Introduction to Radiologic Technology and Health Care Finals Reviewer PDF

**INTRODUCTION TO RADIOLOGIC TECHNOLOGY AND HEALTH CARE (WEEK 8)** **RADIOLOGY AS AN IMAGING SCIENCE** **TOPIC OUTLINE** - **The concept of Radiation** - The Language of Medicine: Radiographic Nomenclature - Properties of X-radiation - **The X-ray Machine** - Radiation P...

**INTRODUCTION TO RADIOLOGIC TECHNOLOGY AND HEALTH CARE (WEEK 8)** **RADIOLOGY AS AN IMAGING SCIENCE** **TOPIC OUTLINE** - **The concept of Radiation** - The Language of Medicine: Radiographic Nomenclature - Properties of X-radiation - **The X-ray Machine** - Radiation Production - Overview of X-ray tube component, parts, and basic circuitry **BASIC CONCEPTS** **Matter** - Defined as anything that occupies space and has shape or form. - Three basic forms: ***solid***, ***liquid*** and ***gas***. **Mass** - The quantity of matter that makes up any physical object **Atom** - Building blocks of matter **Atom** - **2 main parts**: ***Nucleus*** and ***Extranucleus*** - **3 fundamental particles**: ***Protons***, ***Electrons***, and ***Neutrons* (PEN)** - The neutrons and protons = form the nucleus of the atom - The electrons circle the nucleus in orbits called ***shells***. **Atom** - The useful model for visualizing atomic structure is that of the **solar system**, with the nucleus as the sun and the electrons as planets in orbit around the sun. - Miniature solar was first described by Niels Bohr in 1913 known as **Bohr's atom**.  **Electron** - Smallest & lightest particle - **Location**: Orbital shells - (-) charge - -1.602 x 10^-19^ - **Mass**: 9.1 x 10^-31^ kg. - **Atomic Mass Number:** 0 - Discovered by: **Joseph John Thomson** **Proton** - Most important particle - **Location**: Nucleus - (+) charge - **Mass**: 1.673 x 10^-27^ kg. - **Atomic Mass Number (A):** 1 - Discovered by: **Eugen Goldstein** **Neutron** - Heaviest and most unstable particle - **Location**: Nucleus - **Charge:** Electrically neutral - **Mass**: 1.675 x 10^-27^ kg. (Slightly heavier than that of proton) - **Atomic Mass Number (A):** 1 - Discovered by: **James Chadwick** **Law of Conservation** - Matter can be neither created nor destroyed, but it can change form. - Energy can be neither created nor destroyed, but it can change form. **Electron shells (Formula: 2n^2^** **)** - Maximum number of electrons that can occupy each electron shell  **Elements** - Substances made up of only one type of atom. **Molecules** - Two or more atoms may combine chemically. **Chemical Compound** - A substance that consists of only one type of molecule. - Ex. Water. Its chemical symbol is H~2~0, indicating that is made up of two atoms of hydrogen and one atom of oxygen. **Ionization** - Process when a neutral atom gains or loses an electron, the electric charges of its protons and electrons are no longer equal. **Energy** - Is defined as the ability to do work. - It occurs in several forms and can be changed from one form to another. **Forms of Energy** **Potential energy** - The ability to do work by virtue of position   **Kinetic energy** - The energy of motion. - It is possessed by all matters in motion. **Chemical energy** - It is the energy released by way of chemical reaction. **Electrical energy** - Represents the work that can be done when an electron or an electronic charge moves through an electronic potential. **Thermal (heat) energy** - Energy of motion at the atomic or molecular level and in this regard may be viewed as kinetic energy of atoms. **Electromagnetic energy** - Type of energy in x-ray just as matter can be transformed from one size, shape and form to another, so energy can be transformed from type to another. **ELECTROMAGNETIC ENERGY** - Moves through space at the velocity (speed) of approximately 186,400 miles/sec. - It takes in many forms **2 TYPES OF RADIATION** - **Ionizing Radiation** - Sufficient energy to remove an electron from its orbit. - X-rays are a form of ionizing radiation. - **Non-ionizing Radiation** - Does not have sufficient energy to remove an electron from its orbital shell. **2 Classifications of Radiation** - Electromagnetic Radiation - Particulate Radiation **Characteristics of Electromagnetic Radiation** - No Mass! - No Charge! - Constant Velocity: **3x10^8^ m/s (186,000 miles/s)** **Characteristics of Particulate Radiation** - Has mass! - Other term: ***Corpuscular Radiation*** **Parameters that describe EMR (FEW)** - **F**requency - The number of wavelengths that pass a point of observation per second. - It is the number of times per second that a crest passes a given point. - **E**nergy - **W**avelength - Distance from one crest to another.  **EMR** **Mnemonic**: **RMIVUXG** (Lowest to highest in energy and frequency EMR that ADDS the **UTMOST IMPORTANCE** to RADIOLOGY? - Gamma ray - X-ray - Visible light - Radio waves Their purpose? **PROPERTIES OF X-RAYS** - **X-rays are invisible**. In addition to being unable to see x-rays, one cannot feel, smell or hear them. - **X-rays are electrically neutral**. X-rays have neither a positive nor a negative charge; they cannot be accelerated or made to change direction by a manager or electrical field. - **X-rays have no mass**. X-rays create no resistance to being put into motion and cannot produce force. - **X-rays travel at the speed of light in a vacuum.** X-rays move at a constant velocity of 3 x 10^8^ m/s or 186,000 miles per second in a vacuum. - **X-ray cannot be optically focused**. Optical lenses have no ability to focus or refract x-ray photons - **X-rays form a polyenergetic or heterogenous beam**. The x-ray beam that is used in diagnostic radiography is composed of photons that have many different energy. The maximum energy that is set on the control panel of the radiographic unit by the radiographer. - **X-rays can be produced in a range of energies**. These are useful for different purposes in diagnostic radiography. The medically useful diagnostic range of x-ray energies is 30 to 150 kVp. - **X-rays travel in straight lines**. X-rays used in diagnostic radiography form a divergent beam in which each individual photon travels in a straight line. - **X**-**rays can cause some substances to fluoresce**. When x-rays strike some substances, those substances produce light. These substances are used in diagnostic radiography, such as image receptors. - **X**-**ray cause chemical changes to occur in radiographic and photographic film**. X-rays are capable of causing images to appear on radiographic film and are capable of fogging photographic film. - **X**-**rays can penetrate the human body.** X-rays have the ability to pass through the body, based on the energy of the x-rays and on the composition and thickness of the tissues being exposed. - **X**-**rays can be absorbed or scattered by tissues in the human body**. Depending on the energy of an individual x-ray photon, that photon may be absorbed in the body or be made to scatter, moving in another direction. - **X**-**rays can produce secondary radiation**. When x-rays absorbed as a result of a specific type of interaction with matter (photoelectric effect), a secondary or characteristic photon is produced. - **X-rays can cause chemical and biological damage to living tissue.** Through excitation and ionization (removal of electrons) of atoms comprising cells, damage to the cells can occur. 1. Are highly penetrating, invisible rays that are a form of electromagnetic radiation. 2. Are electrically neutral and therefore not affected by either electric or magnetic fields. 3. Can be produced over a wide variety of energies and wavelengths (polyenergetic and heterogeneous). 4. Release very small amounts of heat upon pass- ing through matter. 5. Travel in straight lines. 6. Travel at the speed of light, 3 x 108 meters per second in a vacuum. 7. Can ionize matter. 8. Cause fluorescence (the emission of light) of certain crystals. 9. Cannot be focused by a lens. 10. Affect photographic film. 11. Produce chemical and biological changes in matter through ionization and excitation. 12. Produce secondary and scatter radiation. **X-RAY PRODUCTION** **Introduction** - Diagnostic x-rays are produced in the target of the anode when high-energy projectile electrons are rapidly decelerated. - Diagnostic x-ray imaging equipment provides the means for practitioners to control the quality and quantity of the x-ray beam. **Introduction** - Consequently, it is important to understand the process of x-ray production and the factors that influence the characteristics of the beam. - Practitioners familiar with the concepts and factors that influence quality and quantity are better able to control exposure factors to produce optimal radiographic images while minimizing patient dose. **Electron Production** - In the x-ray tube, the purpose of the filament is to provide the free electrons necessary for x-ray production. - As the rotor is activated the current passing through the filament heats to the point where electrons boil off. This process is referred to as ***thermionic emission***. - At this point, a space charge (cloud of electrons) forms around the filament. The focusing cup temporarily concentrates the free electrons and helps form them into a beam. **Target Interactions** - Approximately 99% of the energy of projectile electrons converts into heat. - Only about 1% of the energy converts into x-ray photons. - Two types of interaction produce x-ray photons ***bremsstrahlung*** interactions and ***characteristic*** interactions. **Bremsstrahlung interaction** - To brake radiation or braking radiation. - Continuous radiation. - Occurs when projectile electrons pass by the outer shell of target atoms and interact with the force field of the nucleus of the atom. - Because of the nuclei are positively charged, there is a mutual attraction between them. - The nuclear force field causes the entering electron to slow down (or brake) and change direction.  **Characteristic interaction** - It occurs when projectile electrons interact with inner shell electrons of the target atoms. - Recall that orbital electrons within an atom have a specific binding energy. - The binding energy, based on the size of the atom and the shell in which the electron is located, is the energy that would be required to remove the electron from the atom. - Characteristic radiation is produced when projectile electrons with sufficient kinetic energy eject an inner orbital electron. **Characteristic interaction** - When this happens, the atom becomes unstable and temporarily ionized because of the missing electron. - An electron from an outer shell instantly fills and void created by the missing electron and an x-ray photon is emitted. - This process continues until the atom is stable. - The energy of emitted x-ray photon is equal to difference between the binding energy of the two involved orbital electrons. **Prime Exposure Factors** - kVp, mA exposure time. - The kVp affects both quality and quantity - mA and exposure time affect the quantity of the x-ray beam. **Kilovoltage peak (kVp)** - The kVp set by the practitioner determines the voltage or potential difference applied across the cathode and anode during the exposure. - This setting affects both quality and quantity of the x-ray beam. - kV setting controls the speed of electrons travelling from the cathode to anode. - An increase in kVp causes greater attraction of electrons towards the anode. This increased speed means projectile electrons possess greater potential energy. **Milliamperage (mA) and exposure time** - The mA set by the practitioner determines the quantity of electrons in the tube current. - The relationship between mA and quantity of x-ray photons produced is directly proportional. - As mA is increased, the quantity of electrons in the tube current and the number of x-ray photons increases proportionally and vice versa. **Milliamperage (mA) and exposure time** - The exposure time set by the practitioner controls the length of time electrons are permitted to travel from the cathode to the anode. - The relationship between exposure time and the quantity of x-ray photons produced is directly proportional. - As exposure time is increased, the quantity of electrons and the number of x-ray photons increases proportionally and vice versa. **Summary** - The quantity of electrons that travel from the cathode to the anode and the quantity of x-ray photons produced are directly proportional to the mA and exposure time. - The milliampere-second (mAs) is the product of mA and exposure time. - The mAs affects only the quantity of photons in the x-ray beam; it does not affect the quality or energy of the x-ray photons. **THE X-RAY MACHINE**  **X-RAY TUBE** - Device for generating x-rays by accelerating electrons to a high energy by an electrostatic field and making them strike a metal target either in a tube containing a low-pressure gas or, as in modern tubes, in a high vacuum x-ray tube. **TWO MAIN PARTS OF X-RAY TUBE** - **Cathode**\ (-) side of the X-ray tube - **Anode**\ (+) side of the X-ray tube **The Cathode Assembly** **Cathode Assembly** - Consists of the *filament*, *focusing cup*, and *associated wiring*. **Filament** - A small coil of thin Thoriated tungsten wire. The filament is where the electrons for the production of x-Rays are emitted. **Characteristics of the Cathode and the Anode**   **Cathode** - It is essential to have at least one filament for x-ray production; modern multipurpose x-ray tubes are dual-focus (they contain two filaments) - Each filament is situated in a hollow area in the cathode called a focusing cup (slight negative charge). - The shape of the focusing cup and its negative electric charge cause the electrons to be repelled in the direction of a very precise area on the target called the ***focal spot***. **Anode** - The vast majority of the energy of the electron stream is converted into heat. - This energy conversion takes place at the target. - Constructed to dissipate heat. - Excellent material for x-ray tube targets because it has a very high melting point and it is efficient at conducting heat away from the anode. - Early x-ray tubes had and current dental tubes have a solid, stationary copper anode with a slanted tungsten face. - Modern tubes for radiography have a ***rotating anode***. - The rotating anode is in the form of a disk, with a beveled-edge target. **Focusing Cup** - The filament is set centrally in a slot machined into a metal focusing cup: *the cathode cup*.  **The Anode Assembly** - Consists of the ***anode***, ***stator***, and ***rotor***. The anode is positively charged so that the electrons from the filament (cathode) are attracted to it to produce x-rays. The rest of the anode assembly is there so that the anode can rotate and have a bigger target for the electrons. - **Stator**: The stator is the stationary part of an electric motor or alternator. Depending on the configuration of the motor the stator may act as the field magnet, interacting with the armature to create motion. The stator consists of series of electromagnets equally spaced around the neck of the tube. - **Rotor**: The rotor is the non-stationary part of a rotary electric motor or alternator, which rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotor\'s axis. **Purpose of Anode**: - Serves as a target surface for the high-voltage electrons - Conducts the high-voltage from the cathode back into the x-ray generator circuit. - Serves as the primary thermal conductor. - **Stationary Anode**: An anode assembly that is immobile. - **Rotating Anode**: An anode assembly that turns during exposure. **Properties of Tungsten**: - **Proton (atomic) number** 74 -- the higher the proton number of the target the greater the amount of the target the greater the amount of radiation that will be produced for a given tube voltage and current. - **High melting point** --3400^0^C means it can withstand the high temperatures involved without melting and with little distortion. - **Electrical conductivity** -- the anode is required to conduct the tube current. - **Thermal conductivity** -- the target needs to dissipate the large amounts of heat produced. - Molybdenum (42) is used for soft tissue imaging. **The Envelope** - The envelope is the glass housing that protects the tube. - It is also used to help protect from excessive exposure to x-rays. - The envelope is the first part of the filtration system.  **Protective Housing** - The housing controls leakage and scattered radiation, isolates the high voltages, and provides a means to cool the tube. - **Leakage Radiation**: Any photons that escape from the housing except at the port. Leakage radiation must not exceed 100 mR/hr at 1 meter. **X-RAY EQUIPMENT** **X-ray Table** - Designed to support the patient in a position that will enhance radiographic examination. - Tabletop must be *uniformly radiolucent* to easily permit x-rays to pass through. - Tabletop must be ***easily cleaned***, ***hard to scratch***, and ***without crevices*** where radiographic contrast media can accumulate. - Must include space for a tray to hold cassettes and a radiographic grid. - Tables are available in *fixed* and *tilting* models. **X-ray Table** - Ancillary equipment for tilting tables includes a **footboard** for patients to stand on when the table is upright. - Footboard is often used for gastrointestinal studies when the patient begins the examination in an erect position. - **Shoulder supports.** Keep patients from sliding off the table. - **Handgrips**. Give the patient an added feeling of security. **X-ray Table** - Ancillary equipment for tilting tables includes a **footboard** for patients to stand on when the table is upright. - Footboard is often used for gastrointestinal studies when the patient begins the examination in an erect position. - **Shoulder supports.** Keep patients from sliding off the table. - **Handgrips**. Give the patient an added feeling of security. **TUBE SUPPORT** **Overhead Suspension System** - Sometimes called ***ceiling suspension***, allows controls of longitudinal and transverse positioning as well as vertical distance. **Floor-to-ceiling Suspension System** - Uses a pair of rails, one on the ceiling and one on the floor, for longitudinal positioning. - Rooms with extremely high ceilings may use an overhead rail suspended from a wall. **Floor Suspension System** - floor suspension system uses a tube-support column mounted on the floor. **X-RAY IMAGING SYSTEM** **Console** - The part of the machine that the operator controls the operation of the x-ray machine. - All machine consoles are a little different but there are always similarities. - The console is where we control x-ray tube current and voltage. **kV Adjustment** - Most consoles will have one or two knobs that change the taps on the autotransformer for major and minor kVp. - Modern units have LED readout of kVp. **Other Functions of Control Console** - The console