CT Registry Review May 13,2010
Registry review-monica
Questions and Answers
- 1.
Tungsten is used as the target material on the tube's anode because it has a _____ atomic number and a ______ melting point.
- A.
Low, high
- B.
High, low
- C.
Low, low
- D.
High, high
Correct Answer
D. High, highExplanation
Tungsten is used as the target material on the tube's anode because it has a high atomic number and a high melting point. The high atomic number of tungsten allows it to efficiently produce X-rays when bombarded with high-energy electrons. Additionally, the high melting point of tungsten ensures that it can withstand the heat generated during the X-ray production process without melting or deforming.Rate this question:
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- 2.
_________________ scanner design was the first to acquire four slices in the single rotation.
- A.
Second-generation
- B.
Third-generation
- C.
Multi-row detector
- D.
Continuous rotation
Correct Answer
C. Multi-row detectorExplanation
The multi-row detector scanner design was the first to acquire four slices in a single rotation. This means that the scanner was able to capture multiple images or slices of the body in just one rotation, improving efficiency and reducing scanning time. This advancement in technology allowed for faster and more accurate diagnoses, making it a significant milestone in the evolution of CT scanners.Rate this question:
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- 3.
The enormous heat that builds up in the CT tube is caused by the:
- A.
Intensity of the x-rays emitted from the tube
- B.
Electron beam between the cathode and the anode in the tube
- C.
X-ray filter in the tube which absorbs the lower energy photons
- D.
Collision of the electron beam with the tungsten target on the tube anode
Correct Answer
D. Collision of the electron beam with the tungsten target on the tube anodeExplanation
The vast majority of this energy is emitted as heat while a relatively small amount of this energy is converted to x-ray production.Rate this question:
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- 4.
The number of electrons that from from the cathode to the anode in the tube is controlled by the:
- A.
Anode target
- B.
Collimation
- C.
MA
- D.
KV
Correct Answer
C. MAExplanation
The number of electrons that flow from the cathode to the anode in the tube is controlled by the mA (milliamperage) setting. mA determines the amount of current flowing through the tube, which directly affects the number of electrons emitted from the cathode. Increasing the mA setting will result in more electrons being emitted, while decreasing the mA setting will reduce the number of electrons. Therefore, mA is responsible for controlling the electron flow in the tube.Rate this question:
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- 5.
The slip ring on continuous rotation CT scanners: 1. prevent the high voltage cable from winding up 2. allows the exam to commence more rapidly 3. eliminates the need for the reversal of gantry frame rotation
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1,2,&3
Correct Answer
D. 1,2,&3Explanation
The slip ring on continuous rotation CT scanners serves multiple purposes. Firstly, it prevents the high voltage cable from winding up, which could lead to damage or tangling. Secondly, it allows the exam to commence more rapidly by providing a continuous flow of power and data transmission without the need for interruptions or pauses. Lastly, it eliminates the need for the reversal of gantry frame rotation, as the slip ring enables the transfer of power and data between the stationary and rotating parts of the scanner. Therefore, all three options - 1, 2, and 3 - are correct.Rate this question:
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- 6.
Which of the following is NOT a part of the CT tube?
- A.
Tungsten target
- B.
Collimator
- C.
Rotating anode
- D.
Filament
Correct Answer
B. CollimatorExplanation
A collimator is not a part of the CT tube. The CT tube consists of a tungsten target, rotating anode, and a filament. The tungsten target is where the x-rays are produced, the rotating anode helps dissipate heat generated during the x-ray production, and the filament is responsible for heating the target. However, a collimator is a separate component that is used to narrow down and shape the x-ray beam before it reaches the patient. It is not directly part of the CT tube itself.Rate this question:
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- 7.
Which of the following are NOT commonly used on today's commercially available CT scanners? 1. xenon detectors 2. fourth-generation technology 3. continuous rotation technology
- A.
1 only
- B.
1 & 2
- C.
2 & 3
- D.
