Publications by authors named "Harumitsu Hashimoto"

Background/aim: This study aimed to evaluate the effect of intensity-modulated radiation therapy (IMRT) on the clinical outcomes of patients with lymph node (LN) oligo-recurrence and a controlled primary tumor.

Patients And Methods: We retrospectively reviewed the medical records of 21 patients diagnosed with LN oligo-recurrence who received IMRT with curative intent. Patients with tumor of various primary sites and histopathological types were included in this study.

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Intensity-modulated radiation therapy (IMRT) delivers an excellent dose distribution compared with conventional three-dimensional conformal radiation therapy (3D-CRT) for postoperative radiation including the lymph nodes in breast cancer patients. The TomoTherapy system, developed exclusively for IMRT, has two treatment modes: TomoDirect (TD) with a fixed gantry angle for beam delivery, and TomoHelical (TH) with rotational beam delivery. We compared the characteristics of TD with TH and 3D-CRT plans in the breast cancer patients.

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The purpose of this study was to quantify actual patient organ doses from megavoltage computed tomography (MVCT) using an MVCT beam model of a helical tomotherapy unit in a general treatment planning system (TPS). Dosimetric parameters (percentage depth dose, lateral beam profile, and longitudinal beam profile) of the MVCT beam were measured using Gafchromic EBT3 films (ISP Corporation, Wayne, NJ, USA) and used for beam modeling in a Pinnacle3 TPS (Philips, Amsterdam, Netherlands); this TPS is widely used with linear accelerators. The created beam model was adjusted and validated by assessing point doses in a cylindrical phantom in static and helical beam plans with fine, normal and coarse pitches.

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Introduction: Rectal bleeding after radiotherapy impacts the quality of life of long-term surviving prostate cancer patients. We sought to identify factors associated with late rectal bleeding following intensity modulated radiation therapy (IMRT) using TomoTherapy for prostate cancer.

Methods: We retrospectively analysed 82 patients with localised prostate cancer treated with TomoTherapy.

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In IMRT for prostate cancer, MU verification is performed by the actual measurement. We have experienced a remarkable improvement in results, once succeeding in finding out the more suitable and optimal evaluation dose point in some cases even though the deviation between a designed MU score and our actual record gained at the iso-center was more than 3%. In this study, we tried to demonstrate how much influence would be given to the point dose verification by the 3D arrangement between an ion chamber and tips of the MLC.

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The Stereotactic Body Frame, which was devised as a fastening unit for the irradiation of various truncal lesions, has obtained a good reputation for its high-precision reproductivity. This device is accessorized with 'Diaphragm Control', which can reduce the respiratory movement of intra-thoracic organs. In this study, to investigate the possibility of a respiratory monitor using our device, we try to clarify the relationship between the pressure against the abdominal board of 'Diaphragm Control' and each constrained tidal respiratory movement.

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The DD-System is a dose-distribution system for analyzing the film method with a general-purpose flatbed image scanner. By analyzing the analogue digital conversion(ADC)value of each pixel acquired by the DD-system, we examined the technical problems of measurement with the scanner when making a dose-density table. When film of uniform density was measured, the ADC values distributed normally.

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We found an artifact of the Stereotactic Body Frame's (SBF) indicators when we used diagnostic 16-row multi-detector computed tomography (MDCT) as a simulator. Stereotactic radiotherapy (SRT) requires the accuracy of each millimeter. However, a gap of 3 mm at the maximum along the Z axis was caused by this artifact.

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