Department of Radiation Oncology, Elekta, Maryland Heights, MO, USA.
Int J Radiat Oncol Biol Phys. 2012 Mar 15;82(4):1439-44. doi: 10.1016/j.ijrobp.2011.05.003. Epub 2011 Jun 22.
To quantify the extent of interfractional vaginal cuff movement in patients receiving postoperative irradiation for cervical or endometrial cancer in the absence of bowel/bladder instruction.
Eleven consecutive patients with cervical or endometrial cancer underwent placement of three gold seed fiducial markers in the vaginal cuff apex as part of standard of care before simulation. Patients subsequently underwent external irradiation and brachytherapy treatment based on institutional guidelines. Daily megavoltage CT imaging was performed during each external radiation treatment fraction. The daily positions of the vaginal apex fiducial markers were subsequently compared with the original position of the fiducial markers on the simulation CT. Composite dose-volume histograms were also created by summing daily target positions.
The average (± standard deviation) vaginal cuff movement throughout daily pelvic external radiotherapy when referenced to the simulation position was 16.2 ± 8.3 mm. The maximum vaginal cuff movement for any patient during treatment was 34.5 mm. In the axial plane the mean vaginal cuff movement was 12.9 ± 6.7 mm. The maximum vaginal cuff axial movement was 30.7 mm. In the craniocaudal axis the mean movement was 10.3 ± 7.6 mm, with a maximum movement of 27.0 mm. Probability of cuff excursion outside of the clinical target volume steadily dropped as margin size increased (53%, 26%, 4.2%, and 1.4% for 1.0, 1.5, 2.0, and 2.5 cm, respectively.) However, rectal and bladder doses steadily increased with larger margin sizes.
The magnitude of vaginal cuff movement is highly patient specific and can impact target coverage in patients without bowel/bladder instructions at simulation. The use of vaginal cuff fiducials can help identify patients at risk for target volume excursion.
在没有肠道/膀胱指导的情况下，定量研究宫颈癌或子宫内膜癌术后接受放射治疗的患者阴道残端在分次间的运动程度。
11 例宫颈癌或子宫内膜癌患者在模拟定位前常规接受 3 枚金制标志点植入阴道残端顶端。随后，患者根据机构指南接受外照射和近距离治疗。在每次外照射治疗期间，每天都要进行兆伏 CT 成像。随后将阴道顶端标志点的每日位置与模拟 CT 上的原始位置进行比较。通过对每日靶区位置进行求和，还创建了复合剂量-体积直方图。
参考模拟位置，在整个盆腔外放射治疗期间，阴道残端的平均（±标准差）移动距离为 16.2±8.3mm。治疗过程中任何患者的最大阴道残端移动距离为 34.5mm。在轴位，阴道残端的平均移动距离为 12.9±6.7mm。最大阴道残端轴向移动距离为 30.7mm。在头脚轴，平均移动距离为 10.3±7.6mm，最大移动距离为 27.0mm。随着边缘大小的增加，残端外扩的概率逐渐下降（1.0cm、1.5cm、2.0cm 和 2.5cm 时的概率分别为 53%、26%、4.2%和 1.4%）。然而，直肠和膀胱剂量随着边缘尺寸的增加而稳定增加。
阴道残端的运动幅度具有高度的个体差异性，在模拟定位时没有肠道/膀胱指导的患者可能会影响靶区的覆盖。阴道残端标志点的使用可以帮助识别有靶区外扩风险的患者。
