Development of wearable dosimeter for measuring X-ray doses in diagnostic region

2017 Fiscal Year Annual Research Report

• Project/Area Number: 15K19205
• Research Institution: The University of Tokushima
• Principal Investigator: 林 裕晃 徳島大学, 大学院医歯薬学研究部(医学系), 助教 (30422794)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: OSL線量計 / エネルギー依存性 / 実臨床データ / 被ばく線量 / 医療被曝 / 小児撮影

Outline of Annual Research Achievements

今年度は，OSL線量計の基礎特性の評価と臨床における患者や介助者の被ばく線量測定を行った．
まず，基礎評価については，医療で使用される連続X線を用いたときと，単色X線を用いたときにOSL線量計の検出効率の違いに与える影響をシミュレーションおよび実測で評価した．その結果，診断領域の連続X線は，単色X線で線量校正した値を用いて，被ばく線量測定が可能であることが初めて明らかになった．この結果は，OSL線量計を用いて実際の医療現場での被ばく線量測定を行う際に，重要なエビデンスになる．つまり，医療現場でOSL線量計を着用して被ばく線量測定を行う際には，エネルギーが既知な直接X線だけでなく，エネルギーが未知な散乱X線が混入することに注意する必要があるが，この結果により，エネルギーが未知のX線場に線量計を持ち込んだ際にも，正しい線量を算出できることを意味している．この検討をさらに発展させることで，X線透視下での術者の水晶体線量を測定する際に，術者が着用するX線シールド(防護眼鏡)などでX線が減弱し，その実効エネルギーが変化したとしても，メーカーや研究者が個別に決めた線量の校正値を使用することができることも分かった．
次に，OSL線量計を臨床現場に持ち込み，被爆線量測定を行った．具体的には，小児一般撮影における介助者への被ばく線量測定と小児CT検査における患者の線量測定を行った．小児一般撮影における線量測定では，介助者の受ける体幹部の線量は無視できるほど小さいという結果が得られたが，一方で患者を抑える手(手の甲)の被ばく線量は体患部に比べて大きいことが示された．またCT検査における被ばく線量測定では，初めての実臨床データが得られたことに意味がある．これらの測定技術を確立できたことは，今後，X線防護のための遮蔽体などの開発に生かすことができる．

