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Your search keyword '"Miyazaki, Masayoshi"' showing total 9 results
Start Over Author "Miyazaki, Masayoshi" Journal journal of radiation research
9 results on '"Miyazaki, Masayoshi"'

1. Dual-energy computed tomography-based iodine concentration as a predictor of histopathological response to preoperative chemoradiotherapy for pancreatic cancer

Author

Ohira, Shingo, primary, Ikawa, Toshiki, additional, Kanayama, Naoyuki, additional, Minamitani, Masanari, additional, Kihara, Sayaka, additional, Inui, Shoki, additional, Ueda, Yoshihiro, additional, Miyazaki, Masayoshi, additional, Yamashita, Hideomi, additional, Nishio, Teiji, additional, Koizumi, Masahiko, additional, Nakagawa, Keiichi, additional, and Konishi, Koji, additional

Published
2023
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4. Intra-fractional patient setup error during fractionated intracranial stereotactic irradiation treatment of patients wearing medical masks: comparison with and without bite block during COVID-19 pandemic

Author

Ohira, Shingo, primary, Kanayama, Naoyuki, additional, Komiyama, Riho, additional, Ikawa, Toshiki, additional, Toratani, Masayasu, additional, Ueda, Yoshihiro, additional, Washio, Hayate, additional, Miyazaki, Masayoshi, additional, Koizumi, Masahiko, additional, and Teshima, Teruki, additional

Published
2020
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5. Intra-fractional patient setup error during fractionated intracranial stereotactic irradiation treatment of patients wearing medical masks: comparison with and without bite block during COVID-19 pandemic.

Author

Ohira, Shingo, Kanayama, Naoyuki, Komiyama, Riho, Ikawa, Toshiki, Toratani, Masayasu, Ueda, Yoshihiro, Washio, Hayate, Miyazaki, Masayoshi, Koizumi, Masahiko, and Teshima, Teruki

Subjects
COVID-19 pandemic, MEDICAL masks
Abstract

The immobilization of patients with a bite block (BB) carries the risk of interpersonal infection, particularly in the context of pandemics such as COVID-19. Here, we compared the intra-fractional patient setup error (intra-SE) with and without a BB during fractionated intracranial stereotactic irradiation (STI). Fifteen patients with brain metastases were immobilized using a BB without a medical mask, while 15 patients were immobilized without using a BB and with a medical mask. The intra-SEs in six directions (anterior–posterior (AP), superior–inferior (SI), left–right (LR), pitch, roll, and yaw) were calculated by using cone-beam computed tomography images acquired before and after the treatments. We analyzed a total of 53 and 67 treatment sessions for the with- and without-BB groups, respectively. A comparable absolute mean translational and rotational intra-SE was observed (P  > 0.05) in the AP (0.19 vs 0.23 mm with- and without-BB, respectively), SI (0.30 vs 0.29 mm), LR (0.20 vs 0.29 mm), pitch (0.18 vs 0.27°), roll (0.23 vs 0.23°) and yaw (0.27 vs 22°) directions. The resultant planning target volume (PTV) margin to compensate for intra-SE was <1 mm. No statistically significant correlation was observed between the intra-SE and treatment times. A PTV margin of <1 mm was achieved even when patients were immobilized without a BB during STI dose delivery. [ABSTRACT FROM AUTHOR]

Published
2021
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6. Can clinically relevant dose errors in patient anatomy be detected by gamma passing rate or modulation complexity score in volumetric-modulated arc therapy for intracranial tumors?

Author

Ohira, Shingo, primary, Ueda, Yoshihiro, additional, Isono, Masaru, additional, Masaoka, Akira, additional, Hashimoto, Misaki, additional, Miyazaki, Masayoshi, additional, Takashina, Masaaki, additional, Koizumi, Masahiko, additional, and Teshima, Teruki, additional

Published
2017
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8. VMAT–SBRT planning based on an average intensity projection for lung tumors located in close proximity to the diaphragm: a phantom and clinical validity study

Author

Ohira, Shingo, primary, Ueda, Yoshihiro, additional, Hashimoto, Misaki, additional, Miyazaki, Masayoshi, additional, Isono, Masaru, additional, Kamikaseda, Hiroshi, additional, Masaoka, Akira, additional, Takashina, Masaaki, additional, Koizumi, Masahiko, additional, and Teshima, Teruki, additional

Published
2015
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9. VMAT-SBRT planning based on an average intensity projection for lung tumors located in close proximity to the diaphragm: a phantom and clinical validity study

Author

Ohira, Shingo, Ueda, Yoshihiro, Hashimoto, Misaki, Miyazaki, Masayoshi, Isono, Masaru, Kamikaseda, Hiroshi, Masaoka, Akira, Takashina, Masaaki, Koizumi, Masahiko, and Teshima, Teruki

Abstract

The aim of the this study was to validate the use of an average intensity projection (AIP) for volumetric-modulated arc therapy for stereotactic body radiation therapy (VMAT–SBRT) planning for a moving lung tumor located near the diaphragm. VMAT–SBRT plans were created using AIPs reconstructed from 10 phases of 4DCT images that were acquired with a target phantom moving with amplitudes of 5, 10, 20 and 30 mm. To generate a 4D dose distribution, the static dose for each phase was recalculated and the doses were accumulated by using the phantom position known for each phase. For 10 patients with lung tumors, a deformable registration was used to generate 4D dose distributions. Doses to the target volume obtained from the AIP plan and the 4D plan were compared, as were the doses obtained from each plan to the organs at risk (OARs). In both phantom and clinical study, dose discrepancies for all parameters of the dose volume (Dmin, D99, Dmax, D1 and Dmean) to the target were <3%. The discrepancies of Dmax for spinal cord, esophagus and heart were <1 Gy, and the discrepancy of V20 for lung tissue was <1%. However, for OARs with large respiratory motion, the discrepancy of the Dmax was as much as 9.6 Gy for liver and 5.7 Gy for stomach. Thus, AIP is clinically acceptable as a planning CT image for predicting 4D dose, but doses to the OARs with large respiratory motion were underestimated with the AIP approach.

Published
2016
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