Appropriate margin for planning target volume for breast radiotherapy during deep inspiration breath-hold by variance component analysis

BACKGROUND: This study aimed to quantify errors by using a cine electronic portal imaging device (cine EPID) during deep inspiration breath-hold (DIBH) for left-sided breast cancer and to estimate the planning target volume (PTV) by variance component analysis. METHODS: This study included 25 consecutive left-sided breast cancer patients treated with whole-breast irradiation (WBI) using DIBH. Breath-holding was performed while monitoring abdominal anterior-posterior (AP) motion using the Real-time Position Management (RPM) system. Cine EPID was used to evaluate the chest wall displacements in patients. Cine EPID images of the patients (309, 609 frames) were analyzed to detect the edges of the chest wall using a Canny filter. The errors that occurred during DIBH included differences between the chest wall position detected by digitally reconstructed radiographs and that of all cine EPID images. The inter-patient, inter-fraction, and intra-fractional standard deviations (SDs) in the DIBH were calculated, and the PTV margin was estimated by variance component analysis. RESULTS: The median patient age was 55 (35-79) years, and the mean irradiation time was 20.4 ± 1.7 s. The abdominal AP motion was 1.36 ± 0.94 (0.14-5.28) mm. The overall mean of the errors was 0.30 mm (95% confidence interval: - 0.05-0.65). The inter-patient, inter-fraction, and intra-fractional SDs in the DIBH were 0.82 mm, 1.19 mm, and 1.63 mm, respectively, and the PTV margin was calculated as 3.59 mm. CONCLUSIONS: Errors during DIBH for breast radiotherapy were monitored using EPID images and appropriate PTV margins were estimated by variance component analysis

Paving ways to documenting an invisible linguistic minority in Japan: Ikema

This presentation introduces our collaborative project (involving researchers from Canada, Japan, and the U.S.) on the language of Ikema in Okinawa, Japan. We highlight the problems we encountered and our attempts to overcome them - a necessary step before engaging in “Documentary Linguistics” (Himmelmann 1998) on Ikema. Ikema is a typical endangered language: no longer acquired by children and only spoken by a decreasing number of older speakers. Islanders express concerns that their mother tongue is disappearing, but most feel that the move toward monolingualism in Standard Japanese is inevitable and even desirable. This is an expected outcome; although, linguistically speaking, Ikema and other Okinawan languages should be considered as constituting a separate language group, for many years the Japanese government treated them as merely ‘dialects’ of Japanese. The 1916 government initiative of homogenizing the nation by spreading Standard Japanese was so successful that ‘dialect’ speakers believe that they are speaking inferior versions of Japanese. In fact, remaining Ikema speakers still recall the infamous ‘dialect placards’, which were placed around their necks as a form of punishment when they used Ikema at school. It is thus not surprising that islanders initially showed suspicion and resistance when our team showed interest in Ikema. However, we soon started finding community leaders with concerns about their rapidly disappearing language. Through discussions with us, these leaders started to realize that documenting Ikema for future generations in collaboration with our group is a significant first step. We also recognized the importance of establishing our presence in the community through getting involved in local projects, e.g. a kindergarten teacher’s project of compiling booklets to promote Ikema for the community, and local activists’ attempt to archive and display a large number of precious photos taken by an ethnographer in the 1960’s. By participating in these projects, we have been slowly gaining the trust of the community, which, we hope, will take us to our eventual goal of conducting a large scale community-centered documentation project. In fact, more recently we have been provided with opportunities to record narratives by older speakers (80s-90s), and to work with younger speakers (60s-70s) in eliciting sentences. Knowing their difficult history and our genuine involvement with community activities have been critical in decreasing tensions which existed in the community. These tensions may continue to exist, but we need to keep paving ways toward documenting Ikema and hopefully other invisible minority languages in Okinawa

Crystallinity of In-Ga-Zn-oxide (IGZO) in CAAC-IGZO vertical FET

Oxide semiconductor field-effect transistors (OSFETs) are actively developed [1]. In particular, there are many reports on a typical oxide semiconductor, In-Ga-Zn oxide (IGZO) [2]. An OSFET is fabricated with a planar structure in many cases; however, a vertical FET (VFET) with a current path perpendicular to a substrate can be fabricated with an area overhead comparable to one trench hole, and is gathering attention [3]. The VFET structure enables OSFETs to be highly integrated, and also allows the resolution of displays to be higher. Please click Download on the upper right corner to see the full abstract

Impurity conduction in phosphorus-doped buried-channel silicon-on-insulator field-effect transistors

We investigate transport in phosphorus-doped buried-channel metal-oxide-semiconductor field-effect transistors at temperatures between 10 and 295 K. In a range of doping concentration between around 2.1 and 8.7 x 1017 cm-3, we find that a clear peak emerges in the conductance versus gate-voltage curves at low temperature. In addition, temperature dependence measurements reveal that the conductance obeys a variable-range-hopping law up to an unexpectedly high temperature of over 100 K. The symmetric dual-gate configuration of the silicon-on-insulator we use allows us to fully characterize the vertical-bias dependence of the conductance. Comparison to computer simulation of the phosphorus impurity band depth-profile reveals how the spatial variation of the impurity-band energy determines the hopping conduction in transistor structures. We conclude that the emergence of the conductance peak and the high-temperature variable-range hopping originate from the band bending and its change by the gate bias. Moreover, the peak structure is found to be strongly related to the density of states (DOS) of the phosphorus impurity band, suggesting the possibility of performing a novel spectroscopy for the DOS of phosphorus, the dopant of paramount importance in Si technology, through transport experiments.Comment: 9 figure

Independent calculation-based verification of volumetric-modulated arc therapy–stereotactic body radiotherapy plans for lung cancer

