The document discusses the properties and production of x-rays. Some key points:
- Wilhelm Roentgen discovered x-rays in 1895 and was awarded the first Nobel Prize in Physics for this work.
- X-rays are a type of electromagnetic radiation produced when electrons are accelerated and decelerated. They can behave as waves or particles.
- In an x-ray tube, a high voltage is used to accelerate electrons towards a metal target, where x-rays are produced via braking radiation or characteristic radiation.
- X-rays can be absorbed or scattered in matter. Their interaction depends on tissue electron density and thickness and the x-ray energy. These interactions are useful in medical imaging.
Recent advancements in modern x ray tubeSantosh Ojha
All the advancements in X-ray tubes till date are done to increase the Tube heat storage capacity thus increasing the lifetime of x -ray tubes. This slide explains about these recent advancements in x-ray tubes.
Interactions of X-ray & matter & Attenuation - Dr. Sayak DattaSayakDatta
Slideshow on Radio-physics covering different interactions between X-ray and matter along with Attenuation. It includes Photo-electric effect, Compton scatter, Coherent scatter, Attenuation of Monochromatic & Polychromatic radiation, Diagnostic Xray applications, Scatter radiations.
Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination.
Ionizing radiation is widely used in industry and medicine, and can present a significant health hazard by causing microscopic damage to living tissue. There are two main categories of ionizing radiation health effects. At high exposures, it can cause "tissue" effects, also called "deterministic" effects due to the certainty of them happening, conventionally indicated by the unit gray and resulting in acute radiation syndrome. For low level exposures there can be statistically elevated risks of radiation-induced cancer, called "stochastic effects" due to the uncertainty of them happening, conventionally indicated by the unit sievert.
Fundamental to radiation protection is the avoidance or reduction of dose using the simple protective measures of time, distance and shielding. The duration of exposure should be limited to that necessary, the distance from the source of radiation should be maxi mised, and the source shielded wherever possible. To measure personal dose uptake in occupational or emergency exposure, for external radiation personal dosimeters are used, and for internal dose to due to ingestion of radioactive contamination, bioassay techniques are applied.
Recent advancements in modern x ray tubeSantosh Ojha
All the advancements in X-ray tubes till date are done to increase the Tube heat storage capacity thus increasing the lifetime of x -ray tubes. This slide explains about these recent advancements in x-ray tubes.
Interactions of X-ray & matter & Attenuation - Dr. Sayak DattaSayakDatta
Slideshow on Radio-physics covering different interactions between X-ray and matter along with Attenuation. It includes Photo-electric effect, Compton scatter, Coherent scatter, Attenuation of Monochromatic & Polychromatic radiation, Diagnostic Xray applications, Scatter radiations.
Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination.
Ionizing radiation is widely used in industry and medicine, and can present a significant health hazard by causing microscopic damage to living tissue. There are two main categories of ionizing radiation health effects. At high exposures, it can cause "tissue" effects, also called "deterministic" effects due to the certainty of them happening, conventionally indicated by the unit gray and resulting in acute radiation syndrome. For low level exposures there can be statistically elevated risks of radiation-induced cancer, called "stochastic effects" due to the uncertainty of them happening, conventionally indicated by the unit sievert.
Fundamental to radiation protection is the avoidance or reduction of dose using the simple protective measures of time, distance and shielding. The duration of exposure should be limited to that necessary, the distance from the source of radiation should be maxi mised, and the source shielded wherever possible. To measure personal dose uptake in occupational or emergency exposure, for external radiation personal dosimeters are used, and for internal dose to due to ingestion of radioactive contamination, bioassay techniques are applied.
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
PRESENTATION IS COMPACT AND INFORMATIVE. HAS FLOWCHARTS AND DIAGRAMS. REFERENCE IS FROM LATEST ARTICLES AND STANDARD TEXTBOOKS. SERVES A GREAT DEAL TO BRUSH UP THE THEORETICAL KNOWLEDGE .
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
2. Wilhelm Conrad Roentgen discovered x rays on
November 8, 1895
Properties of x rays - December 28, 1895
Was awarded the first Nobel Prize for Physics in
1901
International day of Radiology – November 8
3. X rays belong to a group of radiations called electromagnetic radiation,
which is the transport of energy through space as a combination of electric and
magnetic fields.
Radio waves, radiant heat, visible light and gamma radiation
Electromagnetic radiation is produced by a charged particle being accelerated
(type of energy).