1, 2, & 3
Correct Answer
B. 1 & 2Explanation
Xenon detectors and fourth-generation technology are NOT commonly used on today's commercially available CT scanners.Rate this question:
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- 8.
Which system component converts the projection attenuation data into the proper digital form for the array processor?
- A.
Detector
- B.
Photodiode
- C.
Analog-to-digital converter
- D.
Host computer
Correct Answer
C. Analog-to-digital converterExplanation
The analog-to-digital converter is the system component that converts the projection attenuation data into the proper digital form for the array processor. This conversion is necessary because the array processor can only process digital data, while the projection attenuation data is in analog form. The analog-to-digital converter takes the analog signal from the detector or photodiode and converts it into a digital signal that can be processed by the array processor.Rate this question:
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- 9.
X-ray photons are produced by a fast-moving electron: 1. colliding with an atomic nucleus 2. passing close to an atomic nucleus 3. colliding with an electron within an atom and ejecting it
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, & 3
Correct Answer
D. 1, 2, & 3Explanation
X-ray photons are produced by a fast-moving electron through all of the given processes. When the electron collides with an atomic nucleus (option 1), it can produce X-ray photons. Similarly, when the electron passes close to an atomic nucleus (option 2), it can also produce X-ray photons. Additionally, when the electron collides with an electron within an atom and ejects it (option 3), X-ray photons can be generated. Therefore, all three options are correct and contribute to the production of X-ray photons.Rate this question:
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- 10.
Which of the following is TRUE regarding solid state detectors? 1. x-ray photons cause the detectors to generate a flash of light 2. they are the detector type used on most CT scanners today 3. they can be used in both third-generation and fourth-generation CT systems
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, & 3
Correct Answer
D. 1, 2, & 3Explanation
Solid state detectors are able to generate a flash of light when exposed to x-ray photons, making statement 1 true. These detectors are commonly used in most CT scanners today, making statement 2 true. Additionally, solid state detectors can be utilized in both third-generation and fourth-generation CT systems, making statement 3 true. Therefore, the correct answer is 1, 2, & 3.Rate this question:
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- 11.
CT is commonly referred to as all of the following names EXCEPT:
- A.
Computerized axial tomography
- B.
Digital subtraction angiography
- C.
CAT-scan
- D.
Computed tomography
Correct Answer
B. Digital subtraction angiographyExplanation
Digital subtraction angiography (DSA) is a medical imaging technique used to visualize blood vessels. It involves the injection of contrast material into the blood vessels and the use of digital image processing to subtract the background structures, resulting in a clearer visualization of the blood vessels. CT, CAT-scan, and computed tomography are all different names for the same imaging technique, which uses X-rays and computer processing to create detailed cross-sectional images of the body. Therefore, the correct answer is digital subtraction angiography, as it is not a commonly used name for CT.Rate this question:
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- 12.
What control does the operator have over the x-rays in a CT exam
- A.
The temperature and color of the x-rays can be tuned
- B.
The energy level and the quantity of x-rays can be selected
- C.
The volume and tone of the x-rays can be dialed
- D.
The phase and frequency of the x-rays can be adjusted
Correct Answer
B. The energy level and the quantity of x-rays can be selectedExplanation
The operator has control over the energy level and the quantity of x-rays in a CT exam. This means that they can adjust the strength and amount of x-rays used during the exam, allowing for customization based on the specific needs of each patient.Rate this question:
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- 13.
Which of the following statements is TRUE? 1. kV is the voltage potential between the tube cathode and anode while mA ultimately controls the filament current and, thus, the temperature of the cathode filament. 2. kV controls the energy level of the x-ray photons and mA controls the number of x-ray photons emitted from the tube 3. although the kV and the mA affect the operation of the CT x-ray tube, the two paramanters have no bearing on the image quality
- A.
1 only
- B.
2 only
- C.
1 & 2
- D.
2 & 3
Correct Answer
C. 1 & 2Explanation
The correct answer is 1 & 2 because statement 1 correctly states that kV is the voltage potential between the tube cathode and anode while mA controls the filament current and temperature of the cathode filament. Statement 2 is also true as it states that kV controls the energy level of the x-ray photons and mA controls the number of x-ray photons emitted from the tube. Both statements accurately describe the roles of kV and mA in the operation of the x-ray tube.Rate this question:
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- 14.
