CT Scan Flashcards
(276 cards)
1
Q
What is an advantage of scans of pituitary taken in coronal plane?
A
streak artifacts are reduced or eliminated
2
Q
Which two strategies can reduce the effect of dental fillings in sinus study?
A
Adjust the angle of the gantry and widen the window width.
3
Q
Which of the following conditions may be visualized in a CT study of the brain?
A
☑️Glioblastoma
4
Q
Which of the following is affected by the slice spacing in a CT study?
A
Radiation dose to the patient
5
Q
What is the name of the pinecon-shaped structure of the brain the can often be seen as calcified in CT images?
A
Pineal Gland
6
Q
What helical or spiral computed tomography term is defined as the table increment in distance per mm per 360 degrees gantry rotation divided by the section thickness in mm?
A
Pitch
7
Q
What effect would an array processor failure have on image processing?
A
Increase image display time
8
Q
Which of the following will magnify the image?
A
Decreasing field of view
9
Q
Which of the following is convolution?
A
☑️Filtered back projection
✖️Fourier transform
✖️Iterative filtration
✖️3-d rendering
10
Q
The muscles of mastication include all of the following EXCEPT the:
A
✖️Temporalis
☑️Proximal pterygoid
✖️Masseter
✖️Lateral pterygoid
11
Q
The gantry angle for a sinus cavity CT scan should be:
A
Parallel to the roof of the hard palate
12
Q
The ______lobe of the brain is responsible for visual perception
A
Occipital
13
Q
The larynx is best visualized with axial slices that are:
A
Parallel to the plane of the inferior aspect of the mandible
14
Q
The preferred type of external storage devices used on CT scanning computers is:
A
Magnetic optical disk (MOD)
15
Q
The internal ear contains all of the following structures EXCEPT the:
A
☑️Malleus
✖️Cochlea
✖️Semicircular canals
✖️Vestibule
16
Q
The recommended maximum slice thickness for display of CT scans of the abdomen and pelvis is _____mm.
A
6-7mm
17
Q
Which of the following artifacts is also referred to as the cupping artifact?
A
Beam hardening artifact
18
Q
Scan coverage for a temporal bone scan should cover the:
A
Mid mastoids to above the petrous ridge
19
Q
Contrast agents provide superior visibility in an anatomic area due to their ability to absorb:
A
X-ray photons
20
Q
The technique of ______is best described as capturing cardiac CT images using estimates of the patient’s RR interval based on initial electrocardiographic recordings of these intervals:
A
Prospective triggering
21
Q
Which superficial anterior muscle of the neck is known as the “muscle of facial expression”?
A
Platysma
22
Q
What is an appropriate length of scan delay in seconds following contrast injection for CT angiography of the brain?
A
15-17
23
Q
If extravasation of contrast occurs, the technologist should do all of the following EXCEPT:
A
☑️Remove the needle
☑️Elevate the affected limb
☑️Maintain pressure on the vein until the bleeding has stopped
✖️Apply heating pads to the area of extravasation
24
Q
The spinal cord originates at the foramen magnum in the skull base and extends approximately to the level of:
A
T12
25
The ideal kVp/mAs settings for a posterior fossa scan are:
120-140/200
26
In an electron beam CT (EBCT) scanner, the type of radiation used to produce the image is:
Fixed electron beam
27
Which one of the following is NOT a factor affecting choice of a particular contrast agent?
An institutional contract with the manufacturer Cost The use of drip infusion vs power injector Radiologist preference
✖️An institutional contract with the manufacturer
☑️Cost
✖️The use of drip infusion vs power injector ✖️Radiologist preference
28
What are the most appropriate filming parameters/formats for the subdural area of the brain?
250/50
29
What is the most common indication for CT of the hip?
