lasers & lights by beverly nelson. outline of presentation defining laser production of laser...
TRANSCRIPT
Outline of Presentation
• Defining LASER• Production of laser• Classification of Laser• Method of application• Biological effects• Clinical indications• Precautions & contraindications
What is LASER ?
• Acronym for Light Amplification of Stimulated Emissions of Radiation
• Relatively new modality which is still undergoing research
Physics of LASER production
• Please read handout provided
• Laser light contains electromagnetic energy
Classification of Lasers
• According to the nature of material placed between the two reflecting surfaces
• Many types of lasers, each with specific wavelength and characteristics
Classification cont’d
• Classification according to high or low power
• Depends on the intensity of energy they deliver
Classification cont’d
• High power lasers or Hot Lasers generate thermal response
• Used in the Medical Realms- surgical cutting
Low level power laser
• Used as a rehabilitation intervention for pain management and wound healing.
• Is relatively new area in medicine (20 – 25 yrs)
• Maximal output of power < 1 milliWatt
Laser light used in Rehab
• There are two types of Laser lights used in rehabilitation
• Helium Neon –HeNe
• Gallium Arsenide -- GaAs
Helium Neon
• Gas laser• Uses a mixture of Helium and Neon in a
pressurised tube
• Creates Laser in the Red portion of the electromagnetic spectrum
Has a wavelength of 632.8nm
Depth of penetration
• Absorbed in the superficial tissues - 2- 5 mm of soft tissue
• Indirect effect at 8 – 10 mm depth of soft tissue
Laser output is affected by
• Care of the equipment
• The number of operating hours
• Quality of fibreoptics used
Gallium Arsenide Laser
• Utilise a diode to produce an infrared ( invisible) Laser
• Wavelength of 904nm 3 – longer wavelength than HeNe
• Absorbed at depths of 1 – 2 cm• Indirect effect of up to 5cm
GaAs Laser
• Has a peak power of 2watts which is delivered in a pulsed mode to decrease the thermal effect
• Greater potential for treatment of deeper soft tissue
Biological effects
• Promotes ATP production• Promotes collagen production• Modulates inflammation• Inhibits bacterial growth• Promotes vasodilatation- microcirculation• Alters nerve conduction velocity
Effects of Laser
• Facilitate wound healing • Reduction of pain• Increase tensile strength of star• Decrease in inflammation• Bone response
Clinical indication
• Tissue healing :chronic and acute wounds( can promote tissue repair but more high quality studies needed) accelerated healing
• Arthritis
• Postmasectomy Lymphedema (more evidence needed)
Clinical indication cont’d
• May reduce pain in patients with neuromusculoskeletal conditions .
• Eg back pain, neck pain, trigger points
• Pain management
Contraindications
• Direct irradiation of the eyes
• Malignancy
• Ares recently exposed to radiotherapy
• Haemorrhaging Regions
Precautions
• Low back or abdomen during pregnancy
• Epiphyseal plates in children
• Impaired sensation or mentation
Type of Diode• LED – light emitting diode- semiconductor diode
that produces low power light in a range of frequencies
• SLD- supraluminous diode- semiconductor that produces high power light in a narrow frequency range
• Laser diode – semiconductor diode and optics that produce laser light
Wavelength
• Laser light applicators produce/output light in the visible or near visible wavelength range of the electromagnetic spectrum
• IR (700 – 1100nm)- longer wavelength and penetrates deeper tissue up to 30 to 40 mm
• Red light(600 -900nm)- short wavelength and suitable for treating superficial tissue at a depth of 5- 10mm
Power
• Light applicator is measured in milliwatts
• Laser for therapy are power more than 5mW and less than 500mW
• Low power light applicators require more time to deliver the same amount of energy as high power light applicators
Energy Density
• Lower energy density recommended for acute and superficial conditions
• High energy density recommended for chronic and deeper conditions
Documentation
• Type of Diode- LD, LED,LED ?• Wavelength (nm)• Power (mV)• Area of body to be treated• Energy Density