Which of the following does NOT affect the quantity of x-rays that completely penetrates the patient? 1. the distance that the x-ray photons must travel on their course though the patient's body 2. the molecular composition of the tissues though with the x-ray photons pass 3. the type of detector material used
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, & 3
Correct Answer
D. 1, 2, & 3Explanation
The quantity of x-rays that completely penetrates the patient is not affected by the distance that the x-ray photons must travel through the patient's body, the molecular composition of the tissues through which the x-ray photons pass, or the type of detector material used.Rate this question:
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- 15.
___________made helical imaging possible.
- A.
Multi-row detector scanners
- B.
The introduction of second-generation technology
- C.
The introduction of fourth-generation technology
- D.
Continuous rotation scanners
Correct Answer
D. Continuous rotation scannersExplanation
Continuous rotation scanners made helical imaging possible. Helical imaging is a technique in computed tomography (CT) where the X-ray tube and detector continuously rotate around the patient, while the patient is moved through the scanner. This allows for the acquisition of volumetric data without the need for multiple stops and starts. Continuous rotation scanners provide a more efficient and faster scanning process, resulting in improved image quality and reduced patient discomfort. The introduction of continuous rotation scanners revolutionized CT imaging and made helical imaging a standard technique in modern CT scanners.Rate this question:
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- 16.
Which of the following statements is FALSE regarding the collection of CT date?
- A.
Long scan times are more desirable because they average out motion artifacts
- B.
The reconstruction process used to create the image occurs in the array processor
- C.
To collect the complete set of CT data, x-rays mus be passed through the body at many different angles
- D.
The detectors measure x-rays which completely penetrate the patient
Correct Answer
C. To collect the complete set of CT data, x-rays mus be passed through the body at many different angles -
- 17.
Which of the following is a component NOT normally located in the gantry of a modern CT system?
- A.
Pre-patient collimators
- B.
Solid-state detectors
- C.
Array processor
- D.
X-ray tube
Correct Answer
C. Array processorExplanation
The array processor is not normally located in the gantry of a modern CT system. The gantry typically contains components such as the pre-patient collimators, solid-state detectors, and x-ray tube. The pre-patient collimators help shape and control the X-ray beam, the solid-state detectors capture the X-ray signals and convert them into electrical signals, and the X-ray tube generates the X-ray beam. The array processor, on the other hand, is usually located outside the gantry and is responsible for processing the captured data to create the final CT images.Rate this question:
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- 18.
X-rays are used in CT because:
- A.
They are easily produced by the high frequency generator
- B.
They are less harmful than the heating effects of microwave radiation
- C.
They penetrate the body according to specific attenuation characteristics of each tissue
- D.
The FDA imposes no limit on the dose of the patient
Correct Answer
C. They penetrate the body according to specific attenuation characteristics of each tissueExplanation
X-rays are used in CT because they have the ability to penetrate the body based on the specific attenuation characteristics of each tissue. This means that different tissues in the body absorb and scatter X-rays to different extents, allowing for detailed imaging of internal structures. The other options provided in the question do not accurately explain why X-rays are used in CT.Rate this question:
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- 19.
X-rays are produced whenever fast-moving electrons collide with any form of matte because: 1. the electron splits into two x-ray photons of equal energy upon impact with the matter 2. the electron loses kinetic energy which is converted into the emission of an x-ray phone 3. the electron converts the electron it collides with into an x-ray photon
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, & 3
Correct Answer
D. 1, 2, & 3Explanation
When fast-moving electrons collide with any form of matter, three things happen: 1) The electron splits into two x-ray photons of equal energy upon impact with the matter, 2) The electron loses kinetic energy which is converted into the emission of an x-ray photon, and 3) The electron converts the electron it collides with into an x-ray photon. Therefore, all three statements (1, 2, and 3) are correct explanations for why X-rays are produced when fast-moving electrons collide with matter.Rate this question:
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- 20.
