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DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE X-ray imaging teacher notes CRT04105 · Radiographic Imaging Sciences START READING NOTES Study X-ray imaging teacher notes using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. X-ray imaging teacher notes Copyright Institute of Physics 2012 Page 1 Teaching Medical Physics X-ray imaging Curriculum links Electromagnetic spectrum Background radiation Introduction X-ray imaging utilises the ability of high frequency electromagnetic waves to pass through soft parts of the human body largely unimpeded. For medical applications, X-rays are usually generated in vacuum tubes by bombarding a metal target with high-speed electrons and images produced by passing the resulting radiation through the patient’s body on to a photographic plate or digital recorder to produce a radiograph, or by rotating both source and detector around the patient’s body to produce a “slice” image by computerised tomography (CT). Although CT scans expose the patient to higher doses of ionising radiation the slice images produced make it possible to see the structures of the body in 3D. Lesson notes Radiography In X-ray radiography images are produced by casting an Xray shadow onto a photographic film or digital detector: Like gamma rays, X-rays can travel through soft tissues in body with little attenuation and are only “stopped” by high density tissues such as bone. Radiograph: Fully exposed areas of film/detector appear black. Dense objects block more X-rays and so appear white. Soft tissues like fat and muscle result in intermediate exposure and so appear grey. X-rays In the high- frequency/short-wavelength part of the electromagnetic spectrum the distinction between X-rays and gamma-rays is made by the origin of the waves: X-rays are emitted (by definition) by electrons outside the nucleus, while gamma rays are emitted by the nucleus. For most medical application X-rays are produced using evacuated tubes in which the electrons are accelerated up to high speed using large voltages. The X-rays are produced when the electrons hits a metal target.Copyright Institute of Physics 2012 Page 2 Teaching Medical Physics X-ray imaging Computerised tomography (CT) X-ray source and detector rotated around body as patient moves through scanner The data collected can be processed using a computer to produce a slice or 3D image. Compared to radiography, CT imaging better for: imaging of soft tissues differentiating between overlying structures in the body. PLAY: Scan of person moving through scanner (head to legs). Lungs and other major organs can be seen. X-ray dose CT scans require exposing the patient to higher dose of ionising radiation than radiographs which increases patient risk of cancer. Consequently, the additional risk associated with a CT scan must be weighed up against benefits of enhanced diagnostic capabilities (e.g. the ability to manipulate the data to produce 3D simulations) Exposure is measured in milliSievert (mSv) and is often expressed in equivalent background-radiation exposure time. Over a lifetime, medical X-rays contribute approximately 20 % of background level for the average person in UK. Chapter 3: launch chapter 3 of schools lecture 2011 on X-rays. Chapter 5: launch chapter 5 of schools lecture 2011 on CT scanning.Copyright Institute of Physics 2012 Page 3 Teaching Medical Physics X-ray imaging Worksheet Mark scheme 1. black; white Any one from: Images can be produced and checked immediately; OR There is no need for a developing film and disposing of expensive chemicals; OR Image can be manipulated to get the clearest possible picture; OR Image can be stored easily. 2. X-rays can pass through (soft tissues in) the body/have different frequency (high-speed) electrons (hit) metal target ultraviolet/UV [accept gamma-rays] 3. (X-rays cause) ionisation/changes in cells/damage DNA/ cancer. (CT scans) better at mapping soft tissues/ differentiating between overlying structures in the body/making 3D images Radon gas/ground/food/drink/cosmic rays Calculation of daily or annual background count rate: 0.0057 (mSv/day) or 2.1 (mSv/year) Answer: 246 days/0.67 years Total 10 marks ← PREVIOUS TOPICVIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Radiographic Imaging Sciences CRT04105 · Radiographic Imaging Sciences START READING NOTES Study Radiographic Imaging Sciences using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. Contents of This Topic Image formation and characteristics FILM CONSTRUCTION Base: A polyester material that provides support.