Hokkaido University Collection of Scholarly and Academic Papers
(65.351 recursos)
HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.
2.
超高エネルギー用高空間分解能・高感度コリメータの設計について - 久保, 直樹
小型被写体用超高エネルギー用コリメータの設計と作製を行った．作製したピンホールコリメータは，径0.6 mmで許容角度は13°であった．このピンホールから被写体までの距離と幾何学的感度，および距離と視野サイズの関係を計算した．次にガンマカメラに装着して18Fにおける総合空間分解能と総合感度を測定した．また超高エネルギー用コンバージングコリメータも設計した．ピンホールコリメータの計算結果は，距離を近づけると幾何学的感度は高くなったが，視野は狭まった． 測定した結果においてFWHMは2.4 mm，FWTMは9.5 mm，総合感度は6.8 counts sec –1 MBq–1であった．一方，コンバージングコリメータは視野の大きさの制限，視野周辺部の感度低下を受けないことが示唆された．このようにピンホールコリメータで超高エネルギーの高空間分解能撮像に成功した．またコンバージングコリメータの方は，臨床機への応用も可能と考えられた．
Recently, small object imaging using positron emitters, such as fluorine-18-2-deoxyglucose, has focused on basic nuclear medicine techniques. We have designed and developed ultra-high-energy high-resolution collimators for small object imaging. Firstly, we produced an ultra-high-energy pinhole collimator. The thickness of the lead shielding was 30 mm. The pinhole diameter of knife-edge aperture was 0.6 mm. The acceptance angle was 13°. This cylinder was equipped with a non-collimator gamma camera at a distance of 30.5 cm. The radius of rotation was 6 cm and the magnification was 5.1 times. In simulation calculations, as the...
5.
Evaluating performance of a pixel array semiconductor SPECT system - Kubo, Naoki; Zhao, Songji; Fujiki, Yutaka; Kinda, Akiyoshi; Motomura, Nobutoku
Objectives: Small animal imaging has recently been focused on basic nuclear medicine. We have
designed and built a small animal SPECT imaging system using a semiconductor camera and a
newly designed collimator. We assess the performance of this system for small object imaging.
Methods: We employed an MGC1500 (Acrorad Co.) camera including a CdTe semiconductor. The
pixel size was 1.4 mm/pixel. We designed and produced a parallel-hole collimator with 20-mm hole
length. Our SPECT system consisted of a semiconductor camera with the subject holder set on an
electric rotating stage controlled by a computer. We compared this system with a conventional small
animal SPECT system comprising a...
6.
Activation of connective tissue growth factor gene by the c-Maf and Lc-Maf transcription factors - Omoteyama, Kazuki; Ikeda, Hiromi; Imaki, Junko; Sakai, Masaharu
The Maf family of transcription factors is expressed during development of various
organs and tissues, and is involved in a variety of developmental and cellular differentiation
processes. We previously found that c-maf and mafB are strongly expressed in hypertrophic
chondrocytes during cartilage development. Connective tissue growth factor (CTGF) is also
expressed in hypertrophic chondrocytes. Adenovirus mediated introduction of c-maf gene into
the mouse fibroblast cell line C3H10T1/2 strongly induced CTGF expression. CTGF can be
induced by TGF-β via the SMAD pathway; however, the c-Maf could not induce TGF-β, nor
could TGF-β induce the c-Maf, suggesting that activation of CTGF by Maf is TGF-β
independent. Reporter transfection analysis using...
7.
An ultra-high-energy collimator for small animal imaging in dual-isotope study of 18F and 99mTc - Kubo, Naoki; Zhao, Songji; Kinda, Akiyoshi; Motomura, Nobutoku; Katoh, Chietsugu; Kuge, Yuji; Tamaki, Nagara
We have developed a pinhole collimator for small animal imaging using dual-isotopes, such as gamma and positron emitters. A lead cylinder containing a pinhole was placed around the subject (a small animal). The cylinder was equipped with a non-collimator gamma camera, and dual-isotope (99mTc-MIBI and 18F-FDG) SPECT was performed on a Wistar King Aptekman/hok (WKAH) rat. System planar sensitivity and Full-Width at Half-Maximum (FWHM) were measured for each radionuclide. System planar sensitivities for 99mTc and 18F SPECT were 2 and 7 cps/MBq, respectively. FWHMs for 99mTc and 18F SPECT were 2.0±0.5 and 2.7±0.5 mm, respectively. The collimator is relatively light...