Bremsstrahlung radiation does NOT include which type of electron activity? 1. collision between an incoming electron and the nucleus of the target atom. 2. collision between an incoming electron and an electron in an inner shell of the target atom. 3. slowing down of an incoming electron due to the effect of passing close to the positive charge of the nucleus of the target atom.
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
B. 2 onlyExplanation
Bremsstrahlung radiation is the electromagnetic radiation emitted when a charged particle, such as an electron, is accelerated or decelerated by the electric field of another charged particle, such as the nucleus of an atom. This radiation is produced when an incoming electron collides with an electron in an inner shell of the target atom, causing the latter to be ejected from its orbit. Therefore, the correct answer is 2 only, as it states that bremsstrahlung radiation does not include the collision between an incoming electron and an electron in an inner shell of the target atom.Rate this question:
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- 21.
The mA determines the :
- A.
Quantity of x-ray photons
- B.
Coefficient of attenuation
- C.
Slice thickness
- D.
Energy level of the x-ray photons
Correct Answer
A. Quantity of x-ray photonsExplanation
The mA (milliamperage) determines the quantity of x-ray photons produced during an X-ray examination. The higher the mA setting, the more photons are produced, resulting in a higher quantity of X-rays. This is because mA controls the amount of electrical current passing through the X-ray tube, which in turn affects the number of X-ray photons generated. Therefore, the correct answer is the quantity of x-ray photons.Rate this question:
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- 22.
Increased __________ will increase the likelihood that a given x-ray will penetrate a material. 1. kV 2. mA 3. exposure time
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
A. 1 onlyExplanation
Increasing the kilovolt (kV) will increase the likelihood that a given x-ray will penetrate a material. This is because the kilovolt determines the energy of the x-ray beam. Higher energy x-rays have more penetrating power and can pass through materials more easily.Rate this question:
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- 23.
Collimation:
- A.
Is accomplished by electrically blocking x-rays
- B.
Affects the scan time
- C.
Limits the low energy x-ray photons and passes the high energy photons
- D.
Is accomplished by physically blocking x-rays
Correct Answer
D. Is accomplished by physically blocking x-raysExplanation
Collimation is a process that involves physically blocking x-rays. It is not achieved through electrical means or by affecting the scan time. Instead, collimation limits the low energy x-ray photons and allows only the high energy photons to pass through. This helps to improve the quality and accuracy of the imaging by reducing scatter radiation and enhancing the clarity of the image.Rate this question:
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- 24.
Scatter radiation is caused by:
- A.
Miscalibrated detector
- B.
X-rays generated spontaneously in the ambient atmosphere
- C.
Deflections from the original trajectory of an x-ray photon through the patient
- D.
Improper patient positioning
Correct Answer
C. Deflections from the original trajectory of an x-ray photon through the patientExplanation
Scatter radiation is caused by deflections from the original trajectory of an x-ray photon through the patient. When an x-ray beam passes through the patient's body, it interacts with the tissues and can change direction, resulting in scatter radiation. This occurs when the x-ray photons collide with atoms in the patient's body and change their path. Scatter radiation is undesirable as it can reduce image quality and increase radiation dose to the patient and medical staff. Proper shielding and positioning techniques are used to minimize scatter radiation.Rate this question:
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- 25.
Which technology do multi-row detector scanners employ?
- A.
Second-generation
- B.
Third-generation
- C.
Fourth-generation
- D.
First-generation
Correct Answer
B. Third-generationExplanation
Multi-row detector scanners employ third-generation technology. This technology refers to the use of multiple rows of detectors in the scanner, allowing for faster and more accurate imaging. Compared to first and second-generation scanners, third-generation scanners provide better image quality and reduced radiation exposure. Fourth-generation scanners, on the other hand, use a different technology called stationary detectors, which are not applicable to multi-row detector scanners. Therefore, the correct answer is third-generation.Rate this question:
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- 26.
