Basic Concepts of Radiation
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Questions and Answers

What is the transfer of energy called?

Radiation

What is the removal of an electron from an atom called?

Ionization

Which of the following are examples of ionizing radiation?

  • X-rays (correct)
  • Ultrasound
  • Gamma rays (correct)
  • MRI

    • Which of the following is the largest source of natural environmental radiation?

    <p>Radon (D)</p> Signup and view all the answers

    Diagnostic x-rays are the largest man-made source of ionizing radiation.

    <p>True (A)</p> Signup and view all the answers

    The component of the x-ray imaging system that is rarely seen by radiologic technologists is the ______.

    <p>x-ray tube</p> Signup and view all the answers

    Which of the following are primary parts of an x-ray tube?

    <p>Anode (B), Cathode (D)</p> Signup and view all the answers

    What type of radiation contributes nothing to diagnostic information and can result in unnecessary exposure to the patient and radiologic technologist?

    <p>Leakage radiation</p> Signup and view all the answers

    What is the purpose of the glass or metal enclosure of an x-ray tube?

    <p>To withstand the tremendous heat generated, maintain a vacuum inside the tube, and protect the electrons of the tube current</p> Signup and view all the answers

    What is the purpose of the stator in an x-ray tube?

    <p>To provide a series of electromagnets around the neck of the tube</p> Signup and view all the answers

    What is the name of the coil of wire in an x-ray tube that produces electrons?

    <p>Filament</p> Signup and view all the answers

    What is the metal shroud that surrounds the filament in an x-ray tube called?

    <p>Focusing cup</p> Signup and view all the answers

    The anode is the negative side of the x-ray tube.

    <p>False (B)</p> Signup and view all the answers

    Which of the following are common anode materials?

    <p>Molybdenum (B), Graphite (C), Copper (D)</p> Signup and view all the answers

    What is the area of the anode struck by the electrons from the cathode called?

    <p>Target</p> Signup and view all the answers

    In a rotating anode tube, the entire rotating disk is the target.

    <p>True (A)</p> Signup and view all the answers

    What does the operating console allow the radiologic technologist to control?

    <p>The x-ray tube current and voltage</p> Signup and view all the answers

    What refers to the number of x-rays or the intensity of the x-ray beam?

    <p>Radiation quantity</p> Signup and view all the answers

    The operating console usually provides control for line compensation, kVp, mA, and exposure time.

    <p>True (A)</p> Signup and view all the answers

    What is the purpose of the high-voltage generator in an x-ray system?

    <p>To provide the high voltage required for the x-ray production</p> Signup and view all the answers

    Which of the following is not a source of electrons in an x-ray tube?

    <p>The anode (C)</p> Signup and view all the answers

    X-rays are stored in radioactive materials.

    <p>False (B)</p> Signup and view all the answers

    The radiographer manufactures an x-ray for each exposure using technical factors manipulated on the x-ray control panel.

    <p>True (A)</p> Signup and view all the answers

    Digital imaging equipment enhances images of the body.

    <p>True (A)</p> Signup and view all the answers

    In digital radiography, the density and contrast of the image cannot be altered after the completion of the study.

    <p>False (B)</p> Signup and view all the answers

    Which of the following is not a type of digital imaging?

    <p>Film-screen imaging (A)</p> Signup and view all the answers

    What is the name of the substance that is coated on the imaging plate (IP) in computed radiography (CR)?

    <p>Photostimulable phosphor</p> Signup and view all the answers

    In direct digital radiography (DR), the cassette is eliminated, and the imaging plate is replaced by an imaging plate that remains in place inside the x-ray table or wall Bucky.

    <p>True (A)</p> Signup and view all the answers

    The DR image appears on the monitor almost immediately.

    <p>True (A)</p> Signup and view all the answers

    What is the primary means of making a radiographic image that involves the use of film and intensifying screens called?

    <p>Film-screen imaging</p> Signup and view all the answers

    What is the purpose of the intensifying screen in film-screen imaging?

    <p>To reduce the amount of radiation needed for exposure</p> Signup and view all the answers

    The x-ray film is a sheet of polyester plastic that is coated with a thin layer of gelatin and silver compounds.

    <p>True (A)</p> Signup and view all the answers

    What is the imaging technique that provides a live-action view of the interior of the body?

    <p>Fluoroscopy (B)</p> Signup and view all the answers

    Digital fluoroscopy provides a live-action view of the interior of the body.

    <p>True (A)</p> Signup and view all the answers

    In fluoroscopy, the x-ray tube is located outside the x-ray table.

    <p>False (B)</p> Signup and view all the answers

    CT units provide cross-sectional views of the body.

    <p>True (A)</p> Signup and view all the answers

    CT greatly improves the accuracy of diagnoses.

