Publications by authors named "Hirotaki Kouta"
Background/aim: This study aimed to predict the optimal timing for adaptive radiation therapy (ART) using two-dimensional X-ray image-based water equivalent thickness (2DWET).
Patients And Methods: Forty patients with oropharyngeal and hypopharyngeal cancer underwent Computed Tomography (CT) rescanning during treatment. An adaptive score (AS) was proposed to guide ART decisions based on changes in four dose indices: target coverage, spinal cord dose, parotid gland dose, and over-dose volume.
Article Synopsis
- - The study evaluated the effectiveness of using anterior oblique portals (AOP) in radiotherapy for early-stage glottic cancer, aiming to minimize radiation exposure to critical areas like the internal carotid arteries and pharyngeal constrictor muscle.
- - Out of 66 patients treated with radiotherapy, nearly half received AOP, and results showed no significant difference in local failure or survival rates between AOP and standard treatments, but AOP significantly reduced the incidence of severe acute mucositis.
- - The findings suggest that AOP maintains effective radiation dose coverage to the cancer while reducing harmful exposure to important surrounding structures.
Background: Volumetric modulated arc therapy (VMAT) for locally advanced rectal cancer (LARC) has emerged as a promising technique, but the planning process can be time-consuming and dependent on planner expertise. We aimed to develop a fully automated VMAT planning program for LARC and evaluate its feasibility and efficiency.
Methods: A total of 26 LARC patients who received VMAT treatment and the computed tomography (CT) scans were included in this study.
Background/aim: This study pursued two goals: Firstly, to search for anatomical structures strongly correlating with dose deterioration, and secondly to investigate the effectiveness of image registration focusing on critical anatomy by comparing it with a conventional method. The aim was to achieve robust image registration to correct for anatomical changes during treatment.
Patients And Methods: Twenty patients with head and neck cancer were enrolled, and 68 simulation computed tomography (CT) and rescan CT image sets were retrospectively analyzed.
Purpose: We propose a method that potentially improves the outcome of mutual-information-based automatic image registration by using the contrast enhancement filter (CEF).
Methods: Seventy-six pairs of two-dimensional X-ray images and digitally reconstructed radiographs for 20 head and neck and nine lung cancer patients were analyzed retrospectively. Automatic image registration was performed using the mutual-information-based algorithm in VeriSuite®.
Article Synopsis
- Researchers developed a system using 2D x-ray images to detect anatomical changes in patients with head and neck cancer, analyzing images from the initial treatment and subsequent days.
- The system converted x-ray images to water equivalent thickness (WET) to quantify changes and compared these with differences measured on CBCT images, using lateral neck distance (ΔLND) as a reference.
- Results showed a close correlation between WET changes and LND, with high sensitivity (>85%) in detecting anatomical changes, demonstrating the system's reliability for monitoring treatment effects.
Aim: The primary objective was to assess set-up errors (SE) and secondary objective was to determine optimal safety margin (SM).
Background: To evaluate the SE and its impact on the SM utilizing electronic portal imaging (EPI) for pelvic conformal radiotherapy.
Material And Methods: 20 cervical cancer patients were enrolled in this prospective study.