放射線エネルギーの違いによる喉頭癌における吸収線量の影響

We investigated the usefulness of Gafchromic MD-55 film (Nuclear Associates, Inc.) for measuring the radiation doses on the radiotherapy of laryngeal cancers. Since larynx has thin wedge-shaped structure in anterior neck adjacent to airway, the radiation doses to the lesion may be diminished because of build-up and build-down. So, the dose has been measured with conventional measuring systems such as thermoluminescent dosimetry (TLD). However, it was not possible to evaluate the dose distribution correctly using TLD, because it is impossible to float a TLD chip in an air cavity. In this study, we employed Gafchromic MD-55 film as a dosimeter, for it can be set on the area of interest and with a measurability of dose range of 3 to 100 Gy, though it has no energy dependency. And this radiometer is composition near the soft tissue of the human body. The dose distributions to larynx were investigated with this film using neck phantom under each radiation beam energy of 4, 6 and 10 MV x-rays. Our neck phantom is made from acrylic resin and simulates a normal larynx on the basis of image information of computed tomography (CT). Moreover we observed secondary build-up and build-down curves in tissue in the vicinity of air cavities, especially at 10 MV x-rays. These findings suggest that patients with TI-T2 glottic cancers with anterior commissure invasion may receive more effective treatment with 4 MV x-rays rather than with 6 MV and 10 MV x-rays.Tl声門癌に対して放射線治療を単独で行うのは確立している方法である｡しかし,頚部は解剖学的に複雑であり,前方に薄いⅤ字形で,喉頭が気道に隣接している構造を持つので,病巣への線量はbuild-upとbuild-downの影響による線量低下が生じることが考えられる｡すなわち,放射線エネルギーの選択が喉頭癌の局所的制御に影響を及ぼすと言える｡この影響は,より高い放射線エネルギーでは,それに伴いより強く起きるということが基礎実験にて報告されている｡また,それらの線量測定は,熱ルミネセンス線量計(TLD)のような従来の測定システムで測定されていた｡しかし,空気空洞へTLD を単体 で浮かせ線量を正確に測定し評価を行うのは困難である｡本研究において,我々は Gafchromic MD-55 film (Nuclear Associates, Inc.)を使用し測定した｡ Gafchromic MD-55 film は,フィルムタイプ線量計でありエネルギー依存性がなく,3～100 Gyを測定可能であり,アクリル製頸部ファントムの空気組織境界面及び,空洞部に線量計を容易に精度良く配置することが可能である｡また,この線量計は人体の軟部組織に近い組成である｡そこで, 4, 6および10MVの各エネルギーでこの線量計を用いてエネルギーの違いによる,頸部ファントムを用いて喉頭の線量評価を行った｡その結果,我々は,特に放射線エネルギー10MVで頸部ファントムにおける,前部組織-組織空洞境界面-空洞部の一連したbuild-upおよびbuild-downを線量計で評価することができた｡これらの研究の結果､前交連浸潤を有するT1-T2に相当する声門癌患者は,放射線エネルギー6MVおよび10MVではなく,4MVを用いることによって,より効果的な放射線治療を行えると推測できる

Image Evaluation of Free-breathing Navigator Echo and Triggered Cardiac-gated Delayed Myocardial Enhancement Magnetic Resonance Imaging in Sedated Infants

We validated a navigator-echo-triggered sequence that drives magnetization before cardiac-gated inversion recovery T1 turbo field echo acquisition, in the sedated free-breathing pediatric population. Cardiac magnetic resonance imaging was performed on sedated infants with single ventricle. We calculated the signal-to-noise ratios and contrast-to-noise ratios of 2 groups of images obtained using respiratory triggering with and without navigator echo. All images were then visually assessed by 2 observers. The signal-to-noise ratio and the contrast-to-noise ratio were significantly higher with than without navigator echo (p<0.01; p<0.05). The visual assessment scores were also consistently better with than without navigator echo (p<0.01). Free-breathing navigator echo was found to have the advantage of decreasing the motion artifact caused by respiration. Cardiacgated inversion recovery T1 turbo field echo sequence for free-breathing navigator-echo-triggered respiration allows for the acquisition, in sedated infants, of diagnostic images whose quality exceeds that of the non-navigator-echo-triggered alternative

Report of a study using phantom materials, and clinical experience with simultaneous radio-hyperthermotherapy.

