Dose Estimation Model for Terminal Buds in Radioactively Contaminated Fir Trees

Kawaguchi, Isao,Kido, Hiroko,Watanabe, Yoshito The Korean Association for Radiation Protection 2022 방사선방어학회지 Vol.47 No.3

Background: After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, biological alterations in the natural biota, including morphological changes of fir trees in forests surrounding the power plant, have been reported. Focusing on the terminal buds involved in the morphological formation of fir trees, this study developed a method for estimating the absorbed radiation dose rate using radionuclide distribution measurements from tree organs. Materials and Methods: A phantom composed of three-dimensional (3D) tree organs was constructed for the three upper whorls of the fir tree. A terminal bud was evaluated using Monte Carlo simulations for the absorbed dose rate of radionuclides in the tree organs of the whorls. Evaluation of the absorbed dose targeted ¹³¹I, ¹³⁴Cs, and ¹³⁷Cs, the main radionuclides subsequent to the FDNPP accident. The dose contribution from each tree organ was calculated separately using dose coefficients (DC), which express the ratio between the average activity concentration of a radionuclide in each tree organ and the dose rate at the terminal bud. Results and Discussion: The dose estimation indicated that the radionuclides in the terminal bud and bud scale contributed to the absorbed dose rate mainly by beta rays, whereas those in 1-year-old trunk/branches and leaves were contributed by gamma rays. However, the dose contribution from radionuclides in the lower trunk/branches and leaves was negligible. Conclusion: The fir tree model provides organ-specific DC values, which are satisfactory for the practical calculation of the absorbed dose rate of radiation from inside the tree. These calculations are based on the measurement of radionuclide concentrations in tree organs on the 1-year-old leader shoots of fir trees. With the addition of direct gamma ray measurements of the absorbed dose rate from the tree environment, the total absorbed dose rate was estimated in the terminal bud of fir trees in contaminated forests.

Posttreatment cut-off levels of squamous cell carcinoma antigen as a prognostic factor in patients with locally advanced cervical cancer treated with radiotherapy

Ryuji Kawaguchi,Naoto Furukawa,Hiroshi Kobayashi,Isao Asakawa 대한부인종양학회 2013 Journal of Gynecologic Oncology Vol.24 No.4

Objective: The aim of the present study was to assess prognostic factors for patients with locally advanced cervical cancer treated with radiotherapy as the primary treatment and to assess the posttreatment cut-off levels of squamous cell carcinoma antigen (SCC-Ag) to predict three-year overall survival (OS) rates. Methods: One hundred and twenty-eight patients with cervical squamous cell carcinoma (International Federation of Gynecology and Obstetrics [FIGO] stage IIB-IVA) treated using radiotherapy or concurrent chemoradiotherapy were identified. Of these patients, 116 who had SCC-Ag levels >1.5 ng/mL prior to treatment were analyzed retrospectively. Results: Median age was 68 years (range, 27 to 79 years). The complete response rate was 70.7% and the three-year OS rate was 61.1%. The median levels of pretreatment and posttreatment SCC-Ag were 11.5 ng/mL (range, 1.6 to 310.0 ng/mL) and 0.9 ng/mL (range, 0.4 to 41.0 ng/mL), respectively. Multivariate analysis showed that pretreatment anemia (p=0.041), pelvic lymph node metastasis (p=0.016) and posttreatment SCC-Ag levels (p=0.001) were independent prognostic factors for three-year OS. The SCC-Ag level cut-off point for three-year OS rates, calculated using a receiver operating characteristic curve, was 1.15 ng/mL (sensitivity, 80.0%; specificity, 74.0%). Conclusion: Pretreatment anemia and pelvic lymph node metastasis are poor prognostic factors in locally advanced cervical cancer. Furthermore, posttreatment SCC-Ag levels <1.15 ng/mL predicted better three-year OS rates.

