CBCT Basics Flashcards
Digital image processing/modifications include:
- compression
- imaging manipulations
- image reconstruction
Imaging manipulations = automated image analysis which includes:
Qualitative image analysis & Quantitative image analysis
Imaging manipulation that changes pixels digital value
qualitative
Imaging manipulation that counts the number of pixels:
quantitative
Data is utilized by other software programs and produces different image presentations:
Image reconstruction
Label the following views from the spiral CT Scan 3D image reconstruction:
- caudal cranial view
- buccal view
- distal view
- lingual view
- mesial view
- occlusal view
You don’t do a CBCT _____, you do a CBCT ____
Image; scan
Use of computers to generate multiple images of an object from digitized density information obtained from various signals; x-radiation (MDCT), (CBCT), magnetic fields (MRI), sonar radiation (ultrasound), etc.
Computed tomography
Two forms of x-ray CT:
- CBCT (Cone beam computed tomography)
- MDCT (Multi detector computed tomography)
CBCT and MDCT are both forms of:
x-ray CT
CBCT was developed in:
Japan Europe before 2000 A.D.
What was the first commercially available cone beam system in the U.S.?
NewTom (in 2001)
What version of Newtom was created in 2001?
NewTom 9000
NewTom 9000 was later renamed:
NewTom3G
NewTom 9000/ NewTom3G is similar to panoramic but captures:
density values of the whole object at different angles
NewTom 9000 (2001) is similar to the first:
MDCT in 1971
Describe the change of design from the NewTom3G to the NewTom VGi:
lay down versions –> stand up version
Label the names of the following machines:
Left: NewTom 3G
Right: NewTom VGi
How is the NewTom VGi EVO similar to a pano?
The patient stands while getting scanned
With the NewTom VGi EVO, the imaging capture process is _____ and the image processing is ____
short; longer
What device produced by Sirona is small r and used more often?
Orthophos XG 3D
Sironas Larger model =
Sironas smaller model =
Gallileo
Orthophos
What models did I-CAT FLX Create?
V8, V10, V17
What is significant about I-CAT FLX V8, V10, and V17 models?
Sit down models
Describe the advantages and disadvantages of a sit down unit:
Takes more time to get patient settled in but there is less chance for motion artifact
The faster the scan, the ____ but the lower the ____
less information; radiation dose
T/F: Most of the sit down units have a larger detector so they tend to be more expensive
True
List what CBCT models are made by CareStream:
CS8100 & CS9300 Select
Caresetream was originally _____ but went ____
Kodak; bankrupt
What models are shown in the following images?
CS 8100 (left)
CS 9300 Select (right)
What model is shown in the following image?
V8, V10 and V17 I-CAT FLX models
What model is shown in the following image?
Sirona Galileo
What model is shown in the following image?
Sirona Orthopthos
Both the CS8100 and CS9100 Select are ____ CBCT units
stand up
VaTech Picasso models are what type of CBCTs?
This company has both sit down and stand-up units
What model is seen in the image below?
VaTech Green 21 model
What models are shown in the following image?
VaTech Picasso models
What model is shown in the following image?
Morita X800
What CBCT unit is UMKC getting next year?
Morita X800
The larger the scan, the more time it takes= ____dose
The higher the dose
Due to a larger scan taking more time and ultimately have a higher radiation dose, you would prefer the patient to:
Sit in a chair so they don’t have to retake the scan
What type of CBCT do we currently have in the school that is Dr. Briners baby?
I-CAT FLX
What type of CBCT is seen in the image below?
Morita 3D Accuitomo 170
The CBCT brand Planmeca has what models?
Planmeca Viso G5; Planmeca Viso G7
What is the difference between the FOVs between Plameca Viso G5 versus Planmeca Viso G7
Plameca Viso G5 : FOVs: 3x3 cm and 30x17cm
versus Planmeca Viso G7: FOVs= 3x3cm; 30x19 cm and 30x30cm
Aside form the FOVs another difference seen between Plameca Viso G5 versus Planmeca Viso G7, is that the G7 uses a:
2 scan technique
T/F: Nearly all CBCT Units are good quality high-end imaging equipment made for a very competitive market place
True
CBCT units become outdated due to competition from:
- competitor brands
- technical innovations
List examples of technical innovations that contribute to CBCT units becoming outdated:
- memory
- bit depth
- FOV option
- Operating systems
- compatibility with software technologies
What technical innovation is being described below?