    <p>True (A)</p> Signup and view all the answers

    In many cases, CT eliminates the need for exploratory surgery.

    <p>True (A)</p> Signup and view all the answers

    MRI units allow cross-sectional views of the body to be made without the use of ionizing radiation.

    <p>True (A)</p> Signup and view all the answers

    The body part in question in MRI is exposed to a magnetic field and radio wave transmission.

    <p>True (A)</p> Signup and view all the answers

    PET is similar to nuclear medicine in that it uses a radiopharmaceutical agent injected into the circulatory system to image the area of interest.

    <p>True (A)</p> Signup and view all the answers

    PET is used to evaluate both the physiological condition or function of an organ or system in the body and the structure of an organ.

    <p>True (A)</p> Signup and view all the answers

    In nuclear medicine, radioactive materials introduced into the body are used to produce images of major organs.

    <p>True (A)</p> Signup and view all the answers

    The radioactive material concentrates in the area of interest and emits radiation.

    <p>True (A)</p> Signup and view all the answers

    Portable radiography and fluoroscopy can be performed if the patient cannot be moved to the radiology department.

    <p>True (A)</p> Signup and view all the answers

    Mobile radiography units operate with battery power.

    <p>True (A)</p> Signup and view all the answers

    The quality of images of most anatomic structures is equivalent to those obtained in the radiology department.

    <p>True (A)</p> Signup and view all the answers

    Portable radiography is used primarily in the surgical department (OR).

    <p>True (A)</p> Signup and view all the answers

    Mobile fluoroscopy (C-arm) is used primarily in the OR, where the surgeon must see the images immediately.

    <p>True (A)</p> Signup and view all the answers

    Sonography uses high-frequency sound waves, which is a form of ionizing radiation, to obtain sectional images of the body.

    <p>False (B)</p> Signup and view all the answers

    The sound waves bounce off interior structures of the body and return as echoes to a probe.

    <p>True (A)</p> Signup and view all the answers

    Cross-sectional images and evaluation of moving organs can also be made with sonography.

    <p>True (A)</p> Signup and view all the answers

    Doppler technique is a type of sonography used to evaluate blood flow through the arteries.

    <p>True (A)</p> Signup and view all the answers

    Computed imaging procedures, such as DR, CT, NM, UTZ, and MRI, can be combined into a network. The picture archiving and communication system (PACS) brings digital imaging together with hospital and radiology information systems.

    <p>True (A)</p> Signup and view all the answers

    PACS allows for the total management of a patient's case.

    <p>True (A)</p> Signup and view all the answers

    Conventional radiographs can be digitized and also entered into the system.

    <p>True (A)</p> Signup and view all the answers

    Digital images and patient information from a computer network can be accessed from any workstation that is connected to the system.

    <p>True (A)</p> Signup and view all the answers

    Data are stored on optical disks.

    <p>True (A)</p> Signup and view all the answers

    Information can be transmitted from the computer storage device via cable throughout the hospital and vicinity or via satellite across the world.

    <p>True (A)</p> Signup and view all the answers

    Flashcards

    What is radiation?

    The transfer of energy through space without the need for a medium.

    What is ionizing radiation?

    Radiation that carries enough energy to remove an electron from an atom.

    What is non-ionizing radiation?

    Radiation that doesn't have enough energy to remove electrons from atoms.

    What are cosmic rays?

    Radiation emitted by the sun and stars, including particles and electromagnetic waves.

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    What is terrestrial radiation?

    Radiation originating from naturally occurring radioactive elements in the Earth.

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    What are internally-deposited radionuclides?

    Naturally occurring radioactive elements present within our bodies.

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    What is radon?

    A radioactive gas produced by the decay of uranium found in rocks and soil.

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    What is man-made radiation?

    Radiation produced by human activities, such as medical imaging or industrial processes.

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    What is particulate radiation?

    Radiation consisting of moving particles with enough kinetic energy to cause ionization.

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    What are alpha particles?

    Heavy particles emitted from the nuclei of atoms, composed of two protons and two neutrons.

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    What are beta particles?

    Light particles emitted from the nuclei of atoms, carrying one unit of negative or positive charge.

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    What is electromagnetic radiation?

    Radiation consisting of energy packets called photons, emitted from the nuclei of atoms or electron shells.

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    What are gamma rays?

    Electromagnetic radiation emitted from the nuclei of atoms, usually associated with alpha and beta emission.

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    What are X-rays?

    Electromagnetic radiation produced outside the nucleus of an atom, typically by bombarding a metal target with electrons.

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    What is an X-ray tube?

    The component of an X-ray imaging system that generates X-rays.

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    What is the cathode?

    The negative electrode in an X-ray tube, emitting electrons through thermionic emission.

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    What is the anode?

    The positive electrode in an X-ray tube, receiving electrons from the cathode and producing X-rays.

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    What is the filament?

