Development of shielding evaluation and management program for O-ring type linear accelerators.

The shielding parameters can vary depending on the geometrical structure of the linear accelerators (LINAC), treatment techniques, and beam energies. Recently, the introduction of O-ring type linear accelerators is increasing. The objective of this study is to evaluate the shielding parameters of new type of linac using a dedicated program developed by us named ORSE (O-ring type Radiation therapy equipment Shielding Evaluation).

Evaluating the performance of thermoplastic 3D bolus used in radiation therapy.

A 3D-printed bolus is being developed to deliver accurate doses to superficial cancers. In this study, flexible thermoplastic filaments, specifically PLA, TPU, PETG, and HIPS, were fabricated into boluses and then compared to commercial bolus for the variation of the dose elevation region of photon beams. The experimental results indicate that the maximum dose depth is similar, and the consistent trend of the percentage depth dose confirms the potential usage as a build-up bolus.

Comparison of skin dose in IMRT and VMAT with TrueBeam and Halcyon linear accelerator for whole breast irradiation.

With the increasing use of flattening filter free (FFF) beams, it is important to evaluate the impact on the skin dose and target coverage of breast cancer treatments. This study aimed to compare skin doses of treatments using FFF and flattening filter (FF) beams for breast cancer. The study established treatment plans for left breast of an anthropomorphic phantom using Halcyon's 6-MV FFF beam and TrueBeam's 6-MV FF beam.

Dosimetric verification of annual quality assurance for a linear accelerator using a transmission type detector.

The purpose of our study is to establish an efficient quality assurance (QA) procedure using a transmission-type detector (IBA, Stealth chamber), a reference signal detector, as a field chamber. Relative dosimetry items, including monitor unit linearity, output constancy based on dose rate and field size, and output factor were measured and compared with results obtained from the Farmer-type chamber (IBA, Wellhofer, FC65-G). Moreover, output for each field size was measured to assess its applicability to small fields.

Development of open access tool for automatic use factor calculation using DICOM-RT patient data.

Our study recalculated the use factor of linear accelerators (LINACs) by using an in-house program based on Digital Imaging and Communications in Medicine radiation therapy (DICOM-RT). We considered the impact of advancements and changes in treatment trends, including modality, technology, and radiation dose, on the use factor, which is one of the shielding parameters. In accordance with the methodology described in the NCRP 151 report, we computed the use factor for four linear accelerators (LINACs) across three hospitals.

Clinical Application of a Customized 3D-Printed Bolus in Radiation Therapy for Distal Extremities.

In radiation therapy (RT) for skin cancer, tissue-equivalent substances called boluses are widely used to ensure the delivery of an adequate dose to the skin surface and to provide a radioprotective effect for normal tissue. The aim of this study was to develop a new type of three-dimensional (3D) bolus for RT involving body parts with irregular geometries and to evaluate its clinical feasibility. Two 3D-printed boluses were designed for two patients with squamous cell carcinoma (SCC) of their distal extremities based on computed tomography (CT) images and printed with polylactic acid (PLA).

Clinical Application Study of Semi-cylindrical Beam Spoiler for Radiation Treatment of Early-stage Glottic Cancer Patients.

Background/aim: The purpose of this study was to determine whether a semi-cylindrical beam spoiler (sCBS) developed herein effectively increases the skin dose in patients with early-stage glottic cancer.

Patients And Methods: We measured the surface doses for 26 patients who used the sCBS during treatment of early-stage glottic cancer through a parallel-opposed lateral two-field 6 MV photon beam. Measurements were performed by attaching optically stimulated luminescent dosimeters to the left, right, anterior (in-field), inferior, and superior (out-field) sides of the patient.

Usefulness of Semi-cylindrical Beam Spoiler in Treatment of Early Glottic Cancer Using 6 MV Photon Beam.

Background/aim: To assess the dosimetric influence of a semi-cylindrical beam spoiler (sCBS) for the treatment of early glottic cancer using a 6 MV photon beam.

Patients And Methods: The 2D dose distributions were also calculated and measured with and without the sCBS and with a 0.5 cm thick bolus.