2016-12-12
1
LaserSafety
MD6305Laser‐TissueInteractions‐Class12
JaeGwan Kim
[email protected] ,X2220
DepartmentofBioMedical Scienceand Engineering
Gwangju InstituteofSciencesandTechnology
Copyright.Mostfigures/tables/textsinthislecturearefromthetextbook“Laser‐TissueInteractionsbyMarkolf H.Niemz 2007”andthismaterialisonlyforthosewhotakethisclassandcannotbedistributedtoanyonewithoutthepermissionfromthelecturer.
PPT modified from Jay Young Bae’s presentation
Index. Contents
1. Introduction.2. Laserhazards.
– Chemical/Electrical/othersecondaryhazards.– Eyehazards.– Skinhazards.
3. LasersafetystandardsandHazardclassification.– LaserHazardsClasses.– Classificationsystem.– Eyeprotection.
2016-12-12
2
Introduction.
Endotracheal tube set on fire by a CO2 laser
Introduction
Introduction. Introduction
2016-12-12
3
Introduction. Introduction
Papillomatous lesion : benign epithelial tumor growing exophytically(outwardly projecting) in nipple‐like and often finger‐like fronds
Introduction. Introduction
2016-12-12
4
Introduction. Introduction
• Specializedlaser‐resistantprotectedendotrachealtube
Introduction. Introduction
2016-12-12
5
Introduction. Introduction
Laser hazards – Chemical / Electrical / Other secondary.
‐ Rhodamine 6G is also used as a laser dye, or gain medium, in dye lasers, and is pumped by the 2nd (532 nm) harmonic from an Nd:YAG laser or nitrogen laser.
‐ Rhodamine 6G chloride is a bronze/red powder with the chemical formula C27H29ClN2O3. Although highly soluble, this formulation is very corrosive to all metals except stainless steel.
‐ Cryogenic coolant hazards. (Nitrogen gas)‐ Excessive noise from very high energy lasers.‐ X radiation from faulty high voltage (>15KV) power supplies.‐ Explosions from faulty optical pumps and lamps.‐ Fire hazards
Laserhazards
• Chemical/Electrical/Othersecondary
2016-12-12
6
Laser hazards – Chemical / Electrical / Other secondary.
Laser on amalgam can cause mercury fume.
Laserhazards
Laser surgery on viral disease :
Carbon dioxide laser energy is absorbed by intracellular water but not by proteins or nucleic acids. HPV DNA may be released during laser vaporization of genital HPV infected region.
HPV DNA type 6 was found in pre‐filter canister after laser treatment. Without appropriate equipment, surgeon can be contaminated by viral RNA and DNA.
HPV: human papillomavirus. Most HPV infections cause no symptoms and resolve spontaneously. In some, they persist and result in warts or precancerous lesions. The precancerous lesions increase the risk of cancer of the cervix, vulva, vagina, penis, anus, mouth, or throat.
Laserhazards
2016-12-12
7
Miscellaneous. Miscellaneous
• AbravesurgeonconductedLMSsurgery(laryngealmicrosurgeryusinglaser)onAIDSpatientwithjustonesuctiontipandsimplesurgicalmask.
• WhenwegetfirstHOLEP(HolmiumLaserEnucleationoftheProstate)machine,itspowerconsumeexceededtheoperationroom’spowersupply.Consequently,theoperationroom’spowersupplyshutdownedandallelectricfacilitysuddenlystoppedincludingpatient’sventilatorandallmonitoringdevices
• Surgeonusuallyusesalcoholtosterilizethelesionandadjacentskin.Liversurgerywasstarted,buttheArgonlaserdevicedidn’tworked.Sosurgeondrewbackthedeviceandchecked,thenputitonthedrapedskin,waitingforserviceengineer.Thensuddenlythedeviceemittedlaserbeambutnoonerecognizedatthatmoment.Soonafter,firebrokeoutonalcohol‐wetdrape.
Power&Hazards
• Power&Hazards– Nospecificthresholdbetweensafe,potentiallyhazardous,clearlydangerousbeam.
– Factors:Beampower,Exposuretime,Distancefromthelaser,retinalinjurylocation.
2016-12-12
8
EyeHazards
• EyeHazard– Deliberatelystare:1mWbeamcouldcauseaspotontheretina
– Considering“Aversionresponse(blinking)”:5mWbeamistolerable
– Above10mW:Blinkingisnotenough.thepotentialhazardfromgeneraluse
– Around100mW:Causeachangetotheretinawhichcanbedefinedasaneyeinjury
Eye hazards. EyeHazards
• Effectsofdifferentwavelengthsontheeye
2016-12-12
9
Eye hazards.
