In medicine, image-wise information (for example, x-ray image or thermogram) is obtained to diagnose diseases and to test the results of treatment. Being sometimes registered at low signal-to-noise values, it is not always sufficient to solve a specific problem. A method of repeated examination is widely adopted in medicine, by which it is possible to get a succession of images. Techniques of image transformations, involving detection of equipotential zones (equidensitograms, isotherms, etc.), as well as usage of pseudocolor image transformation are also widely used, thus facilitating the subsequent utilization of transformed images by the physician.

The temperature increases in biological tissues irradiated by a C.W. CO₂ laser beam have been calculated through the classical heat equation. The temperature behaviours, as a function either of the spatial coordinates or of the irradiation time, are obtained and they are confirmed by preliminary experimental results. The energy penetration into the biological medium, due to the thermal diffusivity, is pointed out and a simple relationship between the superficial and the depth coordinates, relatively to the same isotherm, has been found.

Human Cadaver prostate tumors and canine prostate glands in vivo were irradiated by Nd:YAG laser with different power levels and pulse durations. Temperature measurements were carried out by an arrangement of micro thermo couple, digital volt meter and computer in different layers of the prostate and the rectum. The temporal and spatial temperature measurements showed a good correlation with the histological findings. Endoscopic laser irradiation of prostatic carcinoma in man was performed after TUR. There was a large penetration depth resulting a deep necrosis, but no perforation and no changes in the rectum were to be found also after high power laser irradiation.

There are two nonionizing radiations that are used in medical therapy: ultrasound and laser light. The first is mechanical in nature, the second is electromagnetic, nevertheless, they have a common feature: both are coherent. The mechanisms involved in their biological effects are in both cases far from being understood. Recently, it has been claimed by several authors that laser radiation of noninvasive intensities may promote tissue repair. The same was claimed for ultrasound irradiation already more than thrity years ago. With other words, two radiations of basically different nature give identical biological results. The question arises whether this is only a coincidence or there are common features that cause the observed biological effects. In our already reported experiments we have shown that coherence cannot be the reason for the found tissue repairing effects. Now we wish to report on further observations, and compare the results of various researchers using ultrasound and laser, respectively, in their studies to clear up the mechanisms of the biological effects of these radiations.

Flower inflorescences can be induced directly on root explants from the late variety of chicory cultivated in vitro. In vitro explants require cold treatment and long days to produce flowers. Initial studies on the level of endogenous phenolics and cytokinins in root explants during chilling treatment showed important changes and similar studies were desirable on the effect of long day treatments. However, during long days it is quite difficult to know if variations in these compounds depend on the trophic effect of light, i.e., photosynthesis or on the photoperiodic effect, i.e., tautomeric change in the structure of phytochrome. To separate photoperiodic effects from photosynthetic effects, explants were maintained in short days (10 hours light) and given photoperiodic induction by very brief irradiation with a dye laser producing 660 nn light of 150 mw/cm². Controls in short days do not flower but explants irradiated for only 0.5 minute by the laser produced flowers. Significant changes in dicaffeylquinic acids (isochlorogenic acid) were obtained after only 7 seconds irradiation which are also correlated with flower induction. The results suggest that laser irradiation may prove important in agricultural practice.

The results of the operative treatment of brain tumors are considerably influenced by the surgical managements of the surrounding tissues. Edema, contusion, hemorragic soffusion,necrotic phenomena and impairements of C.S.F. circulation considerably influence the post-operative course especially in patients in whom the critical point of the rising of the intracranial pressure is reached. In this last year we have completely modified the operative techniques of the removing of some brain tumors (capsulate and deep tumors: meningiomas, acoustic neurinomas, pinealoma and hypophisis adenomas) by using the association of the operatory microscope, the CO₂ LASER beam and the CUSA. The microscope allows a control of the topography of the lesion and its vessels. By using the CO₂ LASER beam we can get a very precise section of the nervous tissues with very limited secondary effects; the hemostasis in the arteriolar and precapillary area is also considerably efficient. CUSA is a new instrument utilizing the most advanced ultrasonic concepts and techniques. The oscillation of a tip vibrating,at 23.000 times per second removes neoplastic tissue layer by layer; the tissue is fragmented and at the same time is aspirated and the operatory field is irrigated. By this techniques we have been able to improve considerably the post-operatory course and to extend the surgical indications.

