Research On PDT Laser Wavelength Secondary Temperature Regulation Technology

Photodynamic therapy(PDT)is a new technique for minimally invasive treatment of cancer and a new field of rapidly developing medical research.Light provides the stimulation energy in PDT,Semiconductor laser has small volume,high efficiency,long service life,convenient operation etc.Coupled with optical fiber,semiconductor laser can be used for endoscopic device,the deep tissues or organs of cancer therapy,Therefore,the use of photodynamic therapy is increasingly widespread.At present,the best laser wavelength matching PHOTOFRIN ? photosensitizer is 630nm.However,due to the limitation of domestic semiconductor technology,there is no dedicated 630nm laser chip at home,but only semiconductor lasers with a wavelength range of 635nm-638nm produced.But because of 5-8 nm wavelength deviation,photosensitizer drug is hard to produce good chemical excitation effect.So that it is unable to get the peak efficacy of drugs.Moreover,the 635nm-638nm wavelength semiconductor laser is hard to pass the authentication of the medical system.As a result,this situation has become a major obstacle to the promotion of PDT technology.Aiming at the current situation of semiconductor light source in PDT at home and abroad,we proposed a two level temperature control model.The precision control technology of the central wavelength of semiconductor laser is realized.The wavelength of the domestic laser is shifted from 635nm to 630nm,which is in line with the demand of the product.In this paper,the temperature model of typical 635nm red laser source system was first established.Using the SOLIDWORKS tool software,we not only completed the simulation analysis of the structure design,stress distribution,heat conduction dynamic distribution of the key components and the simulation analysis of steady temperature gradient,but also calculated the influence of structural parameters on the system performance.In the end,the temperature difference parameters inside and outside the light source,heat sink temperature distribution model were obtained by the simulation analysis of the temperature,providing basis for evaluating the heat dissipation capacity of heat pipe radiator under different environments and different working conditions,and set up the two level temperature control model?Through the heat conduction simulation analysis of the two stage temperature control model,it is concluded that the conduction state of the model is good.After a large number of practical tests,the temperature of the model is measured and the temperature of the core of the laser tube is stabilized at 7.00±0.3? and the laser wavelength is offset to the experimental results of 630.00 ± lnm.The conclusion is drawn that the two stage temperature control model can accurately control the temperature and wavelength of the laser.At the same time,the temperature drift of the precision current source is solved.And by the optimization of the internal heat distribution,conduction,convection,radiation and other design technology,we met the wavelength shift of PDT device level and long-term stability system demands,and meanwhile assisted multiple PDT medical equipment dealers to complete the FDA certification.