Skin radiation apparatus and method

Abstract

The present invention relates to a skin radiation apparatus and method. The apparatus includes a photon radiation unit for generating a line-shaped radiation pattern that extends in a first direction; a movement facility for moving the line shaped radiation pattern in a second direction transverse to the first direction; a detection unit for detecting a skin condition profile; and a control unit for controlling the line-shaped radiation pattern, dependent on the detected skin condition profile.

Claims

1. A skin radiation apparatus comprising: a photon radiation emitter configured to generate a line-shaped radiation pattern extending in a first direction, the photon radiation emitter comprising a photon radiation source having a plurality of elements, each configured to simultaneously generate a respective portion of the line-shaped pattern, wherein the line-shaped radiation pattern is generated without requiring any movement of the photon radiation emitter, a movement facility configured to cause movement of the line-shaped radiation pattern in a second direction transverse to the first direction, a skin condition detector configured to detect a skin condition profile, a controller configured to determine a power density distribution for the line-shaped radiation pattern, that simultaneously has multiple different positive power densities, and is dependent on: the skin condition profile detected by the skin condition detector, a maximum power density above which skin damage would occur, and a minimum power density below which the treatment has no therapeutic effect, the controller being further configured to control the photon radiation emitter to generate the determined power density distribution of the line-shaped radiation pattern having the multiple different positive power densities along the first direction.

2. The skin radiation apparatus of claim 1, wherein the skin condition detector is configured to detect a skin condition profile in a scan region, and wherein the movement facility is configured to cause the line-shaped radiation pattern to traverse the scan region and wherein the controller controls the power density distribution depending on the skin condition profile detected for the scan region.

3. The skin radiation apparatus of claim 2, wherein the line-shaped radiation pattern is applied to a person's skin, the skin radiation apparatus comprising: movement detector configured to detect any movement of the person not caused by the movement facility, and generate a corresponding movement indication signal, wherein the controller is configured to control the power density distribution based on the skin condition profile detected for the scan region and on the basis of the movement indication signal.

4. The skin radiation apparatus of claim 1, wherein the skin condition detector is configured to detect a skin condition profile in a line-shaped detection area.

5. The skin radiation apparatus of claim 4, wherein the line-shaped radiation pattern is targeted at the line-shaped detection area and wherein the movement facility is configured to move the line-shaped detection area to a next position in the second direction after the skin condition profile in the line-shaped detection area has been determined and the line shaped radiation pattern has been applied to the line-shaped detection area.

6. The skin radiation apparatus of claim 4, wherein the skin condition detector is configured to detect a skin condition in a further line-shaped detection area that is positioned ahead in the second direction with respect to a line-shaped radiation area that is irradiated by the line-shaped radiation pattern.

7. The skin radiation apparatus of claim 4, wherein the skin condition detector and the photon radiation emitter are arranged in a common housing that is moved by the movement facility.

8. The skin radiation apparatus of claim 1, further comprising an indication facility for indicating at least one of: a radiation power profile, and a radiation dose profile, scheduled by the controller to be applied at the skin.

9. The skin radiation apparatus of claim 8, further comprising a feedback facility allowing an operator to change at least one of the radiation power profile and the radiation dose profile as scheduled by the controller.

10. The skin radiation apparatus of claim 9, comprising a learning unit for teaching optimal operation of the skin condition detector or controller on the basis of the changes to the radiation power profile and/or the radiation dose profile as indicated by the operator.

11. The skin radiation apparatus of claim 1, comprising a storage facility for storing data related to a therapeutic session.

12. A skin radiation method comprising the acts of: in a skin radiation apparatus: detecting via a skin condition sensor, a skin condition profile of a person's skin, generating via a photon radiation emitter, a line-shaped radiation pattern that extends in a first direction, wherein the generating act comprises utilizing a photon radiation source having a plurality of elements, each element capable of simultaneously providing a respective portion of the line-shaped pattern, wherein the line-shaped radiation pattern is generated without requiring any movement of the photon radiation emitter, moving by a movement facility, the line-shaped radiation pattern in a second direction transverse to the first direction, and controlling via a controller, the photon radiation emitter to generate a power density distribution of the line-shaped radiation pattern having multiple different positive power densities along the first direction based on the detected skin condition profile, a maximum power density above which skin damage would occur, and a minimum power density below which the treatment has no therapeutic effect.

