Dpt. of Radiation Oncology, St. Johanns-Spital, Paracelsus Medical University of Salzburg, Austria.
Dpt. of Radiation Oncology, St. Johanns-Spital, Paracelsus Medical University of Salzburg, Austria.
Radiother Oncol. 2015 Aug;116(2):221-5. doi: 10.1016/j.radonc.2015.07.027. Epub 2015 Jul 28.
In external beam radiation (EBRT) of the prostate, the rectum is the dose-limiting organ at risk, and sparing of the anterior rectal wall is a prerequisite for safe delivery of doses beyond 70 Gy. Spatial sparing of the rectum can be achieved by introducing a spacer material into the retroprostatic space, thus separating the anterior rectal wall from the PTV.
Two spacer technologies, Spacer OAR, a polyethylene glycol gel and ProSpace, a saline inflated balloon, were compared in terms of spacer volume, stability, and dose reduction to the anterior rectum wall in 78 patients.
Both spacer systems significantly reduced the rectum surface encompassed by the 95% isodose (gel: -35%, p<0.01; balloon -63.4%, p<0.001) compared to a control group. The balloon spacer was superior in reducing rectum dose (-27.7%, p=0.034), but exhibited an average volume loss of >50% during the full course of treatment of 37-40 fractions, while the volume of gel spacers remained fairly constant.
In choosing between the two spacer technologies, the advantageous dose reduction of the balloon needs to be weighed up against the better volume consistency of the gel spacer with respect to the duration of hypofractionated vs normofractionated regimens.
在前列腺的外照射放射治疗（EBRT）中，直肠是剂量限制的危险器官，因此，安全地给予超过 70Gy 的剂量的前提是保护前直肠壁。通过将间隔材料引入前列腺后空间，可以实现直肠的空间保护，从而将前直肠壁与 PTV 分开。
在 78 例患者中，比较了两种间隔技术，即 Spacer OAR（一种聚乙二醇凝胶）和 ProSpace（一种盐水充气气球），比较了间隔体积、稳定性以及对前直肠壁的剂量降低。
与对照组相比，两种间隔系统均显著降低了 95%等剂量线所包绕的直肠表面（凝胶：-35%，p<0.01；气球：-63.4%，p<0.001）。与凝胶间隔器相比，气球间隔器在降低直肠剂量方面具有优势（-27.7%，p=0.034），但在 37-40 个分次的全程治疗过程中，其体积损失平均超过 50%，而凝胶间隔器的体积则保持相当稳定。
在两种间隔技术之间进行选择时，需要权衡气球间隔器的有利剂量降低与凝胶间隔器在短疗程与常规疗程中的体积一致性。
