Automated Workflow for Calculating the Collective and Average Effective Doses of Galactic Cosmic Radiation Received by Pilots in Taiwan from 2006 to 2021.

ABSTRACT: On the basis of statistical data obtained from publicly available annual civil aviation reports, we developed an automated workflow for estimating the overall radiation exposure of aircraft pilots caused by galactic cosmic radiation. The workflow comprises several data-processing scripts that work with the batch analysis capability built in the NTHU Flight Dose Calculator . This method can quickly provide best possible estimates of the annual collective and average effective doses received by pilots of various airlines because all passenger, cargo, and charter flights operated that year were considered rather than some selected flights. The workflow and its implementation as well as analysis of results for the period of 2006-2021 are discussed herein. The results revealed that in 2019, six airlines in Taiwan operated 479 separate flight segments with 226 aircraft. The collective effective dose received by all 2,986 pilots was approximately 5,536 person-mSv; hence, the average individual effective dose was 1.85 mSv. During the COVID-19 pandemic, the doses decreased by more than half. In 2020, the collective effective dose received by all 2,936 pilots decreased sharply to 2,527 person-mSv, corresponding to an average effective dose per pilot of only 0.86 mSv. During 2006-2019, the annual average effective dose per pilot in Taiwan was between 1.65 and 2.71 mSv, and the average effective dose rate per flight hour was 3.15 µSv h. -1.

Simulation of cosmic rays inside an aircraft: spectral perturbation and dose reduction due to aircraft structures and contents.

In this study, an intricate combinatorial geometry model of a Boeing 777-300ER aircraft was constructed for Monte Carlo transport simulations. The aircraft-induced perturbations of the energy spectra and effective doses of secondary cosmic rays at a typical civil aviation altitude (10 km) were investigated on a component-by-component basis, which included neutrons, protons, photons, electrons, positrons, muons and charged pions. Two geomagnetic cutoff rigidities (1.35 and 15.53 GV) and two solar modulation parameters (430 and 1360 MV) were considered in the aforementioned simulations. The characteristics of various cosmic-ray components at six locations along the fuselage were assessed and compared with those of an unperturbed radiation field in the atmosphere. Aircraft structures and contents reduced the effective doses of personnel inside the aircraft to varying degrees, up to an ~32% reduction in the middle section of the passenger cabin. On average, the dose reduction was ~12-16% depending on geomagnetic and solar conditions. Quantifying the aircraft's self-shielding effects can further improve the estimation accuracy of aircrew and passengers' exposure to cosmic radiation. Information regarding the perturbed energy spectra of cosmic rays may be useful for designing onboard experiments or analyzing onboard measurement data.

NeuTHOR Station-A Novel Integrated Platform for Monitoring BNCT Clinical Treatment, Animal and Cell Irradiation Study at THOR.

(1) Background: A well-established Boron Neutron Capture Therapy (BNCT) facility includes many essential systems, which are the epithermal neutron beam system, on-line monitoring system (OMS), QA/QC (quality assurance or quality control) system, boron concentration (BC) measurement system, and treatment planning system (TPS). Accurate data transmission, monitoring, and deposition among these systems are of vital importance before, during, and after clinical, animal, and cell BNCT irradiation. This work developed a novel integrated platform NeuTHOR Station (NeuTHORS) for BNCT at Tsing Hua Open-pool Reactor (THOR). Apart from the data of the OMS and QA/QC system, the data of BC and TPS can be loaded on NeuTHORS before BNCT clinical, animal, and cell irradiation. (2) Methods: A multi-paradigm computer programming language c# (c sharp) was used to develop the integrated platform NeuTHORS. The design of NeuTHORS is based on the standard procedures of BNCT treatment or experiment at THOR. Moreover, parallel testing with OMS-BNCT (the former OMS) and QA/QC of THOR was also performed for more than 70 times to verify the validation of NeuTHORS. (3) Results: According to the comparisons of the output, NeuTHORS and OMS-BNCT and QA/QC of THOR show very good consistency. NeuTHORS is now installed on an industrial PC (IPC) and successfully performs the monitoring of BNCT Treatment at THOR. Patients' f BC and TPS data are also input into NeuTHORS and stored on IPC through an internal network from BC measurement room and TPS physicist. Therefore, the treatment data of each patient can be instantaneously established after each BNCT treatment for further study on BNCT. NeuTHORS can also be applied on data acquisition for a BNCT-related study, especially for animal or cell irradiation experiments. (4) Conclusions: A novel integrated platform NeuTHOR Station for monitoring BNCT clinical treatment and animal and cell irradiation study has been successfully established at THOR. With this platform, BNCT radiobiology investigations will be efficiently performed and a thorough data storage and analysis system of BNCT treatments or experiments can thus be systematically built up for the further investigation of BNCT at THOR.

Comparison of different methods for the shielding analysis of an AB-BNCT facility based on the Be(p,xn) reaction with 30-MeV protons.

Five shielding calculation methods were employed to estimate the dose rate distribution around an accelerator-based boron neutron capture therapy facility. Their performances were compared in terms of accuracy and efficiency. The results indicate that the hybrid deterministic/Monte Carlo method is the most efficient in the context of accurate modeling and simulation, whereas the analytical approximation with pre-generated source terms and attenuation lengths is preferable in the design phase because of its simplicity and ease of verification while retaining a reasonable accuracy.

The overview and prospects of BNCT facility at Tsing Hua Open-pool reactor.

The whole picture of the BNCT facility at Tsing Hua Open-pool Reactor will be presented which consists of the following aspects: the construction project, the beam quality, routine operations including the QA program for the beam delivery, determination of boron-10 concentration in blood, T/N ratio, and the clinical affairs including the patient recruit procedure and the patient irradiation procedure. The facility is positioned to serve for conducting clinical trials, emergent (compassionate) treatments, and R&D works.

Dose estimation of animal experiments at the THOR BNCT beam by NCTPlan and Xplan.

Dose estimation of animal experiments affects many subsequent derived quantities, such as RBE and CBE values. It is important to ensure the trustiness of calculated dose of the irradiated animals. However, the dose estimation was normally calculated using simplified geometries and tissue compositions, which led to rough results. This paper introduces the use of treatment planning systems NCTplan and Xplan for the dose estimation. A mouse was taken as an example and it was brought to hospital for micro-PET/CT scan. It was found that the critical organ doses of an irradiated mouse calculated by simplified model were unreliable in comparison to Xplan voxel model. The difference could reach the extent of several tenths percent. It is recommended that a treatment planning system should be introduced to future animal experiments to upgrade the data quality.

Performance evaluation of the source description of the THOR BNCT epithermal neutron beam.

This paper aims to evaluate the performance of the source description of the THOR BNCT beam via different measurement techniques in different phantoms. The measurement included (1) the absolute reaction rate measurement of a set of triple activation foils, (2) the neutron and gamma-ray dose rates measured using the paired ionization chamber method, and (3) the relative reaction rate distributions obtained using the indirect neutron radiography. Three source descriptions, THOR-Y09, surface source file RSSA, and THOR-50C, were tested. The comparison results concluded that THOR-Y09 is a well-tested source description not only for neutron components, but also for gamma-ray component.