13. The skin radiation method of claim 12, further comprising an act of generating a visible pattern that is isomorphic to at least one of: a scheduled radiation power profile, and a scheduled radiation dose profile, after the skin condition profile is scheduled and before generating the line-shaped radiation pattern.

14. The skin radiation method of claim 13, further comprising an act of changing at least one of: the scheduled radiation power profile, and the scheduled radiation dose profile, upon commands received by the controller from an operator, after generating the visible pattern.

15. The skin radiation method of claim 14, comprising an optimizing operation of the detecting of the skin condition profile, the optimizing operation based on the changes to at least one of: the radiation power profile, and the radiation dose profile, as indicated by the received commands.

16. The skin radiation method of claim 14, comprising an optimizing operation of the generating the line-shaped radiation pattern based on the changes to at least one of: the radiation power profile, and the radiation dose profile, as indicated by the received commands.

17. A skin radiation apparatus comprising: a photon radiation emitter configured to generate a line-shaped radiation pattern extending in a first direction, the photon radiation emitter comprising a photon radiation source having a plurality of radiation source elements, wherein in use, the plurality of the radiation source elements simultaneously provide respective portions of the line-shaped pattern, a movement facility configured to cause movement of the line-shaped radiation pattern in a second direction transverse to the first direction, a skin condition detector configured to detect a skin condition profile, a controller configured to determine a power density distribution for the line-shaped radiation pattern, that simultaneously has at least three different power densities, and is dependent on: the skin condition profile detected by the skin condition detector, a maximum power density above which skin damage would occur, and a minimum power density below which the treatment has no therapeutic effect, the controller being further configured to control the photon radiation emitter to generate the determined power density distribution of the line-shaped radiation pattern having multiple different positive power densities along the first direction.

18. A computer-readable storage-medium that is not a transitory propagating signal or wave, the medium modified by control information including instructions for performing a method for irradiating skin, the method comprising: in a skin irradiation apparatus: detecting via a skin condition sensor, a skin condition profile of a person's skin, generating via a photon radiation emitter, a line-shaped radiation pattern that extends in a first direction, wherein the generating step comprises utilizing a photon radiation source having a plurality of elements, each element capable of simultaneously providing a respective portion of the line-shaped pattern, wherein the line-shaped radiation pattern is generated without requiring any movement of the photon radiation emitter, moving by a moving facility, the line-shaped radiation pattern in a second direction transverse to the first direction, and controlling via a controller, the photon radiation emitter to generate a power density distribution of the line-shaped radiation pattern having multiple different positive power densities along the first direction based on the detected skin condition profile, a maximum power density above which skin damage would occur, and a minimum power density below which the treatment has no therapeutic effect.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects are described in more detail with reference to the drawing. Therein:

(2) FIG. 1A shows a first part of a skin radiation apparatus according to an embodiment of the invention,

(3) FIG. 1B shows a second part of a skin radiation apparatus according to said embodiment,

(4) FIG. 1C shows an embodiment of a line shaped radiation pattern irradiated at a person's skin,

(5) FIG. 2A shows a skin radiation apparatus according to a further embodiment of the invention,

(6) FIG. 2B shows an embodiment of a pattern projected by a part of the skin radiation apparatus,

(7) FIG. 2C shows a skin radiation apparatus according to a further embodiment of the invention,

(8) FIG. 3A shows a first view of a skin radiation apparatus according to a still further embodiment of the invention,

(9) FIG. 3B shows a second view of a skin radiation apparatus according to a still further embodiment of the invention,

(10) FIG. 4A schematically shows a skin radiation apparatus according to a still further embodiment of the invention,

(11) FIG. 4B shows an aspect relating to a use of the skin radiation apparatus of FIG. 4A,

(12) FIG. 5A schematically shows an embodiment of a radiation source in an embodiment of the skin-radiation apparatus,

(13) FIG. 5B schematically shows an embodiment of a radiation source in another embodiment of the skin-radiation apparatus,

(14) FIG. 5C schematically shows an embodiment of a radiation source in again another embodiment of the skin-radiation apparatus.

