Neutron Activation Analysis Based on AB-BNCT Treatment Room.

Boron neutron capture therapy (BNCT) is an ideal binary targeted radiotherapy for treating refractory tumors. An accelerator-based BNCT (AB-BNCT) neutron source has attracted more and more attention due to its advantages such as higher neutron yield in the keV energy region, less gamma radiation, and higher safety. In addition to 10 B, neutrons also react with other elements in the treatment room during BNCT to produce many activation products.

[Study on the sensitivity of a volumetric modulated arc therapy plan verification equipment on multi-leaf collimator opening and closing errors and its gamma pass rate limit].

To investigate the pass rate limit of plan verification equipment for volumetric modulated arc therapy (VMAT) plan verification and its sensitivity on the opening and closing errors of multi-leaf collimator (MLC), 50 cases of nasopharyngeal carcinoma VMAT plan with clockwise and counterclockwise full arcs were randomly selected. Eight kinds of MLC opening and closing errors were introduced in 10 cases of them, and 80 plans with errors were generated. Firstly, the plan verification was conducted in the form of field-by-field measurement and true composite measurement.

Sensitivity of Three Patient-Specific Quality Assurance Systems to MLC Aperture Errors With Volumetric Modulated Arc Therapy.

To compare the sensitivity of ArcCHECK (AC), portal dosimetry (PD), and an in-house logfile-based system (LF) to multileaf collimators (MLC) aperture errors and the ability to identify these errors. For 12 retrospective original head and neck volumetric modulated arc therapy (VMAT) plans, MLC aperture errors of ± 0.4mm, ± 1.

An Inverse Dose Optimization Algorithm for Three-Dimensional Brachytherapy.

Purpose: To investigate an implementation method and the results of an inverse dose optimization algorithm, Gradient Based Planning Optimization (GBPO), for three-dimensional brachytherapy.

Methods: The GBPO used a quadratic objective function, and a dwell time modulation item was added to the objective function to restrict the dwell time variance. We retrospectively studied 4 cervical cancer patients using different applicators and 15 cervical cancer patients using the Fletcher applicator.

Radiotherapy dose distribution prediction for breast cancer using deformable image registration.

Background: Radiotherapy treatment planning dose prediction can be used to ensure plan quality and guide automatic plan. One of the dose prediction methods is incorporating historical treatment planning data into algorithms to estimate the dose-volume histogram (DVH) of organ for new patients. Although DVH is used extensively in treatment plan quality and radiotherapy prognosis evaluation, three-dimensional dose distribution can describe the radiation effects more explicitly.

COMPARISON OF BNCT DOSIMETRY CALCULATIONS USING DIFFERENT GEANT4 PHYSICS LISTS.

A comparison of Geant4 physics lists is conducted in the calculation of the total absorbed dose, boron dose, and non-boron dose in phantom, and the total depth-dose, boron depth-dose, and non-boron depth-dose along the beam axis for neutrons in a range of 0.0253 eV to 10 MeV. Physics processes are included for neutrons, photons, and charged particles, and calculations are conducted for neutrons and secondary particles.

An automated dose verification software for brachytherapy.

Purpose: To report an implementation method and the results of independent brachytherapy dose verification software (DVS).

Material And Methods: The DVS was developed based on Visual C++ and adopted a modular structure design. The DICOM RT files exported from a treatment planning system (TPS) were automatically loaded into the DVS.

Dosimetric study of GZP6 Co high dose rate brachytherapy source.

The purpose of this study was to obtain dosimetric parameters of GZP6 Co brachytherapy source number 3. The Geant4 MC code has been used to obtain the dose rate distribution following the American Association of Physicists in Medicine (AAPM) TG-43U1 dosimetric formalism. In the simulation, the source was centered in a 50 cm radius water phantom.

Monte Carlo dosimetric parameter study of a new (32)P brachytherapy source.

Objective: Recently, a new catheter-based (32)P brachytherapy source has been developed (College of Chemistry, Sichuan University) for use in high-dose-rate afterloader. This study presents the results of the dosimetric data of the Geant4 Monte Carlo (MC) simulation toolkit for this new (32)P brachytherapy source.

Methods: The new (32)P source had dimensions of 0.

Monte Carlo dosimetry of a new (90)Y brachytherapy source.

Purpose: In this study, we attempted to obtain full dosimetric data for a new (90)Y brachytherapy source developed by the College of Chemistry (Sichuan University) for use in high-dose-rate after-loading systems.

Material And Methods: The dosimetric data for this new source were used as required by the dose calculation formalisms proposed by the AAPM Task Group 60 and Task Group 149. The active core length of the new (90)Y source was increased to 4.

A semi-analytical model for calculating the penetration depth of a high energy electron beam in a water phantom with a magnetic field.

Purpose: As an electron beam is incident on a uniform water phantom in the presence of a lateral magnetic field, the depth-dose distribution of the electron beam changes significantly and forms the well-known 'Bragg peak', with a depth-dose distribution similar to that of heavy ions. This phenomenon has pioneered a new field in the clinical application of electron beams. For such clinical applications, evaluating the penetration depth of electron beams quickly and accurately is the critical problem.

[A fitted formula for calculating electron beams mean energy in the homogeneous water phantom].

The hybrid pencil beam model (HPBM) is an effective algorithm for calculating electron dose distribution in radiotherapy. The mean energy distribution of incident electron beam in phantom is one of the factors that affect the calculation accuracy of HPBM, especially in field edge areas near the end of the electron range. A new fitted formula based on Monte Carlo (MC) simulation data for electron beams with energy range of 6-20 MeV in the homogeneous water phantom is proposed in this paper.

[Fast gamma index calculation method in dose distribution comparison].

As a method of dosimetric verification in radiotherapy, gamma index has been widely used for evaluating dose distribution in research and clinical cases. However, for three-dimensional dose distributions, gamma index calculation is very time consuming for the computers. In this paper, based on a pre-sorting technique, we implement a parallel computing algorithm of gamma index on graphic processing unit (GPU).

[The specification of parameters driven by measurement data in the construction of virtual sources in Monte Carlo simulation].

Dose calculation algorithms based on the Monte Carlo (MC) method are widely regarded as the most accurate tool available in radiotherapy. The MC simulation in radiotherapy has been split into two parts, the radiation source simulation and patient simulation. In this research, a virtual source for simulating the linear accelerator head was constructed with measurement-driven models.

Three-dimensional electron dose calculation using an improved hybrid pencil beam model.

An improved hybrid-pencil beam model (HPBM) for electron-beam three-dimensional dose calculation has been studied. The model is based on the fact that away from the edges of a large field, the electron distribution function exactly equals that for an infinitely wide electron beam. In the present model, we use the bipartition model to calculate the longitudinal part of the pencil-beam distribution function, and Fermi-Eyges multiple-scattering theory to calculate its transverse part.