The document discusses the line focus principle, which involves angling the anode surface to reduce the effective focal spot size while allowing greater heat dissipation across the actual focal spot. It also describes the anode heel effect, where x-ray intensity is lower on the anode side due to greater absorption of radiation as it passes through the thicker portion of the angled anode. Applications of the anode heel effect include positioning the thicker part of the anatomy toward the cathode side for more uniform exposure during radiography.
Production of x rays
Components of X-ray
Cathode
kVp , mA , mAs .
Line focus principle
Heel effect
anode
Stationary anode x ray tube
Rotating anode x-ray tube
Grid controlled x-ray tube
Saturation voltage
Metal ceramic x – ray tube
Processes of x- ray generation
intensity of the x-ray beams
Effect of kVp on x- ray beam
Effect of tube current on x- ray beam
learn with Me...........MK
if you notice any mistake comment please ......
The line focus principle helps resolve the issue of needing a small focal spot for good image quality while also needing a large focal spot to protect the tungsten target from heat accumulation. It works by mounting the target at an angled position, so that the apparent or effective focal spot size seen from the position of the film is smaller than the actual focal spot size. The effective focal spot size can be calculated as the actual focal spot size multiplied by the sine of the anode angle. This allows heat to dissipate over a larger area while maintaining a small focal spot for image sharpness. A limitation is the anode heel effect caused by non-uniform radiation from different parts of the angled anode surface. The target angle
X-ray spectrum , target material , factors affecting x-ray beam.pptxgorit61868
The document discusses factors that affect x-ray emission spectra. It explains that x-ray intensity depends on target material (Z), tube potential (kVp), and tube current (mA). Tungsten is used as the target material due to its high melting point, atomic number, and thermal conductivity. The space charge effect and saturation voltage impact emission, with the former limiting electron emission and the latter relating potential to electron pull-away. The anode heel effect produces lower intensity toward the anode due to absorption. The line focus principle uses angled targets to make the effective focal spot smaller than the actual interaction area, improving image quality while allowing heat dissipation.
This document provides an overview of how X-rays are produced in an X-ray tube. It describes the key components of an X-ray tube, including the glass enclosure, cathode, anode, and how they work together. The cathode emits electrons via thermionic emission when heated. These electrons are accelerated towards the anode and decelerate upon impact, producing X-rays. Higher kVp results in more energetic X-rays while higher mA results in more electrons and thus more X-rays. Rotating and stationary anodes aim to dissipate heat from electron bombardment and allow higher outputs.
X-rays are produced when fast moving electrons are decelerated upon impact with a metal target in an x-ray tube. The x-ray tube contains a cathode that emits electrons via thermionic emission when heated, and an anode target. Vacuum is necessary to allow electron acceleration and control. Rotating or stationary anode designs improve heat dissipation during x-ray production. Grid controlled tubes allow rapid on/off switching of the electron beam and x-ray output.
The document discusses the working principle of scanning electron microscopy (SEM). It describes how SEM uses a focused beam of electrons to scan the surface of a sample to produce images. SEM provides higher resolution than light microscopes due to the much shorter wavelength of electrons. The document outlines the various components of an SEM, including the electron gun, electromagnetic lenses, detectors for secondary electrons and backscattered electrons, and how these are used to control magnification and resolution. It also discusses some imaging parameters and artifacts that can influence SEM results.
The document discusses x-ray production in an x-ray tube. It describes the three essentials needed - an electron source, means of acceleration, and a target for impact. Modern tubes use a tungsten filament as the electron source, which is heated to emit electrons. A high voltage is applied to accelerate electrons toward the anode target. Upon impact, a small portion of the kinetic energy is converted to x-rays. Rotating anodes and various cooling methods allow higher outputs by dissipating heat.
The document discusses x-ray production in an x-ray tube. It describes the three essentials needed - an electron source, means of acceleration, and a target for impact. Modern tubes use a tungsten filament as the electron source, which is heated to emit electrons. A high voltage is applied to accelerate electrons toward the anode target. Upon impact, a small portion of the kinetic energy is converted to x-rays. Rotating anodes and various cooling methods allow higher outputs by dissipating heat.
Production of x rays
Components of X-ray
Cathode
kVp , mA , mAs .
Line focus principle
Heel effect
anode
Stationary anode x ray tube
Rotating anode x-ray tube
Grid controlled x-ray tube
Saturation voltage
Metal ceramic x – ray tube
Processes of x- ray generation
intensity of the x-ray beams
Effect of kVp on x- ray beam
Effect of tube current on x- ray beam
learn with Me...........MK
if you notice any mistake comment please ......
The line focus principle helps resolve the issue of needing a small focal spot for good image quality while also needing a large focal spot to protect the tungsten target from heat accumulation. It works by mounting the target at an angled position, so that the apparent or effective focal spot size seen from the position of the film is smaller than the actual focal spot size. The effective focal spot size can be calculated as the actual focal spot size multiplied by the sine of the anode angle. This allows heat to dissipate over a larger area while maintaining a small focal spot for image sharpness. A limitation is the anode heel effect caused by non-uniform radiation from different parts of the angled anode surface. The target angle
X-ray spectrum , target material , factors affecting x-ray beam.pptxgorit61868
The document discusses factors that affect x-ray emission spectra. It explains that x-ray intensity depends on target material (Z), tube potential (kVp), and tube current (mA). Tungsten is used as the target material due to its high melting point, atomic number, and thermal conductivity. The space charge effect and saturation voltage impact emission, with the former limiting electron emission and the latter relating potential to electron pull-away. The anode heel effect produces lower intensity toward the anode due to absorption. The line focus principle uses angled targets to make the effective focal spot smaller than the actual interaction area, improving image quality while allowing heat dissipation.
