medical physics powerpoint presentation

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Medical Physics Public Education Website: https://www.medicalradiationinfo.org/

Medical physics as a career.

PowerPoint Presentation (5.61MB) The AAPM Public Education Committee has created a PowerPoint presentation that all members can use to promote "what does it mean to be a medical physicist". This slide set is appropriate for talking with high school students to get them interested in the field of medical physics, for undergraduate science majors to entice them in to the field as graduate students and to others in the medical community to foster a better understanding of what a medical physicist is, does and the role they play in diagnosis and treatment of cancer and benign disease. For NON MEMBERS - Further Information

Introduction to Medical Imaging Modalities

A series of videos sponsored by the National Institute of Biomedical Imaging and Bioengineering that provide a basic introduction and overview of several diagnostic imaging modalities. View Video Series

Medical Physics Education for Middle/High School Students

The Institute of Physics's Medical Physics Group has produced a set of teaching materials which can be used to teach medical physics at GCSE/Standard level in schools. Much of the material is appropriate to use for A-level medical physics options. The Institute's Teaching Medical Physics resources, that include Positron Emission Tomography, Gamma Cameras, Electrocardiograms, X-ray Imaging, Ultrasound, Pulse Oximeters and Magnetic Resonance Imaging, consist of presentations, teachers' notes, student worksheets and videos from the Institute of Physics, Schools and Colleges Lecture 2011, "From X-rays to Anti-matter, The Science of Seeing Inside Your Body". The other files contain lessons as PowerPoint presentations and other material aimed at helping teachers to teach science with examples from medical physics. The presentations can be used as free-standing lessons at GCSE level (on the electromagnetic spectrum, radioactivity and ultrasound), or parts of the presentations may be used at A level or earlier, or for particular topics such as the Doppler effect, radiation safety or waves. The resources are free but you must register to gain access to the materials. View Teaching Materials

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Medical Physics

The Institute of Physics's Medical Physics Group has produced a set of teaching materials which can be used to teach medical physics at GCSE/Standard level in schools. Much of the material is appropriate to use for A-level medical physics options.

The Institute's Teaching Medical Physics resources, that include Positron Emission Tomography, Gamma Cameras, Electrocardiagrams, X-ray Imaging, Ultrasound, Pulse Oximeters and Magnetic Resonance Imaging, consist of presentations, teachers' notes, student worksheets and videos from the Institute of Physics, Schools and Colleges Lecture 2011, "From X-rays to Anti-matter, The Science of Seeing Inside Your Body".

The other files contain lessons as Powerpoint presentations and other material aimed at helping teachers to teach science with examples from medical physics. The presentations can be used as free-standing lessons at GCSE level (on the electromagnetic spectrum, radioactivity and ultrasound), or parts of the presentations may be used at A level or earlier, or for particular topics such as the Doppler effect, radiation safety or waves.

• Activity sheet
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• Teacher guidance
• Include Physical Resources

Pulse Oximeters

This resource from the Institute of Physics (IOP), describes how light can be used in pulse oximetry to measure pulse rate and oxygen levels in the body. The video, taken from an IOP Schools and Colleges lecture, describes how shining red and infra-red light through the body can be used to measure pulse rate and...

Ultrasound *suitable for home teaching*

This resource from the Institute of Physics, describes how ultrasound can be used to image the body. The video describes how ultrasound can be used to image a professional footballer's knee to investigate the cause of pain. The teachers' notes contain an introduction to ultra-sound imaging, lesson notes linked to...

Electrocardiagrams

This resource from the Institute of Physics, describes how electrocardiagrams (ECGs) record the activity of the heart through electrodes placed on a patient's skin. The teacher's notes contain an introduction to ECGs and lesson notes for the associated PowerPoint file. A mark scheme for the worksheet is also...

Gamma Cameras

This resource from the Institute of Physics (IOP), describes how cameras sensitive to gamma radiation can be used to image the body. The video, taken from an IOP Schools and Colleges lecture, briefly describes the history of the discovery of radioactivity and how the first particle accelerators could be used to...

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Did you like this resource, lists that tag this content, world radiography day , posted by tom lyons - stem enrichment lead.

