BACKGROUND AND PURPOSE: The aim was to evaluate the spacer dimensions and prostate position variability during the course of radiotherapy for prostate cancer.
MATERIALS AND METHODS: CT scans were performed in a group of 15 patients (G1) after the 10ml injection of a hydrogel spacer (SpaceOAR™) and 30 patients without a spacer (G2) before the beginning of treatment (CT1) and in the last treatment week, 10-12weeks following spacer implantation (CT2). Spacer dimensions and displacements were determined and prostate displacements compared.
RESULTS: Mean volume of the hydrogel increased slightly (17%; p< 0.01), in 4 of 15 patients >2cm3. The average displacement of the hydrogel center of mass was 0.6mm (87% ≤ 2.2mm), -0.6mm (100% ≤ 2.2mm) and 1.4mm (87% ≤ 4.3mm) 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 1.6cm/1.5cm, 1.2cm/1.3cm and 1.0cm/1.1cm 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.
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.
Written by:
Pinkawa M, Piroth MD, Holy R, Escobar-Corral N, Caffaro M, Djukic V, Klotz J, Eble MJ. Are you the author?
Department of Radiation Oncology, RWTH Aachen University, Germany.
Reference: Radiother Oncol. 2013 Jan 16. pii: S0167-8140(12)00529-4.
doi: 10.1016/j.radonc.2012.11.010
PubMed Abstract
PMID: 23333015
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