Trauma
30
In addition to having the patient raise the arms above the head, technologists can minimize scan artifacts in musculoskeletal CT imaging by:
Optimizing the DFOV to include only region of interest
31
The roughened surface on the anterior surface of the tibia that provides an insertion point for the knee cap ligaments is the:
Tibial tuberosity
32
For pituitary scans, intravenous contrast should be injected at a rate of ___cc/sec
1
33
In abdominal and pelvic CT imaging, IV contrast provides all of the following benefits EXCEPT:
✖️Visualizing the layers of the peritoneal membrane ☑️Increasing the attentuation of pelvic blood vessels
☑️Assessing the vascularity of tumors ☑️Increasing the attenuation of solid organs
34
The dorsal tendon group is responsible for:
Extending the fingers and wrist
35
Which of the following statements regarding CTA of the abdomen is FALSE?
✖️Rate of injection is inversely proportional to contrast enhancement
☑️ CTA plays an important role in identifying vessel dissection
☑️Stent placement can be evaluated with CTA following surgical blood vessel repair
☑️The speed of CTA makes it a valuable tool for assessment of trauma patients
36
The measure of the total number of particles in contrast solution per kilogram of water describes:
Osmolality
37
The onset of most serious adverse reactions to contrast media occurs ______ post administration
Within 5 minutes
38
The sciatic nerve carries nerve fibers from the vertebral interspaces most prominently at:
L3-L5
39
The correct Hounsfield unit measurement for acute intracranial hemmorhage is:
55-75
40
The gelatinous core at the center of an intervertebral disc is called the:
Nucleus pulposus
41
The major change in CT technology seen with fourth-generation scanners was:
The use of up to 2000 detectors in a fixed ring
42
The Agaston score is a measurement of the:
Degree of coronary artery calcification
43
Spiral/helical CT:
Involves continuous scanning around the patient and table
44
In CT scanning of the wrist, the technologist should employ all of the following techniques EXCEPT:
☑️Use of the smallest possible DFOV
☑️Construction of images with an overlap
✖️Use of a wide collimation
☑️Acquisition of both coronal and sagittal images
45
Which one of the following statements regarding CT scans for air trapping are TRUE?
✖️Expiratory scans will show an increase in attenuation compared with inspiratory scans
✖️Expiratory scans are not needed with multidetector CT scanners
✖️Very thin slice thicknesses are used for diagnosis
☑️The Housfield Unit number is expected to be very high on the inspiratory scan
46
An appropriate length of scan delay in seconds following contrast injection for orbital scan is:
60
47
Adverse reactions to contrast media include all of the following EXCEPT:
☑️Dyspnea
☑️Hypotension
✖️A feeling of warmth
☑️Urticaria
48
Which one of the following is NOT a structure of the eyeglobe?
☑️Anterior lens
☑️Vitreous fluid
✖️Posterior lens
☑️Cornea
49
What is considered a normal range for Blood Urea Nitrogen (BUN)?
5-25 mg/dl
50
Which CT Procedure requires Prothrombin Time (PT) and Partial Thromboplastin Time (PTT) laboratory results prior to starting the procedure?
Such procedures may include all types of CT Guided Biopsies of any area, CT Guided drainages, and Ablations. If the PT or PTT are abnormal, the procedure may be cancelled.
51
What method must be utilized for all peripheral venipuncture procedures to reduce the risk of microbial contamination and infection?
Aseptic Technique is a method that prevents the introduction of unwanted organisms into an environment that may cause an infection.
52
What are the three phases of IV contrast enhancement?
The first phase of enhancement is the Bolus phase. This is an optimal phase for CTAs. There is a significant density difference between the abdominal aorta and IVC. The second phase is the Non-Equilibrium phase. During this phase, the bolus disperses into the capillaries then into the veins. The two phases of enhancement within this phase are the Hepatic Arterial and Portal Venous. The Non-Equilibrium phase provides the best differentiation of structures in soft tissue like the liver and pancreas. The third phase is Equilibrium. During this phase, the concentration of contrast in the veins and arteries are similar and soft tissue differentiation becomes diminished.
53
What type of IV contrast is the same or less osmolality as blood?
Non ionic
54
The basilar artery divides to form the _______arteries
Posterior Cerebral Arteries
55
Common causes of RLQ pain that may mimic appendicitis, but can be ruled out with CT scanning, include all of the following EXCEPT:
☑️Cecal diverticulitis
✖️Food poisening
☑️Crohn's disease
☑️Pelvic inflammatory disease
56
Signs of anaphylactoid reaction to contrast include all of the following EXCEPT:
✖️Yellowing of the skin
☑️Cool, clammy skin
☑️Throat constriction
☑️A sense of apprehension
57
The bone that transmittes the weight of the body from the distal portions of the tibia and fibula to the foot is called the:
Talus
58
To obtain 3D images of the spine, scanning should be conducted using a minimum slice thickness of ___mm and an overlap of ____%.
