CBCT Artifacts | Basic CBCT| CBCT basic understanding | Cone beam computed tomography

Summary

This dental radiology video explores the various artifacts that can affect CBCT image quality, categorizing them into inherent, procedural, introduced, and patient motion artifacts. It explains how physical limitations, such as X-ray geometry and image reconstruction methods, contribute to inherent artifacts like cone beam artifacts and quantum noise. Procedural artifacts stem from under sampling and scanner issues, leading to misregistration and distortion. Introduced artifacts are caused by beam hardening, resulting in cupping and streaks. Lastly, patient motion artifacts can cause data misregistration, appearing as shading or streaking. The video also offers tips to minimize these artifacts for clearer dental imaging.

Takeaways

• 🌟 Dental radiology image artifacts in CBCT can be categorized into inherent, procedure-related, introduced, and patient motion artifacts.
• 🔍 Inherent artifacts stem from physical limitations such as the geometry of the X-ray cone, its trajectory, rotational arc, and the image reconstruction method of the software.
• 📈 Quantum noise, or strict artifacts, and the cone beam effect are examples of inherent artifacts that can degrade image quality.
• 📊 The partial volume artifact occurs in both CT and CBCT, where a single voxel contains multiple tissue densities, leading to an averaged, inaccurate representation.
• 🛠 Procedural artifacts can result from under-sampling, causing misregistration and streaking artifacts, or scanner issues leading to circular artifacts.
• 🌀 Beam hardening artifacts occur when the X-ray beam's energy changes after passing through dense objects, causing distortions in the image of metallic structures.
• 🏥 To mitigate beam hardening artifacts, adjust the field size, modify patient positioning, or separate the dental arc to avoid scanning metallic dental implants or restorations.
• 🚫 Removing metallic objects like jewelry before scanning can help reduce peripheral beam hardening effects on the region of interest.
• 🏃‍♂️ Patient motion artifacts arise from movement during the scan, leading to misregistration and potential shading or streaking in the image.
• 📢 The video emphasizes the importance of understanding and managing these artifacts to ensure accurate diagnostic imaging in dental radiology.

Q & A

What are the main factors that affect CBCT image quality?

The main factors affecting CBCT image quality are image artifacts and distortions, which can be unrelated to the object or artificially appearing on the image but not part of the tissue being examined.

How can dental radiology image artifacts in CBCT be classified?

Dental radiology image artifacts in CBCT can be classified into inherent artifacts, procedure-related artifacts, introduced artifacts, and patient motion artifacts.

What are inherent artifacts in CBCT?

Inherent artifacts arise from limitations in physical processes due to the geometry of the X-ray, such as the cone-beam effect, trajectory, rotational arc, and image reconstruction method of the software.

What is the cone beam effect and how does it affect image quality?

The cone beam effect, or V artifact, occurs because the X-ray beam is cone-shaped and has divergence. This results in less data collection at the periphery compared to the center, leading to streaking artifact and noise at the edges of the image.

What is a partial volume artifact and how does it appear in CBCT?

A partial volume artifact occurs when different tissue densities are present in one voxel, causing the final density displayed to be an average rather than the real density of the individual tissues.

What are procedure-related artifacts and how do they occur?

Procedure-related artifacts include under sampling artifacts and scanner-related artifacts. They occur when there is a large interval between projections or sections, causing misregistration of data and visible artifacts like fine hypodense and hyperdense strips.

What is a circular artifact in CBCT and what causes it?

A circular artifact in CBCT is caused by a detector being out of calibration, resulting in a constantly reading error at each angulation of the tube, which manifests as a circular pattern in the image.

How does beam hardening affect CBCT images?

Beam hardening occurs when the X-ray beam passes through dense objects, causing lower energy photons to be absorbed and the mean energy to increase. This can result in artifacts such as distortion in the image of metallic structures and dark streaks between dense objects.

What are introduced artifacts and how can they be reduced?

Introduced artifacts include cupping artifact, streaks, and dark bands caused by beam hardening. They can be reduced by adjusting the field size, modifying patient position, or separating the dental arc to avoid scanning regions with metallic objects.

What are motion artifacts and how do they appear in CBCT images?

Motion artifacts are caused by patient movement during the scan, leading to misregistration of data and appearing as shading or streaking in the image, sometimes causing a double contour of bones.

Why is it important to remove metallic objects before scanning in CBCT?

Removing metallic objects like jewelry before scanning in CBCT is important to reduce peripheral beam hardening effects that can superimpose on the region of interest and degrade image quality.