DETAILED DESCRIPTION OF EMBODIMENTS

(15) In the following detailed description numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail so as not to obscure aspects of the present invention.

(16) The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity.

(17) It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, and/or sections, these elements, components, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component and/or section from another element, component, and/or section. Thus, a first element, component, and/or section discussed below could be termed a second element, component, and/or section without departing from the teachings of the present invention.

(18) Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

(19) FIGS. 1A to 1C show a first embodiment of a skin radiation apparatus. For clarity each of the FIGS. 1A, 1B show a respective part of the skin radiation apparatus. As shown in FIG. 1B, the apparatus comprises a photon radiation unit 10 for generating a line-shaped radiation pattern 12 extending in a first direction x. The photon radiation unit 10, arranged in a housing 5, comprises a photon radiation source 14. In addition the photon radiation unit 10 may comprise optical elements for controlling a beam radiated by the radiation source 14, such as mirrors, lenses, shutters etc. The apparatus further comprises a movement facility 20 for moving the line shaped radiation pattern in a second direction y transverse to the first direction x. The movement facility comprises for example a pair of rails 20 and an actuator 22. During operation the actuator 22 causes the housing 5 with the photon radiation unit 10 to displace in the y-direction along the pair of rails 22. Therewith also the line shaped radiation pattern 12 is displaced in the y-direction. Alternatively the housing may be mounted at a first end of an arm that may be rotated around an axis at its other end. A suitable movement facility is readily available as a state-of-the-art handling robot.

(20) Directions x and y are defined by a plane of the skin that is to be irradiated.

(21) The apparatus further comprises a detection unit 30 (FIG. 1A) for detecting a skin condition profile. In the embodiment shown the detection unit 30 is capable of detecting a skin condition profile for a relatively large region of the skin, e.g. for one side of the body of a patient 1, or for the region formed by the back.

(22) The apparatus further comprises a control unit 40 for controlling a power density distribution for the line-shaped radiation pattern 12 dependent on the skin condition detected by the detection unit 30.

(23) The apparatus may be used in a skin radiation method as follows. First the apparatus detects a skin condition profile of the skin of the patient 1. In this case, as illustrated in FIG. 1A, an image is obtained of the backside of the person in its entirety. Alternatively an image of a more limited portion of the person may be obtained, e.g. the skin of an arm or leg. Subsequently an image processing method is applied to determine the skin condition profile, i.e. the condition of the skin as a function of the spatial location. Methods for obtaining the image and the subsequent image processing methods to determine the skin condition are known as such and are for example described in the co-pending published patent applications WO2008/041162 and WO2007/119202 filed by the same Applicant, as well as in the cited US document. On the basis of the skin condition profile subsequently a radiation power profile is calculated. Although in this embodiment the image of an area of the skin to be treated is taken as a single snapshot, it is not necessary that the required radiation power profile is calculated for this area in its entirety before treatment is started. The required radiation power profile may be calculated for one line shaped area at a time. This allows the required power density profile to be rapidly calculated with simple means. Subsequently, as indicated in FIG. 1B, a moving line shaped area, extending in the x-direction, of the person's skin is radiated with photon radiation. The radiation has a power density distribution that is dynamically controlled according to the skin condition pattern that was detected for said line shaped area. The required radiation power profile for the line shaped area that is irradiated by the line shaped radiation pattern is the power density distribution for said line shaped radiation pattern. FIG. 1C shows by way of example a situation where the line shaped radiation area that is irradiated by the line shaped radiation pattern overlaps three affected regions 2a, 2b, 2c of the skin. Accordingly the line shaped radiation pattern has a relatively high power density in locations 12a, 12b, 12c where it overlaps these affected regions and a relatively low power density (preferably 0) outside these regions. The relation between the skin condition profile and the required radiation dose profile for optimum treatment thereof is known as such. For the healthy skin the radiation dose is preferably as low as possible. For treatment of psoriasis photon radiation doses may be used dependent on the skin type and the stage of the treatment. Generally speaking the therapy is started with a relatively low dose and in subsequent therapeutic sessions the dose is gradually incremented to a final, maximum value. This is indicated in more detail in the following table Table 1. Therein the first column indicates the skin type, the second column indicates the required starting dose for the first treatment, the third column indicates the value with which the dose is incremented at each therapeutic session and the last column indicates the maximum dose.

