I- Applications Of Thermal Effects-Most therapeutic applications of laser derivate from thermal effects. When the laser beam is focused on a small area, it warms up the tissues which retract (coagulation); if the heating is more intense, tissues may be vaporized. Coagulation is used either to destroy small tumors or to stop an hemorrhage (hemostasis); in the latter case, the thermal retraction will induce the closing of the vessel lumen which secondly will be obstructed by a blood clot (thrombosis).

C'est de tres loin le mecanisme predominant dans les applications therapeutiques du laser. En concentrant le flux lumineux sur une surface redui-te, le laser chauffe localement les tissus qui se retractent (coagulation) pour etre elimines ensuite (detersion) ; si on chauffe plus intensement, les tissus peuvent etre volatilises. La coagulation est utilisee soit pour detruire de petits phenomenes tumoraux qui seront elimines lors du processus de detersion, soit pour arreter une hemorragie (hemo-stase) ; dans ce cas la retraction thermique des tissus va provoquer la fermeture de la lumiere des vaisseaux qui seront secondairement obliteres par des caillots formes sur place (thrombose). Par volatilisation it est possible de detruire des phenomenes tumoraux plus importants que ceux at-teints lors d'une simple coagulation. Si la zone volatilisee est tres etroite (de 0,1 a 1 mm) on obtient un effet de coupe avec une excellente hemostase au niveau des berges. Certes ces deux processus - coagulation et volatilisation - peuvent etre obtenus par d'autres procedes : echauffement par contact (sonde thermique) ou effet Joule (courant electrique haute frequence). Le laser a l'avantage de ne necessiter aucun contact mecanique entre le vecteur d'energie et les tissus ; on peut alors predire correctement la repartition d'energie au niveau des tissus et les effets sont tres repro-ductibles. Par ailleurs, l'absorption tissulaire variant considerablement avec la longueur d'onde on peut choisir la source laser en fonction des effets desires.

The experimental angular aperture of step-index fibres is always smaller than the theoretical aperture. Furthermore, the light power transmitted within the fibre up to the angular aperture is the more attenuated the greater the angle of incidence is. An expression of the light power transmitted within the fibre is given, which shows that the first phenanenon is due to variations of the fibre diameter core and the second phenamenon to the cladding absorbance.

On constate experimentalement que, d'une part les fibres optiques a saut d'indice ont une ouverture angu-laire toujours plus faible que celle que la theorie laisse prevoir et d'autre part, qu'en-dessous de cette li-mite la lumiere transmise est d'autant plus attenuee qu'elle est introduite sous une incidence plus grande. Une modelisation de la puissance transmise dans la fibre est proposee, qui permet d'expliquer le premier phe-namene par les variations du diametre du coeur de la fibre et le second par la arise en campte de l'absorbance de la gain optique.

The formation of spherical or elliptical terminations on optical fibres by heating produces an integral microlens element which can be used to improve the coupling efficiency between a laser diode and a fibre or between two fibres, or to focus the output beam for biome-dical applications. A novel fabrication technique is outlined, which uses the laser light energy delivered by the fibre itself. The method is easy and reliable, and is applicable to all types of multimode fibres, even of large core diameter.

The construction and characterization is described of enlarged taper ended fibers to be used in laser radiation delivery systems for medical applications. The measured near and far field patterns are also compared with those evaluated by a ray optics method. Experi-ments utilizing such tapered fibers coupled to a Nd:YAG laser, performed at the S. Maria Nuova Hospital of Florence, are also reported.

In order to perform continuous and on-line monitoring of in situ normally perfused living organs metabolism, we developed a laser fluorimeter. Herewith are reported - The bases for the realization of this device : tissues optical properties, pulsed laser signals, optoelectronical processing. - Its description : nitrogen laser, dye laser, optical fiber, analog and digital circuits. - Current physiological applications in in vitro, in vivo, in situ experimental models. Together with the first experiments undertaken to apply this method in clinical investigation.

Dans le but de pratiquer en continu et en temps reel (monitorage), la surveillance du metabolisme (rapport d'oxydo-reduction tissulaire/rapport NADH sur NAD) in situ d'organes vivants normalement perfuses, nous aeons realise un fluorimetre laser dont nous rapportons : - Les principes de conception (proprietes optiques des tissus, traitement opto-electronique des signaux laser pulses). - La description (laser a azote, laser a colorant, fibre optique, circuits analo-giques et digitaux). - Les applications deja effectuees en physiologie (modeles experimentaux in vitro, in vivo et in situ). - Ainsi que les premieres experimentations pratiquees en vue de son application a l'investigation clinique.

