Medical Physics Chapter 7: Light in Medicine
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Questions and Answers

What is the definition of light in the context of medicine?

  • Electromagnetic radiation with electric charge
  • A type of electromagnetic radiation with a specific wavelength
  • Electromagnetic radiation within the visible spectrum (correct)
  • A type of radiation with no specific wavelength

    • What happens when light travels from one material to another?

  • It speeds up
  • It bends, or is refracted (correct)
  • It stops
  • It changes direction

    • What is the ratio of the speed of light in a vacuum to its speed in a given material called?

  • Index of refraction (correct)
  • Speed of light index
  • Refraction index
  • Light speed constant

    • What is the form of light that can be absorbed by a single molecule?

    <p>Particle form</p> Signup and view all the answers

    What happens when a light photon is absorbed by a molecule?

    <p>All of the above</p> Signup and view all the answers

    What is the term for the bending of light as it passes from one material to another?

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

    What is the term for the energy change that occurs when light is absorbed?

    <p>Chemical energy</p> Signup and view all the answers

    In what three categories is light studied in medicine?

    <p>Visible, ultraviolet, and infrared</p> Signup and view all the answers

    What is the basis of the use of laser light in medicine?

    <p>Heat production</p> Signup and view all the answers

    What is the term for the property where a lower energy light photon is emitted after a photon is absorbed?

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

    What type of reflection occurs when rough surfaces scatter light in many directions?

    <p>Diffuse reflection</p> Signup and view all the answers

    What is the unit of measurement currently recommended for wavelengths of light?

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

    What is the range of wavelengths for ultraviolet light?

    <p>100 to 400 nm</p> Signup and view all the answers

    What is the application of fluorescence in the detection of porphyria?

    <p>To detect teeth fluorescence</p> Signup and view all the answers

    What is the purpose of specular reflection in medicine?

    <p>To create images in medical instruments</p> Signup and view all the answers

    What is the range of wavelengths for visible light?

    <p>400 to 700 nm</p> Signup and view all the answers

    What is the application of transillumination in infants?

    <p>Right frontal sinus catheterization</p> Signup and view all the answers

    What is the purpose of phototherapy in treating jaundice?

    <p>To lower the bilirubin levels in the blood</p> Signup and view all the answers

    What is the effect of ultraviolet light on germs?

    <p>It kills germs</p> Signup and view all the answers

    What type of light is used in a blacklight?

    <p>Ultraviolet-A light</p> Signup and view all the answers

    What is the primary benefit of ultraviolet light from the sun?

    <p>It produces vitamin D</p> Signup and view all the answers

    What is the definition of a premature infant?

    <p>A baby born before 37 weeks of gestation</p> Signup and view all the answers

    What is the process by which phototherapy treats jaundice?

    <p>Photo-oxidation</p> Signup and view all the answers

    What is the term for the type of lamp that emits long-wave ultraviolet light?

    <p>All of the above</p> Signup and view all the answers

    When was the first successful laser made?

    <p>1960</p> Signup and view all the answers

    What is unique about a laser beam?

    <p>It remains narrow over long distances</p> Signup and view all the answers

    What is the purpose of laser wavelength selection in medicine?

    <p>To ensure the wavelength is strongly absorbed by tissue</p> Signup and view all the answers

    What is the current use of lasers in ophthalmology?

    <p>Primarily for photocoagulation of the retina</p> Signup and view all the answers

    What is the primary purpose of a Wood's lamp?

    <p>To diagnose skin conditions</p> Signup and view all the answers

    What is the term for the process of heating a blood vessel to the point where the blood coagulates and blocks the vessel?

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

    What type of light is blocked by Wood's glass?

    <p>Most visible light</p> Signup and view all the answers

    What is the unit of measurement for the total energy of a typical laser pulse used in medicine?

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

    What is the wavelength of ultraviolet light used in a Wood's lamp?

    <p>365 nanometers</p> Signup and view all the answers

    What is the primary cause of skin cancer in humans?

    <p>Ultraviolet light from the sun</p> Signup and view all the answers

    What is the duration of a typical laser pulse used in medicine?

    <p>Less than a microsecond</p> Signup and view all the answers

    What is the term for the use of long IR heat waves to measure body temperature?

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

    What is an area of research where lasers are being used?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of reflective IR photography?

    <p>To show the patterns of veins just below the skin</p> Signup and view all the answers

    What is the characteristic of laser light that makes it unique?

    <p>Each wave is in phase with the others near it</p> Signup and view all the answers

    What is the term for the process by which ultraviolet light affects the skin?

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

    Study Notes

    Light in Medicine

    • Light is a form of electromagnetic radiation with a specific portion of the electromagnetic spectrum.
    • Light has no electric charge and travels at a constant speed.

    Properties of Light

    • Light changes speed when passing from one material to another, causing refraction.
    • Light behaves as both a wave and a particle, exhibiting properties like interference, diffraction, and absorption.
    • When light is absorbed, its energy is converted into heat, which is used in medical applications like tissue heating and laser welding.
    • Fluorescence occurs when absorbed light is re-emitted at a lower energy level, used in medical applications like detecting porphyria and in fluorescent microscopes.

    Measurement of Light and Its Units

    • Light is categorized into three types: ultraviolet (UV), visible, and infrared (IR), based on their wavelengths.
    • The recommended unit of measurement for light is the nanometer (nm), with UV ranging from 100 to 400 nm, visible light from 400 to 700 nm, and IR above 700 nm.

    Applications of Visible Light in Medicine

    • Visible light is used in phototherapy to treat jaundice in newborns, reducing bilirubin levels through photo-oxidation.
    • Transillumination is used to diagnose conditions like hydrocephalus, pneumothorax, and sinusitis.

    Applications of Ultraviolet and Infrared Light in Medicine

    • Ultraviolet light has germicidal properties, used to sterilize medical instruments, and can also cause skin reactions, including the production of vitamin D.
    • Wood's lamp is a diagnostic tool used in dermatology to analyze skin conditions using UV light.
    • Infrared light is used in thermography to measure body temperature and in reflective IR photography to show vein patterns and pupil size.

    Hazards of Light

    • Ultraviolet light from the sun can cause sunburn, tanning, and skin cancer, especially for people who spend a lot of time outdoors.

    Lasers in Medicine

    • A laser is a unique light source that emits a narrow beam of monochromatic, coherent light.
    • Laser light can be focused to a very small area, resulting in high power density and is used in medicine for various applications, including ophthalmology.
    • Laser pumping methods include continuous wave (CW) and pulsed wave (PW).
    • Lasers are used in ophthalmology for photocoagulation of the retina and are being investigated for treating cancer and as a "bloodless knife" for surgery.

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    Description

    This quiz covers the basics of light and its applications in medicine, including measurement, visible light, ultraviolet and infrared light, and laser technology. Learn about the properties of light and its uses in medical fields.

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