Which of the following is NOT a function of a PACS system?
- A.
Reconstruction of the image from the raw data
- B.
Long term data storage
- C.
Digital distribution of images
- D.
Image display for the radiologists
Correct Answer
A. Reconstruction of the image from the raw dataExplanation
A PACS system, or Picture Archiving and Communication System, is primarily used for the storage, retrieval, distribution, and display of medical images. It allows for long term data storage, digital distribution of images, and image display for radiologists. However, the reconstruction of the image from the raw data is not a function of a PACS system. This process typically occurs before the image is stored in the system and involves converting the raw data captured by the imaging modality into a visual image that can be interpreted by radiologists.Rate this question:
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- 27.
Which of the following is TRUE regarding multi-row detector CT scanners? 1. the size of the detector arrays along the z-direction may be different. 2. the attenuation information from adjacent detector arrays may be added together to generate thicker slices. 3. all of the detector arrays may or may not be used.
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
D. 1, 2, and 3Explanation
Multi-row detector CT scanners have the capability to vary the size of the detector arrays along the z-direction, which means that the size of the detectors can differ. Additionally, these scanners can combine the attenuation information from adjacent detector arrays to generate thicker slices, allowing for better image quality. Lastly, multi-row detector CT scanners have the flexibility to choose whether to use all of the detector arrays or not, depending on the specific imaging requirements. Therefore, all three statements are true regarding multi-row detector CT scanners.Rate this question:
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- 28.
Which of the following is FALSE regarding CT systems? 1. they are limited to non-oblique transverse scanning. 2. they cannot generate a straight coronal or sagital image. 3. they have no moving parts.
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
D. 1, 2, and 3Explanation
CT systems are not limited to non-oblique transverse scanning, as they can also perform oblique scanning. They can generate straight coronal or sagittal images, so statement 2 is false. Additionally, CT systems do have moving parts, such as the gantry and the table, so statement 3 is also false. Therefore, the correct answer is 1, 2, and 3.Rate this question:
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- 29.
Most of the commands from the technologist are received by the:
- A.
Array processor
- B.
Operator's console
- C.
Host computer
- D.
Amplifier
Correct Answer
B. Operator's consoleExplanation
The correct answer is the operator's console. The operator's console is where most of the commands from the technologist are received. This is the central control point where the technologist can input commands and monitor the system. It allows the technologist to interact with the equipment and make necessary adjustments or changes as needed. The operator's console is an essential component in managing and controlling the system efficiently.Rate this question:
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- 30.
The operator's console may include: 1. monitor 2. keyboard 3. graphic input device
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
D. 1, 2, and 3Explanation
The operator's console may include a monitor, keyboard, and a graphic input device. These components are commonly found in an operator's console as they are essential for monitoring and controlling various systems or processes. The monitor allows the operator to view important information or data, the keyboard enables input and interaction with the system, and the graphic input device can be used for tasks such as drawing or manipulating graphical elements. Therefore, all three options - 1, 2, and 3 - are correct.Rate this question:
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- 31.
Which of the following CT scanner designs does NOT use an x-ray tube?
- A.
First-generation CT
- B.
PET/CT
- C.
Electron beam CT
- D.
MDCT
Correct Answer
C. Electron beam CTExplanation
The electron beam CT does not use an x-ray tube. Instead, it uses an electron gun to produce a high-energy electron beam that is focused onto a tungsten target. This target then emits x-rays, which are used for imaging. In contrast, the other options mentioned - first-generation CT, PET/CT, and MDCT - all use an x-ray tube as part of their design.Rate this question:
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- 32.
Tube interscan delay time refers to:
- A.
The time between the end of one scan and the start of the next scan during which the tube will cool
- B.
A quality assurance text performed daily by the technologist
- C.
The time required for the tube to make a complete 360 revolution about the gantry
- D.
