LASERS : ASPECTS OF EFFECTIVENESS AND SAFETY* * * C P Malherbe SUMMARY The use of laser therapy by physiotherapists has shown a marked increase in popularity over recent years. Effective­ ness and safety of lasers is essential. The results of an investigation by the CSIR of some infrared lasers is reported, highlighting, e.g., that all that SAYS laser m ay not BE laser. New legislation that will ensure that lasers conform with the minimum requirements to be safe and effective products, is discussed. The risk of laser radiation and product/premises licenses as a means of ensuring safe use of lasers, are explained. O PSOMM ING Die gebruik van laserterapie deur fisioterapeute het oor die laaste paar jaar baie toegeneem . Effektiwiteit en veiligheid van lasers is noodsaaklik. Die resultate van 'n ondersoek wat deur die W NNR op enkele infrarooi lasers gedoen is, en aandui dat nie alles wat laser SE dit noodwendig IS nie, word bespreek. Nuwe wetgewing w at sal verseker d at lasers aan die minim um vereistes voldoen om veilige, effektiewe produkte te wees, word bespreek. Die gevare van laserbestraling en produk/perseel- lisensies as 'n manier om veilige gebruik van lasers te verseker, word verduidelik. INTRODUCTION L a s e r t h e r a p y is f a s t b e c o m i n g a p o p u l a r m o d a l i t y in physiotherapy. T his form o f phototherapy has been gaining ground in proportion to the increased m arketing o f various lasers in South A frica over the last couple of years. Safety and effectiveness is of great im portance in perform ing o u r professional service. W hen a new treatm ent modality is in tro ­ duced, ensuring effectiveness and safety may however be difficult, for two main reasons. Firstly, control over the electronic equipm ent/products a ccord­ ing to set standards of safety and reliability initially may not exist. Such control may only be instituted a fte r som e time and could possibly take years. Secondly, lack of relevant inform ation, training, understanding of the uses, potential dangers, m ethod of application, and estim ating the p ro p e r dosage is a problem . Ft is not uncom m on for physiother­ apists in private practice and hospitals to start using a new modality when the only inform ation available is from m anufacturer's b ro ­ chures, manuals, etc. It usually takes som e tim e for workshops to be held on the subject fo r qualified physiotherapist. It may also take som e tim e for the subject to be included in the undergraduate curriculum . Scientific research may often be very sparse, even n on­ existent. This is certainly the case for laser therapy. T his p aper deals with the effectiveness and safety of laser equipm ent and th eir safe use. T he results o f an investigation of some infrared lasers as well as regulatory control of laser products and its im plications fo r South A frican physiotherapists a re discussed. DEFINITION A laser is a device which em its optical radiation (radiation in the ultraviolet, visible and infrared regions o f the electrom agnetic spectrum ) with unique characteristics due to the process o f Light Am plification by the Stim ulated Em ission of R adiation (for which L A S E R is an acronym )1. Such radiation is typically m onochrom atic (o f a single wavelength o r lying within a very narrow wavelength b and), o f high energy and power density, c oherent (all waves bein^ in phase) a nd unidirectional (parallel; having minimal divergence)1' - . MEDICAL USE OF LASERS In m edicine lasers a re e ith e r used for bringing a bout definite 2 therm al changes a n d /o r destruction o f tissues , o r for its biostim ula- 3 4 5 tory effects ’ ’ . High pow er (hot) lasers a re used in various medical a pplica­ tions, including surgery, ophthalm ology a nd derm atology. T he c a rb ­ on dioxide (C O 2 ) laser (wavelength 10,6 f m ) is used fo r surgical cutting and coagulation. T he argon laser (wavelength 488/514 nm ) is used in ophthalm ic surgery for “welding” detached retinas. T he n e o d y m i u m - y tt r i u m - a lu m i n iu m - g a r n e t ( N D - Y A G ) la s e r ( w a v e ­ length 1064 nm ) is used for arresting haem orrhage and destroying 2.3 5tum ours . Biostim ulation is achieved by laser trea tm e n t with a d ose rate that causes no im m ediate d e tectable tem p e ra tu re rise in treated tissue and no m acroscopically visible change in tissue stru c tu re . This is term ed “low level laser therapy” (L L L T ) by O hshiro and C alde- rhead 7. O th e r term s used in connection with biostim ulation are cold/soft/m id laser. LASER SOURCES: LASER WAVELENGTHS M o s t c o m m e rc ia l in s tr u m e n ts u se a la s e r s o u r c e w h ic h is w ither a small helium -neon (H e-N e) (gas) laser with a continuous wave (cw) power, o r a diode laser which may be cw o r pulsed ’ . A H e-N e laser produces optical radiation at a wavelength of 632.8 nm (visible red light)5, whereas the com bination of elem ents that m ake up a sem iconductor laser diode determ ines the wave- 2.5le n g th o f th e r a d ia tio n w hich is p ro d u c e d . G a lliu m A rs e n id e (G aA s) and the gallium alum inium arsenide (GaAIAs) diodes are b o th c o m m o n ly u s e d a n d p r o d u c e invisible in fra re d ( I R ) light. W avelengths in the n e a r infrared region, e.g. 904 nm, is relatively com m on for physiotherapeutic use. T he ability o f the laser diode (depending on th eir com position) to em it at different wavelengths to g eth e r with th eir low cost (relative to the H e-H e tubes o f higher pow er ranges), small size and ro b u st­ ness has m ade this type of laser m edium very p o pular with the m anufacturers o f biomedical laser systems. It m ust however be noted that not all diodes a re m ade with the sam e optical properties o r the sam e m ethod of m anufacturing so a variation o f quality of beam radiance, divergence, wavelength bandw idth) is expected . It is im portant that m anufacturers provide a d equate radiation specifi­ cations of the laser product. CREDIBLE LASER T o re produce the clinical results th a t is re p o rte d in th e lit- * This article is published with permission of the CSIR (C ontract re p o rt C/D PT 95). ** C P M alherbe, BSc in Physiotherapy, Part-time lecturer, D ep artm en t of Physiotherapy, U niversity o f Stellenbosch. Bladsy24 Fisioterapie, Mei 1991, deel 47 no 2 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) e rature, it must be ensured that the characteristics o f the laser radiation is identical. F o r instance, a narrow bandw idth o f w ave­ lengths is supposed, together with the expected high intensity due to the process o f amplification. In the past it was assum ed that potentially hazardous electronic products, e.g. lasers, would be im ported almost exclusively from recognised m anufacturers that m aintain internationally accepted norm s for safety and effectivity. M ore recently, however, m ore and m ore products o f less well known and even unknown origin, includ­ ing locally m anufactured products, have ap p eared on the South African m arket, often not complying with the required stan d ard s8. CSIR INVESTIGATION Against this background, the Division o f Production T echnol­ ogy of the CSIR was comm issioned by the University o f Stellenbosch during 1989 to investigate by m eans o f radiom etric m easurem ents th e c h a ra c te ris tic s o f five n e a r in fra re d r a d ia tio n s o u rc e s ( la s e r diodes) used in physiotherapy (table 1.). The devices were c h a ra c ­ terised with regard to spectral properties, radiant pow er and beam divergence. MAKE MODEL SERIAL NO OPERATION CLASS Lasdac (2 probes) No Model No.No serial no. Continuous lllb Laserex LTU 904 2176 Pulsed I Mesolaser IR01 820709 Pulsed lllb LAWO AL607/4 8908745 Continuous Ilia Medical Electronics LSI2030 01655M Continuous l/lllb according to power TABLE 1: DETAILS OF EQUIPMENT INVESTIGATED Spectral properties O n the basis of the relatively broad band o f wavelengths (895 q 75 nm ) of one o f the two proves of the Lasdac, it was concluded that it was an ordinary light em itting diode (L E D ) (o r infrared em itting diode) as distinguished from a laser d iode9. T he advertise­ m ent o f this probe as a laser diode would be misleading. This indicates that q u ite a num ber o f physiotherapists wlio had bought Lasdac laser units during o r