This document provides an overview of how X-rays are produced in an X-ray tube. It describes the key components of an X-ray tube, including the glass enclosure, cathode, anode, and how they work together. The cathode emits electrons via thermionic emission when heated. These electrons are accelerated towards the anode and decelerate upon impact, producing X-rays. Higher kVp results in more energetic X-rays while higher mA results in more electrons and thus more X-rays. Rotating and stationary anodes aim to dissipate heat from electron bombardment and allow higher outputs.
X-rays are produced when fast moving electrons are decelerated upon impact with a metal target in an x-ray tube. The x-ray tube contains a cathode that emits electrons via thermionic emission when heated, and an anode target. Vacuum is necessary to allow electron acceleration and control. Rotating or stationary anode designs improve heat dissipation during x-ray production. Grid controlled tubes allow rapid on/off switching of the electron beam and x-ray output.
The document discusses the working principle of scanning electron microscopy (SEM). It describes how SEM uses a focused beam of electrons to scan the surface of a sample to produce images. SEM provides higher resolution than light microscopes due to the much shorter wavelength of electrons. The document outlines the various components of an SEM, including the electron gun, electromagnetic lenses, detectors for secondary electrons and backscattered electrons, and how these are used to control magnification and resolution. It also discusses some imaging parameters and artifacts that can influence SEM results.
The document discusses x-ray production in an x-ray tube. It describes the three essentials needed - an electron source, means of acceleration, and a target for impact. Modern tubes use a tungsten filament as the electron source, which is heated to emit electrons. A high voltage is applied to accelerate electrons toward the anode target. Upon impact, a small portion of the kinetic energy is converted to x-rays. Rotating anodes and various cooling methods allow higher outputs by dissipating heat.
The document discusses x-ray production in an x-ray tube. It describes the three essentials needed - an electron source, means of acceleration, and a target for impact. Modern tubes use a tungsten filament as the electron source, which is heated to emit electrons. A high voltage is applied to accelerate electrons toward the anode target. Upon impact, a small portion of the kinetic energy is converted to x-rays. Rotating anodes and various cooling methods allow higher outputs by dissipating heat.
Filters used in radiology.ppt.radiology.Arya Prasad
Filters and grids are used in radiography to improve image quality. Filters shape the x-ray beam by absorbing lower energy photons. There are inherent filters from the x-ray tube and added filters like aluminum and copper sheets. Grids reduce scatter radiation using lead foil strips separated by spacers. Higher ratio grids provide better contrast but also increase patient dose. Factors like primary transmission, Bucky factor and contrast improvement factor evaluate grid performance. Positioning errors can cause grid cutoff where parts of the image are lighter. Air gaps also reduce scatter by increasing the distance radiation travels through the patient.
X-ray tubes produce x-rays when a stream of electrons, generated by a heated cathode filament, strikes a metal anode target. The cathode produces electrons through thermionic emission when heated to high temperatures. These electrons are accelerated towards the anode, where 1% of their kinetic energy is converted to x-ray photons upon impact, while 99% is dissipated as heat. Modern x-ray tubes use a rotating anode target to spread the heat over a large surface area and prevent damage. Tungsten is commonly used for the anode and cathode due to its high melting point and resistance to vaporization.
1) The document discusses the components and functioning of an x-ray tube, including the cathode, thermionic emission, space charge effect, focussing cup, anode, and grid control.
2) It describes how increasing the voltage across the x-ray tube increases the kinetic energy of electrons, producing x-rays via bremsstrahlung and characteristic radiation processes.
3) Rotating and stationary anodes are discussed as ways to dissipate heat generated during x-ray production and allow higher power outputs from the tube.
Beam restriction refers to decreasing the size of the projected x-ray field to limit unnecessary radiation exposure and reduce scattered radiation. This improves image quality by increasing radiographic contrast. Common beam restricting devices include aperture diaphragms, cones, cylinders, and collimators. Collimators allow adjustable rectangular or square field sizes and include lights and templates to ensure accurate beam alignment. Proper collimation is important for patient safety and diagnostic image quality.
CONTENTS
Electron arc therapy.
Introduction to electron arc therapy
Calibration of electron arc therapy
field shaping
beam energy
Treatment planning
location of the isocentre
scanning field width
collimation used in electron arc therapy.
summary
Measurement of optical fiber refractive indexCKSunith1
The attached narrated power point presentation discusses the various methods for measurement of refractive index of an optical fiber. The material will be useful for KTU final year B Tech students who prepare for the subject EC 405, Optical Communications.
1. A current is passed through the tungsten filament to heat it up via thermionic emission and release electrons.
2. The electrons are accelerated towards the positively charged anode by the tube voltage and interact with the anode material, primarily releasing x-ray photons via Bremsstrahlung and characteristic interactions.