Medical iconography is one of the fields of increasing importance where the physician should particularly welcome the cooperative attention of the biophysicist and his accompanying infusion of sometimes radical scientific methods. The scope of this report is to describe a new approach to medical iconography, which is based on psychophysics and, therefore, it might stirr up emotion and create controversion: but just this is our intention, since we are convinced that the debate of this idea is important enough to be laid before an audience of experts of 3-D imaging systems. Our proposal originates from the recognition that perceiving an information pattern is more than witnessing a signal pattern from which the information pattern is processed. Perception is namely an internal adaptive reaction to the demands made by the world by way of receptor organs, or as internal "updating" of the organizing system to match incoming signals. This can be done in many ways depending on what aspects of information patterns are significant. Our nonconscious a priori knowledge is introduced for grouping the tiles of the signal mosaic, to organize them to perceive what we believe is there. This, however, means that signals of nonadequate stimuli may also be processed in a form which is usually described as "optical image". We are describing techniques which use nonadequate stimuli to get information from 3-D space, and which allow to locate the percepts subjectively in space somewhat similar way as a virtual image of a reconstructed hologram is perceived in space.

As reported by Mr. Frank and Mr. Keiditsch the neodymium YAG laser seems to be the most potent laser in endoscopic applying based on its biophysical properties. It's my task to speak about our surgical procedure and our clinical results using the neodymium YAG laser.

Application of lasers as cutting or coagulation instruments is based on the conversion of light energy into heat in the irradiated tissue. The extent and degree of the thermal action depends on the beam geometry and the energy of the incident light, as well as on the optic and thermal properties of the tissue. The extinction behavior in the tissue differs for the various laser systems employed in medicine. A comparison is made with Nd:YAG laser and those of the argon and CO₂ types. For the transurethral use of laser beams in urology a special lasercystourethroscope has been developed. This is a modified Albarran attachment using a highly-flexible quartz fiber to transmit the laserlight. The proximal end of the light conductor is used without any sealing window and can be bent through up to 800.

Different groups of quantities are defined for optical radiation, which can be described by a general equation. One of these groups includes quantities of photobiologically effective radiation. These quantities and the relative spectral evaluation functions of some photobiological effects are described. The measuring equipment for these photobiologically effective radiation quantities must fulfil special demands, which are stated. Some precise meters are described.

During replication of African swine fever virus (ASFV) the formation of abberant cylindrical forms is sometimes observed, as it has been also reported with other icosahedric viruses (1).

The three-dimensional interpretation of molecular structure images is of great importance since the properties of biological molecules depend on their spatial arrangement.

For the measurement of photobiologically effective radiation silicon photodiodes are good qualified. Since most of the spectral photobiological efficacy functions have parts of their sensitivity in the ultraviolet wavelength-region, the usual technic of spectral correction cannot be applied. Therefore new methods are described, by which exactly corrected cells for the different efficacy functions can be produced.

Technique of holography is applied for 3-Dimensional and dynamic viewing of serial roentgenograms with special emphansis on total display of serial neuroradiograms and computerized tomograms (CT Scan). Although holographic stereogram is at present no better than conventional stereoscopic technique, our multi-tomogram holography appears to provide 3-Dimensional viewing of CT Scan images which is based upon new principle.

The reconstruction of a two-dimensional image from one-dimensional projections can be a nondestructive method to achieve a sectional image, e.g. in medical diagnostics, where it is called trans-axial tomography. An analog reconstruction theory based on deconvolution is discussed and illustrated by digital computer simulations. A coherent-optical realisation of the deconvolution is described and experimental results are shown.

In optical or electron microscopy serial thin or thick sections permit the measurement of the X, Y, Z three-dimensional coordinates of microscopic biological structures. These data permit geometrical parameter computer calculation of the object and its automatic graphical representation. The photographs of serial sections reproduced on lenticular film, or the stereogram of thick sections give a three-dimensional vision of the object studied on the quantitative plane. The association of these various ways of investigation realised for the first time since 1968, define an original technique of three-dimensional study of macro or microscopic biological objects. New examples of the application of this method to the study of the plant chromosomes, are presented.

One method presently used to repair broken jaws consists of the use of an adapted metal clamp. This clamp must be big enough to replace the bone structure in the transmission of stresses, but as small as possible to minimize the perturbations caused to the patient by its implantation. Therefore, it is necessary to know, with precision, the behavior of the jaw when submitted to a force, to characterize the lines of force and to study their dynamic behavior. It is then possible to determine the resistance of the bone through holography.

Holographic interferometric investigations were performed in male giant rabbits (n=10) with and without bladder tumors. Double impulse ruby laser technique was able to detect elasticity changes of the bladder wall caused by tumors. The reproducibility of the experimental results was tested in vivo and in vitro. Healthy and tumorous changed regions of the bladder show a different stretch behavior in response to alterations of internal pressure.The method was found applicable to organic tissue without destruction of the tissue. Holographic interferometry was found to be sensitive method for distinction between normal and tumorous regions of the bladder wall. The results encourage the construction of a designed endoscope for holographic medical diagnostics.