1,50
59
The term "noise" in CT imaging refers to:
Deviations in the consistency of the image grid
60
The extraocular muscles of the orbital muscle cone include all of the following EXCEPT the:
☑️Superior recti
☑️Inferior recti
✖️Lateral obliques
☑️Inferior obliques
61
What are the proper kVp/mAs settings for a scan of the soft tissues of the neck?
120-140/300
62
Gastric tumors most commonly appear on CT as:
Localized thickening of the gastric wall
63
The maximum degree of percentage of overlap that most CT scanners will recognize
50
64
Attachment of the vertebral column to the pelvis is provided by the:
SI Joint
65
The device in the gantry that measures the intensity of the x-ray beam emanating from the tube is called the:
Air-reference detector
66
Which of the following terms is used to describe the effectiveness with which the detectors gather the photons transmitted from the patient?
Capture efficiency
67
Second-generation scanners were associated with the introduction of which of the following developments?
A fan beam technology
68
The function of the detector is to:
Measure attenuated x-rays and convert them to digital signals
69
The blood vessel of the lower extremity that is the major source of thrombi leading to pulmonary embolism is the:
Popliteal vein
70
The ______ muscle of the rotator cuff is responsible for providing outward rotation of the arm
Infraspinatus
71
The _______muscle provides the strongest flexing action for the hip
Iliopsoas
72
The intervertebral foramina:
Allow for the ingress and egress of nerve root
73
The recommended display slice thickness for a routine cervical spine scan using a 16-slice CT scanner is ____mm.
2
74
For a CT scan of the lumbar spine requiring contrast, the contrast should be injected at a rate of ___ cc/sec.
1-2
75
The _______ligament is primarily responsible for stabilizing the anterior portion of the hip joint
Iliofemoral
76
The _______ligament is primarily responsible for stabilizing the anterior portion of the hip joint
The scan should begin following administration of the total contrast dose
77
What is the main advantages of CT over conventional radiography
☑️the elimination of superimposed structures
☑️the ability to differentiate small differences in density of anatomic structures and abnormalities
☑️the superior quality of the images.
78
The thickness of the the cross-sectional slice is referred to as its
Z Axis
79
Define pixel, voxel, and matrix.
Pixel- Picture element, an individual matrix and each pixel is assigned a CT number.
Matrix-Series of rows and columns of pixels that give form to the digital image
80
Determines the quanity of HU or the range of CT numbers used to map signals into shades of gray for specific windows.
Window width
81
Specific numbers are assigned to an individual pixels within the image data.
Hounsfield Unit
82
Minimum CT scan times have been reduced from 5 minutes per slice in 1976 to _____seconds per slice in 2004.
0.375
83
Partial thromboplastin time (PTT) measures the time required:
For clot formation in normal plasma
84
The most common reason to perform CT scanning of the lumbar spine is to:
Evaluate disc herniations
85
The field of view for pituitary gland scans should be ____cm.
10-12cm
86
A proper IV contrast bolus for a soft-tissue scan of the neck is ___cc at ____cc/sec
20, 2
87
The posterior elements of the vertebra are the:
Pedicles, laminae
88
The posterior margin of the posterior neck muscle triangle is formed by the_______ muscle.
Trapezius
89
The correct Hounsfield unit measurement for acute intracranial hemmorhage is:
55-75
90
The ______ ligament is responsible for preventing hyperextension of the vertebral column
Anterior Longitudinal
91
Using a multidetector-row scanner, the proper slice thickness used to reconstruct the hip is ___ mm.
3-5
92
How many display fields of view are recommended to obtain a complete CT scan of the neck?
3
93
CTA may require LOCM injection rats as high as ______mL/sec.
5
94
How man cc of contrast is appropriate to deliver for a routine brain scan?