3. The resulting x-ray beam exits the tube and passes through the patient to form an x-ray image.
1. X-rays are produced when fast moving electrons are decelerated upon striking a metal target in an x-ray tube.
2. Modern x-ray tubes use a tungsten target and operate under vacuum to allow for control of the electron beam and prevent degradation of the tube.
3. X-ray output is determined by tube voltage (kVp), current (mAs), and filtration - with higher kVp and mAs producing higher quality and quantity respectively.
Updates on Electron Beam Therapy
I) Introduction
II) Central Axis Depth dose distribution
III) Dosimetric parametrics of electron beam
IV) Clinical Considerations of Electron beam therapy
1. Isodose curves represent the dose distribution from radiation beams and are lines connecting points of equal percentage depth dose. They are used to depict the volumetric and planar variations in absorbed dose.
2. The parameters that affect the shape of isodose curves include beam quality, source size, SSD, SDD, field size, and beam modifiers like wedges and flattening filters. Lower beam energy results in greater lateral scatter and more bulging curves.
3. Multiple radiation fields can be combined using appropriate beam weights, sizes, angles and modifiers to deliver a more uniform dose to the tumor while sparing surrounding tissues. Parameters like setup accuracy and plan practicality are also considered.
The document summarizes key aspects of radiographic grids used to reduce scatter radiation in x-ray imaging. It describes the components and invention of grids, different grid patterns like linear and focused grids, as well as factors that affect grid performance such as grid ratio and lines per inch. Methods for evaluating grids like primary transmission, Bucky factor and contrast improvement are also outlined. Potential issues with grid use involving cutoff and decentering are discussed.
This document provides an overview of the working principle of a scanning electron microscope (SEM). It discusses key components of an SEM like the electron gun, condenser lenses, scan coils, objective lens, and detectors. It explains how SEM produces high-resolution images by scanning a focused beam of electrons across a sample. Secondary electrons and backscattered electrons are generated from sample-electron interactions and detected to form images. Factors affecting resolution, magnification and other imaging modes are also summarized. Advantages of SEM like high resolution and versatility are mentioned along with disadvantages like high cost, vacuum requirements and sample preparation needs.
This document provides an overview of x-ray production. It discusses how x-rays are produced through interactions between electrons and heavy atomic number targets. It describes the discovery of x-rays by Roentgen in 1895 and some key properties. The document then explains the basic processes of bremsstrahlung and characteristic x-ray production in more detail. It also discusses x-ray tube design components like the cathode, anode, vacuum, and housing needed to generate x-rays.
X-rays are produced when fast moving electrons are decelerated upon impact with the target anode of an x-ray tube. The x-ray tube contains a cathode that emits electrons and a stationary or rotating anode target. When electrons collide with the anode, x-rays are produced via two processes: characteristic radiation from electron shell interactions and continuous bremsstrahlung radiation from deflected electrons. Additional components such as filters and housing manage heat dissipation and focus the x-ray beam for medical imaging applications.
This document discusses the key factors that control an x-ray beam, including exposure time, tube current, tube voltage, filtration, collimation, source-to-film distance, and target material. It explains how each factor affects the quantity and quality of the x-ray beam by influencing the number of photons generated, their mean energy and maximum energy. The document provides details on how varying these technical parameters can optimize radiographic image quality while maintaining patient safety.
The document summarizes key aspects of radiographic grids used to reduce scatter radiation in x-ray imaging. It describes the components and design of grids, including the lead and spacer materials, grid ratios, patterns (linear, crossed, focused, parallel), and lines per inch. Methods for characterizing grid performance like primary transmission, Bucky factor, and contrast improvement factor are also outlined. Potential issues like cutoff, decentering, and vibration are discussed, as well as the tradeoff between reduced scatter and increased patient dose with higher ratio grids.
This document provides an overview of x-ray imaging techniques. It describes what x-rays are and how they are generated within an x-ray machine. X-rays are generated when high-voltage electrons collide with a metal target, such as tungsten. This causes the electrons to lose energy and emit x-ray photons. The x-ray machine contains an x-ray tube, high voltage generator, and control console to produce x-rays and control their intensity and energy. X-rays can pass through soft tissues but are absorbed by denser bones, allowing x-ray images to reveal internal body structures.
Wilhelm Roentgen discovered X-rays in 1895 while experimenting with cathode ray tubes. He noticed fluorescent screens glowing in a darkened room when a high voltage was applied to the tube. This led to the discovery that X-rays could pass through and image bones in the human body. Modern X-ray tubes use a tungsten target bombarded by electrons emitted from a heated filament to produce X-rays, which are used in medical imaging and radiation therapy. X-rays are generated via two mechanisms: bremsstrahlung and characteristic radiation.
This document provides a history of scientific models of atoms from ancient Greek philosophers to modern particle physics. It summarizes key developments including:
1) Dalton's atomic theory proposed that all matter is composed of indivisible atoms in definite proportions.
2) Rutherford's gold foil experiment led to the discovery of the nucleus and a "planetary" model of electrons orbiting the nucleus.
3) Bohr incorporated quantum theory to explain atomic spectra, proposing electrons orbit in discrete energy levels.
4) The discovery of subatomic particles like electrons, protons, and neutrons led to the modern view of atoms and their composition.
