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2. Evaluation of Radiation Doses Received by Physicians during Permanent 198 Au Grain Implant Brachytherapy for Oral Cancer.

Author

Inaba, Yohei, Jingu, Keiichi, Fujisawa, Masaki, Otomo, Kazuki, Ishii, Hiroki, Kato, Toshiki, Murabayashi, Yuuki, Suzuki, Masatoshi, Zuguchi, Masayuki, and Chida, Koichi

Subjects
MEDICAL personnel, RADIATION doses, RADIATION protection, TONGUE cancer, CRYSTALLINE lens
Abstract

Featured Application: Importance of the evaluation of the physician's eye exposure to radiation during 198Au grain brachytherapy, given that the eye dose limit has been reduced drastically from 150 to 20 mSv/year. Brachytherapy is a practical, effective procedure for the local treatment of cancer; it delivers a high radiation dose to a limited tissue volume while sparing the surrounding normal tissues. Although the clinical benefit of brachytherapy is clear, there have been very few studies on the radiation dose received by physicians during the procedure. Furthermore, no study has investigated the eye radiation dose received by physicians performing 198Au grain (seed) brachytherapy, using an eye dosimeter. Recently, the International Commission on Radiological Protection (ICRP) recommended significantly reducing the occupational lens dose limit, from 150 to 20 mSv/yr (100 mSv/5 years). Therefore, it has become essential to evaluate the eye radiation doses of medical workers. We evaluated the eye radiation dose of a brachytherapy physician performing 198Au permanent grain implantation for tongue cancer; this is the first study on this topic. The maximum eye dose was ~0.1 mSv/procedure, suggesting that it is unlikely to exceed the ICRP limit (20 mSv/yr) for the lens, unless many procedures are performed with inappropriate radiation protection. To reduce the dose of radiation received by 198Au grain brachytherapy physicians, it is necessary to use additional lead shielding equipment when preparing the treatment needles, i.e., when loading the grains. This study provides useful information on radiation exposure of physicians conducting 198Au permanent grain brachytherapy. [ABSTRACT FROM AUTHOR]

Published
2024
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3. Effect of backscatter radiation on the occupational eye-lens dose.

Author

Ohno, Saya, Konta, Satoe, Shindo, Ryota, Yamamoto, Keisuke, Isobe, Rio, Inaba, Yohei, Suzuki, Masatoshi, Zuguchi, Masayuki, and Chida, Koichi

Subjects
PROTECTIVE eyeglasses, RADIATION protection, BACKSCATTERING, RADIATION measurements, CRYSTALLINE lens
Abstract

We quantified the level of backscatter radiation generated from physicians' heads using a phantom. We also evaluated the shielding rate of the protective eyewear and optimal placement of the eye-dedicated dosimeter (skin surface or behind the Pb-eyewear). We performed diagnostic X-rays of two head phantoms: Styrofoam (negligible backscatter radiation) and anthropomorphic (included backscatter radiation). Radiophotoluminescence glass dosimeters were used to measure the eye-lens dose, with or without 0.07-mm Pb-equivalent protective eyewear. We used tube voltages of 50, 65 and 80 kV because the scattered radiation has a lower mean energy than the primary X-ray beam. The backscatter radiation accounted for 17.3–22.3% of the eye-lens dose, with the percentage increasing with increasing tube voltage. Furthermore, the shielding rate of the protective eyewear was overestimated, and the eye-lens dose was underestimated when the eye-dedicated dosimeter was placed behind the protective eyewear. We quantified the backscatter radiation generated from physicians' heads. To account for the effect of backscatter radiation, an anthropomorphic, rather than Styrofoam, phantom should be used. Close contact of the dosimeter with the skin surface is essential for accurate evaluation of backscatter radiation from physician's own heads. To assess the eye-lens dose accurately, the dosimeter should be placed near the eye. If the dosimeter is placed behind the lens of the protective eyewear, we recommend using a backscatter radiation calibration factor of 1.2–1.3. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Analysis of whole-blood antioxidant capacity after chronic and localized irradiation using the i-STrap method

Author

Sun, Lue, Inaba, Yohei, Sogo, Yu, Morikawa, Kumi, Kunugita, Naoki, Chida, Koichi, Moritake, Takashi, Naoki, Kunugita, and Takashi, Moritake

