Formulation of objective indices to quantify machine failure risk analysis for interruptions in radiotherapy

Objectives: To evaluate the effect of interruption in radiotherapy due to machine failure in patients and medical institutions using machine failure risk analysis (MFRA). Material and methods: The risk of machine failure during treatment is assigned to three scores (biological effect, B; occurrence, O; and cost of labor and repair parts, C) for each type of machine failure. The biological patient risk (BPR) and the economic institution risk (EIR) are calculated as the product of B and O (B×O) and C and O (C×O), respectively. The MFRA is performed in two linear accelerators (linacs). Result: The multileaf collimator (MLC) fault has the highest BPR and second highest EIR. In particular, TrueBeam has a higher BPR and EIR for MLC failures. The total EIR in TrueBeam was significantly higher than that in Clinac iX. The minor interlock had the second highest BPR, whereas a smaller EIR. Meanwhile, the EIR for the LaserGuard fault was the highest, and that for the monitor chamber fault was the second highest. These machine failures occurred in TrueBeam. The BPR and EIR should be evaluated for each linac. Further, the sensitivity of the BPR, it decreased with higher T1=2 and α/β values. No relative difference is observed in the BPR for each machine failure when T1=2 and α/β were varied. Conclusion: The risk faced by patients and institutions in machine failure may be reduced using MFRA. Advances in knowledge: For clinical radiotherapy, interruption can occur from unscheduled downtime with machine failures. Interruption causes sublethal damage repair. The current study evaluated the effect of interruption in radiotherapy owing to machine failure on patients and medical institutions using a new method, that is, machine failure risk analysis

Dose compensation based on biological effectiveness due to interruption time for photon radiation therapy

Objective:To evaluate the biological effectiveness of dose associated with interruption time; and propose the dose compensation method based on biological effectiveness when an interruption occurs during photon radiation therapy. Methods:The lineal energy distribution for human salivary gland tumor was calculated by Monte Carlo simulation using a photon beam. The biological dose (Dbio) was estimated using the microdosimetric kinetic model. The dose compensating factor with the physical dose for the difference of the Dbio with and without interruption (Δ) was derived. The interruption time (τ) was varied to 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 75, and 120 min. The dose per fraction and dose rate varied from 2 to 8 Gy and 0.1 to 24 Gy/min, respectively. Results:The maximum Δ with 1 Gy/min occurred when the interruption occurred at half the dose. The Δ with 1 Gy/min at half of the dose was over 3% for τ >= 20 min for 2 Gy, τ = 10 min for 5 Gy, and τ = 10 min for 8 Gy. The maximum difference of the Δ due to the dose rate was within 3% for 2 and 5 Gy, and achieving values of 4.0% for 8 Gy. The dose compensating factor was larger with a high dose per fraction and high-dose rate beams. Conclusion:A loss of biological effectiveness occurs due to interruption. Our proposal method could correct for the unexpected decrease of the biological effectiveness caused by interruption time. Advances in knowledge:For photon radiotherapy, the interruption causes the sublethal damage repair. The current study proposed the dose compensation method for the decrease of the biological effect by the interruption

Semiconductor Thermal Neutron Detector

The  CdTe  and  GaN  detector  with  a  Gd  converter  have  been developed  and  investigated  as  a  neutron  detector  for neutron  imaging.  The  fabricated  Gd/CdTe  detector  with  the  25  mm  thick  Gd  was  designed  on  the  basis  of  simulation results  of  thermal  neutron  detection  efficiency  and  spatial  resolution.  The  Gd/CdTe  detector  shows  the  detection  of neutron  capture  gamma  ray  emission  in  the  155Gd(n,  g)156Gd,  157Gd(n,  g)158Gd  and  113Cd(n,  g)114Cd  reactions  and characteristic X-ray emissions due to conversion-electrons generated inside the Gd film. The observed efficient thermal neutron detection with the Gd/CdTe detector shows its promise in neutron radiography application. Moreover, a BGaN detector has also investigated to separate neutron signal from gamma-ray clearly. Keywords: detector, neutron, semiconductor, therma

A Case of Miller-Fisher Syndrome with Syndrome of Inappropriate Secretion of Antidiuretic Hormone

