GE CT Features Flashcards
What is ASiR-V?
- Adaptive Statistical iterative Reconstruction
- A reconstruction technique that reduces image noise and streak artifact which thereby reduces the dose required for routine imaging.
- Prescribed in 10 percent increments for 10-100 percent.
What is MTF?
Modulation Transfer Function is a measure of how well an imaging system transfers an object’s contrast to an image and is made up of two components: resolution and contrast/modulation.
What is DLIR?
- Deep Learning Image Reconstruction
- Also referred to as True Fidelity
- Deep-learning based reconstruction method intended to produce cross-sectional images of the head and whole body by computer reconstruction of X-ray transmission data taken at different angles and planes.
- Intended for image reconstructions to remove noise from the image but with a desire for texture that is more consistent with Filter Back Projection image reconstruction.
- Can be set to low, medium or high
What is IQ Enhance?
- Reconstruction process that can be used to minimize helical artifacts
- Must be 0.625 or 1.25 slice thickness at an interval equal to or exactly one half slice thickness.
- Not compatible with Axial, Cine or cardiac scan types.
Why is properly centering the patient in the gantry important?
To allow the bowtie filters to deliver dose where it is needed and filter more where it is not. Improperly centered patients may be under or over exposed if table height is set too high or too low.
*Especially important when using SmartmA or the mA selected by the system may be inadequate or greater than required.
When is SmartmA not recommended?
When a larger patient must have the table position lower than desired to fit into gantry and patient is miscentered. Manual mA is recommended in these instances.
What is SmartmA?
- An automatic tube current modulation feature that makes the necessary mA adjustments much more accurately than those manually estimated for the patient, and can thereby achieve a more consistent image noise in spite of the wide range of patient size.
- Uses last scout performed and selected noise index setting to select mA ranges
- Adjusts exposure as tube rotates thus leading to mA modulation in the x, y and z-axes.
How does ASiR effect SmartmA?
Increasing the ASiR-V percentage in SmartmA lowers the mA value required to achieve the prescribed NI.
What are the three categories of inputs that SmartmA uses to select the mA values?
- Patient-dependent
- Scan technique
- Primary image reconstruction parameters
How does SmartmA receive the patient-dependent values to calculate the prescribed mA?
It receives the attenuation size and shape of the anatomy being scanned from the last scout performed.
List the Scan Techniques used by SmartmA to calculate prescribed mA.
- Scan type (axial, cine, helical, cardiac)
- kV
- SFOV
- Rotation time
- Detector Coverage (helical only)
- Standard or High-Definition mode
List the Primary image reconstruction parameters used by SmartmA to calculate the prescribed mA.
- Noise index
- Slice thickness
- ASiR-V percentage
- Reconstruction type (HD or non-HD kernel)
What is ODM?
A mode to reduce the tube current (mA) when the x-ray tube is in the anterior position relative to the patient.
*Apex head 100 degrees
*Apex body 150 degrees
*Ascend head 90 degrees
*Ascend body 180 degrees
What is the mA reduction rate for ODM in the Head, Small Head, Ped Head SFOV?
Up to 30% with a ??? degree mA reduction range.
What is the mA reduction rate for ODM in the Large Body, Medium Body, Small Body, Ped Body SFOV?
Up to 40% with a 150 degree mA reduction range.
What is Auto Prescription?
A profile-driven feature that automatically selects kV, pitch, rotation time and other scan settings based on patient size. Utilizes AP + Lateral calculated from scout images to select size based profile.
What are the two key areas that Auto Prescription enhances for the CT user and the patient experience?
- Balances dose and image quality across all patient sizes by selecting scan settings and optimizing noise index and dose based on patient size.
- Improves workflow by eliminating size-based protocolling and reducing scan time adjustments and variability.
Define Helical Full mode
- It is a recon mode that provides a thinner slice profile but requires 10-15% more mA than Plus mode with equal noise.
Define Helical Plus mode
- A recon mode with up to 20% wider slice profile than full, but requires 15-20% less mA with equal noise. Provides reduced image noise.
- Reduction of helical artifacts can be seen with Plus mode.
- Uses additional views of data to reconstruct an image.
-Exposure time increases slightly to ensure views are collected to reconstruct all image locations prescribed.
Auto Scan
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What is Noise Index?
The relative level of noise in the reconstructed image and is the primary SmartmA input parameter that controls the X-ray output and ultimately provides the tradeoff between the desired image quality and patient dose.
The Noise Index value will equal what?
Approximately the standard deviation in the central region of the image when a uniform phantom is scanned and reconstructed using the standard reconstruction algorithm.
What does a higher Noise Index mean?
The image will contain relatively more noise and will be obtained with lower mA, therefore lowering relative patient dose.
What does a lower Noise Index mean?
The images will contain relatively less noise and will be obtained with higher mA, leading to relatively higher patient dose.
DLIR is not available in _____________ reconstructions.
primary
What is enhanced contrast?
A special reconstruction option for head CT’s to boost the differentiation between the gray and white matter regions in the brain.
Describe the EC selections in Enhanced Contrast
Focuses on CT number separation of gray and white matter for better differentiation.
Describe the EB selections in Enhanced Contrast
Focuses on improving the gray and white edge boundary resolution for better differentiation.
What is SmartMAR?
A reconstruction technique that reduces photon starvation artifacts caused by metal implantations.
metal artifact reduction.
What is Intelligent Protocolling?
Enables automatic recommendations of protocols to the user for a study.
How does Intelligent Protocolling work?
