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Monzen H, Tamura M, Kijima K, Otsuka M, Matsumoto K, Wakabayashi K, Choi MG, Yoon DK, Doi H, Akiyama H, Nishimura Y. Estimation of radiation shielding ability in electron therapy and brachytherapy with real time variable shape tungsten rubber. Phys Med 2019; 66:29-35. [PMID: 31550531 DOI: 10.1016/j.ejmp.2019.09.233] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 08/28/2019] [Accepted: 09/14/2019] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To clarify the physical characteristics of a newly developed real time variable shape rubber containing tungsten (STR) with changes in heat and estimate its shielding abilities against electron beams and γ-rays from 192Ir. METHODS Dynamic mechanical analysis for the STR (density = 7.3 g/cm3) was conducted at a frequency of 1.0 Hz in the temperature range of -60 °C to 60 °C. We evaluated tanδ, defined as the ratio (E″/E') between the storage modulus (E') and loss modulus (E″). The transmission rates were measured against 6- and 12-MeV electron beams and the percentage depth dose and lateral dose profile were compared with low-melting alloy (LMA). For the shielding rate of 192Ir against γ-rays, measurement data and Monte Carlo simulation data were obtained with STR thickness ranging from 1.0 mm to 16.0 mm. RESULTS At 36 °C, the tanδ value was 0.520, while at 60 °C, this value was 1.016. For 6- and 12-MeV electron beams, the transmission rates decreased with increasing STR thickness and reached plateaus at approximately 1.0% and 4.0% with STR thickness of >7.0 and >12.0 mm, respectively. The dose distributions were almost equal to those for LMA. Against γ-rays, the thickness of STR that obtained a 50% attenuation rate for 192Ir was 5.804 mm. The Monte Carlo calculation results were 2.6% higher on average than the measurement results. CONCLUSION The STR can be changed shape in real time at 60 °C and maintains its shape at body temperatures. It has adequate shielding abilities against megavoltage electron beams and γ-rays from 192Ir.
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Affiliation(s)
- Hajime Monzen
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama, Osaka 589-8511, Japan.
| | - Mikoto Tamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama, Osaka 589-8511, Japan
| | - Kenta Kijima
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama, Osaka 589-8511, Japan
| | - Masakazu Otsuka
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama, Osaka 589-8511, Japan; Department of Central Radiology, Kindai University Hospital, Osaka-Sayama, Osaka 589-8511, Japan
| | - Kenji Matsumoto
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama, Osaka 589-8511, Japan; Department of Central Radiology, Kindai University Hospital, Osaka-Sayama, Osaka 589-8511, Japan
| | - Kazuki Wakabayashi
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama, Osaka 589-8511, Japan
| | - Min-Geon Choi
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, Osaka-Sayama, Osaka 589-8511, Japan; Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 06591, South Korea
| | - Do-Kun Yoon
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 06591, South Korea
| | - Hiroshi Doi
- Department of Radiation Oncology, Faculty of Medicine, Kindai University, 377-2 Ohno-higashi, Osaka-Sayama, Osaka 589-8511, Japan
| | - Hironori Akiyama
- Department of Oral Radiology, Osaka Dental University, 1-5-17 Otemae Chuo-ku, Osaka 540-0008, Japan
| | - Yasumasa Nishimura
- Department of Radiation Oncology, Faculty of Medicine, Kindai University, 377-2 Ohno-higashi, Osaka-Sayama, Osaka 589-8511, Japan
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