Search

Your search keyword '"Takayanagi, T."' showing total 39 results
Start Over Author "Takayanagi, T." Publisher iop publishing
39 results on '"Takayanagi, T."'

11. Improvement of beam performance in the negative-ion based NBI system for JT-60U

Author

Umeda, N, primary, Grisham, L.R, additional, Yamamoto, T, additional, Kuriyama, M, additional, Kawai, M, additional, Ohga, T, additional, Mogaki, K, additional, Akino, N, additional, Yamazaki, H, additional, Usui, K, additional, Honda, A, additional, Guangjiu, L, additional, Watanabe, K, additional, Inoue, T, additional, Hanada, M, additional, Kashiwagi, M, additional, Morishita, T, additional, Dairaku, M, additional, and Takayanagi, T, additional

Published
2003
Full Text
View/download PDF

21. Ejected-electron spectra from the triplet states of O4+(1s23l3l') produced by O6++O2collisions

Author

Nakamura, N, primary, Nabeshima, T, additional, Currell, F J, additional, Kanai, Y, additional, Kitazawa, S, additional, Koide, M, additional, Sakaue, H A, additional, Ida, H, additional, Matsui, Y, additional, Wakiya, K, additional, Takayanagi, T, additional, Kambara, T, additional, Awaya, Y, additional, Suzuki, H, additional, Ohtani, S, additional, and Safronova, U I, additional

Published
1994
Full Text
View/download PDF

37. Development and evaluation of a short-range applicator for treating superficial moving tumors with respiratory-gated spot-scanning proton therapy using real-time image guidance.

Author

Matsuura T, Fujii Y, Takao S, Yamada T, Matsuzaki Y, Miyamoto N, Takayanagi T, Fujitaka S, Shimizu S, Shirato H, and Umegaki K

Subjects
Fiducial Markers, Humans, Lung Neoplasms diagnostic imaging, Motion, Proton Therapy methods, Proton Therapy standards, Radiotherapy Dosage, Radiotherapy, Computer-Assisted methods, Radiotherapy, Computer-Assisted standards, Fluoroscopy methods, Lung Neoplasms radiotherapy, Proton Therapy instrumentation, Radiotherapy, Computer-Assisted instrumentation, Respiration
Abstract

Treatment of superficial tumors that move with respiration (e.g. lung tumors) using spot-scanning proton therapy (SSPT) is a high-priority research area. The recently developed real-time image-gated proton beam therapy (RGPT) system has proven to be useful for treating moving tumors deep inside the liver. However, when treating superficial tumors, the proton's range is small and so is the sizes of range straggling, making the Bragg-peaks extremely sharp compared to those located in deep-seated tumors. The extreme sharpness of Bragg-peaks is not always beneficial because it necessitates a large number of energy layers to make a spread-out Bragg-peak, resulting in long treatment times, and is vulnerable to motion-induced dose deterioration. We have investigated a method to treat superficial moving tumors in the lung by the development of an applicator compatible with the RGPT system. A mini-ridge filter (MRF) was developed to broaden the pristine Bragg-peak and, accordingly, decrease the number of required energy layers to obtain homogeneous irradiation. The applicator position was designed so that the fiducial marker's trajectory can be monitored by fluoroscopy during proton beam-delivery. The treatment plans for three lung cancer patients were made using the applicator, and four-dimensional (4D) dose calculations for the RGPT were performed using patient respiratory motion data. The effect of the MRF on the dose distributions and treatment time was evaluated. With the MRF, the number of energy layers was decreased to less than half of that needed without it, whereas the target volume coverage values (D99%, D95%, D50%, D2%) changed by less than 1% of the prescribed dose. Almost no dose distortion was observed after the 4D dose calculation, whereas the treatment time decreased by 26%-37%. Therefore, we conclude that the developed applicator compatible with RGPT is useful to solve the issue in the treatment of superficial moving tumors with SSPT.

Published
2016
Full Text
View/download PDF

38. Design of a ridge filter structure based on the analysis of dose distributions.

Author

Fujimoto R, Takayanagi T, and Fujitaka S

Subjects
Equipment Design, Equipment Failure Analysis, Radiotherapy Dosage, Reproducibility of Results, Scattering, Radiation, Sensitivity and Specificity, Computer-Aided Design, Filtration instrumentation, Radiotherapy, Conformal instrumentation
Abstract

Dose distributions distorted by a periodic structure, such as a ridge filter, are analytically investigated. Based on the beam optics, the fluence distributions of scanned beams passing through the ridge filter are traced. It is shown that the periodic lateral dose distribution blurred by multiple Coulomb scattering can be expressed by a sum of cosine functions through Fourier transform. The result shows that the dose homogeneity decreases exponentially as the period of the structure becomes longer. This analysis is applied to the example case of a mini-ridge filter. The mini-ridge filter is designed to broaden sharp Bragg peaks for an energy-stacking irradiation method. The dose distributions depend on the period of the ridge filter structure and the angular straggling at the ridge filter position. Several cases are prepared where the period and angular straggling are supposed to be probable values. In these cases, the lateral distributions obtained by the analytical method are compared to Monte Carlo simulation results. Both distributions show good agreement with each other within 1%, which means that this analysis allows estimation of the dose distribution downstream of the ridge filter quantitatively. The appropriate period of grooves and scatterer width can be determined which ensures sufficient homogeneity.

Published
2009
Full Text
View/download PDF

39. Reduction of the number of stacking layers in proton uniform scanning.

Author

Fujitaka S, Takayanagi T, Fujimoto R, Fujii Y, Nishiuchi H, Ebina F, Okazaki T, Hiramoto K, Sakae T, and Terunuma T

Subjects
Computer-Aided Design, Equipment Design, Equipment Failure Analysis, Radiotherapy Dosage, Reproducibility of Results, Scattering, Radiation, Sensitivity and Specificity, Filtration instrumentation, Proton Therapy, Radiotherapy, Conformal instrumentation
Abstract

Uniform scanning with a relatively large beam size can improve beam utilization efficiency more than conventional irradiation methods using scatterers and can achieve a large-field, long-range and large spread-out Bragg peak (SOBP). The SOBP is obtained by energy stacking in uniform scanning, but its disadvantage is that the number of stacking layers is large, especially in the low-energy region, because the Bragg peak of the pristine beam is very sharp. We applied a mini-ridge filter to broaden the pristine Bragg peak up to a stacked layer thickness of 1 or 2 cm in order to decrease the number of stacking layers. The number of stacking layers can be reduced to 20% or less than that in the case of pristine beam stacking. Although the distal falloff of the SOBP is deteriorated by applying the mini-ridge filter, we can improve the distal falloff to that of pristine beam stacking by introducing the distal filter to the irradiation of the most distal layer. Uniform scanning in combination with mini-ridge filter use can more than double the beam utilization efficiency over that of passive irradiation techniques.

Published
2009
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results