- Radiographic Imaging Sciences When x-rays gamma rays, or light strike the grains Exposure to X-rays Interaction with Silver Halide Crystals Sensitivity Speck and Electron Capture Formation of Metallic Silver Invisible Until Developed Film storage and handling • Skin gets dry and brittle in low humidity and cold; so does film. Keeping your raw stock and exposed film safe Exposed Unprocessed: Use of envelope-packed films avoids many of these problems until the envelope is opened for processing. RADIOGRAPHIC IMAGING SCIENCES Image formation and characteristics Film construction Types of Film Latent image formation The duplication film process Film storage and handling Film identification X-ray Cassettes FILM CONSTRUCTION X-ray films for general radiography consist of an emulsion-gelatin containing radiation sensitive silver halide crystals, such as silver bromide or silver chloride, and a flexible, transparent, blue-tinted base. The emulsion is different from those used in other types of photography films to account for the distinct characteristics of gamma rays and x-rays but X-ray films are sensitive to light. Usually, the emulsion is coated on both sides of the base in layers about 0.0005 inch thick Duplitized film Single sided – film Base: A polyester material that provides support.- Adhesive Layer/Subbing layer : Binds the emulsion to the base.- Emulsion Layer: Contains silver halide crystals suspended in gelatin; this is where the image is formed.- Protective Layer: A thin coating to protect the emulsion from physical damage Radiographic Imaging Sciences Putting emulsion on both sides of the base doubles the amount of radiation-sensitive silver halide, and thus increases the film speed .The emulsion layers are thin enough so developing, fixing, and drying can be accomplished in a reasonable time. A few of the films used for radiography only have emulsion on one side which produces the greatest detail in the image. When x-rays gamma rays, or light strike the grains of the sensitive silver halide in the emulsion, some of the Br- ions are liberated and captured by the Ag+ ions. This change is of such a small nature that it cannot be detected by ordinary physical methods and is called a "latent (hidden) image Radiographic Imaging Sciences " However, the exposed grains are now more sensitive to the reduction process when exposed to a chemical solution (developer), and the reaction results in the formation of black, metallic silver. It is this silver, suspended in the gelatin on both sides of the base, that creates an image. Exposure to X-rays When the X-ray beam passes through the patient, it reaches the intensifying screen.- The screen converts X-rays into visible light (or sometimes direct X-rays hit the film in non-screen systems). Interaction with Silver Halide Crystals Interaction with Silver Halide Crystals:- The light (or X-rays) interacts with silver halide crystals (mainly silver bromide) in the emulsion layer of the film.- The energy from this interaction excites electrons within the crystals Sensitivity Speck and Electron Capture The free electron migrates to a sensitivity speck (a defect or impurity in the crystal) The speck becomes negatively charged and attracts positive silver ions (Ag⁺) Formation of Metallic Silver The silver ions gain electrons and are reduced to metallic silver (Ag).- This forms a small cluster of metallic silver atoms at the sensitivity speck — this is the latent image center. Invisible Until Developed These tiny metallic silver clusters are not yet visible.- During chemical processing, they are amplified to form a visible (manifest) image Film storage and handling Film seems to be derived from an old word for skin. Skin and film can be mistreated in similar ways: Skin can be scratched; so can film. Skin can be blistered by chemicals or heat; so can film. Skin can be damaged by prolonged exposure to the sun; so can film. • Skin gets dry and brittle in low humidity and cold; so does film. Skin is susceptible to fungus in excessive heat and relative humidity; so is film. Skin can be burned; so can film. Keeping your raw stock and exposed film safe Unprocessed film must be kept cool to preserve quality, ideally at 55°F / 13°C Keep film cool until just before shooting For storage of film for longer than 6 months, store at 0°F / -18°C Allow frozen film to warm up gradually before opening can, to avoid condensation Avoid prolonged exposure of film cans or camera magazines to sunlight Avoid storing film in hot vehicles Exposed Unprocessed: Process film promptly after exposure Avoid “Latent Image Regression” Keep film cool after exposure If processing is delayed, put film in refrigerator Allow frozen film to warm up gradually before opening can for