before 1989 were not/are not treating with true laser when using the 895 nm probe. Clinical effects c o u ld t h e r e f o r e n o t b e a s c rib e d to la s e r r a d ia tio n . R e p o r ts o f c o m ­ parative results using the two different probes may be of interest. It has also come to light that the peak wavelength of som e of the products (m esolaser, L asdac) differs from that which is stated by the m an u fa ctu re r1̂ ’1 '(ta b le 2). This may be o f im portance when reporting on clinical research, o r when com paring the effects of radiation o f different wavelengths. Radiant power T able 3 shows approxim ate average power m easured for each source in com parison to the m anufacturer’s specifications. T he m easured average power o f the M esolaser (a pulsed source) differs from that calculated by the form ula Pav = f x pw x Pp, w here Pav = average laser power in watts, f = pulse frequency in hertz, pw = pulse .width in seconds, Pp = peak power in w atts2, . This is apparently because the pulse width is actually less than 200 n s9,10. This would indicate that output m easurem ents a re vital when reporting research results. A n o th e r interesting observation is that m ost o f the radiation sources tested, excluding the LA W O , show ed a lack of power s ta ­ bility, especially just a fte r switch-on, when d rops in o u tp u t power in excess o f 10% were observed. In assessing the dosage this observa­ tion should be noted. Source Peak wavelength (nm) Measured spectral bandwidth A A(nm)1 Conditions4 Lasdac Probe 1 8 9 5 (v 880) 75 Set to square wave ("pulse” mode), and a frequency of 30/s (although found to be independent of frequency). Probe 2 820 6,5 Equipment appears to malfunction in continuous mode The power setting had no effect. Laserex 912,5 2,5 Set to “Hi", i.e. repetition frequency of 5000/s. Mesolaser 915 6 2 Set to a repetition frequency of 5000/s, and the "30W" peak 9163(v 904) power setting. 4,53 LAWO 783,5 2 Set to D (continuous mode). Set to 5m W power. Medical Electronics 786 1,5 This unit has no continuous mode, only “Polyfrequency". Alpha frequency disabled. A = Full width of half m axim um 1 - The m onochrom ator bandw idth was in m in all cases except fo r'p ro b e 1 of Lasdac, where it was 2nm Therefore the spectral bandw idth of the sources will be slightly less than the m easured values 2 = Soon after switch-on 3 = After 5 m inutes or more 4 = These cond itions apply for all subsequent m easurem ents except where otherwise indicated TABLE 2: SPECTRAL PROPERTIES OF DIFFERENT SOURCES Source Class Average total power Presumed total power lllb lllb I Ilia 8m W 4m W 1mW 1m W 1 20m W 2 5m W 30m W Lasdac Probe 1 Probe 2 *Laserex 'Mesolaser3 LAWO Medical Electronics l/lllb 4m W 4m W * Pulsed lasers: Peak power is in excess o f 1000 tim es average power, as the pulse width is less than 200ns4 with a repetition rate of 5000/s. 1 On the “ 1W" peak power setting. 2 On the "30W " peak power setting, after being on for several m inutes. 3 The lower power reading was obtained first, and actually exceeded im W . However, when switched from the "30W " setting dow n again to the “ 1W” setting, the value had droppe d to about half, but started slowly to rise again, in cluding therm al changes in the laser. 4 Norm ally just und er 200ns, for both the Laserex and Mesolaser, as checked w ith a fast detector. -However, pulses as short as 100ns were also on occasion observed with the Mesolaser, on the lo w power setting. TABLE 3: RADIANT POWER Beam divergence Beam divergence spread was tested and docum ented and is applicable fo r all probes. D ivergence and distance from the skin is of m uch im portance with regards to determ ining o r calculating dosage, e.g. for treatm en ts in contact versus trea tm e n t at 1 cm from the skin. At a distance of 1 cm, according to the inverse square law, the irradiance (pow er/cm 2) is one ten th o f the irradiance at a distance o f 0,3cm. LICENCING OF LASER PRODUCTS Prospective buyers of laser o r any o th e r e le ctrotherapy a p p a ra ­ tus should take n ote that regulatory control o f these p ro d u c ts in South Africa was instituted on 14 A pril 1989. U n