Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan.
Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan.
Phys Med. 2018 Jan;45:1-5. doi: 10.1016/j.ejmp.2017.11.018. Epub 2017 Dec 1.
To propose a geometrical margin for definition of the vaginal cuff PTV using only CT images of the full bladder (CT) in postoperative cervical cancer patients.
Twenty-nine operated cervical cancer patients underwent volumetric arc therapy with a bladder filling protocol. This study assessed bladder filling using a portable bladder scanner and cone-beam computed tomography (CBCT) during the entire treatment period. The measured bladder volumes with a BladderScan® were compared with the delineated volume on CBCT. Titanium clips in the vaginal cuff were analysed to assess geometrical uncertainty and the influence of rectal and bladder volume changes.
BladderScan® showed good agreement with the delineated volume (R = 0.80). The volume changes in the bladder have a greater influence on the clip displacements than in the rectum. The 95th percentile of uncertainty of the clips in reference to CT in the right-left (RL), the superoinferior (SI), and the anteroposterior (AP) was 0.32, 0.65, and 1.15 cm, respectively. From this result and intra-fractional movements of the vaginal cuff reported by Haripotepornkul, a new geometrical margin was proposed for definition of the vaginal cuff planning target volume (PTV): 0.5, 0.9, and 1.4 cm in the RL, SI, and AP directions, respectively.
A new geometrical margin was proposed for definition of the vaginal cuff PTV based on CT, which will be needless of empty bladder at the planning CT scan. This method allows patients to reduce the burden and efficient routine CT scans can be improved.
仅使用术后宫颈癌患者的全膀胱 CT 图像，提出一种用于定义阴道残端 PTV 的几何边界。
29 例接受容积弧形治疗且膀胱充盈方案的宫颈癌术后患者参与了此项研究。本研究通过便携式膀胱扫描仪和锥形束 CT（CBCT）在整个治疗期间评估膀胱充盈情况。用 BladderScan® 测量的膀胱体积与 CBCT 上勾画的体积进行比较。分析阴道残端中的钛夹，以评估几何不确定性以及直肠和膀胱体积变化的影响。
BladderScan®与勾画的体积具有很好的一致性（R=0.80）。膀胱体积的变化对夹片位移的影响大于直肠。夹片在 CT 参考系中的左右（RL）、上下（SI）和前后（AP）方向上的不确定性 95%分位数分别为 0.32、0.65 和 1.15cm。根据这一结果以及 Haripotepornkul 报告的阴道残端的分次内运动，为定义阴道残端计划靶区（PTV）提出了新的几何边界：在 RL、SI 和 AP 方向上分别为 0.5、0.9 和 1.4cm。
提出了一种新的基于 CT 的阴道残端 PTV 定义的几何边界，该边界在计划 CT 扫描时无需排空膀胱。该方法可减轻患者负担，并可提高有效的常规 CT 扫描。