processing Film storage and handling X-ray film should always be handled carefully to avoid physical strains, such as pressure, creasing, buckling, friction, etc Marks resulting from contact with fingers that are moist or contaminated with processing chemicals, as well as crimp marks, are avoided if large films are always grasped by the edges and allowed to hang free Use of envelope-packed films avoids many of these problems until the envelope is opened for processing. Another important precaution is to avoid drawing film rapidly from cartons, exposure holders, or cassettes. Such care will help to eliminate circular or treelike black markings in the radiograph that sometimes result due to static electric discharges. Film fog ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Radiographic Imaging Science CRT04105 · Radiographic Imaging Sciences START READING NOTES Study Radiographic Imaging Science using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. Contents of This Topic DUPLITEZED FILM Advantages of duplitized fil Radiographic Imaging Science Disadvantage Photographic characteristics of x ray film Photographic density Radiographic Density Factors affecting density Contrast Film contrast Film contrast depends on four Characteristics curve Film density is plotted on the vertical axis and Film latitude Cross over exposure Spatial resolution Noise Density is expressed as a number that is actually a logarithm, using the common base 10. Refer to Figure 11-1. If ten arrows (photons) Higher density means a blacker film (less Typical characteristic curve of a Cross over exponsure The ideal way to reduce print-through RADIOGRAPHIC IMAGING SCIENCE DUPLITEZED FILM The duplitizing of film is a method of gaining the benefits of increased emulsion thickness with few of the drawbacks. Duplitized film is designed for use with two intensifying screens and is still the most commonly used type of X-ray film in the X-ray department. Advantages of duplitized fil (1) Increased sensitivity, i.e. adequate image density can be achie\'ed from a smaller radiation exposure. This has two important consequences: (a) Radiation doses to patients and staff are reduced; (b) Wear on the X-ray tubes is reduced, thus extending their working life. Radiographic Imaging Science Increased image contrast: the contribution made by film emulsion to the eventual contrast of the image is greater because of the greater effective emulsion thickness. Disadvantage (1) Loss of image quality: the use of a duplitized film and twin-screen system may introduce a loss of image quality compared with other image recording systems. For example, the crossover of light from each intensifying screen to the emulsion on the 'wrong' side of the film leads to a loss of sharpness in the image. Radiographic Imaging Science (2) Economic reasons: duplitized films use a higher coating weight of silver than single-coated films, and silver is an expensive and diminishing world resource. Photographic characteristics of x ray film Exposure is proportional to the product of the milliamperes of x-ray tube current and the exposure time. Thus, an exposure of 100 milliamperes for 1 second is expressed as 100 milliampere-seconds, usually written 100 mAs. Radiographic Imaging Science Exposure (mAs) of the x-ray film produces film blackening, or density. The quality of the x-ray beam (kVp) has more effect on image contrast. mAs controls film density kVp controls image contrast Photographic density When the x-ray beam passes through body tissues, variable fractions of the beam will be absorbed, depending on the composition and thickness of the tissues and on the quality (kVp) of the beam. defines an image as "a mental representation of anything not actually present to the senses." Radiographic Density Density is the amount of the overall blackness produced on the image after processing A radiograph that is too light has insufficient density to visualize anatomic structures while if its too dark, has excessive density and anatomic parts can not be visualized. Factors affecting density X-ray Absorption: Dense structures like bones absorb more X-rays, resulting in brighter areas on the image. In contrast, softer tissues absorb fewer X-rays and appear darker. Exposure Settings: The amount of radiation exposure (controlled by mAs – milliampere-seconds) directly affects image density. Higher mAs produces darker images, while lower mAs produces lighter images. Radiographic Imaging Science the degree of film blackening is directly related to the intensity of radiation reaching the film or intensifying screen. The measurement of film blackness is called "photographic density“ Radiographic Imaging