立体定向放射治疗照射野剂量分布特点及应用

Charateristic of dose distribution and its clinical application in stereotactic radiotherapy practice

目的:测量目前广泛应用的立体定向放射治疗系统(SRT—X刀)准直器射野的临床剂量学参数,探索正确的临床使用方法。材料与方法:用组织等效固体水模、仿真人体头模和胶片剂量测量系统测量BrainLAB X刀系统在静态、单靶(中心)旋转、两靶旋转照射时的离轴比、半影、锐度、平坦度等剂量学参数。结论:了解和掌握不同照射技术时,X刀准直器射野剂量学参数的变化是正确使用立体定向放射治疗技术的一个关键因素,特别是在鼻咽癌的多靶点补量治疗时尤为重要。本文提出了临床使用时的一些具体建议。

Purpose: To measure clinical dosimetric parameters and to evaluate the accuracy of isocenter dose distribution in circular collimater fields in stereotactic radiotherapy for correctly using of stereotactic radiotherapy in clinical practice. Materials and Methods: Polystyrene phantom, Anthropomorphic head phantom and film-checking technique were used to measure the parameters of off-axis ratio, penumbra, steepness and flatness of isodose curves under static, single-target, and 2-targets-isocenters moving fields condition in BrainLAB X-knife system. Conclusion: Our parameters obtained from above-mentioned different measurement methods demonstrated that to understand thoroughly the variations of clinical dosimetric parameters at the isocenter of circular collimeter fields is one of the key factors for performing correctly the stereotactic radiotherapy techniques in clinical practice, such as, when you choose multi-targets X-knife therapy method for the nasopharyngael carcinoma. Some suggestions were offered according to the results of our test measurements for guiding the correct application of stereotactic radiotherapy in clinical practice.