Optimal combination of collimator angles for dual-arc volumetric modulated arc therapy planning in stereotactic body radiotherapy for spinal metastases.

In planning the treatment of spinal metastases using stereotactic body radiotherapy (SBRT), the optimal blocking of the spinal cord to match the leaf travel can be achieved with a first-arc collimator angle of approximately 90°. We aim to clarify the optimal second-arc collimator angles when the first-arc collimator angle is fixed to 90° in dual-arc volumetric modulated arc therapy (VMAT). For this retrospective study, we considered 37 spinal segments with spinal metastases and created dual-arc VMAT plans.

Multi-Institutional Study of End-to-End Dose Delivery Quality Assurance Testing for Image-Guided Brachytherapy Using a Gel Dosimeter.

Purpose: To quantify dose delivery errors for high-dose-rate image-guided brachytherapy (HDR-IGBT) using an independent end-to-end dose delivery quality assurance test at multiple institutions. The novelty of our study is that this is the first multi-institutional end-to-end dose delivery study in the world.

Materials And Methods: The postal audit used a polymer gel dosimeter in a cylindrical acrylic container for the afterloading system.

Radiation dose rate variations in different measurement scenarios after prostate I brachytherapy.

Purpose: This study aimed to directly compare different measurement scenarios using a supplemental radiation exposure measurement data set.

Materials And Methods: Two sets of measurement scenarios comparing different body postures, such as standing and chair sitting positions, and different measurement directions, such as anterior and posterior directions, were assessed for radiation dose rate variations in this study at the Tokyo Medical Center, Japan. The estimated precaution time for holding children in the spoon position while sitting was also calculated.

Assessing protection against radiation exposure after prostate (125)I brachytherapy.

Purpose: To expand the radiation dose rate measurement data set by measuring radiation under various prostate (125)I brachytherapy situations.

Methods And Materials: Measurements were obtained from 63 consecutive unselected patients at Tokyo Medical Center, Japan. Differences in factors during measurements, such as body postures, distances from the skin surface, and measurement directions were considered.

[Evaluation of therapeutic carbon-beam attenuation in inhomogeneous layered phantoms: Comparison with the present method using a water phantom.].

Carbon-beam therapy has been successfully carried out at HIMAC, Japan. This treatment offers two advantages over conventional radiation therapy: better dose concentration due to the Bragg peak and higher RBE. In treatment planning at HIMAC, the dose distribution is calculated based on dose measurements in water.

[Elucidation of the energy absorption spectra of the (11)C beam in a plastic scintillator.].

Heavy ion therapy using the energetic (12)C beam is successfully under way at HIMAC, Japan. The method is more advantageous than traditional radiation therapy in dose concentration owing to the Bragg peak and high relative biological effectiveness. A research study using the (11)C beam for heavy ion therapy in the future has been carried out in order to develop the capability of monitoring the dose distribution.