基于ARM的LED光热治疗系统设计与初步实验研究
发布时间：2018-11-25 22:25
【摘要】：光热治疗是一种以光和热为主要物理因子的理疗方法，通过特定波长的光照射人体组织产生的光化学效应和热效应来治疗皮肤疾病、妇科疾病以及浅表部位的癌症等疾病。光热治疗具有无创、副作用小的优点，而且可以和其他治疗方法相结合，在临床上得到了广泛的应用。光热治疗中的热效应会引起组织温升，温度可以反映了组织对光的吸收情况。对于某些疾病而言，只有在一定温度阈值范围之内，，光热治疗才能达到预期的治疗作用。因此温度直接反应了光热治疗的效果，是临床治疗中需要控制的参数。控制组织的温升可以引导光热治疗，使其更加安全有效，但是一般的光热治疗仪器都缺少对组织温度控制的功能。 为了实时监测光热治疗过程中照射部位组织的温度，本文基于ARM920T架构的S3C2440和Linux嵌入式操作系统设计了温度可控的LED光热治疗系统。大功率LED的性能随着半导体技术的发展得到了很大进步，是光热治疗辐射光源的理想选择。系统硬件由LED阵列光源驱动部分、温度采集部分、微处理器部分以及人机交互部分组成。针对大功率LED阵列的特性和发光要求，以LM3406芯片为核心的恒流驱动电路驱动电流达到了1.2A并且具有PWM调光功能；红外测温模块TN901采用热电堆传感器采集目标温度，通过SPI接口将温度信号传输给微处理器S3C2440；S3C2440外围电路包括的串口、USB接口、JTAG接口以及液晶触摸屏模块实现系统的通信、调试、数据传输和人机交互。系统软件设计分为驱动程序和应用软件GUI两部分，驱动程序根据硬件设备的需要编写，应用软件在QtCreator集成开发环境下设计。用户界面分为光热治疗参数设置界面、PID控制界面和温度曲线绘制界面。本文根据光热治疗中人体组织对温度控制的要求，对传统的PID算法进行了改进，加入了积分分离环节。由目标温度和TN901采集的组织温度通过积分分离PID算法计算PWM信号的占空比，进而调节LED输出的光功率密度，实现了组织温度的精确控制。 完成LED光热治疗系统设计后，通过万用表和激光能量计测量了不同PWM占空比下的LED工作电流和输出光功率密度，测试结果表明PWM信号可以线性调节这两个参数。选用新鲜的猪皮作为离体组织样品进行光热治疗的模拟实验，对系统温度控制性能进行测试，实验结果显示系统的温度控制效果好、品质高，最大过冲量不超过1℃，稳态误差为±0.5℃，能够满足光热治疗对温度控制的要求。本文还对红光缓解肌肉疲劳进行了初步的实验研究，分析了志愿者实验中采集的指力信号，并对实验提出相关的改进方法，为以后进一步深入研究奠定了基础。
[Abstract]:Photothermal therapy is a physiotherapy method with light and heat as the main physical factors. The photochemical and thermal effects of light irradiation on human tissues are used to treat skin diseases, gynecological diseases and superficial cancer. Photothermal therapy has the advantages of noninvasive, less side effects, and can be combined with other treatment methods, and has been widely used in clinical. The thermal effect of photothermal therapy can cause tissue temperature to rise, which can reflect the absorption of light. For some diseases, only within a certain temperature threshold range, photothermal therapy can achieve the desired therapeutic effect. Therefore, temperature directly reflects the effect of photothermal therapy and is a parameter to be controlled in clinical treatment. Controlling tissue temperature rise can lead to photothermal therapy and make it safer and more effective, but the common photothermal therapy instruments lack the function of tissue temperature control. In order to monitor the temperature of irradiated tissue in the course of photothermal therapy in real time, a LED photothermal therapy system with controllable temperature was designed based on S3C2440 and Linux embedded operating system based on ARM920T architecture. With the development of semiconductor technology, the performance of high power LED has been greatly improved, and it is the ideal choice of radiation source for photothermal therapy. The hardware of the system is composed of LED array light source driving part, temperature acquisition part, microprocessor part and man-machine interaction part. According to the characteristics and luminescence requirements of high power LED array, the driving current of the constant current drive circuit with LM3406 chip as the core is 1.2A and has the function of PWM dimming. The infrared temperature measurement module TN901 uses thermoelectric reactor sensor to collect the target temperature and transmits the temperature signal to microprocessor S3C2440 through SPI interface. The peripheral circuit of S3C2440 includes serial port, USB interface, JTAG interface and LCD touch screen module to realize system communication, debugging, data transmission and man-machine interaction. The software design of the system is divided into two parts: driver and application software GUI. The driver is written according to the need of hardware equipment. The application software is designed under the environment of QtCreator integrated development. The user interface is divided into photothermal therapy parameter setting interface, PID control interface and temperature curve drawing interface. According to the requirement of temperature control in human tissue during photothermal therapy, the traditional PID algorithm is improved and integral separation is added. The duty cycle of PWM signal is calculated by the integral separation PID algorithm from the target temperature and the tissue temperature collected by TN901, and then the optical power density of LED output is adjusted to realize the accurate control of the tissue temperature. After the design of LED photothermal therapy system, the working current and output optical power density of LED under different PWM duty cycle are measured by multimeter and laser energy meter. The results show that PWM signal can adjust these two parameters linearly. Using fresh pig skin as the sample of photothermal treatment in vitro, the temperature control performance of the system was tested. The results showed that the temperature control effect of the system was good, the quality of the system was high, and the maximum impulse was less than 1 鈩
