**Author details**

**Figure 3.** Microscopic features of the PGA bioabsorbable spacer implanted in the rat abdomen. In the surface of the PGA spacer, inflammatory response was observed. There were degraded PGA fibers, lymphocyte, and macrophage observed in the surface. Interestingly, very few cell infiltrations were observed in the body of the PGA spacer

Although there is no clear definition of a bioabsorbable nonwoven fabric spacer reported, an optimal bioabsorbable spacer must have thickness-retaining and water-equivalency properties according to treatment duration [19]. In particle therapies, because treatment protocols take 2–7 weeks [5, 33], a spacer that maintains its thickness for the duration of or slightly longer than the treatment period seems to be ideal. From our investigation, the percentage of thickness retention of the PGA spacer varies according to the concentration of the PGA sutures. The PGA

Therefore, this PGA spacer could be applied in various protocols in particle therapy. The bioabsorbable PGA spacer might become a useful device and expand indications for particle

**5. Future direction of medical application of bioabsorbable nonwoven**

Adhesions after surgery might lead to serious complications [34, 35]. In the pelvic and abdominal sites, these complications might lead to small-bowel obstruction, infertility, chronic

of PGA sutures retains more than 90% thickness for 8 weeks.

spacer product with 0.2 g/cm3

therapy.

210 Non-woven Fabrics

**fabric spacers**

Ryohei Sasaki1\*, Hiroaki Akasaka1 , Yusuke Demizu2 , Sachiko Inubushi1 , Tianyuan Wang1 and Takumi Fukumoto1

\*Address all correspondence to: rsasaki@med.kobe-u.ac.jp

1 Divisions of Radiation Oncology and of Hepato-Biliary-Pancreas Surgery, Kobe University Graduate School of Medicine, Kobe City, Hyogo, Japan

2 Department of Radiology, Hyogo Ion Beam Medical Center, Hyogo, Japan