Science Higher density means a blacker film (less light transmission). In routine x-ray work, a density of 2 (1% of light transmitted) is black when viewed on a standard view box, and a density of 0.25 to 0.3 (50% of light transmitted) is very light. Radiographic Imaging Science The important part of them characteristic curve is between the toe and shoulder, and in this region the curve is almost a straight line. In this "straight line“ portion the density is approximately proportional to the log relative exposure. Contrast Contrast is the degree of difference between adjacent densities. It is the photographic density difference between two adjacent areas on a film/image The ability to distinguish between densities enables differences in anatomical tissues to be visualized. Contrast can be evaluated best when the radiographic density is adequate to visualize density differences Radiographic Imaging Science Radiographic contrast depends on subject contrast and on film contrast. Subject contrast depends on the differential attenuation of the x-ray beam as it passes through the patient. Subject contrast was seen to be affected by the thickness, density, and atomic differences of the subject, the radiation energy (k V p ), contrast material, and scatter radiation. Radiographic Imaging Science The radiographer is required to understand the anatomic structure to be radiographed for him/her to determine the factors required to achieve desired level of radiographic contrast. Factors affecting contrast; Kilovoltage Grids Collimation Object to Image receptor distance Anatomic part Contrast media Processing Film contrast Radiographic contrast is the density difference between image areas in the radiograph. There are many definitions of contrast, but we will use the simple definition that contrast is the difference in density existing between various regions on the film. Film contrast depends on four factors: characteristic curve of the film film density screen or direct x-ray exposure film processing Characteristics curve Is the relationship between the exposure a film receives and the density produced by the exposure. Radiographic Imaging Science The relationship between exposure and density is plotted as a curve, known as the "characteristic curve" or "H and D curve" (named after F. Hurter and V.C. Driffield, who first published such a curve in England in 1890). The concept of the characteristic curve of an x-ray film exposed by light from x-ray intensifying screens is illustrated in Figure 11-4. Film density is plotted on the vertical axis and film

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Processing Chemicals CRT04105 · Radiographic Imaging Sciences START READING NOTES Study Processing Chemicals using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. Contents of This Topic PROCESSING CHEMICALS LATENT IMAGE LATENT IMAGE CONT. LATENT IMAGE FORMATION LATENT IMAGE FORMATION cont. Its primary purpose is convert latent image into visible image CHEMICAL ACTION OF DEVELOPER Chemical Action of Developer cont.. EFFECTS OF THE BY-PRODUCTS OF DEVELOPMENT CONSTITUTION OF DEVELOPER SOLUTION CONSTITUENTS OF DEVELOPER REPLENISHER SOLUTION SOLVENT – WATER DEVELOPING AGENTS DEVELOPING AGENTS Cont .. ADVANTAGES OF PQ DEVELOPER Advantages of PQ Developer cont… The shape of the characteristic curve is controlled by the two developing agents developer…. ACCELERATORS developer…. Accelerators cont… developer…. BUFFERS developer…. RESTRAINERS PRESERVATIVES SEQUESTERING AGENTS STARTER SOLUTION EFFICIENCY OF DEVELOPMENT & FACTORS AFFECTING DEVELOPMENT HOW CONSTITUTION OF THE DEVELOPER AFFECT DEVELOPMENT? HOW DOES DEVELOPER TEMPERATURE AFFECT DEVELOPMENT? EFFECT OF INCREASE OF TEMPERATURE EFFECT OF DECREASE OF TEMPERATURE DEVELOPER TEMPERATURE IN MANUAL PROCESSING DEVELOPMENT TIME DEVELOPMENT TIME IS DETERMINED BY: Development is the most important part of processing KEY POINTS FIXING (FIXATION) Fixing (fixation), cont… CONSTITUENTS OF FIXING SOLUTION Constituents of Fixing Solution cont… Constituents of Fixing Solution, Chemical reaction cont… Constituents of Fixing Solution cont…ACID Constituents of Fixing Solution cont…HARDENER Constituents of Fixing Solution, Hardener cont… Constituents of Fixing Solution, BUFFER Constituents of Fixing Solution, PRESERVATIVE Constituents of Fixing Solution, ANTI-SLUDGING AGENT Fixing, cont… FACTORS AFFECTING FIXATION Fixing, cont… FACTORS INFLUENCING QUANTITY & QUALITY OF FIXING Fixing…Factors Influencing Quantity & Quality of Fixing: 1.FIXER CONSTITUTION Fixing… Factors Influencing Quantity & Quality of Fixing…1.Constitution cont… Fixing… Factors Influencing Quantity & Quality of Fixing…2. FIXER