Abstract

Ionizing radiation exposure affects the redox state in vivo. Recently, whole-blood antioxidant capacity (WBAC) has been reported to decrease in a dose-dependent manner after acute total body irradiation (TBI). However, changes in WBAC after localized and chronic irradiations have not been reported. This study analyzed changes to WBAC in mice after either localized irradiation (irradiation of the left hind leg only) or chronic TBI using the i-STrap method. Leg-localized irradiation exerted limited effects on WBAC, while WBAC decreased in a dose rate-dependent manner after TBI. Further, the WBAC reached the minimum value in a shorter period at a smaller dose rate. Our results suggest that changes in WBAC do not directly reflect absorbed dose, but may reflect radiation-induced biological damage at the systemic level. This study will contribute to the understanding of radiation-induced injuries and diseases, and will facilitate the establishment of biomarkers for radiation exposure.

Published
2022

13. Internal organ dose rate conversion coefficients of Japanese macaques to 134Cs,137Cs and 131I.

Author

Takamura, Yuta, Kajimoto, Tsuyoshi, Tanaka, Kenichi, Yamamoto, Tomoya, Suzuki, Masatoshi, Inaba, Yohei, Chida, Koichi, Fukumoto, Manabu, Rangacharyulu, Chary, and Endo, Satoru

Abstract

The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10 kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two species. For γ-radiation, there was excellent agreement in the self-absorption rate with the approximate curve of the Japanese macaque, with an average deviation of 2%. The maximum deviation of 12% was for the kidney, which has two organs, so the error with the approximate curve is slightly larger due to the energy loss created between organs. [ABSTRACT FROM AUTHOR]

Published
2023
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21. Evaluation of radiation dose for inferior vena cava filter placement during pregnancy: A comparison of dosimetry and dose calculation software.

Author

Matsunaga, Yuta, Haba, Tomonobu, Kobayashi, Masanao, Suzuki, Shoichi, Asada, Yasuki, and Chida, Koichi

Subjects
VENA cava inferior, IMAGING phantoms, RADIATION doses, RADIATION dosimetry, PREGNANT women, SOFTWARE measurement
Abstract

Numerous medical conditions are associated with pregnancy in women, including pulmonary thromboembolism, which can be fatal. An effective treatment of this condition is the positioning of an inferior vena cava filter (IVC‐F) under the guidance of X‐ray imaging. However, this procedure involves the risk of high radiation exposure to pregnant women and fetuses. Moreover, there are no published reports comparing the values of fetal dose, received during IVC‐F placement in pregnant women, determined using dose calculation software and actual measurements. To address this issue, we compared the fetal radiation dose and entrance surface dose (ESD) for pregnant women for gestation periods of 6 and 9 months based on software calculations and actual measurements. The ESD and fetal doses were estimated for a pregnant woman for gestation periods of 6 and 9 months during IVC‐F placement. For actual measurements, one pregnant model phantom was constructed using an anthropomorphic phantom, and two custom‐made different‐sized abdomen phantoms were used to simulate pregnancy. The custom‐made abdomen phantoms were constructed using polyurethane. For software calculations, the software utilized a set of anatomically realistic pregnant patient phantoms. The ESD estimated using the software was consistent with the measured ESD, but the fetal dose estimations were more complicated due to fetal positioning. During fetal dose evaluation using software calculations, the user must carefully consider how much of the fetal length is in the irradiation field to prevent underestimation or overestimation. Despite the errors, the software can assist the user in identifying the magnitude of the dose approaching critical limits. [ABSTRACT FROM AUTHOR]

Published
2023
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37. Treatment outcome of high-dose image-guided intensity-modulated radiotherapy using intra-prostate fiducial markers for localized prostate cancer at a single institute in Japan

Author

Takeda Ken, Takai Yoshihiro, Narazaki Kakutaro, Mitsuya Masatoshi, Umezawa Rei, Kadoya Noriyuki, Fujita Yukio, Sugawara Toshiyuki, Kubozono Masaki, Shimizu Eiji, Abe Keiko, Shirata Yuko, Ishikawa Yohjiro, Yamamoto Takaya, Kozumi Maiko, Dobashi Suguru, Matsushita Haruo, Chida Koichi, Ishidoya Shigeto, Arai Yoichi, Jingu Keiichi, and Yamada Shogo

