Kiyoshi Yoda

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PURPOSE. Recently, Elekta has supplied volumetric modulated arc therapy (VMAT) in which multi-leaf collimator (MLC) shape, jaw position, collimator angle, and gantry speed vary continuously during gantry rotation. A quality assurance procedure for VMAT delivery is described. METHODS AND MATERIALS. A single-arc VMAT plan with 73 control points (CPs) and(More)
We propose a clinical workflow of stereotactic volumetric modulated arc therapy (VMAT) for a lung tumor from planning to tumor position verification using 4D planning computed tomography (CT) and 4D cone-beam CT (CBCT). A 4D CT scanner, an Anzai belt and a BodyFix were employed to obtain 10-phase respiratory-correlated CT data for a lung patient under(More)
Three-dimensional tumor position during rotational dose delivery was evaluated by acquiring in-treatment kilovoltage (kV) cone-beam CT (CBCT) to ensure treatment quality. The CBCT projection data of a phantom were acquired during rotational megavoltage (MV) dose delivery up to 6 Gy to evaluate image quality under MV beam irradiation. A lung tumor patient(More)
PURPOSE A coefficient of a treatment margin model for anisotropic systematic positioning errors has been calculated in Cartesian coordinate system based on van Herk's analytical formulation. METHODS Three-dimensional (3D) patient population distribution was formulated in Cartesian coordinate system to model anisotropic systematic positioning errors.(More)
We have successfully created a single arc volumetric modulated arc therapy (VMAT) plan for treating post-surgical left breast/chest wall and regional nodes using Elekta multileaf collimator (MLC). Dose volume histograms (DVHs) were compared between the VMAT plans and conventional tangential beam plans using a field-in-field technique, leading to significant(More)
We have proposed four dimensional (4D) digitally reconstructed radiography (DRR) for verifying a lung tumor position during volumetric modulated arc therapy (VMAT). An internal target volume (ITV) was defined based on two clinical target volumes (CTVs) delineated on maximum exhalation and maximum inhalation images acquired by 4D planning computed tomography(More)
Localization and verification of a tumor position was conventionally performed prior to radiotherapy. The present authors, in the past a few years, proposed in-treatment verification of the tumor position by simultaneously acquiring cone beam computed tomography (CBCT) data using an on-board kilovolt imaging system. Dose delivery was either rotational(More)
To the Editor, Volumetric modulated arc therapy (VMAT) serves as a means for stereotactic hypofractionated treatment of lung tumors [1]. The present authors proposed an efficient VMAT sequence by restricting leaf speeds of a multi-leaf collimator per gantry rotation angle to below 1 mm/degree, thereby reducing the dose delivery time down to 210 s for a D95(More)
UNLABELLED Little has been reported on the errors of setup and daily organ motion that occur during radiation therapy (RT) for esophageal cancer. The purpose of this paper was to determine the margins of esophageal motion during RT. METHODS AND MATERIALS The shift of the esophagus was analyzed in 20 consecutive patients treated with RT for esophageal(More)