The copper in a stationary anode plays a dual role:
1. It supports the tungsten target.
2. It efficiently removes heat from the tungsten target.
Copper acts as a heat sink, drawing heat away from the tungsten target to prevent it from overheating due to the energy deposited by bombarding electrons.
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X-Ray physics including x-ray tube, transformer, generator, and rectifiers. physics made an easy
Note: this ppt has many animations that may not be appreciated over here. Request original ppt at kajalsradiology@gmail.com
X- Ray physics- X-Ray Tube, Transformer, Generator and Rectifiers by kajalsra...DrKajalLimbad
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X-Ray physics including x-ray tube, transformer, generator, and rectifiers. physics made an easy
Note: this ppt has many animations that may not be appreciated over here. Request original ppt at kajalsradiology@gmail.com
*Create fun conversations.* Stickers, GIFs, Poptexts & more. Download Bobble Keyboard Now đ
MakeMyBobble.in/welcome
*Create fun conversations.* Stickers, GIFs, Poptexts & more. Download Bobble Keyboard Now đ
MakeMyBobble.in/welcome
*Create fun conversations.* Stickers, GIFs, Poptexts & more. Download Bobble Keyboard Now đ
MakeMyBobble.in/welcome
*Create fun conversations.* Stickers, GIFs, Poptexts & more. Download Bobble Keyboard Now đ
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Atomic structure as applied to generation of X-rays.pptxDr. Dheeraj Kumar
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Atoms are the fundamental units of matter.
Composed of subatomic particles: protons, neutrons, and electrons.
Unique identity determined by the number of protons (atomic number).
Dynamic imaging (imaging obtained at rest, during squeezing, straining, and defecation) has a central role in the diagnosis of pelvic floor dysfunction, and it is crucial when choosing a conservative versus a surgical treatment .
Magnetic resonance (MR) imaging has an increasing role in assessing pelvic floor dysfunction because of its multiplanar imaging capability, the intrinsic soft-tissue contrast and the absence of ionizing radiation.
These features are specifically suitable for those patients with multicompartment involvement and for those who have undergone previous repairs.
This pictorial essay shows dynamic MR imaging findings in pelvic floor disorders such as prolapse, obstructed defecation, and fecal incontinence.
Safety risks include translational force and torque, projectile injury, excessive specific absorption rate, burns, peripheral neurostimulation, interactions with active implants and devices, and acoustic injury. Standards for MR imaging device safety terminology were first issued in 2005 and are required by the U.S. Food and Drug Administration, with devices labeled as âMR safe,â âMR unsafe,â or âMR conditional.â
MR imaging contrast agent safety is also discussed in this article. Additional technical and safety policies relate to pediatric, unconscious, incapacitated, or pregnant patients and pregnant imaging personnel.
Journal Club : Article by Kim YS, Rhim H, Choi MJ, Lim HK, Choi D. High-intensity focused ultrasound therapy: an overview for radiologists. Korean journal of radiology. 2008 Aug 1;9(4):291-302.
Honest Reviews of Tim Han LMA Course Program.pptxtimhan337
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Personal development courses are widely available today, with each one promising life-changing outcomes. Tim Hanâs Life Mastery Achievers (LMA) Course has drawn a lot of interest. In addition to offering my frank assessment of Success Insiderâs LMA Course, this piece examines the courseâs effects via a variety of Tim Han LMA course reviews and Success Insider comments.
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It is possible to hide or invisible some fields in odoo. Commonly using âinvisibleâ attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
A Strategic Approach: GenAI in EducationPeter Windle
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Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
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Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
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Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
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This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
2. X-ray Production
⢠The production of x-rays requires a rapidly moving stream of electrons that
are suddenly decelerated or stopped. The source of electrons is the cathode,
or negative electrode. Electrons are stopped or decelerated by the anode, or
positive electrode. Electrons move between the cathode and the anode
because there is a potential difference in charge between the electrodes.
3.
4. X ray tubes
⢠The x-ray tube produces an environment for x-ray production via
bremsstrahlung and characteristic radiation mechanisms.