will also have the exposure button or buttons. - The prep button is depressed to prepare the tube for exposure. **Exposure Button** - A green light will let you know that the machine is ready to make the exposure. - The exposure button is then depressed and the exposure is initiated. - The button must be held down until the exposure is complete. - If your finger slips off the button, the exposure is terminated. - The exposure control buttons are referred to as a "**Dead man Switch**"  **Exposure Button/Switch** - After the buttons are released, the rotor motor reverses and the rotor reduces speed. - During the exposure you will hear an audible tone so you will know that the exposure is in progress. **TYPES OF X-RAY MACHINES/ FACILITY** **X-RAY MACHINES** **Mobile X-ray Machine** - X-ray machine that is **PERMANENTLY MOUNTED ON WHEELS** and can be moved with reasonable ease. **Portable X-ray Machine** - X-ray machine that is capable of being carried by **NOT MORE THAN ONE ABLE-BODIED PERSON.** **Transportable X-ray Facility** - X-ray facility with an X-ray machine\ **PERMANENTLY MOUNTED** inside a **PROPERLY SHIELDED VEHICLE**.. **BASIC X-RAY CIRCUITRY** **BASIC CIRCUITRY** - X-ray machine employ many circuits for operation. - Three of these circuits form the basis of all operation: 1. ***The primary or low voltage circuit*** 2. ***The secondary circuit*** 3. ***The filament or heating circuit.*** - However, all of the electricity used in operating the x-ray equipment is obtained from a single source, the supply line. **PRIMARY CIRCUIT** - The primary circuit supplies: 1. ***The autotransformer*** 2. ***The primary side of the high-voltage transformer*** 3. ***The timing circuit*** 4. ***And many other low- voltage circuits necessary for the operation of the x-ray equipment.*** 1. ***line voltage regulator and meter*** 2. ***Autotransformer*** 3. ***pre reading voltmeter*** 4. ***milliampere selector, and*** 5. ***filament transformer.*** **Line Voltage Regulator** - Is a part of the primary side of the auto transformer and regulates the incoming voltage. **Line Voltage Meter** - Is in parallel with the supply line and shows the voltage delivered to the autotransformer. **Circuit Breaker** - Functions to ensure against overload of the delicate equipment of the x-ray machine, since it may be set to break at any desired load; it is quite easily reset. **Timers (Exposure)** - Are incorporated into the x-ray machine to initiate and to terminate the exposure. - **Automatic exposure control (AEC)** is a device that measures the quantity of radiation that reaches the image receptor. It automatically terminates the exposure when the image receptor has received the required radiation intensity. **SECONDARY CIRCUIT** - Begins and ends at the secondary side of the high-voltage transformer and conducts the high voltage used in the production of x-rays. **Exposure Switch** - Located in the primary circuit, automatically controls the secondary voltage and current, since they are obtained by mutual induction. **FILAMENT CIRCUIT** - The primary circuit supplies current to the filament circuit, which is frequently called the heating circuit. - The filament transformer induces the heating current, which flows through the cathode of the x-ray tube. - The heating current functions to produce sufficient heat in the cathode filaments to enable the secondary current through thermionic emission, to flow from the cathode to the anode. **INTRODUCTION TO RADIOLOGIC TECHNOLOGY AND HEALTH CARE (WEEK 9)** **IMAGING ACCESSORIES AND PROTECTIVE SHIELDS** **Imaging Accessories** **IMAGING ACCESSORIES** **Caliper** - The tool for body part measurement. - Main shaft of the caliper is a flat strip of metal, calibrated in both *inches* and *centimeters.* - There are two perpendicular extensions from the shaft: - One is permanently affixed to one end of the shaft and the other slides up and down the shaft. - These two extensions form "jaws" between which the body part is measured. **Caliper** - When a body part is measured, the fixed jaw of the caliper is placed under or against the part and the movable jaw is brought snugly and firmly against the patient on the opposite side. - You must take care that the jaws of the caliper remain parallel to each other. - **Remember**: ***A measuring caliper should be used to ascertain part thickness for accurate technique selection!