100
95
IV contrast is used in CT scans of the hip and pelvis to:
Allow concomitant mapping of the iliac and femoral vessels
96
The portion of the dura mater that separates the cerebellum from the cerebrum is known as the :
Falx Cerebri
97
Third generation (rotate/rotate) scanners overcame which of the following limitations?
Translation motion
98
Which of the following is the term used to describe a voxel value that is the average of multiple tissue types contained within the voxel?
Partial Volume Averaging
99
Which of the following CT numbers would appear as a gray shades when a window width of 300 and a window level of 0 are selected?
Ct numbers between +150 and -150
100
Which fo the following is the central value in a range of gray shades used to display the image?
Window Level
101
What is the most common type of film used to recore CT exams?
Single Emulsion
102
What is the appropriate compensation to avoid quantum noise when performing thin section computed tomography?
Increase mAs
103
Which describes the relationship between section thickness and noise?
If section thickness increases, noise decreases
104
What term is used to describe as the ability to display an image of a large object that is only slightly different in density from its surroundings?
Contrast Resolution
105
Which of the following should be viewed with relatively wide window widths?
Lung and inner ear
106
How often should an average CT number water calibration test be performed?
Daily
107
Which of the following accurately describes the relationship between patient dose and pitch?
If pitch increases, patient dose decreases
108
Which of the following is defined as the ability to distinguish details in objects of different densities a small distance apart?
Spatial Resolution
109
What is the term that is used to describe contrast resolution?
Low contrast detectibilty
110
What is the primary type of interaction that contributes to the subject contrast in CT images?
Compton Scattering
111
What type of scan geometry is responsible for producing ring artifacts?
Rotate-Rotate
112
What is the cause for the "cupping" artifact?
The body hardens the beam thus lowering the attenuation numbers in the center
113
What anatomical structure forms a roof over the posterior cranial fossa and is shaped like a tent?
Tentorium cerebelli
114
The viscosity of a contrast agent refers to:
The rate at which the agent can be heated to room temperature
115
For the evaluation of herniated dics, CT provides _____________over MRI.
Superior visulization of bony abnormalities related to disc disease
116
The spinal cord originates at the foramen magnum in the skull base and extends approximately to the level of:
T12
117
A CT scan of the cervical spine should extend from the:
Axis to T1
118
Uniphasic, biphasic, and exponential decay all describe types of:
Phase enhancement
119
Continuous rotation scanners made___________imaging possible.
Helical
120
Attenuation data must be converted into ___________ format for the array processor.
Digital
121
Most CT scanners today use____________ detectors in which the x-ray photon causes the detector to generate a flash of light.
Solid state
122
The detectors measure attenuation data from various projections and is contained in the__________.
Raw Data
123
Beam hardening refers to:
the increase in the average energy of the photons that reach the detectors
124
Which window settings provides the best tissue differentiation of the soft tissues of the abdomen?
Window width = 300, window level = 40
125
Which of the following are possible results of partial voluming?
☑️misleading CT numbers
| ☑️decreased sharpness of edge
126
The heating unit on a power injector is for _____ of the contrast agent.
Decreasing viscosity
127
Which strategies minimizes beam hardening artifact from dense contrast media?
☑️the contrast solution can be diluted
☑️the scan can be performed in the opposite direction
☑️the scan can be performed with a slight delay
128
Is responsible for partial volume averaging?
Slice thickness
129
The normal range for prothrombin time (PT) is
10 to 14 seconds.
130
The viscosity of a contrast agent refers to:
The rate at which the agent can be heated to room temperature
131
For the evaluation of herniated dics, CT provides _____________over MRI.
Superior visulization of bony abnormalities related to disc disease
132
The spinal cord originates at the foramen magnum in the skull base and extends approximately to the level of:
T12
133
A CT scan of the cervical spine should extend from the:
Axis to T1
134
Uniphasic, biphasic, and exponential decay all describe types of:
Phase enhancement
135
Continuous rotation scanners made___________imaging possible.
Helical
136
Attenuation data must be converted into ___________ format for the array processor.
Digital
137
Most CT scanners today use____________ detectors in which the x-ray photon causes the detector to generate a flash of light.
