Upload
builiem
View
217
Download
2
Embed Size (px)
Citation preview
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Exposure Limits for Laser Radiation
ICNIRP Member
U.S. Army Medical Research Department (Recently retired!)
San Antonio, TX
Bruce E. Stuck, ICNIRPExposure Limits for Laser Radiation
Bruce E. Stuck
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Lasers in Our Environment• Home (compact disk players, laser printers)• School (laser pointers, teaching optics)• Supermarket (bar code scanners)• Hospital (photocoagulate, burn, cut, ablate, PDT)• Communications (fiber optics, free space)• Entertainment (concerts, amusement parks, hotels,
electronic games)• Industry (heat, weld, cut, align, measure, count)• Military (rangefinders, designators, illuminators,
training devices)• Security Systems • Research Laboratories
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Medical Applications of Laser Radiation• Used in most medical specialties to:
Heat, burn, cut, ablate, illuminate, stimulate• A few examples:
– Corneal refractive surgery • Photo refractive keratoplasty (PRK) • PRK LASIK (Laser in-situ keratomilieusis)
– Photocoagulation– Photodisruption (secondary cataract removal)– Photodynamic therapy (PDT)– Surgery - endoscope compatible– Biostimulation or biomodulation– Flourescence angiography– Imaging (SLO, Wavefront corrected retinal Imaging, OCT)– Alignment (MRI)– Doppler blood flow– Skin rejuvenation (fractional laser therapy)
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
WavelengthRange (nm)
Ultraviolet180-315
315-400
Visible400-700
WavelengthRange (um)
Near Infrared0.7-1.4
Infrared1.4-1000
Laser Type
ArF ExcimerKrCl ExcimerKrF ExcimerNd:YAG(quadrupled)ArgonXeCl Excimer
Helium CadmiumNitrogenXeF ExcimerArgonKrypton
Helium CadmiumArgonCopper VaporKryptonNd:YAG (doubled)Helium Neon(HeNe)Dye (Coumarin)Dye (Rhodamine)HeNe (yellow)HeNe (orange)
HeNe (red)
Wavelength(s)(nm)
193222248266275308
325337351
351, 363350.7, 356.4
441.6476, 488, 514.5
511, 568530532543
400-550550-700
594610
632.8
Laser Type
InGaAlPKryptonRuby
Ti:SapphireGaAIAsAlexandriteGaAIASGaAsNd:GlassNd:YAG(HeNe)Nd:YAG
Erbium GlassHolmiumHydrogen FlourideErbium YLFDeuterium FlourideCarbon MonoxideCarbon DioxideWater VaporHydrogen cyanide
Wavelength(s)(um)
670nm647-676 nm
694.3 nm
0.7-1.00.78
0.72-0.800.850.9051.0601.064
1.080, 1.1561.318, 1.338, 1.356
1.542.06
2.6-3.02.94
3.8-4.05.0-5.5
10.6118337
Common Lasers and Laser WavelengthsCommon Lasers and Laser Wavelengths
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Laser Emission Characteristics• Emission Durations
– Single pulses as short as 10 femtoseconds (10-14 seconds)– Continuous wave (CW)– Repetitive pulses - Pulse repetition frequencies (single pulse
to 108 pps)• Emission Wavelengths
– Near ultraviolet to the far infrared– Usually highly monochromatic (single wavelength or color)
• Beam Divergence– Small beam divergence ( 0.1 - 1 milliradian)– 0.5 mr divergence - 50 cm beam diameter at 1 km– Retinal Hazard Region: retinal irradiance diameter can be 30
micrometers or slightly less– Most applications use a focused beam
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Update of Exposure LimitsLaser Radiation Issues
• dependence of the injury threshold on retinal irradiance diameter
• ns pulses • near infrared exposures (wavelength
dependence – new work near 1.3 m) • repetitive pulses
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Data Sources for Updates• Dose-response data (thresholds)
– Animal models– Cell models
• Interaction or injury mechanism assessment• Biophysical/computational models• Medical applications• Laser accident cases• Environment illumination
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Laser Laser BioeffectsBioeffectsDose Response RelationshipsDose Response Relationships
Dose ResponseWavelength OphthalmoscopyExposure Duration AngiographyRadiant Exposure PathologyIrradiance diameter Electrophysiology Exposure Site Visual FunctionRepetitive Pulse Imaging (OCT,SLO)
Exposure ( Hz – MHz) Cellular metrics (apoptosis)Repeated exposure genomics)
Time of Observation (hours, days, years?)
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Absorption• How effectively light is captured by a target tissue
Transmission• How effectively light penetrates overlying media to reach the target
tissue
Wavelength
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Measuring Retinal Injury Thresholds
ED50 – that dose having a 50% probability of producing an ophthalmoscopicallyobservable lesion at 1 – 48 hours after exposure. TIE – Total Intraocular Energy. That energy incident at the cornea of the eye within the area of the ocular pupil
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Threshold laserThreshold laser--induced retinal injury induced retinal injury occurs at the RPE due to the melanin occurs at the RPE due to the melanin absorptionabsorption
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Retinal ED50 Threshold Data and ELs for 0.7 to 1.4 mExposure Durations, 0.1 s and ns
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
0.7 0.8 0.9 1 1.1 1.2 1.3 1.4
wavelength, m
tota
l int
raoc
ular
ene
rgy,
J 0.1 s ED50, 1 hr
ns ED50, 1 hrns ED50, 24 hr0.1 s model fitns model fitns MPE0.1 s MPEproposed ns MPEproposed 0.1 s MPEnew proposed ns MPEnew proposed 0.1 s MPE
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Interaction/Damage Mechanisms
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Retinal Injury Thresholds
28
MPE2007
MPE - Proposed
1 10010
10-3
10-4
10-5
10-6
10-7
(mrad)
Spot-size Dependence
H (J
/cm
2 )
n-1/4
PS
D = 500 m
Coll. beam
1 10010
10-4
10-5
10-6
10-7
Number of Pulses
Repetitive Pulse
ED
50 (J
/pul
se)
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Summary• Updated Exposure Limits for Laser Radiation.
– Spot-size dependence (“time dependent max”)– Nanosecond exposure durations– Repetitive pulses– Near Infrared– Measurement acceptance angles more clearly defined
• Update had a long gestation period! Basis: Data acquired and reviewed in the last 3-10 years.
• Most of the Els have NOT changed. • Harmonization – Based upon ICNRIP Guidelines!
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Future Research/ Issues• Long duration exposures
– Advanced imaging devices• Repetitive pulses• Far Infrared - 10 m to 1 mm (THz region)
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Acknowledgements• Jack Lund• Brian Lund• Karl Schulmeister• Per Soderberg• David Sliney• Benjamin Rockwell• Robert Thomas• Jeremiah Brown, Jr.• Martin Mainster• Joseph A. Zuclich
Edinburgh, United Kingdom, 9-11 May 2012ICNIRP 7th International NIR Workshop
Bruce E. STuck, ICNIRP Exposure Limitts for Laser Radiation
Thank you!
Questions?