Papers by Nobuyuki Kanematsu
Radiological physics and technology, Feb 3, 2024
Anticancer Research, Jun 23, 2023
Radiological Physics and Technology, Aug 11, 2021
A preliminary design of a compact heavy-ion injector for medical synchrotrons was presented. The ... more A preliminary design of a compact heavy-ion injector for medical synchrotrons was presented. The compact injector consists of the Radio-Frequency-Quadrupole (RFQ) linac and Interdigital H-mode (IH) Drift-Tube-Linac (DTL). For the IH-DTL, Alternating-Phase-Focusing (APF) method will be applied. The electric field distribution of the IH cavity was calculated with a threedimensional electromagnetic field solver and used for the simulations on the beam dynamics. By performing iterative calculations of the electric field and beam dynamics, the satisfactory emittance and acceptance were obtained. The compact injector will be constructed, and their beam test will be performed by the end of FY2005.
The new carbon-therapy facility has been constructed at Gunma University since April 2006, based ... more The new carbon-therapy facility has been constructed at Gunma University since April 2006, based on the design study and R&D works at HIMAC. As a future plan for the HIMAC, further, a new treatment facility was initiated at NIRS from April 2006.
Neurourology and Urodynamics, Apr 14, 2022
PurposeFew studies have examined the effects of body position on urination efficiency morphologic... more PurposeFew studies have examined the effects of body position on urination efficiency morphologically. We aimed to dissect out the anatomical changes of pelvic organs during urination in the upright and supine positions by a real‐time magnetic resonance imaging (rtMRI) system.MethodsThirteen healthy male volunteers aged 26–60 years were included in the study. The sagittal real‐time two‐dimensional images were taken to evaluate urinary efficiency, along with change in six morphological indices at the time of storage and the beginning of voiding, in both upright ant supine positions.ResultsUrination was more efficient in upright position than in supine position, as expressed by higher average rate of bladder emptying (9.9 ± 4.2 vs. 6.8 ± 2.9 ml/s, p < 0.05) and also by fewer participants showing significant residual urine (1/13 vs. 7/13, p < 0.05). At the onset of voiding in standing position, the levator ani (LA) muscle moves downward and backward followed by descent of the bladder neck and rotation of the prostate around the symphysis. Such changes were expressed by two morphological indices. One was posterior vesicourethral angle at the start of voiding, 152 ± 7 versus 140 ± 1 in upright and supine position (p < 0.05). The other index was the change in angle between the LA line and pubo‐coccygeal line in upright and supine position, 9.4 ± 9.9 versus 1.6 ± 7.9 before voiding (p < 0.05) and 30.2 ± 14.0 versus 17.3 ± 12.9 after the start of voiding (p < 0.05).ConclusionThe dynamic relaxation of LA seemed to be a key movement that enables more efficient urination in standing position than in supine position.
Physics Letters B, Sep 1, 1991
A search for the production of charged scalars has been carried out in e+e-annihilation at center... more A search for the production of charged scalars has been carried out in e+e-annihilation at center of mass energies up to 64 GeV with 61.1 pb-' of integrated luminosity using the VENUS detector at TRISTAN. The assumptions concerning the production and decay of hypothetical charged scalars are minimal; they are expected to be singly charged and decay into a pair of fermions. No positive evidence for their production has been found in a study of all combinations of the i!v(PO) and UD(UD) decay channels. We have excluded the mass region of 8.0-20.0 GeV/c' regardless of the decay mode.
Physics Letters B, Jun 1, 1988
We have studied inclusive lepton production in e+e-annihilations into multihadrons in the energy ... more We have studied inclusive lepton production in e+e-annihilations into multihadrons in the energy range between $= 50 and 55 GeV using the VENUS detector at TRISTAN, KEK. Though MARK-J and JADE groups at PETRA found an excess of isolated muon events at ,,&a 46.3 GeV, we have not observed such an anomaly in muon nor in electron production. The observed rates of isolated leptons are consistent with the production and decay of five known quarks.
International Journal of Urology, Jun 12, 2022
Carbon‐ions are charged particles with a high linear energy transfer, and therefore, they make a ... more Carbon‐ions are charged particles with a high linear energy transfer, and therefore, they make a better dose distribution with greater biological effects on the tumors compared with photons and protons. Since prostate cancer, renal cell carcinoma, and retroperitoneal sarcomas such as liposarcoma and leiomyosarcoma are known to be radioresistant tumors, carbon‐ion radiotherapy, which provides the advantageous radiobiological properties such as an increasing relative biological effectiveness toward the Bragg peak, a reduced oxygen enhancement ratio, and a reduced dependence on fractionation and cell‐cycle stage, has been tested for these urological tumors at the National Institute for Radiological Sciences since 1994. To promote carbon‐ion radiotherapy as a standard cancer therapy, the Japan Carbon‐ion Radiation Oncology Study Group was established in 2015 to create a registry of all treated patients and conduct multi‐institutional prospective studies in cooperation with all the Japanese institutes. Based on accumulating evidence of the efficacy and feasibility of carbon‐ion therapy for prostate cancer and retroperitoneal sarcoma, it is now covered by the Japanese health insurance system. On the other hand, carbon‐ion radiotherapy for renal cell cancer is not still covered by the insurance system, although the two previous studies showed the efficacy. In this review, we introduce the characteristics, clinical outcomes, and perspectives of carbon‐ion radiotherapy and our efforts to disseminate the use of this new technology worldwide.
Physics Letters B, Jun 1, 1994
We have studied single photon production in e +e-annihilation based on a data sample correspondin... more We have studied single photon production in e +e-annihilation based on a data sample corresponding to an integrated luminosity of 164.1 pb-~ at V~s = 58 GeV. The single photon yield is consistent with the prediction of the standard model with three light neutrino species. No anomalous signal has been observed. From this result left-and right-handed scalar electrons in the mass degenerate case are excluded at 90% CL below 44.4 GeV/c 2 for the massless photino.