Patients with osteomalacia often complain of back pain or diffuse peripheral bone aches where a mechanical component warrants closer investigations. In order to study the stress-strain patterns in whole human bones and the influence of the degree of calcification upon these patterns, normal bones are submitted to stress and holographic studies are performed prior to and after demineralization. Interpretation of fringes is delicate because the type of loading must be the same in all the experiments with the same bone. Or the demineralization can change non uniformaly the nature of the osseous inhomogeneous structure and caution must be taken to avoid resulting change namely in momentum. Displacements components must be determined in each face of the bone and the calcul of stresses is made in a first step with assumption of equivalent homogeneous material. The problems arrizing in the machanical behaviour of bones are studied experimentally with the various stress analysis techniques. Among these holographical interferometry proved to be particularly well suited because of its high sensitivity, the rough bone surface needs no preparation and it yields the whole deformation field of the surface. Unfortunately the mechanical comportment of the osseous material depends of many factors and the demineralization namely can change non uniformaly the nature of the inhomogeneous structures like bones and caution must be taken for the interpretation of holographic fringes : because of structural variations in bones, apparently similar types of loading can be different namely by evolution of the position of the neutral axis for momentum. Those phenomena will be analysed in different examples. If estimation of demineralization effect is desired, for instance by measurement of appropriated change in elastic modulus, it is important to know any variation in the loading conditions due to specific changes of the material. The first problem considered concerned the measure of Young's modulus E and Poisson's ration of a tigh-bone or tibia. Small test specimens of constant rectangular section are cut out and submitted to pure bending. Classical double exposure holograms are recorded, with the directions of lighting n₁ and observation n₂ of the specimen nearly parallel to the normal Oz by use of a mirror. (cfr Figure 1).

A laser interferometer is described including a reference mirror mounted on a piezo-electric translator (allowing for follow-up control at low frequencies or scanning of the interference fringe system) and a Pockels cell which permits to modulate the phase of the reference beam and calibrate the apparatus. This interferometer has a sensitivity of approximately 0.01 nm and allows real time studies of the tympanic membrane displacements to be made in the living guinea pig undergoing the action of acoustic stimuli such as pure tones or impulse noise.

Clinical evidence suggests that blood flow in the retinal vessels varies in progressing diabetic retinopathy with a significant increase in the advanced stages. The changes of the flow in the blood vessels may serve as a monitor of the disease. Despite their importance direct blood flow velocity measurements are not easily obtainable. The paper communicates recent advances in the development of a laser Doppler anemometer for the determination of in-vivo retinal blood velocity and provides information relevant to the flow of blood in the human retina. The anemometer is integrated, self-aligning and operates with backscattered light. The influence of the important design parameters is qualified. Problems of light absorption and diffusion by blood corpuscles pertinent to laser Doppler anemometry as well as focussing of the control volume on the retinal arteries are discussed as is the influence of wall scattering on the signal-to-noise ratio. The optical arrangement used for this purpose can, with small modification, be fitted to a slit lamp for simultaneous clinical observations and measurements in the human retina. For the present measurements, it was used to obtain measurement with blood flowing in glass tubes of inside diameter 75 and 100μm. Based on experience with two methods of processing the Doppler signals, an alternative approach is proposed.

A holographic method to determine the Hamming distance between the states of the system being diagnosed is proposed. It is shown that the reverse paraphase coding should be used for recording input and pattern transparancies. Experimental results are presented.

A clinically useful method using hologram interferometry to measure deformations in upper complete dentures is described. Real-time and sandwich holography have been used both to measure deformation as well as to insure proper repositioning of the dentures on the mea-surement stand.

Holographic interferometry has been applied to the observation of mass transfer effects in two membrane separation processes : electrodialysis and ultrafiltration. In the case of electrodialysis, a mathematical model has been developed which predicts the form of the concentration profile between the ion-exchange membranes of an electrodialysis unit, as well as the limiting current which flows through the system when the solution concentration at the membrane surface approaches zero. The concentration profiles observed by holographic interferometry have been used to test the validity of the proposed model. Work on a similar comparison of a mathematical model with interferometric observations for the case of ultrafiltration is now under way. Here the results of the measurements are of particular interest, because the nature of the boundary layer is widely disputed.

Laser speckle is an interference phenomena which is always present when a laser is used. Time-average speckle interferograms of the left and right side of the chest of a normal healthy subject were recorded at the Fourier transform plane on a fine grain photographic plate, while the subject held his breath. The interferogram was analysed by the point wise method and a graph was drawn between the position and the displacements at corresponding points on the chest wall. The associated displacements of the chest wall due to heart action are correlated with cardiac function.

