Surgery – Instruments – Light application
Reexamination Certificate
1999-09-28
2002-05-07
Shay, David M. (Department: 3739)
Surgery
Instruments
Light application
C606S010000, C606S013000, C606S015000, C607S089000
Reexamination Certificate
active
06383175
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a medical laser apparatus to be used as a light source for a diagnostic/treatment apparatus which treats a focus of a tumor such as a cancer or the like through irradiation of light to the focus. When light having a wavelength coinciding with the absorption wavelength of a photosensitizer which has an affinity to the focus and has been preliminarily accumulated in the focus is irradiated to the focus, the photosensitizer is excited, making it possible to diagnose or treat the focus. The present invention relates alike to a diagnostic/treatment apparatus using the medical laser apparatus.
In accordance with the development of electronic medical-care technology, photodynamic diagnosis (referred to as PDD hereinbelow) and the photodynamic therapy (referred to as PDT hereinafter), each utilizing laser light, have made rapid progress recently. In PDD and PDT, a photosensitizer having affinity to a tumor and capable of a photochemical reaction, e.g., an emission of fluorescence or a cellcidal action, is accumulated in a focus of the tumor beforehand, and then light is irradiated to the focus, which induces the excitation of the photosensitizer, to thereby permit diagnosis of the focus by measuring the emitted fluorescence (PDD) or treatment of the focus by the cellcidal action (PDT). It is preferable that the wavelength of the light irradiated to the focus coincides with the absorption wavelength of the photosensitizer in order to efficiently excite the photosensitizer, and therefore a laser light source has been generally employed as a light source of the light irradiating to the focus. In this case, the laser light source is fitted to the absorption wavelength of the photosensitizer being used.
A dye laser which uses hematoporphyrin as a photosensitizer and an excimer laser as a laser light source (referred to as an excimer dye laser hereinbelow) has been often used in the above-described type of diagnostic/treatment apparatus for diagnosing and treating cancers, as is discussed in Japanese Patent Publication Nos. 63-2633 (2633/1988) and 63-9464 (9464/1988). The conventional diagnostic/treatment apparatus using the laser device disclosed in the noted publications will be described with reference to FIG.
4
.
FIG. 4
schematically shows the constitution of a cancer diagnostic/treatment apparatus using a conventional laser apparatus. In
FIG. 4
, A is a focus of a cancer and B indicates the peripheral part of the focus A where hematopor-phyrin has been absorbed as-a photosensitizer beforehand. A first pulse source
31
for diagnostic purposes and a second pulse source
32
for treatment purposes are both constituted of an excimer dye laser. An excimer dye laser for exciting the first and second dye lasers
31
,
32
repeatedly oscillates with an oscillating wavelength 308 nm and pulse width 30 ns while varying the energy in the range of several mJ-100 mJ. The oscillating wavelength of the first pulse source
31
is 405 nm and that of the second pulse source
32
is 630 nm. The first and second pulse sources
31
,
32
are switched by a switching part
33
. The other reference numerals represent:
34
a light transmission line;
35
a TV camera;
36
a TV monitor;
37
a half mirror;
38
a spectroscope;
39
a spectrum analyzing part; and
40
a display unit.
The diagnosing/curing apparatus of the above-described constitution operates as follows.
When a cancer is to be diagnosed, a laser light of the wavelength 405 nm generated from the first pulse light source
31
is irradiated to the focus A and the peripheral part B through the switching part
33
and the light transmission line
34
. A fluorescence image of the wavelength 630 nm, 690 nm excited by the laser light of 405 nm wavelength is photographed by the TV camera
35
and displayed for observation on the. screen of the TV monitor
36
. At the same time, the fluorescence image is extracted by the half mirror
37
and divided by the spectroscope
38
. The spectrum is analyzed in the spectrum analyzing part
39
and the wavelength of the spectrum is displayed by the display unit
40
. In order to treat the cancer, then, a laser light of the wavelength 630 nm produced by the second pulse light source
32
is, through the switching part
33
and the light transmission line
34
, irradiated to the focus A. The operation mode is subsequently switched to the diagnosing mode again to thereby confirm the result of the treatment. The cancer is diagnosed and treated by repeatedly switching the modes as above.
In addition to the fact that the fluorescence peculiar to hematoporphyrin is efficiently excited by the light of the wavelength 405 nm, adverse influences resulting from scattering light can also be restricted due to the difference of the wavelengths 630 nm and 690 nm of the fluorescence, the first pulse light source
31
for diagnostic purposes thus uses the wavelength 405 nm. Meanwhile, the second pulse light source
32
for treatment purposes is set at the wavelength 630 nm because the laser light of the wavelength 630 nm transmits well through the tissue and is efficiently absorbed in hematoporphyrin.
In addition to the aforementioned example, the photosensitizers in (Table 1) below are proposed for use in PDD and PDT and also the lasers shown in (Table 1) are tried to be used as a laser light source for PDT.
TABLE 1
Absorp-
tion
Laser light
Photo-
wave-
source (projec-
sensi-
length
tion wavelength
Disadvantages of
tizer
[nm]
[nm])
laser devices
HpD
630
Excimer dye
*Deterioration
laser
of solution of
Argon dye laser
coloring matter
(624 ± 6.5 nm)
is fast
*Bulky and
expensive
Gold vapor laser
*Necessary to
(627.8 nm)
warm up for 30
min. or more
*Life of gas and
oscillating
tube is short
*Bulky and
expensive.
PH-
650
Krypton laser
*Life of gas is
1126
(647 nm)
short
*Bulky and
expensive
NPe6
664
Argon dye laser
*Deterioration
(667 ± 5 nm)
of solution of
coloring matter
is fast
*Bulky and
expensive
A drawback of the conventional diagnostic/treatment apparatus of cancers resides in the fact that the wavelength of the projected laser light is difficult to control.
In other words, it is necessary to make the wavelength of the laser light coincides with the absorption band of the photosensitizer so as to efficiently excite the photosensitizer. Generally, it is not possible for the gas laser (Table 1) to meet the absorption band of a plurality of the photosensitizers. Moreover, it is difficult for the gas laser to have a wavelength which coincides with the maximum absorption wavelength of even a single photosensitizer. Although a dye laser as depicted with reference to the above conventional example has been employed to solve the problem, it is necessary to exchange the solution of a coloring matter in order to change the oscillating wavelength of the dye laser. Therefore, a plurality of dye lasers corresponding to a plurality of different kinds of solutions of a coloring matter should be prepared and exchanged for every wavelength if the wavelength of the laser light is required to be changed, for instance, when the photosensitizer being used is changed or when the wavelength of the laser light is changed during treatment relative to that used during diagnoses.
In the case where the dye laser is used, therefore, the diagnostic/treatment apparatus becomes disadvantageously bulky in size to accommodate a plurality of different kinds of coloring matter solutions and a switching of the solutions.
A second disadvantage of the diagnostic/treatment apparatus using the dye laser is that the solution of a coloring matter of the dye laser easily deteriorates, inviting a change of the wavelength of the resultant laser light or a decrease of the output. Since the safety of the laser light is an essential and indispensable condition to ensure the effect of PDD and especially PDT, a substantial problem of the dye laser arises when the solution of the coloring matter should be exchanged or a circulator of the coloring matter should be cleaned frequently.
Aizawa Katsuo
Ii Yoshiteru
Kaneda Akira
Kato Harubumi
Yamamoto Toshiyoshi
Matsushita Electric - Industrial Co., Ltd.
Shay David M.
Wenderoth , Lind & Ponack, L.L.P.
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