Simultaneous radiohyperthermotherapy (SRH) is a combined hyperthermia-radiation therapy in which irradiation is given during heating. Mutual interference between the high energy radiotherapy system (Toshiba LMR-15A) and the 13.56 MHz capacitive heating system (Omron HEH-500C) was tested with phantom materials prior to a clinical trial with SRH. The energy and flatness of irradiation were not affected by the heating system within the range of clinical use. The high energy radiotherapy system did not affect the increase or distribution of temperature during simultaneous treatment. The results of this phantom study indicated that these apparatuses would not produce clinically significant mutual interference during SRH. A clinical trial was performed on a 57-year-old woman with postoperative recurrence of rectal cancer. This is the first reported clinical case treated with true SRH in which external irradiation was administered during mid capacitive heating. Twelve SRH treatments were performed on the recurrent lesion at a frequency of twice a week for six weeks using the apparatuses described above. There was a significant reduction in pain after treatment. The tumor marker carcinoembryonic antigen (CEA) level decreased after treatment. On CT images taken after treatment, the tumor site became a low density area which indicated necrosis. There were no side effects. These results suggest that further clinical study of SRH should be performed to clarify its advantages.</p

Bilayer Indium Tin Oxide Electrodes for Deformation-Free Ultrathin Flexible Perovskite Solar Cells

The superior electrical conductivity and optical transparency of indium tin oxide (ITO) make it an ideal electrode material for use in optoelectronic devices such as solar cells. When ITO electrodes are fabricated on very thin plastic substrates, however, the internal stress of the ITO layer causes the substrate to deform, severely limiting the device's performance. Herein, it is shown that ITO bilayers composed of an amorphous base layer and a crystalline overlayer lead to deformation-free ITO electrodes. It is shown that an optimized bilayer structure is achieved when the internal stresses of the amorphous and crystalline layers approximately cancel. With this approach, mixed composition metal halide perovskite solar cells with ITO electrodes are successfully fabricated on 4 μm polyethylene naphthalate films. A power conversion efficiency (PCE) of 18.2% is obtained for the reference cell design, corresponding to a power-to-weight ratio of 24 W g−1 before encapsulation. The devices retain 95% of the original PCE after 1000 bend cycles, while under simulated indoor lighting (white LED, 200 lux, 5000 K) the PCE reaches 28.3%. A 3-cell module with a designated area of 2.3 cm² is realized with a power output of 28.1 mW and an open-circuit voltage of 3.17 V

Suitability on the densitometry systematize in Laser Densitometer Model 1710 for Gafchromic MD-55-2 film

医療の高度化に伴い,放射線治療分野においても急速な技術革新が行われている｡QOL(Quality of Life)を考慮に入れた治療が求められる多くの場合,放射線治療が大きな選択肢の一つであることは言うまでもない｡このような状況下の中で,正常組織に影響を与えず病巣に限局した放射線を照射する技術が開発され,外照射においては,欧米に習い我が国でも研究段階から臨床へ移り変わろうとしている｡その際に,投与線量評価を欠かすことができないが,従来から使用されているいずれの線量計も新しい治療法に対応しきれていない｡そこで,フィルムタイプ線量計, Gafchromic MD-55-2 film の開発により,いくつかの問題が解決されてきている｡しかし,この線量計を精度良く測定する濃度測定器が必要になるが,現段階において規格化されたガイドラインが存在しないのが現状である｡そこで本研究では,当施設で保有しているⅩ線フィルム線量測定用 Laser Densitometer Model 1710 を用いて Gafchromic MD-55-2 fllm による線量測定を行い,問題点の抽出を行うとともに線量測定精度の考察を行った｡For the medical advancement, the speedy technical innovation is performed also in the radiotherapy. When patients can search for QOL (Quality of Life), the radiation therapy is one of the choices. The radiation therapy system for limited irradiation to lesion without affecting normal tissue has been developed over several years. On the technology of external irradiation in our country, the level is improving to clinical stage from study grade. In such things, a new requirement will come out also as for the measuring method of the medication dose. However, conventional various radiometers have many problems to the dosimetry of the new radiotherapy method. Gafchromic MD-55-2 film, which has new form of radiochromic film based on poly-diacetylene and has been introduced for medical applications recently, is expected to solve some problems. Now, in clinical usage of this film, there is no comprehensive guideline for densitometry system and it's calibration yet. So, in this paper, the densitometry of Gafchromic MD-55-2 film was performed with Laser Densitometer Model 1710 for general-purpose film dosimetry system. And then, problems in the densitometry were extracted and the accuracy of dosimetry was investigated

NK cells control tumor-promoting function of neutrophils in mice

Although NK cells are recognized as direct antitumor effectors, the ability of NK cells to control cancer-associated inflammation, which facilitates tumor progression, remains unknown. In this study, we demonstrate that NK cells control tumor-promoting inflammation through functional modification of neutrophils. NK cells control the tumor-promoting function of neutrophils through an IFNgamma-dependent mechanism. Tumor progression in an NK cell-depleted host is diminished when the IL17A-neutrophil axis is absent. In NK cell-depleted mice, neutrophils acquire a tumor-promoting phenotype, characterized by up-regulation of VEGF-A expression, which promotes tumor growth and angiogenesis. A VEGFR inhibitor which preferentially suppressed tumor growth in NK cell-depleted mice was dependent on neutrophils. Furthermore, the systemic neutropenia caused by an anti-metabolite treatment showed an anti-cancer effect only in mice lacking NK cells. Thus, NK cells likely control the tumor-promoting and angiogenic function of neutrophils