First of all, we recall the various mechanisms of interaction between laser radiation and biological systems. Then, the factors of the hazards to the eye are analysed: physical factors in connection with the emission (wave lenght, point or extended source, irradiance on radiant exposure, pulse shape and pulse repetition frequency), factors in connection with the physiological state of the eye (pupil size, dccomodation, look orientation, eyelid blink reflex, optical viewing instruments). The skin hazards are studied in function of emission parameters (wave lenght, irradiance or radiant exposure time, pulse shape and pulse repetition frequency) and local vascularisation. From these data, the Maximum Permissible Exposure (MPE) is defined. The various values of MPE edited by the T.C. 76 of the I.E.C. are commented.

In an hospital, the need for an electronic communication network is increasing along with the digitization of pictures. This local area network is intended to link some picture sources such as digital radiography, computed tomography, nuclear magnetic resonance, ultrasounds etc...with an archiving system. Interactive displays can be used in examination rooms, physicians offices and clinics. In such a system, three major requirements must be considered : bit-rate, cable length, and number of devices. - The bit-rate is very important because a maximum response time of a few seconds must be guaranteed for several mega-bit pictures. - The distance between nodes may be a few kilometers in some large hospitals. - The number of devices connected to the network is never greater than a few tens because picture sources and computers represent important hardware, and simple displays can be concentrated. All these conditions are fulfilled by optical fiber transmissions. Depending on the topology and the access protocol, two solutions are to be considered - Active ring - Active or passive star Finally Thomson-CSF developments of optical transmission devices for large networks of TV distribution bring us a technological support and a mass produc-tion which will cut down hardware costs.

Dans l'hOpital, le besoin d'un reseau de communication electronique ne cesse de crottre au fur et a mesure de la numerisation des images. Ce reseau local a pour but de relier quelques sources d'images telles la radiologie numerique, la tomodensitometrie, la resonance magnetique nucleaire, l'echographie ultraso-nore etc..., a un systme d'archivage. Des consoles de visualisation interacti-ves peuvent etre utilisees dans les salles d'examens, les bureaux des medecins et les services de soins. Dans un tel systme, trois caracteristiques princi-pales doivent etre prises en compte le debit, la longueur du cable et le nombre de connexions. - Le debit est tr?)s important, en effet, un temps de reponse maxima de quel-ques secondes doit etre garanti pour des images de plusieurs millions d'ele-ments binaires. - La distance entre connexions peut etre de quelques km dans certains grands hopitaux. - Le nombre de connexions au reseau ne depasse jamais quelques dizaines car les sources d'images et les unites de traitement representent des materiels importants, par ailleurs les consoles de visualisation simples peuvent etre groupees en grappe. Toutes ces conditions sont remplies par les transmissions sur fibres optiques. Selon la topologie et la methode d'accNs, deux solutions peuvent etre envisa-gees : - Anneau actif - Etoile active ou passive Enfin, les developpements de Thomson-CSF en composants pour transmissions optiques pour les grands reseaux de tel4distribution nous apportent un support technologique et une production de masse qui diminuera les collts du materiel.

The utilization of coherent bundle fiber optic endoscopy for the diagnosis of disease has dramatically altered patient care worldwide. The ability to flexibly access organs and tissue has provided the clinician with a tool that permits evaluation of disease while causing little trauma or invasion to the patient. While great strides in diagnostic endoscopy have been made, principally due to coherent bundle fiber optics, the progress in therapeutic endoscopy has been slow. Most standard endoscopes are equipped with small, hollow biopsy channels that permit the clinician to take small tissue specimens. A system of mechanical devices that snare, bite or tear tissue have been developed for this purpose. Many attempts to extend the diagnostic endoscope into the therapeutic world have been attempted. Monopolar and bipolar coagulation electrodes, as well as cryosurgical devices have been developed to destroy tissue. The most promising therapeutic tool for endoscopic use is laser energy delivered by fiber optics.

Argon laser has a C.W. emission and emits several lines between 487 and 544 nm. This radiation is well absorbed by living tissue and especially where there are red pigments (hemoglobin, myoglobin) or black pigments (melanine). Therapeutic applications mainly use thermal effects. By varying the parameters, (optic power, size of exposed area, exposure time) ; one can obtain a coagulation (maximal tissular temperature 60° - 80°) or a vaporization (temperature over 100°). Section occures when the vaporized area is very thin (below 0.5 mm).

Le laser a argon ionise est un laser a emission continue, reglee en general en multiraies de 487 a 544 nm. Le rayonnement de ce laser est bien absorbe par les tissus vivants, avec une action preferentielle au niveau des pigments rouges (hemoglobine, myoglobine) et noirs (melanine). Le laser a argon est princi-palement utilise en therapeutique pour ses effets thermiques : en fonction du choix des parametres (puissance optique, surface exposee, temps d'exposition) on peut obtenir une coagulation (temperature optimale au niveau des tissus 60° - 80°) ou une volatisation (temperature superieure a 100°). Si la zone volatilisee est tres etroite (inferieure a 0,5 mm) on obtient un effet de coupe. Par rapport aux deux autres lasers egalement utilises pour leurs effets thermiques (CO2 et Nd. YAG) l'argon a des effets intermediaires : la coagulation sera plus superficielle qu'avec le Nd. YAG et la volatisation plus profonde qu'avec le CO2. Lors de la coupe, la necrose sur les berges sera egalement plus importante qu'avec le CO2.

