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In an ionization chamber used for radiation detection, if insufficient voltage is applied to the electrodes, which of the following will occur?
In an ionization chamber used for radiation detection, if insufficient voltage is applied to the electrodes, which of the following will occur?
The negative electrode of an X-ray tube is always called the:
The negative electrode of an X-ray tube is always called the:
The focal spot of the X-ray tube is located:
The focal spot of the X-ray tube is located:
The reason the focal spot of the X-ray tube is kept small is to:
The reason the focal spot of the X-ray tube is kept small is to:
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Which of the following tests is the most sensitive for detecting metastatic deposits?
Which of the following tests is the most sensitive for detecting metastatic deposits?
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Diagnosis of aortic calcification is done by fluoroscopy by observing:
Diagnosis of aortic calcification is done by fluoroscopy by observing:
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What is the principal disadvantage of third-generation CT scanners?
What is the principal disadvantage of third-generation CT scanners?
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The reduction in _____ was the principal advantage of the second-generation CT scanners.
The reduction in _____ was the principal advantage of the second-generation CT scanners.
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The first generation of computed tomography used _____ detector(s).
The first generation of computed tomography used _____ detector(s).
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Each pixel of information in the CT image contains numerical information in _____ units.
Each pixel of information in the CT image contains numerical information in _____ units.
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Each sweep of the source-detector around the body during CT is called a:
Each sweep of the source-detector around the body during CT is called a:
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The new development in the fourth-generation CT scanner is the:
The new development in the fourth-generation CT scanner is the:
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Each CT projection records variations in:
Each CT projection records variations in:
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CT scanners operate on _____ voltage generation.
CT scanners operate on _____ voltage generation.
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The _____ generation of CT scanners was the first to have the fan beam transect the entire patient at all times.
The _____ generation of CT scanners was the first to have the fan beam transect the entire patient at all times.
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If each detector was 1.25 mm long and the scanner had 16 rows of detectors, the z-axis coverage (slab thickness) per gantry rotation would total ______ mm.
If each detector was 1.25 mm long and the scanner had 16 rows of detectors, the z-axis coverage (slab thickness) per gantry rotation would total ______ mm.
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In a multiple-row detector CT scanner, how does the beam pitch relate to the collimator pitch?
In a multiple-row detector CT scanner, how does the beam pitch relate to the collimator pitch?
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The Dual Source CT (DSCT) equipped with two data measurement systems, makes it possible to double the resolution compared with a single source CT and _____ the speed of data acquisition.
The Dual Source CT (DSCT) equipped with two data measurement systems, makes it possible to double the resolution compared with a single source CT and _____ the speed of data acquisition.
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With Dual Source mode, each consisting of one X-ray tube and one corresponding detector array oriented in the gantry with an angular offset of _____ degrees.
With Dual Source mode, each consisting of one X-ray tube and one corresponding detector array oriented in the gantry with an angular offset of _____ degrees.
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The degree that material will attenuate the X-ray beam is dependent on tissue composition and photon energy level and how closely it exceeds the _____ of the material.
The degree that material will attenuate the X-ray beam is dependent on tissue composition and photon energy level and how closely it exceeds the _____ of the material.
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The purpose of the imaging system is to:
The purpose of the imaging system is to:
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The abbreviation of data acquisition system is _____.
The abbreviation of data acquisition system is _____.
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What are the advantages of Straton X-ray tubes?
What are the advantages of Straton X-ray tubes?
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Straton X-ray tubes can be used in:
Straton X-ray tubes can be used in:
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The purpose of filtration is to:
The purpose of filtration is to:
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The advantages of Straton X-ray tubes can be used in:
The advantages of Straton X-ray tubes can be used in:
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Straton X-ray tubes for increasing lengths of anatomic coverage use:
Straton X-ray tubes for increasing lengths of anatomic coverage use:
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“Bowtie” filters are usually made of Teflon, which is:
“Bowtie” filters are usually made of Teflon, which is:
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Overbeaming refers to X-ray beams being slightly wider than the detector, which means:
Overbeaming refers to X-ray beams being slightly wider than the detector, which means:
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Overscanning refers to exposure of the patient outside the imaged range, which occurs for spiral CT with:
Overscanning refers to exposure of the patient outside the imaged range, which occurs for spiral CT with:
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The problems of overscanning and overbeaming can be solved using a technique called:
The problems of overscanning and overbeaming can be solved using a technique called:
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CT detectors capture the radiation beam from the patient and convert it into:
CT detectors capture the radiation beam from the patient and convert it into:
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Absorption efficiency refers to the number of photons absorbed by the detector and depends on:
Absorption efficiency refers to the number of photons absorbed by the detector and depends on:
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Conversion efficiency refers to the ability to accurately:
Conversion efficiency refers to the ability to accurately:
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Efficiency refers to the ability to _____ and convert X-ray photons to electrical signals.