We report a 72-year-old woman with Miller-Fisher syndrome (MFS) with syndrome of inappropriate secretion of antidiuretic hormone (SIADH). She developed diplopia and unsteady gait a week after an upper respiratory infection. Neurologic examination revealed ophthalmoplegia, ataxia, symmetrical weakness, numbness, and areflexia. She underwent intravenous immunoglobulin therapy. Her serum sodium concentration decreased to 119 mEq/L on day 12. She had low plasma osmolarity (254 mosm/kg), high urine osmolarity (457 mosm/kg), and high urine sodium level (73 mEq/L), while the blood level of antidiuretic hormone was normal. Anti-GD1b immunoglobulin G (IgG), -GQ1b IgG, -GT1a IgG, and -Gal-C IgM antibodies were positive. We diagnosed her with MFS overlapping with SIADH. Four weeks after onset, her symptoms recovered. The elevation of anti-GD1b, -GQ1b, and -GT1a antibodies that recognize disialosyl residue may be pathologically related to SIADH

Platelets Strongly Induce Hepatocyte Proliferation with IGF-1 and HGF In Vitro

Background. It is well known that platelets have athrombotic effect. However, platelets play an importantrole not only in hemostasis but also in woundhealing and tissue regeneration. Platelets have beenreported to accumulate in the liver and promote liverregeneration after an extended hepatectomy, but themechanism is unclear. The present study was designedto clarify the mechanism by which plateletshave a direct proliferative effect on hepatocytes invitro.Materials and methods. Hepatocytes obtained frommale BALB/c mice by collagenase digestion and immortalizedhepatocytes (TLR2) were used. To elucidatethe mechanism of the proliferative effect of platelets,DNA synthesis of hepatocytes was measuredunder various conditions and the related cellular signalswere analyzed. Chromatographic analysis wasalso performed to clarify which elements of plateletshave mitogenic activity.Results. DNA synthesis significantly increased in thehepatocytes cultured with platelets (P < 0.001). However,when the platelets and hepatocytes were separated,the platelets did not have a proliferative effect.Whole disrupted platelets, the supernatant fraction,and fresh isolated platelets had a similar proliferativeeffect, while the membrane fraction did not. After theaddition of platelets, both Akt and extracellularsignal-regulated kinases ERK1/2 were activated, butextracellular signal-regulated kinase STAT3 was not activated. Some mitogenic fractions were obtainedfrom the platelet extracts by gel exclusion chromatography;the fractions were rich in hepatocyte growthfactor and IGF-1.Conclusions. Direct contact between platelets andhepatocytes was necessary for the proliferative effect.The direct contact initiated signal transduction involvedin growth factor activation. Hepatocyte growthfactor, vascular endothelial growth factor, and insulin-like growth factor-1, rather than platelet-derivedgrowth factor, mainly contributed to hepatocyteproliferation

X-Ray Analysis Literatures 2010

本総説は，2010年に学術雑誌に掲載されたX線分析関連の論文において，注目すべき論文を厳選し紹介する．調査した学術雑誌は19件（和雑誌2件含む）であり，X線分析の発展に寄与しているものを対象としているが，分析化学の分野だけでなく，分光学や物理学の分野も網羅している．各雑誌に関して，X 線分析手法や測定された試料の傾向，分析技術や要素開発に関するトピックスの他に，特筆すべき論文には論評も記している．日本工業規格（JIS）におけるX線分析関連の規格の制定や改訂についてまとめている．X線関連メーカーのウェブサイトを紹介し，掲載している技術レポートの情報も得られる．　In this article, the interesting X-ray analysis-related literatures, which are published on academic journals during the year 2010, are summarized. The number of the researched journals is 19, including two Japanese journals, which contribute the advance of the X-ray analysis in the field not only of analytical chemistry but also of spectroscopy and physics. In every journal, the trend of the X-ray analysis methods and of the measured specimens, the topics of analytical technique and of the developed components of the X-ray analysis apparatus, and the comments for the nortable articles are mentioned. The constitution and revision of standards of X-ray analysis on Japanease Industrial Standard (JIS) are shown. The websites of the company related with X-ray tools or X-ray apparatus are also shown, and the information on technical reports is available