| Radiotherapy is one of the three main techniques of tumor treatment.It can control and kill cancer by ionizing radiation.With the fast development of treatment equipment,techniques and methods,radiotherapy has entered into a new era,in which treatment principle is precise location,precise planning and precise irradiation.The final purpose of precise radiotherapy is to kill cancer and protect the structure and function of normal tissues,which can improve the long-term survival rate and curative effect,making the quality of life better.Setup is an important process in the accurate radiotherapy.The purpose of setup is to fix the position of patients and determine the scope of the tumor location and target area,with the help of position fixing device and auxiliary equipment.Ensure patients treated in the same position.Increase the ray irradiation to the tumor target,and reduce the ray irradiation to the normal organs.So patients who are setup accurately directly affect the efficacy of treatment.Three-dimensional laser positioning system is an important part of CT simulation,which is used for determining treatment iso-center of tumor for patient by projecting out three markers on the body surface.It ensures the position which the patient treatment every time is consistent with CT simulation positioning and makes the radiation treatment process more precise.Three-dimensional laser positioning system is usually installed in CT simulation room.It assists setup by moving laser or cooperating with moving couch of CT.Through the investigation,we learned that there are three types of laser positioning system which are used in national hospital,including DRADO1,DORADO3 and DORADO4.Each types of laser positioning system involve different coordinate system conversion,unit conversion and the calculation of location data.It brings trouble to determining the iso-center of patient and prone to error,which is bad for patient's accurate treatment.This paper combined clinical application and the knowledge of computer software as well as mathematical knowledge to design programming which can used to different types of laser positioning system and convenient for the operator's work.It simplifies the work steps,reduces the working time and improves work efficiency.In order to further verify the accuracy and precision of the program,Excel is been used to randomly selected the group of 21 data.Use the phantom of Catphan to simulate the treatment process of patients,including target positioning,target delineations,planning and reset.Cone-beam CT is used to scan phantom which has finished the setup.The scanning images match in the planning system images,getting the positioning error values of X(left or right)axis,Y(ventral or dorsal)axis and Z(head or foot)axis.Verify the accuracy and precision of laser positioning system and the program been used.Esophageal cancer,cervical cancer and lung cancer are three higher incidence tumor diseases.Radiotherapy is used to treat them.This paper studies the laws of three tumors translocation when the iso-center of simulation move to the treatment iso-center.The result not only provides more accurate operation for the technical personal,but also provides reference for the physics designing plan.Then,the results are applied to the phantom of Catphan.The program is used to calculate the coordinate of treatment iso-center and Cone-beam CT is used to verify the accuracy of the setup error.It perfects the treatment process of esophageal cancer,cervical cancer and lung cancer.Provide more accurate service for patient.In short,the program has many advantages,such as simple structure,high portability,accuracy calculation,controlling and so on.The program also can meet the clinical need.It is able to calculate the transformation of coordinate system effectively and ensure the accuracy of setup,which is of great significance for lowering dose of normal tissues,ensuring the accuracy of whole radiotherapy process,and improves the quality of life. |
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