Total Skin Electron Beam Therapy

The peripherally T-cell lymphoma; Mycosis fungoides etc, has the good radiation sensitivity, and has been adapted for total skin electron beam therapy. In this study the pendular irradiation method was used for the purpose of total skin electron beam therapy in Mycosis fungoides, and physical data on the radiation field and the electron beam energy were useful clinically.皮膚に限局した一連の末梢型T細胞リンパ腫は放射線に対する感受性が高く、電子線治療の適応となる疾患である。こららの疾患は一般的に全身の皮膚に浸潤するため、治療に際してはTarget Volumeの深さに合わせた最小限のエネルギーで全身隈なく照射する必要がある。筆者等は最近臨床で遭遇した菌状息肉症の患者を治療するため、その患者に合った物理的なデータを測定した。照射野の拡大には振子照射法を用い、エネルギー低減方法は装置に装備されている鉛のスキャタラーを低原子番号で、しかも加工のしやすい塩化Vinyl板に交換する方法を工夫した。データとして治療効果、副作用に関係する線量率、エネルギー、及び照射野内平坦度について測定した結果、距離が長くなる関係から線量率が低下する全身照射法の欠点は解消できなかったが、エネルギー及び平坦度については使用可能なデータを得ることができた

Statistics and analysis on the troubles of linear accelarator.

放射線治療の成否は厳密に設定されたTarget Volumeに如何に正確な線量を照射するかによって決まる。治療術式の過程において、最も大きな誤差を生む要因は照射機器である。誤差の少ない治療を目指す第一歩は機器を正確に作動させることであり、日常からの保守点検および整備が必要である。今回、岡山大学附属病院で1976年から1991年までに使用されたリニアックについて、その故障状況を集計し、部位別故障件数、管球の寿命、稼動率などを分析検討した。その結果、故障件数では設置され稼動を始めた1976年、装置の老朽化が進んだ1990、1991年に多かった。部位別集計では加速部に圧倒的に多く、次いで照射口、高圧部の順であった。稼動率は設置年および1987年を除いてはいずれも96％以上とよい結果であった。この結果は全国に稼動している同型の装置の保守点検に役立つものと考える。The Accuracy of radiation dose exposed the rigidly selected target volume is one of significant factors that have an influence upon the efficiency of treatment in the radiotherapy techniques. Therefore, it is necessary to daily maintain and check irradiation equipment for the radiotherapy. For the radiotherapy, the electron linear accelerator, Toshiba LMR-15A, had worked from 1976 to 1991 in Okayama University Hospital. On this study, all records regarding the operating condition were analyzed concerning parts of trouble, life of a tube and operating efficiency for these sixteen years. In a high frequency of trouble, an accelerating structure ranked first, followed by a collimator and a high voltage generator. The operating efficiency was 95% or greater. This report should be helpful to maintain and check a same model in other hosptals

Photon background caused by the reduction of the electron beam energy - Materials of scattering foil -

The total skin electron beam therapy has been one of the clinical treatment for peripherally T-cell lymphoma; Mycosis fungoides, adult T-cell lymphoma, and so on. The crucial points in this treatment are not only having an optimum energy level of electron beam for a target volume (a tissue) but also keeping the photon back ground low. It is not easy to regulate those points by the control panel, however, for the equipment that is conventinally used for electron beam, theoretically, is to exchange lead (Pb), which is ordinarily used, to a low atomic number material as a scattering foil. We examined several different kinds and / or various thickness as a scattering foil material that can make the electron beam lower without an increase of the contaminant as X-ray. We hereby reported the results, and strongly suggested the following two materials in use; acrylic plate, carbon board, and so on, which are easily available and worked, would be practically useful for the total skin electron beam therapy

A new experimental system for irradiating tumors in mice using a linear accelerator under specific pathogen-free conditions.

We developed a reliable system for the irradiation of xenografted tumors in mice which allows for accurate local irradiation under specific pathogen-free conditions. The system presented here consists of acrylic supports for mice and an acrylic box connected to a pump through 0.22 microns pore-sized filters. Mice with xenotransplanted tumors growing on their right hind legs were set on the supports and put into the box in a laminar flow hood. The tumors of 7 mice were irradiated simultaneously with X-rays of 6 and 10 MV generated by a linear accelerator at a dose rate of 3.1-4.7 Gy/min. The air was ventilated through filters during irradiation in the closed box. Microorganism tests confirmed that no bacteria entered or left the box. One of the significant characteristics of this setup is that it allows for irradiation under conditions of acute hypoxia, which is obtained using an integrated tourniquet. The dose variation among 7 tumors was less than 1%. The rest of the mouse's body was shielded effectively by a half-field technique and a lead block. As a result, the whole body dose for the mice was 0-4% of the total dose absorbed by the tumor. Due to the high dose rate and the ability to irradiate 7 mice simultaneously under specific pathogen-free conditions, this new system can be considered a time-saving and valuable tool for radiation oncology research.</p