A Retrospective Study of Patients Undergoing Palliative Radiotherapy for Airway Obstruction due to Lung Cancer.

Background/aim: In advanced stage lung cancer, bulky tumors can cause serious symptoms such as malignant airway obstruction (MAO). Prompt response to airway obstruction might be essential to improve quality of life and prolong life expectancy. Palliative external beam radiotherapy (EBRT) is a less invasive and highly safe treatment method that can alleviate symptoms and at the same time treat lung cancer.

VMAT Planning With Xe-CT Functional Images Enables Radiotherapy Planning With Consideration of Lung Function.

Background/aim: The most severe adverse event of radiotherapy in lung cancer is radiation pneumonitis (RP). Some indices commonly used to prevent RP are evaluated based on the anatomical lung volume. The irradiation dose may be more accurately assessed by using functional lung volume.

Evaluation of robustness in hybrid intensity-modulated radiation therapy plans generated by commercial software for automated breast planning.

This study aimed to evaluate the robustness against geometric uncertainties in the hybrid intensity-modulated radiation therapy (IMRT) plans generated by commercially available software for automated breast planning (ABP). The ABP plans were compared with commonly used forward-planned field-in-field (FIF) technique plans. The planning computed tomography datasets of 20 patients who received left-sided breast-conserving surgery were used for both the ABP and FIF plans.

Evaluation of prediction and classification performances in different machine learning models for patient-specific quality assurance of head-and-neck VMAT plans.

Purpose: The purpose of this study is to evaluate the prediction and classification performances of the gamma passing rate (GPR) for different machine learning models and to select the best model for achieving machine learning-based patient-specific quality assurance (PSQA).

Methods: The measurement verification of 356 head-and-neck volumetric modulated arc therapy plans was performed using a diode array phantom (Delta4 Phantom), and GPR values at 2%/2 mm with global normalization and 3%/2 mm with local normalization were calculated. Machine learning models, including ridge regression (RIDGE), random forest (RF), support vector regression (SVR), and stacked generalization (STACKING), were used to predict the GPR.

Variation of Tumor Volume During Moderate Hypo-Fractionated Stereotactic Body Radiation Therapy for Lung Cancer.

Aim To investigate the variation of tumor volume during moderate hypo-fractionated stereotactic body radiation therapy (SBRT). Patients and Methods Twenty patients, who received SBRT at our institution, were included in the analysis. A prescribed dose was 56 Gy at iso-center in seven fractions.

[Feasibility Study for the Development of an Application for Simulated Virtual Reality Radiation Therapy Experiences Using Android and iOS Devices].

Using virtual reality (VR) technology such as head-mounted displays, users can be immersed in a virtual world and perceive it as reality. In radiation therapy departments, pretreatment patients and students rarely observe treatment rooms and treatment devices, making it difficult to understand the overall flow of radiation therapy. In this study, to facilitate the understanding and teaching of radiation therapy, we suggest the implementation of VR technology and develop software compatible with VR to enable a pertinent comprehension of radiation therapy.

Evaluation of geometrical uncertainties on localized prostate radiotherapy of patients with bilateral metallic hip prostheses using 3D-CRT, IMRT and VMAT: A planning study.

Objective: Since most radiation treatment plans are based on computed tomography (CT) images, which makes it difficult to define the targeted tumor volume located near a metal implant, this study aims to evaluate and compare three treatment plans in order to optimally reduce geometrical uncertainty in external radiation treatment of localized prostate cancer.

Methods: Experimental subjects were three prostate patients with bilateral hip prosthesis who had undergone radical radiotherapy. The treatment plans were five-field three-dimensional conformal radiation therapy (3D-CRT), fixed 5-field intensity-modulated radiation therapy (IMRT) using similar gantry angles, and single-arc volumetric modulated arc therapy (VMAT).

Evaluation of a new commercial automated planning software for tangential breast intensity-modulated radiation therapy.

Automated treatment planning may decrease the effort required in planning and promote increased routine clinical use of intensity-modulated radiation therapy (IMRT) for many breast cancer patients. The aim of this study was to evaluate a new commercial automated planning software for tangential breast IMRT by comparing it with clinical plans from whole-breast irradiation. We prospectively enrolled 150 patients with Stage 0-1 breast cancer who underwent breast-conserving surgery at our institution between September 2016 and August 2017.

Commissioning of the Mobius3D independent dose verification system for TomoTherapy.