Subjects
Image-guided radiotherapy, Prostate cancer, Biochemical control, Toxicity, Medical physics. Medical radiology. Nuclear medicine, R895-920, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282
Abstract

Abstract Background Several studies have confirmed the advantages of delivering high doses of external beam radiotherapy to achieve optimal tumor-control outcomes in patients with localized prostate cancer. We evaluated the medium-term treatment outcome after high-dose, image-guided intensity-modulated radiotherapy (IMRT) using intra-prostate fiducial markers for clinically localized prostate cancer. Methods In total, 141 patients with localized prostate cancer treated with image-guided IMRT (76 Gy in 13 patients and 80 Gy in 128 patients) between 2003 and 2008 were enrolled in this study. The patients were classified according to the National Comprehensive Cancer Network-defined risk groups. Thirty-six intermediate-risk patients and 105 high-risk patients were included. Androgen-deprivation therapy was performed in 124 patients (88%) for a median of 11 months (range: 2–88 months). Prostate-specific antigen (PSA) relapse was defined according to the Phoenix-definition (i.e., an absolute nadir plus 2 ng/ml dated at the call). The 5-year actuarial PSA relapse-free survival, the 5-year distant metastasis-free survival, the 5-year cause-specific survival (CSS), the 5-year overall survival (OS) outcomes and the acute and late toxicities were analyzed. The toxicity data were scored according to the Common Terminology Criteria for Adverse Events, version 4.0. The median follow-up was 60 months. Results The 5-year PSA relapse-free survival rates were 100% for the intermediate-risk patients and 82.2% for the high-risk patients; the 5-year actuarial distant metastasis-free survival rates were 100% and 95% for the intermediate- and high-risk patients, respectively; the 5-year CSS rates were 100% for both patient subsets; and the 5-year OS rates were 100% and 91.7% for the intermediate- and high-risk patients, respectively. The Gleason score ( Conclusions These medium-term results demonstrate a good tolerance of high-dose image-guided IMRT. However, further follow-up is needed to confirm the long-term treatment outcomes.

Published
2012
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44. The Tohoku Medical Megabank Project: Design and Mission

Author

Kuriyama, Shinichi, primary, Yaegashi, Nobuo, additional, Nagami, Fuji, additional, Arai, Tomohiko, additional, Kawaguchi, Yoshio, additional, Osumi, Noriko, additional, Sakaida, Masaki, additional, Suzuki, Yoichi, additional, Nakayama, Keiko, additional, Hashizume, Hiroaki, additional, Tamiya, Gen, additional, Kawame, Hiroshi, additional, Suzuki, Kichiya, additional, Hozawa, Atsushi, additional, Nakaya, Naoki, additional, Kikuya, Masahiro, additional, Metoki, Hirohito, additional, Tsuji, Ichiro, additional, Fuse, Nobuo, additional, Kiyomoto, Hideyasu, additional, Sugawara, Junichi, additional, Tsuboi, Akito, additional, Egawa, Shinichi, additional, Ito, Kiyoshi, additional, Chida, Koichi, additional, Ishii, Tadashi, additional, Tomita, Hiroaki, additional, Taki, Yasuyuki, additional, Minegishi, Naoko, additional, Ishii, Naoto, additional, Yasuda, Jun, additional, Igarashi, Kazuhiko, additional, Shimizu, Ritsuko, additional, Nagasaki, Masao, additional, Koshiba, Seizo, additional, Kinoshita, Kengo, additional, Ogishima, Soichi, additional, Takai-Igarashi, Takako, additional, Tominaga, Teiji, additional, Tanabe, Osamu, additional, Ohuchi, Noriaki, additional, Shimosegawa, Toru, additional, Kure, Shigeo, additional, Tanaka, Hiroshi, additional, Ito, Sadayoshi, additional, Hitomi, Jiro, additional, Tanno, Kozo, additional, Nakamura, Motoyuki, additional, Ogasawara, Kuniaki, additional, Kobayashi, Seiichiro, additional, Sakata, Kiyomi, additional, Satoh, Mamoru, additional, Shimizu, Atsushi, additional, Sasaki, Makoto, additional, Endo, Ryujin, additional, Sobue, Kenji, additional, Tohoku Medical Megabank Project Study Group, the, additional, and Yamamoto, Masayuki, additional

Published
2016
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