TEMPERATURE Fixing… Factors Influencing Quantity & Quality of Fixing…3. FIXING TIME Fixing… Factors Influencing Quantity & Quality of Fixing…3. Fixing Time cont… Fixing… Factors Influencing Quantity & Quality of Fixing…3. Fixing Time , Determining Factors cont… Fixing… MAINTENANCE OF FIXER VOLUME Fixing… FACTORS AFFECTING FIXER REPLENISHMENT RATE RINSING, WASHING & DRYING RINSING, WASHING & DRYING: 1. RINSING Rinsing, Washing & Drying: Rinsing cont… Rinsing, Washing & Drying: 2. WASHING Rinsing, Washing & Drying: 2. Washing: FACTORS AFFECTING WASHING EFFICIENCY Rinsing, Washing & Drying: 3. DRYING Rinsing, Washing & Drying: 3. Drying, cont… Rinsing, Washing & Drying: 3. Drying, FACTORS ON DRYING TIME Rinsing, Washing & Drying: 3. Drying… Factors on Drying Time cont… PROCESSING STAGES MANUAL FILM PROCESSING Manual Film Processing, cont…. Manual Film Processing…THE CYCLE Manual Film Processing…The Cycle cont… Manual Film Processing…STOP BATH/RINSING Manual Film Processing…Rinsing/Stop Bath, cont… Manual Film Processing…REPLENISHMENT PROCESSING CHEMICALS PROCESSING CHEMICALS The primary purpose of a radiographic processing is to deposit enough black metallic silver at the latent image sites to permit a permanent visible image to form The development of latent image can be accomplished manually or with automatic processing equipment.The development and fixing are accomplished in a solution of numerous chemicals LATENT IMAGE The silver bromide crystals consist of positive silver and negative ions arranged in geometrical pattern known as a crystal lattice When silver bromide grain is exposed to light or x-ray some of the bromide ions in the lattice emit electrons Electrons are trapped in the electron- trap in the crystal An electron trap is a region of low energy called a sensitivity speck producing during manufacture Electrons tend to collect at sensitivity speck and they confer on speck a negative charge A crystal lattice LATENT IMAGE CONT. Silver ions in the crystal have a positive charge, the silver which are free to move are attracted to the negative charge electrons in a sensitivity speck The negative charge on the electrons neutralises the positive charge on the silver ions; hence forming silver atoms LATENT IMAGE FORMATION How the film works Latent: Hidden – as the silver halide crystals are exposed to electromagnetic radiation, they are ionized and conversion to metallic silver is begun. This is completed in the processor LATENT IMAGE CONT. HOW THE FILM WORKS CONT. Sensitization speck Impurities/imperfections intentionally introduced to crystals during manufacturing. Found on surface of crystal Acts as electron trap, trapping electrons released during ionization of crystals. Essential for development of black metallic silver LATENT IMAGE FORMATION The latent image is theorized as being formed in the following manner: Radiant energy (x-ray photon or light photon from screen) strike the crystal & liberates an electron from the valence shell of a bromide ion. This electron is then free to move about in the crystal. If it strikes a sensitivity speck, it may be trapped giving the speck a negative charge. When a positive silver ion comes within the negative field of the speck, it may be attracted to the speck & take on an electron thus forming an atom of metallic silver LATENT IMAGE FORMATION cont. Occurs many times within the same crystal when struck by radiant energy. Once the film has been exposed to radiant energy & a latent image has been formed, the film is capable of developing a radiographic image. Chemicals in the processor greatly enhance this chemical reaction converting a latent image to a visible image LATENT IMAGE FORMATION cont. IN SUMMARY Electrons (released by light from bromine ions) are trapped Positive silver ions are trapped at the sensitivity speck by the negative charges on the electrons Positive charges on the silver ions are neutralized by negative charges on the electrons and silver atoms form Processing Chemicals Film Processing is a predetermined sequence of chemical treatment of the exposed film whereby the latent image is transformed into a visible image in a dry film. CHEMICALS IN AUTOMATIC PROCESSOR Four stages in Automatic processing namely Development, Fixing, Washing and Drying Developing:- it is the first step in processing film, at this stage silver is deposited at the latent image site and an image becomes visible. Processing Chemicals The deposition of silver amplifies the density of the image, a modern x-ray developers are capable of amplifying the image by a factor of 108 to 10 9 within 3-4 mins . Its primary purpose

