Spacers for radiotherapy which are compatible with flexibility to gently coat along organs of various shapes and pressure resistance for maintaining the shape without collapsing even if pressure between the organs is loaded and pressure space Has been disclosed. The spacer includes a fiber aggregate such as a nonwoven fabric in which biocompatible fibers which may be bioabsorbable are entangled, and the density of the fiber aggregate is 0.05 g / cm3~ 0.2 g / cm3様々な形状の臓器に沿って優しく覆うための柔軟性と,臓器間圧力が負荷されても潰れず形状を維持して治療スペースを確保し続けるための耐圧性とを両立させた放射線治療用スペーサーが開示されている。当該スペーサーは,生体吸収性であってよい生体適合性の繊維が交絡した不織布等の繊維集合体を含んでなり,繊維集合体の密度が0.05g/cm3~0.2g/cm3であることを特徴とする。
