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A Four-Layer DOI Detector With a Relative Offset for Use in an Animal PET System
Mikiko Ito,Jae Sung Lee,Sun Il Kwon,Geon Song Lee,Byungsik Hong,Kyong Sei Lee,Kwang-Souk Sim,Seok Jae Lee,June Tak Rhee,Seong Jong Hong IEEE 2010 IEEE transactions on nuclear science Vol.57 No.3
<P>For animal PET systems to achieve high sensitivity without adversely affecting spatial resolution, they must have the ability to measure depth-of-interaction (DOI). In this paper, we propose a novel four-layer PET system, and present the performances of modules built to verify the concept of the system. Each layer in the four-layer PET system has a relative offset of half a crystal pitch from other layers. Performances of the four-layer detector were estimated using a GATE Monte Carlo simulation code. The proposed system consists of six H9500 PMTs, each of which contains 3193 crystals. A sensitivity of 11.8% was obtained at the FOV center position of the proposed system. To verify the concept, we tested a PET module constructed using a H9500 flat panel PMT and LYSO crystals of cross-sectional area 1.5 × 1.5 mm<SUP>2</SUP>. The PET module was irradiated with a 1.8 MBq <SUP>22</SUP>Na radiation source from the front or side of the crystals to obtain flood images of each crystal. Collimation for side irradiation was achieved using a pair of lead blocks of dimension 50 × 100 × 200 mm<SUP>3</SUP>. All crystals in the four layers were clearly identified in flood images, thus verifying the DOI capability of the proposed four-layer PET system. We also investigated the optimal combination of crystal lengths in the four-layer PET system using the GATE Monte Carlo simulation code to generate events from simulated radiation sources, and using the ML-EM algorithm to reconstruct simulated radiation sources. The combination of short crystal lengths near radiation sources and long crystal lengths near the PMT provides better spatial resolution than combinations of same crystal lengths in the four-layer PET system.</P>
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Mikiko Asai-Sato,Nao Suzuki,Hitomi Sakai,Yoshio Itani,Shinya Satoh,Masayuki Futagami,Yoshio Yoshida 대한부인종양학회 2023 Journal of Gynecologic Oncology Vol.34 No.1
Objective: This study aimed to assess gynecologic oncologists (GOs)’ perceptions and attitudes toward cancer survivorship to help improve survivor care. Methods: We conducted a web-based questionnaire survey about survivorship issues for the GOs belonging to the Japan Gynecologic Oncology Group. We analyzed the proactiveness of the participants toward addressing 25 survivor issues. In addition, the practice patterns and barriers to care for survivors’ long-term health issues, such as second primary cancer (SPC) and lifestyle-related diseases (LSRD), and return-to-work (RTW) support were assessed. Results: We received 313 responses. The respondents had a mean of 22 years of physician experience. The ratio of men to women was approximately 7:3, and 84.7% worked at facilities for multidisciplinary cancer treatment. The respondents’ proactiveness for addressing psychosocial problems was significantly lower than physical and gynecological issues (p<0.01 by χ2 test). However, most GOs tried to contribute to such issues according to patients’ demands. Women GOs were more proactively involved in some survivorship issues than the men (p<0.05 by logistic regression analysis). The rates of the respondents who proactively discussed SPC, LSRD, and RTW were unexpectedly high (60.7%, 36.1%, and 52.4%, respectively). However, the GOs only provided verbal support for these issues in many cases. Conclusion: The Japanese GOs were enthusiastic about survivorship care. However, their tendency to deal with survivors’ problems through their own knowledge and judgments raises concerns about the quality of care. Therefore, creating survivorship care guidelines and enhancing multidisciplinary collaboration should be prioritized.
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Mikiko Matsuda,Tomoko Hayashi,Kazumi Imura 한국간호과학회 2021 한국간호과학회 학술대회 Vol.2021 No.10
Aim(s): To clarify novice nurses (novices)’ and nursing supervisors (supervisors)’ views on the application of skills learned from off-the-job training (Off-JT), situations where supervisors provide support for novices as part of supervision in on-the-job training (OJT), and the details of such support as a basis for effective support for novices to apply the skills they have learned from Off-JT in actual settings. Method(s): The participants were 4 supervisors of a single facility and 3 novices who had been supervised by these supervisors in the same facility. Data were collected through semi-structured interviews. During the interviews, the participants were asked about the skills learned from Off-JT and applied/not applied in actual settings, as well as the supervisory approaches provided in OJT. Data analysis was performed, adopting a qualitative, descriptive method. The study was approved by the Research Ethics Committee of Mie University Graduate School/Faculty of Medicine. Result(s): The category [understanding of manual techniques and procedures] represents the skills learned from Off-JT considered by both the supervisors and novices as applicable in actual settings. In contrast, the category [management of patients according to their responses] represents those considered by both parties as difficult to apply in such settings. In OJT, 3 situations were identified: 〈observation〉, 〈monitoring〉, and 〈reflection〉. Supervisory approaches for 〈observation〉 were summarized into [manual techniques and procedures] etc. Those for 〈monitoring〉 were represented by [pointing out mistakes and giving instructions to novices] and [following up patients]. 〈Reflection〉 was recounted by [reflecting together] etc. Conclusion(s): The identified skills learned from Off-JT and applied/not applied in actual settings suggest that both supervisors and novices define ‘performing the manual techniques and procedures one has learned as they are in actual settings’ as the application of learned skills. On the other hand, they considered that changing and using one’s acquired knowledge according to patients’ responses are also involved.
