CA2444413A1

CA2444413A1 - Violet laser induced fluorescence for cancer diagnosis

Info

Publication number: CA2444413A1
Application number: CA 2444413
Authority: CA
Inventors: Thomas H. Pearce
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-10-09
Filing date: 2003-10-09
Publication date: 2005-04-09

Abstract

This invention is a process and a method to visually identify and delineate, areas of interest or utility in samples for medical, biological or other natural scientific reasons, by observing fluorescence, autofluorescence, phosphorescence and the like, excited in the sample by violet laser light. Imaging is accomplished by using a special filter matched to exclude the laser wavelength. The new technology of violet laser diodes is used in order to produce a lightweight, low power, portable, device which permits real time observation of medical and other natural subjects at an economical cost. More especially, said invention relates to the use of such a device to visually identify and delineate breast cancer in vivo, during surgery or in a pathology laboratory.

Description

VIOLET LASER INDUCED FLUORESCENCE FOR CANCER DIAGNOSIS
This invention provides an economical, portable, device which can produce images (visible by eye and recorded) of violet laser induced fluorescence on natural materials more especially breast cancer.
During surgery, the use of laser fluorescence helps to determine the extent of the malignancy, while the recording unit preserves images of the actual operation.
BACKGROUND OF THE INVENTION
Cancer is one of the major diseases of modern societies and, in particular, breast cancer is the leading cause of death among women in North America. About 1 in 8 women in the United States and Canada will develop breast cancer. In 2003, 211,300 new cases of breast cancer will be found and 39,800 men and women will be lost to this disease in the United States alone. Because surgery is the first treatment for breast cancer, such surgery is the most common type of surgical procedure in Cancer Clinics.
It has been known for some considerable time that cancer cells fluoresce a different colour than normal cells of the same type. However, fluorescence has not been effectively used as real time aid in surgical procedures. It is also suspected that certain types of pre-cancerous tissue may possess a characteristic fluorescent colour. In addition, different types of normal tissue not known to be diseased can also have a variable fluorescence signature. Also, the same disease may present in different patients with different characteristics. Obviously, the more information that surgeons and pathologists and the like have immediately at their disposal, the more rapid and accurate will be the diagnosis and the less will be the discomfort for the patient. It is axiomatic that rapid treatment increases the survival rate. The present invention is designed to address these concerns.
PRIOR ART
Other inventions have dealt with similar problems (but generally not specifically breast cancer) by using spectrometry, computers, compound optical trains, etc. Existing inventions have technical problems common in this field such as high cost (estimated to be in the range of $100,000 to $500,000), complexity of design, difficulty of use (combinations of spectrometry, video imaging) and a lack of ruggedness and portability. In particular, surgeons and pathologists may not be familiar with computerized digital spectroscopy and it may not be appropriate to place such equipment in operating theaters. In cases where ultraviolet light is used to illuminate the sample to be examined, there is also an inherent safety problem as ultraviolet light is dangerous to the human eye. Safety is seldom discussed in any of the patents in this field.
U. S. Pat. 6393315 May 21, 2002 Aprahamian, P. M., et al.
This invention requires two light sources. "Luminous excitation is preferably constituted by two wavelengths or two spectral bands, namely one of about 590 nm or centered on 590 nm and adapted to excite the porphyrins, and the other of about 400 nm or centered on 400 nm (or if desired about 355 nm), adapted to excite other endogenous chromophores". The method requires acquiring, for the same tissues to be analyzed, fluorescence signals in the "spectral bands centered, respectively, on about 600 nm (or else about 680 nm) and on about 630 nrn andlor 680-690 nm, and, as the case may be, on about 470 nm and/or 510-520 nm, for each of the points to be measured".
None of figures relate to human patients and there is no provision for real time imaging or portability. The figured spectra are different from the spectra collect in this work using Violet Laser Excitation.
U.S. Pat. 5,467,767 Nov. 29, 1995 Alfano, R. R., et al.
In one embodiment, the method comprises irradiating a human breast tissue sample with light at a wavelength of about 310 nm (Ultra Violet) and measuring the time-resolved fluorescence emitted therefrom at about 340 nm. The time-resolved fluorescence profile is then compared to similar profiles obtained from known malignant and non-malignant human breast tissues.
This invention has a similar objective to the present invention but used a different method U.S. Pat. 5381224 Jan. 10, 1995 Dixon, A. E., et al.
This invention relates to the field of Scanning Laser Imaging Systems when used to image macroscopic specimens. The diagrams show a quite complicated conoscopic device which is likely to be quite expensive to manufacture. There are no photos produced by the device and fluorescence is mentioned in passing and apparently requires a *theta laser scan lens.
There is no provision for portability.
U.S. Pat. 6584342 Jan. 24, 2003Trushin et al.
Tissue is irradiated with low intensity monochrome radiation in the wave length band of 630 to 645 nm and the fluorescent image is recorded within the band of 650 to 730 nm.
This is a complicated device based on different technology than the present invention and which is not portable and is likely to be quite expensive to manufacture.
SUMMARY OF THE INVENTION
The object of this invention is to provide an economical, portable, device which can provide images (visible by eye and recorded) of violet laser induced fluorescence on natural materials. Specimen include but are not limited to: biological or medical samples which are useful for diagnosis and study of various diseases, or more especially breast cancer. The invention provides real time imaging in a portable unit and can have a sterile cover for use in operating theaters or pathology laboratories. The use of violet laser light provides a safety feature while maximizing the visible luminescent effect of the laser as explained in the description below. Violet Laser Induced Fluorescence of human breast tissue from known cancer patients yields fluorescent peaks at about 510, 560, and 590 nm).