Ultraviolet Light
EyeHazards
Infrared Light
• Visible(400nm– 780nm)andnearinfrared(780nm– 1400nm)
Eye hazards.
Visible : Blink reflex (up to 1mW) NIR : No natural protection
EyeHazards
2016-12-12
11
• Cataracts
Eye hazards. EyeHazards
• Photokeratitis (“welder’sflash”or“snowblindness”)
‐ Sunburnofthecornea
‐ Usuallycannotnoticeuntilseveralhoursafterexposure
‐ Symptoms:Tear,pain,likehavingsandintheeyes
Eye hazards. EyeHazards
2016-12-12
12
Skin Hazards. SkinHazards
• Skinisthelargestorganofthebodyand,assuch,isatthegreatestriskforcomingincontactwiththelaserbeam.(hands,head,orarms)
• Lasereffectsontissuedependonthepowerdensityoftheincidentbeam,absorptionoftissuesattheincidentwavelength,timethatbeamisheldontissue,andtheeffectsofbloodcirculationandheatconductionintheeffectedarea.
• Around150mW:canbefeltontheskin.
• 500mW:beginstoburnskinifthepersoniswithinafewmetersofthebeam.
Skin Hazards. SkinHazards
• ImmediateEffects– Thermalinjury(temperatureelevation)– Photochemicaleffect:sunburn(excessivelevelofUVradiation)
2016-12-12
13
Skin Hazards.
Only UV has been shown to cause it
Accelerated Skin aging Skin cancer
SkinHazards
• Long‐termdelayedeffects
Skin Hazards.
Wavelength (nm) Possible effects
230~380 (UV‐C, ‐B, ‐A)
Erythema, skin cancer, accelerated skin aging
280~480 (UV‐B,‐A, Visible)
Increased pigmentation
310~400 (UV‐A) Photosensitive reactions
400~600 (Visible) Photosensitive reactions
700~1000 (Infrared) Skin burns, excessive dry skin
Infrared light
‐ Thermal damage (Skin burn)
UV light
‐ Photochemical reactions
(Change in the pigmentation, erythema, skin ca.)
SkinHazards
2016-12-12
14
BasicBiologicalEffectsofLight
백내장
홍반각막염
LASER safety standards & Hazard classification.
Laser Hazards Classes
‐ Classes are defined by their ability to produce damage in exposed people.
‐ Lasers are classified based on the concept of AEL (Accessible Emission Limits).
AEL (Accessible Emission Limit) = MPE x Area of LA
‐Maximum power or energy that can be emitted in a specified wavelength range
and exposure time that passes through a specified aperture stop at a specified
distance.
‐Mathematical Product of MPE and an area factor Limiting Aperture (LA)
‐ Limiting Aperture : Depends on factors such as laser wavelength and physical
factors like the fully dilated pupil size (7mm) and beam hotspots(1mm)‐ Hotspot : The brightest, central area in the beam
LaserSafetyStandards
2016-12-12
15
LASER safety standards & Hazard classification.
MPE (Maximum Permissible Exposure)
‐ The highest power or energy density of a light source that is considered safe.
‐ The MPE is measured at the cornea of the human eye or at the skin, for a given wavelength and
exposure time. (Usually about 10% of the dose that has a 50% chance of creating damage.)
LaserSafetyStandards
LASER safety standards & Hazard classification.
Classification systems
Hazardclassification
2016-12-12
16
LASER safety standards & Hazard classification.
ANSI Z136.1
Hazardclassification
LASER safety standards & Hazard classification.
ANSI Z136.1
Hazardclassification
2016-12-12
17
LASER safety standards & Hazard classification.
FDA/CDRH & IEC 60825
Hazardclassification
LASER safety standards & Hazard classification.
FDA/CDRH & IEC 60825
Hazardclassification
2016-12-12
18
LASER safety standards & Hazard classification.
Eye Protection
Optical density – how much incoming light is absorbed by a lens
→ H0: the anticipated worst case exposure
Ex) Nd:YAG laser, wavelength : 1064nm, output : 80mJ,
MPE : 5*10‐6 J/cm2, limiting aperture : 7mm
LaserProtection
LASER safety standards & Hazard classification.
Eye Protection
LaserProtection