Research Products

• [Journal Article] Direct Dose Measurement of Patients during Pediatric Computed Tomography Examination (2018)
  • Author(s): Hiroaki Hayashi, Emi Tomita, Sota Goto, Natsumi Kimoto, Keiji Tada, Ryosuke Kasai, Yuki Kanazawa, Yoshiki Mihara, Takashi Asahara, Tohru Okazaki, Takuya Hashizume and Vergil LE Cruz
  • Journal Title: Progress on Nuclear Science and Technology Volume: - Pages: -
  • Peer Reviewed
• [Journal Article] Energy and Angular Dependence of the Small-Type OSL Dosimeter in Nuclear Medicine Regions using Monte Carlo Simulation (2018)
  • Author(s): Vergil Lorenzo E. Cruz, Tohru Okazaki, Hiroaki Hayashi, Yoshiki Mihara, Takashi Asahara, Natsumi Kimoto, Hiroki Okino, Yuki Kanazawa, Takuya Hashizume, Ikuo Kobayashi
  • Journal Title: Progress on Nuclear Science and Technology Volume: - Pages: -
  • Peer Reviewed
• [Journal Article] Entrance surface dose measurements using a small OSL dosimeter with a computed tomography scanner having 320 rows of detectors (2017)
  • Author(s): Kazuki Takegami, Hiroaki Hayashi, Kenji Yamada, Yoshiki Mihara, Natsumi Kimoto, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Fumio Hayashi, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi
  • Journal Title: Radiological Physics and Technology Volume: 10 Pages: 49-59
  • DOI: 10.1007/s12194-016-0366-1
  • Peer Reviewed
• [Journal Article] Necessity of Direct Dose Measurement during Current X-ray Diagnosis, --- Our Approach Using a Small-type OSL Dosimeter --- (2017)
  • Author(s): Hiroaki Hayashi, Yoshiki Mihara, Yuki Kanazawa, Emi Tomita, Sota Goto, Kazuki Takegami, Tohru Okazaki, Takuya Hashizume and Vergil Estacio Lorenzo Cruz
  • Journal Title: Medical Research Archives Volume: 5 Pages: 1-20
  • Peer Reviewed / Open Access
• [Presentation] Preliminary study for eye lens dose evaluation of the medical staff during interventional fluoroscopy using Optically Stimulated Luminescence dosimeters (2018)
  • Author(s): Tohru Okazaki, Hiroaki Hayashi, Takashi Asahara, Sota Goto, Yoshiki Mihara, Emi Tomita, Yuki Kanazawa, Natsumi Kimoto, Takuya Hashizume, Vergil L E Cruz, Cheng Wei Hsin, Sumi Yokoyama, Ikuo Kobayashi
  • Organizer: 51st Annual meeting of Taiwan Society of Radiation Technology
  • Int'l Joint Research
• [Presentation] Phantom study using an OSL dosimeter with the aim of accurate measurement of eye lens dose exposure of operator during transfemoral cardiac catheterization using fluoroscopic examination (2018)
  • Author(s): Takashi Asahara, Hiroaki Hayashi, Emi Tomita, Sota Goto, Natsumi Kimoto, Kenji Yamada, Sumi Yokoyama, Yuki Kanazawa, Tohru Okazaki
  • Organizer: uropean Congress of Radiology
  • Int'l Joint Research
• [Presentation] Universal calibration curve for a small-type OSL dosimeter to be used for direct dose measurements of direct, scattered and penetrating X-rays in the diagnostic region (2017)
  • Author(s): Kazuki Takegami, Hiroaki Hayashi, Natumi Kimoto, Yoshiki Mihara, Yuki Kanazawa, Kousaku Higashino, Kazuta Yamashita, Fumio Hayashi, Tohru Okazaki, Takuya Hashizume and Ikuo Kobayashi
  • Organizer: Radiological Society of North America (RSNA)
  • Int'l Joint Research / Invited
• [Presentation] Energy dependence of nanoDot OSL dosimeters to low energy X-rays using Monte-Carlo simulation code EGS5 (2017)
  • Author(s): Cruz LE Vergil, GOTO Sota, OKAZAKI Tohru, Hiroaki Hayashi, TOMITA Emi, MIHARA Yoshiki, ASAHARA Takashi, HASHIZUME Takuya, Cheng Wei Hsin and KOBAYASHI Ikuo
  • Organizer: AOCMP-AMPICON 2017
  • Int'l Joint Research
