Design And Development On Control System Of Accelerator Treatment Head

Radiotherapy is playing a more and more important part in the world as a main treatment of cancer. To increase the radiotherapy gain of the cancer is the main task and goal in the development of radiotherapy technology. At present, the intensity modulated radiation therapy is the most advanced and effective way to increase the radiotherapy gain of the cancer. As necessary equipments of the intensity modulated radiation therapy technology, the medical accelerator treatment head, is fairly important. The control system of medical accelerator treatment head can provide regular and discretionary radiation field, and can adjust the dose intensity dynamically and statically according to X-ray during the radiation therapy. Thus, the radiation dose can be focused to the irregular focal area extremely. So the normal tissues and organs can receive few or avoid unnecessary exposure, and the radiotherapy gain of the cancer and efficiency can be improved.The paper developed the control system of treatment head applied Sliding Window dynamic intensity adjustment control strategy and digital PID control algorithm, through the construction of hardware and software platform of the control module of treatment head collimator and multi-leaf collimator. The control system included collimator control module, multi-leaf collimator control module, accelerator communication network, treatment head software and so on. The collimator control module can provide regular radiation field with different scope, location and angle for radiation therapy, through the control of the motion of jaws and the rotation of treatment head. Multi-leaf collimator control module can provide shape-imitated radiation field and adjust the radiation intensity dynamically according to cancer through the synchronous dynamic motion control of leaves. The full-duplex communication channel of accelerator communication network was constructed by RS-485bus. And the communication between central console and each treatment head control modules was achieved by the definition of application layer communication agreement. The treatment head software, developed on the Visual C++6.0platform, can set various control parameters and achieve the real time supervisory control of the system through the friendly design interface.In this paper, we simulated and tested each function unit, and debugged the entire system in the developing process of each control module, which verified that the function and performances, such as accuracy, reliability and so on, can meet the demand of IMRT.The control system in the paper is the sub-project of Image Guided (IGRT) Accelerator Equipment R&D and Industrialization, a major breakthroughs project in key areas of Guangdong&Hong Kong, which can contribute to the improvement of the technology of medical accelerator positively.