Physics Letters B, 1990
Supersymmetric partners of charged leptons, scalar leptons were searched for in e+e-collisions at... more Supersymmetric partners of charged leptons, scalar leptons were searched for in e+e-collisions at TRISTAN with center-ofmass energies up to 60.8 GeV. The pair production of unstable scalar leptons were searched for among identified lepton-pair events, and stable ones among collinear two-track events. No evidence was found for them. Mass limits are presented for both large-splitting and degenerate cases.
Physics Letters B, Apr 1, 1992
We have measured the forward-backward charge asymmetry in the process of b-quark production in e+... more We have measured the forward-backward charge asymmetry in the process of b-quark production in e+e- annihilation at TRISTAN. It was made possible by detecting prompt leptons from b-quarks. The obtained asymmetry is A= -0.55+/-0.15+/-0.08. If corrected for B-meson mixing effects with the assumptions given in the text, the asymmetry becomes A=f-0.78+/-0.21+/-0.11, which is consistent with the prediction of the standard
Physics in Medicine and Biology, Nov 27, 2015
In treatment planning for proton radiotherapy, the dose measured in water is applied to the patie... more In treatment planning for proton radiotherapy, the dose measured in water is applied to the patient dose calculation with density scaling by stopping power ratio [Formula: see text]. Since the body tissues are chemically different from water, this approximation may cause dose calculation errors, especially due to differences in nuclear interactions. We proposed and validated an algorithm for correcting these errors. The dose in water is decomposed into three constituents according to the physical interactions of protons in water: the dose from primary protons continuously slowing down by electromagnetic interactions, the dose from protons scattered by elastic and/or inelastic interactions, and the dose resulting from nonelastic interactions. The proportions of the three dose constituents differ between body tissues and water. We determine correction factors for the proportion of dose constituents with Monte Carlo simulations in various standard body tissues, and formulated them as functions of their [Formula: see text] for patient dose calculation. The influence of nuclear interactions on dose was assessed by comparing the Monte Carlo simulated dose and the uncorrected dose in common phantom materials. The influence around the Bragg peak amounted to -6% for polytetrafluoroethylene and 0.3% for polyethylene. The validity of the correction method was confirmed by comparing the simulated and corrected doses in the materials. The deviation was below 0.8% for all materials. The accuracy of the correction factors derived with Monte Carlo simulations was separately verified through irradiation experiments with a 235 MeV proton beam using common phantom materials. The corrected doses agreed with the measurements within 0.4% for all materials except graphite. The influence on tumor dose was assessed in a prostate case. The dose reduction in the tumor was below 0.5%. Our results verify that this algorithm is practical and accurate for proton radiotherapy treatment planning, and will also be useful in rapidly determining fluence correction factors for non-water phantom dosimetry.
Zeitschrift Für Physik C Particles And Fields, Mar 1, 1990
between l/s= 50 and 60.8 GeV with the VENUS detector at TRISTAN. The average total cross section ... more between l/s= 50 and 60.8 GeV with the VENUS detector at TRISTAN. The average total cross section and the forward-backward charge asymmetry for #-pair production are observed to be 28.3_+1.4_+0.8pb and (-29.0+45f_+0.5)%, and those for z-pair production are _ _-32.8_6:2-/-1.5)~ at (lfs) 27.6 + 1.7 + 1.0 pb and (+ 6 4 = 56.9 GeV. These values are consistent with the predictions of the standard model of electroweak interactions.
Physics Letters B, Dec 1, 1989
A charge asymmetry has been measured in hadron jets from e +e-annihilation at energies between 52... more A charge asymmetry has been measured in hadron jets from e +e-annihilation at energies between 52 and 61.4 geV ((x/s) = 57.6 GeV). The measured asymmetry is A = 11.4% + 2.2% + 2.1% and is consistent with the prediction of the standard model of the electroweak theory. By using the differential cross section, lower limits of the compositeness scale in eeqq contact interactions have been determined to be typically a few TeV at 95% CL.
This work addresses computing techniques for dose calculations in treatment planning with proton ... more This work addresses computing techniques for dose calculations in treatment planning with proton and ion beams, based on an efficient kernel-convolution method referred to as grid-dose spreading (GDS) and accurate heterogeneity-correction method referred to as Gaussian beam splitting. The original GDS algorithm suffered from distortion of dose distribution for beams tilted with respect to the dose-grid axes. Use of intermediate grids normal to the beam field has solved the beam-tilting distortion. Interplay of arrangement between beams and grids was found as another intrinsic source of artifact. Inclusion of rectangular-kernel convolution in beam transport, to share the beam contribution among the nearest grids in a regulatory manner, has solved the interplay problem. This algorithmic framework was applied to a tilted proton pencil beam and a broad carbon-ion beam. In these cases, while the elementary pencil beams individually split into several tens, the calculation time increased only by several times with the GDS algorithm. The GDS and beamsplitting methods will complementarily enable accurate and efficient dose calculations for radiotherapy with protons and ions.
Hypothesis / aims of study Uroflowmetry is quite a useful and non-invasive examination to assess ... more Hypothesis / aims of study Uroflowmetry is quite a useful and non-invasive examination to assess the status of urination. Nomogram of peak flow rate and average flow rate according to urine volume has been established. However, the normal time-course of flow rate, represented by shapes of uroflow curve, has not yet been discussed, although a “bell shape” is generally believed normal especially in the pediatric area. We investigated to elucidate the normal shapes of uroflow curves of adult men.
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Papers by Nobuyuki Kanematsu