The length of time required for the production of photons to begin after applying the voltage to the tube
Correct Answer
A. The time between the end of one scan and the start of the next scan during which the tube will coolExplanation
The 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. This is important because the X-ray tube can generate a significant amount of heat during a scan, and it needs time to cool down before the next scan can be performed. If the tube is not given enough time to cool, it can overheat and potentially malfunction, leading to poor image quality or damage to the equipment. Therefore, it is necessary to have a specific delay time to ensure the proper functioning and longevity of the X-ray tube.Rate this question:
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- 33.
On a signle-row detector scanner, collimation: 1. controls the slice thickness 2. minimizes the x-ray dose to the patient 3. reduces the detection of scatter radiation
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
D. 1, 2, and 3Explanation
Collimation on a single-row detector scanner serves multiple purposes. Firstly, it controls the slice thickness, allowing for the adjustment of the width of the X-ray beam and consequently influencing the thickness of the image slices produced. Secondly, collimation helps minimize the X-ray dose to the patient by limiting the amount of radiation exposure to the areas outside the targeted region. Lastly, it reduces the detection of scatter radiation, which can lead to image degradation and inaccuracies. Therefore, all three options, 1, 2, and 3, are correct.Rate this question:
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- 34.
The main purpose of the detector is to:
- A.
Provide additional collimation in order to reduce scatter
- B.
Limit the x-ray dose to the patient
- C.
Capture x-ray photons and convert them to a measurable signal
- D.
Amplify the measured signal
Correct Answer
C. Capture x-ray photons and convert them to a measurable signalExplanation
The detector's main purpose is to capture x-ray photons and convert them to a measurable signal. This is important because it allows for the creation of digital images that can be analyzed and interpreted by medical professionals. By capturing the x-ray photons, the detector enables the visualization of internal structures and abnormalities in the patient's body. The conversion of the photons into a measurable signal ensures that the information can be accurately recorded and analyzed.Rate this question:
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- 35.
In order for an x-ray photon to be measured it must: 1. enter the detector chamber 2. be absorbed by the detector material 3. be converted to a measurable event
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2 and 3
Correct Answer
C. 3 onlyExplanation
An x-ray photon can only be measured if it is converted to a measurable event. This means that it needs to interact with the detector material and be absorbed by it, causing a measurable signal. Entering the detector chamber alone is not sufficient for measurement. Therefore, the correct answer is 3 only.Rate this question:
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- 36.
The patient table:
- A.
May move continuously during the scan
- B.
Can never be positioned automatically by software due to safety precautions
- C.
Remains stationary throughout the patient exam once it is initially positioned
- D.
Only moves after each slice is completed
Correct Answer
D. Only moves after each slice is completedExplanation
The patient table remains stationary throughout the patient exam once it is initially positioned. This means that once the patient is properly positioned on the table, it will not move during the scan. It will only move after each slice is completed, allowing for the next slice to be captured. This movement is necessary to ensure that all required areas are scanned and to maintain the accuracy of the imaging process.Rate this question:
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- 37.
Which of the following statements is FALSE regarding occurrences after an x-ray photon penetrates the detector aperture? 1. the photon can pass through the detector unmeasured 2. the photon is converted completely into an electron 3. the measured signal is enhanced by an amplifier
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
A. 1 onlyExplanation
After an x-ray photon penetrates the detector aperture, it can pass through the detector unmeasured. This means that the photon may not interact with the detector and therefore not be detected or measured. This is in contrast to statement 2, which suggests that the photon is converted completely into an electron upon interaction with the detector. Additionally, statement 3 is also false as the measured signal is not enhanced by an amplifier. Therefore, the only false statement is 1, which states that the photon can pass through the detector unmeasured.Rate this question:
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- 38.
CT images can be directly scanned in planes other than transverse by: 1. orienting the patient's body part so that it is not perpendicular to the x-ray beam. 2. tilting the gantry 3. changing the angle that the x-ray beam leaves the tube.
- A.
1 only
- B.
1 & 2
- C.
2 & 3
- D.