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Imaging Science Session CRT04105 · Radiographic Imaging Sciences START READING NOTES Study Imaging Science Session using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. Contents of This Topic Image acquisition elements Demonstrate skills in manual image processing Describe film characteristics Explain human risk associated with the use of chemical image processing Distinguish automatic against computed radiography imaging processing Distinguish computed radiography and digital imaging Conduct image quality control test Demonstrate procedures in DIGITAL SYSTEM CHALLENGES Image acquisition elements Radiographic film (film construction) Intensifying screen types Characteristics, Cassettes, Types of chemicals, Processing tanks, (Types of processing system) Darkroom layout, safe light, film storage Demonstrate skills in manual image processing Load and unloading cassette, Naming film, Developing image sorting Describe film characteristics Sensitometry, Film latitude, Image density, Contrast details, Sharpness, Resolution, Distortion, Artefacts) Outline advantages and disadvantages of chemical film processing Explain human risk associated with the use of chemical image processing Explain images problems associated with the use of chemicals (Fog, under and over development, artifacts, increase cost due to film/chemical waste) Explain patient problems associated with the use of chemical processing (wrong diagnosis, repeat images, excessive dose to patients, time wastage) Distinguish automatic against computed radiography imaging processing Describe procedures of automatic and computed radiography image processing Describe quality assessment of images processed in automatic and computed radiography Enumerate advantages and disadvantages of automatic and computed radiography image processing Describe image communication mechanisms in automatic and computed radiography system Distinguish computed radiography and digital imaging Outlined steps in digital Imaging Outline advantages and disadvantages of digital imaging system Conduct image quality control test ID Orientation, Density, Contrast, Details, Sharpness, Resolution, Distortion Demonstrate procedures in Pictured Archiving and Communication System (PACS) Digital Imaging Communication in Medicine (DICOM) and Radiology Information System (RIS) DIGITAL SYSTEM CHALLENGES List challenges of digital imaging in terms of equipment acquisition and maintenance Outline user challenges in digital imaging Explain ways of overcoming the challenges ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Imaging Process CRT04105 · Radiographic Imaging Sciences START READING NOTES Study Imaging Process using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. RADIOGRAPHIC IMAGING SCIENCES OBJECTIVES Expected learning outcomes: At the end of the course/module students will be able to: Understanding photographic procedures in managing manual film production Determining risk associated in use of chemicals for image processing. To apply automatic and computer radiography technique in processing radiographic image To understand radiology image processing concept in digital imaging process. Understand use of digital film processing procedures in digital imaging production To determine the challenges associated in use of digital image processing. IMAGING PROCESS What is imaging process? Imaging Process Definition Introduction and overview of imaging processing (Convention, CR and DR) ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Image Artifacts – Imaging CRT04105 · Radiographic Imaging Sciences START READING NOTES Study Image Artifacts – Imaging using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. Contents of This Topic IMAGE ARTIFACTS occur in three areas: Exposure Artifacts Processing Artifacts Handling & Storage Artifacts occur Exposure artifacts are a result of examination technique. Image Artifacts – Imaging Chemical Fog Pressure or Kink Marks Static Hypo Retention Wet-Pressure Sensitization IMAGE ARTIFACTS IMAGE ARTIFACTS An artifact is any irregularity on an image that is not caused by the proper shadowing of tissue by the primary x-ray beam. Screen-film radiographic artifacts can interfere with the visualization of anatomical structures and can lead to misdiagnoses. Artifacts can be controlled when their cause is identified. Generally, radiographic artifacts occur in three areas: occur in three areas: exposure, processing, and handling. Exposure Artifacts Motion Improper patient position Wrong screen-film match Poor screen contact Double exposure Warped cassette Improper grid position Processing Artifacts Emulsion pickoff Gelatin buildup Curtain effect