著者

松本 義久

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.34, no.2, pp.57-64, 2014 (Released:2015-03-06)

参考文献数

15

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DNA double-strand break (DSB) is considered most deleterious among radiation-induced DNA damages and most relevant to the biological effects of radiation. In eukaryotic cells, DSB is repaired mainly through two pathways: non-homologous end-joining (NHEJ) and homologous recombination (HR). These repair pathways seem to play complementary roles. NHEJ is considered less accurate than HR, but HR is available only in late S and G2 phases in vertebrates. Recent studies elucidated how cells choose one from these two pathways depending on the circumstance: cell cycle phase, complexity of DNA damage and chromatin structure.

著者

河野 俊之

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.35, no.2, pp.173-179, 2015 (Released:2016-07-01)

著者

土井 邦雄

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.42, no.1, pp.55-62, 2022-03-31 (Released:2022-03-31)

著者

土井 邦雄

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.41, no.1, pp.48-50, 2021

著者

有村 秀孝

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.39, no.1, pp.2-6, 2019-05-31 (Released:2019-06-05)

参考文献数

22

著者

岡本 裕之 太田 誠一 川守田 龍 坂本 昌隆 中村 哲志 西岡 史絵 株木 重人 正井 範尚 水野 統文 古谷 智久 山本 鋭二郎 飯島 康太郎 伊藤 芳紀 勝田 昭一 黒岡 将彦 川村 愼二 橘 英伸 遠山 尚紀 中村 勝 峯村 俊行 中山 優子

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.40, no.1, pp.28-34, 2020-03-31 (Released:2020-03-31)

参考文献数

2

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In 2016, the American Association of Physicists in Medicine (AAPM) has published a report of task group (TG) 100 with a completely new concept, entitled “application of risk analysis methods to radiation therapy quality management.” TG-100 proposed implementation of risk analysis in radiotherapy to prevent harmful radiotherapy accidents. In addition, it enables us to conduct efficient and effective quality management in not only advanced radiotherapy such as intensity-modulated radiotherapy and image-guided radiotherapy but also new technology in radiotherapy. It should be noted that treatment process in modern radiotherapy is absolutely more complex and it needs skillful staff and adequate resources. TG-100 methodology could identify weakness in radiotherapy procedure through assessment of failure modes that could occur in overall treatment processes. All staff in radiotherapy have to explore quality management in radiotherapy safety.

著者

松原 孝祐

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.36, no.1, pp.62-66, 2016-05-31 (Released:2016-11-30)

参考文献数

28

著者

平山 亮一

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.34, no.2, pp.65-69, 2014 (Released:2015-03-06)

参考文献数

26

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The oxygen effect was observed as 1912 by Swartz. The ratio of doses administered under hypoxic to oxic conditions needed to achieve the same biological effect is called the oxygen enhancement ratio (OER). For low-LET radiation, such as photon radiation, the OER at high doses has a value of between 2.5 and 3, and the OER has a smaller value of about 2.5 or less at lower doses. The oxygen effect is large and important in the case of low-LET radiations. Radio-chemical reactions are generally believed to be the fundamental mechanisms underlying oxygen effects. Oxygen fixes the damage produced by free radical. In the absence of oxygen, damage produced by the indirect action may be repaired. The OER has been determined for a wide variety of chemical and biologic systems with different endpoints. For high-LET radiation such as heavy-ions, oxygen effect is very small. The oxygen-in-the-track hypothesis proposed to account for this effect, suggests that cells exposed to high-LET radiation exhibit an oxygenated microenvironment around the particle track, even when they are irradiated under anoxic conditions.

著者

只野 喜一 磯辺 智範 佐藤 英介 武居 秀行 小林 大輔 森 祐太郎 富田 哲也 榮 武二

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.36, no.3, pp.148-150, 2016 (Released:2017-04-24)

参考文献数

4

被引用文献数

1

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Treatment planning systems with highly accurate dose calculation algorithms such as Monte-Carlo method and linear Boltzmann transport equation are becoming popular thanks to a development of the computer technology. These algorithms use new concepts, dose-to-medium and dose-to-water. However, introducing these concepts can cause confusion in clinical sites. Basic knowledges about Monte-Carlo simulation and other corresponding algorithms were explained in this article such as the principles, the parameters and words of caution.

