Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-03-14
2003-10-28
Smith, Ruth S. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S109000, C600S178000, C607S088000
Reexamination Certificate
active
06640131
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for the “in vivo” diagnosis by means of a light-induced reaction created by an endogenous or exogenous photo-amboceptor.
In order to trigger a light-induced reaction in biologic systems a photo-amboceptor is administered to the patient in a concentration of a few mg/kg body weight.
PRIOR ART
Typical photo-amboceptors or sensitisers are Photofrin or Photosan, which present a basic hemato-porphyrin framework structure, protoporphyrin IX induced by &dgr;-amino-laevulic acid (ALA) (PPIX), which has been used in urology and dermatology for a short time, 9-Oac-tetramethoxy porphycene, benzoporphyrin derivatives, as-partyl chlorine E
6
, m-tetrahydroxyphenyl chlorine, Sn(IV) etiopurpurine or Zn(II) phthalocyanine.
These substances accumulate in tumour tissues in a concentration increased by roughly two to fifteen times. This selective concentration in tumour tissue is the decisive basis of the photodynamic diaghosis (PDD) and photodynamic therapy (PDT).
For diagnosis the tissue to be analysed is irradiated after an appropriate waiting period following the administration of the photo-amboceptor, with blue or violet light—in known devices with laser light almost exclusively. The photo-amboceptor, which is present in an increased concentration in tumour tissue, is excited by this light and displays in response a typical red fluorescence by which the tumour can be localized.
Apart from fluorescence—which is produced by a photo-amboceptor accumulated in the tissue—the so-called autofluorescence of the tissue may be triggered, too, which is brought about by endogenous fluorescent pigments. In this case mostly blue or ultraviolet light is used for excitation as well.
In dependence on the respective photo-amboceptors used, the photodynamic diagnosis (PDD) entails certain problems. When photofrin and photosan-3 are used as photo-amboceptors in photodynamic diagnosis highly complex engineering devices are required for the detection of fluorescence because, on account of interfering autofluorescence fractions, only very complex computer-assisted image processing techniques and highly sensitive cameras with residual-light intensifier are suitable for an appropriate detection of the fluorescence in tumor tissue.
When &dgr;-aminolaevulic acid (ALA) is used the induced fluorescence is strong enough for recognition merely by visual inspection.
However, the fluorescence achieved by means of &dgr;-aminolaevulic acid does not furnish an optimum quality of the image which is to be recorded as part of the diagnosis. This is due, inter alia, to variabilities of the optical tissue parameters which take an influence on the fluorescent intensity in a non-specific manner.
It is moreover known to use photo-amboceptors for photodynamic therapy (PDT). In this respect reference is made to the document WO 93/20810, which is, by the way, also referred to explicitly with respect to the explanation of all terms and steps of operation which are not described here in more details.
The devices used for photodynamic diagnosis—which is also referred to as fluorescent diagnosis—or for photodynamic therapy, respectively, which are also termed “PDD” or “PDT” devices, comprise an illuminating system, a light-feeding unit which directs the light from the illuminating unit to the tissue region to be diagnosed and/or treated, and an imaging, an image-recording and possibly an image-transmitting unit which images the light coming from the tissue region into a proximal image plane.
The illuminating system and the light-supplying unit define the path of the illuminating beam whilst the imaging, the image-recording and possibly the image-transmitting unit define the path of the observation beam.
In an endoscopic PDD device the light-supplying unit consists of the light guide, which connects the illuminating system to the light guide connector of the endoscope, for instance, and the illuminating light guide of the endoscope. The light guide may be a quartz light guide or a fluid light guide, for instance. Fluid or quartz light guides offer a better transmission in the blue or violet range than standard glass light guides. The endoscope lens, which is disposed on the distal end and covers the tissue range illuminated by the light emerging from the illuminating light guide, constitutes the image-recording unit; the image of the lens is picked up, for instance, by means of one or several CCD receivers which serve as opto-electronic image converter unit. When the CCD receiver is disposed on the proximal end the lens image is transmitted by a relay lens system or an imaging fiber bundle which hence fulfill the function of the image-transmitting unit.
In the PCT application PCT/DE 96/01831, which is not a prior publication, it has been proposed to perform endoscopic photodynamic diagnosis and therapy by means of an apparatus in which a “source of white light” is used as light source rather than a laser, i.e. a light source which generates incoherent light in the wavelength range of at least from 390 to 650 nm. The light from the light source is fed via a focusing unit into the fiber optic light guide.
The aforementioned application contains moreover the proposal to harmonize the spectral internal transmittance factor or the (spectral) transmission function, respectively, of the light-feeding unit with the spectral internal transmittance factor or the (spectral function), respectively, of the imaging or image-recording unit in such a way that only a fraction of the light reflected on the irradiated tissue contributes to the production of the image, which is so dimensioned that the fluorescent image will not be glared or blanketed by this “background picture”.
Filter systems are used, as a rule, to set the transmission function. The filter systems so far proposed entail the disadvantage, however, that small errors due to tolerances are sufficient to result in major variations of the reflected light quantity which contributes to the production of the image, which errors occur particularly in terms of the edge position and the steepness of the transmission edge. This effect, in its turn, results in a major change of the ratio between the fluorescent light and the background light.
When, for instance, the filter graph of the filter system introduced into the path of the illuminating beam is shifted towards shorter wavelengths as a result of manufacturing or assembly faults—tilting of the filter, etc.—the overlapping of the transmission zones of the filter systems introduced into the paths of the illuminating and observation beams is practically reduced to “zero” in the event of small shifts already so that a background image is not obtained as a result of the directly reflected light and only a fluorescent image is achieved.
Vice versa, with a small shift towards longer wavelengths already an excessive overlapping is achieved so that the fluorescent image is blanketed by the visible (“non”-fluorescent) background picture.
Moreover, a variation of the steepness of the transmission edge also displaces the position of the transmission graph in the lower transmission range so that this error requires compensation like an edge position error. In the upper range the overall transmission is, as a matter of fact, subjected only to a slight change.
Similar problems occur also in devices where a photodynamic diagnosis is performed by means of a microscope and particularly a surgical microscope. Appropriate devices are described in the European Patent EP 0 241 268 A1 or the U.S. Pat. No. 5,371,624.
The problems which may occur in filter selection are described also in the U.S. Pat. No. 4,056,724—cf. FIG. 14 in particular.
In all other respects explicit reference is made to these prior art documents as far as the explanation of all terms is concerned which are not described here in details.
BRIEF DESCRIPTION OF THE INVENTION
The present invention is based on the problem of proposing a spectral internal transmittance characteristic or a transmission function for the path of the illuminati
Erhardt André
Irion Klaus M.
Stepp Herbert
Tafelmaier Hans
Karl Storz GmbH & Co. KG
Smith Ruth S.
St. Onge Steward Johnson & Reens LLC
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