Spacer stability and prostate position variability during radiotherapy for prostate cancer applying a hydrogel to protect the rectal wall

作者：Pinkawa Michael^*; Piroth Marc D; Holy Richard; Escobar Corral Nuria; Caffaro Mariana; Djukic Victoria; Klotz Jens; Eble Michael J

来源：Radiotherapy and Oncology, 2013, 106(2): 220-224.

DOI：10.1016/j.radonc.2012.11.010

• Prostate neoplasm
• Conformal radiotherapy
• Intensity-modulated radiotherapy
• Treatment planning
• Toxicity
• Spacer gel

Background and purpose: The aim was to evaluate the spacer dimensions and prostate position variability during the course of radiotherapy for prostate cancer. %26lt;br%26gt;Materials and methods: CT scans were performed in a group of 15 patients (G1) after the 10 ml injection of a hydrogel spacer (SpaceOAR (TM)) and 30 patients without a spacer (G2) before the beginning of treatment (CT1) and in the last treatment week, 10-12 weeks following spacer implantation (CT2). Spacer dimensions and displacements were determined and Prostate displacements compared. %26lt;br%26gt;Results: Mean volume of the hydrogel increased slightly (17%; p %26lt; 0.01), in 4 of 15 patients %26gt;2 cm(3). The average displacement of the hydrogel center of mass was 0.6 mm (87% %26lt;= 2.2 mm), 0.6 mm (100% %26lt;= 2.2 mm) and 1.4 mm (87% %26lt;= 4.3 mm) in the x-, y- and z-axes (not significant). The average distance between prostate and anterior rectal wall before/at the end of radiotherapy was 1.6 cm/1.5 cm, 1.2 cm/1.3 cm and 1.0 cm/1.1 cm at the level of the base, middle and apex (G1). Prostate position variations were similar comparing G1 and G2, but significant systematic posterior displacements were only found in G2. %26lt;br%26gt;Conclusions: A stable distance between the prostate and anterior rectal wall results during the radiotherapy course after injection of the spacer before treatment planning. Larger posterior prostate displacements could be reduced.

• 出版日期2013-2