Solid state
138
The detectors measure attenuation data from various projections and is contained in the__________.
Raw Data
139
Beam hardening refers to:
the increase in the average energy of the photons that reach the detectors
140
Which window settings provides the best tissue differentiation of the soft tissues of the abdomen?
Window width = 300, window level = 40
141
Which of the following are possible results of partial voluming?
☑️misleading CT numbers
| ☑️decreased sharpness of edge
142
The heating unit on a power injector is for _____ of the contrast agent.
Decreasing viscosity
143
Which strategies minimizes beam hardening artifact from dense contrast media?
☑️the contrast solution can be diluted
☑️the scan can be performed in the opposite direction
☑️the scan can be performed with a slight delay
144
Is responsible for partial volume averaging?
Slice thickness
145
The viscosity of a contrast agent refers to:
The rate at which the agent can be heated to room temperature
146
For the evaluation of herniated dics, CT provides _____________over MRI.
Superior visulization of bony abnormalities related to disc disease
147
The spinal cord originates at the foramen magnum in the skull base and extends approximately to the level of:
T12
148
A CT scan of the cervical spine should extend from the:
Axis to T1
149
Uniphasic, biphasic, and exponential decay all describe types of:
Phase enhancement
150
Continuous rotation scanners made___________imaging possible.
Helical
151
Attenuation data must be converted into ___________ format for the array processor.
Digital
152
Most CT scanners today use____________ detectors in which the x-ray photon causes the detector to generate a flash of light.
Solid state
153
The detectors measure attenuation data from various projections and is contained in the__________.
Raw Data
154
Beam hardening refers to:
the increase in the average energy of the photons that reach the detectors
155
Which window settings provides the best tissue differentiation of the soft tissues of the abdomen?
Window width = 300, window level = 40
156
Which of the following are possible results of partial voluming?
☑️misleading CT numbers
| ☑️decreased sharpness of edge
157
The heating unit on a power injector is for _____ of the contrast agent.
Decreasing viscosity
158
Which strategies minimizes beam hardening artifact from dense contrast media?
☑️the contrast solution can be diluted
☑️the scan can be performed in the opposite direction
☑️the scan can be performed with a slight delay
159
Is responsible for partial volume averaging?
Slice thickness
160
is the expected result of a CT Number Calibration Test performed on a water phantom?
0 +/- 3
161
cone beam artifact may look like stars:
Coming from structures around the edge of the image
162
How would the artifact from a faulty detector element appear on a localizer image?
A line parallel to the long axis of the patient table
163
In what orientation would the image be acquired to depict mastoiditis?
Transverse
164
Which of the following would decrease the effects of beam hardening artifacts?
Increase KVp
165
Which of the following would be used to better visualize low contrast resolution?
Narrow window width
166
Which of the following affects beam hardening?
☑️the energies of the photons in the beam
☑️the thickness of the tissues traversed by the beam
☑️the types of tissues the beam passes through
167
What is the cause of cone beam artifacts?
The use of a standard filtered back projection reconstruction
168
An injection rate of _____ ml/sec. will maintain a dense bolus of IV contrast media for a CTA examination and will be tolerated by most patients.
4-5
169
On MDCT, the final reconstructed slice thickness is determined by the:
Number of rows of detectors and the size of the detectors whose attenuation data gets combined
170
On a CT image of the brain a cupping artifact would appear brighter:
At the periphery of the brain
171
Using _____ reconstruction filter would decrease the appearance of noise in a CT image.
Smooth
172
________________ is the thickness of the slice that is actually represented on the CT image. It is not the slice thickness selected by the collimator opening. In axial scanning, the selected slice thickness is equal to the effective slice thickness. In helical scanning, the effective slice thickness is usually wider than the selected slice thickness due to interpolation.
Effective slice thickness
173
What post-processing technique utilizes thin slices and overlapping helically acquired image data to reformat cross sectional anatomy to anatomical surface renderings?
3D surface rendering
174
What is the field of view that covers the area within the gantry from which the raw data is acquired?