著者

山田 幸子 上口 貴志 尾方 俊至 荻原 良太 村瀬 研也

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.34, no.2, pp.35-46, 2014 (Released:2015-03-06)

参考文献数

19

被引用文献数

1

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An iterative reconstruction (IR) technique in computed tomography (CT) is expected to play an important role in reducing the radiation dose while preserving both spatial resolution and contrast-to-noise ratio. However, images obtained by using the IR technique are known to have different visual appearances from those obtained by using the traditional filtered back-projection (FBP) reconstruction. This appearance is often figuratively described as “blocky,” but it has not been objectively characterized further. In this paper, we propose a novel image quality metric, called “perceptual image dissimilarity” (PID), to characterize the visual dissimilarity between FBP and IR images. The PID was formulated as a grayscale transformation and subsequent structural similarity (SSIM)-based image quality measurement. The PID metric was validated using phantom images with three different modules. Sixty datasets, each consisting of an IR image and its corresponding noise-level-equivalent FBP image, were visually assigned “subjective dissimilarity scores” on a five level scale by six observers. The data sets were then quantitatively analyzed using both the PID and the traditional mean squared error (MSE) metrics. Our results show that the PID is highly consistent with the subjective dissimilarity score and thus delivers superior performance, whereas the MSE fails to quantify the observers’ visual perception.

著者

村瀬 研也

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.35, no.4, pp.297-306, 2016 (Released:2016-08-31)

参考文献数

11

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In this issue, simultaneous differential equations were introduced. These differential equations are often used in the field of medical physics. The methods for solving them were also introduced, which include Laplace transform and matrix methods. Some examples were also introduced, in which Laplace transform and matrix methods were applied to solving simultaneous differential equations derived from a three-compartment kinetic model for analyzing the glucose metabolism in tissues and Bloch equations for describing the behavior of the macroscopic magnetization in magnetic resonance imaging.In the next (final) issue, partial differential equations and various methods for solving them will be introduced together with some examples in medical physics.

著者

村瀬 研也

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.34, no.4, pp.227-235, 2015 (Released:2015-12-16)

参考文献数

8

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Utilization of differential equations and methods for solving them in medical physics are presented. First, the basic concept and the kinds of differential equations were overviewed. Second, separable differential equations and well-known first-order and second-order differential equations were introduced, and the methods for solving them were described together with several examples.In the next issue, the symbolic and series expansion methods for solving differential equations will be mainly introduced.

著者

村瀬 研也

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.35, no.1, pp.49-58, 2015 (Released:2016-01-31)

参考文献数

11

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In this issue, symbolic methods for solving differential equations were firstly introduced. Of the symbolic methods, Laplace transform method was also introduced together with some examples, in which this method was applied to solving the differential equations derived from a two-compartment kinetic model and an equivalent circuit model for membrane potential. Second, series expansion methods for solving differential equations were introduced together with some examples, in which these methods were used to solve Bessel’s and Legendre’s differential equations.In the next issue, simultaneous differential equations and various methods for solving these differential equations will be introduced together with some examples in medical physics.

著者

仲本 宗泰 芳賀 昭弘 高橋 渉

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.38, no.3, pp.129-134, 2018-12-25 (Released:2018-12-25)

参考文献数

41

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Recently, in a medical field, quantitative data mining is a hot topic for performing a precision (or personalized) medicine. Although a molecular biological data has been mainly utilized for data mining in this field, medical images are also important minable data. Radiomics is a comprehensive analysis methodology for describing tumor phenotypes or molecular biological expressions (e.g. genotypes) using minable feature extracted from a large number of medical images. In this review paper, we introduce to a framework of the radiomics.

著者

錦戸 文彦 田島 英朗 吉田 英治 山谷 泰賀

出版者

公益社団法人 日本医学物理学会

雑誌

医学物理 (ISSN:13455354)

巻号頁・発行日

vol.38, no.1, pp.10-18, 2018-05-31 (Released:2018-08-17)

参考文献数

37

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Nuclear medicine imaging is an important tool for cancer diagnosis, brain research, molecular imaging research and so on. Therefore, various imaging techniques and methods are being developed and investigated in nuclear medicine physics. In this report, we introduce state-of-the-art techniques, such as Compton camera imaging, time-of-flight positron emission tomography, semiconductor detectors for medical applications, image reconstruction and deep learning, which were reported in the 2017 IEEE Nuclear Science Symposium & Medical Imaging Conference.