(24) TABLE-US-00001 TABLE 1 Recommended photon radiation dose for treatment of psoriasis Starting dose Increment Final Skin type (mJ/cm.sup.2) (mJ/cm.sup.2) (mJ/cm.sup.2) 1 300 100 2000 2 300 100 2000 3 500 100 2000 4 500 100 2000 5 800 150 5000 6 800 150 5000

(25) Depending on the circumstances a choice may be made whether the dose is to be provided in the form of a relatively short irradiation with a relatively high power density (e.g. for professional applications) or a relatively long irradiation with a relatively low power density (e.g. for home applications). For example, for a skin radiation apparatus for use at home it may be preferred to apply a relatively low power density. An apparatus for consumer applications may for example provide a line-shaped radiation pattern with a maximum power density of 10 mW/cm.sup.2 and may apply a dose of 300 mJ/cm.sup.2 in 30 s. For professional use by medically trained practitioners a line shaped radiation pattern having a significantly higher maximum power density may be applied allowing for a faster treatment, e.g. 50 mW/cm.sup.2 during 6 s or 300 mW/cm.sup.2 during 1 s.

(26) Irradiation with a particular duration may be achieved by a stepwise scanning of the area of the skin to be treated. For example the line shaped radiation pattern is stepwise displaced in the second direction with a stepsize s equal to the width of the radiation pattern each time the required radiation dose is reached. It is not necessary that the step size s with which the line shaped radiation pattern is displaced is equal to the width w of the pattern. The step size s may for example be a fraction of the width w, e.g. equal to half the width w. In this way a spatially relatively uniform radiation dose is reached also if the power density distribution in the second direction is relatively non-uniform, e.g. bell-shaped. When stepping with a step-size s each time interval t.sub.s, an average scanning speed v.sub.s equal to s/t.sub.s is obtained. It is not necessary that the required dose for a particular treatment session is applied in a single scan. Alternatively an accumulated dose may be obtained after a plurality of scans in a session, therewith enabling an intermittent application of radiation. This gives the medical practitioner more freedom in treatment algorithms. For example a dose of 300 mJ/cm.sup.2 is reached with 3 scans at a power density of 100 mW/cm.sup.2 and an exposure time of 1 s each.

(27) Instead of scanning step-wise, the line-shaped radiation pattern may be moved continuously with a velocity v.sub.c. In this case the average exposure time t.sub.exp is w/v.sub.c.

(28) The selection of the width w depends on the requirements of spatial accuracy with which the dose is to be controlled as well as the speed of treatment. A large width w is favorable for a fast treatment, however at the cost of a lower accuracy with respect to the spatial resolution. For practical purposes the width of the line shaped radiation pattern is for example in the range of 0.1 cm to 2 cm. If the width is larger than 2 cm, the spatial resolution with which the radiation can be applied to the surface of the skin becomes too low. A width smaller than 0.1 cm, although possible, would require relatively expensive optical means while not resulting in a more accurate treatment. Moreover, a small width would either require a relatively high power density, which may be dangerous in case of failure of the movement facility, or would result in long treatment times in case a lower power density is applied.