Scan Field of View (SFOV)
175
______________ determines the range of CT numbers that occupy the full gray scale on the image monitor. Only the CT numbers within the specified range will be evenly distributed across the gray scale. The gray scale goes from black to bright white. Increasing the window width allows a larger range of CT numbers to be viewed within the gray scale. It will also make the image appear to have less contrast between tissues with similar CT numbers.
Window Width
176
What is the optimal scan slice thickness when imaging all musculoskeletal anatomy?
0.625 mm - 1.25 mm
177
When the scan plane is perpendicular to the subtalar joint and the gantry is tilted towards the patient at around 25 degrees, what is the directly acquired imaging plane?
Oblique Coronal Plane
☑️ To obtain a direct oblique coronal plane on foot/ankle CT exams, the patient should be positioned with knees bent and feet flat on the scan table. The gantry is angled 20-30 degrees perpendicular to the subtalar joint. This will acquire the scan data in a direct oblique coronal plane.
178
A dilated non-opacified appendix with soft tissue stranding commonly represents what diagnosis?
Acite Appendicitis
☑️ Acute Appendicitis can often be diagnosed when the CT images display a dilated and non-contrast opacified appendix. There may also be soft tissue stranding or inflammation around the adjacent tissues. Sometimes an appendicolith may also be present.
179
What method or type of contrast administration may occur if the distal colon is not properly opacified with timed oral contrast agents for a Pelvic CT exam?
Rectal Contrast
180
Which window center and window width would best display a lung window at the viewing console?
C/W -600, 1700
181
The accumulation of gas between the verterbral disks is known as:
Vaccum phenomenon
182
The best quality CT images of the sternum are reformatted in the __________planes.
Coronal only
183
If iodinated contrast is used in scans of the humerus and forearm, the appropriate scan delay time is _______sec.
20-30
184
results from a fracture in the temporal region of the skull with associated tearing of the middle meningeal artery?
Epidural hematoma
185
Where is contrast media introduced for a myelography exam of the spinal canal?
Subarachnoid space
186
What type of drug is Demerol?
Analgesic
187
A(n) _____ artifact is a streak artifact which arises from a high spatial frequency interface between tissues with a great difference in density.
Edge gradient
188
Which of the following would not enhance during the first several minutes of a post-contrast CT study of the neck?
Lymph nodes
189
Which of the following is associated with a bi-phasic study of the liver?
☑️differentiation of lesions with arterial and portal venous blood supplies
☑️two images for each slice position
190
CT x-ray tube arcing can occur because of ______ the x-ray tube.
☑️impurities in the oil outside
| ☑️tungsten gas outside
191
MDCT scanners capable of collecting 64 slices in a single rotation do NOT:
Use filtered back projection as their method of image reconstruction
192
The distance that the table travels between slices is called:
Table Increment
193
Which of the following values for pitch would stretch the x-ray helix the most?
1.5
194
The normally accepted range for BUN is
5 - 25 mg/dl.
195
The pencil thin section of the x-ray fan beam that strikes a single detector is called a:
Ray
196
Which scanning plane is best for evaluating the anatomical relationship between the pituitary and the sella turcica?
Coronal
☑️ Coronal images should be either directly acquired or reconstructed from the helical images using thin slices of about 1-2mm and should extend from the anterior clinoid through the dorsum sella.
197
If an algorithm to correct for the cupping artifact is applied too aggressively to the data for a head image, the _____ of the image would be too bright.
Center
198
The most common catheter size used in CT _____ gauge.
18-22
199
A retrospective reconstruction, in which the reconstruction field-of-view is varied, uses:
CT Raw Data
200
Which of the following provides the best bone window setting for the pelvis?
Window width = 2000, window level = 350
201
Which technology do multi-row detector scanners employ?
Third Generation
202
What is the appropriate care to give to a patient with diabetes?
☑️if IV contrast media is required, use LOCM
☑️if the patient is using Metformin, advise them to resume its use 48 hours after IV contrast administration only after kidney function has been reassessed and determined to be normal
203
What is the cause for the cupping artifact?
The tissues of the body attenuate low energy photons
204
How should the mAs be varied to compensate for an increase in apparent image noise caused by reducing the slice thickness?
Increase mAs
205
The osmolality of plasma is _____ mOsm/kg.