1, 2, and 3
Correct Answer
B. 1 & 2Explanation
CT images can be directly scanned in planes other than transverse by orienting the patient's body part so that it is not perpendicular to the x-ray beam and tilting the gantry. By adjusting the position of the patient's body part and the gantry, the CT scanner can capture images in different planes, such as sagittal or coronal, instead of just transverse. This allows for a more comprehensive evaluation of the anatomy and enhances the diagnostic capabilities of the CT scan.Rate this question:
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- 39.
The CT x-ray tube rotates around the patient to: 1. keep the tube cool 2. generate projection vies at different angles 3. minimize the x-ray dose administered to the patient
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, and 3
Correct Answer
B. 2 onlyExplanation
The CT x-ray tube rotates around the patient to generate projection views at different angles. This allows for a comprehensive and detailed image of the patient's anatomy to be created. By capturing images from different angles, the CT scan provides a three-dimensional representation of the patient's body, aiding in the diagnosis and treatment of various medical conditions. The rotation of the x-ray tube also helps to minimize artifacts and improve image quality.Rate this question:
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- 40.
The cathode filament:
- A.
Helps determine the size of the focal spot
- B.
Lights up the tube so it can be seviced by an engineer
- C.
Releases the x-ray photons
- D.
Focuses x-rays onto the anode target
Correct Answer
A. Helps determine the size of the focal spotExplanation
The cathode filament helps determine the size of the focal spot. The focal spot size is an important characteristic of an x-ray tube as it directly affects the image quality. The filament heats up and emits electrons, which are then accelerated towards the anode target. The size of the filament and the current passing through it determine the number of electrons emitted, which in turn affects the size of the focal spot. A smaller filament and lower current result in a smaller focal spot, leading to improved spatial resolution in the x-ray image.Rate this question:
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- 41.
Using _________ reconstruction filter would decrease the appearance of noise in a CT image1. no2. a sharp3 a smooth
- A.
1 only
- B.
2 only
- C.
2&3
- D.
3 only
Correct Answer
D. 3 onlyExplanation
Using a smooth reconstruction filter would decrease the appearance of noise in a CT image. This is because a smooth filter helps to average out the noise and create a more uniform image. A sharp filter, on the other hand, would enhance the noise and make it more prominent. Therefore, option 3 only is the correct answer.Rate this question:
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- 42.
A________ scan uses only a single projection1. conventional, or serial2. helical3. localizer
- A.
1only
- B.
2 only
- C.
3 only
- D.
1,2, and 3
Correct Answer
C. 3 onlyExplanation
The correct answer is 3 only. A localizer scan uses only a single projection. This means that it captures a single image or slice of the body at a time, allowing for a more focused and localized view. In contrast, a conventional or serial scan captures multiple projections or slices in a sequential manner, while a helical scan captures a continuous spiral of images or slices. Therefore, only a localizer scan uses a single projection.Rate this question:
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- 43.
Which of the following statements is FALSE regarding 3D SSD?
- A.
Helical image data is well suited for 3D SSD because there is minimal misregistration or gaps
- B.
The volume data, from which the 3D SSD is generated, is created by combining transverse, sagittal, and coronal reconstructions
- C.
The tissure surface may be selected by using a threshold value equal to the tissue's CT number
- D.
Patient motion during the scan is detrimental to the quality of the 3D images
Correct Answer
B. The volume data, from which the 3D SSD is generated, is created by combining transverse, sagittal, and coronal reconstructionsExplanation
The correct answer is that the volume data, from which the 3D SSD is generated, is not created by combining transverse, sagittal, and coronal reconstructions. This statement is false because the volume data for 3D SSD is actually created by stacking multiple 2D slices together, rather than combining different types of reconstructions.Rate this question:
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- 44.
Which type(s) of storage media may hold CT image data1. internal hard disk 2. CD3. re-writable optical disk
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1,2 and 3
Correct Answer
D. 1,2 and 3Explanation
CT image data can be stored on internal hard disks, CDs, and re-writable optical disks. Internal hard disks are commonly used for storing large amounts of data, including CT image data. CDs can also be used as a storage medium for CT image data, providing a portable and easily accessible option. Re-writable optical disks offer the advantage of being able to write and rewrite data, making them suitable for storing and updating CT image data. Therefore, all three options, 1, 2, and 3, are correct.Rate this question:
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- 45.
