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ISSN 1062 8738, Bulletin of the Russian Academy of Sciences: Physics, 2009, Vol. 73, No. 10, pp. 1341­1344. © Allerton Press, Inc., 2009. Original Russian Text © V.N. Kurlov, I.A. Shikunova, A.V. Ryabova, V.B. Loschenov, 2009, published in Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya, 2009, Vol. 73, No. 10, pp. 1420­1423.

Sapphire Smart Scalpel
V. N. Kurlova, I. A. Shikunovaa, A. V. Ryabovab, and V. B. Loschenov
a

b

Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia b Center of Natural Research, General Physics Institute, Russian Academy of Sciences, Moscow Russia e mail: kurlov@issp.ac.ru

Abstract--A new type of surgical instruments--sapphire scalpel with an opportunity of simultaneous resec tion and fluorescent diagnostics of a resected tissue state close to the cutting edge, allowing the surgeon to differ between the cancerous and normal tissues during operation--has been developed. DOI: 10.3103/S1062873809100086

Success of operation is conditioned on the one hand by surgeon's skills and, on the other hand, by the instrumentation capabilities. Currently the studies aimed at searching for new materials for scalpel and optimizing its cutting edge and on expansion of scal pel functional capabilities that can provide addi tional information on the state of dissected tissue are under way. One of the most promising materials for fiber surgi cal scalpels is sapphire because of its unique combina tion of optical and mechanical properties. Sapphire has a wide optical transmission band, high melting temperature, good thermal conductivity, strength, chemical inertness, and bio compatibility [1]. Sap phire scalpels substantially exceed those made of spe cial medical steels. High sapphire hardness provides a scalpel cutting edge with a rounding radius of 25 nm (for comparison: the rounding radius of metal scalpel edge is 500 nm), which substantially decreases the tis sue damage at resection and reduces the post opera tion rehabilitation period [2]. Sapphire edges have a higher stable cutting edge, longer service life, and low friction coefficient; they can also sustain repeated sterilization of any type without risk of changing edge geometry. Sapphire scalpels have also a number of advantages in comparison with nonmetal instruments. They are much less expensive than diamond scalpels [3] and are not limited in size to be used only in micro surgery. As compared to ceramic ones [4, 5], sapphire scalpels have a cutting edge rounding of smaller radius and optically transparent edge. The edge transparency makes it possible to supply laser radiation directly to the resection zone not only to enlighten it and improve visualization of blood vessels and other structures [6] but also to affect in various ways the tissues during operation [7]. The work on expansion of scalpel functional capa bilities is carried out in two ways: to ensure capability of detecting possible deviations of biotissue "mechan ical" parameters by miniature (temperature, pressure, etc.) sensors built in the edge [8­10] and to develop

optical diagnostics systems. In particular, to determine the degree of tissue malignancy, a system using a semi conductor laser has been developed; blood microsam ples taken from the dissection area are introduced into the space between its mirrors [11]. The principle of its operation is based on the analysis of the eigenfre quency shift for a cavity with a test and change in the amplitude of radiation from the cavity; such an analy sis allows one to estimate the protein content in the test, which differs in healthy and cancerous cells. One of the main disadvantages of this diagnostic system is the extremely low operation speed: it processes an area of 1 cm2 for 1 h. We propose here a radically new type of surgical instruments: scalpels with an opportunity of simulta neous resection, laser photodynamic impact on the biotissues adjacent to the edge, and fluorescent diag nostics of the dissected tissue state near the cutting edge directly during surgical operation on resection of malignant tumor. The principle of fluorescent diag nostics is based on the capacity of dyes (photosensitiz ers selectively accumulated in malignant tissue) intro duced into the body to effectively absorb laser radia tion in a certain spectral range and emit some part of absorbed energy (fluoresce) [12]. Measuring the parameters of this radiation, one can carry out spectral fluorescent diagnostics and draw conclusions about the presence of cancerous cells in the tissue. The principle of the new diagnostic system is based on the use of sapphire edge with isolated channels, whose end faces are in the immediate vicinity of the scalpel cutting edge (Fig. 1). The channels contain optical quartz fibers, one of which is for supplying flu orescence exciting radiation or coagulation radiation to the tissue dissection region, while the other fiber (or fibers if there are more than two channels) are for transmitting fluorescence radiation from the dissec tion region to the spectrometer for fluorescent diag nostics in this region.

