放疗中呼吸引起的组织深度波动对吸收剂量的影响

目的研究放疗中呼吸引起的组织深度波动对吸收剂量的影响。方法在不同能量、组织深度波动幅度、呼吸频率及平均测量深度时，分别用研制的能模拟组织深度波动的辐射剂量测量水箱进行测量，以获得“组织深度波动因子”（Fdw）进行比较。结果组织深度波动确实对实际吸收剂量有影响，而且组织深度波动幅度、呼吸频率及射线能量越大，Fdw值越小，即对吸收剂量的影响越大，而Fdw与平均测量深度无关。结论放疗中必须根据患者的呼吸频率、所用射线类型及呼吸引起的组织深度波动幅度用Fdw对肿瘤或组织的实际吸收剂量进行修正，以提高疗效。

Effect of organ depth ware on absorbed dose by respiration of patient in radiotherapy

Objective To study how the absorbed dose was affected by the wave of organ depth caused by respiration of patient in radiotherapy. Methods With the change of radiation energy, organ depth waving range, respiration frequency and measuring depth, the organ depth waving factor (F- dw ) was determined with the waterphantom which could simulate the actual organ wave of patient in radiotherapy. Results The actual absorbed dose was really affected by the organ depth wave of patient in radiotherapy. The F- dw value decreased with the increase of radiation energy, depth waving range and respiration frequency, which means that the higher these three parameters, the more the absorbed dose was affected. But the average depth measured had no effect on the F- dw value. Conclusions The absorbed dose to organ or tumor should be modified with the measured F- dw based on the patient's respiration frequency, radiation energy and actual organ depth waving range, so as to improve the effect of radiotherapy.