FIGURE 1 is a schematic representation of the present invention with the parts described below:
1 ) Laser, 404 + 2 nm (violet) 2) beam expander/scanner + filters 3) filters (laser blocking, visible transmission) 4) coupler for real time observation by eye 5) coupler to allow analysis of light other than by imaging 6) focusing imaging device, (6 or 7 or 8 can have a method to view the image before permanently saving the image) 7) recording medium for imaging device 6 8) device to transport or transmit images or other information 9) computer for analysis and enhancement 10) ancillary equipment such as optical spectrometer and the like 11 ) the specimen (such as a cancer tumour) lies within the elliptical area illuminated by the Laser scanner device DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 is a schematic diagram of the device for certain embodiments of the present invention. The laser 1 outputs 404 + 2 nm, more or less, of violet radiation. The output is then expanded by 2 into a broad beam sufficient to illuminate the sample 11. Said beam expander 2 can use lenses, or a scanning raster, or both, to expand the beam in an adjustable manner to illuminate the sample area.
The sample 11, which may be observed during and after surgery, is illuminated by the Laser Illumination Unit, LIU (1, 2). The laser working distance between LIU and 11 is variable (from as little as 0.1 m tb as much as several meters) using an attachment system which is suited to the environment of observation (for an operating room, all equipment must be sterile).. The angle between the axis of laser illumination and the axis of the visualizing unit is similarly variable in two dimensions. Thus the geometry of the total device may be adjusted in 3 dimensions to fit the geometry and safety considerations of the environment in which the observations are made. For use in operating theaters and the like, the laser unit LIU is covered by a sterile covering which can be disposable. It is understood that in some cases it might be advantageous to add a filter or filters to the laser to shape the wavelength output of the laser.
The observations of the fluorescence emitted by the sample are made using the Visualization and Recording Unit (VRU), 3,4,5,6,7, 8, 9. Items 3,4,6,7, 8 together, form a recording macroscope with real time imaging. The filter unit 3 comprises at least one filter matched to the laser so as to block the laser illumination but which passes the rest of the visible light spectrum produced by fluorescence in the sample. Other filters in 3 can reduce overall intensity and/or enhance certain colored effects by selectively blocking certain bands within the visible light spectrum. The working distance between 11 and VRU (3cm to lm, more or less) is adjustable in 3 dimensions (by attachment not shown in Fig. 1). Said adjustment is made to suit the sample and the environment in which the observations are being made. In most cases, the environment must be darkened in order to see or record the fluorescence. The visualization unit VRU contains a coupling units in 4 and 7 which permit light to form an image for the eye (dashed line and eye-symbols in Fig. 1). The light can also be outputted via a coupling unit 5 to a device 10 for further analysis such as by a spectrometer or the like. Imaging for recording is performed by 6, an imaging device which can be a simple as an adjustable lens. The image is recorded on 7 using a recording medium such as film, ccd, video tape, video or the like, depending on the application.

The observations may be transported to other equipment for fwrther work by a transport or transmitting device 8 which can be as simple as a "memory stick". Further analysis and/or enhancement (not generally in real time) can be performed by 9, a computing device. Equipment 10 for further analytical work, such as a spectrometer and the like, is coupled optically to 5 and electronically to 8 and 9. Device 7 can have a method to view the image before permanently saving the image for example on high-density digital storage devices (7, and within 9). For use in operating theaters and the like, the Visualization Recording Unit, VRU (items 3 to 10) is covered by a sterile covering which can be disposable.
It is understood that power supplies, lightweight batteries, or the like, are included in parts 1,6,8,9, and 14 where needed. As laser diodes are extremely susceptible to adverse heating effects, it is taken as given that the laser 1 has a cooling apparatus including thermal sensing device, and switching circuit to prevent destruction by overheating. It is further understood that since the sample is illuminated by a broad laser beam, therefore, everyone present in the room (or the location) in which the fluorescent observations are taking place must wear safety glasses of a type matched to block the wavelength of the laser. Said safety glasses are provided for that use with the invention.
Violet laser light is essential to this invention for a number of reasons.
Both ultraviolet (UV), and violet light are dangerous to the eye and both are capable of inducing fluorescence. However, UV is invisible to the eye. If the eye is exposed to UV light damage can be done to the eye without anything being seen or even felt (as there are no pain receptors in the eye, it has no feeling of pain).
In contrast, the eye sees any stray violet light, for example, due to specular reflection or focusing by drops of fluid, as uncomfortably bright. The eye tends to be naturally averted from bright points of laser light. This phenomenon results in a built-in safety feature of the present invention. Violet laser light can be seen and cause the eye to look away before the accidental exposure does any damage.
In addition, experiments done by the inventor have shown that the fluorescent signature produced by laser light is sharper and less noisy compared with UV light sources.
Therefore the violet laser is a superior excitation source for the purposes of this invention. The fluorescent effect produced by this invention is different than that produced by UV, or visible light such as blue (442 nm).