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KURLOV et al. (a) 6 5 4 3 (a) 2 1 0 mm (b)

(b)
Fig. 1. (a) Appearance of the edge of the laser spectro scopic scalpel made of sapphire ribbon with capillary channels with an internal diameter of 0.5 mm and (b) the formation of maximum laser radiation density in the resec tion zone.



To obtain a diagnostic scalpel of minimum thick ness, sapphire ribbons with capillary channels 500 µm in diameter (this value permits location of standard quartz fibers 400 µm in diameter in the channels) were grown. The formation and maintenance of channels of such diameter (close in size to the melt meniscus height) in the sapphire ribbon requires, first of all, to prevent channels from collapsing during growth due to the increase in the Laplace pressure in the meniscus with a decrease in the average curvature radius of the meniscus surface (decrease in the channel diameter) and with an increase in the meniscus height, which excludes supercooling at the crystallization front and, consequently, yields a high quality ribbon. The problem was solved by not only optimizing the growth rates and temperature modes in the crystalliza tion zone but also using new approaches to the shaper design and the system controlling the crystallization front state. Various shaper versions have been devel oped to provide optimal temperature distribution in the crystallization zone area due to the difference in the relative heights of shaper working end face in the zone of capillary channel and ribbon perimeter. Extra opportunities (change in the pressure above the shaper channel forming hole) were also used to form and maintain the channel size, which made it possible to control the channel collapse and repeated formation in the ribbon bulk. Sapphire ribbons with capillary channels 500 µm in diameter (spaced by a distance of 500 µm) were grown by the EFG (edge defined film fed growth) Stepanov method in an induction heating facility with weight

Fig. 2. (a) Calculated light distribution on the inclined edge face near the cutting edge and (b) modeled ray paths in a tissue with optical characteristics of liver (edge height 5 mm, distance between capillary channels 2 mm).

sensor control. Figure 1a shows the edge obtained by mechanical treatment of this ribbon. A conical light beam with a divergence angle of 10°­30° emerges from the optical fiber located in the sapphire edge channel and is incident on the channel end surface, completely (except for the Fresnel loss) passing through the interface. When passing through sapphire, all rays are incident on the oblique edge planes. Then the edge operates as an optical wedge. In other words, after several complete internal reflections at the sapphire­biotissue interface, the angle of inci dence of each ray becomes less than the critical angle for these two materials (sapphire and biotissue) and each subswquent rereflection increases the energy emerging from the crystal edge. Thus, two zones of high radiation density are formed at both oblique edge faces near the cutting edge, which is proved by model ing the optical ray pass (Fig. 2a). All rays supplied by optical fiber directly to the cutting edge region are involved in the formation of these zones. The distal ends of optical fibers are located near the cutting edge; this arrangement makes it possible to capture the fluorescence from adjacent tissues by the detecting fiber in amounts sufficient for spectral diag nostics with photosensitizers. The radiation density used for fluorescent diagnos tics varies from several units to 30 mW/cm2. For most soft tissues this energy is dissipated mainly within a tis sue volume of 2 mm3 of biological. Therefore, infor
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SAPPHIRE SMART SCALPEL rel. units 1.0 1.0 0.5 mg/kg 0.1 mg/kg 0.05 mg/kg 0.01 mg/kg 0.005 mg/kg 0.001 mg/kg 0 mg/kg

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1 0.5 2 3 4 600 640 680 720 760 800 nm

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Fig. 3. Fluorescence spectra obtained with a sapphire scal pel for different photosensitizer concentrations in gel.

Fig. 4. Fluorescence spectra obtained at mouse tumor resection by the new sapphire scalpel with spectral diag nostics control by the Photosense photosensitizer with the edge position (1) outside and (2) inside the tumor (the tumor is under the skin), (3) in the healthy muscle, and (4) the control measurement for human arm (tissue norm).

