This document discusses common artifacts and positioning errors seen on panoramic radiographs. It describes ghost images, which are duplicate images caused when an object is penetrated twice by x-rays. It also discusses errors like open lips obscuring teeth, improper positioning of the chin resulting in overlapping structures, and movement during exposure causing blurring or duplication. Positioning the patient correctly in relation to the focal trough and keeping the spine straight are important to avoid errors.
brief description about CONTENTS Introduction Principles of panoramic imaging Image layer Panoramic machines Panoramic film Patient positioning Interpreting the panoramic imaging INDICATION Advantages Disadvantages Conclusion References
3. INTRODUCTION • Panoramic imaging also called pantomography is a technique for producing a single tomographic image of facial structures that includes both the maxillary and mandibular dental arches and their supporting structures . • This is a curvilinear variant of conventional tomography.
4. PRINCIPLES OF PANORAMIC IMAGE FORMATION • Patero and Numata - describe the principles of panoramic radiography • based on the principle of reciprocal movement of x-ray source and an image receptor around a central point or plane called the image layer, in which the OBJECT of image is located. • OBJECT in front or behind this image are not clearly captured because of their movement relative to the centre of rotation of the receptor and the x-ray source.
5. The film and x-ray tubehead move around the patient in opposite directions in panoramic radiography
6. ROTATION CENTER The pivotal point or axis around which the cassette carrier and tube head rotate is termed rotation center Three basic rotation center used in panoramic radiography Double centre rotation Triple centre rotation moving centre rotation The location and number of rotational centers INFLUENCE size and shape of focal trough
7. IMAGE LAYER • Also known as focal trough • It is a three dimensional curved zone where the structures lying within this layer are reasonably well defined on final panoramic image. • The structures seen on a panoramic image are primarily those located within image layer. • OBJECTSoutside the image layer are blurred magnified are reduced in size. Even distorted to the extent of not being recognizable. • This shape of image layer varies with the brand of equipment used.
8. FOCAL TROUGH
9. FACTORS AFFECTING SIZE OF IMAGE LAYER: Arc path Velocity of receptor and X-ray tube head Alignment of x-ray beam Collimator width The location of image layer change with extensive machine used so recalibration may be necessary if consistently suboptimal images are produced. As a position of object is moved within the image layer size and shape of image layer change.
10. PANORAMIC UNIT
11. A, Orthophos XG Plus extraoral x-ray machine. B, Orthoralix 8500 extraoral x-ray machine. C, Example of a digital panoramic system
12. PARTS OF PANORAMIC UNITS a. x-ray tube head b. head positioner: chin rest notched bite block forehead rest lateral head support c. exposure controls
13. X-RAY TUBE HEAD: • Similar to intraoral x-ray tube head • Each has a filament to produce electrons and a target to produce x-rays • Collimator is a lead plate with narrow vertical slit • Narrow x-ray beam emerges from collimator minimize patient exposure to radiation
1
brief description about CONTENTS Introduction Principles of panoramic imaging Image layer Panoramic machines Panoramic film Patient positioning Interpreting the panoramic imaging INDICATION Advantages Disadvantages Conclusion References
3. INTRODUCTION • Panoramic imaging also called pantomography is a technique for producing a single tomographic image of facial structures that includes both the maxillary and mandibular dental arches and their supporting structures . • This is a curvilinear variant of conventional tomography.
4. PRINCIPLES OF PANORAMIC IMAGE FORMATION • Patero and Numata - describe the principles of panoramic radiography • based on the principle of reciprocal movement of x-ray source and an image receptor around a central point or plane called the image layer, in which the OBJECT of image is located. • OBJECT in front or behind this image are not clearly captured because of their movement relative to the centre of rotation of the receptor and the x-ray source.
5. The film and x-ray tubehead move around the patient in opposite directions in panoramic radiography
6. ROTATION CENTER The pivotal point or axis around which the cassette carrier and tube head rotate is termed rotation center Three basic rotation center used in panoramic radiography Double centre rotation Triple centre rotation moving centre rotation The location and number of rotational centers INFLUENCE size and shape of focal trough
7. IMAGE LAYER • Also known as focal trough • It is a three dimensional curved zone where the structures lying within this layer are reasonably well defined on final panoramic image. • The structures seen on a panoramic image are primarily those located within image layer. • OBJECTSoutside the image layer are blurred magnified are reduced in size. Even distorted to the extent of not being recognizable. • This shape of image layer varies with the brand of equipment used.
8. FOCAL TROUGH
9. FACTORS AFFECTING SIZE OF IMAGE LAYER: Arc path Velocity of receptor and X-ray tube head Alignment of x-ray beam Collimator width The location of image layer change with extensive machine used so recalibration may be necessary if consistently suboptimal images are produced. As a position of object is moved within the image layer size and shape of image layer change.