Si 1' utilisation du laser a argon en ophtalmologie remonte a 1968, depuis quelques annees, nous disposons de laser monochromatiques : le laser a krypton rouge et le laser a argon vert. Des etudes en microscopie optique et electronique ont ete ef fectuees sur des singes. Le maximum d'alterations se situe au niveau de la choroide avec le laser a krypton et au niveau de 1' epithelium pigmentaire avec le laser vert a argon. Ces etudes nous ont permis de preciser les indications des laser monochromatiques. Ainsi, en clinique, les neovaisseaux sous retiniens constituent une de leurs indications essentielles en particulier dans la region du pigment luteal. Par ailleurs, le laser a krypton a une bonne transmission a travers des milieux oculaires troubles, et it nest pas absorbe par le sang. Le laser a argon vert au contraire, permet la destruction d'a-nomalies microvasculaires retiniennes.

Our experience with Nd YAG Laser in bronchology is now based on over 1500 endoscopic resections. L. TOTY had previously carried out animal experiments to asseq5the possibilities of this new technique. The first patient was operated on in November 1978. Once the first teething troubles of any new technique were solved, its indications were soon determined. All technical difficulties were successively, if not completely mastered, at least overcome. As a result, in the course of the past four years, A. COLCHEN and I, with the help of our anestheeic colleagues, have been able to improve both the method and the instrumentation.

Notre exp4rience du Laser YAG en bronchologie porte actuellement sur plus de 1500 resections endoscopi-ques. L. TOTY avait experiments sur l'animal les possibilites de cette methode nouvelle. C'est en novembre 1978 que le premier malade 6-bait traits. Apres les inevitables hesitations de depart d'une technique que nous inaugurions, les indications allaient se preciser. Les obstacles materiels, un par un, etaient sinon tout a fait resolus, au moires surmontes.Ainsi, au cours de ces quatre annees, j'ai &Le amens avec A. COLCHEN et notre equipe d'anesthesistes a affiner progressivement une methode et son instrumentation.

Quartz fibers not protected by a gas stream and used in tissue contact can work virtually indefinitely due to "self cleaning" and "regeneration". Tissue lesions are similar to those obtained with conventional devices.

Les fibres en quartz, non protegees par un courant de gaz et placees au contact du tissu, peuvent etre utilisees pratiquement indefiniment grace a un "autonettoyage" et une "regenera-tion". Elles provoquent des lesions tissulaires semblables a celles obtenues avec les fibres conventionnelles.

The Nd:YAG laser has become a coagulation instrument, which has found acceptance in interdisciplinary surgery. The main contributors are its highly efficient coagulation capability in interaction with tissue and the fact that the Nd:YAG laser beam can be transmitted by means of a simple quartz-glass fiber. Appropriate systems and instruments for transmission and operation have been developed for the various applications in neurosurgery, pulmology, gastroenterology, urology, gynaecology and dermatology. Operation methods in open and endoscopic surgery under use of several hand held devices and flexible as well as rigid endoscopes are being demonstrated by clinical examples of application.

The interest in Photo Radiation Therapy (PRT) has increased dramatically in the last two years. As the requirements for the evaluation of the technique have been established we have responded by designing dedicated laser equipment.

Ladies and gentlemen, 23 months ago I treated the following emergency cases in my surgery : 1) A man of 53 suffering from dyspnoea (clinically speaking he was a case of exniratory bradypnoea). He had just been hospitalised for a month and had been undergoing cortisone treatment. I made him sit, and b/ irradiating each of the stellar ganglions for six minutes by laser at an impulse wave length of 6 in low frequency I freed up this patient, who started to breathe normally. 2) Some time after this : A child of 7 came to see me. He was suffering from an attack of asthma. I passed each of the stellar ganglions under the laser at impulse wave length 6 in low frequency for 4 minutes. The child witnes ed his attack calming down. In view of these two cases I decided to organise a research project.

Mesdames, Messieurs, y a 23 mois, je recevais l'urgence suivante dans mon cabinet medical : 1) Un homme de 53 ans, dyspneioue (cliniquement it etait en Bradypnee expiratoire). Il venait d'être hospitalise 1 mois et avait ete place sous cortisone. Je le fais assoir, et j'irradie avec un laser sur chacun des ganglions stellaires pendant 6 minutes je debloque ce malade qui se met e respirer normalement. 2) Quelques temps apres : C'est un enfant de 7 ans que je regois en crise d'asthme. J'irradie sur chacun des ganglions stellaires pendant 4 minutes une onde laser d'impulsion 6 et en basse freouence. L'enfant voit s'estomper la crise d'asthme. Devant ces deux cas, je decide d'organiser un travail de recherche.