*** **Intensifying Screen** - A sheet of plastic that is embedded with crystals called ***phosphors***. - When struck by radiation, phosphors glow with visible light. - This light from the phosphors exposes the x-ray film, which is sandwiched between intensifying screens in the lid and the base of the cassette. - Approximately 95% of the image on the film is made by light from the intensifying screens; only 5% of the image is made directly by the x-rays. **Cassette** - A rigid, light-tight container that holds the screens and film in close contact. **X-ray Film** - A sheet of *polyester plastic* coated with a thin layer of gelatin and silver compounds. - The image contained in the film is made visible by developing the film; the finished radiograph then becomes a permanent record of the examination and is considered a legal document. - The intensifying screens absorb the transmitted x-rays and produce light, which exposes the film. - Film manufactures produce film in a variety of sizes, ranging from 20 x 25 cm (8 x 10 inches) to 35 x 43 cm (14 x 17 inches).  **PARTS OF AN X-RAY FILM** **Construction** - **Supercoating** - **Emulsion** - **Adhesive Layer** - **BASE** **PARTS OF AN X-RAY FILM** - **Supercoating/Anti-Abrasive Layer** - Layer of hard, protective gelatin designed to protect the emulsion against mechanical damage that can arise from handling and transport within manual and automatic film loaders and processors. - Prevent glare when finished radiograph is viewed. - 2 -- 5 um thick **PARTS OF AN X-RAY FILM** - **Emulsion** - 5 -- 10 um (0.0002" -- 0.0004") thick - "Heart" of the x-ray film - **Binder: GELATIN** - Gives permanence to the emulsion. - Extracted from ***Collagen*** - Chemically considered as ***Colloid*** - **Recording medium: SILVER HALIDE CRYSTALS** - **Active ingredient** of the emulsion. **PARTS OF AN X-RAY FILM** - **Adhesive Layer (Substratum coating)** - Designed to glue the emulsion to the base. - Prevents bubble or other distortion when the film is bent during processing or handling, or when is wet or heated during development. **PARTS OF AN X-RAY FILM** - **Film Base:** Thin layer of polyester (polyethylene terephthalate), which transmits light and provides a support for the layers. - Foundation of the radiographic film. - It primary purpose is to provide a rigid structure onto which the emulsion can be coated. - Flexible and fracture-resistant to allow easy handling but rigid enough to be snapped into a viewbox. - Approximately 150 to 300 micrometer thick and it is made of **History of Radiographic Film Base** - **Glass plate** - The original film base used during World War I. - Severely limited - **Cellulose Nitrate (1914)** - Substitute material for glass plate - Disadvantage: *Flammable* - Improper storage and handling of some x-ray film files resulted in severe hospital fires during the 1920s and early 1930s. **Cellulose Triacetate (1924)** - Replaced cellulose nitrate in mid-1920s film with "*safety base*." - Less flammable - **Polyester (1960)** - Introduced as film base. - More resistant to warping with age - Stronger than cellulose triacetate, permitting easier transport through automatic processors. - Its dimensional stability is superior. - Made up of **ETHYLENE GLYCOL** & **DIMETHYL TEREPHTALATE** ***Blue dye is added*** - to enhance contrast - to reduce glare/eye strain - The base of radiographic film maintains its size and shape during use and processing so that it does not contribute to image distortion. - This property of the base is known as ***dimensional stability.*** **Positioning Sponges and Sandbags** - Commonly used as immobilization devices. **Pigg-O-Stat** - Commonly used as a pediatric immobilizer. - Excellent for holding a child safely in an upright position. - Useful for imaging procedures of the chest or upright abdominal exams. **Film Hangers** - Used during ***film processing*** to position and hold/suspend the film, eliminate streaking and maintain tension and alignment. - Manual processing **Lead Markers** - Usually made of lead and placed directly on the image receptor. - The marker is seen on the image along with the bodily part. - Every radiograph must contain a correct marker that clearly identifies the patient's right (R) or left (L) side. **Negatoscope or View box** - A device made of lights placed behind a translucent screen. - Used to provide backlighting for a radiographic image. - It helps clinicians see the brightness, contrast, and details of an image. - Also known as an ***illuminator*** **PROTECTIVE SHIELDS** **Protective Shields** - Lead goggles/glasses - Lead Gloves - Thyroid Shields - Gonadal Shields - Lead Apron **Lead Apron** - Reduces exposure of a patient to x-rays to vital organs that are potentially exposed to ionizing radiation during medical imaging procedures. **Lead Gloves** - If the radiographer\'s hands will be near the x-ray beam, protective lead aprons and leaded gloves should be used whenever the radiographer cannot remain behind a protective barrier during an exposure. **Lead Goggles/Eye glasses** - Scatter