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論文

Exposure inhomogeneity from $$^{241}$$Am and $$^{90}$$Sr/$$^{90}$$Y sources in terms of the eye lens monitoring in the nuclear facilities

吉富 寛; 古渡 意彦

Radiation Protection Dosimetry, 188(2), p.191 - 198, 2020/02

 被引用回数:0 パーセンタイル:100(Environmental Sciences)

This paper highlights the issues of exposure inhomogeneity that are relative to eye lens monitoring for low-energy photons from $$^{241}$$Am and beta-rays from $$^{90}$$Sr/$$^{90}$$Y including a personal protective equipment because eye lens exposure has been concerned more than before due to the proposed reduction of relevant dose limit. These nuclides are common sources in the nuclear industry, which are particularly of concern. Our previous study presented a quantitative estimation of exposure inhomogeneity, which was applied to simple but typical exposure situations to the radionuclides. For the present study, exposure inhomogeneity of $$^{241}$$Am was approximately within a factor of 1.6, implying a rather homogeneous situation than expected. Regarding $$^{90}$$Sr/$$^{90}$$Y exposure, estimation from both $$H_{rm p}$$(10) and $$H_{rm p}$$(0.07) on trunk would lead to an over- or underestimation by a factor of more than ten. In contrast, $$H_{rm p}$$(3) measurement on trunk will improve by up to a factor of two. With respect to the personal protective equipment, lead apron and protective glasses are effective for the 60-keV photons for both anterior-posterior (AP) and rotational (ROT) irradiations, while a full-face respirator can reduce the eye lens dose by approximately 17% for $$^{90}$$Sr/$$^{90}$$Y betas. As a whole, this study demonstrated that the effect of protective equipment can be effectively incorporated into the homogeneity evaluation.

論文

Quantitative estimation of exposure inhomogeneity in terms of eye lens and extremity monitoring for radiation workers in the nuclear industry

吉富 寛; 古渡 意彦; 萩原 雅之*; 長畔 誠司*; 中村 一*

Radiation Protection Dosimetry, 184(2), p.179 - 188, 2019/08

 被引用回数:1 パーセンタイル:58.8(Environmental Sciences)

To manage the equivalent doses for radiation workers, exposure inhomogeneity is an important factor in the decision-making process related to protection measures and additional monitoring. Our previous study proposed the methodology to evaluate the inhomogeneity of exposure quantitatively. In this study, we applied proposed method to five different types of actual exposure situations in the nuclear industry. Two of them were conventionally characterized as homogeneous exposure, but the other three as inhomogeneous exposure. The evaluation of homogeneity exposure was conducted using Monte Carlo calculations with two simplified models, which were then verified with phantom experiments. Consequently, all of the evaluations reproduced the experimental results, implying that our proposed method would be applicable for actual work conditions in the nuclear industry. Furthermore, the two presumed homogeneous exposure situations were found to be rather inhomogeneous because of the contribution of positrons and the limited source region. The investigation also implies that obtaining the information on the most probable posture of the exposed worker, as well as the existence of the weekly penetrating radiation such as $${beta}^{pm}$$ ray as a main source of exposure would be the key for more precise estimation.

論文

Composite-type optical fiberscope for laser surgery for twin-to-twin transfusion syndrome

岡 潔; 長縄 明大*; 山下 紘正*; 中村 哲也*; 千葉 敏雄*

Lecture Notes in Computer Science 5128, p.251 - 259, 2008/00

双胎間輸血症候群や胎児脊髄髄膜瘤等の先天性疾患の場合、出生後の治療には限界があり、一部の症例では胎児への治療、特に胎児内視鏡による外科治療が求められていたが、この治療が狭い空間である子宮内(羊水中)に浮遊する胎児を対象とすることから、現在の内視鏡手術機器には高度な技術的進歩が必要とされてきた。そこで本研究では、レーザー照射機能と観察機能を一体化した複合型光ファイバ技術(原子力機構が所有する特許)を医療機器に活用し、目視観察機能と患部を焼灼するためのレーザー照射機能を小型一体化した、「レーザー照射機能を有する極細径内視鏡」の開発を行った。本装置は外径2.2mmのレーザー照射機能と観察機能が一体化した内視鏡システムであり、本システムを使用して基本性能試験を行った結果、通常の光ファイバを使用したレーザー焼灼と比較し、複合型光ファイバスコープはレーザー出力の変動によらず、焼灼痕の大きさと深さが常に一定であり、安定した焼灼が可能であることが示された。

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