Lasers in Veterinary Practice. Safe Use Guidelines

Transcription

1 Lasers in Veterinary Practice Safe Use Guidelines Prepared by: Radiation Protection, Environmental Health Services BC Centre for Disease Control March 2013

2 Introduction Veterinary laser safety issues are similar to human surgical medicine safety issues Education for Safe Use is Essential!

3 Introduction A brief inadvertent exposure to high power laser radiation can cause permanent eye injury&/or skin burns!

4 Introduction Safe use guidelines give the Designated Member (DM) & operating staff essential information for laser safety!

5 Introduction The DM is responsible to the CVBC for the management & practice of veterinary medicine & their obligation to take additional measures necessary to prevent health hazards from occurring in the veterinary facility.

6 Introduction Use of lasers is subject to provincial legislation i.e. worker health & safety

7 Introduction States: Equipment producing ionizing or nonionizing radiation must be installed, operated & maintained in accordance with the applicable standard, as listed in the regulation. "A WorksafeBC inspector may visit a site & inspect for compliance with the Occupational Health & Safety Regulation.

8 Introduction The Workers Compensation Board is also referred to as WorkSafeBC or WSBC

9 Introduction CVBC Responsibility CVBC will not test & assess machines but monitor whether members: 1) had their machines maintained, 2) facility has proper standards for use, 3) procedures are in-place for all workers to comply with occupational health & safety regulations under WorkSafeBC.

10 Introduction Laser Safety Health Canada has regulations for design, construction & performance of laser scanner demonstration laser

11 Introduction Lasers fall into two categories ( 1) Lower power lasers e.g. school lasers, laser pointers, supermarket checkout lasers, etc.) Laser Safety

12 Introduction Laser Safety 2) Higher power lasers (e.g. surgical lasers, entertainment lasers, industrial lasers, skin therapy, removal of tattoos, hair, spider veins, spots, warts, moles, etc.)

13 Introduction Laser Safety Lasers are classified from lowest power to highest power Class 1, 2, 3a, 3b, & 4 Warning labels indicate the degree of hazard of the laser to humans during laser operation!

14 Introduction Laser Safety Laser applications in veterinary medicine include: declawing, surgery, dermatology, ophthalmology, upper respiratory tract, urinary and GI tracts, wound management, etc.

15 Introduction Laser Safety High laser emission levels i.e. Class 3b & 4 emit laser radiation hazardous to unprotected eyes & skin from the direct beam, reflected beam &/or scattered beam.

16 Introduction Laser Safety The direct beam may be a fire hazard when striking combustible materials. Safety features are part of laser devices & operator training specific to the laser class is essential for safe use!

17 Introduction Laser Safety Safe Use Guidelines general laser safety roles & responsibilities risks associated with lasers Safe Use Guidelines provides advice to reduce health risks to laser users & others.

18 Laser Safety Responsibility Overall safety associated with installation & use of lasers remains the responsibility of the DM Class 3b & 4 lasers require a Laser Safety Officer (LSO),... responsible for implementing a laser safety program

19 Laser Safety Responsibility The DM must ensure that the laser operator is aware of the requirements for safe use.

20 Laser Safety Responsibility This means: 1. Laser operators must be trained in laser safety & 2. knowledgeable of local regulations.

21 Laser Safety Responsibility 3. Periodic documented laser safety audits of facility & personnel safety features conducted 4. Deficiencies re: eyewear, barriers, area controls, warning signs, equipment safety features (interlocks, labels, etc.) are corrected!

22 Laser Safety Responsibility c) Laser safety audits must be available for CVBC or WorkSafeBC inspector

23 Lasers produce an intense beam of pulsed or continuous invisible infrared light for cutting sealing tissue &

24 "L A S E R" is an acronym for Light Amplification by Stimulated Emission of Radiation

25 Benefits of laser surgery: decreased bleeding smaller blood vessels sealed decreased pain in post operative recover destruction of bacteria

26 Common veterinary lasers: Carbon dioxide (10,600 nm) Nd:YAG (1064 nm) Ho:YAG (2100 nm) laser diode laser (810, 980 nm) KTP (532 nm) - pulsed visible Argon ( nm) - visible

27 Lasers are identified by their lasing chemical element(s) Laser wavelength is measured in meters (m) & abbreviated e.g. μ micro , n nano , etc.

28 Laser light is coherent: light waves maintain a fixed phase relationship Laser light is monochromatic: composed of only one wavelength & one frequency

29 Unless laser light is caused to diverge by optics it is non-divergent!

30 Laser light travels in parallel waves It is composed of one wavelength & one frequency Increasing laser energy decreases time needed for tissue vaporization

31 Tissue vaporization can be accomplished by: 1. Increasing beam power output in watts (W) 2. Decreasing beam diameter in watts per square centimeter (W/cm 2 )

32 3. For pulsed lasers increasing the energy per pulse measured in joules (J) Laser light focused onto tissues is absorbed, transformed, reflected &/or scattered.

33 Choose a laser wavelength so that most of the light energy is... absorbed &/or transformed

34 When absorbed or transformed within target tissue laser energy interactions are classified as Photothermal

35 Photothermal Heat energy conducted to tissues results in hyperthermia & collateral tissue damage. Carbon black char can act as a foreign substance creating an inflammatory response & impede wound healing.

36 Photochemical Laser light is absorbed & converted into chemical energy, resulting in tissue destruction.

37 Photochemical Photodynamic therapy (PDT) use a laser activated photosensitizer drug... administered intravenously, orally or topically... stimulates destruction of chemically-labeled tissue

38 Mechanical-Photodisruptive Pulsed laser light can be converted into acoustical energy upon impact creating a shock wave that disrupts the target tissue (e.g. laser intracorporeal shock wave lithotripsy)

39 Laser energy applied to target tissue may be scattered forward in & through tissue causing heating & necrosis.

40 Backscatter can occur from partial reflections on impact with tissue... May have a damaging effect on staff & equipment if adequate safety precautions are not taken.

41 Nd:YAG & Argon laser are known to produce backscatter - can be helpful in cauterizing bleeders below the tissue surface. Nd:YAG laser penetrates 4-5 mm with large amounts of forward & backscatter... making it good for cauterization.

42 Visible Argon laser is highly absorbed by hemoglobin has a 2-3 mm penetration moderate forward & backscatter

43 Carbon dioxide (CO 2 ) laser s infrared radiation is highly absorbed by water Rapidly absorbed within the first 0.1 to 0.3 mm of tissue. Makes a good cutter but poor cauterizer

44 The carbon dioxide (CO 2 ) laser is one of the most widely used lasers. Heat diffusion into tissue surrounding the target results in collateral tissue damage.

45 Lowering laser setting does not necessarily improve things...less power requires longer contact times to produce the desired effect......which results in increased heat diffusion into surrounding tissue.

46 Alternatively Superpulsing of laser energy can allow tissue recovery between micropulses,...which is shorter in duration than the time required for diffusion of heat through tissue...

47 ...this allows thermal energy time to escape primarily through vaporization... resulting in minimal collateral heat diffusion.