In radiation therapy, a secondary independent dose verification is an important component of a quality control system. Mobius3D calculates three-dimensional (3D) patient dose using reference beam data and a collapsed cone convolution algorithm and analyzes dose-volume histogram automatically. There are currently no published data on commissioning and determining tolerance levels of Mobius3D for TomoTherapy.

Retrospective analysis of multi-institutional, patient-specific treatment planning results of high-dose-rate intracavitary brachytherapy for gynecological cancer using V.

The objective of this study was to clarify the usefuleness of the K parameters of the independent verification method using V (the volume of water receiving 100% of the prescription dose) for institutions implementing the high-dose-rate (HDR) intracavitary brachytherapy for gynecological cancer. The data of 249 plans of 11 institutions in Japan were used, and the constant K value obtained by a parameter fit for single-Ir, two-Ir, and three-Ir systems was calculated. The predicted total dwell time calculated using the constant K value was defined as T, and the total dwell time calculated using a radiation treatment planning system was defined as T.

Simple index for validity of the evaluation point for dosimetric verification results of intensity-modulated radiation therapy using a Farmer-type ionization chamber.

Purpose: Based on a retrospective analysis, this study aims to develop a simple index for validity of the evaluation point for the dosimetric verification of intensity-modulated radiation therapy (IMRT).

Methods: The results for the dosimetric verifications of a total of 69 IMRT plans were analyzed in this study. A Farmer-type ion chamber was used as a dose detector, and a solid water-equivalent phantom was used.

Application of a radiophotoluminescent glass dosimeter to nonreference condition dosimetry in the postal dose audit system.

Purpose: The purpose of this study was to obtain a set of correction factors of the radiophotoluminescent glass dosimeter (RGD) output for field size changes and wedge insertions.

Methods: Several linear accelerators were used for irradiation of the RGDs. The field sizes were changed from 5 × 5 cm to 25 × 25 cm for 4, 6, 10, and 15 MV x-ray beams.

Guidelines for respiratory motion management in radiation therapy.

Respiratory motion management (RMM) systems in external and stereotactic radiotherapies have been developed in the past two decades. Japanese medical service fee regulations introduced reimbursement for RMM from April 2012. Based on thorough discussions among the four academic societies concerned, these Guidelines have been developed to enable staff (radiation oncologists, radiological technologists, medical physicists, radiotherapy quality managers, radiation oncology nurses, and others) to apply RMM to radiation therapy for tumors subject to respiratory motion, safely and appropriately.

[Field Survey Results on Output for X-ray Therapeutic Accelerators in Radiotherapy Institutions of Saitama and Tochigi Prefectures.].

Field survey on output for X-ray therapeutic accelerators took place three times in Saitama Prefecture. The result of the field survey in 1997 showed the different rate from the designated dose at peak depth of 35 beams in 18 institutions. As different rate within +/-5% stood 91.

Feasibility study of glass dosimeter postal dosimetry audit of high-energy radiotherapy photon beams.

Introduction: The characteristics of a glass dosimeter were investigated for its potential use as a tool for postal dose audits. Reproducibility, energy dependence, field size and depth dependence were compared to those of a thermoluminescence dosimeter (TLD), which has been the major tool for postal dose audits worldwide.

Materials And Methods: A glass dosimeter, GD-302M (Asahi Techno Glass Co.

Cross-calibration of ionization chambers in proton and carbon beams.

The calibration coefficients of a parallel plate ionization chamber are examined by comparing the coefficients obtained through three methods: a calculation from a 60Co calibration coefficient, N(D, omega, 60Co), a cross-calibration of a parallel plate ionization chamber using a cylindrical ionization chamber at the plateau region of a mono-energetic beam and a cross-calibration of the chamber using a cylindrical chamber at the middle of the SOBP of the therapeutic beams. This paper also examines reference conditions for determining absorbed dose to water in the cases of therapeutic carbon and proton beams. In the dose calibration procedure recommended by IAEA, irradiation fields should be larger than 10 cm in diameter and the water phantom should extend by at least 5 cm beyond each side of the field.

Reconstruction of biologically equivalent dose distribution on CT-image from measured physical dose distribution of therapeutic beam in water phantom.

From the standpoint of quality assurance in radiotherapy, it is very important to compare the dose distributions realized by an irradiation system with the distribution planned by a treatment planning system. To compare the two dose distributions, it is necessary to convert the dose distributions on CT images to distributions in a water phantom or convert the measured dose distributions to distributions on CT images. Especially in heavy-ion radiotherapy, it is reasonable to show the biologically equivalent dose distribution on the CT images.