Chemical fog Guide-shoe marks Pi lines Wet pressure sensitization Dichroic stain Handling & Storage Artifacts Light fog Radiation fog Static Kink marks Hypo retention stain Scratches Artifacts occur (1) during the radiographic exposure, (2) during processing of the film, (3) when the film is being handled and stored before or after processing. Exposure artifacts are a result of examination technique. These include patient motion, positioning errors, wrong screen-film combinations, double exposures, and improper grid positioning. Image Artifacts – Imaging Processing artifacts are most often pressure blemishes on the film emulsion caused by the roller transport system in the processor. They include sludge from dirty rollers, chemical fog, roller marks, and wet-pressure sensitization. The most bothersome handling and storage artifacts are those associated with light or radiation fog, kink marks, and static. Chemical Fog Chemical fog looks like light or radiation fog and is usually a uniform dull gray. Improper or inadequate processing chemistry can result in a special type of chemical fog called a dichroic stain. Dichroic means two colors. The dichroic stain appears as a curtain effect on the radiograph (Figure 19-5). Dichroic stain is a term that is generally applied to all chemical stains. Pressure or Kink Marks Characteristic artifacts can be caused by improper handling or storage either before or after processing. Rough handling before processing can cause scratches and kink marks, such as those shown in Figure 19-7. Although the kink mark may appear as a fingernail mark, it is not. It is caused by the kinking or abrupt bending of film. Both events usually appear as increased OD. Static Static is probably the most obvious artifact. It is caused by the buildup of electrons in the emulsion and is most noticeable during the winter and during periods of extremely low humidity. Three distinct patterns of static are crown, tree, and smudge. Tree static Hypo Retention The yellow-brown stain that slowly appears on a radiograph after a long storage time indicates a problem with hypo retention from the fixer. With this event, not all of the residual thiosulfate from fixing was removed during washing, and silver sulfide slowly builds up and appears yellow in the stored radiograph. Wet-Pressure Sensitization Wet-pressure sensitization is a common artifact that is produced in the developer tank (Figure 19-6). Irregular or dirty rollers cause pressure during development and produce small circular patterns of increased OD. ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Film Processing CRT04105 · Radiographic Imaging Sciences START READING NOTES Study Film Processing using the sections below. Use the topic navigation to continue through Radiographic Imaging Sciences. Contents of This Topic Manual processing AUTOMATIC PROCESSING Electrons (released by light from bromine ions) are trapped RE: Temperature is quoted in Celsius (ºC) PROCESSING CHEMICAL All chemicals should be kept at same temperature. PROCESSING CYCLE DEVELOPMENT CHEMICAL ACTION OF DEVELOPER Charge barriers; EFFECTS OF THE BY-PRODUCTS OF CONSTITUTION OF DEVELOPER Developer replenisher CONSTITUENTS OF DEVELOPER SOLVENT – water DEVELOPING AGENTS PHENIDONE HYDROQUINONE Advantages of PQ developer NB; The shape of the characteristic curve is controlled by the two developing agents Accelerators PH and development Buffers Restrainers Preservatives Hardeners Sequestering agents Other constituents Starter solution Efficiency of development & Factors affecting development How Constitution of the developer Therefore the developer has to be replenished continuously if the activity is to be maintained HOW DOES DEVELOPER TEMPERATURE Effect of increase of temperature Effect of decrease of temperature Developer temperature in manual processing Development time Development time is determined by: Summary FIXATION Stopping further development Fixing the image Film Processing Constituents of fixing solution Fixing agents Chemical reaction that occurs in fixer Advantages of Ammonium thiosulphate over the sodium thiosulphate Acid Hardener Three Hardening agents used for fixing 2) Potassium Alum 3) Aluminium chloride (Aluminium sulphate) BUFFER PRESERVATIVE Anti-sludging agent FACTORS AFFECTING FIXATION Fixing agents:- Ammonium thiosulphate gives a rapid acting higher energy fixer 3.Presence of hardener:- Slow down the fixing process but speed up the drying process 5. Types of film material Factors affecting fixer replenishment rate Maintenance of fixer volume Fixing time FACTORS AFFECTING FIXING TIME RINSING, WASHING & DRYING PURPOSE OF INTERMEDIATE METHOD OF RINSING EFFECT OF