9.
A new dynamic myocardial phantom for the assessment of left ventricular function by gated single-photon emission tomography. - Kubo, Naoki; Morita, Koichi; Katoh, Chietsugu; Shiga, Tohru; Konno, Masanori; Tsukamoto, Eriko; Morita, Yutaka; Tamaki, Nagara
Gated myocardial perfusion single-photon emission tomography (SPET) has been used for the measurement of left ventricular (LV) function and validated by means of comparison with other imaging modalities. We have designed a new dynamic myocardial phantom in order to validate the LV function as assessed by the use of gated myocardial perfusion SPET. The phantom consists of two half-ellipsoids (an endocardial surface and an epicardial surface) and a thorax. The myocardial space is filled with a radioactive solution. The endocardial surface moves continuously towards and away from the epicardial surface in the longitudinal axis to vary the LV volume [143...
10.
Optical emission diagnostics of H2+CH4 50-Hz–13.56-MHz plasmas for chemical vapor deposition - Shimozuma, Mitsuo; Tochitani, Gen; Tagashira, Hiroaki
The emission spectra of H2+CH4 plasmas excited at 50 Hz–13.56 MHz were measured. The emission intensity ratios of Hα/H*2 (3Σg→3Σu) from H2+CH4 plasma at 50 Hz and 13.56 MHz were about 0.7 and 0.05, respectively. The electron temperature was obtained from the two-line radiance ratio method using the Balmer lines (Hα and Hβ), and rapidly decreased with an increase above 200 kHz. The electron temperature for H2+CH4 plasma is 16 000 K at 1 kHz and 8200 K at 13.56 MHz. The plasma-maintaining voltages for H2 and H2+CH4 mixtures were also measured. The maintaining voltages were constant below 200 kHz,...
12.
Hydrogenated amorphous carbon films deposited by low-frequency plasma chemical vapor deposition at room temperature - Shimozuma, M.; Tochitani, G.; Ohno, H.; Tagashira, H.; Nakahara, J.
Provides information on hydrogenated amorphous carbon films prepared at room temperature by low frequency plasma chemical vapor deposition using methane and hydrogen. Measurement of resistivity and breakdown electric field after deposition; Infrared absorption spectrum of the grown film for the carbon-hydrogen stretching mode region; Raman spectroscopy using argon laser excitation.
13.
Boltzmann equation description of electron transport in an electric field with cylindrical or spherical symmetry - Date, H.; Shimozuma, M.
The spatially dependent description of the electron kinetics in nonuniform electric fields is of primary importance for the modeling of gas-filled proportional counters and other plasma devices. For a typical example, the amplification of the gain signal in the gas counters is determined by the behavior of electron ionization processes in the cylindrically or spherically symmetric electric field around thin wire or tiny sphere anode. In this paper, the general formalism of the Boltzmann equation in these types of the nonuniform electric fields is presented for specifying the electron swarm dynamics affected by the field geometry. The behavior of electrons...
14.
Inelastic collision processes of low energy protons in liquid water - Date, H.; Sutherland, K.L.; Hayashi, T.; Matsuzaki, Y.; Kiyanagi, Y.
Production probabilities of ions and excited particle species along the proton beam track in liquid water are estimated around the Bragg peak region, taking into account charge-changing processes and energetic secondary electron (δ-ray) behavior. Ionization and excitation processes are divided into two categories in this study: primary processes associated with direct proton (or hydrogen) interaction and secondary processes arising from the electrons ejected by the primary process. We show that the number of events in the secondary processes producing ions and excited particles is larger than that of the primary processes around the Bragg peak while neutralized protons (i.e., hydrogen)...
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