10. PANORAMIC UNIT
11. A, Orthophos XG Plus extraoral x-ray machine. B, Orthoralix 8500 extraoral x-ray machine. C, Example of a digital panoramic system
12. PARTS OF PANORAMIC UNITS a. x-ray tube head b. head positioner: chin rest notched bite block forehead rest lateral head support c. exposure controls
13. X-RAY TUBE HEAD: • Similar to intraoral x-ray tube head • Each has a filament to produce electrons and a target to produce x-rays • Collimator is a lead plate with narrow vertical slit • Narrow x-ray beam emerges from collimator minimize patient exposure to radiation
1
this contains the occlusal radiography methods for both maxillary and mandibular different occusal radiographic techniques, principles, classification, indications
Bisecting angle vs paralleling technique /orthodontic courses by Indian denta...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
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IDEAL IMAGE CHARACTERISTICS
FACTORS RELATED TO THE RADIATION BEAM
FACTORS RELATED TO THE OBJECT
FACTORS RELATED TO THE TECHNIQUE
FACTORS RELATED TO RECORDING OF THE ROENTGEN IMAGE OF THE OBJECT
DARK/ LIGHT IMAGE IDEAL IMAGE
IDEAL QUALITY CRIETRIA
This presentation will give you a detailed knowledge about the various techniques that can be performed for imaging various aspects and diseases of TM Joint.
this contains the occlusal radiography methods for both maxillary and mandibular different occusal radiographic techniques, principles, classification, indications
Bisecting angle vs paralleling technique /orthodontic courses by Indian denta...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
IDEAL IMAGE CHARACTERISTICS
FACTORS RELATED TO THE RADIATION BEAM
FACTORS RELATED TO THE OBJECT
FACTORS RELATED TO THE TECHNIQUE
FACTORS RELATED TO RECORDING OF THE ROENTGEN IMAGE OF THE OBJECT
DARK/ LIGHT IMAGE IDEAL IMAGE
IDEAL QUALITY CRIETRIA
This presentation will give you a detailed knowledge about the various techniques that can be performed for imaging various aspects and diseases of TM Joint.
CLEANING AND SHAPING USING ROTARY ENDODONTIC INSTRUMENTS /certified fixed or...Indian dental academy
Welcome to Indian Dental Academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy has a unique training program & curriculum that provides students with exceptional clinical skills and enabling them to return to their office with high level confidence and start treating patients
State of the art comprehensive training-Faculty of world wide repute &Very affordable.
this slide briefs the correct positioning and some error in OPG and lateral cephalometric imaging. It also briefs the importance of correct positioning from the perspective of the maxillofacial surgeon.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
2. 1. GHOST IMAGES
This is a radiopaque artifact seen on a panoramic film
that is produced when a radiodense object is
penetrated twice by the Xray beam
3. The characteristics of a ghost image are:
i. A ghost image resembles it's real counterpart and has the
same morphology.
ii. It is found on the opposite side of the film from it's real
counterpart.
iii. It appears indistinct, the horizontal components are more
blurred than the vertical components of a ghost image.
iv. The ghost image is always larger than the real counterpart,
the horizontal component is severly magnified, whereas
the vertical component is not as severly magnified.
v. It is usually placed higher than its actual counterpart.
vi. Ghost images are always reversed. Left and right being
sifted.
4. Anatomical structures which are most
oftenghosted are:
i. Hyoid bone
ii. Cervical spine
iii. Inferior border of the mandible
iv. Posterior border of the mandible
v. The Meatuses
vi. The turbinates
5. • Non-anatomical structures which are often
ghosted are:
i. Chin rest
ii. (R) or (L) Markers of the machine
iii. Neck chains
iv. Napkin chains
v. Earrings
vi. Shoulder straps of protective aprons.
6.
7.
8. 2. LEAD APRON ARTIFACT
Lead apron artifact appears as a large cone
shaped radiopacity obscuring the mandible
9. 3.PATIENT POSITIONING ERRORS:
I. POSITIONING OF THE LIPS AND
TEETH
If the lips are not closed on the bite block, a dark
radiolucent shadow obscures the anterior teeth
10. II.POSITIONING OF THE
FRANKFURT PLANE
a. Upward :
If the patient's chin is positioned too high or tipped up (i.e. the chin is
too far forward while the forehead is titled towards the back):
– The hard palate and the floor of the nasal cavity appear superimposed
over the roots of the maxillary teeth.
– Loss of density in the middle of the radio-graph, usually characterized
by an hour glass shape.
– There is a loss of detail in the maxillary incisor region, magnification.
– The maxillary incisors appear blurred and magnified.
– Loss of one or both condyles at the side of the film.
11. The chin and the occlusal plane are rotated upward, resulting in the
overlapping of the images of the teeth and an opaque shadow (the hard
palate) obscuring the roots of the maxillary teeth
12. b. Downward
Ala-tragus line greater than 5° downward, the patient's chin is
positioned too low or is tipped down (i.e. chin positioned back and the
forehead is positioned forward);
– The mandibular incisors appear blurred.
– There is a loss of detail in the anterior apical region of the mandible.
The apices of the lower incisors are out of focus and blurred.
