Akira Fujimori

Clinical outcome of stereotactic body radiotherapy of 54 Gy in nine fractions for patients with localized lung tumor using a custom-made immobilization system

PurposeThe aim of this study was to investigate the clinical outcome of stereotactic body radiotherapy (SBRT) of 54u2009Gy in nine fractions for patients with localized lung tumor using a custom-made immobilization system.Methods and materialsThe subjects were 19 patients who had localized lung tumor (11 primaries, 8 metastases) between May 2003 and October 2005. Treatment was conducted on 19 lung tumors by fixed multiple noncoplanar conformal beams with a standard linear accelerator. The isocentric dose was 54u2009Gy in nine fractions. The median overall treatment time was 15 days (range 11–22 days). All patients were immobilized by a thermo-shell and a custom-made headrest during the treatment.ResultsThe crude local tumor control rate was 95% during the follow-up of 9.4–39.5 (median 17.7) months. In-field recurrence was noted in only one patient at the last follow-up. The Kaplan-Meier overall survival rate at 2 years was 89.5%. Grade 1 radiation pneumonia and grade 1 radiation fibrosis were observed in 12 of the 19 patients. Treatment-related severe early and late complications were not observed in this series.ConclusionThe stereotactic body radiotherapy of 54u2009Gy in nine fractions achieved acceptable tumor control without any severe complications. The results suggest that SBRT can be one of the alternatives for patients with localized lung tumors.

Characteristic features of a high-energy x-ray spectra estimation method based on the Waggener iterative perturbation principle.

We have redeveloped a high-energy x-ray spectra estimation method reported by Iwasaki et al. [A. Iwasaki, H. Matsutani, M. Kubota, A. Fujimori, K. Suzaki, and Y. Abe, Radiat. Phys. Chem. 67, 81-91 (2003)]. The method is based on the iterative perturbation principle to minimize differences between measured and calculated transmission curves, originally proposed by Waggener et al. [R. G. Waggener, M. M. Blough, J. A. Terry, D. Chen, N. E. Lee, S. Zhang, and W. D. McDavid, Med. Phys. 26, 1269-1278 (1999)]. The method can estimate spectra applicable for media at least from water to lead using only about ten energy bins. Estimating spectra of 4-15 MV x-ray beams from a linear accelerator, we describe characteristic features of the method with regard to parameters including the prespectrum, number of transmission measurements, number of energy bins, energy bin widths, and artifactual bipeaked spectrum production.

A practical method for estimating high-energy X-ray spectra using the iterative perturbation principle proposed by Waggener

Abstract We have remodeled the X-ray spectra estimation method, originally proposed by Waggener et al. (Med. Phys. 26(1999)1269), based on the iterative perturbation technique to minimize differences between measured and calculated transmission curves using low Z attenuators. With our approach, the iterative perturbation cycle is repeated until a reasonable spectrum is obtained. Furthermore, the degree of differences between the measured and calculated transmission curves is also checked using high Z attenuators. The present experimental study, conducted using 4, 10 and 15xa0MV X-ray beams from a linear accelerator, demonstrated that the spectrum varies strongly with the off-axis distance.