This study aimed to investigate the feasibility of independent calculation‐based verification of volumetric‐modulated arc therapy (VMAT)–stereotactic body radiotherapy (SBRT) for patients with lung cancer using a secondary treatment planning system (sTPS). In all, 50 patients with lung cancer who underwent VMAT‐SBRT between April 2018 and May 2019 were included in this study. VMAT‐SBRT plans were devised using the Collapsed‐Cone Convolution in RayStation (primary TPS: pTPS). DICOM files were transferred to Eclipse software (sTPS), which utilized the Eclipse software, and the dose distribution was then recalculated using Acuros XB. For the verification of dose distribution in homogeneous phantoms, the differences among pTPS, sTPS, and measurements were evaluated using passing rates of a dose difference of 5% (DD5%) and gamma index of 3%/2 mm (γ3%/2 mm). The ArcCHECK cylindrical diode array was used for measurements. For independent verification of dose‐volume parameters per the patient’s geometry, dose‐volume indices for the planning target volume (PTV) including D95% and the isocenter dose were evaluated. The mean differences (± standard deviations) between the pTPS and sTPS were then calculated. The gamma passing rates of DD5% and γ3%/2 mm criteria were 99.2 ± 2.4% and 98.6 ± 3.2% for pTPS vs. sTPS, 92.9 ± 4.0% and 94.1 ± 3.3% for pTPS vs. measurement, and 93.0 ± 4.4% and 94.3 ± 4.1% for sTPS vs. measurement, respectively. The differences between pTPS and sTPS for the PTVs of D95% and the isocenter dose were −3.1 ± 2.0% and −2.3 ± 1.8%, respectively. Our investigation of VMAT‐SBRT plans for lung cancer revealed that independent calculation‐based verification is a time‐efficient method for patient‐specific quality assurance

Transoral surgery for superficial head and neck cancer: National Multi‐Center Survey in Japan

Head and neck cancers, especially in hypopharynx and oropharynx, are often detected at advanced stage with poor prognosis. Narrow band imaging enables detection of superficial cancers and transoral surgery is performed with curative intent. However, pathological evaluation and real-world safety and clinical outcomes have not been clearly understood. The aim of this nationwide multicenter study was to investigate the safety and efficacy of transoral surgery for superficial head and neck cancer. We collected the patients with superficial head and neck squamous cell carcinoma who were treated by transoral surgery from 27 hospitals in Japan. Central pathology review was undertaken on all of the resected specimens. The primary objective was effectiveness of transoral surgery, and the secondary objective was safety including incidence and severity of adverse events. Among the 568 patients, a total of 662 lesions were primarily treated by 575 sessions of transoral surgery. The median tumor diameter was 12 mm (range 1–75) endoscopically. Among the lesions, 57.4% were diagnosed as squamous cell carcinoma in situ. The median procedure time was 48 minutes (range 2–357). Adverse events occurred in 12.7%. Life-threatening complications occurred in 0.5%, but there were no treatment-related deaths. During a median follow-up period of 46.1 months (range 1–113), the 3-year overall survival rate, relapse-free survival rate, cause-specific survival rate, and larynx-preservation survival rate were 88.1%, 84.4%, 99.6%, and 87.5%, respectively. Transoral surgery for superficial head and neck cancer offers effective minimally invasive treatment

日本語リメディアル教育 : 日本語文章能力開発演習の試行と成果の検証

近年、日本の大学生の学力低下が問題となり、大学生であるにもかかわらず高校程度の内容の復習から学習を始めざるを得ないという状況がある。さらに今後も日本社会の少子化や、それに伴う入学選抜試験の多様化等により大学生のリメディアル教育が必要となってくることが考えられる。そこで本稿では全ての学力の基礎となる日本語の効果的なリメディアル教育を行うための基礎的な手がかりを得るため、理系の大学での日本語リメディアルの実験授業を行い、リメディアル教育の効果的な方法について検証した。実験授業は理系の大学で3ヶ月行い、受験勉強的な問題を系統的に学習するドリル型コースと楽しく学んでもらうことを目指したアクティビティ型コースの2コースを実施した。これら2コースと授業を受けない統制群とでプリテストとポストテストを実施し成果を比較した。テストは受験用読解問題方式のリーディングテストと、簡単な指示で短い作文を書くライティングテストを行った。この結果、リーディングテストではドリル型コースでプリテストとポストテストで有意差が見られ成果が確認されたが、ライティングテストではアクティビティ型コースで顕著な成果が見られた。リーディングは3ヶ月程度の短期間ではわずかの伸びしか見られなかったが、ライティングは学習者の気づきを促し、動機を高めることができれば短期間でも効果が得られることがわかった。また、今後コンピュータを使ってのリメディアル教育の可能性もあるが、実験授業ではメンターの存在が学習者にとって重要であったことがわかったことから、コンピュータを導入する場合でも適当な指導者の指導が必要であると言える。Recently some Japanese universities and colleges experience problems with students who have a low level of Japanese language ability, especially in reading and writing. This paper reports the results obtained from experimental lessons at a university of engineering in order to provide information on the efficiency of Japanese remedial courses. Each student takes either of the two types of experimental lesson courses. These are the Drill Course, which involves ordinary drills mainly in reading, and the Activity Course, involving word-game-type tasks, including short writing assignments. Comparing the results of tests before and after the experimental lesson courses shows that the Drill Course is effective in improving the performance of reading tasks, while the Activity Course is highly effective in the performance of writing tasks but not for reading tasks. It is suggested that the improved performance of writing tasks can be developed in a rather short period, provided that the program can promote the participants1 awareness and motivation. It is also shown that mentors played pivotal roles in the lessons, and that advisors would probably necessary in case of computer-assisted-learning