Medical Physics: Laser in Medicine

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Questions and Answers

What is the process by which an electron changes energy levels and emits a photon in a random direction?

Radiation emission

Laser amplification

Stimulated emission

Spontaneous emission (correct)

What is the primary function of the optical resonator in a laser system?

To reflect the laser beam back and forth through the active medium (correct)

To focus the laser beam onto a small spot

To convert the laser beam into a different wavelength

To pump energy into the active medium

What is the term for the property of laser light where all waves are in phase, both in time and space?

Coherence (correct)

Monochromaticity

Brightness

Collimation

Which type of laser is commonly used in laser surgery?

Ruby laser Signup and view all the answers

What is the term for the interaction between laser light and biological tissues?

Laser tissue interaction Signup and view all the answers

What is the primary advantage of using lasers in medicine?

Increased precision and accuracy Signup and view all the answers

What is the term for the measure of the amount of energy emitted by a laser per unit time?

Power Signup and view all the answers

Which of the following is a safety concern in medical applications of lasers?

All of the above Signup and view all the answers

What is the term for the classification of lasers based on their wavelength?

Infrared, visible, ultraviolet, or X-ray Signup and view all the answers

What is the term for the type of laser that emits a continuous beam of light?

Continuous wave laser Signup and view all the answers

What is the primary mechanism of high power lasers in medical applications?

Generating heat and destroying targeted tissue Signup and view all the answers

What is the typical effect of mid-power lasers, such as helium-neon laser, on tissue?

Superficial effect with penetration up to 1.5 mm Signup and view all the answers

What is the unit of measurement for power density of laser light?

Milliwatts per centimeter squared Signup and view all the answers

What is the primary mechanism of low-power lasers, such as soft laser, in medical applications?

Biostimulation and tissue healing Signup and view all the answers

What is the term for the amount of power per unit area of laser light?

Power density Signup and view all the answers

What is the primary mechanism of laser tissue interaction that results in no biological effect?

Reflection Signup and view all the answers

What is the typical wavelength of an argon laser?

488-514 nm Signup and view all the answers

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

Milli joules Signup and view all the answers

What is the primary application of mid-power lasers, such as I.R. laser, in medicine?

Physical therapy Signup and view all the answers

What is the term for the rate of energy flow of laser light?

Power Signup and view all the answers

What is the main difference in energy deposition between xenon arc treatment and laser treatment?

Xenon arc treatment deposits 20 to 50 times more energy than laser treatment Signup and view all the answers

What is the purpose of using local anesthesia during xenon arc treatment?

To reduce eye movement Signup and view all the answers

What determines the amount of laser energy needed for photocoagulation?

The spot size used Signup and view all the answers

What is the purpose of photocoagulation in ophthalmology?

To repair retinal tears or holes Signup and view all the answers

What is the Minimal Reactive Dose (MRD) of laser energy?

The minimum amount of energy that causes damage to the retina Signup and view all the answers

What is the typical exposure needed for photocoagulation?

10 to 50 times the MRD Signup and view all the answers

What is a medical application of lasers in dermatology?

Removing tattoos Signup and view all the answers

What is the advantage of using lasers in surgery?

It reduces bleeding Signup and view all the answers

How are lasers used in gastroscopy?

Through a combination with fiber optics Signup and view all the answers

What is a medical application of lasers in ophthalmology?

Treating diabetic retinopathy Signup and view all the answers

What is the primary purpose of laser energy in medicine?

To deliver energy to tissue Signup and view all the answers

What is the effect of laser energy on human tissue?

It causes a rapid rise in temperature Signup and view all the answers

Why are short wave lasers (400-600nm) preferred over long wave lasers (700nm) in medical applications?

Short wave lasers are better absorbed by tissue Signup and view all the answers

What is the minimum temperature required to cause tissue destruction?

100°C Signup and view all the answers

What is the primary application of lasers in ophthalmology?

Photocoagulation of the retina Signup and view all the answers

What was the primary disadvantage of xenon arc light source for photocoagulation?

The retinal spot size was much larger Signup and view all the answers

What is the duration of exposure to 70°C that tissue can withstand?

1 second Signup and view all the answers

What is the impact of laser energy on biological tissue?

It causes both biological and chemical reactions Signup and view all the answers

What is the primary advantage of laser technology in medicine?

It is more precise and controlled Signup and view all the answers

What is the medical application of laser technology in treating cancer?

It is used to treat certain types of cancer Signup and view all the answers

Study Notes

What is a Laser?

Light Amplification by Stimulated Emission of Radiation (LASER)
An electron transition from higher to lower energy state emits a photon
Emission process can be spontaneous or stimulated emission

Basic Components of a Laser

Active medium or laser medium
Energy source (pump or pump source)
Optical resonator consisting of a mirror or system of mirrors

Laser Properties

Coherence: all waves are in phase, both in time and in space
Monochromaticity: one wavelength and one color
Collimation: waves travel in parallel directions (non-divergent)
Brightness: high energy density

Types of Lasers

According to active material: solid-state, liquid, gas, excimer, or semiconductor lasers
According to wavelength: Infra-red (IR), Visible, Ultra-violet (UV), or X-ray Lasers
Pulse Laser: Ruby laser (λ=694 nm), Semiconductor laser, Glass laser
Continuous Wave (CW) Laser: Neon-helium laser (λ=632.8 nm), Argon laser (λ=488-514nm)

Classification of Lasers

High Power Lasers (Hot): e.g., Co₂ laser
Mid-Power Lasers (Cold): e.g., I.R. laser, Helium neon (He Ne) laser, Infrared (IR) laser
Low-Power Lasers (Soft Laser): e.g., used by dermatologists

Laser Power

Measured in watts (W) or milliwatts (mW)
Power density: measured in milliwatts per centimeter squared (mW/cm²)

Laser-Tissue Interaction

Reflection: beam is reflected from the tissue without affecting it
Scattering: laser light is scattered, attenuating the desired energy
Transmission: laser beam penetrates through the tissue without affecting it
Absorption: laser energy is absorbed by the tissue, causing biological and chemical reactions

Medical Applications of Lasers

Ophthalmology: photocoagulation of the retina, treating certain types of cancer
Dermatology: skin tumor therapy, tattoos removal
Surgery: used for precise cutting and sealing of blood vessels, reducing bleeding

Laser in Ophthalmology

Photocoagulation: heating blood vessels to coagulate and block them
Xenon arc light source: disadvantages include larger retinal spot size, greater energy deposition, and longer exposures
Minimum Reactive Dose (MRD): the minimum laser energy that causes observable damage to the retina

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Description

This quiz covers the basics of laser technology in medicine, including its properties, applications, and interactions with tissues. It's a part of Medical Physics course.