鼻咽癌放疗中的垂体屏蔽技术

THE PITUITARY SHIELDING TECHNIQUE IN THE RADIOTHERAPY OF NASO PHARYNGEAL CARCINOMA

目的：研究在鼻咽癌放射治疗中对两侧耳前野进行垂体屏蔽前后垂体的剂量分布变化，以了解该技术对保护垂体功能的意义。材料与方法：采用治疗计划系统分析计算鼻咽癌放疗中采用两侧耳前野垂体屏蔽技术后垂体的受量分布，与不采用者进行比较，并用胶片法测量结果加以验证。结果：①治疗计划系统计算结果显示采用两侧耳前野垂体屏蔽技术后垂体在鞍底及垂体中平面剂量约为不采用者的一半，且屏蔽后垂体的容积剂量较不屏蔽者减少。②胶片法测定结果显示采用屏蔽技术后垂体在鞍底部位受量约为５０％。结论：初步研究认为本文采用的垂体屏蔽技术降低了垂体受量，相同剂量水平下的垂体受照射体积亦有明显减少，它可以起到保护垂体功能的作用。

Purpose:To quantify the blocking efficiency in the pituitary region during the external beam irradiation of naso pharyngeal carcinoma so as to decrease.its radiation complications. Methods and materials:the doses received by the pituitary in cases of presence and absence of the shielding blocks in two pre auricular fields were evaluated by the method of Dose volume Histogram provided by the TPS,the results were then compared with those from the film dosimetry. Result:DVH results show that the dose of pituitary reduced one fold at the bottom and middle level of pituitary and volumetric dose reduced apparently while the dose at mid plane of the naso pharynx rests the same by using the shielding technique, and this is confirmed by the film dosimeter. Conclusions:shielding of the pituitary in two pre auricular fields can reduce not noly the dose but also the irradiated volume at the same dos level in the pituitary region, and this indicates that such kind of technique might be clinically efficient and practical.