• [Presentation] Practical phantom study using small-type OSL dosimeter toward direct dose measurement during pediatric CT examination (2017)
  • Author(s): OKAZAKI Tohru, Hiroaki Hayashi, TOMITA Emi, GOTO Sota, TADA Keiji, MIHARA Yoshiki, KIMOTO Natsumi, KASAI Ryosuke, Yuki Kanazawa, CRUZ LE Vergil, HASHIZUME Takuya, Hsin Wei Cheng and KOBAYASHI Ikuo
  • Organizer: AOCMP-AMPICON 2017
  • Int'l Joint Research
• [Presentation] Evaluating the Influence of the Small-type Optically Stimulated Luminescence (OSL) Dosimeter on CT Images for Radiation Dose Measurement of Patient (2017)
  • Author(s): Hsin Wei Cheng, OKAZAKI Tohru, HASHIZUME Takuya, Hiroaki Hayashi, TOMITA Emi, TADA Keiji and Yuki Kanazawa
  • Organizer: The 3rd International Conference on Radiological Science and Technology
  • Int'l Joint Research
• [Presentation] Precise calibration factor of small-type OSL dosimeter with the aim toward analysis of exposure doses caused by scattering X-ray in the diagnostic region (2017)
  • Author(s): MIHARA Yoshiki, Hiroaki Hayashi, ASAHARA Takashi, GOTO Sota, KIMOTO Natsumi, Yuki Kanazawa and OKAZAKI Tohru
  • Organizer: The 3rd International Conference on Radiological Science and Technology
  • Int'l Joint Research
• [Presentation] Energy and Angular Dependence of the small type OSL Dosimeter in Diagnostic and Nuclear Medicine Regions using Monte Carlo Simulation (2017)
  • Author(s): Cruz Lorenzo E. Vergil, OKAZAKI Tohru, Hiroaki Hayashi, MIHARA Yoshiki, ASAHARA Takashi, KIMOTO Natsumi, OKINO Hiroki, Yuki Kanazawa, HASHIZUME Takuya and KOBAYASHI Ikuo
  • Organizer: International Symposium On Radiation Safety and Detection Technology (ISORD-9)
  • Int'l Joint Research
• [Presentation] Applicability of Practical Calibration of a Small-type OSL Dosimeter For Measuring the Exposure Doses Effected by Scattered and Penetrating X-rays (2017)
  • Author(s): OKAZAKI Tohru, Hiroaki Hayashi, MIHARA Yoshiki, ASAHARA Takashi, KIMOTO Natsumi, Yuki Kanazawa, Kousaku Higashino, YAMASHITA Kazuta, YOKOYAMA Sumi, TAKEGAMI Kazuki, HASHIZUME Takuya and CRUZ LE Vergil
  • Organizer: International Symposium On Radiation Safety and Detection Technology (ISORD-9)
  • Int'l Joint Research
• [Presentation] Direct Dose Measurement of Patients during Pediatric Computed Tomography Examination (2017)
  • Author(s): Hiroaki Hayashi, TOMITA Emi, GOTO Sota, KIMOTO Natsumi, TADA Keiji, KASAI Ryosuke, Yuki Kanazawa, MIHARA Yoshiki, ASAHARA Takashi, OKAZAKI Tohru, HASHIZUME Takuya and CRUZ LE Vergil
  • Organizer: International Symposium On Radiation Safety and Detection Technology (ISORD-9)
  • Int'l Joint Research
• [Presentation] 小児CT撮影における被ばく線量の実測と装置表示値との比較 (2017)
  • Author(s): 景山 紗貴，多田 佳司，岡 春奈，安田 謙二，林 裕晃，三原 由樹，冨田 恵美，後藤聡汰，岡崎 徹
  • Organizer: 第13回中四国放射線医療技術フォーラム
• [Presentation] 320-row volumetric scanにおける小児CT検査の被ばく線量解析に向けた基礎検討 (2017)
  • Author(s): 多田佳司, 岡春奈, 景山紗貴, 林 裕晃, 三原由樹, 岡崎徹, 市川勝弘, 冨田恵美, 後藤聡汰, 安田謙二
  • Organizer: 第45回日本放射線技術学会秋季学術大会
• [Presentation] 小型OSL線量計を用いた新生児胸部CT検査における散乱X線による水晶体および生殖腺の被ばくの実測 (2017)
  • Author(s): 岡春奈, 多田佳司, 景山紗貴, 安田謙二, 林 裕晃, 岡崎徹, 冨田恵美, 後藤聡汰
  • Organizer: 第45回日本放射線技術学会秋季学術大会
• [Presentation] 小型OSL線量計を用いた超精密測定に向けた固有効率の決定 (2017)
  • Author(s): 後藤 聡汰, 林 裕晃, 三原 由樹, 淺原 孝, 冨田 恵美, 金澤 裕樹, 岡崎 徹, 橋詰 拓弥, Vergil LE Cruz
  • Organizer: 第45回日本放射線技術学会秋季学術大会
• [Presentation] Visualization of entrance surface dose during CT examination using small-type OSL dosimeter (2017)
  • Author(s): Mihara Yoshiki, Hiroaki Hayashi, Yuki Kanazawa, Yamada Kenji, Takegami Kazuki, Okazaki Tohru and Hashizume Takuya
  • Organizer: 第73回日本放射線技術学会総会学術大会
• [Remarks] 研究グループのHP：金沢大学歯薬保健研究域保健学系
  • URL: http://hayashi.w3.kanazawa-u.ac.jp/