PHYS 354: Medical Physics Principles: Presenting

• Biomedical Optics
• Biomedical Technology
• General Medicine + Biology
• Magnetic Resonance Imaging
• Nuclear Medicine
• Radiation Therapy
• Radiology + Medical Physics
• Ultrasound & Photoacoustics
• Medical Physics Resources
• Physics Citations
• Summarizing Research Articles & Annotated Bibliographies
• Sources + Literature Review
• Reference Management
• KU Library Resources

Giving a Presentation

Here are a few tools and suggestions to help prepare you for getting up and presenting in front of a class. Hopefully, you'll be inspired to improve upon the traditional PowerPoint slideshow and integrate technology into your presentations. 

Check out these articles for more advice on crafting an engaging and effective presentation:

• Designing Effective Virtual Presentations by KU Online
• What it Takes to Give a Great Presentation
• 1 0 Tips for Improving Your Public Speaking Skills
• Six Tips for Giving a Fabulous Academic Presentation
• 12 Reasons Your Presentation Sucks and How to Fix It
• 16 Useful Tips to Overcome Your Fear of Public Speaking

Sharing Your Presentation

Slideshare  allows you to share presentations online. Slides are uploaded to Slideshare, searchable, and able to be shared or embedded across the internet.

Speaker Deck is another option for sharing your presentations online. It is similar to the style of Slideshare, but is ad free. Also, when you embed slideshows, they will automatically resize to the size of the space in which they are being embedded.

Library Resources

PowerPoint , one piece of the Microsoft Office Suite, is perhaps the best known tool for creating presentations. While everyone has seen dry presentations consisting primarily of text on slides, PowerPoint can do much more than this, including offering embedded content such as images, videos, audio files and even dynamic content from the internet.

These tools will help you to do more with your PowerPoint slides.

• 21 PowerPoint Add-ins and Plugins 
• PowerPoint Twitter Tools These free tools allow users to interact with their audience via Twitter while presenting. You can poll the audience, take questions and feedback or auto-tweet your presentation all using these Twitter add-ons.

Prezi  allows users to create dynamic "zooming" presentations. If you have already created a PowerPoint presentation, it also offers an option to import your existing slides to Prezi. Presentations are created, stored and delivered online.

Prezi offers a large number of tutorials to help you with every step of the process on  their YouTube channel . The video below shows how to get started. You can also find examples of Prezis in  their gallery .

Emaze is an online presentation platform built on  HTML5  technology. Users can create, manage and share their presentations from any browser or mobile device. Emaze offers a variety of templates including formats using 3D animations and video backgrounds. Browse their gallery or view the sample presentation below:

Google Slides

Google Slides is to PowerPoint what Google Docs is to Word. It allows users with a free Google Drive account to create quick and easy presentations. While it doesn't have quite as many features as PowerPoint or others, it makes collaboration simple and works well for basic presentations. Google has a  great tutorial  to walk you through its features or you can watch the video below.

Thanks to Harvard Law School Library for inspiration in creating this LibGuide.

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• Last Updated: Mar 7, 2024 1:24 PM
• URL: https://libguides.kettering.edu/PHYS354

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• Nuclear Medicine Handbook slides

The IAEA has recently published the Nuclear Medicine Physics Handbook , which is intended for teachers, students and residents involved in medical physics programmes, and aspiring to serve as primary text for academic education and clinical training of Nuclear Medicine Medical Physicists in the IAEA Member States. The handbook provides a comprehensive overview of the knowledge required in physics, instrumentation and data processing for the practice of medical physics in modern nuclear medicine.

The book is comprised of 20 chapters and one appendix, beginning with a general introduction to the basic physics for nuclear medicine and progressing logically through a series of chapters addressing radiobiology, radiation safety, radionuclide production, non-imaging and imaging instrumentation (including gamma cameras, SPECT and PET scanners, and multimodality devices), image processing and reconstruction, radiopharmacy, quantitative nuclear medicine, internal dosimetry in clinical practice and radionuclide therapy. Each chapter concludes with a small number of references and suggested additional readings.

The technical editors and authors, selected for their experience and in recognition of their contributions to the field, were drawn from around the world and, thus, this book represents a truly international collaboration. The handbook was written to address an urgent need for a comprehensive, contemporary text on the physics of nuclear medicine and has been endorsed by several international and national organizations.