______________ may have to be edited from the data set to get a diagnostic MIP of a CTA exam.
- A.
Iodinated contrast media
- B.
Vessels of interest
- C.
Air
- D.
Bones
Correct Answer
D. BonesExplanation
Bones may have to be edited from the data set to get a diagnostic MIP of a CTA exam. This is because bones can obstruct the visualization of blood vessels and other structures of interest in the scan. By editing out the bones from the data set, a maximum intensity projection (MIP) can be created that focuses solely on the vessels of interest, allowing for a clearer and more accurate diagnostic assessment.Rate this question:
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- 46.
Which of the following is NOT an advantage of a helical study compared to a conventional, serial CT study?
- A.
Minimal anatomical misregistration sometimes caused by inconsistent breath-holding
- B.
Shorter total exam time
- C.
Can retrospectively reconstruct a slice at any arbitrary position
- D.
Offers the best image quality for a brain exam
Correct Answer
D. Offers the best image quality for a brain examExplanation
A helical study does not offer the best image quality for a brain exam. Although a helical study has advantages such as minimal anatomical misregistration, shorter exam time, and the ability to reconstruct a slice at any position, it does not necessarily provide the best image quality specifically for a brain exam. Other imaging techniques or studies may be more suitable for obtaining high-quality brain images.Rate this question:
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- 47.
Which of the following utilizes convolution?1. 3D SSD2. fourier transform3. filtered back projection
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1,2 and 3
Correct Answer
C. 3 onlyExplanation
Filtered back projection is the only option that utilizes convolution. Convolution is a mathematical operation that combines two functions to produce a third function. In the case of filtered back projection, it is used to reconstruct an image from its projections. Fourier transform is a mathematical technique used for signal processing and frequency analysis, while 3D SSD (Single Shot MultiBox Detector) is an object detection algorithm that does not directly involve convolution.Rate this question:
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- 48.
In which technique are tissues other than the surface of a structure excluded by setting a threshold value and eliminating pixels above or below that threshold?
- A.
Volume rendering
- B.
Multi-planar reconstruction
- C.
Maximum intensity projection
- D.
3D shaded surface display
Correct Answer
D. 3D shaded surface displayExplanation
In 3D shaded surface display technique, tissues other than the surface of a structure are excluded by setting a threshold value and eliminating pixels above or below that threshold. This technique creates a three-dimensional representation of the object, highlighting the surface details while disregarding the internal structures. It is commonly used in medical imaging to visualize anatomical structures and can provide a clear and realistic view of the surface of the object of interest.Rate this question:
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- 49.
From which of the following can the most diagnostic multiplanar reconstructions be generated?1. stacked transverse images from a helical scan2. stacked transverse images from a conventional, serial scan3. stacked localizer images
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, & 3
Correct Answer
A. 1 onlyExplanation
Stacked transverse images from a helical scan can generate the most diagnostic multiplanar reconstructions because a helical scan captures continuous data along the z-axis, allowing for reconstructions in multiple planes. This means that the images can be reconstructed in sagittal, coronal, and oblique planes, providing a more comprehensive view of the anatomy. On the other hand, stacked transverse images from a conventional, serial scan and stacked localizer images may not capture continuous data along the z-axis, limiting the ability to generate accurate multiplanar reconstructions.Rate this question:
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- 50.
The actual attenuation data measured by the detectors from all projections during a scan is contained in CT _______ data.1. image2. convolved3. raw
- A.
1 only
- B.
2 only
- C.
3 only
- D.
1, 2, & 3
Correct Answer
C. 3 onlyExplanation
The correct answer is 3 only. In CT scans, the actual attenuation data measured by the detectors from all projections is contained in the raw data. This raw data is then processed to generate images using techniques such as convolution. Therefore, option 1 (image) and option 2 (convolved) are incorrect as they refer to processed data rather than the original raw data.Rate this question:
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