Proceedings - Viện Vật lý

_________________________________________________________________________________Những tiến bộ trong Quang học, Quang tử, Quang phổ và Ứng dụng. 8/2006, Cần Thơ, Việt Namequienergy density corresponding to the wavelength 940nm spreads in anarea of 12mm in the radial direction, with the depth 12,5mm. It means that inthe white matter laser beam 940nm is scattered more than laser beam 633nm,so the energy distribution of 940nm is larger than that of 633nm. With the63equienergy density 1x10 J / mm , the depths corresponding to wavelengths633nm, 850nm, and 940nm are 25mm, 22.5mm and 18.5mm. As in [3],simulating the photon propagation in skin showed that the penetration depthof 940nm photon is largest, while in the brain, wavelength 940nm affectsmore in the radial direction, and laser beam of 850nm and 633nm can gofurther in the brain.3.2. ATP concentration synthetized in brainATP (Adenosine Triphosphate), molecule synthesized at mitochondria,has two important roles in living organism . They are supplying energy forall maintenance and synthetic activities of the body, and forming cAMP,important molecule in the activities of many hormones. The concentration of15 3ATP in the tissue is about 10 mm . The binding energy of a high energyphosphate bond of an ATP is about 0.32 (eV). From the distribution ofphoton energy, the rate of ATP concentration synthetized in brain whenirradiated by 633nm, 850nm and 940nm laser beams is calculated and shownin Figure (2), (4) and (6).In a region of 4mm in the radial direction and the depth of 12,5mm, laser12 31beam 633nm can create 1x10 (mm .s ) ATP, while laser beam 940nm cancreate with the same rate in a region of 16 mm in the radial direction and thedepth of 15mm. But to go further in the brain, with the rate10 3 1of 1x10 (mm .s ), the depth corresponding to the wavelength of 633nm,850nm, 940nm are 25mm, 27.5mm and 21mm respectively. It means thatlaser beam 850 nm can help to synthetized ATP at the largest depth. So acombination of two wavelengths 940nm and 850nm will affects in a largeand deep region of the brain.Fig. 1: Energy distribution of laserbeam 633nm in white matterFig. 2: Rate of ATP concentrationsynthesized in white matter whenirradiated with laser beam of 633nm280