(29) It is noted that the dose to be applied may further be dependent on the severity of the skin disease.

(30) The embodiment of the apparatus shown in FIGS. 1A and 1B further comprises a movement detection unit 70 for generating a movement indication signal md, wherein the control unit 40 controls the power density distribution on the basis of the skin condition detected for the region and on the basis of the movement indication signal md. In this way the patient may move a bit while being treated. The movement detection unit 70 comprises for example an echo-doppler detector.

(31) FIGS. 2A and 2B shows an embodiment of the skin radiation apparatus that comprises an indication facility 50 for indicating the radiation power profile and/or the radiation dose profile of the radiation to be applied, as determined by the control unit, at the skin by means of moving a line-shaped radiation pattern. In the embodiment shown the indication facility 50 comprises a projector 52 that is capable of mapping a visible pattern 54 at the area of the skin to be treated. The visible pattern 54 is isomorphic with the required radiation power profile and/or the radiation dose profile as determined by the control unit 40. In the example shown in FIG. 2B, the patient 1 has two isolated regions 2a, 2b affected by psoriasis. It is noted that in practice the number of isolated regions may be significantly higher, e.g. hundreds to thousands of isolated affected regions may be formed on the skin. In the example shown the projected pattern 54 comprises two illuminated areas 54a, 54b that indicate the areas where the control unit 40 schedules radiation of the skin with therapeutic radiation. In this example the medical practitioner will observe that the illuminated area 54a coincides with the region 2a affected by psoriasis. However the practitioner also observes that one affected region 2b is not highlighted in the visible pattern. In this case the practitioner may apply a correction for example by indicating the contour of the affected region 2b with a pointing device and by giving a command to the controller 40 that this region should also be treated. To this end the controller 40 is coupled to a user interface 60 that serves as a feedback facility. The user interface 60 may comprise any means that is suitable to exchange information between the controller 40 and the practitioner, including for example a keyboard, a mouse, voice control, touch screen, dedicated control buttons, etc. The practitioner will also observe that the projected pattern 54 comprises a highlighted area 54b that is not affected by psoriasis. The practitioner may now point within this highlighted area 54b and give a command to the controller 40 that this area should not be treated. To indicate a position in a certain area, the user interface may for example comprise a tablet 61 and a pencil 62. The position indicated by the practitioner may be indicated by an arrow 63 that is projected onto the skin by the projection means 52. The practitioner may also indicate that the shape or power density or the dose of a highlighted area should be modified. The pattern 54 may be edited in way analogous to the way an image is photoshopped. In response to the commands given by the practitioner, the control unit 40 modifies the projected pattern 54 to indicate or to reflect the resulting radiation power profile or radiation power dose to be applied to the area to be treated.

(32) The apparatus shown in FIG. 2A, further comprises a learning unit 45 for teaching optimal operation of the detection unit 30 or controller 40, or both, on the basis of the proposed amendments to the radiation power profile and/or the radiation dose profile indicated by the operator/practitioner. The learning unit 45 may have means for selective activation. For example a password may be needed to restrict activation to experienced practitioners.

(33) FIG. 2C shows another embodiment, wherein the indication facility 50 comprises a display 56 that simultaneously shows an image of the area of the skin to be treated as well as a representation of the proposed radiation power distribution or the radiation dose distribution, e.g. by a color pattern, a pattern of intensity variations or a combination of both. Alternatively the display 56 may indicate the contours of the spots that are scheduled to be irradiated. The medical practitioner may indicate proposed amendments to the treatment in a way similar to that described with reference to FIGS. 2A and 2B. The practitioner may control various settings, e.g. the brightness and contrast with which the image of the area of the skin is displayed independent of the brightness and contrast with which the pattern 54 is displayed to obtain optimum visibility. Preferred settings may be stored, e.g. as default values. The display 56 may be a touch screen, so that the practitioner may indicate proposed amendments directly by pointing at the display 56.

