Irradiation device for therapeutic treatment of skin diseases and other ailments

Abstract

The invention relates to an irradiation device and method for the treatment of totally or partially cell-mediated inflammations of the skin, the connective tissue and the viscera, viral and other infectious diseases such as HIV and prionic infections, fungal infections of the skin and the mucous membranes, bacterial diseases of the skin and the mucous membranes as well hand eczema and anal eczema which comprises at least one irradiation device to irradiate a surface treatment area where the wavelength of the emitted radiation to a treatment area is longer than 400 nm and comprises at least one spectral band between 400-500 nm while the radiation device has a gas discharge lamp containing at least gallium, indium or their respective halides as irradiation source, means that less than 7% of the overall optical output are emitted in the UV range, wherein at least 30% of the optical output are emitted in the range of 400-500 nm; and contains means for the generation of optical pulses towards a treatment area with a power density of the optical pulse peaks larger than 0.5 W / cm2 and smaller than 500 W / cm2. The energy of one pulse relates to 0.05-10 J / cm2.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. application Ser. No. 10 / 094,430 filed on Mar. 8, 2002, which is herein incorporated by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to an irradiation device for therapeutic purposes, especially for the acute or chronic treatment of totally or partially cell-mediated inflammations of the skin, connective tissue and internal organs, viral and other infectious diseases such as HIV or prion infections, fungal diseases of the skin and the mucous membranes, bacterial diseases of the skin and the mucous membranes as well as hand eczema or anal eczema. [0004] 2. Brief Description of the Related Art [0005] Therapeutic irradiation arrangements have been known for a long time, especially in the field of phototherapy of skin diseases. According to the particular application the patient is irradiated with wavelengths between 315-1500 nm. Particularly the...

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Benefits of technology

[0023] The present invention utilizes the discovery that during pulsed irradiation—other than described in the scientific literature—the generation of singlet oxygen during peak power time is higher than during cw-irradiation by several orders of magnitude. Another advantage of high peak powers is the fact that the deeper layers of the skin also receive sufficient irradiation intensity, seeing that usually only a fraction of cw-radiation reaches those deeper layers due to the low penetration depth of blue light. In addition, pulsed radiation energy has a stronger photobiological effect. If we assume an equal cumulated radiation dose of cw-radiation and pulse radiation, and also assume an intensity of 70 mW / cm2 for the cw-radiation, we would see that only 10 mW / cm2 would remain for photobiological effects, since 60 mW / cm2 of the radiation input would be neutralized by dermal antioxidants as a constant off-set. It is obvious that this decrease in photobiological efficiency by constant off-set can be effectively reduced by using pulsed radiation. Pulsed power peaks in the kW power range are only marginally affected by this dermal antioxidant effect. The average energy supply is so chosen as to avoid necrosis of the cells but merely to induce apoptosis. Likewise, the treatment stays below the ablation threshold aimed at in EP 0 565 331 B1. Tissue ablation occurs when energy higher than 2500 J / cm2 is deposited in the tissue within a period of time that does not allow heat exchange between adjacent layers. Due to the time modulation by pulse generation, where the irradiation time is below the relaxation period of the uppermost layer of the skin, in the outer layer of the skin hyperthermia is achieved which can easily be removed. Light in the range of 400-500 nm loses 50% of its energy after 200 μm. The estimated thermal relaxation period for a structure with a diameter of 200 pm is approx. 20 ms, meaning that, assuming a retention period of the light of <20 ms, only the outer layers of the skin are heated without any energy deposition in the deeper layers.

[0030] In order to improve the diffusion of oxygen and the thermal cooling, there is a longer pulse-off interval between a few seconds to a few minutes after a series of preferably, for example, 100 pulses, before generating a new pulse series. due to the extremely long diffusion times of oxygen there may also be applications where just one single pulse is administered before a longer pulse-off interval. These pauses can vary in length from one to several hours. Particularly for the treatment of chronic diseases the irradiation arrangement can be assigned to the patient as, for example, a belt, an irradiation blanket or an irradiation bed so as to give, for example, one pulse per hour. These long pauses make thermal problems or the diffusion of oxygen in tissues negligible.

[0039] Unexpectedly, it was discovered that gallium iodide-doped mercury medium-resp. high pressure lamps do show neither broadening nor an inversion of the gallium emission at 403 and 417, even if the overload is 100-1000 times above normal operating conditions. A gallium iodide-doped mercury discharge lamp run under normal conditions with a discharge current of 1.5 A / cm2 cross-sectional area of the discharge vessel could be run in pulse operation mode with 1000 A / cm2 cross-sectional area of the discharge vessel without reduction or inversion of the gallium emission lines. A possible explanation relates to the fact that metallic gallium has a boiling point of 2200° C. so that the gallium vapor pressure can be neglected even under pulse operation of the lamp. However, there is a disintegration of mercury iodide into mercury and iodine. During the plasma discharge, iodine forms an instable compound with gallium, gallium tri-iodide. Gal3 shows a marked increase of vapor pressure even at rather low temperatures. The absent inversion of the gallium emission could be explained by the fact that Gal3 is only stable up to a certain pressure and there is a rapid disintegration into gallium and iodine if the pressure is increased any further. Therefore a relatively stable gallium vapor pressure can be maintained even if there is rapid temperature increase during pulse operation. After the disintegration of the compound, Gal3 there is a condensation of metallic gallium which does not take part in the discharge and possible self-absorption of the gallium emission. This unexpectedly discovered effect could therefore be related to a paradox constant vapor pressure covering a temperature range between 200 and almost 2200° C. Mercury iodide disintegrates early into mercury and iodine, so that there is always iodine available to form a compound with the gallium. Mercury pressure therefore may increase rapidly with the energy load, thus providing excitational energy for the gallium emission. Due to the relatively stable gallium vapor pressure, most of this energy is emitted as gallium spectrum lines at 403 and 417 nm.

[0044] In another preferred embodiment a pulsed radiation source is operated in simmer mode, thus allowing to increase the pulse slope.

[0045] It is also possible to combine the scan movement with a pulsed radiation source, in order to further decrease the achievable pulse lengths for an assumed treatment area, which is also advantageous in view of thermal relaxation.

[0052] By increasing the irradiated area, the energy density at the surface decreases so that the duration of the widened irradiation area may be longer. This accomplishes that a larger number of absorbing chromophores can be photochemically excited over a longer time interval than would be possible during a short pulse. The absence of radiation peaks within the radiation area impede the local bleaching resp. the local shortage of oxygen. Furthermore, there is a local maximum in the central area of the irradiation field since the scattering of all rays add and increase the radiation in the central area. Depending on the tissue parameters an the spectrum, the optimal irradiation area has a diameter of more than 4 mm and less than 60 mm since by using large diameters the scattering of the marginal rays does not increase the intensity in the central area. By choosing an optimal beam diameter, a higher intensity in the central irradiation area resp. a higher penetration depth can be achieved. A further widening of the irradiation area leads to a decrease in power density proportional to the increase of the area so that no light reaches the deeper tissue layers. Furthermore, the re-irradiation period of ever larger tissue areas shortens so that heat extraction resp. become more difficult.

Problems solved by technology

Up to now, these have been treated with UV-light, which often leads to temporary improvement, but leads also frequently to complications in wound-healing in the long run.

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