Increasing rectum–prostate distance using a hydrogel spacer to reduce radiation exposure during proton beam therapy for prostate cancer. - Narukawa, Tsukasa; Aibe, Norihiro; Tsujimoto, Masashi; Shiraishi, Takumi; Kimoto, Takuya; Suzuki, Gen; Ueda, Takashi; Fujihara, Atsuko; Yamazaki, Hideya; Ukimura, Osamu (Scientific Reports, 2023)