    The coiled wire within the cathode that heats up and releases electrons through thermionic emission.

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    What is the focusing cup?

    A metal shroud surrounding the filament that helps focus the electron beam towards the anode.

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    What is the target?

    The part of the anode that is struck by electrons, producing X-rays.

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    What is the operating console?

    The part of the X-ray imaging system that controls the X-ray tube current and voltage to produce an appropriate X-ray beam.

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    What is the high-voltage generator?

    The component of an X-ray imaging system responsible for increasing the voltage needed to power the X-ray tube.

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    What is digital radiography?

    A type of imaging technology that uses X-rays to produce images of the inside of the body.

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    What is computed radiography (CR)?

    A type of digital radiography using a cassette containing a photostimulable phosphor imaging plate.

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    What is direct digital radiography (DR)?

    A type of digital radiography where the imaging plate is directly integrated into the X-ray table or wall Bucky.

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    What is fluoroscopy?

    A type of imaging technology that uses X-rays to create images of the inside of the body, displaying them live on a monitor.

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    What is computed tomography (CT)?

    A type of imaging technology that uses X-rays to create cross-sectional images of the body, revealing detailed internal structures.

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    What is magnetic resonance imaging (MRI)?

    A type of imaging technology that uses strong magnetic fields and radio waves to create detailed images of the inside of the body.

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    What is positron emission tomography (PET)?

    A type of imaging technology that uses a radioactive tracer to produce images of organs and their function.

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    What is nuclear medicine?

    A branch of medicine that uses radioactive substances to diagnose and treat diseases.

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    What is sonography (ultrasound)?

    A type of imaging technology that uses high-frequency sound waves to create images of the inside of the body.

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    What is a picture archiving and communication system (PACS)?

    A network system for storing, managing, and distributing digital medical images.

    Signup and view all the flashcards

    Study Notes

    Basic Concepts of Radiation

    • Radiation is the emission and transfer of energy through space.
    • Visible light is a form of electromagnetic energy, radiated by the sun.
    • Electromagnetic energy is also known as electromagnetic radiation, or simply radiation.
    • Radiation is the transfer of energy.

    Types of Radiation

    • Ionizing Radiation: Removes an orbital electron from an atom with which it interacts. This interaction is called ionization. Examples include X-rays, gamma rays, and particulate radiation (alpha and beta particles). Ionization is the removal of an electron from an atom.
    • Non-ionizing Radiation: Does not carry enough energy to completely remove an electron from an atom or molecule. Examples include MRI and ultrasound.

    Sources of Ionizing Radiation

    • Natural Environmental Radiation:
    • Cosmic Rays: Particulate and electromagnetic radiation from the sun and stars.
    • Terrestrial Radiation: Results from deposits of uranium, thorium, and other radionuclides.
    • Internally-deposited radionuclides: Primarily potassium-40, natural metabolites.
    • Radon: A radioactive gas produced by natural radioactive decay, the largest source of natural environmental radiation.
    • Man-made Radiation:
    • Diagnostic X-rays: The largest man-made source of ionizing radiation (3.2 mSv/yr) according to 2006 estimates by the National Council on Radiation Protection and Measurements (NCRP). Earlier estimates (1990) put this at nearly 0.4 mSv/yr.

    Types of Ionizing Radiation - Particulate

    • Alpha Particles: Equivalent to a helium nucleus; contains two protons and two neutrons. Emitted from heavy elements. Ionization accompanies alpha radiation. They possess 4 to 7 MeV of kinetic energy, and ionize approximately 40,000 atoms for every centimeter of travel through air. Range in matter is very short. Travel approximately 5 cm in air, but less than 100 µm in soft tissue.

    • Beta Particles: Differ from alpha particles in terms of mass and charge; are light particles with an atomic mass number of zero and carry one unit of negative or positive charge. Originate in the nuclei of radioactive atoms. Ionize several hundred atoms per centimeter. Range is longer than alpha particles. Can travel 10 to 100 cm in air and approximately 1 to 2 cm in soft tissue.

    Types of Ionizing Radiation - Electromagnetic

    • X-rays and Gamma rays: Photons with no mass or charge, traveling at the speed of light (3x108 m/s). Gamma rays originate from the nucleus of a radioisotope, while X-rays are produced outside the nucleus in electron shells. X-rays and gamma rays have unlimited range in matter; intensity reduces with distance but theoretically never reaches zero.

    The X-Ray Machine

    • The X-ray Imaging System has three main components: the x-ray tube, the operating console, and the high-voltage generator.

    X-Ray Tube

    • The x-ray tube is contained in a protective housing.
    • Two primary parts: cathode and anode.
    • Three external structures: support, housing, and enclosure (glass or metal).