The cochlea of the inner ear has attracted the attention of investigators in a wide variety of fields from physics to physiology. Of particular interest is the question of how much signal processing occurs before sound waves become neural codes. Studies with properly scaled mechanical models have revealed much qualitative information which correctly corresponds to physiology observations, such as a place principle and traveling wave motion of the basilar membrane. This membrane, which supports the neural sensors, resembles a slender tapered plate of trapezoidal platform with a length of about 35 millimeters and a width of a few tenths of a millimeter. This divides a tube of variable cross-sectional area into two chambers (scala vestibuli and scala tympani). A mechanical model, twenty-four times life size, that maintains dynamical similarity has been tested using both time averaged and stroboscopic holography. This model has been tested with both viscous and inviscid incompressible fluids. Also the thin plate, which represents the basilar membrane, has been modeled by a lossless material (aluminum) and a material with internal damping (polycarbonate). Results of the holography study are presented and compared to a parallel theoretical study. In the lossless case pure nodal patterns are observed and the prominence of the place principle increases with decreasing fluid density. At low frequency (corresponding to less than 500 Hz in the ear) with a viscous fluid the steady state sinusoidal response can be adequately described by a one dimensional theory. The waves are a combination of travelling and standing waves. The travelling component is solely a dissipative effect. Discrete resonances are readily observed in this frequency range. At higher frequencies dissipation smooths out the resonance effect. Also at higher frequencies three dimensional fluid motion becomes highly significant.

We report on two distinct techniques involving picosecond laser pulses; for stereometry or tomoscopy experiments, we use a light scattering technique with a mode-locked Nd³⁺ glass laser; it provides a submillimeter depth resolution. The spectroscopy of ultra short phenomena are obtained with a subpicosecond amplified mode-locked dye laser; some preliminary results concerning the process of the cooperative mechanism taking place in the photolysis of hemoglobin complex are presented.

Liquid crystal is used with full success, mainly in breast cancer detection, skin disease, scrotal disease, and veterinarian experimentation, in addition to industrial quality control (mechanical and electronic circuitry testing). The importance of the results of these uses demonstrates the necessity of improving the spatiothermal resolution and isothermic possibilities. This work introduces new manufacturing processes of encapsulated liquid crystal mixtures selected for specific characteristics. The coating of the liquid crystal-Is explained, the accuracy measurement and testing are exposed, with all the new applications possible due to the high quality of the product. Comparison of special cases of old sheets and new ones are detailed. New potential uses and developments are discussed.

A thermal imaging system for medical purpose has been developed. The primary mirror of the optical system is a spherical reflection mirror. A hexagonal prism is used as a scanner to obtain a large field of view. Every picture has 90.000 resolution elements. The temperature resolution is better than 0.2°C. The instrument displays various modes of thermograms and can give the real temperature by three digit numbers. It has now been approved for production.

A technique for quantitative inFrared thermography has been developed for the evaluation of bone and joint disease. By on-line image processing, a Thermographic Index has been used to study both normal and diseased joints. These values have demonstrated the effect of drugs, to a high degree of sensitivity. Statistical studies on these indices can be employed in the clinical testing of new compounds, as well as the effects of other treatment such as surgery. The technique is rapid, simple and safe, with advantages over radioisotope investigations in the long term follow up of chronic disease.

Thermal noise detection in microwave frequency range can lead to a non invasive subcutaneous temperature measurement in the living tissues. Several clinical aoplications are mentioned (cancer detection, brain temperature measurements, ergonomics). First experiments, and computations on thermal models show a possible achievement of a new method concerning a thermal pattern recognition.

More than a hundred cases of thyroidal, osteoarticular, facial or intracranial pathologies have been explored with microwave thermography at 9, 30 and 68 GHz. We have been able to detect deep lesions such as those of femoral head or lumbar spine, or cerebral tumors, with the help of this technology.

Radiothermometric investigations have been carried out on breast cancer patients and on patients with tumors of various localizations and histologic types (liver,thyrold,...) (55 cases), by means of a high sensitivity hyperfrequency radiometer operating at 9GHz.The findings were analyzed as follow: (a) comparison between microwave thermal mapping and infrared thermography; (b) correlations with various morphologic and thermal parameters (depth and size oftumor thermal conductivity, vascularization and x-ray structures of tissues). Microwave radiometry seems to be able to provide significant information on meta-bolism and thermal conditions of subcutaneous tumor tissue, especially under those clinical situations where infrared thermography does not work.

Optical devices and instruments are, in general, widely used in medicine and in biology. Development of different branches of these sciences became possible, due only to optics, for instance, cytology, i.e. the study of cells, or microbiology, dealing with micro-organisms, appeared only after one of the main optical instruments, the microscope, had been developed (1) . Now, the optics itself, enriched with the achievements of electronics undergoes the period of tremendous upheaval due to lasers, high-sensitive light detectors and so on. The last ones made it possible to cover with scrupulous investigation in visible spectral zones and also to make the registration process itself automatic (2).