本文编号：2357544
[Abstract]:Photothermal therapy is a physiotherapy method with light and heat as the main physical factors. The photochemical and thermal effects of light irradiation on human tissues are used to treat skin diseases, gynecological diseases and superficial cancer. Photothermal therapy has the advantages of noninvasive, less side effects, and can be combined with other treatment methods, and has been widely used in clinical. The thermal effect of photothermal therapy can cause tissue temperature to rise, which can reflect the absorption of light. For some diseases, only within a certain temperature threshold range, photothermal therapy can achieve the desired therapeutic effect. Therefore, temperature directly reflects the effect of photothermal therapy and is a parameter to be controlled in clinical treatment. Controlling tissue temperature rise can lead to photothermal therapy and make it safer and more effective, but the common photothermal therapy instruments lack the function of tissue temperature control. In order to monitor the temperature of irradiated tissue in the course of photothermal therapy in real time, a LED photothermal therapy system with controllable temperature was designed based on S3C2440 and Linux embedded operating system based on ARM920T architecture. With the development of semiconductor technology, the performance of high power LED has been greatly improved, and it is the ideal choice of radiation source for photothermal therapy. The hardware of the system is composed of LED array light source driving part, temperature acquisition part, microprocessor part and man-machine interaction part. According to the characteristics and luminescence requirements of high power LED array, the driving current of the constant current drive circuit with LM3406 chip as the core is 1.2A and has the function of PWM dimming. The infrared temperature measurement module TN901 uses thermoelectric reactor sensor to collect the target temperature and transmits the temperature signal to microprocessor S3C2440 through SPI interface. The peripheral circuit of S3C2440 includes serial port, USB interface, JTAG interface and LCD touch screen module to realize system communication, debugging, data transmission and man-machine interaction. The software design of the system is divided into two parts: driver and application software GUI. The driver is written according to the need of hardware equipment. The application software is designed under the environment of QtCreator integrated development. The user interface is divided into photothermal therapy parameter setting interface, PID control interface and temperature curve drawing interface. According to the requirement of temperature control in human tissue during photothermal therapy, the traditional PID algorithm is improved and integral separation is added. The duty cycle of PWM signal is calculated by the integral separation PID algorithm from the target temperature and the tissue temperature collected by TN901, and then the optical power density of LED output is adjusted to realize the accurate control of the tissue temperature. After the design of LED photothermal therapy system, the working current and output optical power density of LED under different PWM duty cycle are measured by multimeter and laser energy meter. The results show that PWM signal can adjust these two parameters linearly. Using fresh pig skin as the sample of photothermal treatment in vitro, the temperature control performance of the system was tested. The results showed that the temperature control effect of the system was good, the quality of the system was high, and the maximum impulse was less than 1 鈩
本文编号：2357544
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