Transcript LASER
LASERS & Lights By Beverly Nelson 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 Properties of LASER • Coherence• Monochromaticity • Collimination 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 • • • • • Crystal Gas Glass Semiconductor or diode chemical 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 Low lever Laser • Work by producing photochemical rather than thermal effect 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 Method of application • There are three methods of application: • Gridding • Scanning • Wanding 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 Parameters for the use of lasers • Type of diode • Wavelength • Power • Energy density 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 Suggested readings • Physical Agents in Rehabilitation by Michelle Cameron • Therapeutic Modalities in Rehabilitation by William E.Prentice