Conclusions and Suggestions on Low-Dose and Low-Dose Rate Radiation Risk Estimation Methodology

Sakai, Kazuo,Yamada, Yutaka,Yoshida, Kazuo,Yoshinaga, Shinji,Sato, Kaoru,Ogata, Hiromitsu,Iwasaki, Toshiyasu,Kudo, Shin'ichi,Asada, Yasuki,Kawaguchi, Isao,Haeno, Hiroshi,Sasaki, Michiya The Korean Association for Radiation Protection 2021 방사선방어학회지 Vol.46 No.1

Background: For radiological protection and control, the International Commission on Radiological Protection (ICRP) provides the nominal risk coefficients related to radiation exposure, which can be extrapolated using the excess relative risk and excess absolute risk obtained from the Life Span Study of atomic bomb survivors in Hiroshima and Nagasaki with the dose and dose-rate effectiveness factor (DDREF). Materials and Methods: Since it is impossible to directly estimate the radiation risk at doses less than approximately 100 mSv only from epidemiological knowledge and data, support from radiation biology is absolutely imperative, and thus, several national and international bodies have advocated the importance of bridging knowledge between biology and epidemiology. Because of the accident at the Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi Nuclear Power Station in 2011, the exposure of the public to radiation has become a major concern and it was considered that the estimation of radiation risk should be more realistic to cope with the prevailing radiation exposure situation. Results and Discussion: To discuss the issues from wide aspects related to radiological protection, and to realize bridging knowledge between biology and epidemiology, we have established a research group to develop low-dose and low-dose-rate radiation risk estimation methodology, with the permission of the Japan Health Physics Society. Conclusion: The aim of the research group was to clarify the current situation and issues related to the risk estimation of low-dose and low-dose-rate radiation exposure from the viewpoints of different research fields, such as epidemiology, biology, modeling, and dosimetry, to identify a future strategy and roadmap to elucidate a more realistic estimation of risk against low-dose and low-dose-rate radiation exposure.

Tofacitinib induction and maintenance therapy in East Asian patients with active ulcerative colitis: subgroup analyses from three phase 3 multinational studies

( Satoshi Motoya ),( Mamoru Watanabe ),( Hyo Jong Kim ),( Young Ho Kim ),( Dong Soo Han ),( Hirotoshi Yuasa ),( Junichi Tabira ),( Naoki Isogawa ),( Shoko Arai ),( Isao Kawaguchi ),( Toshifumi Hibi ) 대한장연구학회 2018 Intestinal Research Vol.16 No.2

Background/Aims: Tofacitinib is an oral, small-molecule Janus kinase inhibitor being investigated for ulcerative colitis (UC). In OCTAVE Induction 1 and 2, patients with moderately to severely active UC received placebo or tofacitinib 10 mg twice daily (BID) for 8 weeks. Clinical responders in OCTAVE Induction were re-randomized to 52 weeks’ therapy with placebo, tofacitinib 5 mg BID, or tofacitinib 10 mg BID. Methods: We conducted post-hoc efficacy and safety analyses of East Asian patients in OCTAVE Induction 1 and 2 and OCTAVE Sustain. Results: A total of 121 East Asian (Japan, Korea, and Taiwan) patients were randomized in OCTAVE Induction 1 and 2 (placebo, n=26; tofacitinib 10 mg BID, n=95), and 63 in OCTAVE Sustain (placebo, n=20; tofacitinib 5 mg BID, n=22; tofacitinib 10 mg BID, n=21). At week 8 of OCTAVE Induction 1 and 2, 18.9% of patients (18/95) achieved remission with tofacitinib 10 mg BID versus 3.8% (1/26) with placebo. In OCTAVE Sustain, the week 52 remission rates were 45.5% (10/22), 47.6% (10/21), and 15.0% (3/20) with 5 mg BID, 10 mg BID, and placebo, respectively. Adverse event rates were similar between groups in OCTAVE Induction and numerically higher with tofacitinib in OCTAVE Sustain. Serious adverse event rates were similar across groups in all studies. Infections were numerically more frequent with tofacitinib than placebo. Increases in serum lipid levels were observed with tofacitinib. Conclusions: In East Asian patients with UC, tofacitinib demonstrated numerically greater efficacy versus placebo as induction and maintenance therapy, with a safety profile consistent with the global study population. ClinicalTrials.gov: NCT01465763; NCT01458951; NCT01458574. (Intest Res 2018;16:233-245)

Corrigendum: Tofacitinib induction and maintenance therapy in East Asian patients with active ulcerative colitis: subgroup analyses from three phase 3 multinational studies

( Satoshi Motoya ),( Mamoru Watanabe ),( Hyo Jong Kim ),( Young Ho Kim ),( Dong Soo Han ),( Hirotoshi Yuasa ),( Junichi Tabira ),( Naoki Isogawa ),( Shoko Arai ),( Isao Kawaguchi ),( Toshifumi Hibi ) 대한장연구학회 2018 Intestinal Research Vol.16 No.3