Major components are the cathode, anode, rotar/stator, glass (or metal)
envelope, and tube housing .
Electrons from the cathode filament are accelerated towards the anode by a
peak voltage ranging from 20,000 to 150,000 V (20 to 150 kVp).
The tube current is the rate of electron flow from the cathode to the anode,
measured in milliamperes (mA), where 1mA = 6.24 x 10*15 electrons/sec.
5.
6. CATHODe
⢠Negatively charged electrode
⢠The source of electrons in the x ray tube is the cathode, which is a helical filament of tungsten wire
surrounded by a focusing cup.
⢠This structure is electrically connected to the filament circuit.
⢠The filament circuit provides a voltage upto about 10 V to the filament, producing a current up to
about 7 A through a filament.
⢠Electrical resistance heat the filament and releases the electrons via a process called thermionic
emission.
⢠The electrons liberated from the filament flow through the vacuum of the x ray tube, when a
positive voltage is placed on the anode with respect to the cathode.
⢠Adjustments in the filament current (and thus in the filament temperature) control the tube current.
7. ⢠A trace of the thorium in the tungsten filament increases the
efficiency of the of electron emission and prolongs filament life.
⢠The focusing cup is also called the cathode block, surrounds the
filament and shapes the electron beam width.
⢠The voltage applied to the cathode block is typically the same as
applied to the filament. This shapes the line of the electrical potential
to focus the electron beam to produce a small interaction area (focal
spot) on the anode.
⢠Although the width of the focusing cup slot determines the focal
spot width, the filament length determines the focal spot length.
⢠X ray tube has two filaments for diagnostic imaging small and large
focal spot on the target.
8. ⢠The filament current determines the filament temperature and thus the rate of the
thermoinic electron emission.
⢠As the electrical resistance to the filament current heats the filament, electrons are emitted
from its surface.
⢠When no voltage is applied between the anode and the cathode of the x ray tube, an
electron cloud, also called as space charge cloud, builds around the filament. Applying a
positive high voltage to the anode with respect to the cathode accelerates the electrons
towards the anode and produces a tube current.
⢠Small changes in the filament current can produces relatively large changes in the tube
current.
⢠The existence of the space charge cloud shields the electric field for tube voltage of 40 kVp
and lower, and only a portion of free electrons are instantaneously accelerated to the
anode. When this happens, the operation of the x-ray tube is space charge limited, which
places an upper limit on the tube current, regardless of the filament current. Above 4o kVp,
the space charge cloud effect is overcome by the applied potential difference and the tube
current is limited only by the emission of electrons from the filament. Therefore, the
filament current controls the tube current in a predictable way (emission limited operation).
9. ANODE
⢠Positively charged electrode
⢠There are two types of anodes : Stationary anode
Rotating anode
STATIONARY:
⢠The simplest type of the tube has the stationary (fixed) anode. It consist of tungsten insert imbedded in the
copper block .
⢠The copper act as a dual role: Its supports the tungsten target and it removes heat efficiently from the tungsten
target.
⢠Dental x ray unit, portable x ray machine and portable fluoroscopy systems use fixed anode x ray tube.
ROTATING:
⢠It is mostly used in the diagnostic x ray application, mainly because of their greater heat loading and
consequently higher x ray output capabilities.
⢠Electrons impart their energy on a continuously rotating target, spreading thermal energy over a large area and
a mass of the anode disc.
⢠A bearing mounted rotor assembly supports the anode disc within the evacuated x ray tube insert .
10. ⢠X ray machines are designed so that the x ray tube will not be
energized if the anode is not upto full speed, this is the cause for
the short delay (1-2 seconds) when the x ray tube exposure
button is pushed.
⢠Rotor bearings are heat sensitive and are often the cause of the
x ray tube failure. Bearings are in the high-vaccum environment
of the insert and require special heat â insensitive , non volatile
lubricants.
⢠A molybdenum stem attaches the anode to the rotor/ bearing
assembly, because molybdenum is poor heat conductor and
reduces heat transfer from the anode to the bearings. Because
it is thermally isolated, the anode must be cooled by radiative
emission.