This document provides an overview of ultrasound principles and instrumentation. It begins by explaining that ultrasound uses high frequency sound waves between 2-20 MHz to produce images of internal structures. The key components of an ultrasound machine include a piezoelectric crystal transducer that emits sound waves and receives echoes to create images, displayed on a monitor. The document then discusses ultrasound physics concepts such as reflection, refraction, scattering and attenuation of sound waves in tissues. It also covers ultrasound imaging modes, transducer types, common applications and advantages/disadvantages of the modality.
More Related Content
Similar to anodeheeleffectlinefocusprinciple-200816152731.pdf
Filters used in radiology.ppt.radiology.Arya Prasad
Filters and grids are used in radiography to improve image quality. Filters shape the x-ray beam by absorbing lower energy photons. There are inherent filters from the x-ray tube and added filters like aluminum and copper sheets. Grids reduce scatter radiation using lead foil strips separated by spacers. Higher ratio grids provide better contrast but also increase patient dose. Factors like primary transmission, Bucky factor and contrast improvement factor evaluate grid performance. Positioning errors can cause grid cutoff where parts of the image are lighter. Air gaps also reduce scatter by increasing the distance radiation travels through the patient.
X-ray tubes produce x-rays when a stream of electrons, generated by a heated cathode filament, strikes a metal anode target. The cathode produces electrons through thermionic emission when heated to high temperatures. These electrons are accelerated towards the anode, where 1% of their kinetic energy is converted to x-ray photons upon impact, while 99% is dissipated as heat. Modern x-ray tubes use a rotating anode target to spread the heat over a large surface area and prevent damage. Tungsten is commonly used for the anode and cathode due to its high melting point and resistance to vaporization.
1) The document discusses the components and functioning of an x-ray tube, including the cathode, thermionic emission, space charge effect, focussing cup, anode, and grid control.
2) It describes how increasing the voltage across the x-ray tube increases the kinetic energy of electrons, producing x-rays via bremsstrahlung and characteristic radiation processes.
3) Rotating and stationary anodes are discussed as ways to dissipate heat generated during x-ray production and allow higher power outputs from the tube.
Beam restriction refers to decreasing the size of the projected x-ray field to limit unnecessary radiation exposure and reduce scattered radiation. This improves image quality by increasing radiographic contrast. Common beam restricting devices include aperture diaphragms, cones, cylinders, and collimators. Collimators allow adjustable rectangular or square field sizes and include lights and templates to ensure accurate beam alignment. Proper collimation is important for patient safety and diagnostic image quality.
CONTENTS
Electron arc therapy.
Introduction to electron arc therapy
Calibration of electron arc therapy
field shaping
beam energy
Treatment planning
location of the isocentre
scanning field width
collimation used in electron arc therapy.
summary
Measurement of optical fiber refractive indexCKSunith1
The attached narrated power point presentation discusses the various methods for measurement of refractive index of an optical fiber. The material will be useful for KTU final year B Tech students who prepare for the subject EC 405, Optical Communications.
1. A current is passed through the tungsten filament to heat it up via thermionic emission and release electrons.
2. The electrons are accelerated towards the positively charged anode by the tube voltage and interact with the anode material, primarily releasing x-ray photons via Bremsstrahlung and characteristic interactions.
3. The resulting x-ray beam exits the tube and passes through the patient to form an x-ray image.
1. X-rays are produced when fast moving electrons are decelerated upon striking a metal target in an x-ray tube.
2. Modern x-ray tubes use a tungsten target and operate under vacuum to allow for control of the electron beam and prevent degradation of the tube.
3. X-ray output is determined by tube voltage (kVp), current (mAs), and filtration - with higher kVp and mAs producing higher quality and quantity respectively.
Updates on Electron Beam Therapy
I) Introduction
II) Central Axis Depth dose distribution
III) Dosimetric parametrics of electron beam
IV) Clinical Considerations of Electron beam therapy
1. Isodose curves represent the dose distribution from radiation beams and are lines connecting points of equal percentage depth dose. They are used to depict the volumetric and planar variations in absorbed dose.
2. The parameters that affect the shape of isodose curves include beam quality, source size, SSD, SDD, field size, and beam modifiers like wedges and flattening filters. Lower beam energy results in greater lateral scatter and more bulging curves.
3. Multiple radiation fields can be combined using appropriate beam weights, sizes, angles and modifiers to deliver a more uniform dose to the tumor while sparing surrounding tissues. Parameters like setup accuracy and plan practicality are also considered.
The document summarizes key aspects of radiographic grids used to reduce scatter radiation in x-ray imaging. It describes the components and invention of grids, different grid patterns like linear and focused grids, as well as factors that affect grid performance such as grid ratio and lines per inch. Methods for evaluating grids like primary transmission, Bucky factor and contrast improvement are also outlined. Potential issues with grid use involving cutoff and decentering are discussed.
This document provides an overview of the working principle of a scanning electron microscope (SEM). It discusses key components of an SEM like the electron gun, condenser lenses, scan coils, objective lens, and detectors. It explains how SEM produces high-resolution images by scanning a focused beam of electrons across a sample. Secondary electrons and backscattered electrons are generated from sample-electron interactions and detected to form images. Factors affecting resolution, magnification and other imaging modes are also summarized. Advantages of SEM like high resolution and versatility are mentioned along with disadvantages like high cost, vacuum requirements and sample preparation needs.