Additional training material, in the form of teaching slides, has been developed for each chapter of the handbook. They are designed, as an additional training tool to assist in the better presentation of the content of each chapter. Please, let us know if you discover any errors in the handbook or slides, or if you have suggestions as to the appropriateness of the content or its level. Please, respond in writing to [email protected] .

Dowload the Powerpoint version of the slides

Set of accompanying slides (pdf) :.

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Ultrasound (A-level Medical Physics)

Subject: Physics

Age range: 16+

Resource type: Other

Last updated

19 February 2021

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One of six PowerPoint presentations for the Medical Physics unit of A-level OCR Physics A, matched to the Oxford OCR A-Level Physics A textbook. This PPT covers the production and use of ultrasound.

Please note that the TES software that produces thumbnail images doesn’t always seem to handle background images in PPT slides very well. If the thumbnails look odd on your display, that is not how they really look!

See it in use: https://youtu.be/Dvqbopuajb0

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Medical Physics for OCR A-level Physics A

A collection of six PowerPoint presentations for the Medical Physics unit of A-level OCR Physics A, matched to the Oxford OCR A-Level Physics A textbook. Please note that the TES software that produces thumbnail images doesn't always seem to handle background images in PPT slides very well. If the thumbnails look odd on your display, that is not how they really look! See them in action: https://youtube.com/playlist?list=PLF4ZjVc-ocdprOCp-CzcSvpGxIk4BJ3fR

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Medical Physics

Jul 21, 2014

910 likes | 1.45k Views

Medical Physics. The Vision. Physics in Biology and Medicine By Paul Davidovits. Optics علم البصريات , which is the study of light, is one of the oldest branches of physics. It includes topics such as microscopes, telescopes, vision ,

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Presentation Transcript

Medical Physics The Vision Physics in Biology and Medicine By Paul Davidovits

Optics علم البصريات , which is the study of light, is • one of the oldest branches of physics. It includes • topics such as microscopes, telescopes, vision, • color, pigmentsمادة كيميائيه تغير لون الضوء المنعكس عليها ,illumination إضاءه , spectroscopy التحليل الطيفي , and • lasers, all of which have applications in the life • sciences. • In this chapter, we will discuss four of these • topics: vision, telescopes, microscopes, and optical • fibers.

1-Vision • Vision is our most important source of information • about the external world. • It has been estimated that about 70% of a • person’s sensory input is obtained through the eye. • The three components of vision are • 1-the stimulus, which is light • 2-the optical components of the eye, which image the light • 3-the nervous system, which processes تعالج و يحمض and interpretsو تفسر the visual images.

2- Nature of Light Experiments performed during the nineteenth century showed that light exhibits all the properties of wave motion. At the beginning of this century, however, it was shown that wave concepts alone do not explain completely the properties of light. In some cases, light and other electromagnetic radiation behave as if composed of small packets (quanta) of energy.

These packets of energy are called photons. For a given frequency fof the radiation, each photon has a fixed amount of energy E which is where h is Planck’s constant, equal to 6.63×10−27 erg-sec. we must be aware of both of these properties of light. The wave properties : explain all phenomena associated with the propagation of light through bulk matter في الاجسام, and the quantum nature of light must be invoked to understand the effect of light on the photoreceptors المستقبل الضوئي in the retina.

3-Structure of the Eye The eye is roughly a sphere,approximately 2.4 cm in diameter. All vertebrate eyes are similar in structurebut vary in size. Light enters the eye through the cornea, which is a transparent section in the outer cover of the eyeball. The light is focused by the lens system of the eye into an inverted image at the photosensitive retina, which covers the back surface of the eye.

Here the light produces nerve impulses that convey information to the brain. The focusing of the light into an image at the retina is produced by the curvedsurface of the cornea and by the crystalline lens inside the eye. The focusing power of the cornea is fixed. The focus of the crystalline lens, however, isalterableقابل للتغيير, allowing the eye to view objects over a wide range of distances.

The human eye.