- The system tracks the most commonly selected protocols for the worklist key from the patient worklist and displays up to 6 protocols in the “Recommended Protocol” area.
- The recommended protocols display only if a protocol has been selected at least 5 times for a given Worklist key.
How can you verify if intelligent protocolling is installed?
It will list on System Preferences
What is SmartPlan?
A protocol driven feature that uses the patient’s scout scan to set scan and recon range, DFOV, A/P & R/L center based on recognition of anatomical landmarks from valid scout images.
How does SmartPlan determine and display the initial scan or recon range settings to the technologist for each group?
When enabled, SmartPlan uses the prescribed Clinical Identifier (CID) to determine which anatomical landmarks to look for and then sets the parameters.
What anatomy can SmartPlan detect?
- Head
- Chest
- Abdomen
- Pelvis
And combinations of the chest, abdomen and pelvis.
When can SmartPlan be enabled?
Only in Protocol Management. SmartPlan settings are not displayed and cannot be enabled at scan time.
What is GSI?
- Gemstone Spectral Imaging enables the acquisition, reconstruction and visualization of spectral or GSI imaging.
- Fast energy switching providing data from two different kVp energies.
- Provides reduced beam hardening and metal induced artifacts.
What is Smart Phase?
A cardiac reconstruction that automatically selects the phase of least motion within the earliest acquisition part or each acquisition part with mA greater than 50% of peak mA.
What is Hi Res mode?
Provides the capability to acquire 2.5 more views using deflection of the X-ray beam.
What is the PDU?
- Power Distribution Unit supplies power to gantry, table and operator console.
- There is a power on light, a push button (Gantry Enable) to turn power on/off to the gantry and table and an Emergency Stop button.
What happens when Emergency Stop button is pushed?
Stops all table and gantry motions, X-ray is stopped, laser alignment lights are turned off and the cradle and base become unlatched. The system aborts any data acquisition in progress and will attempt to save any data acquired.
What is the System Cabinet?
- Contains the acquisition and image generation computer hardware along with supporting electronics.
- Supplies interfaces between scanner desktop and the gantry allowing for acquisition control, raw data storage and image generation process.
Review purchasable options on page 194 Apex User Manual
What is smart coverage?
System adjusts to best detector coverage based on the start and end location prescribed.
What is temporal enhance?
Reconstruction mode to create images to support SnapShot Freeze cardiac image post processing.
What is SnapShot Freeze?
A reconstruction feature that can be used to reduce coronary artery motion artifacts that may occur in cardiac exams.
What is recon type?
The reconstruction algorithm or kernel.
Describe features of High Resolution scanning?
-Increases spatial resolution
-Used in conjunction with high def algorithms
-Focal spot deflection
-Over sampling
-Reduces calcium blooming
-Increases image noise
-Up to 2,496 views
What is a Clinical Identifier?
To define exam into a clinical category and specific procedure for image reconstruction and post processing tasks.
What is lock group delay?
When turned on system will display an alert if the group delay changes by 5 seconds or more from the prescribed delay.
What are the functions of the Power Distribution Unit (PDU)?
-Supplies power to gantry, table and operator console
-Contains power indicator light, power on/off button to gantry and table
-Emergency Stop button
What are the functions of the System Cabinet?
-Contains acquisition and image generator hardware
-Interfaces between desktop and gantry
-Allows acquisition, raw data storage and image generation process
What are the functions of the Uninterrupted Power Supply (UPS)?
Allows system components, scanner desktop, system cabinet and table to remain operational for the duration of the battery life. Scanning disabled.
40 mm detector
64 X 0.625
125 X 0.3125
80 mm detector
128 X 0.625
256 X 0.3125
160 mm detector
256 X 0.625
512 X 0.3125
How to brief A1 panel
Per OSHA any electrical equipment that is greater than 50 volts must only be operated by qualified individuals that are trained in electrical safety protocols and procedures.
What is Fine Z reconstruction?
-Designed for high resolution, detailed neuro axial acquisitions such as temporal bones.
-Recommended for significant use of oblique reformats
-Can be applied either to primary or secondary reconstructions
-Only for high resolution kernels and highest z direction sampling (0.625z)
What is the purpose of the clinical identifier?
-For networking prioritization of stroke and trauma tags
-For SmartPlan
What is MaxFOV 2?
-Allows reconstructions of up to 80 cm FOV image
-For head and whole body scans
-Image quality degrades outside of scan FOV, CT number accuracy differs and not for diagnostic imaging
When is “Less” exposure level selected for SmartScouts?
Pediatrics 35 cm or less in diameter
See chart on pg 287 Apex User Manual
When is “Moderate” exposure level selected for SmartScouts?
Pediatric/Adult patients between 13 and 39 cm in diameter
See chart on pg 287 Apex User Manual
When is “More” exposure level selected for SmartScouts?
Adult patients 35 cm or more in diameter
See chart on pg 287 Apex User Manual
What is Fine Z used for?
- Clinical tasks which require significant use of oblique reformats or sag or cor views.
- May be applied to either primary or secondary reconstructions.
- Increased Z axis resolution and only available for high resolution kernels.
What is Recon Mode Plus?
- The system provides a plus recon mode for an Axial scan type.
- Only available on secondary recons.
- Can be combined with ASiR-V
- Only available for collimations greater than or equal to 40 mm.
What is Auto View?
Displays scouts and non-clinical QC images.
What is Auto Scan?
- If turned off, the move to scan button must be pressed for every scan before start scan will be ready.
- If Auto scan is on during one group, it will remain on for every group in that series.