285
206
If there is no overlap or gap between adjacent slices of a CT scan, CTDI _____ MSAD.
Equal
☑️ The CT dose index (CTDI) and the multiple scan average dose(MSAD) are two ways that the patient dose from a multiple slice CT scanner are measured.
207
Tube arcing might cause _____ on the images.
An increase appearance of noise.
208
For a CT scan of the spleen, which of the following is typically used?
Both oral and IV contrast media
209
Which of the following window settings provides the best tissue differentiation of the soft tissues of the supratentorium?
Window width = 100, window level = 30
210
Barium sulfate oral contrast media would be selected instead of iodinated oral contrast media because:
the contrast media stays more dense in the distal GI tract
211
From which of the following can the most diagnostic multi-planar reconstructions be generated?
stacked transverse images from a helical scan
212
Lower osmolar contrast media:
Typically has a higher concentration of particles compared to blood
213
In which direction are streaks from the edge gradient effect oriented?
Parallel to the direction of the sharp density difference interface
214
Platelets are small:
Cell fragments necessary for blood coagulation
215
Tube interscan delay time refers to:
The time between the end of one scan and the start of the next scan during which the tube will cool
216
Which of the following may occur if the patient's arms are placed at their sides during a chest exam if the scan field-of-view is 33 cm?
Beam hardening, beam out of field artifact
217
Which of the following would result if the filter at the aperture of the x-ray tube removed even more low energy w-ray photons?
Beam hardening artifact would decrease
218
Which of the following determinants of CT image quality is responsible for how grainy or speckled a CT image appears?
Noise
219
__________ is the mathematical process used by single-row detectors scanners to reconstruct CT images from raw data
Filtered back projection
220
Which of the following may reduce the out-of-field artifact?
Increasing the scan field-of-view
221
CT numbers _____ would appear black if a window width of 400 and a window level of -100 are used.
Below -300
222
Which of the following is the typical scan delay after the initiation of injection of contrast media for studies of the liver?
65-75 seconds
223
Which of the following would make noise in the image appear less noticeable?
☑️increased mAs
☑️increased slice thickness
☑️increased window widths
224
________ allows helical data to be converted into planer raw data.
Interpolation
225
Iodinated IV contrast agents perfuse normal:
Liber tissues
226
Which of the following could be the dose experienced by the pituitary from a typical CT brain scan?
2 rads
☑️ The typical skin dose, at the point of entry, for a brain scan is approximately 1 to 3 rads. During a brain scan, the dose is relatibely uniform throughout the head due to the size and mmost photons are not absorbed. Also 1 mGy = 0.01 rads
227
Which of the following is a reason to increase the pitch?
☑️a given volume of anatomy can be covered faster
| ☑️a greater volume of anatomy can be covered in a given time
228
On a multi-row detector scanner, a radiation penumbra may be found:
Only on the first and last slices of the slice volume
229
Which of the following is TRUE as the slice thickness is decreased?
Partial volume artifacts and edge gradient artifacts decrease
230
When a contrast agent is injected directly into the joint space it is known as _____ contrast.
Intraarticular
231
Which of the following are possible results of partial voluming?
☑️misleading CT numbers
☑️decreased sharpness of edges
Partial voluming occurs when more than one tissue is contained within a voxel and the attenuation values of the tissues are averaged together to determine the final CT number. It can blur edges between tissues if the edges fall within a voxel.
232
In which of the following studies might cranial nerve XI be visualized?
Soft tissue neck
233
Which of the following is the appropriate range of coverage for a coronal sinus study?
From the dorsum sella to the anterior aspect of the frontal sinus
234
Which of the following would eliminate a ring artifact?
Recalibration of the detector elements
235
______ scanner design was the first to acquire four slices in a single rotation.
Multi-row detector
236
Which of the following is the conversion equation from CT number to Hounsfield unit?
CT number = Hounsfield Unit
237
The field of view for an internal auditory canal scan should be
23cm prospectively/ 10cm retrospectively
238
Proper patient positioning for CT of yhe knee is feet first and supine, with the feet:
Internally rotated
239
A proper IV contrast bolus for a soft tissue scan of the neck is ____cc at ____cc/sec
20,2
240
What tyoe of scout scans should be taken prior to performing craniofacial scans?