(34) The skin radiation apparatus as shown in FIGS. 2A to 2C further comprises a storage facility 46 for storing data related to a therapeutic session. The data may comprise an image of the skin captured at the therapeutic session, e.g. at the beginning and/or at the end of the session, the applied radiation power profile, the applied radiation dose profile, amendments applied in the radiation power profile and/or the radiation dose profile etc. Data from multiple sessions related to a complete treatment program may be stored. The stored data may be used to analyze progress achieved with the treatment. The medical practitioner may use this information to control settings of the apparatus. An image recognition algorithm may also more rapidly classify the condition of the skin based on results obtained from previous sessions. In an embodiment the classification of skin conditions is based on a comparison of the results from the captured image of the skin with information from a database provided with the system. This database comprises e.g. data on the color appearance of skin in different states of inflammation. The storage facility 46 may be any non-volatile storage facility, such as a flash-memory or a hard-disk. Also a volatile storage facility could be used, but in the latter case a reliable permanently available power source is necessary. The system may comprise a network connection for consulting data, e.g. skin condition classification data, on remote data storage devices or knowledge databases.

(35) FIGS. 3A and 3B show an embodiment of the radiation apparatus wherein the detection unit 30, the photon radiation unit 10 and also the controller 40 are mounted in a common housing 5 that is movable by the movement facility 20, 22. The detection unit 30 is arranged to detect a skin condition in a line shaped area 36. Accordingly a full-fledged camera for imaging the skin to be treated is superfluous. Instead a linear camera, such as a CCD-camera can be used. It is also an advantage that only a modest amount of memory is required for storing the data indicative for the skin condition. In the embodiment shown the line shaped radiation pattern 12 is directed at the line shaped area 36. The movement facility 20, 22 is arranged to move the line shaped area 36 to a next position in the second direction y after subsequently the skin condition profile has been determined and the line-shaped radiation pattern has been applied to the line shaped area 36. In this way only a modest amount of memory space is necessary to store the skin condition profile and data indicative for the required radiation power profile, as this data can be immediately used by the control unit 40 for controlling the power density distribution of the line shaped radiation pattern.

(36) In case the medical practitioner first desires to observe the proposed radiation power profile and/or the radiation dose profile, the apparatus may make a full scan over the area to be treated and gather the required information about the skin condition of the patient, as well as the proposed treatment. Subsequently thereto the results may be shown on a display 56, e.g. a touch screen, and the medical practitioner may be enabled to amend the proposed radiation power profile and/or radiation dose profile by feedback means 60, 61, 62, in the same way as described with reference to the embodiment of FIG. 2C. During this full scan the photon radiation unit 10 may be disabled. The radiation power profile and/or radiation dose profile may be stored, so that for a subsequent treatment the medical practitioner can rapidly verify whether the radiation power profile and/or radiation dose profile to be applied are still suitable. Alternatively, when the detection unit 30 is capable of detecting the skin condition with sufficient reliability, feedback means and a display 50 may be superfluous. Accordingly in an embodiment the skin radiation apparatus does not have a feed-back facility and or an indication facility.

(37) FIGS. 4A to 4B shows a further embodiment. The apparatus according to this embodiment of the invention starts treatment with application of the line shaped radiation pattern 12 in a line shaped area 15 in the region for which the radiation power profile has already been determined, while the required radiation power profile is calculated for a subsequent positions 36 (FIG. 4B) in the second direction y. The movement facility (not shown) transports the housing 5 with the photon radiation unit 10 stepwise each time after a line shaped area 15 of the skin is irradiated. Therewith also the detection unit 30, arranged in the same housing 5 is transported to a next position. Alternatively, in another embodiment of the radiation apparatus the line shaped areas 15 and 36 may be adjacent areas wherein, during operation a first (first in the direction of movement by the moving facility, i.e. the second direction) line shaped area 36 is measured to determine the a skin condition profile while a second (subsequent to the first in the direction of movement by the moving facility, i.e. the second direction) line shaped area 15 is radiated with a power density distribution radiation pattern. After moving the movement facility in the second direction with an increment of one line shaped area width, a new first line shaped area 36 is presented for skin condition profile determination while the previous first line shaped area 36 now becomes the new second line shaped area 15 for photon radiation, and the previous second line shape area 15 has finished the photon radiation. These embodiments may operate faster than the embodiment described with FIGS. 3A and 3B because at least some of the steps related skin condition determination, radiation power density calculation and applying the photon radiation may be executed concurrently instead of sequentially.