– The condyles may not be visible, as they may be cut off at the top of the
radiograph.
– Shadow of the hyoid bone is superimposed on the anterior aspect of the
mandible.
– Premolars are severly overlapped.
– An 'exaggerated smile line' is seen on the radiograph (severe curvature
of the occlusal plane).
13. An exaggerated smile seen on a panoramic film
when the patient’s chin is tipped down
14. III. POSITIONING OF THE TEETH:
a. Anterior to the focal trough
Patient's head is positioned too far forward.
– If the anterior teeth are not positioned in the
groove of the bite block, the teeth appear blurred.
– If the teeth are positioned too far Forward on the
bite block, the anterior teeth appear 'skinny' and
out of focus (Blurred and narrow).
– Spine is superimposed on the ramus areas.
– Premolars are severely overlapped.
15. The anterior teeth appear narrow and blurred on a panoramic film
when the patient is positioned too far forward on the bite block
16. b. Posterior to the focal trough:
Patient's head is positioned too far back
– If the anterior teeth are not positioned in the groove of
the bite block, the teeth appear blurred.
– If the teeth are positioned too far back on the bite
block, the anterior teeth appear 'fat' and out of focus
(blurred and wide).
– Excessive ghosting of mandible and spine.
17. The anterior teeth appear widened and blurred on a panoramic
film when the patient is positioned too far back on the bite block
18. IV. POSITIONING OF THE
MIDSAGITTAL PLANE:
If the patient's head is not centered, the
ramus
and the posterior teeth appear unequally
magnified. The side farthest from the film
appears magnified and the side closest to
the
film appears smaller.
19. The patient’s posterior teeth and ramus appear to be
magnified on the panoramic film when the head is not centered
20. a. Patient's head is tilted to one side.
– The side tilted towards the X-ray tube is enlarged.
– One condyle appears larger than the opposite one, the
neck also appears longer on the larger side.
– Image appears to be tilted, one angle of the mandible
is higher than the other.
21. b. Patient's head is twisted to one side causing the
mandible to fall outside the image layer, (one side is in
front of the image layer while the other side is behind
the image layer).
– Teeth on one side of the midline appear wide and have
severe overlapping of contacts, whereas the teeth on
the other side appear very narrow.
– Ramus on one side is much wider than the other side.
– Condyles differ in size
22. c. Whole head is off center position (patient
biting the block off center with lateral incisors or
cuspids).
– The molar teeth and the mandibular ramus are
magnified on the side farther from the film.
– Anterior teeth are blurred with overlapping
23. V. POSITIONING OF THE SPINE
If the patient is not sitting or standing with a
straight spine, the cervical spine appears as a
pyramid shaped radiopacity in the center of
the film and obscures diagnostic
information.
24. If the patient is not standing erect, superimposition of the cervical
spine may be seen on the center of the panoramic film
25. VI. PATIENT'S SHOULDER
TOUCHING THE CASSETTE
DURING EXPOSURE:
This will slow the cassette rotation, resulting in
prolonged exposure or completely stop the film
movement.
– Produces a dense black band, which is the area of
overexposure or a dense black edge may be seen at the
end of the radiographic image, due to eventual
stoppage of rotation.
26. VII. POSITION OF PATIENT'S TONGUE
DURING EXPOSURE:
If the tongue is not fully placed against the
roof of the mouth.
– A dark shadow appears in the maxilla
below the palate, and the apices of the
maxillary incisors are obscured.
27. If the tongue is not placed on the roof of the mouth, a radiolucent
shadow will be superimposed over the apices of the maxillary teeth
28. VIII. DISTORTION DUE TO PATIENT
MOVEMENT
a. Movement in the same direction as the beam.
– There is prolonged exposure of the same area, with
increase in horizontal dimension of the image
b. Movement in the opposite direction as the
beam.
– The horizontal dimension of the image in the
region is decreased
29. c. Sudden jerky movement in the same direction as
the beam.
– The area may be portrayed twice.
d. Sudden jerky movement in the direction
opposite the beam movement.
– A part of the object may be missing in the image.
e. If the patient moves up or down during exposure.
– Indentation in the lower border of the mandible
(mimicing a fracture)
– Blurring and unsharpness.
30. 4. CASSETTE POSITIONING ERRORS:
i. Patient's shoulders touching the cassette during the
movement in the exposure cycle. This may happen if
the patient has a short neck and well developed
shoulders.
– Alternating vertical dark and light bands appear on the
radiograph due to improper movement of the cassette
behind the slit in the cassette holder or the tube head
cassette holder assembly around the patient's head.
31. ii. Cassette placed too high.
– Lower border of the mandible is cut off.
iii. Cassette placed too low.
– Diagnostic information in the maxilla will be cut off.
iv. Two exposures on a single film.
Undiagnostic radiograph, with unnecessary exposure
to the patient.
32. v. Cassette placed backwards.
– This is common in panorex the X-rays must penetrate
the metal latch, which will present as a radiopaque
broad horizontal line through the middle of the
radiograph
