Dosimetric Research On Rotating Gmama Systems For Stereotactic Body Radiotherapy

With the development of the teconolgoy in radiotherapy, we are step in the age ofprecise radiotherapy. The IMRT and ART teconology help us to reach the uniform dosedistribution and reduce the organ of risk accepted dose. It will get higher benefit intumor radiotherapy. But when the volume of tumor is so small, tumor inside organ ofrisk, and the limitted dose of organ of risk is almost very low. Even if the IMRTteconology will not reach the dose grads in50%at the edge of tumor.In1951, professor Lars Leksell advanced the idea of Stereotactic raidiosurgy.Also in90th, OUR company created the first rotated body gamaknife in China. Thetherapy mode of the body gama kinfe is using the taper rotated collimator and focusingthe gama ray to one point. The dose distribution will reach the Bragg peak like protontherapy. Also the higher dose, the closer in the center region. However, the SBRTteconology is different between Linac accelerator. Now it is not enough that we only dothe QA&QC for body gama knife in one target point physical dose distribution in theworld. Therefore, the higher quality in quality assurance and quality control for bodygama knife should be done in mechanism, phisics and dose distribution.This paper first reviews the history of stereotatic radiotherapy, development and thebrief facility. Also introduces the theory and the structure of Body gama kniferadiotherapy system. Second, we mainly research the mechanism accuracy, focusposition accuracy and the delivered dose distribution verification. Third, we will test thetreatment plan for contrasting the dose distribution between in plan and in delivered.The conclusion will affect how big the PTV(plan target volume). And the PTV willaffect the toxicity of OAR(organ at risk) arround the PTV. Also the dose distributionaccuracy will affect the local control rate and whether the gross tumor reached theenough x-ray dose. So it is important that we should ensure the safty of the stereotaticbody gama knife radiotherapy, provide every patient the most accuracy gama kniferadiotherapy and the lower toxicity.