6. Nucleus of an atom – Protons(Z) + neutrons
Electrons orbit in specific shells (K, L, M, N, etc.) around the nucleus
Orbiting electrons – Properties of X rays and its interaction with matter
7. Ionizing radiation – Higher energy; emits electrons or other
particles from atom when they collide.
Eg. Alpha, gamma and x rays
Non ionizing radiation – Excites electrons from a lower level to a
higher level
Eg. UV, visible, infrared, microwave, radio waves
8. Wave concept
Electromagnetic radiation is propagated through space in the form of waves.
atom absorbs energy The absorbed energy causes one or more electrons to
change their location within the atom.
When the electron returns to its original position, an electromagnetic wave is
produced.
Depending on the kind of atom and the amount of energy, this electromagnetic
radiation can take the form of heat, light, ultraviolet, or other electromagnetic
waves.
9. Electromagnetic waves do not require a medium; they can be propagated
through a vacuum.
Distance b/w two successive crests - wavelength of the wave (λ).
Number of waves passing a particular point in a unit of time - frequency (ν).
Velocity of the wave, V = λ x ν.
10. Electromagnetic radiation travels at the same velocity in a vacuum
(3 x 108 meters per second)
Frequency inversely proportional to wavelength.
Electromagnetic radiation differs commonly in wavelength.
Wavelength of diagnostic x rays is extremely short and expressed in
angstrom units (Å) or nanometers.
11. Particle concept
Short electromagnetic waves (X rays) may react with matter as if they were
particles, which are usually discrete bundles of energy (quantum/ photon).
Describes the interactions between radiation and matter.
energy of quantum or photon ∝ frequency of radiation.
E = hν, where E = photon energy, h = Planck's constant and v = frequency
12.
13. X rays are produced by energy conversion when a fast moving stream of electrons is
suddenly decelerated in the target anode of an x ray tube.
X ray tube - Pyrex glass that encloses vacuum containing two electrodes (diode tube).
Electrons produced at cathode (negative electrode or filament) can be accelerated by a
high potential difference towards anode (positive or target electrode).
Electrons produced by a heated tungsten filament and accelerated across the tube to hit
the tungsten target, where x rays are produced.
14.
15. Two sources of electrical energy are required –
Filament heating voltage (10V) and current (10A)
Accelerating voltage (30-150kv) between anode and cathode – drives the current
of electrons flowing between anode and cathode (tube current)
Small increase in temperature produces large increase in tube current.
16. Fast moving electrons are suddenly stopped by impact on metal target
Electric charge of electron does not change the increasing voltage across the x ray tube
increase the kinetic energy of electron (E = ev)
High speed electrons lose energy at target by 2 processes –
Reaction of electrons with nucleus of tungsten atoms
Collision between high speed electrons and electrons in the shell of target tungsten
atom
17. Bremsstrahlung radiation
When an electron pass near the nucleus of a tungsten atom, the positive charge of
the nucleus acts on negative charge of electron.
The electron is thus deflected from its original position.
Electron may lose energy and slows down when its direction changes.
The kinetic energy lost by electron is directly emitted in the form of photon
radiation.
18. The electron only gives up part of its energy in
the form of radiation - braking radiation.
Braking phenomenon (wide distribution in
the energy of radiation) -
Electron undergoes many reactions before
coming to rest
Electron beam that strikes the target have
widely different energy.
19. Wavelength of the radiation produced depends on energy of the electron
(keV) and the potential difference (kVp) .
Deceleration of the electrons in the electric field of a nucleus depends on
how close the electron passes to the nucleus,
the energy of the electron and
the charge of the nucleus.
20. Characteristic radiation
The electrons bombarding the target ejects
electrons from the inner orbit of the target
atoms.
Removal of an electron from the tungsten atom
causes the atom to have an excess positive
charge → a positive ion.
21. In the process of returning to its normal state, the ionized atom of
tungsten may get rid of excess energy in two ways:
An additional electron (Auger electron) may be expelled by the atom and
carry excess energy [there is no x ray production in this way].
The atom emits radiation that has a wavelength within the range of
diagnostic x rays [characteristic x rays.
22. Properties of X rays Highly penetrating, invisible rays.
Liberate minute amounts of heat on passing through matter.
Behave both as waves and as particles.
Are not deflected by electric or magnetic fields. (electrically neutral).
Poly energetic, having wide spread of energies and wavelengths,
useful energy range 25 to 120 kVp.
23. Travels ordinarily in straight lines with same speed as light. (3x108 m/sec).
Cause fluorescence of certain crystals, making possible use in
fluoroscopy and
radiographic intensifying screens.
