title: Marginal prescription equivalent to the isocenter prescription in lung stereotactic body radiotherapy: preliminary study for Japan Clinical Oncology Group trial (JCOG1408).
abstract: A new randomized Phase III trial, the Japan Clinical Oncology Group (JCOG) 1408, which compares two dose fractionations (JCOG 0403 and JCOG 0702) for medically inoperable Stage IA NSCLC or small lung lesions clinically diagnosed as primary lung cancer, involves the introduction of a prescribed dose to the D95%of the planning target volume (PTV) using a superposition/convolution algorithm. Therefore, we must determine the prescribed dose in the D95%prescribing method to begin JCOG1408. JCOG 0702 uses density correction and the D95%prescribing method. However, JCOG 0403 uses no density correction and isocenter- prescribing method. The purpose of this study was to evaluate the prescribed dose to the D95%of the PTV equivalent to a dose of 48 Gy to the isocenter (JCOG 0403) using a superposition algorithm. The peripheral isodose line, which has the highest conformity index, and the D95%of the PTV were analyzed by considering the weighting factor, i.e. the inverse of the difference between the doses obtained using the superposition and Clarkson algorithms. The average dose at the isodose line of the highest conformity index and the D95%of the PTV were 41.5 ± 0.3 and 42.0 ± 0.3 Gy, respectively. The D95%of the PTV had a small correlation with the target volume (r2= 0.0022) and with the distance between the scatterer and tumor volumes (r2= 0.19). Thus, the prescribed dose of 48 Gy using the Clarkson algorithm (JCOG0403) was found to be equivalent to the prescribed dose of 42 Gy to the D95%of the PTV using the superposition algorithm.
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.|Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kawahara
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan ozawa@hiroshima-u.ac.jp.|Hiroshima High-Precision Radiotherapy Cancer Center, 3-2-2, Futabanosato, Higashi-ku, Hiroshima 732-0057, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Ozawa
authors.affiliation: Department of Radiation Oncology, Hiroshima University Hospital , 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kimura
authors.affiliation: Department of Radiation Oncology, Hiroshima University Hospital , 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Akito
authors.initials: A
authors.lastname: Saito
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Teiji
authors.initials: T
authors.lastname: Nishio
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Nakashima
authors.affiliation: Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Murakami
authors.affiliation: Department of Radiation Oncology, Institute of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan.|Hiroshima High-Precision Radiotherapy Cancer Center, 3-2-2, Futabanosato, Higashi-ku, Hiroshima 732-0057, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nagata
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007564:Japan; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008495:Medical Oncology; D008875:Middle Aged; D016634:Radiosurgery; D047368:Tumor Burden
keywords: Clarkson algorithm; D95%
  ; SBRT; superposition algorithm