fan-shaped beam with 30 or more detectors

Second generation

Meninges and Spaces: Skull or cranium _____ (Wider space filled with cerebrospinal fluid)

Subarachnoid space

Meninges and Spaces: Skull or cranium _____ (Narrow space containing thin layer of fluid)

Subdural space

Pitch is a relationship between _____ and _____.

Table speed and slice thickness

Correct generation of CT scanner with these characteristics: Capable of volume scanning (multiple answers)

Third and Fourth generation

Correct generation of CT scanner with these characteristics: Continuous volume scanning (CVS) (multiple answers)

Third and Fourth generation

Correct generation of CT scanner with these characteristics: Contains a bank of up to 960 detectors

Third generation

Correct generation of CT scanner with these characteristics: First scanner to rotate a full 360 degrees around patient

Third generation

Correct generation of CT scanner with these characteristics: First scanner with large aperture, which permitted full body scanning

Third generation

What is the primary goal of the Image Gently campaign?

To strive to reduce dose to children during CT procedures through the application of accepted protocols, safety measures, and open dialogue with patients and the health care team.

True/False: Hard-copy images of axial CT scans are viewed as though the viewer as though the viewer were facing the patient.

True

True/False: Iodinated contrast media are often required to visualize neoplasms during a head CT scan.

True

True/False: Noninvasive studies of the heart are possible with multislice CT.

True

True/False: Terms such as "helical" and "spiral" are vendor-specific terms for volume CT scanners.

True

The outer "hard" or "tough" membrane described has an inner and outer layer tightly fused except for certain larger spaces between folds or creases of the brain and skull, which provide for large venous blood channels called _________.

Venous sinuses

What is the basic definition of the term voxel?

Volume element

Which medium serves as the baseline for CT numbers?

Water

Most common appearance of the tissue type as displayed on a CT image: Bone

White

Most common appearance of the tissue type as displayed on a CT image: Iodinated contrast media

White

Air would have a ________ (higher or lower) differential absorption as compared with soft tissue.

lower

A voxel is ______-dimensional image of the tissue, whereas a pixel is a ______-dimensional representation of the reconstructed image.

three; two