Outlines

00:00

📈 Understanding CBCT Image Artifacts

This paragraph discusses the various types of artifacts that can affect the quality of CBCT (Cone Beam Computed Tomography) images in dental radiology. The speaker, Farida, introduces the concept of image artifacts, which are distortions or errors unrelated to the actual tissue being examined. The artifacts are categorized based on their causes: inherent, procedure-related, introduced, and patient motion artifacts. Inherent artifacts stem from limitations in the physical processes, such as the geometry of the X-ray beam and the image reconstruction method. Specific types of inherent artifacts include scanner artifacts, quantum noise, cone beam effect, and partial volume artifacts. The paragraph also explains the causes and effects of each type of artifact, providing insights into how they can be identified and potentially mitigated in dental imaging.

05:04

🔍 Addressing Beam Hardening and Motion Artifacts in CBCT

The second paragraph delves into the specific types of artifacts related to the X-ray beam and patient movement. Beam hardening artifacts occur when the X-ray beam passes through dense objects, causing a change in the mean energy of the beam and leading to distortions in the image. This can result in cupping artifacts, streaks, and dark bands. To reduce these effects, the speaker suggests techniques such as reducing the field size, modifying patient position, and removing metallic objects before scanning. Motion artifacts, caused by patient movement during the scan, can lead to misregistration of data and appear as shading or striations in the image. The speaker emphasizes the importance of patient stability during the scanning process to minimize these artifacts. The paragraph concludes with a call to action for viewers to subscribe, share, and stay updated for future educational content.

Keywords

💡Image Artifact

An image artifact refers to any distortion or error in an image that is unrelated to the object being examined. In the context of the video, these artifacts can appear as artificial elements on dental radiographs that do not belong to the tissue being examined. They can be caused by various factors such as the geometry of the X-ray beam, the scanning process, or patient movement. The video discusses different types of artifacts, including those caused by inherent limitations in the imaging process, such as 'cone beam effect' or 'partial volume artifact'.

💡Cone Beam Computed Tomography (CBCT)

CBCT is a specific type of X-ray imaging used in dental radiology that provides three-dimensional images of the structures within the oral and maxillofacial regions. The video script discusses various artifacts that can occur in CBCT images, emphasizing the importance of understanding these artifacts for accurate diagnosis and treatment planning in dental radiology.

💡Quantum Noise

Quantum noise, also known as quantum mottle, is a type of image noise that arises due to the statistical variation in the number of photons detected. In the video, it is mentioned as a factor that can decrease image quality, particularly when X-ray photons are absorbed, leading to a grainy appearance or 'strict artifacts' in the image.

💡Cone Beam Effect

The cone beam effect, or 'V artifact,' is an inherent artifact that occurs due to the geometry of the X-ray beam in CBCT. As the X-ray beam diverges, the peripheral parts of the image receive less data compared to the center, leading to a decrease in image quality at the edges. This is illustrated in the video with the example of the red graph showing the effect of uneven data collection in the peripheral areas.

💡Partial Volume Artifact

A partial volume artifact occurs when a single voxel in a CT or CBCT scan contains multiple tissue densities, resulting in an average density that does not accurately represent any single tissue type. The video uses the example of a voxel containing both bone and adjacent soft tissue, where the displayed density is neither bone nor soft tissue, thus not showing the real density.

💡Under Sampling Artifact

Under sampling artifacts are procedural-related artifacts that happen when there is a large interval between projections or sections, leading to misregistration of data. The video describes this as causing 'fine strips' or 'streaks' that radiate from the edges of dense structures, particularly noticeable in the peripheral areas of the image.

💡Scanner Artifact

Scanner artifacts are related to the hardware of the imaging device and can include issues such as bad pixels in the detector. The video mentions that if one of the detectors is out of calibration, it can result in a 'circular artifact' or 'ring artifact' appearing in the image at each angulation of the X-ray tube.

💡Beam Hardening Artifact

Beam hardening artifacts occur when the X-ray beam passes through dense objects, causing lower energy photons to be absorbed and the remaining higher energy photons to increase the mean energy of the beam. This can lead to distortion in the image of metallic structures or 'dark streaks' between two dense objects, as discussed in the video. To mitigate this, the video suggests reducing the field size or modifying the patient's position.

💡Motion Artifact

Motion artifacts are patient-related and occur due to patient movement during the imaging process. These can cause misregistration of data, leading to 'shading' or 'striking' in the image, such as double contours of bones. The video emphasizes the importance of minimizing patient movement to avoid such artifacts.

💡Metallic Artifact

Metallic artifacts are introduced artifacts that can result from the interaction of the X-ray beam with dense metallic objects like dental implants or restorations. The video explains that these can cause distortion in the image or dark streaks between dense structures, and suggests removing metallic objects like jewelry before scanning to reduce these artifacts.

Highlights

Image artifacts in CBCT can be classified according to their etiology.

Inherent artifacts arise from limitations in physical processes.

