Quantification of vaginal motion associated with daily endorectal balloon placement during whole pelvis radiotherapy for gynecologic cancers

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• 作者：Nicolette Taku ; Joseph Dise ; Owen Kenton ; Lingshu Yin ; Boon-Keng Kevin Teo ; Lilie L. Lin ; ^{lin@xrt.upenn.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Vaginal movement ; Gynecologic cancer ; External beam radiation ; Endorectal balloon ; Bladder filling
• 刊名：Radiotherapy and Oncology
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：120
• 期：3
• 页码：532-536
• 全文大小：457 K

文摘

To quantify intra-treatment vaginal motion in women treated with daily endorectal balloon (ERB) placement and external beam radiotherapy for gynecologic cancers.

Materials and methods

Eighteen post-hysterectomy women with gynecologic cancers underwent computed tomography (CT) simulation scans and daily treatment with ERB. Fiducial markers were placed at the vaginal apex prior to simulation and patients were counseled on a pre-treatment bladder filling protocol. Weekly to biweekly verification CT scans were used to calculate the intra-treatment change in bladder volumes, rectal volumes, and fiducial coordinates along all axes. The planning target volume (PTV) margins required to encompass 95% of intra-treatment fiducial movement were calculated using the van Herk margin recipe.

Results

The median bladder volume was 223 (range, 29–879) cc for verification CT scans. Mean intra-treatment fiducial displacements were 1.7 (range, 0–9.1) mm, 2.9 (range, 0–15.5) mm, and 2.5 (range, 0–11.8) mm along the left–right (L/R), superior–inferior (S/I), and anterior–posterior (A/P) axes, respectively. The van Herk PTV margins were 3 mm (L/R), 10 mm (S/I) and 7 mm (A/P).

Conclusion

When compared to existing studies, the use of daily ERB with post-hysterectomy radiotherapy reduces vaginal motion along the A/P axis. The impact of variable bladder filling on vaginal motion is most evident along the S/I axis.