This document provides an overview of x-ray production. It discusses how x-rays are produced through interactions between electrons and heavy atomic number targets. It describes the discovery of x-rays by Roentgen in 1895 and some key properties. The document then explains the basic processes of bremsstrahlung and characteristic x-ray production in more detail. It also discusses x-ray tube design components like the cathode, anode, vacuum, and housing needed to generate x-rays.
X-rays are produced when fast moving electrons are decelerated upon impact with the target anode of an x-ray tube. The x-ray tube contains a cathode that emits electrons and a stationary or rotating anode target. When electrons collide with the anode, x-rays are produced via two processes: characteristic radiation from electron shell interactions and continuous bremsstrahlung radiation from deflected electrons. Additional components such as filters and housing manage heat dissipation and focus the x-ray beam for medical imaging applications.
This document discusses the key factors that control an x-ray beam, including exposure time, tube current, tube voltage, filtration, collimation, source-to-film distance, and target material. It explains how each factor affects the quantity and quality of the x-ray beam by influencing the number of photons generated, their mean energy and maximum energy. The document provides details on how varying these technical parameters can optimize radiographic image quality while maintaining patient safety.
The document summarizes key aspects of radiographic grids used to reduce scatter radiation in x-ray imaging. It describes the components and design of grids, including the lead and spacer materials, grid ratios, patterns (linear, crossed, focused, parallel), and lines per inch. Methods for characterizing grid performance like primary transmission, Bucky factor, and contrast improvement factor are also outlined. Potential issues like cutoff, decentering, and vibration are discussed, as well as the tradeoff between reduced scatter and increased patient dose with higher ratio grids.
This document provides an overview of x-ray imaging techniques. It describes what x-rays are and how they are generated within an x-ray machine. X-rays are generated when high-voltage electrons collide with a metal target, such as tungsten. This causes the electrons to lose energy and emit x-ray photons. The x-ray machine contains an x-ray tube, high voltage generator, and control console to produce x-rays and control their intensity and energy. X-rays can pass through soft tissues but are absorbed by denser bones, allowing x-ray images to reveal internal body structures.
Wilhelm Roentgen discovered X-rays in 1895 while experimenting with cathode ray tubes. He noticed fluorescent screens glowing in a darkened room when a high voltage was applied to the tube. This led to the discovery that X-rays could pass through and image bones in the human body. Modern X-ray tubes use a tungsten target bombarded by electrons emitted from a heated filament to produce X-rays, which are used in medical imaging and radiation therapy. X-rays are generated via two mechanisms: bremsstrahlung and characteristic radiation.
Similar to anodeheeleffectlinefocusprinciple-200816152731.pdf (20)
This document provides a history of scientific models of atoms from ancient Greek philosophers to modern particle physics. It summarizes key developments including:
1) Dalton's atomic theory proposed that all matter is composed of indivisible atoms in definite proportions.
2) Rutherford's gold foil experiment led to the discovery of the nucleus and a "planetary" model of electrons orbiting the nucleus.
3) Bohr incorporated quantum theory to explain atomic spectra, proposing electrons orbit in discrete energy levels.
4) The discovery of subatomic particles like electrons, protons, and neutrons led to the modern view of atoms and their composition.
This document provides an overview of ultrasound principles and instrumentation. It begins by explaining that ultrasound uses high frequency sound waves between 2-20 MHz to produce images of internal structures. The key components of an ultrasound machine include a piezoelectric crystal transducer that emits sound waves and receives echoes to create images, displayed on a monitor. The document then discusses ultrasound physics concepts such as reflection, refraction, scattering and attenuation of sound waves in tissues. It also covers ultrasound imaging modes, transducer types, common applications and advantages/disadvantages of the modality.
This document provides an overview of common pathologies that can be identified on ultrasound of the female pelvis. It describes normal ultrasound anatomy and then discusses congenital uterine anomalies, endometrial disorders, ovarian cysts and neoplasms, and pelvic inflammatory disease. For each condition, it provides a brief description and ultrasound appearance. The goal is to describe the most frequent pelvic pathologies seen on ultrasound and enable identification of various conditions.
This document presents an assessment of hysterosalpingography findings among women of reproductive age at a center in Cameroon. It includes an introduction on hysterosalpingography and infertility rates in sub-Saharan Africa. The study aims to understand hysterosalpingography indications and diagnoses in Cameroon. A total of 43 women underwent hysterosalpingography. The results show the majority were aged 26-35 (34.9%), married (79.1%), and diagnosed with primary infertility (58%). Abnormal findings were most commonly related to the fallopian tubes (69.7%). The most frequent diagnoses were tubal occlusion (21.4%) and uterine synechiae (
Bladder cancer begins in the cells lining the bladder. It is most common in the urothelial cells. The main types are urothelial carcinoma, squamous cell carcinoma, adenocarcinoma, and small cell carcinoma. Risk factors include smoking, chemical exposure, infections, and genetic factors. Symptoms include blood in the urine, pain during urination, and frequent urges to urinate. Diagnosis involves cystoscopy, urine tests, imaging, and biopsy. Treatment depends on cancer stage and invasiveness, and may include surgery, chemotherapy, immunotherapy, and radiation. Side effects vary by treatment but can include incontinence, infertility, fatigue, and pain.
