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Questions and Answers
What is a common application of microwaves in medicine?
What is a common application of microwaves in medicine?
Which radiation is primarily used to kill rapidly-dividing cancer cells?
Which radiation is primarily used to kill rapidly-dividing cancer cells?
What is the wavelength range for X-rays?
What is the wavelength range for X-rays?
What is the role of a medical physicist in radiotherapy?
What is the role of a medical physicist in radiotherapy?
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How are gamma rays generated in space?
How are gamma rays generated in space?
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Which of the following is NOT a typical application of radio waves in medicine?
Which of the following is NOT a typical application of radio waves in medicine?
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What technology is used to generate X-rays in radiotherapy?
What technology is used to generate X-rays in radiotherapy?
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What are the characteristics of radio waves in terms of frequency and wavelength?
What are the characteristics of radio waves in terms of frequency and wavelength?
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What is the primary use of infrared (IR) imaging in a medical context?
What is the primary use of infrared (IR) imaging in a medical context?
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Which frequency range corresponds with infrared radiation?
Which frequency range corresponds with infrared radiation?
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What effect does ultraviolet (UV) radiation have on the human skin?
What effect does ultraviolet (UV) radiation have on the human skin?
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Which medical condition is treated using ultraviolet (UV) radiation?
Which medical condition is treated using ultraviolet (UV) radiation?
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Near infrared spectroscopy (NIRS) is mainly used for what purpose?
Near infrared spectroscopy (NIRS) is mainly used for what purpose?
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What is the primary wavelength range for Ultraviolet (UV) radiation?
What is the primary wavelength range for Ultraviolet (UV) radiation?
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Which device utilizes spectrophotometry to measure hemoglobin saturation?
Which device utilizes spectrophotometry to measure hemoglobin saturation?
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What is the wavelength range of microwaves within the electromagnetic spectrum?
What is the wavelength range of microwaves within the electromagnetic spectrum?
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Which of the following electromagnetic spectrum types has the shortest wavelength?
Which of the following electromagnetic spectrum types has the shortest wavelength?
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What is the wavelength range of visible light?
What is the wavelength range of visible light?
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Which color of visible light has the highest frequency?
Which color of visible light has the highest frequency?
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Which application utilizes visible light to treat jaundice in babies?
Which application utilizes visible light to treat jaundice in babies?
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What type of therapy combines light energy and photosensitizing medications?
What type of therapy combines light energy and photosensitizing medications?
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What is the purpose of a scanning laser ophthalmoscope?
What is the purpose of a scanning laser ophthalmoscope?
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What is the frequency range of visible light?
What is the frequency range of visible light?
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Which device is passed into the body to look inside through a natural opening?
Which device is passed into the body to look inside through a natural opening?
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What is primarily responsible for the production of electromagnetic waves?
What is primarily responsible for the production of electromagnetic waves?
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What is the relationship between electric and magnetic fields in electromagnetic waves?
What is the relationship between electric and magnetic fields in electromagnetic waves?
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What can be concluded about the speed of electromagnetic waves in a vacuum?
What can be concluded about the speed of electromagnetic waves in a vacuum?
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Which statement is true regarding the electromagnetic spectrum?
Which statement is true regarding the electromagnetic spectrum?
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In which conditions can electromagnetic waves travel?
In which conditions can electromagnetic waves travel?
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What is the connection between frequency and the properties of electromagnetic waves?
What is the connection between frequency and the properties of electromagnetic waves?
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What role does the electromagnetic spectrum play in understanding electromagnetic waves?
What role does the electromagnetic spectrum play in understanding electromagnetic waves?
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Which of the following correctly describes electromagnetic waves?
Which of the following correctly describes electromagnetic waves?
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Study Notes
Electromagnetic Waves
- Electromagnetic (EM) waves are produced by accelerating charges.
- EM waves are also called electromagnetic radiation.
- EM waves consist of oscillating electric and magnetic fields that travel away from the accelerating charges.
- A changing magnetic field induces a changing electric field, and vice-versa.
- These changing fields form electromagnetic waves.
- EM waves can travel through vacuum, air and solid materials.
- EM waves in vacuum or in air travel at a speed of 3.00 × 108 m/s.
Learning Objectives
- Lecture 1: Explain the electromagnetic spectrum, explain the properties of electromagnetic waves, and explain the medical uses of electromagnetic waves.
- Lecture 2: Explain what MRI is and how it works, explain the safety of using MRI, and explain the people who are not able to use MRI.
