30 Questions
What is the purpose of normalizing CT numbers to the attenuation value of water?
To allow comparison of tissue densities
What term is used to represent tissue density in a CT image?
CT numbers
What is the CT number of air on the Hounsfield unit (HU) scale?
-1000
What is the basic principle behind Cone Beam Computed Tomography (CBCT) imaging?
Directing a collimated cone x-ray through the region of interest
Which of the following is an indication for Maxillofacial Multidetector Computed Tomography?
Developmental anomalies of craniofacial skeleton
What do CT numbers represent in a CT image?
Tissue density
What is the purpose of capturing multiple sequential planar projection images during rotation?
To produce basis images for interpretation
How are basis images different from cephalometric radiographic images?
Each basis image is slightly offset from the next, unlike cephalometric images
What determines the number of images that constitute the projection data in CBCT imaging?
The completeness of the trajectory arc and rotation speed
Which component of image production involves stabilizing the patient and setting the X-ray generator parameters?
X-ray generation (Acquisition)
In CBCT imaging, what remains constant for the X-ray source during image acquisition?
Focal spot size
What role does the detector frame rate play in determining the number of images in CBCT projection data?
Affecting the completeness of the trajectory arc
What is one of the advantages of CBCT compared to CT?
Reduced size & cost
Which feature of CBCT allows for real-time dimensional assessment and measurements?
Interactive analysis
What is one of the disadvantages of CBCT imaging mentioned in the text?
Image noise/artifacts
Which aspect of CBCT allows for unique display modes in maxillofacial imaging?
Interactive display modes
What is one difference between CBCT and medical CT?
CBCT offers variable FOV
Which publication compares maxillofacial CBCT and medical CT?
Atlas Oral Maxillofac Surg Clin North Am.
What is the basic principle of Computed Tomography (CT) imaging technique?
A collimated x-ray source and a detector rotate around the patient.
What advantage of CT imaging eliminates the superimposition of images?
Detailed visualization of structures outside the area of interest
Which generation of CT scanner uses a solitary x-ray pencil like beam and a solitary detector?
First Generation CT
What is the characteristic of the fan beam in Second Generation CT scanners?
It rotates around the patient in small increments.
Which feature makes CT a painless imaging technique?
Non-invasive nature
What does the detector in CT scanners record during imaging?
Photon attenuation
What is the role of flat panel detectors (FPDs) in X-ray detection for CBCT imaging?
Serving as an alternative to image intensifier tube/charge-coupled device (II/CCD) combination
What does the grayscale ability of CBCT imaging depend on?
The detector's capability to show accurate contrast differences
How many shades of gray can current CBCT machines identify with their 12 bit detectors?
4096 shades of gray
What occurs during the secondary (multiplanar) reconstruction stage in CBCT imaging?
Creation of sagittal, coronal, or axial images
What is the significance of voxel size in CBCT imaging?
It is equal in all three dimensions
In CBCT imaging, what is the process involved in dividing the volume into tiny cubes or voxels?
Primary reconstruction
Learn about basis images in oral medicine and radiology, which are sequential planar projection images captured during rotation. Understand how basis images resemble cephalometric radiographic images but are slightly offset from each other.
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