- how well it works with other digital systems to store the images
Memory
What technical innovation is being described below?
- Resolution
Bit depth
What technical innovation is being described below?
Site of scanner:
FOV options
The lifetime of CBCT unit is ~
6-8 years
Panoramic if used properly can last up to:
20 years (CBCTs are different)
What factors contribute to the shorter lifespan of 6-8 years of a CBCT unit?
- X-ray tube burns out
- Software system gets old (older systems don’t integrate well with newer softwares)
- Operating system changes
List the benefit of cone beam imaging
Less radiation than other forms of CT (i.e. MDCT) for hard tissue imaging
Explain the concept of less radiation from cone beam imaging for hard tissue imaging compared to other forms of CT:
- Less scanning of X-radiation
- Lower radiation
List the effective dose for the following CT exams:
1) CBCT large FOV
2) CBCT medium FOV
3) CBCT small FOV
4) MDCT- head
5) MDCT- abdomen
6) MDCT- chest
All measured in microSv (uSv)
1) CBCT large FOV: 68-1073
2) CBCT medium FOV: 45-860
3) CBCT small FOV: 19-652
4) MDCT- head: 960-1500
5) MDCT- abdomen: 5300
6) MDCT- chest: 5800
List the effective dose for the following CT exams in days background radiation:
1) CBCT large FOV
2) CBCT medium FOV
3) CBCT small FOV
4) MDCT- head
5) MDCT- abdomen
6) MDCT- chest
1) CBCT large FOV: 8-126
2) CBCT medium FOV: 5-101
3) CBCT small FOV: 2-77
4) MDCT- head: 101-177
5) MDCT- abdomen: 624
6) MDCT- chest: 682
1 day of background radiation is ~
8.5 microSV (uSv)
MDCT stand for ___, NOT ____
Multidetector CT; Not Medical CT
Why is there so much overlap in the effective dose for common CT exams?
There are other factors that affect the dose, not just considering the question of the size of the area being scanned
CBCT Dosimetry study values vary because:
studies are NOT directly comparable
CBCT Dosimetry study values vary because studies are NOT directly comparable, list examples of what we mean by this:
- variations in experimental methodologies
- different devises and settings
- different size FOVs including shapes of FOV
- differences in high and low resolution scans
- dosimetry phantoms
- ICRP E(1990) vs. E(2007)
Factors affecting dose of CBCT scan:
- FOV
- Exposure
- Voxel
- Sensors
- variations in experimental methodologies
- different devises and settings
- different size FOVs including shapes of FOV
- differences in high and low resolution scans
- dosimetry phantoms
- ICRP E(1990) vs. E(2007)
These are all causes of:
Effective dose of CT scans overlap
FOV=
Field of View
The Field of view referred to as the FOV refers to the:
Size of the volume captured in the scan
Almost all CBCT systems on the market capture a volume (FOV) that is shaped like a:
cylinder (tin can)
The FOV is expressed in 2 numbers typically measured in:
cm (online)
mm (slides)
The FOV is expressed in 2 numbers. The first number typically refers to the ____ of the cylinder, while the second number refers to the ___
The diameter of the circular face of the cylinder (top of the pop can) while the second number refers to the height
What is the shape of a flat panel detector (CBCT FOV)
Cylinder (popcorn)
List the steps of the CBCT unit:
- image acquisition
- raw data (2D projection)
- image reconstruction (3D dataset)
- visualization (2D slices, etc)
The field of view size can be selected and positioned according to the:
diagnostic task
CBCT units have capabilities for scanning a range of:
FOV sizes
T/F: You pick the field of view you need and then position the patient in the CBCT unit
False- You position the patient first and then pick the filed of view you need according the area being imaged
The _____ needs to be in the selected field of view
area being imaged
What is the difference between the PaX-i3D Smart and the PaX-13D Premium?
PaX-i3D premium has multi FOV leading to more area being imaged (you can image the whole skull with this)
If you are wanting to capture a full skull image compared to a small area of teeth, you would need:
A larger detector (more expensive)
What is the FOV for these images?
8cm x 15cm
What is the FOV for these images?
13cm x 15cm
What is the FOV for these images? What can this be considered?