Introduction
- EM waves are produced only by accelerating charges.
- EM waves consist of oscillating electric and magnetic fields.
- A changing magnetic field produces a changing electric field, and vice versa.
- There are no electric waves or magnetic waves only electromagnetic waves.
- EM waves can travel through vacuum, air, and solid materials.
The Electromagnetic Spectrum
- EM waves exist at every frequency.
- The properties of EM waves and their interactions with matter depend on the frequency of the wave.
- The electromagnetic spectrum is traditionally divided into six or seven regions based on frequency and wavelength.
Visible Light
- Visible light is the part of the spectrum that can be detected by the human eye.
- For an average range, the frequencies of visible light are 430 THz to 750 THz, corresponding to wavelengths in vacuum of about 700-400 nm.
- White light can be separated by a prism into the colours red, orange, yellow, green, blue, and violet.
- Red has the lowest frequency (longest wavelength), and violet has the highest frequency (shortest wavelength).
- Lightbulbs, fire, the sun, and fireflies are sources of visible light.
- We see objects by the light they reflect.
Medical Applications of Visible Light
- Blue light treatment of jaundice in babies.
- Scanning laser ophthalmoscope (for examining the retina and optic nerve head).
- Photodynamic therapy (PDT) uses light energy and photosensitizing medications to treat certain types of cancer.
Endoscopy
- Endoscopy is a test to look inside the body using a long, thin tube with a small camera (endoscope).
- The endoscope is passed into the body through a natural opening such as the mouth.
- New approaches involve virtual endoscopy, using a high-resolution CT scan and a computer to show the internal organs as if viewed through an endoscope.
Infrared (IR)
- Infrared radiation (IR) is lower in frequency than visible light.
- IR extends from the low-frequency (red) edge of the visible spectrum to a frequency of about 300 GHz (λ ≈ 1 mm).
- IR waves are longer than visible light waves, but shorter than radio waves.
- IR is invisible to the human eye, but some animals can detect it.
- Thermal radiation given off by warm objects is primarily IR.
- IR is used in modern thermometers and thermography.
Medical Application of IR – Thermography
- Thermography uses infrared imaging to assess skin temperature.
- Assessing skin temperature is often used as an extension of a standard physical exam (especially for diagnosis and treatment plans).
Pulse Oximetry
- Pulse oximetry uses spectrophotometry to determine the proportion of hemoglobin that is saturated with oxygen.
Near Infrared Spectroscopy (NIRS)
- NIRS is a tool to assess oxygenation and hemodynamics in various organs like muscle and brain.
Ultraviolet (UV)
- UV radiation is higher in frequency than visible light.
- UV ranges in wavelength from about 10 nm to approximately 400 nm.
- UV is present in sunlight.
- UV exposure can lead to vitamin D production in moderate amounts, but excessive exposure can cause tanning, sunburn, and skin cancer.
- UV radiation can cause cataracts in the eyes.
- UV is used medically to treat certain skin conditions, for example psoriasis, vitiligo, and skin tumors of cutaneous T-cell lymphoma.
Microwaves
- Microwaves are part of the EM spectrum between radio waves and infrared.
- Microwaves are used in communication (cell phones, computer networks, satellite TV).
- Microwaves are used in radar.
- Microwave thermotherapy is used in cancer treatment.
X-rays and Gamma Rays
- X-rays and gamma rays have very short wavelengths and high frequencies.
- X-rays and gamma rays are used to produce images of the body's internal structures.
- X-rays are used to create images of bone, lungs, and other organs of the body and gamma rays are used for nuclear medicine.
- In conventional X-ray imaging, film records the amount of radiation that passes through tissue based on the density of the tissue.
- Computed tomography (CT) allows for cross-sectional images of the body structures.
Radiotherapy
- X-rays and other radiation damage DNA in rapidly dividing cells, this is why radiation therapy can be useful for killing cancer cells.
- Linear accelerators generate x-rays that rotate around the body to target radiation at the tumour, while minimizing damage to surrounding healthy tissues.
Radio Waves
- Radio waves are the lowest frequency and longest wavelength EM waves in the spectrum.
- Radio waves are extensively used for communication
- Common applications of radio waves in medicine are MRI (diagnostic imaging), RF ablation, and localized dielectric heating (shortwave diathermy).
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Description
This quiz covers the fundamentals of electromagnetic waves, including their production by accelerating charges and their propagation through various media. You'll learn about the electromagnetic spectrum, properties of EM waves, and their medical applications, particularly in MRI technology.