11.
12.
13. X-rays are produced by two main mechanisms and
come in two varieties â
characteristic and bremsstrahlung
SPECTRUM
14. bremsstrahlung
⢠The conversion of electron kinetic energy into electromagnetic radiation produces x ray.
⢠A Large voltage is applied between two electrodes (the cathode and the anode) in a
evacuated envelope. The cathode is negatively charged and is the source of electrons; the
anode is positively charged and is the target of electrons. As electrons from the cathode
travel to the anode, they are accelerated by the electrical potential difference between
these electrodes and attain kinetic energy.
⢠The kinetic energy gained by an electron is proportional to the potential difference
between the cathode and anode.
⢠On impact with the target, the kinetic energy of the electrons is converted to the other
form of energy. The vast majority of interactions produce unwanted heat by small
collisional energy exchange with electrons in the target. This intense heating limits the
number of x ray photons that can be produced in a given time without destroying the
target. Occasionally an electron comes within the proximity of a positively charged
nucleus in the target electrode.
15.
16. ⢠The columbic forces attract and decelerate the electron, causing a
significant loss of kinetic energy and a change in a electronâs trajectory. An
x ray photon with energy equal to the kinetic energy lost by the electron is
produced. This radiation is termed bremsstrahlung.
⢠The subatomic distance between the bombarding electron and the nucleus
determines the energy lost by each electron during the bremsstrahlung
process because the columbic force of attraction increases with the
inverse square of the interaction distance. At relatively large distances
from the nucleus , the columbic attraction force is weak. These encounters
produce low x ray energy.
⢠For closer interaction distances the force acting on the electron increases,
causing a more dramatic change in the electronâs trajectory and a larger
loss of energy; these encounters produce high x ray energy.
⢠A direct impact of an electron with the target nucleus results in loss of all
the electronâs kinetic energy.
17. ⢠The probability of an electronâs directly impacting a nucleus is
extremely low, simply because at the atomic scale, the atom
comprises mainly empty âspaceâ and the nuclear cross section is
very small. Therefore, lower x ray energies are generated in
greater abundance , and the number of higher energy x rays
decreases approximately linearly with energy upto the maximum
energy of the incident electrons.
18.
19. characteristic
⢠Each electron in the target atom has a binding energy that depends on the shell in
which it resides.
⢠Closest to the nucleus are the two electrons in the K shell, which has the highest
binding energy. The L shell, with 8 electrons has the next highest binding energy,
and so forth.
⢠When the energy of an electron incident on the target exceeds the binding energy
of the electron of a target atom it is energetically possible for a collisional
interaction to eject the electron and ionize the atom.
⢠The unfilled shell is energetically unstable and an outer shell electron with less
binding energy will fill the vacancy. As this electron transitions to lower energy
state the excess energy can be released as a characteristic x ray photon with an
energy equal to the difference between the binding energies of the electron shell.
20. ⢠Binding energies are unique to a given element, and so their
differences; consequently the emitted x rays have discrete
energies that are characteristic of that element.
⢠Many electron transitions can occur from adjacent and non
adjacent shells in the atom, giving rise to the several discrete
energy peaks superimposed on the continuous bremsstrahlung
spectrum. The most prevalent characteristic x ray in the
diagnostic energy range result from K shell vacancies, which are
filled by electrons from the L, M N shells.
⢠Characteristic K x rays are emitted only when the electrons
impinging on the target exceeds the binding energy of the K
shell electron.
25. ⢠Its supports the tungsten target and it removes heat efficiently
from the tungsten target.
Editor's Notes
K shell â higher binding energy
The electron interacts with the k shell e- via a repulsive electrical force ----the k shell e- is removed( the energy of e- is > k shell binding energy.------leaving a vacancy in the k shell
----.----The unfilled shell is unstable and an outer shell electron with less binding energy will fill the vacancy------an e- from the adjacent l shell fills the vacancy
-----energy can be released as a characteristic x ray photon with an energy equal to the difference between the binding energies of the electron shell.