26cm x 15cm (extended FOV)
CBCT factors affecting dose:
- FOV
- Exposure
- Voxel
- Sensors
The kV ranges for CBCT based on:
unit
When discussing kV of a CBCT we are talking about:
exposure
What is the kV range between various CBCT units?
75kV-120kv
What is the mA ranges between various CBCT units?
7mA-20mA
When talking about exposure, ____ is affected by basis image data:
time
X-ray beam projection scheme shows _____ imaging geometry with the resultant imaging production
cone beam
In CBCT image production, multiple ____ projections form the ____
basis image; projection data
After the CBCT unit forms multiple basis image projections forming the projection data, A ____ is then constructed by an imaging software program.
Volumetric data set
A ____ is constructed by an imaging software program which then displays various ____
volumetric data set; image recontstructions
The image reconstructions produced by the imaging software program from the volumetric data set is depend on the power of the programs as specified by the:
software manufacturers
X-ray beam projection scheme shows a “cone” beam imaging geometry with the resultant production of:
a basis image
To obtain projected images, the X-ray tube and detector move ___ around the ___
concomitantly; axis of rotation
To obtain projected images, the ___ and ___ move concomitantly around the axis of rotation
X-ray tube and detector
_____as the machine rotates counterclockwise from position 1 to position 2
two basis-image capture sequences
What way does a CBCT machine rotate?
counterclockwise
CBCT scans routinely capture in the range of ____ to ____ basis images per rotational scan
100-600
CBCT scans routinely capture a range of 100 to 600 ___ per ___
basis images; rotational scan
When a low number of ___ is used, the object is under sampled and the image exhibits streaks along the direction of the back projected rays:
projections
How could you fix this if this were the result of your CBCT scan?
An improved reconstruction is possible when the number of projection angles is increased
The number of basis images affects:
- image quality
- dose
The number of basis images affects image quality and dose, explain:
The more basis images captured= the more detailed the reconstruction will be however, the more basis image captured = the more radiation the patient is exposed to
The smaller the voxel size =
better the image because of higher resolution
Factors affecting dose include:
- exposure settings (kV, mA, Time)
- resolution (voxel size)
- FOV
The smaller the voxel size the ____ obtained
more information
Which image is the result of a smaller voxel size?
Image A
A voxel size of 0.3mm cubed =
300 micrometers cubed
A voxel of 0.075mm cubed =
75 micrometers cubed
Small voxel yields ___ resolution
higher
Small voxel size yields LOWER ___
Signal to noise ratio
Small voxel size yields ____ radiation dose
higher
Why might small voxel size after a certain point result in degraded image quality?
smooths too much due to Compton scatter (signal to noise ratio)
What is the voxel size for larger FOVs?
Greater than or equal to 0.200 mm= 200 micrometers
What is the voxel size for smaller FOVs (less than or equal to 5cmx5cm)
Less than 0.200mm = 200 micrometers
Small voxel yields high resolution but requires ____ (___) to capture signal in the greater number of the smaller voxels
more x-ray photons (higher exposure)
T/F: Current scanners are not configured for the longer scan times and longer processing times for a large FOV with a small voxel size
True
Smaller voxels need more ____ which yields a higher ___
photon signal; radiation dose
Sensors are also known as:
detectors
A panoramic focal trough is a ____ focal trough
3D
Label what kind of image detectors are seen in the CBCT units below?
left: charge-coupled image intensifier detector
right: flat-panel detector
Label which detector produces the following distortion patterns:
A: Image-intensifier detector
B: Flat-panel detector
Grid type X distortion pattern is a result of:
image-intensifier detector
Grid type Y distortion pattern is a result of:
Flat-panel detector
With a grid type x (image-intensifier detector) distortion pattern, distortion of the image grid occurs:
when moving away from the center
For this type of image detector, even at more distant areas from the center of the grid, there is minimal to no distortion of the grid pattern:
Flat-panel detector (Grid Y)
Improved image quality an higher signal-to-noise ratio are seen with what type of image detector?
Flat-panel
What type of image detector results in a lower radiation dose?
CCD image intensifier
CBVT:
Cone beam volume tomography
DCT:
Dental CT (bad term)
MCT:
Micro CT (Bad term)
3DI:
3D imaging (terrible term)