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Positron Emission Tomography (PET) Detectors with Depth-of- Interaction (DOI) Capability
Mikiko Ito,홍성종,이재성 대한의용생체공학회 2011 Biomedical Engineering Letters (BMEL) Vol.1 No.2
Because positron emission tomography (PET) provides biochemical information in vivo with the sensitivity at the sub-pico-molar level, pre-clinical research using PET plays an important role in biological and pharmaceutical sciences. However, small animal imaging by PET has been challenging with respect to spatial resolution and sensitivity due to the small volume of the imaging objects. A DOI-encoding technique allows for pre-clinical PET to simultaneously achieve high spatial resolution and high sensitivity. Thus many DOI-encoding methods have been proposed. In this paper we describe why DOI measurements are important, what is required in DOI-encoding designs, and how to extract DOI information in scintillator-based DOI detectors. Recently, there has been a growing interest in DOI measurements for TOF PET detectors to correct time walk as a function of DOI position. Thus, the DOI-encoding method with a high time performance suitable for TOF detectors is now required. The requirements to improve the time resolution in DOI detectors are discussed as well.
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Ito, Mikiko,Lee, Jae Sung,Park, Min-Jae,Sim, Kwang-Souk,Hong, Seong Jong Institute of Physics in association with the Ameri 2010 Physics in medicine & biology Vol.55 No.13
<P>PET detectors with depth-of-interaction (DOI) encoding capability allow high spatial resolution and high sensitivity to be achieved simultaneously. To obtain DOI information from a mono-layer array of scintillation crystals using a single-ended readout, the authors devised a method based on light spreading within a crystal array and performed Monte Carlo simulations with individual scintillation photon tracking to prove the concept. A scintillation crystal array model was constructed using a grid method. Conventional grids are constructed using comb-shaped reflector strips with rectangular teeth to isolate scintillation crystals optically. However, the authors propose the use of triangularly shaped teeth, such that scintillation photons spread only in the <I>x</I>-direction in the upper halves of crystals and in the <I>y</I>-direction in lower halves. DOI positions can be estimated by considering the extent of two-dimensional light dispersion, which can be determined from the multiple anode outputs of a position-sensitive PMT placed under the crystal array. In the main simulation, a crystal block consisting of a 29 × 29 array of 1.5 mm × 1.5 mm × 20 mm crystals and a multi-anode PMT with 16 × 16 pixels were used. The effects of crystal size and non-uniform PMT output gain were also explored by simulation. The DOI resolution estimated for 1.5 × 1.5 × 20 mm<SUP>3</SUP> crystals was 2.16 mm on average. Although the flood map was depth dependent, each crystal was well identified at all depths when a corner of the crystal array was irradiated with 511 keV gamma rays (peak-to-valley ratio ∼9:1). DOI resolution was better than 3 mm up to a crystal length of 28 mm with a 1.5 × 1.5 mm<SUP>2</SUP> or 2.0 × 2.0 mm<SUP>2</SUP> crystal surface area. The devised light-sharing method allowed excellent DOI resolutions to be obtained without the use of dual-ended readout or multiple crystal arrays.</P>
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김중현,Mikiko Ito,김수미,홍성종,이재성 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.1
A small-animal single photon emission computed tomography (SPECT) system having compact size and low cost was designed using monolithic LGSO scintillation crystals and micro parallel-hole collimators through Monte Carlo simulations. A spatial resolution of 1 mm and a sensitivity of 100 cps/MBq were achieved with a four-head SPECT system. A hot rod with a diameter of 1.0 mm was resolved in the SPECT image of the ultra-micro hot spot phantom. Using a thin monolithic crystal and micro collimator, we achieved high spatial resolution and high sensitivity.
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Study on Effect of Changing RVSI on Colour Appearance
Shinichi Oyama,Mikiko Kawasumi 한국색채학회 2017 AIC 2017 Jeju Vol.2017 No.10
The aim of this research is to investigate an effect on colour appearance by changing Recognized Visual Space of Illumination (RVSI). According to a recent study, it was said that RVSI affects chroma the most among the three colour parameters of hue, value, and chroma. This paper examines three parameter values of the Munsell Colour System for the surface colour of an automotive part under the two different RVSI. In this experiment, subjects were asked to indicate its colour appearance using the Colour Matching Method with Japanese Industrial Standards colour chart, and the colour difference was compared on the three parameters between the two RVSI. The twenty-one colour variations were prepared for this experiment, and each dependency on the automotive colour was also examined at same time. As a result, it was confirmed that the difference in chroma was the largest among the three colour parameters. Additionally, this tendency on the automotive colour was more apparent on warm hues. The difference came larger on dark and/or vivid parts. In the future we can propose a new colour conversion system utilizing the results, and it will be helpful for colour designers and consumers to confirm the colour of a product.
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