radiation to the lens of the eyes of diagnostic imaging personnel can be substantially reduced by the use of protective eyeglasses. **Thyroid Shields** - Can guard the thyroid area of occupationally exposed people during: - General fluoroscopy - X-ray special procedures **Gonadal Shields** - Shielding of the gonads (ovaries and testes) is especially important. - Minimize the possibility of any genetic effect on the future children of an exposed individual. - Four types of gonadal shields: ***Flat contact shields, Shaped contact shields, Shadow shields, and Clear Lead Shields*** **Gonadal Shields** - Used on patients during diagnostic x-ray procedures to protect the reproductive organs from exposure to the useful beam when these organs are in or within approximately 5 cm of a properly collimated beam. - Gonadal shielding is used unless it will compromise the diagnostic value of the examination. **Flat contact shields** - Made of various sizes or lead-impregnated vinyl - Placed between the patient's gonads and the source of radiation. - May need to be secured in place to ensure correct placement for a variety of patient positions. **Flat contact shields** - These shields are most effective when they are used as protective devices for patients having anteroposterior (AP) or posteroanterior (PA) radiographs while in a recumbent position. - If the flat contact shield is used during a typical fluoroscopic examination, it must be placed under the patient to be effective because the x-ray tube is located under the radiographic table.  **Shaped contact shields** - Cup-shaped - Designed to enclose the MALE gonads. - These shields provide maximum protection in a number of patient positions. **Shadow shields** - Mounted to the tube - Placed in the X-ray beam near the collimator. - The collimator's light field must be precise for accurate shield placement. - The device is adjusted to cast a shadow over the patient's gonads. **Clear Lead shields** - Some of the basic gonadal shielding devices such as the previously described shaped contact shield and first-generation, or earliest type of, shadow shield are being replaced by clear lead gonad and breast shielding. - ***These shields are made of transparent lead-acrylic material impregnated with approximately 30% lead by weight.*** **INTRODUCTION TO RADIOLOGIC TECHNOLOGY AND HEALTH CARE (WEEK 10)** **OTHER IMAGING MODALITIES/ SUB-SPECIALIZATIONS** **TOPIC OUTLINE** **Other Imaging Modalities** - 1\. Ultrasound (UTS/UTZ) - 2\. Fluoroscopy - 3\. Computed and Digital Radiography - 4\. Computed Tomography (CT-scan) - 5\. Magnetic Resonance Imaging (MRI) - 6\. Nuclear Medicine - 7\. Bone Densitometry - 8\. PET scan and SPECT scan - 9\. Radiation Therapy **IMAGING MODALITIES** **Ultrasound** - Uses high-frequency sound waves to form an image. - A person who specializes in this field is known as a diagnostic ***sonographer***. - In addition, a sonographer must have knowledge of the ultrasound machine, instrumentation, and how to produce quality images that show correct anatomical representation of the area being imaged. - Physicians rely heavily on the expertise of the sonographer in obtaining images necessary for proper diagnosis. **Fluoroscopy** - Dynamic, real-time radiographic examination, compared to diagnostic radiography, which is static in character. - Involves active diagnosis during an examination. - For this reason, fluoroscopy is primarily the domain of the radiologist. - The radiographer's role becomes that of an assistant during the examination, although routine post-fluoroscopic radiography is the responsibility of the radiographer. **Fluoroscopy** - The invention of the ***fluoroscope*** is credited to Thomas A. Edison in 1896, the year after Röntgen's discovery of x-rays. **Computed and Digital Radiography** - Digital radiography imaging systems replace traditional film with a reusable detector. - These systems are divided into two types generally known as ***computed radiography*** (CR) and ***digital radiography*** (DR). **Computed and Digital Radiography** - **Computed Radiography** - cassette is taken to a reader to process the plate and create the image. - **Digital Radiography** - typically have the detector and reader that are a permanent part of a table or wall unit - A cassette is not needed. - Newer technology has now made some of these systems wireless and they can resemble a sealed cassette that can be moved around a room **Digital Radiography** - Indirect - Direct  **Computed Tomography (CT -- Scan)** - Computed tomography (CT) produces a digital tomographic image from diagnostic x-rays. - Produces 2-D and 3-D cross-sectional images of anatomy. - This technology allows physicians to visualize patient anatomy in