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| 宫颈癌调强放疗中膀胱状态对靶区及危及器官影响 |
| Impacts of bladder status on target volume and OAR in intensity-modulated radiotherapy for cervical cancer |
| 投稿时间：2015-01-16 修订日期：2015-03-20 |
| DOI：10.3969/j.issn.1000-0399.2015.06.005 |
| 中文关键词: 宫颈癌 调强放疗 膀胱状态 剂量学 位移 |
| 英文关键词: Cervical cancer Intensity-modulated radiotherapy Bladder status Dosimetry Shifts |
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| 中文摘要: |
| 目的 研究宫颈癌调强放疗中膀胱不同状态对靶区及危及器官(OAR)的影响, 根据靶区位移的大小初步推断内靶区的大致范围。方法 选择7例无严重合并症的局部晚期初治宫颈癌患者, CT定位时分别在膀胱充盈和排空状态下行2次全盆腔CT扫描, 将获得的CT图像传输至治疗计划系统后, 为每位患者勾画临床靶区(CTV)及OAR, 在规定CTV至少达到95%处方剂量的前提下, 由物理师设计治疗计划。测量2个计划的靶区及OAR剂量学参数和选定径线长度, 并进行统计分析。结果 膀胱不同状态的2个计划中, CTV最大剂量、平均剂量和适形指数差异无统计学意义(P>0.05), 膀胱本身的体积和剂量学参数差异颇大, 直肠部分剂量学参数差异有统计学意义(P<0.05), 膀胱充盈状态下剂量学参数更优。膀胱状态不同可使靶区产生明显位移, 宫底位移在头脚、前后和左右方向上分别为 1.33、0.67和0.60 cm, 在宫颈为1.18、0.63和0.49 cm, 在靶区质心为0.61、0.46和0.28 cm。膀胱体积变化和靶区质心前后位移之间具有很强的相关性(r=0.843, P<0.05)。结论 宫颈癌患者调强放疗时采用膀胱充盈状态对OAR的保护性更好, 应尽量保持分次外照射过程中膀胱状态的一致性。CTV的外放采用头脚方向稍大、宫底范围大于宫颈的锥形外放更为合理。 |
| 英文摘要: |
| Objective To study the impacts of bladder status on the target volume and organs at risk(OAR) in intensity-modulated radiotherapy(IMRT) for cervical cancer, and to determine the margin of the internal target volume(ITV) preliminarily according to the size of the shift of the target volume. Methods Seven locally advanced cervical cancer patients without serious complications who were initially treated with IMRT were selected for this study. All the patients underwent CT scans of the whole pelvic two times in bladder filling status( the bladder was emptied two hours before orientation, then drinking water 500 mL)and empty status to obtain two series of pelvic CT images. The CT images were transferred to the three-dimensional treatment planning system (TPS), contoured the clinical target volume (CTV) and rectum, bladder, spinal cord, etc. for each patient. The treatment planning was performed by the physicist with the CTV reaching at least 95% of the prescription dose. The dosimetric parameters of the target volume and OAR in two different bladder status and the length of the selected lines were measured, and the data were analysed by paired t-test. Results In the two plans of different bladder status, maximum dose, mean dose and conformal index had no difference statistically significantly(P>0.05), and dosimetric parameters of the bladder itself and part of dosimetric parameters of the rectum (P<0.05) had statistical significantly difference, with bladder filling state better. Bladder status could lead to significant shifts of target volume, the shift in superior and inferior, anterior and posterior, left and right direction of fundus was 1.33 cm, 0.67 cm and 0.6 cm respectively, in cervical was 1.18 cm, 0.63 cm and 0.49 cm, in target volume center was 0.61 cm, 0.46 cm and 0.28 cm. Volume changes of bladder and the shifts of the anterior and posterior direction of the target volume had a strong positive correlation (r=0.843, P<0.05). Conclusion For the cervical cancer patients treated with IMRT, bladder filling status is favorable for the protection of OAR and it is recommended to keep the bladder status consistently between fractionated external beam radiotherapy. It is more reasonable to make the CTV margin bigger in superior and inferior direction and the fundus of uterus. |
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