Produce biological and chemical changes by ionization and excitation in
substances through which they pass.
Cannot be focused by a lens.
Produce secondary and scattered radiation.
Ionize gases indirectly by ability to remove orbital electrons from atom.
24.
25. X-ray photons may interact either with the
1. orbital electrons or with the
2. nucleus of the atom
In diagnostic energy range, the interactions are always with orbital electrons.
Interactions depend on the atomic makeup of the tissue and not its molecular
structure. E.g. oxygen atoms will stop the same number of x-ray photons
regardless of their physical state.
26. X ray photons may be either absored / scatter.
If absorbed completely removed from the x ray beam cease to exist.
If scattered deflected into a random course no longer carries information
cannot portray an image (blackness) as NOISE / FILM FOG.
27. ATTENUATION – A reduction in the intensity (energy) of the beam
ABSORPTION – The transfer of energy from the beam to the irradiated
material.
SCATTER – Radiation in a direction other than the primary beam, with or
without a loss of energy
28. Radiation interaction depends on :
Tissue electron density
Tissue thickness
Energy of the x ray (kVp).
The various structures of the body attenuate by differing amounts.
30. Coherent scattering
When radiation undergoes a change in direction without a change in the
wavelength.
Occurs when low energy radiation encounters the electron of an atom and sets
them into vibration at the frequency of radiation.
Also termed as UNMODIFIED SCATERRING or CLASSICAL SCATTERING.
32. Two types –
Thompson scattering – single electron is involved.
Rayleigh scattering - cooperative interaction with all the
electrons of an atom.
33. Increases with low atomic number materials and lower photon energies.
Less than 5% of radiation undergoes coherent scattering.
Does not play a major role in diagnostic x rays.
This is the only type of interaction that does not cause ionization as there is
no energy transferred.
34. Photoelectric Effect The incident photon collides with the K shell electron Gives up its energy to the
electron to overcome the binding energy flies into the space as photoelectron
(negative ion)
The vacant spot in the K shell is filled by an electron from the adjacent L or M shell
electrons → x ray photon is released (characteristic radiation).
Atom deficient of one electron even if free electron from another atom fills the void→
end result is the same, a positive ion.
35.
36. Probability of Occurrence
Incident photon must have sufficient energy to overcome binding energy of the electron.
Likely to occur when the photon energy and electron binding energy are nearly the same;
photoelectric effect is inversely proportional to energy.
Tightly bound electrons are more likely to be involved in a photoelectric reaction; electrons are
more tightly bound in element with high atomic number.
37. Applications to diagnostic radiology
Advantages :
Produces good radiographic images
Does not produce scatter radiation
Enhances the natural soft tissue contrast
Film quality is good
Magnifies the difference in tissues composed of different elements
such as bone and soft tissue.
Disadvantages: Patient receives more radiation.
38. Compton scattering
An incident photon with relatively high energy strikes a free outer shell
electron ejects from its orbit travels a new direction as scatter radiation
Positive atom and negative electron “recoil” electron.
Energy of incident photon goes to recoil electron (as kinetic energy) and retained in
the deflected photon.
The amount of energy the photon retains depends on the initial energy and the angle of
deflection off the recoil electron.
Photons also have a momentum, and the higher the energy of the photon, the difficult
they are to deflect.
39. Probability of occurrence :
Depends on the total number and density of the electrons.
Higher the photon energy it is more likely to pass through the body than a low energy
photon
For elements with low atomic number, all the electrons can be considered free, even k
shell.
40. Pair production The photon interacts with the nucleus in such a manner that its energy is converted to
matter namely an electron and positron.
Both have the same mass and resting mass energy of 0.51 MeV.
Not encountered in diagnostic procedures as it involved photons with
energies in excess of 1.02 MeV.
41. Photodisintegration
Part of the nucleus of a atom is ejected by high energy photon.
The ejected particle may be a neutron, proton, alpha particle or a cluster of particles.
Incident photon must have sufficient energy to overcome nuclear binding energies of
7 – 15 MeV which is also far beyond diagnostic radiology and hence insignificant.
42. Only two interactions are important in diagnostic radiology, the
photoelectric effect and Compton scattering.
Coherent is numerically unimportant.
Pair production and photodisintegration = higher energies
The photoelectric effect is low energy interaction with high atomic number
absorbers produces high contrast.
Compton most common and is responsible for almost all scatter radiation
Summary