Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/06—Radiation therapy using light
  • A61N5/0613—Apparatus adapted for a specific treatment
  • A61N5/062—Photodynamic therapy, i.e. excitation of an agent
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N2005/002—Cooling systems
  • A61N2005/005—Cooling systems for cooling the radiator
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/06—Radiation therapy using light
  • A61N2005/0635—Radiation therapy using light characterised by the body area to be irradiated
  • A61N2005/0643—Applicators, probes irradiating specific body areas in close proximity
  • A61N2005/0644—Handheld applicators
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
  • A61N5/00—Radiation therapy
  • A61N5/06—Radiation therapy using light
  • A61N2005/065—Light sources therefor
  • A61N2005/0651—Diodes
  • A61N2005/0652—Arrays of diodes

Definitions

• photosensitizing drugs such as hematoporphyrin derivatives are introduced into and retained by the hyperproliferating cells or tissue such as cancerous tissue and atheromas. With the exposure to suitable wavelengths of light the photochemical reaction of the photosensitizer can lead to selective destruction of photosensitizer-associated cells or tissue.
• PDT also holds potential for a number of possible applications other than cancer treatment such as for treating microvascular lesions and blood purging.
• a Light Emitting Diode is a solid state electronic device capable of emitting light when an electric current is passed through the device.
• LED-derived light is relatively broad band (20-40nm) and is emitted in a wide output distribution pattern, and lacks coherence. The light is produced at very low current levels (20ma) . All of these characteristics of LEDs serve to technically differentiate them from laser diodes.
• the major advantage gained by using a laser for PDT is the ability to couple significant light power into flexible optical waveguides. This is necessary for applications requiring interstitial or endoscopic delivery of treatment light for PDT. Laser diode systems which include a large power supply and cooling system are very expensive. There are a significant number of applications for PDT that do not require the use of a laser light source or the delivery of light through light guides.
• non-laser light sources there is truly a need for a low cost non-laser light source for use in PDT.
• the major properties of these light sources that determine their applicability in PDT are: .a) output spectrum; b) brightness or intensity at a suitable wavelength; c) deliverability; d) size; and e) cost.
• These non-laser light sources include arc lamps, incandescent lamps, fluorescent lamps and light emitting diodes (LEDs) .
• the lamp sources have a broad emission spectrum ranging from ultraviolet to infrared.
• LED technology unlike the other non-laser light source outlined above, has the advantage of small size, typically 0.3 mm by 0.3 mm, limited emission spectrum band, typically 20 nm to 40 nm, high efficiency and low cost.
• the light power emitted from a single diode is relatively low however (approximately 4 milliwatts to 5 milliwatts for the brightest red LEDs using the specified driving currents) but its emission angle is low when compared, for example, to the arc lamp so that its actual brightness is reasonably good.
• the small size of the LED along with its high efficiency give the potential of using an array consisting of multiple LEDs in a single device to significantly increase deliverable power density over a large area.
• the low power output has, however, delayed the acceptance of LED arrays as a suitable light source for PDT.
• the intensity can be increased by over- driving the LEDs in the array. Such over-driving results in heating which shortens the lifetime of the LED and causes a spectral shift in the output.
• LEDs are available in variety of discrete packages as well as several one and two-dimensional array packages. As used herein, an LED array means multiple LED's integrally mounted in a single device. Commercially available arrays, from manufacturers such as Mitsubishi, Hewlett Packard or Stanley Electric, combine a few LEDs in a single package but not in high enough packing density or in geometries suitable for PDT.
• None of these prior art devices can provide sufficient power density for effective PDT treatments, nor can they be easily configured in the geometries necessary for the wide range of applications for surface illumination and PDT. It is desirable to have a multiple integrated LED array with a power output suitable for use in PDT.
• SUMMARY OF THE INVENTION It is an object of this invention to provide an array of multiple integrated LEDs useful for photodynamic therapy. It is another object of the invention to provide an inexpensive light source useful for photodynamic therapy. It is still another object of this invention to be able to provide an LED array for photodynamic therapy that is capable of illuminating the surface of various types of tissues. It is yet a further object of this invention to provide an LED array for photodynamic therapy which enables accurate wavelength and exposure control and permits accurate dosimetry.