Efficiency refers to the ability to _____ and convert X-ray photons to electrical signals.
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The speed with which the detector can detect an X-ray event and recover to detect another event is called:
The speed with which the detector can detect an X-ray event and recover to detect another event is called:
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Scintillation detectors (luminescent materials) convert:
Scintillation detectors (luminescent materials) convert:
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Study Notes
Ionization Chamber and Radiation Detection
- If insufficient voltage is applied to electrodes in an ionization chamber, ions may recombine before reaching electrodes, preventing proper current flow.
- Insufficient Voltage: Ions may not properly adhere to electrodes.
- No current flow: Insufficient voltage may prevent current flow within the circuit.
- Radiation won't ionize the gas: Insufficient voltage may prevent ionization.
- Ions recombine: Created ions may recombine before reaching the electrodes if voltage is insufficient.
X-Ray Tube Components
- Negative electrode: The cathode in an X-ray tube.
- Focal spot location: Located at cathode or at anode, but typically kept small at midpoint between the two for heat dissipation and image quality.
- X-ray tube focal spot size: Should be small to reduce image penumbra (blur) and increase x-ray energy.
Metastatic Deposit Tests
- Most sensitive test: Isotope scan. Other tests, like CT scan, skeletal survey, and X-ray scans, are also used to diagnose metastatic deposits, but are less sensitive.
Aortic Calcification Diagnosis
- Diagnostic method: Fluoroscopy, observing movement of aortic calcification (up-and-down, side-to-side, or combined movements).
CT Scanner Disadvantages
- Third-generation CT Scanners: Principal disadvantage is ring artifacts.
CT Scanner Advantages
- Second-generation scanners: Principal advantage is reduced scatter radiation, image noise, and scanning time.
First Generation CT
- Detector count: Used one detector(s) per rotation.
- Image information: Images store numerical information in Hounsfield units,
- Projection and reconstruction: Computed Tomography uses projections to reconstruct images.
Fourth Generation CT
- Detector features: Stationary detector array.
- Additional features: Reduced patient dose; other features like ring artifacts and detector arrays may also be present.
CT Projection Characteristics
- Variation factors: Density, contrasts, spatial resolution, and contrast resolution are recorded.
CT Scanner Voltage Generation
- Types of voltage generation include single, three, twelve, high frequency, and low frequency pulses.
CT Scanner Beam Types
- First to use fan beam technology: Third-generation scanner
CT Scanner Z-Axis Coverage
- Detector configuration: 1.25mm long detectors, total 16 rows, z-axis coverage is important for scanner function.
CT Scanner Beam Pitch
- Relationship: The relationship between beam pitch and collimator pitch is important in multiple-row detector CT scanners.
X-ray Attenuation
- Material factors: X-ray beam attenuation is affected by tissue composition and photon energy level, as well as closely related k-edge.
X-ray Image Purpose
- Imaging purpose: Produces images from the cross-section or cross section through a patient body with transmitted x-rays.
Data Acquisition System
- Abbreviation: Data acquisition system (DAS).
- Role: This converts the transmitted photons into digital information.
Advantages of Straton X-ray Tubes
- Benefits: Longer tube life, high-speed volume scanning.
Straton X-ray Tube Techniques
- High KV/low mA: Used for prolonged duration.
- Other techniques: Other high and low KV techniques are also possible for various reasons.
Filter Materials
- Material: Teflon is often used to make "bowtie" filters in x-ray imaging technologies.
X-ray Beam Size
- Overbeaming: A concern in CT where the x-ray beam is wider than the detector, creating an area outside of the detector's field of view which may be exposed to unnecessary radiation as determined by the amount that is wider.
- Overscanning is also a concern if the imaging area is not confined in the detector.
Section and Adaptive Collimation
- Techniques used to control overscanning and overbeaming.
CT Detector Signals
- Types: Electrical, mechanical, and US.
Detector Absorption Efficiency
- Factors affecting efficiency: The atomic number, physical density, size, and thickness of the detector face.
Conversion Efficiency
- Conversion purpose: To accurately convert absorbed/transmitted x-ray signals to electrical signals.
Diagnostic imaging system performance
- Data Acquisition purpose: The speed of the system determines factors like resolution, image noise, and speed.
Scintillation Detectors
- Conversion process: The scintillator material converts X-ray energy into photons. Then the detector converts light into electrical signals.
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Description
Explore the fundamental concepts of radiation detection, particularly focusing on ionization chambers, voltage impact, and the anatomy of X-ray tubes. Understand the significance of focal spot size and the sensitivity of various metastatic deposit tests. This quiz provides essential knowledge for students in radiation science and medical imaging.