The new laser diodes are small, light; powerful, and have a nominal 10,000 hour lifetime. They do not require plasma tubes and require about 3 to 5 volts electrical potential.
This new technology relaxes design criteria when making an embodiment of this invention, resulting in designs which would not have been practicable even a few years ago. The equipment can be battery powered and completely portable; in some embodiments, its use is not even limited to the surface of the earth.
In one practice, the device would be used in an operating room by a surgeon during an operation to remove a tumor. When the surgeon wishes to examine the texture or structure of the material surrounding a tumor he can dim or extinguish the room lights and simultaneous turn on the Laser Illumination Unit. The laser unit illuminates the tumor and surrounding tissue causing auto-fluorescence. Because the tumor and surrounding normal tissue fluoresce different colors and tend to have different textures and structures, the margins of the tumors can be visually enhanced by comparing the white-light and fluorescent images. Thus the use of laser fluorescence helps to determine the extent of the malignancy, while the recording unit preserves images of the actual operation. After surgery, but before fixing the tissue in formaldehyde, the pathologist can examine the tumor sample in detail using fluorescence and white light while he is preparing his report. Also, the pathology observations can be recorded and compared with the results fram the surgery.

Claims

1. This invention relates to a portable device for examining and recording violet laser induced fluorescence in medical and biological samples in vivo, more especially, this invention relates to the use of such an instrument to detect and study breast cancer in vivo, during surgery or in a pathology laboratory. Said device can contain:
.cndot. a portable violet laser (wavelength of 400-420 nm, more or less, and 404 ~ 4 nm in the preferred embodiment) .cndot. a beam spreading device which by expanding and/or scanning, illuminates the specimen to be studied with said laser beam spread out to cover the specimen .cndot. a visualization device which filters out the laser light while passing other visible light produced by fluorescence and permits real time imaging of the sample in said fluorescent light by the human eye .cndot. a focusing imaging device which forms an image not in the human eye .cndot. a recording device which permits recording of said image above (not in the human eye) .cndot. a computer which can be used for analysis and enhancement of said images formed in the recording device, and .cndot. ancillary equipment which permits further study of the light emitted by the specimen, for example, by spectroscopy and the like.

2. According to claim 1, a method and process for illuminating a sample with laser light of violet colour 404 ~ 4 nm, comprising a laser and a beam expanding and scanning device with necessary optics, as known to one skilled in the art.

3. According to claims 1 and 2, a method and a process for filtering the violet light while allowing all other visible light (420 to 750 nm, more or less) to be seen or recorded.

4. According to claims 1 and 2, a method and process for attaching a filter and required optics so that the scientist, oncologist, pathologist, or the like, can make direct visible observations by eye, where appropriate.

5. According to claim 1 and 2, a method and process for magnifying the image of the sample (the sample being in the size range of 0.005m to 1 m, more or less).

6. According to claim 1 and 2, a method and process for recording the image in various states of illumination comprising: white light, laser light, and luminescence.

7. According to claim 1 and 2, a method and process for sampling all or part of an image of interest to obtain the light for further analysis as in a spectroscope or the like.

8. According to claim 1 and 2, a method and process for attaching various types of filters and optical devices to the macroscope, as would be known to one practised in the art, in order to enhance the visibility of areas of interest.

9. According to claim 1 and 2, a method and process for making the entire device portable using:
light emitting diodes, laser diodes, batteries and the like, in a power supply or supplies as known to those skilled in the art.

10. According to claim 1 and 2, a method and process for making the device and all attachments sterile for use in the appropriate hospital or like environment, in one embodiment, this represents a disposable sterile covering.

11. According to claim 1 and 2, a method and a process for illuminating the area of interest using an expanded laser beam and a scrambling device to prevent laser speckle.

12. According to claim 1 and 2, a method and a process for illuminating the area of interest by scanning with a laser beam in a raster pattern.

13. According to claim 1 and 2, a method and a process for changing the size of the laser-illuminated area within the area of interest.

14. According to claim 3, a method and a process for utilising such other filters as required to further enhance observed variability within the sample image.

15. According to claims 1, and 6, a method and a process for recording images for transport or transmission by image media including: ccd, film, and video media.

16. According to claims 1, and 2, a method and a process for replacing the laser with a non-laser light source which can be violet Light Emitting Diodes and filters to restrict the wavelength to 400 to 408 nm, more or less, with a peak half-width of 4 nm, more or less.