Publications by authors named "Fumihiro Tomita"

Article Synopsis
  • - The study evaluates the accuracy and latency of the surface-guided radiotherapy (SGRT) system using TrueBeam and AlignRT, comparing beam characteristics between gated and nongated beams with minimal differences observed (<0.1%).
  • - Dynamic accuracy was generally high, with deviations of less than 1 mm for 10-mm shifts, although ROI shape played a significant role in the results, showing a maximum displacement of 1.9 mm for a 30-mm shift.
  • - Latency times varied based on frame rates, with some rates possibly exceeding guideline limits, highlighting the need for careful use of SGRT systems in clinical settings.
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Introduction: This study aimed to further understand the psychological distress associated with skin marking during radiotherapy among patients with breast cancer. The potential benefits of skin mark-free radiotherapy were also explored.

Materials And Methods: The study population included female breast cancer patients scheduled for radiation therapy and skin marking.

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Introduction Whole lung irradiation (WLI) is used for the treatment of lung metastasis in Wilms tumor and Ewing sarcoma; however, cardiac complications are one of the concerns. We report the dosimetric advantages of WLI using volumetric-modulated arc therapy (VMAT) and present a dosimetric comparison of VMAT with anteroposterior-posteroanterior (AP-PA) and static-field intensity-modulated radiation therapy (IMRT). Additionally, we evaluated the dosimetric impact of respiratory motion and intra-fractional motion during VMAT treatment.

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Purpose: To validate the point-A dose and dose distribution of metal and resin applicators in comparison with those of TG-43U1.

Methods: The metal and resin applicators consisting of tandem and ovoid were modeled by the egs_brachy. The doses to point A and dose distributions considering each applicator were calculated and compared to those of TG-43U1.

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This paper proposes a new concept of phantom development, along with the utilization of new materials that can reproduce lung morphology and density. A lung substitute phantom using microspheres was fabricated; then, its dosimetric utility in radiotherapy was investigated, during which the density was adjusted to closely resemble the morphology of the actual human lung. Microspheres were used to reproduce alveoli, which are the main components of the lung.

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In this study, we developed a mouthpiece-type gel dosimeter to prevent the oral mucositis caused by the perturbation effect of dental alloys in the radiotherapy of the head and neck regions and to enable in vivo dosimetry. Understanding the dose distribution in the oral cavity during radiotherapy helps identify the possible site for oral mucositis during treatment. Here agarose, which has a higher melting point than gelatin, was added as a coagulant to stabilize the shape of the dosimeter.

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Purpose: The incident electron energy spectrum was determined by an estimation formula based on the Lévy distribution in order to calculate the PDD and OAR that is consistent with the measurement.

Methods: EGSnrc was used to calculate PDD and OAR at nominal energies of 4, 6, 9, 12, and 15 MeV. The parameters for determining the incident electron energy spectrum were adjusted to be a reasonable value in the error between the measured and the calculated values.

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Temperature corrections are necessary to account for the varying mass of air in the cavity volume of a vented ionization chamber. The temporal response resulting from temperature changes in a cylindrical and/or Farmer-type ionization chamber, which is the standard dosimeter, has been thoroughly discussed by some researchers. The purpose of this study was to characterise and analyse the dependence of the cavity air temperature of the parallel-plate-type ionization chamber on changes in the ambient temperature.

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