    Protective Housing

    • X-Ray leakage radiation that escapes through the protective housing.
    • Protective housings are designed to reduce leakage radiation to less than 1 mGy/hr (milligray per hour) at 1 meter.

    Glass or Metal Enclosure

    • Pyrex glass to withstand generated heat.
    • Maintains a vacuum inside to allow efficient x-ray production and prolong tube life.
    • Metal encloses the tube to maintain constant electric potential between electrons of the tube current and the enclosure.
    • Stator consists of electromagnets equally spaced around the tube neck
    • Rotor is constructed of bars of copper and soft iron

    Cathode

    • Filament coil, similar to a toaster, but smaller (2mm diameter and 1-2cm length).
    • Made of thoriated tungsten (1-2% thorium) for improved thermionic emission efficiency and longer tube life.
    • Thermionic emission: "boiling off" of outer-shell electrons from the filament when sufficient current passes through it.
    • Tungsten vaporization with deposition in the enclosure is a common cause of tube failure.

    Focusing Cup

    • Metal shroud surrounding the filament, negatively charged.
    • Electrostatically confines the electron beam to a small area on the anode.
    • Prevents electrostatic repulsion of the electron beam.

    Anode

    • Electrical conductor that receives electrons emitted from the cathode.
    • Provides mechanical support for the target, and must be a good thermal dissipater.
    • Common materials: copper, molybdenum, and graphite.

    Target

    • Area of the anode struck by electrons from the cathode.
    • Stationary anode tubes: tungsten alloy embedded in the copper anode
    • Rotating anode tubes: the entire rotating disc is the target.

    Operating Console

    • Allows the radiologic technologist to control x-ray tube current and voltage for appropriate beam quality and quantity.
    • Handles radiation quantity (number of x-rays, intensity of beam) control.
    • Usually controls: line compensation, kVp, mA, and exposure time.

    High Voltage Generator

    • Powers the x-ray tube.
    • Increases the output voltage (kVp).
    • Usually runs on single phase to reduce voltage ripples.

    Imaging Equipment:

    • X-Ray Tube: X-rays produced through electron-energy conversions; source of electrons, means to accelerate them, and means to abruptly stop them.
    • Digital Imaging: Images are enhanced, density and contrast can be altered after the study, and images can be stored and transferred via computer network.

    Computed Radiography (CR):

    • Imaging plate (IP) coated with photostimulable phosphor.
    • Radiation excites the IP.
    • Laser scan releases energy, converts to a visible image.
    • Results displayed on a high-resolution monitor.

    Direct Digital Radiography (DR):

    • Eliminates cassettes.
    • Images displayed on a monitor almost immediately.
    • No need to handle cassettes.

    Film-Screen Imaging:

    • Intensifying screens with phosphors convert x-rays to visible light.
    • This light exposes the x-ray film.
    • Film is made of polyester plastic, coated with gelatin and silver compounds.
    • Processed film creates a permanent record
    • Used in the past.

    Fluoroscopy:

    • Live-action view of the body's interior on a monitor.
    • X-ray tube is typically located inside the x-ray table
    • Image intensifier brightens and enhances the image, which is then transmitted to the monitor.

    Computed Tomography (CT):

    • Cross-sectional views of the body.
    • X-ray tube and detector rotate around the patient's body.
    • Computer reconstructs the information into an image
    • Eliminates the need for exploratory surgery in many cases and improve accuracy of diagnoses.

    Magnetic Resonance Imaging (MRI):

    • Cross-sectional views of the body without ionizing radiation.
    • Patient lies on a couch inside a cylindrical imager.
    • Body part is exposed to a magnetic field and radio waves.
    • Computer reconstructs the signals into images, which provide data on both anatomy and physiological characteristics.

    Positron Emission Tomography (PET):

    • Evaluates the physiologic condition or function of organs or systems.
    • Uses a radiopharmaceutical injected into the body.
    • Radiation emitted from the body and detected by sensors, providing cross-sectional images; showing how the radiopharmaceutical is taken up and used by the body.

    Nuclear Medicine:

    • Radioactive materials are introduced into the body.
    • Used to examine organ structure and function.
    • Radiation emitted detected by sensing devices; computed into images.

    Portable Radiography and Fluoroscopy:

    • Used when transporting a patient is not possible
    • Mobile units use battery power.
    • Provide diagnostic quality.
    • Used in surgical departments, ICU, OR, CCU, and other specialized areas.

    Sonography:

    • Uses high-frequency sound waves (non-ionizing radiation).
    • Probe sends sound waves, then echoes are received to produce images of body parts.
    • Evaluate blood flow (Doppler technique).

    Picture Archiving and Communication System (PACS):

    • Network allowing for combining digital imaging procedures (DR, CT, NM, UTZ, MRI).
    • Centralized management of patient images.
    • Images can be stored on optical disks, and transmitted via cables or satellites throughout the hospital or vicinity.

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