This document discusses the dual wave-particle nature of X-rays and their interaction with matter. It notes that X-rays can behave as both waves that propagate through space, as well as particles called photons. The key interactions discussed are photoelectric effect, Compton scattering, and pair production.
The photoelectric effect results in a photon being absorbed by an atom, ejecting an electron and leaving the atom ionized. Compton scattering involves a photon ejecting an electron from an atom but also being deflected and losing some energy. Pair production occurs when a photon interacts near the nucleus of an atom and transforms into an electron-positron pair.
When x-rays enter the body, they interact at the atomic level to cause ionization. Radiobiology examines the response of living systems to ionizing radiation. Ionization occurs when an electron is removed from an atom, creating a positively-charged ion. X-rays and gamma rays are electromagnetic radiation that can ionize tissues, while particulate radiation like alpha particles and electrons have mass and readily interact. Ionizing radiation can damage cells through direct interaction or production of free radicals via indirect interaction with water molecules, potentially causing cell death or mutation. The biological effects of radiation depend on several factors like total dose, dose rate, and cell radiosensitivity.
X-rays are a form of ionizing radiation that produces charged particles when passing through matter. The goals of radiation protection are to protect persons from both short-term and long-term effects of radiation by adhering to an established radiation protection program. Effective radiation protection employs measures to safeguard patients, personnel, and the public from unnecessary radiation exposure.
This document discusses x-rays, including their production via decelerating charges in an x-ray tube, their spectrum determined by the target atom type, and common x-ray sources like sealed tubes and synchrotrons. It also covers beam conditioning techniques like collimation, monochromatization using beta filters or crystal monochromators, and factors that affect monochromator performance like reflectivity and resolution.
This document discusses principles of radiation protection including justification, optimization, and dose limits. It describes how justification requires that the benefits of any radiation exposure outweigh the risks, and optimization aims to keep radiation exposure as low as reasonably achievable. Various personnel protective devices are described such as lead aprons, gloves, glasses and gonad shields that can reduce radiation exposure. The document emphasizes applying principles of time, distance and shielding to minimize dose and ensuring radiation practices are justified.
This document provides an overview of radiation protection principles in nuclear medicine based on a chapter from an IAEA publication. It discusses key topics including:
- The ICRP system of radiation protection including principles of justification, optimization and dose limitation.
- Radiation protection quantities such as equivalent dose, effective dose and committed dose quantities.
- Operational quantities used for radiation monitoring like ambient dose equivalent and personal dose equivalent.
- International safety standards established by organizations like the IAEA, ICRP and UNSCEAR which are based on balancing radiation risks and benefits.
The document outlines the radiation protection framework and considerations for ensuring safe use of radiation in nuclear medicine facilities.
Osteoporosis - Definition , Evaluation and Management .pdfJim Jacob Roy
Osteoporosis is an increasing cause of morbidity among the elderly.
In this document , a brief outline of osteoporosis is given , including the risk factors of osteoporosis fractures , the indications for testing bone mineral density and the management of osteoporosis
Mercurius is named after the roman god mercurius, the god of trade and science. The planet mercurius is named after the same god. Mercurius is sometimes called hydrargyrum, means ‘watery silver’. Its shine and colour are very similar to silver, but mercury is a fluid at room temperatures. The name quick silver is a translation of hydrargyrum, where the word quick describes its tendency to scatter away in all directions.
The droplets have a tendency to conglomerate to one big mass, but on being shaken they fall apart into countless little droplets again. It is used to ignite explosives, like mercury fulminate, the explosive character is one of its general themes.
Travel Clinic Cardiff: Health Advice for International TravelersNX Healthcare
Travel Clinic Cardiff offers comprehensive travel health services, including vaccinations, travel advice, and preventive care for international travelers. Our expert team ensures you are well-prepared and protected for your journey, providing personalized consultations tailored to your destination. Conveniently located in Cardiff, we help you travel with confidence and peace of mind. Visit us: www.nxhealthcare.co.uk
These lecture slides, by Dr Sidra Arshad, offer a simplified look into the mechanisms involved in the regulation of respiration:
Learning objectives:
1. Describe the organisation of respiratory center
2. Describe the nervous control of inspiration and respiratory rhythm
3. Describe the functions of the dorsal and respiratory groups of neurons
4. Describe the influences of the Pneumotaxic and Apneustic centers
5. Explain the role of Hering-Breur inflation reflex in regulation of inspiration
6. Explain the role of central chemoreceptors in regulation of respiration
7. Explain the role of peripheral chemoreceptors in regulation of respiration
8. Explain the regulation of respiration during exercise
9. Integrate the respiratory regulatory mechanisms
10. Describe the Cheyne-Stokes breathing
Study Resources:
1. Chapter 42, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 36, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 13, Human Physiology by Lauralee Sherwood, 9th edition
8 Surprising Reasons To Meditate 40 Minutes A Day That Can Change Your Life.pptxHolistified Wellness
We’re talking about Vedic Meditation, a form of meditation that has been around for at least 5,000 years. Back then, the people who lived in the Indus Valley, now known as India and Pakistan, practised meditation as a fundamental part of daily life. This knowledge that has given us yoga and Ayurveda, was known as Veda, hence the name Vedic. And though there are some written records, the practice has been passed down verbally from generation to generation.