mation on the photosensitizer concentration in tissue can be obtained for this volume. Modeling and statistic calculation (by the Monte Carlo method) of the optical system showed that, due to the high degree of radiation dissipation by tissues, the light field form in the tissue is independent of the angle between the fiber axis and the edge (edge incli nation angle); it is close to spherical and is formed on the fiber axis continuation in the tissue = 90°), shift ing with a decrease in the edge inclination angle by several tenths of a millimeter upward from the edge: up to 0.6 mm at = 30° (Fig. 2b). An increase of the dis tance between the fibers leads to a decrease in the number of signal photons entering the diagnostic fiber, which negatively affects the sensitivity of the system. The edge channel for the irradiating fiber should be located so as to form the light field from the irradiating fiber primarily in the vicinity of the inserted part of the edge. The channels for the irradiating and diagnostic fibers must be parallel and located spaced by a mini mum distance. We experimentally tested the sapphire smart scalpel based on the sapphire edge with an inclination angle of 30° and a small distance between the channel axes: 0.8 mm (Fig. 1). The smart scalpel sensitivity to the concentration of trisulfophthalocyanine hydroxyalu minum photosensitizer ("Photosens") in the model medium was evaluated. To this end, a weakly scatter ing gel with a photosensitizer concentration compati ble with therapeutical (5 mg/kg of aluminum phthalo cyanine) or lower was prepared. The data obtained were processed using laser fiber spectroanalyzer (LECA 01 Biospek). The data obtained with the sapphire smart scalpel on gel samples were compared with the data of video fluorescent diagnostic system (Biospek) for the same samples. The sensitivity of the system based on the sapphire scalpel allows one to measure Photosense

concentrations of about 0.001 mg/kg, which is smaller by a factor of 5000 than the average therapeutical doze (Fig. 3). Such a sensitivity cannot be obtained with a video fluorescent diagnostic system (Biospek). The scalpels developed were tested in experiments on mice with interwoven intramuscular tumor (Erlich carcinoma). A day prior to the operation Photosense photosensitizer was injected to each mouse in a dose of 5 mg/kg. A cw 50 mW semiconductor laser with a wavelength of 633 nm was used. The fluorescence spectra obtained during scalpel resection show that the maximum fluorescence intensity captured by the edge in the malignant tumor exceeds the maximum fluores cence intensity for a healthy tissue by a factor of more than 3 (Fig. 4). Such measurements, processing, and analysis of real time data (continuous monitoring) allow a surgeon to distinguish between cancerous and healthy tissues directly during surgical operation on malignant tumor resection. CONCLUSIONS Based on the technique for growing sapphire rib bons with capillary channels, a radically new type of surgical instruments has been developed: scalpels for simultaneous resection and fluorescent diagnostics of dissected tissue state near the cutting edge, which allows a surgeon to differ between cancerous and nor mal tissues directly during operation. The system based on the sapphire edge with integrated optical fibers, irradiating and diagnostic ones, has demon strated a high spectrometric sensitivity in experiments with models (gels); this parameter is well compared with the fluorescent diagnostics systems for malignant diseases. The cutting edge with a small rounding radius, whose faces form an optical wedge, serves also to efficiently accumulate light energy from the emit ting fiber in the edge channel in the local area of pri
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KURLOV et al. 4. Shellock, F.G. and Shellock, V.J., J. Magn. Resonance Imaging, 2005, vol. 6, p. 954. 5. Shevchenko, A.V., Dudnik, E.V., Ruban, A.K., et al., Nauka Proizvodstvu, 2007, no. 6, p. 36. 6. Dobrovinskaya, R.E., Litvinov, L.A., and Pishchik, V.V., Entsiklopediya sapfira (Encyclopedia of Sapphire), Khar'kov: Institut Monokristallov, 2004. 7. Doty, J.L. and Auth, D.C., IEEE Trans. Biomed. Eng., 1981, vol. BME 28, no. 1, p. 1. 8. Rebello, K.J., Lebouitz, K.S., and Migliuolo, M., MEMS Tactile Sensors for Surgical Instruments. Mat. Res. Soc. Proc., 2003, vol. 773, p. 55. 9. Lebouitz, K. and Migliuolo, M., US Patent 0116022, 2002. 10. Carr, W.N. and Ladocsi, L.T., US Patent 5980518, 1999. 11. Gourley, P.L., J. Phys. D, 2003, vol. 36, p. R228. 12. Loschenov, V.B., Konov, V.I., and Prokhorov, A.M., Laser Phys., 2000, vol. 10, p. 1188.

mary (initial) tissue dissection for photodynamic impact or coagulation. ACKNOWLEDGMENTS This study was sup[ported in part by the Russian Foundation for Basic Research, project no. 08 02 00756 a, and the Program "Support for Innovations, 2008" of the Russian Academy of Sciences. REFERENCES
1. Klassen Neklyudova, M.V., Bagdasarov, Kh.S., et al., Rubin i sapfir (Ruby and Sapphire), Moscow: Nauka, 1974. 2. Zharov, V.P. and Latyshev, A.S., J. Laser Appl., 1999, vol. 11, p. 80. 3. Keel, D.M., Goldman, M.P., Fitzpatrick, R.E., and Butterwick, K.J., Lasers Surg. Med., 2002, vol. 31, p. 41.

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2009