Vol.5 No.4 2013

Research paper : Dose standards for safe and secure breast cancer screening (T. Tanaka et al.)−238−Synthesiology - English edition Vol.5 No.4 (2013) AuthorsTakahiro TanakaCompleted the course in Physics at the Graduate School of Science and Technology, Sophia University in 2008. Doctor (Science). Joined AIST in 2008. Researcher at the Ionizing Radiation Section, Quantum Radiation Division, National Metrology Institute of Japan, AIST. Engages in research for the dose standard of soft X-ray and mammography X-ray. In this paper, was mainly in charge of the R&D and calibration service for the overall mammography dose standard, international key comparison, and drafting of the paper.Tadahiro KurosawaCompleted the course at the Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University in 2000. Doctor (Engineering). Joined the Electrotechnical Laboratory, Agency of Industrial Science and Technology (currently AIST) in 2000. Worked on the -ray standard as a visiting researcher at the Physikalisch-Technische Bundesanstalt (PTB), Germany for three months in 2003. Senior researcher at the Ionizing Radiation Section, Quantum Radiation Division, National Metrology Institute of Japan, AIST. Engages in the development of -ray and X-ray standards. In this paper, was in charge of the Monte Carlo calculation and the international comparison of the mammography dose standard.Norio SaitoCompleted the course in Electric Engineering at the Graduate School of Science and Engineering, Waseda University in 1984. Joined the Electrotechnical Laboratory, Agency of Industrial Science and Technology (currently AIST) in 1984. Doctor (Science). Senior researcher in 1991; senior research at the Ionizing Radiation Section, Quantum Radiation Division, National Metrology Institute of Japan, AIST in 2001; section chief in 2005; and division head in 2011. Researcher at the Fritz-Haber-Institut, Germany in 1993~1994. Engages in research of dosimetry standards and radiometry. In this paper, was in charge of planning and organizing the overall concept of mammography dose standard.Discussions with Reviewers1 Overall evaluationComment (Naoto Kobayashi, Center for Research Strategy, Waseda University)I think this paper is highly significant from the perspective of “establishing the dose standard and traceability for mammography X-rays.” Particularly, the major result is that you have achieved this in a short time of about one and half years, from the start of development to the start of dissemination.Comment (Akira Ono, AIST)This paper describes an excellent research result where you set up a solid scenario covering the whole from the establishment of the primary standard for X-ray dose to the development of the standard dissemination system. You realized both the reliability and safety of mammography, and achieved it in a short time. I think there are many points that will be useful to the readers. Also, the firm frame and development of logic as seen in the individual chapters enhance the reliability of the contents and allow easy understanding by the readers.2 Utilization of existing resourcesComment (Akira Ono)In Chapter 1 Introduction you state that the development and dissemination of standards were achieved in a short period of about one and half years “by fully utilizing the existing research facilities and technologies.” Also you state that you worked “to construct quick and wide dissemination by incorporating the standards into the current mammography quality control system that existed in private sectors.” I think your efforts in utilizing the existing resources and current systems were the keys in conducting the R&D at a faster pace than usual.If there are any points that the authors paid attention in utilizing the existing resources and incorporating the standards into current quality control system, please mention them, as they will be useful to other researchers. They may be lessons learned by the authors from this experience.Answer (Takahiro Tanaka)The points to keep in mind when utilizing the existing resources were to note their potential as well as their limitations. For example, the ability to conclude whether the free air ionization chamber, which was the resource used in this research, was capable of sufficient performance as a national standard for mammography radiation quality or not, was required of the researchers. I think the ability to see this affects the success or failure of Full Research.Additionally, when developing a standard dissemination service, I think it is important to comprehensively understand the process of dose evaluation in the industry and in the academic societies. I think that AIST, the industry, and academic societies had a strong desire to incorporate traceability, the final objective, into the current control system.3 Technological issues that were overcomeQuestion (Naoto Kobayashi)I ask about the technological issues in achieving the objective of this research. The mammography X-rays are characterized by the low energy of about 30 keV. I think the technical point is to use the method of determining the correction factors for the current free air ionization chamber to establish the dose standard. What were the difficult issues that you had to overcome?Also, there are large differences in the calibration coefficients of the ionization chambers A, B, and C (see Fig. 3). What are the reasons for these differences?Answer (Takahiro Tanaka)Although there were several technological issues in the standards of the NMIJ and the BIPM in low-energy x-rays, Metrologia, 45, 06015 (2008).[17]BIPM Key Comparison Database [database online]. http://kcdb.bipm.org/


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