d e r the H azardous Physiotherapy, May 1991, vo! 41 no 2 Page 25 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) Substances A ct (A ct IS o f 1973) , the list o f electronic products d eclared as G ro u p III hazardous substances (refe rred to as listed e lectronic products) was th en added to include, a p a rt from X -ray equipm ent, products o r equipm ent capable o f em itting ionising and non-ionising radiation, o r sonic, infrasonic o r ultrasonic waves13. Lasers, ultraviolet em itting devices, diatherm y units, infrared h eaters a n d m edical ultrasound devices th en becam e controllable u n d e r the A ct, requiring users o f these products to be licenced. A second set o f regulations was also published13, enabling c ontrol o f th e m anufac­ tu re rs a n d sellers o f electronic products. T hey now also need to be licenced. Since then th e D e partm ent o f N ational H ealth and Population D evelopm ent controls th e sale o f G ro u p III electronic products, by ensuring th at each m odel o f all m anufacturers o f a specific listed p roduct, including lasers, conform w ith c ertain minim um standards o f safety (prim arily), befo re a licence will be issued perm itting the m odel to be sold. Such p roduct licence will g u arantee th e safety and reliability of these expensive products to the end user. Any supplier o f a laser p roduct o r o th e r listed electronic pro d u cts is now expected to display a sticker o f th e D ept, o f N ational H e alth on th e product, indicating th at th e product has been licenced for the purposes o f sale. SAFE USE OF LASERS T h e control o f lasers u n d e r th e A c t10 is d u e to the potential h e alth hazards, and users a re required to a d h ere to safety p re c a u ­ tions. Mechanisms of injury, critical organs, contributing factors T h re e prim ary mechanism s o f injury exists fo r exposure to laser radiation, i.e. therm al, photochem ically induced a nd therm o-m ech- anical injury ’ . Since laser radiation is n ot very penetrating (1-2 mm fo r w avelength 630 nm, o r twice th at at 800-900 n m )6, the eye and skin a r e c ritic a l o r g a n s o f injury. T h e ty p e o f b io lo g ic al e ffe c t, in ju ry th resholds a nd dam age m echanism s on these organs vary significant­ ly with laser pow er and w avelength . G enerally th e effects o f laser ra diation a re n ot different from the effects o f optical radiation from a conventional source with the sam e wavelength range, exposure d u ra tio n and irradiance . L aser radiation however engenders c o n ­ c ern d u e to the special pro p erties associated with is radiation : the high intensity, o r energy in to o n e point - its concentration and directional “targeting” . T h e eye is o f special concern, since it is capable o f increasing th e light intensity many hundreds o f tim es due to its focusing properties. T he harm ful effects o f exposure to different spectral bands of ordinary light is well known to physiotherapists. T able 4 tabulates the adverse health effects o f laser radiation. 12 Risk according to class S om e idea o f the risk/hazard associated with laser ra d ia tio n can be derived from a laser’s allocation to o n e o f fo u r designated classi­ fications. T he level o f radiation to which hum an access is^possible a nd its associated hazard dete rm in e th e class o f th e p ro d u c t . Accessible em ission limits (A E L ) is dete rm in e d fo r each class. T h e A E L is th e maximum accessible em ission level perm itte d within a p a rtic u la r class com putable as a function o f em ission d u ra tio n and w avelength . E ach laser in class II-IV should have a yellow w arning sign and explanatory label, including th e laser class. T h e risk fo r each class o f laser is sum m arised in tab le 5. CLASS I Low power lasers. Not hazardous for the eye or skin intrinsically safe. Called “exempt" lasers. CLASS II Low power/low risk laser systems. Only hazardous if the viewer continuously stares into the source; safe for accidental momentary viewing due to reflex eye closure. CLASS III Moderate risk/medium power lasers. Can cause injury to parts of the eye; however not capable