In front of the lens is the iris, which controls the size of the pupil, or entrance aperture into the eye. Depending on the intensity of the light, the diameter of the aperture ranges from 2 to 8 mm. The cavity of the eye is filled with two types of fluid, both of which have a refractive index معامل انكسار about the same as water. The front of the eye, between the lens and the cornea, is filled with a watery fluid called the aqueous humor. The space between the lens and the retina is filled with the gelatinous vitreous humor.

4-Accommodation The focusing of the eye is controlled by the ciliary muscle, which can change the thickness and curvature of the lens. This process of focusing is called accommodation. When the ciliary muscle is relaxed, the crystalline lens is fairly flat, and the focusing power of the eye is at its minimum.

Under these conditions, a parallel beam of light is focused at the retina. Because light from distant objects is nearly parallel, the relaxed eye is focused to view distant objects. In this connection, “distant” is about 6m and beyond. The viewing of closer objects requires greater focusing power.

The light from nearby objects is divergentas it enters the eye; therefore, it must be focused more strongly to form an image at the retina. There is, however, a limit to the focusing power of the crystalline lens. With the maximum contraction انقباض of the ciliary muscle, a normal eye of a young adult can focus on objects about 15 cm from the eye. Closer objects appear blurred.

The minimum distance of sharp focus is called the near point of the eye The focusing range of the crystalline lens decreases with age. The near point for a 10-year-old child is about 7 cm, but by the age of 40 the near point shifts to about 22 cm. After that the deterioration التلف is rapid. At age 60, the near point is shifted to about 100 cm. This decrease in the accommodation of the eye with age is called presbyopia.

5-Eye and the Camera Although the designers of the photographic camera did not imitate the structure of the eye, many of the features in the two are remarkably similar. Both consist of a lens system that focuses a real inverted image onto a photosensitive surface. In the eye, as in the camera, the diameter of the light entrance is controlled by a diaphragm that is adjusted in accord with the available light intensity.

The eye and the camera.

In a camera, the image is focused by moving the lens with respect to the film. In the eye, the distance between the retina and the lens is fixed; the image is focused by changing the thickness of the lens. Even the photosensitive surfaces are somewhat similar. Both photographic film and the retina consist of discrete light-sensitive units, microscopic in size, which undergo chemical changes when they are illuminated.

In fact, under special circumstances, the retina can be “developed,” like film, to show the image that was projected on it. This was first demonstrated in the 1870s by the German physiologist W. Kuhne. He exposed the eye of a living rabbit to light coming through a barred مخططwindow. After 3 minutes of exposure to light, the rabbit was killed and its retina was immersed in an alum solution which fixed the retinal reaction. The barred window was clearly visible on the retina. A few years later, Kuhne fixed the retina from the head of a guillotined criminalمجرم اثناء اعدامه. He observed an image, but he could not interpret it in terms of anything that the man had seen before he was beheaded. The analogy between the eye and the camera, however, is not complete. As we will describe later, the eye goes far beyond the camera in processing the images that are projected on the retina.

5.1 Aperture and Depth of Field The iris is the optical aperture of the eye, and its size varies in accordance with the available light. If there is adequate light ضوء مناسب, the quality of the image is best with the smallest possible aperture. This is true for both the eye and the camera. There are two main reasons for the improved image with reduced aperture.

1-Imperfections in lenses tend to be most pronounced around the edges. A smallaperture restricts the light path to the center of the lens and eliminates the distortions and aberrationsتشوه و انحراف produced by the periphery. 2- A smaller aperture also improves the image quality of objects that are not located at the point on which the eye or the camera is focused.

An image is in sharp focus at the retina (or film) only for objects at a specific distance from the lens system. Images of objects not at this specific plane are blurred at the retina as in the next Fig.; in other words, a point that is not in exact focus appears as a disk on the retina.

Size of image disk: (a) with large aperture, (b) with small aperture.

The amount of blurring depends on the size of the aperture. As shown in Fig., a small aperture reduces the diameter of the blurred spot and allows the formation of a relatively clear image from objects that are not on the plane to which the eye is focused. The range of object distances over which a good image is formed for a given setting of the focus is called the depth of field.

Clearly a small aperture increases the depth of field. It can be shown that: The depth of field is inversely proportional to the diameter of the aperture.