Both anterior-posterior and lateral
241
The _______ is/are the smallest of yhe cranial bones.
Lacrimal bones
242
What would eliminate a ring artifact?
Recalibration of the detector elements
243
If the slice thickness is changed from 5mm to 7mm and all other parameters are held constant, _____% more photons will be used in making the slice.
40
☑️As the slice thickness is increased, the number of photons used in making the slice is increased proportionately.
244
The portal venous phase occurs about _____ seconds after the start of the IV contrast injection.
60-90
245
CPR must be administered to a cardiac arrest victim within a maximum of ______minutes before there is a risk of brain damage.
4
246
As the slice thickness increases, partial volume artifacts and wdge gradient artifacts
Decreases
247
Is used to better visualize low contrast resolution.
Narrow window width
248
The CSF is produced in the _________ which originates in the ventricles of the brain.
Choroid plexus
249
________ the window ______ will make the image appear darker so that the bony structures can be evaluated.
Increasing, level
250
A normal pulse rate for infant is _______ BPM.
140
☑️ infant - 100-189
child - 95-110
Adult - 70-100
Athletic Adult - 45-60
251
How many seconds is a tyoical scan delay following the start of injection for helical CT examinations of the pancreas?
50-60 seconds
252
Allows adjacent slices to be overlapped without increasing the dose to the patient
Reconstruction Interval
253
A delay of about ______ seconds after the start of the IV contrast injection should be used for a helical scan of the neck.
35
254
Ring-shaped part of the CT scanner
Gantry
255
What are the twi major components of a CT image system.
Gantry and table
256
Optimal characteristics of detector are:
☑️high detector efficiency - ability of the detector to capture transmitted photons and change them to electonic signals
☑️low, or no, afterglow - defined as a brief, persistent flash of scintillation that must be taken into account and subtracted before inage reconstruction
☑️High scatter suppression
☑️high stability - w/c allow system to be used w/o interruption of frequent calibration
257
Overall detector efficiency is the product of what number of factors?
☑️stopping power of a detector material
☑️scintillator efficiency (in solid state type)
☑️charge collection efficiency (in xenon types)
☑️geometric efficiency
☑️scatter rejection
258
Defined as the amount of space occupied by the detector collimator plates relative to the surface area of the detector
Geometric efficiency
259
During CT perfusion studies, the quantity of blood (in mL) that moves through 100 g of tissue each minute is termed the:
Cerebral blood flow (CBF)
260
Bowel obstruction due to loss of normal contractile motion in an area of intestine is termed:
Ileus
261
The prone position may be used for a postmyelogram CT examination of the lumbar spine in an effort to :
Reduce metrizamide pooling
262
The stanford type A desecting aneurysm affects which portion of the aorta?
Ascending Aorta
* Stanford type B dissecting aneurysms affect the descending aorta
263
The firm, outer portion of each intervertebral disc is called the:
Annolus Fibrosus
264
Surgical resection of the pancreas and duodenum for treatment of pancreatic carcinoma
Whipple Procedure
265
The epithelial lining of the urinary tract called the:
Urothelium
266
Vital components of a CT urogram (CT-IVP) protocol include:
Thin section excretory phase imaging of the entire urinary tract
Volume-rendered 3D and maximum intensity projection (MIP) imaging of the urinary tract
267
The brightness of the image is adjusted via _________
Window level
268
The contrast of the image is adjusted via the ________
Window width
269
In which of the following cranial nerves would an acoustic neuroma be found
Eighth
270
Which of the following interscan delays would be used for a dynamic CT study of the chest
4s
271
Which of the following would increase the noise of a CT image
Decrease aperture size
272
The major disadvantage of the back projection method of image reconstruction is the appearance of the
Star artifact
273
The most effective method of reducing involuntary motion on a CT image is through
Reduce scan times
274
Which of the following matrices provides the greatest spatial resolution
1024x1024
275
The spatial resolution of a CT scanner is usually expressed as
Lp/cm
276
As the attenuation of a volume of tissue decreases, the transmitted intensity of a CT beam
Increases