of causing serious skin injury. Safe after diffuse reflection. CLASS Ilia Lasers for which direct intrabeam viewing with optical aids m ay be hazardous, but for which the natural aversion response (eye clo­ sure) would normally protect the unaided eye. CLASS lllb Hazardous for retina on intrabeam viewing, depending on expo­ sure duration and distance; at greater distance and diffuse reflec­ tion no danger. CLASS IV High power lasers, high risk of injury. Can cause combustion of flam m able materials, eye hazards and skin injury even from dif­ fuse reflections. Unsafe. TABLE 5: RISK ACCORDING TO LASER CLASS1'4 Practical safety measures M ost lasers used in physiotherapy a re class l llb ( o r lower) lasers. E ven fo r contact o r n e a r c o ntact ( r lc m ) treatm en ts by m eans o f a p ro b e it is advisable th at th e ' p a tient and o p e ra to r w ear a p p ro ­ priate glasses1. In the case o f trea tm e n t n e a r the eye o r w hen using a laser which radiates from a distance, p ro tection o f th e eye is essential 4. Preferably no sp e c ta to rs should be allowed. ELECTRONIC PRODUCT/PREMISES LICENSES C ontrol o f th e use o f laser products (applicable to class lll b a nd class IV lasers) is exercised according to a requirem ent o f the licence fo r the purposes o f th e sale that th e u se r o f such p roducts m ust be in possession o f a valid p ro ­ duct/prem ises licence befo re he/she uses the p ro ­ d uct 3 In granting a prem ises licence th e following fa c to rs a r e ta k e n in to c o n s id e r a tio n : E n g in e e r in g controls - th e product; controls such as d o o r in te r­ locks, filtered viewing optics, etc. Personnel p ro te c ­ tion - p ro p e r personal protective equipm ent, e.g. suitable eyewear, clothing a nd gloves. Adm inistrative and procedural c o ntrols - 7 standard op eratin g p ro ­ cedures, ad eq u a te education and training o f ’ users, posting o f warning signs a nd labels, re g u la r m ain ten ­ ance a nd servicing o f th e equipm ent a nd designation o f a laser safety officer. Such prem ises/electronic license is a m eans of ensuring th at th e end u se r will comply with safety r e q u i r e m e n t s w h e n u s i n g t h e l a s e r o n h i s / h e r prem ises. Provision is m ade in th e R egulations fo r radiation c o ntrol officers to inspect facilities a nd p ro ­ cedures to e n su re safe use o f th e equipm ent . Bladsy26 Fisioterapie, Mei 1991, deel 47 no 2 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. ) A ll p h y s i o th e r a p is t s /h o s p ita l s /p r a c tic e s u sin g la s e r sh o u ld apply to the D e partm ent o f National H ealth for prem ises licenses. A premises licence is also required for lasers purchased p rio r to 14 April 1989. If you a re in possession o f a laser, please inform the D e p a rt­ m ent so that a register o f laser users can be compiled. Such a register will a id th e d e p a r t m e n t in d i s tr ib u tio n o f i n f o r m a tio n , in s p e c ­ tion/m onitoring, as well as the facilitation o f training/education. Address for applications A pplication should be m ade to the D ire cto rate of R adiation C ontrol, D e partm ent o f N ational H ealth and P opulation D evelop­ m ent, Private Bag X62, Bellville 7535. This D ire cto rate is available as a source o f inform ation and consultation. Acknowledgements G rateful appreciation is recorded to the personnel, D ire cto rate o f R adiation C ontrol, Bellville, fo r editing this paper. T hanks to M essrs I Olivier and L A C M onard from the CSIR for conducting the research on the different laser sources, and to the University o f Stellenbosch for the research grant. REFERENCES 1. C ode o f practice Non-ionising R adiation - Lasers. 1988. D ire cto rate of R adiation C ontrol, D ept o f N ational H ealth and Population D evelop­ ment, Private Bag X62, Bellville 7535. 2. Liggins C. Light Am plification by Stim ulated Emission o f R adiation. C ontents o f W orkshop on laser therapy 1988. D ept o f Physiotherapy, U niversity o f D urban-W estville, Private Bag Congella, D u rb a n 4013. 3. Lievens P. L asertherapie (deel 1). N e d TFysiotherapie 1986;96:135-139. 