Travel vaccination in Manchester offers comprehensive immunization services for individuals planning international trips. Expert healthcare providers administer vaccines tailored to your destination, ensuring you stay protected against various diseases. Conveniently located clinics and flexible appointment options make it easy to get the necessary shots before your journey. Stay healthy and travel with confidence by getting vaccinated in Manchester. Visit us: www.nxhealthcare.co.uk
DECLARATION OF HELSINKI - History and principlesanaghabharat01
This SlideShare presentation provides a comprehensive overview of the Declaration of Helsinki, a foundational document outlining ethical guidelines for conducting medical research involving human subjects.
Adhd Medication Shortage Uk - trinexpharmacy.comreignlana06
The UK is currently facing a Adhd Medication Shortage Uk, which has left many patients and their families grappling with uncertainty and frustration. ADHD, or Attention Deficit Hyperactivity Disorder, is a chronic condition that requires consistent medication to manage effectively. This shortage has highlighted the critical role these medications play in the daily lives of those affected by ADHD. Contact : +1 (747) 209 – 3649 E-mail : sales@trinexpharmacy.com
share - Lions, tigers, AI and health misinformation, oh my!.pptxTina Purnat
• Pitfalls and pivots needed to use AI effectively in public health
• Evidence-based strategies to address health misinformation effectively
• Building trust with communities online and offline
• Equipping health professionals to address questions, concerns and health misinformation
• Assessing risk and mitigating harm from adverse health narratives in communities, health workforce and health system
1. Anode heel effect, Line focus
principle, Off focus radiation and
its clinical applications
Soni Nagarkoti
B.Sc.MIT 2nd Year
NAMS, Bir Hospital
2. Overview
• Review of xray tube
• Production of xrays
• Effective and actual focal spot
• Line focus principle
• Anode heel effect
• Off focus radiation
• Clinical applications
4. Xray tube
• An X-ray tube is a vacuum tube.
Contains a pair of electrodes i.e. a Cathode and an
Anode.
Cathode is a filament that releases electrons when
high voltage is applied.
Anode is made up of tungsten, which attracts the
electrons.
When the electrons released from the cathode
come in contact with the tungsten , they release
energy in the form of x-ray photons.
6. Cathode component
• Negative electrode of xray tube
• Made up of filament, connecting wires and
focusing cup
• Filament is made up of tungsten that is the
source of electron
• Connecting wires is used to supply voltage and
electron to filament
• Focusing cup focuses electron to the anode
7. • Nowadays two filaments are used in xray tube
that gives rise to the two focal spots i.e.
1. Small focus
electron beam strikes small portion of
target and gives improved resolution and used in
maammo
1. Large anode
electron beam strikes larger portion of the
target and used in general radiography
8. Anode component
• Positive electron of the xray tube
• Made up of target (focal spot) and cylindrical
cu block or tungsten Rhenium disk.
• Made up of a small plate of tungsten 2 or 3mm
thick that is embedded in a large mass of cu.
• anode is generally angled at 15-20 deg.
• Could be stationary or rotating type
11. Focal spot
• It is the area actually bombarded by the
electron stream on the target.
• It can be larger or smaller in size.
• A small focal spot is required for producing
good radiographic detail but it may also lead to
overheating of target.
• Whereas large focal spot allows greater heat
loading but doesn't produce sharp image.
• This problem was solved in 1918 by the
development of line focus principle .
12. Actual focal spot
• the area of the target material being
bombarded by electrons from the filament
• Depends on the filament size and dimension of
the focusing cup
13. Effective focal spot
• the imaginary geometric line that can be drawn
based on the actual focal spot size vs. the angle
of the anode i.e. is the beam projected onto the
patient
• Depends on anode angle and actual focal spot
14.
15. • Apparent (effective) focal spot is determined
by the sine of the angle of the anode surface
• Apparent focal spot = real focal spot * sinѲ
(where Ѳ varies from 6 to 20 degrees depending
on variety of tube)
16. Line focus principle
• explains the relationship between
the anode surface and the effective focal spot size
• It states that as the anode angle is made small, the
apparent focal spot also becomes small but with
increased heat loading.
• Acccording to this, by angling the target, effective
area of the target is made much smaller that the
actual area of electron interaction
17. Basic concept of line focus principle
• During xray production, heat is dissipiated
uniformly across the focal spot and anode surface
• So large focal spot is useful to protect tungsten
from melting as heat is accumulated and
dissipated within area of focal spot
• However, a small focal spot is required to achieve
good radiographic image
• So line focus principle is important which states
that angulation of anode surface results in
apparent decrease in focal spot size
18. • for a given apparent focal spot size, the real area
covered by the electron beam is larger for smaller
target angles which, as stated above allows a
greater area over which to dissipate the heat.
• for a smaller target angle, the area covered by the
x-ray beam will be smaller so it is not possible to
cover large areas at smaller FFDs
• therefore it can be appreciated that choice of
target angle is a compromise between tube
loading, geometric unsharpness and desired area
to be covered by the useful beam
• For eg, at 40" FFD the anode angle should be no
smaller than 15 degrees.
19.