6- Lens System of the Eye The focusing of the light into a real inverted image at the retina is produced by refractionالانكسار at the cornea and at the crystalline lens. Focusing by the cornea and the crystalline lens

Parameters for the Eye

The largest part of the focusing التمركز, about two thirds, occurs at the cornea. The power of the crystalline lens is small because its index of refraction is only slightly greater than that of the surrounding fluid.

Using the data in the table and calculate the focusing power of the cornea and of the crystalline lens and using the equation Focusing power = 1/f Where f is the focal lengths, it is shown that the refractive power of the cornea is 42 diopters, and the refractive power of the crystalline lens is variable between about 19 and 24 diopters. (diopter= 1/meter)

The refractive power of the cornea is greatly • reduced when it is in contact with water. • Because the crystalline lens in the human eye • cannot compensate for the diminished power of the • cornea, the human eye under water is not able to form a • clear image at the retina and vision is blurred. • In fish eyes, which have evolved for seeing under water, • the lens is intended to do most of the focusing.

7-Reduced Eye To trace accurately the path of a light ray through the eye, we must calculate the refraction at four surfaces (two at the cornea and two at the lens). It is possible to simplify this procedure with a model called the reduced eye, shown in Fig. The reduced eye.

Here all the refraction is assumed to occur at the front surface of the cornea, which is constructed to have a diameter of 5 mm. The eye is assumed to be homogeneous, with an index of refraction of 1.333 (the same as water). The retina is located 2 cm behind the cornea. The nodal point n is the center of corneal curvature located 5mm behind the cornea.

The triangles AnB and anb are similar; therefore, the relation of object to image size is given by Object size, Image size, Distance. (nodal point n is the center of corneal curvature located 5mm behind the cornea)

Determination of the image size on the retina. Consider as an example the image of a person 180 cm tall standing 2m from the eye. The height of the full image at the retina is The size of the face in the image is about 1.8 mm, and the nose is about 0.4 mm.

8- Retina The retina consists of photoreceptor cells in contact with a complex network of neurons and nerve fibers which are connected to the brain via the optic nerve. Light absorbed by the photoreceptors produces nerve impulses that travel along the neural networkالشبكة العصبية and then through the optic nerveالعصب البصري into the brain.

The retina.

The photoreceptors are located behind the neural network, so the light must pass through this cell layer before it reaches the photoreceptors. • There are two types of photoreceptor cellsin the retina: cones and rods. • The cones are responsible for sharp color vision in • daylight. • The rods provide vision in dim light.

Near the center of the retina is a small depression about 0.3mm in diameter which is called the fovea. It consists entirely of cones packed closely together. Each cone is about 0.002mm (2μm) in diameter. Most detailed vision is obtained on the part of the image that is projected on the fovea. When the eye scans a scene مشهد, it projects the region of greatest interest onto the fovea.

The region around the fovea contains both cones and rods. The structure of the retina becomes more coarse جافaway from the fovea. The proportion of cones decreases until, near the edge, the retina is composed entirely of rods. In the fovea, each cone has its own path to the optic nerve. This allows the perceptionملاحظة of details in the image projected on the fovea.

9-Defects in Vision There are three common defects in vision associated with the focusing system of the eye: myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The first two of these defects are best explained by examining the imaging of parallel light by the eye.

The relaxed normal eye focuses parallel light onto the retina (Fig. 15.10). The normal eye.

In the myopic eye the lens system focuses the parallel light in front of the retina (Fig. 15.11a). (a) Myopia. (b) Its correction.

This misfocusing is usually caused by an elongated eyeball or an excessive curvature of the cornea. In hyperopia the problem is reversed (see Fig. 15.12a) (a) Hyperopia. (b) Its correction.

Parallel light is focused behind the retina. The problem here is caused by an eyeball that is shorter than normal or by the inadequate focusing power of the eye. The hyperopic eye can accommodate objects at infinity, but its near point is farther away than is normal. Hyperopia is, thus, similar to presbyopia. These two defects can be summarized as follows: The myopic eye converges light too much, and the hyperopic eye not enough.