4. Koel G, M oolenaar H. D osering bij Lasertherapie. N e d T Fysiotherapie 1989;99:312-318. 5. W oolley-H art A. A H andbook fo r L o w Power Lasers a nd their M edical A pplication. London: East Asia Co., 1988. 6. King PR . Low-level laser therapy: A review. Physiotherapy Theory and Practice 1990;6:127-138. 7. O hshiro T, C alderhead RGXou> Level Laser Therapy: A Practical Intro­ duction. C h ic h e ste r Jo h n Wiley, 1988. 8. M edical lasers and the law. 1990. D ire cto rate o f R adiation C ontrol, D ept o f National H ealth and P opulation D evelopm ent, Private Bag X62, Bellville 7535. 9. Olivier I, M onard LAC. Investigation o f n ear infrared radiation sources. C SIR C ontract R e p o rt C /D P T 95. Novem ber 1989. C SIR, P O Box 395, P retoria 0001. 10. Manual: M esolaser IR 01, M edico Electronic, Belgium. M edical D is­ tributors (Pty) L td, P O Box 92, W oodstock 7915. 11. Inform ation on Lasdac laser unit, L T C CC. Brentwood M arketing, 9 th Floor, Suite 94/95, W estgard House, 63 G ardiner Street, D urb an 4001. 12. H azardous Substances Act (A ct 15 o f 1973). G overnm ent G a ze tte 4 April 1973; Vol 94, N o 3834. 13. H azardous Substances A ct - Schedule o f G roup III H azardous S ubstan­ ces and R egulations R elating to G ro u p III H azardous Substances. G ov­ e rnm ent G azette, 14 April 1989; Vol 286, N o 11823. 14. Lasers - m ore th an “m eets the eye”. SA LU S February/M arch 1987:11. * CLASSIFIED ADVERTISEMENTS GEKLASSIFISEERDE ADVERTENSIES SITUATIONS VACANT BETREKKINGS VAKANT ELLISRAS Fisioterapeut benodig by 'n privaat praktyk te Ellisras. KONTAK: Marlien d e Ridder by (01536) 34184(h) o f (01536) 35424(w). PINETOWN/HILLCREST Full tim e or part-tim e physiotherapist required in Pinetown or Hillcrest for our expanding practice. Orthopaedics, sport in­ juries, rehab interests. Excellent salary & working conditions. CONTACT: Judy Jacobs (031) 72-3300 or 765-5244. SPRINGS Full or part-time physiotherapist required for private practice -hospital work, from September 1991. CONTACT: Kim d a M otla or Lynne Isles (011) 56-6911 (w) (011) 743-2740 (h) or (011) 818-2776. HIGHLANDS NORTH Physiotherapist required full tim e or afternoons for ortho­ p a e d ic an d sports injury practice. CONTACT: Ivan Levinrad (O il) 887-2420. JOHANNESBURG Woodside Sanctuary, a hom e for mentally an d physically ha nd ica p p e d children, requires a part-time physiotherapist. Knowledge o f physiotherapy in neurology will b e a reco m ­ mendation. CONTACT: Matron F d e Villiers (011) 726-7318/9(w). VEREENIGING Dringend nodig vollydse fisioterapeut in privaat praklyk. KONTAK: Karen Swanepoel (016) 48052 alle ure. WORKING HOLIDAY IN THE UK CONTACT: Dr John Galt, P O Box 1063, Richmond 3780: Telephone (03322) 2554 OR Dr Chari Laubscher, P O Box 12099, Centrahil, 6006: Telephone (041) 51-3780. JOHANNESBURG Full tim e physiotherapist required from July 1991. Mainly rooms an d paediatric chests with some general hospital work. Experience in Maitland etc. welcom ed. Conditions of service are above average and flexible. CONTACT: Dawn Hansen (O il) 442-8970 or p a g e (O il) 720- 1661 C o de 3600, or write to 16 Wells Avenue, Parkwood 2193. UNITED STATES Physical Therapists w anted to work in a variety o f settings, in ' various geog raph ica l locations in the USA. Minimum o f one year com m itm ent. Will assist with licensure, working visa an d job counselling. Send resume. Photo desirable. Include address an d telephone num ber (include city code). SEND TO: Health Search, 28816 Eight Mile, Suite 105, Livonia, Michi­ ga n 48152, USA. May call collect (belween 10 a m a n d 4 pm . Eastern Stand­ ard Time, M onday to Friday) (313) 471-3893. KRUGERSDORP Physiotherapists required for West Rand CP School, approxi­ m ately 25 minutes' drive from major centres. In service train­ ing available. CONTACT: Mrs E J Proudfoot (O il) 665-1267/8. OOS-RAND Fisioterapeut benodig vir praktyk In Oos-Rand. KONTAK: Mev 1 H O dendaal (011) 896-4712 na ure. Continued on p a g e 33... Physiotherapy, May 1991, vol 41 no 2 Page 27 R ep ro du ce d by S ab in et G at ew ay u nd er li ce nc e gr an te d by th e P ub lis he r (d at ed 2 01 3. )