(38) It is not necessary that the housing 5 with the photon radiation unit 10 is moved stepwise. Alternatively the photon radiation unit 10 may be moved continuously while irradiating. The apparatus may have an interpolation facility 42 to interpolate the power density distribution for the line-shaped radiation pattern 12 between subsequent positions in the second direction y. Alternatively, the control unit 40 may stepwise change the power density distribution in the line-shaped radiation pattern each time the movement has proceeded over a predetermined distance in the second direction y.

(39) The administered photon radiation dose is proportional to the line width w divided by the movement speed v. This is either the continuous speed or the average speed resulting from the stepping process, which is s/t.sub.s, wherein s is the step-size and t.sub.s is the time interval between subsequent steps.

(40) The available time for detecting the skin condition and calculating the required radiation power profile is d/v, wherein d is the distance between the line shaped region 36 for which the skin condition is detected and the line shaped region 15 that is treated with radiation.

(41) FIGS. 5A to 5C shows photon radiation units 10 for various embodiments of the apparatus. In the embodiment shown in FIG. 5A, the radiation source 14 is a laser, for example an excimer laser having a wavelength of 308 nm. The photon radiation unit 10 comprises apart from the radiation source 14, a plurality of rotatable mirrors 142a to 142c. Although only 3 rotatable mirrors are shown for clarity, in practice a substantially larger amount of mirrors may be used. The photon radiation unit 10 further comprises a driver 140 that controls the plurality of rotatable mirrors 142a,b,c. The rotatable mirrors 142a,b,c are controllable in a first orientation (as shown for mirror 142a) wherein they reflect photon radiation from the photon radiation source 14 towards the line shaped area and a second orientation (as shown for mirrors 142b, c) wherein the photon radiation can pass along the mirror. A desired radiation dose distribution within the line shaped region can be obtained by subsequently rotating the mirrors in the first orientation for a time proportional to the desired radiation dose. Alternatively the radiation power and therewith the radiation dose may be controlled by regulating the power of the laser 14. These two ways of control may be combined.

(42) FIG. 5B shows a second embodiment, wherein the power of the laser 14 is modulated by a laser driver 144, controlled by the controller 40. The laser beam emitted by the laser 14 is directed towards a rotating hexagonal mirror 146, that reflects the radiation of the laser 14 towards a position within the line shaped area 12 that is to be irradiated.

(43) In the embodiment of FIG. 5C, the photon radiation source 14 comprises a plurality of radiation source elements 14a, . . . , 14x, such as for example light emitting diodes (LED), that are each capable of radiating a respective portion within the line shape area of the skin. The photon radiation source 14 is controlled by a driver 148 that is on its turn controlled by the controller 40.

(44) Arithmetical and logical operations carried out by various parts of the apparatus of the control unit 40, by the detection unit 30, and the drivers 140, 144 or 148 may be carried out by dedicated hardware, by software in a programmable processors or by a combination of both.

(45) Although the apparatus and method described above have been described particularly with reference to the treatment of psoriasis, the apparatus and method can alternatively be modified to be suitable for the recognition and treatment of other skin conditions, such as myocosis fungoides, eczema, actinic keratosis, lichen planus etc. For treatment of other skin conditions than psoriasis, other photon radiation wavelengths, wavelength ranges or combinations may be used.

(46) In the claims the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. A single component or other unit may fulfill the functions of several items recited in the claims.

(47) The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope. Further, unless expressly stated to the contrary, or refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).