Astigmatism:is a defect caused by a nonspherical cornea. An oval-shaped cornea, for example, is more sharply curved along one plane than another; therefore, it cannot form simultaneously sharp images of two perpendicular lines. One of the lines is always out of focus, resulting in distorted vision. Cylindrical lens for astigmatism.

All three of these defects can be corrected by lenses placed in front of the eye. Myopia: requires a diverging lens to compensate for the excess refraction in the eye. Hyperopia: is corrected by a converging lens, which adds to thefocusing power of the eye. The uneven corneal curvature in astigmatism: is compensated for by a cylindrical lens, which focuses light along one axis but not along the other.

10-Lens for Myopia Let us assume that the farthest object a certain myopic eye can properly focus is 2m from the eye. This is called the far point of the eye. Light from objects farther away than this is focused in front of the retina (Fig. 15.11a). Here the purpose of the corrective lens is to make parallel light appear to come from the far point of the eye (in this case, 2m).

With such a corrective lens, the eye is able to form images of objects all the way to infinity. The focal length of the lens is obtained by using Eq. C.6, which is Here p is infinity, as this is the effective distance for sources of parallel light. The desired location q for the virtual image is −200 cm. The focal length of the diverging lens (see Eq. C.4) is, therefore,

11-Lens for Presbyopia and Hyperopia In these disorders, the eye cannot focus properly on close objects. The near point is too far from the eye. The purpose of the lens is to make light from close objects appear to come from the near point of the unaided eye. Let us assume that a given hyperopic eye has a near point at 150 cm. The desired lens is to allow the eye to view objects at 25 cm.

The focal length of the lens is again obtained from Eq. C.6, Here p is the object distance at 25 cm and q is −150 cm, which is the distance of the virtual image at the near point. The focal length f for the converging lens is given by

12-Extension of Vision The range of vision of the eye is limited. Details on distant objects cannot be seen because their images on the retina are too small. The retinal image of a 20m-high tree at a distance of 500m is only 0.6mm high. The leaves on this tree cannot be resolved by the unaided لم تتم مساعدته eye. Observation of small objects is limited by the accommodation power of the eye.

We have already shown that, because the average eye cannot focus light from objects closer than about 20 cm, its resolution is limited to approximately 100μm. Over the past 300 years, two types of optical instruments have been developed to extend the range of vision: the telescope and the microscope.

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• Preferences

Medical Physics - PowerPoint PPT Presentation

Medical Physics

Part 8: occupational exposure part no 3, lesson no 1 biology iaea training material: radiation protection in radiotherapy * part 1. biological effects of ionizing ... – powerpoint ppt presentation.