• the LED light source of the present invention is novel because it teaches how to use the characteristics of the LED to an advantage over the laser diode for applications of PDT which do not require interstitial or endoscopic light delivery.
• the wide output distribution pattern, small size, and minimal cooling requirements of the LED allow large arrays of the devices to be constructed which cumulatively are capable of producing a total output light power exceeding that of laser diodes. This opens up applications for large surface area illumination (such as is needed in dermatology) for which laser diode systems are inadequate.
• Figure 1 is a schematic representation of an LED system suitable for illumination of surfaces for photodynamic therapy.
• Figure 2 schematic diagram of the front panel of the LED
• Figure 4 is a top view of the LED puck configured for
• Figure 6 is a cross-sectional view of the LED handpiece
• Figure 7 shows the LED sleeve for cylindrical surface
• Figure 8 is a schematic diagram of a preferred embodiment
• the shape may be circular, rectangular (or
• Planar arrays of LED's may # 25 be bent or folded to form various curvilinear surfaces to conform
• the LED's must be
• FIG. 1 we see a schematic view of the LED system configured for flat surface illumination and generally indicated at the numeral 10.
• the system consists of the LED array driver 11, the flat surfaced LED handpiece 12, the flat surfaced LED puck 13 and the closed loop chiller 14.
• the detailed controls of the front panel of the system are shown in Figure 2 of the array driver 11, and shows the displays for the controls of exposure 21, power 22, the coolant temperature display 23 and the power supply 24.
• An LED handpiece configured for flat surface illumination 12 is shown in cross section in Figure 3.
• the stainless steel housing 31 and threaded retaining ring 32 are connected to the system ground 33 and provide one electrical connection to the LED puck 13.
• the heat sink 34 is connected to the LED supply voltage 35. This provides the second electrical connections to the LED puck as well as removing the heat generated in the puck.
• the heat sink is electrically insulated from the housing by the DELRIN® insulator 36.
• the coolant tubes 37 provide a flow of cooling water from the chiller to the heat sink.
• the light output power and wavelength detector 38 (shown in greater detail in Figure 8) detects the amount of light being delivered to the patient by sensing the light through the light sense channel 39.
• An LED puck configured for flat surface illumination is shown in Figure 4.
• the puck, generally indicated at 13 comprises a gold plated insulated copper and fiberglass laminate sheet 41 bonded to a flat copper substrate 42. Holes are machined through 1 the copper laminate to the surface of the copper substrate.
• the insulator 36 function the same as in the flat surface
• Figure 7 shows an LED sleeve configured for cylindrical
• the LED array is mounted on a puck enabling the LED array to be cooled to control the bandwidth and wavelength of the output light and increase the lifetime of the array.
• the output wavelength depends on the diode's junction temperature. Monitoring the wavelength permits adjustment of the coolant temperature and flow rate to maintain the junction at the desired temperature.
• the foregoing preferred embodiment of the LED system for photodynamic therapy provides a low cost, high power excitation source for PDT which can be produced in a variety of shapes used in a wide variety of applications.
• This device will allow PDT to become viable treatment modality for many more cancer patients inasmuch as it will now be cost effective for the physician's office or small clinic.
• single LED chips may be fabricated into an array by depositing them directly onto a chilled substrate by techniques currently used in hybrid circuit fabrication. Accordingly, it is to be understood that the drawings and descriptions herein are preferred by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

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• Health & Medical Sciences (AREA)
• Biomedical Technology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Pathology (AREA)
• Biophysics (AREA)
• Radiology & Medical Imaging (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Radiation-Therapy Devices (AREA)

Applications Claiming Priority (3)

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• 1994
  • 1994-01-12 EP EP94906636A patent/EP0680361A4/fr not_active Ceased
  • 1994-01-12 AU AU60284/94A patent/AU681376B2/en not_active Ceased
  • 1994-01-12 CA CA002153337A patent/CA2153337C/fr not_active Expired - Fee Related
  • 1994-01-12 WO PCT/US1994/000506 patent/WO1994015666A1/fr not_active Ceased

Patent Citations (3)

Non-Patent Citations (1)

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