various sectional planes (Axial, Transverse, Coronal Planes). - CT involves the use of highly specialized equipment and complex procedures, which has resulted in a need for radiographers to be specially prepared in this advanced technology. **Magnetic Resonance Imaging (MRI)** - A medical imaging technique used in radiology to visualize detailed internal structures. - MRI makes use of the property of nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body. - Uses a powerful magnetic field to align the magnetization of some atoms in the body, and radio frequency fields to systematically alter the alignment of this magnetization. - This causes the nuclei to produce a rotating magnetic field detectable by the scanner---and this information is recorded to construct an image of the scanned area of the body. **Magnetic Resonance Imaging (MRI)** - MRI provides good contrast between the different soft tissues of the body. - Especially useful in imaging the brain, muscles, the heart, and cancers compared with other medical imaging techniques such as computed tomography (CT) or X-rays. - Unlike CT scans or traditional X-rays, MRI does not use ionizing radiation. **Bone Densitometry** - Bone densitometry (BD) is most often used to diagnose osteoporosis. - Osteoporosis involves a gradual loss of calcium, causing the bones to become thin, fragile and prone to fractures. - Routine x-ray examinations can diagnose bone fractures but are not best way to assess bone density. - To detect osteoporosis accurately, dual-energy x-ray absorptiometry (DEXA or DXA) is used. - DEXA BD is the current standard for measuring bone mineral density (BMD). Measurement of the lower spine and hips is most often performed. **Nuclear Medicine (SPECT and PET Scan)** - Involve the imaging of a patient's organs -- such as the liver, heart or brain -- after the introduction of a radioactive material known as ***radiopharmaceutical*** - Radiopharmaceuticals are used as tracers in nuclear medicine studies. - A tracer is a substance that emits radiation and that can be identified when placed in the human body. - By detecting the tracer, information about the structure, function, secretion, excretion and volume of a particular organ can be obtained. **Nuclear Medicine (SPECT and PET Scan)** - Radiopharmaceuticals are also used to perform positron emission tomography (PET) procedure. - PET scans create sectional images of the body demonstrate the physiologic function of various organs and systems. - The main difference between **SPECT and PET scans** is the type of radiotracers used. **Nuclear Medicine (SPECT and PET Scan)** - **SPECT** - uses gamma emitting radioisotope (tracer) - Lower cost - Technetium-99m - Iodine-123 - Iodine-131 - **PET** - uses positron emitting radioisotope (tracer) - Very costly/expensive - Fluorine-18 **Single Positron Emission Computed Tomography (SPECT)**  **Positron Emission Tomography (PET)**   **Radiation Therapy** - Often referred to as radiation oncology. - Synergistic with chemotherapy and has been used before, during, and after chemotherapy in susceptible cancers. - Commonly applied to the cancerous tumor because of its ability to control cell growth. - Ionizing radiation works by damaging the DNA of exposed tissue leading to cellular death. - Uses complex equipment such as Linear Accelerators (LINAC) and Brachytherapy unit **Radiation Therapy** - The medical specialty concerned with prescribing radiation for cancer treatment. - Radiation may be prescribed by a radiation oncologist with intent to cure (\"curative\") or for adjuvant therapy. - It may also be used as palliative treatment (where cure is not possible and the aim is for local disease control or symptomatic relief) or as therapeutic treatment (where the therapy has survival benefit and it can be curative). **Radiation Therapy** - To spare normal tissues (such as skin or organs which radiation must pass through in order to treat the tumor), shaped radiation beams are aimed from several angles of exposure to intersect at the tumor, providing a much larger absorbed dose there than in the surrounding, healthy tissue. **Radiation Therapy** - It is necessary to include a margin of normal tissue around the tumor to allow for uncertainties in daily set-up and internal tumor motion. - These uncertainties can be caused by internal movement (for example, respiration and bladder filling) and movement of external skin marks relative to the tumor position. **Radiation Therapy** - **Brachytherapy** - The radiation source is placed inside or next to the area requiring treatment, is another form of radiation therapy that minimizes exposure to healthy tissue during procedures to treat cancers of the breast, prostate and other organs.