• 1895 X Rays discovered by Roentgen
• 1896 First skin burns reported
• 1896 First use of X Rays in the treatment of cancer
• 1896 Becquerel Discovery of radioactivity
• 1897 First cases of skin damage reported
• 1902 First report of X Ray induced cancer
• 1911 First report of leukaemia in humans and lung cancer from occupational exposure
• 1911 94 cases of tumour reported in Germany (50 being radiologists)
• PREVENTION of deterministic effect.
• LIMITING the probability of stochastic effect
• RS Probability of a cell, tissue or organ of suffering an effect per unit of dose.
• It is generally assumed that even very small doses of ionizing radiation can potentially be harmful .
• Therefore, persons must be protected from ionizing radiation at all dose levels.
• Members of his/her family.
• General public.
• Persons are medically exposed as part of their diagnostic or treatment
• According to IAEA, ICRP and BSS, two basic principles of radiation protection are to be complied with
• justification and optimization
• Justification
• Optimization
• Dose Limitations
• (dose directly proportional to length of exposure).
• (b/w source and patient).
• (Intensity and StP distance).
• No use of ionizing radiation is justified if there is no benefit.
• All applications must be justified.
• This implies All, even the smallest exposures are potentially harmful and the risk must be offset by a benefit.
• The decision to adopt or continue any human activity involves a review of benefits and disadvantages of the possible options
• E.g. choosing between the use of X Rays or ultrasound
• Most of the assessments needed for the justification of a practice are made on the basis of experience, professional judgement, and common sense.
• Need to evaluate the benefits of radiation - an easy task in the case of nuclear medicine.
• Radiation is the diagnostic and therapeutic agent.
• Assessment of the risks requires the knowledge of the dose received by persons.
• When radiation is to be used then the exposure should be optimized to minimize any possibility of detriment.
• Optimization is doing the best you can under the prevailing conditions.
• Need to be familiar with techniques and options to optimize the application of ionizing radiation - this is really the main objective of the present course.
• Reducing the patient dose may reduce the quantity as well as the quality of the information provided by the examination or may require important extra resources.
• Means that doses should be As Low As Reasonably Achievable ALARA, economic and social factors being taken into account compatible with achieving the required objective.
• Image quality depends on
• Administered activity
• Technical factors - equipment used - acquisition protocol - image processing evaluation - noise - spatial resolution
• Patient factors - size
• - disease - movement
• The use of doses limits is NOT APPLICABLE
• Dose constraints and guidance (or reference) levels ARE RECOMMENDED
• Medical Exposure (principally the exposure of persons as part of their diagnostic or treatment)
• Occupational Exposure (exposure incurred at work, and practically as a result of work)
• Public Exposure (including all other exposures)
• Medical Exposure
• Exposure of persons as part of their diagnostic or treatment.
• Exposures incurred by volunteers as part of a program of biomedical research.
• (a) No patient to be administered a diagnostic or therapeutic medical exposure unless the exposure is prescribed by a medical practitioner
• (d) For therapeutic uses of radiation, the calibration, dosimetry and quality assurance requirements of the Standards be conducted by or under the supervision of a qualified expert in radiotherapy physics.
• effective dose of 1 mSv/year
• equivalent dose to lens of the eye 15 mSv/yr
• equivalent dose to skin of 50 mSv/year.
• Dose Limits
• effective dose of 5mSv per year averaged over five consecutive years
• equivalent dose to lens of eye of 150mSv in a year
• equivalent dose to extremities or skin of 500mSv in a year.
• For apprentices (16-18 years of age)
• effective dose of 6mSv in a year
• Female workers should notify pregnancy.
• Working conditions shall be adapted to ensure that the embryo and fetus are afforded the same broad level of protection as for members of the public.
• Mr. Sharp, I am given to understand that 2 bone scans and a cardiac study done on me have given me 22 mSv whereas 20 mSv is the safe dose. I want to file legal suit against the doctor. What do you feel??

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Seismologists suspect earthquake on San Andreas Fault is imminent despite odd attenuation parameters

by Bob Yirka , Phys.org

A trio of seismologists affiliated with Istituto Nazionale di Geofisica e Vulcanologia, the Berkeley Seismological Laboratory, University of California, Berkeley reports that a part of the San Andreas Fault, at Parkfield, is not producing signals that would suggest an earthquake is going to happen any time soon, but they assert there are factors that suggest otherwise.

The paper, authored by Luca Malagnini, Robert Nadeau and Tom Parsons, is published in the journal Frontiers in Earth Science

The part of the San Andreas Fault located near Parkfield, California, offers scientists who study earthquakes a unique opportunity: Just north of Parkfield, two major plates creep against one another at a constant rate. South of Parkfield, on the other hand, the fault is locked. Because of this, earthquakes happen there in a pattern—roughly every 22 years.

That allows researchers to gather seismic data before, during and after a quake. Such quakes are almost always the same magnitude as well, approximately 6 or slightly higher. The last quake to happen at the site occurred in 2004, which suggests a quake should be coming in the next couple of years. But there is a problem—seismic activity related to the fault does not indicate any signs of an earthquake. Usually, they note, low-frequency waves attenuate prior to a quake, while high-frequency waves increase. But there is no sign of either right now.

The research team notes that the last earthquake to occur in the area was approximately 14 years late. But that was because other earthquakes occurred in close enough proximity to take the pressure off Parkfield—that is not the case this time around. Still, the researchers believe a quake is going to happen soon because of other factors.

These include pressure in nearby parts of the fault that could lead to an earthquake , but with a somewhat displaced epicenter.

The researchers do not have high confidence in their readings; thus, they are not going to be making any formal predictions. Instead, they suggest, as is always the case with earthquakes, everyone will just have to wait and see what happens. In this case, though, waiting is not such a problem—hardly anyone lives in the area.

Journal information: Frontiers in Earth Science

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