Scanner artifacts occur when X-ray photons are diffracted from their original path.

Quantum noise is a type of inherent artifact that affects image quality.

Cone beam effect or a V artifact is caused by the geometry of the X-ray beam.

Partial volume artifact occurs when different tissue densities are present in one voxel.

Procedural related artifacts include under sampling artifacts and scanner related artifacts.

Under sampling artifact can cause misregistration of data at sharp edges.

Circular artifact or ring artifact occurs when a detector is out of collaboration.

Introduced artifacts include beam hardening artifacts like cupping and streaks.

Beam hardening artifact can cause distortion in the image of metallic structures.

Dark streak artifact occurs between two dense objects due to beam hardening.

To reduce beam hardening artifacts, one can modify the field size or patient position.

Metallic objects like jewelry should be removed before scanning to reduce beam hardening effect.

Motion artifacts are caused by patient movement and can appear as shading or streaking.

Double contour of bones can be seen with motion artifacts.

Transcripts

foreign

[Music]

the fundamental factories that affect

the cbcd image quality is the image

artifact and artifices any Distortion or

error in the image that is unrelated to

the object or something artificial that

appears on the image but is not a part

of the tissue being examined

hi there I'm farida if you're new here

welcome if you've been here welcome back

to the dental radiology

image artifacts in cvcd can be

classified according to their etiology

inherent artifacts procedure related

introduced artifacts and patient motion

artifacts

today's classification is

the book of why dinosaur or Radiology

principles and interpretation

inherent artifacts arise from limitation

in physical process due to geometry of

the X-ray that is like a cone

reduce trajectory rotational Arc

and image reconstruction method of the

software

these are the subtitles of the inherent

artifacts

scanner artifact

x-ray photons are diffracted from their

original path after interacting with the

object because CBC use area detectors

the scanner photons are absorbed and

decrease the image quality we call it

quantum noise so what we see

is strict artifacts

or we can have a greatness appearance is

like small dots on the image

cone Bean effect or a v artifact

of course because the beam is like a

cone and we have divergency of the X-ray

beam

when the X-ray rotates showing two

position of the exterior tube zero

degree and 180 degree the center Parts

get maximum amount of data collection by

the detector for reconstruction but the

peripheral the amount of data collection

is less the red graph shows the effect

of and educate data in the peripheral

that would be in the superior and the

inferior

it is seen at the edges or the

peripheral portion of the image the

result is stricking artifact and noise

in the peripheral

partial volume artifact this artifact is

seen in both CT and cbct

when one soft tissue is presented in a

single voxel the density that is seen

shows the exact density of the soft

tissue

when the voxel size is larger than the

object so different tissue density are

present in one book cell so the final

density that shows will be an average

and not showing the real density for

example a voxel contain both bone and

adjacent soft tissue but the display is

neither bone or soft tissue

procedural related artifacts contain

under sampling artifacts and scanner

related artifacts

under sampling artifact when we have

large interval between projection

or the section

and can cause misregistration of the

data in the sharp edges The View we see

can be called a lysine artifact fine

strips if you're like radiating from the

edges of dense structures like the skull

bone on this cbct particularly on the

peripheral we can see fine hypotens and

Hyper dense strips

if you are to be radiating from the

edges of the bone it can also be called

the moyer pattern

circular artifact or ring artifact if

one of the detectors is out of

collaboration like we have a bad pixel

the detector will give a constantly

reading error at each angulation of the

tube resulting a circular artifact

introduced artifacts

that is the beam parting artifact

contains two categories cupping artifact

and streaks and dark bonds being

hardening artifact when x-ray beam

passes through a dense object like a

crown restoration lower energy photons

are absorbed but higher energy photons

pass through the mean energy increase so

the beam becomes hard and it penetrates

two types of artifacts can be the result

from this effect

copying artifact Distortion in the image

of metallic structures

x-ray passed through the mid portion of

the object and are hardened more than

those passing the edges

because soft

extra photons are absorbed more

so we can see the Distortion in the

image of metallic structures

and we have this strict

dark artifact

that happens

between two dense objects

like

um

dental implants and dental restoration

that we can also call them extension

artifact or missing Valley artifact

so we have a hard x-ray that can burn

that part of our image and manifest as

dark stricts between two highly

alternation structures

to reduce the beam Harding artifact we

can reduce the field size or we can

modify the patient

or we can separate the dental Arc to

avoid scanning region like dental

implants or dental Restorations

that are metallic

and it's also important to remove

metallic objects like jewelry before

scanning to reduce the peripheral beam

Harding effect that can be superimposed

on the region of interest that is being

imaged

motion artifact that would be the

patient artifacts due to the patient

movement and can cause misregistration

of the data and can appear as shading or

striking

we can see double Contour of the bones

with double strict

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