20. Relationship between apparent and real
focal spot
• -DIRECT relationship
-the SMALLER the actual focal spot, the
SMALLER the effective focal spot
-the LARGER the actual focal spot, the
LARGER the effective focal spot size
-large actual focal spot will have less heat on
the anode, than a small focal spot (same
quantity of photons over a larger area vs a
smaller area)
21.
22. Relationship between effective focal
spot and tube angle
• As anode angle increases effective focal spot
size also increases for the same actual focal
spot
• Larger tube angle will have large effective
focal spot so the tube angle should be chosen
properly so that there wont be compromising
in the resolution of the image.
23.
24. Advantages of line focus principle
• This slope allows x-rays produced at focal spot
to leave the tube sideways In such a way that
the x-ray beam emerges at right angle to the
long axis of the x-ray tube.
• It permits large area for electron bombardment
and a small x-ray source. more heat loading
with good radiographic detail.
• Sin 6⁰= 0.104
• Sin 21⁰=0.358
25. Disadvantages of line focus principle
• Anode heel effect
• Area covered by the beam reduces with the
target angle i.e.
To cover 17” the angle must be 12 degree
To cover 36” the angle must be 14 degree
26. Anode heel effect
• The intensity of the x ray beam as it leaves the
x ray tube is not uniform throughout all
portions of the beam.
• The intensity of the beam depends on the
angle at which the x rays are emitted from the
focal spot .
• The intensity of the film exposure on the anode
side of the x ray tube is less than that on the
cathode side of the tube.
27. • is one unfortunate consequence of the line-
focus principle is that the radiation intensity on
the cathode side of the x-ray field is greater
than that on the anode side
• Electrons interact with target atoms at various
depths into the target.
• The intensity of x-rays that are emitted through
the “heel” of the target is reduced because they
have a longer path through the target, and
therefore increased absorption. This is the heel
effect
28. • The x-rays that constitute the useful beam
emitted toward the anode side must deal with a
greater thickness of target material than the x-
rays emitted toward the cathode direction
• The decreased intensity of the x ray beam that
is emitted more nearly parallel to the surface of
the angled target is caused by the absorption of
some of the x ray photons by the target itself
29. • The difference in radiation intensity across the
useful beam of an x-ray field can vary by as
much as 45%.
• The central ray of the useful beam is the
imaginary line generated by the centermost x-
ray in the beam.
• If the radiation intensity along the central ray
is designated as 100%, then the intensity on
the cathode side may be as high as 120%, and
that on the anode side may be as low as 75%.
32. 1. As the angle of the anode decreases the
anode heel effect increases
2. The distance from the anode to the image
receptor greatly influence the apparent
magnitude of the anode heel effect.
3. This effect is less noticeable at large FFD
4. Larger the field size more prominent the heel
effect
5. Smaller the field size results in less
pronounced heel effect
33. Curved anode VS flat anode
• Curved anode in comparison to flat anode do not produce
objectionable heel effect and also anode curvature might seem
to offer a potential improvement in heat capacity
34. Applications of anode heel effect
• Anode heel effect is important during the
radiography of non uniform anatomical
structures
• The heel effect is important when one is imaging
anatomical structures that differ greatly in thickness
or mass density
• In general, positioning the cathode side of the x-ray
tube over the thicker part of the anatomy provides
more uniform radiation exposure of the image
35. Contd……
• For eg,
radiography of foot
radiography of lumbar spine
radiography of abdomen
• Also, it is important in context of the radiation
protection for the patients
• For eg,
head of the female patient is placed at the cathode
end of the x-ray tube to achieve a significant dose
reduction to the ovaries and hence lower effective
dose in lumber spine radiography
36.
37.
38. Anode heel effect in the
mammography
• Anode angulation = 6 degree
• Tube angle = 23 to 25 degree
• Focal spot = 0.1 to 0.3 mm
• As a result we get perpendicular beam towards
cathode where the chest wall is positioned that
cause less scattering of radiation and increases
resolution as well
39.
40. Off focus radiation
• X-ray tubes are designed so that projectile electrons
from the cathode interact with the target only at the
focal spot.
• However, some of the electrons bounce off the focal
spot and then land on other areas of the target,
causing x-rays to be produced from outside of the
focal spot). These x-rays are called off-focus
radiation
• The main source of off focus radiation is
scattered electrons at the target.
41.
42. Control of off focus radiation
• A diaphragm is placed between the tube and
the collimator to reduce off focus rays.
• Metal enclosure decreases off focus radiation
by attracting off- focus electrons to the
grounded metal wall of the x-ray tube
43. Summary
• Line focus principle is the angulation of the anode
to achive smaller effective focal spot on larger
actual focal spot for greater heat dissipation and
the improvement in the image quality.
• Anode heel effect is the decrease in the intensity
of radiation at anode side than in cathode side due
to the absorption and attenuation of the radiation
by the heel of the anode
• Off focal radiation is the radiation which is
produced by the bombardment if the electrons on
other areas of the target outside the focal track
45. refrences
• Christensen’s physics of diagnostic radiology
• Radiologic science for technologists by
Stewart Carlyle Bushong
• www.google.com
46. Questions
1. What is the variation in the beam intensity that
appears due to anode heel effect?
2. What is difference between apparent and actual
focal spot?
3. Describe the relationship between apparent and
actual focal spot and tube angle
4. Importance of anode heel effect with examples
5. Correlate the importance of angulation of anode
surface with line focus principle