title: Dose Evaluation of Fractionated Schema and Distance From Tumor to Spinal Cord for Spinal SBRT with Simultaneous Integrated Boost: A Preliminary Study.
abstract: BACKGROUND This study investigated and quantified the dosimetric impact of the distance from the tumor to the spinal cord and fractionation schemes for patients who received stereotactic body radiation therapy (SBRT) and hypofractionated simultaneous integrated boost (HF-SIB). MATERIAL AND METHODS Six modified planning target volumes (PTVs) for 5 patients with spinal metastases were created by artificial uniform extension in the region of PTV adjacent spinal cord with a specified minimum tumor to cord distance (0-5 mm). The prescription dose (biologic equivalent dose, BED) was 70 Gy in different fractionation schemes (1, 3, 5, and 10 fractions). For PTV V100, Dmin, D98, D95, and D1, spinal cord dose, conformity index (CI), V30 were measured and compared. RESULTS PTV-to-cord distance influenced PTV V100, Dmin, D98, and D95, and fractionation schemes influenced Dmin and D98, with a significant difference. Distances of ≥2 mm, ≥1 mm, ≥1 mm, and ≥0 mm from PTV to spinal cord meet dose requirements in 1, 3, 5, and 10 fractionations, respectively. Spinal cord dose, CI, and V30 were not impacted by PTV-to-cord distance and fractionation schemes. CONCLUSIONS Target volume coverage, Dmin, D98, and D95 were directly correlated with distance from the spinal cord for spine SBRT and HF-SIB. Based on our study, ≥2 mm, ≥1 mm, ≥1 mm, and ≥0 mm distance from PTV to spinal cord meets dose requirements in 1, 3, 5 and 10 fractionations, respectively.
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Hao
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Bo-ning
authors.initials: BN
authors.lastname: Cai
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Xiao-shen
authors.initials: XS
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Xiao-hu
authors.initials: XH
authors.lastname: Cong
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Jin-yuan
authors.initials: JY
authors.lastname: Wang
authors.affiliation: Department of Oncology, First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan, China (mainland).
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Shou-ping
authors.initials: SP
authors.lastname: Xu
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Zhong-jian
authors.initials: ZJ
authors.lastname: Ju
authors.affiliation: Department of Radiation Oncology, Chinese PLA General Hospital, Beijing, China (mainland).
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
mesh_terms: D019583:Dose Fractionation, Radiation; D006801:Humans; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D013116:Spinal Cord / Q000000981:diagnostic imaging* / Q000601:surgery*; D013120:Spinal Cord Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*