不同膀胱状态对宫颈癌腔内后装放射治疗剂量分布的影响研究

Effect of different bladder conditions on dose distribution of radiotherapy for cervical cancer

目的探讨不同膀胱状态对宫颈癌腔内后装放射治疗剂量分布的影响。方法选取确诊为宫颈鳞状上皮细胞癌患者15例作为研究对象,不同膀胱状态时进行CT扫描,计算B点、Y点、R1点、R2点、RP点、R3点、R4点、BL点的剂量,并计算膀胱充盈状态时bx点的剂量以及不同膀胱状态下膀胱的D0.1cc、D1cc和D2cc值。结果B点、Y点、R1点、R2点、RP点、R3点、R4点剂量分别为A点剂量的(26.48±1.32)%、(1601.88±258.61)%、(68.52±2.75)%、(70.12±1.35)%、(72.74±2.30)%、(55.06±0.93)%、(46.98±0.77)%,不同的膀胱状态B点、Y点、R1、R2、RP、R3、R4剂量占A点剂量百分率比较,差异无统计学意义(P﹥0.05);BL点剂量为A点剂量的(78.68±0.87)%,其中BL点剂量在膀胱排空时为A点剂量的(77.45±0.95)%,在膀胱充盈时为A点剂量的(79.85±0.75)%,两者之间差异具有统计学意义(P﹤0.05)。单通道、三通道施源器行腔内后装放射治疗时膀胱充盈状态BL参考点剂量高于膀胱排空时。单通道、三通道施源器行腔内后装放射治疗,bx点的剂量均显著高于BL点的剂量,差异均有统计学意义(P﹤0.01)。三通道施源器行腔内后装放射治疗的轴状面可以得到bx点在750 c Gy等剂量曲线内,而BL点在500~750 c Gy等剂量曲线,同矢状面。膀胱充盈状态时,膀胱的D0.1cc、D1cc和D2cc虽均低于膀胱排空时,但差异无统计学意义(P﹥0.05)。结论不同的膀胱状态B点、Y点、R1、R2、RP、R3、R4剂量无差别,膀胱充盈状态时BL参考点剂量增大,膀胱底部剂量点bx剂量高于BL参考点,不同膀胱状态对膀胱剂量影响较小。

Objective To investigate the effect of different bladder conditions on the dose distribution of radiotherapy in the treatment of cervical cancer. Method 15 cases of clinically confirmed cervical squamous cell carcinoma were in-cluded in the analysis, and CT scan was performed in patients with different bladder condition, of which the dose of B, Y, R1, R2, RP, R3, R4, BL were calculated, and the dose of bx in the bladder filling state, the D2cc, D1cc and D0.1cc in differ-ent bladder states were analyzed. Result The ratio of dose at B, Y, R1, R2, RP, R3, R4 to dose at A were （26.48±1.32）%, （1601.88±258.61）%, （68.52±2.75）%, （70.12±1.35）%, （72.74±2.30）%, （55.06±0.93）%, （46.98±0.77）%, respectively, and the dose ratio of B, Y, R1, R2, RP, R3, R4 to A in different bladder states were of no significant differences （P〉0.05）. In the intracavitary brachytherapy using single channel or three-channel applicators, the reference dose of BL was significantly higher in bladder filling state than that in bladder emptying state （P〈0.05）, and the dose at bx was higher than that of BL, with significant difference observed （P〈0.01）. In the axial plane of the intracavitary brachytherapy of three-channel appli-cators, it was found that bx was in the isodose curve of 750 cGy, while BL was in the isodose curve of 500 cgy^750 cGy, same with that in sagittal plane. As in bladder filling state, the D0.1cc, D1cc and D2cc were lower than those in bladder emptying state, though the difference was not significant （P〉0.05）. Conclusion The dose of B, Y, R1, R2, RP, R3, R4 are similar in different bladder states, and the dose of BL reference point is increased in the bladder filling state, while the dose of bx at the bottom of bladder is higher than that of the BL reference point, thus minor influence of different bladder states is exerted on the dose level in bladder.