INADEQUATE RISING WASHING EFFECT OF INADEQUATE WASHING DIFFUSION FACTORS AFFECTING WASHING c) Condition of washing water:- Wash water should be replaced frequently with fresh water DRYING Raising temperature of the air increases the rate at which moisture evaporates from gelatin and thus shortens drying time FACTORS AFFECTING DRYING TIME 2) The drying condition:- The drying medium is Air. DEVELOPER CHEMISTRY FOR AUTOMATIC PROCESSOR FIXER CHEMISTRY FOR AN AUTOMATIC PROCESSOR END OF CHAPTER QUESTIONS List 2 purpose of intermediate rinsing stage in manual processing FILM PROCESSING Manual processing Automatic processing FILM PROCESSING AUTOMATIC PROCESSING Four Automatic processing stages Development Fixing Washing Drying MANUAL PROCESSING Manual processing stages Development Rinsing Fixing Washing Drying LATENT IMAGE Electrons (released by light from bromine ions) are trapped Positive silver ions are trapped at the sensitivity speck by the negative charges on the electrons Positive charges on the silver ions are neutralized by negative charges on the electrons and silver atoms form RE: The effect on photosensitive materials (emulsion – Silver halides) of exposure to light or X-ray radiation is to produce an invisible latent image within the emulsion. The emulsion of X-ray films must be chemically processed to render visible and permanent the information recorded in the latent image. Film processing involves a number of complex chemical reactions whose activity and efficiency are influenced by various factors, including the temperature and acidity or alkalinity of the chemical environment in which the reactions take place. Temperature is quoted in Celsius (ºC) Acidity/ alkalinity is expressed using the pH scale. The pH scale Is used to express the degree of acidity or alkalinity of a solution. It is based on a measure of the concentration of the positively charged hydrogen ions in a solution. -In a neutral solution, such as pure water, these ions are present in equal numbers at a concentration of 10ˉ⁷ mol/l (moles per liter) -Increase in the concentration of hydrogen ions to > 10 ˉ⁷mol/1. The solution is then said to be acidic. -Concentration of hydrogen ions to < 10ˉ ⁷mol/l and the solution is then alkaline. PROCESSING CHEMICAL May be purchased in a variety of ways (liquids or powders). May be in concentrated form and need to be diluted or mixed. Preparing chemicals correctly is important or resulting solution may adversely affect the radiographic product. Chemicals should be kept at specified room temperature. Variances may adversely affect the radiographic product. Too low temps, some of the chemicals may become sluggish in action and produce an under-developed or under-fixed radiograph. Too high temps, may be too hot for manual control. All chemicals should be kept at same temperature. Variances in temperature between the chemicals can result in film reticulation. Reticulation- a darkroom artifact produced by variable chemical temperatures that cause irregular expansion and contraction of the film emulsion, resulting in a mottled density appearance PROCESSING CYCLE Manual processing Development Rinsing Fixing Washing Drying Automatic processing Development Fixing Washing Drying PROCESSING CYCLE MANUAL Exposed film Dev. Rinse Fix Wash Dryer PROCESSING CYCLE AUTOMATIC Exposed film Dev. Fix Wash Dryer DEVELOPMENT Its primary purpose is convert latent image into visible image During development the exposed silver halide grains are reduced to metallic silver while unexposed remain unchanged A chemical fog is produced by poor developer acting on unexposed grains CHEMICAL ACTION OF DEVELOPER Development is a process of chemical reduction; This reduction is achieved by developer donating electrons to silver ions in the grains, thus neutralizing their positive charge and converting them to metallic silver Both exposed and unexposed silver bromide grains are surrounded by –ve charge barrier of bromine ions employed during emulsion manufacture. CHEMICAL ACTION OF DEVELOPER The emulsion becomes wet Chemicals penetrate in to the emulsion A process of chemical reduction takes place Developer donates electrons to the silver ions in the exposed silver bromide grains Silver ions by obtaining electrons is converted into metallic silver Charge barriers; Both exposed and unexposed silver bromide grains are surrounded by a negative charge barrier of bromine ions created by the excess of potassium bromide employed in the synthesis of silver bromide during the manufacture of emulsion The charge barrier normally protects the silver bromide from attack by electrons in the developing solution Exposed silver bromide grains posses a weakness