BACKGROUND: Ultra-high-dose-rate (UHDR) electron beams have been commonly utilized in FLASH studies and the translation of FLASH Radiotherapy (RT) to the clinic. The EDGE diode detector has potential use for UHDR dosimetry albeit with a beam energy dependency observed.
OBJECTIVE: The purpose is to present the electron beam response for an EDGE detector in dependence on beam energy, to characterize the EDGE detector\'s response under UHDR conditions, and to validate correction factors derived from the first detailed Monte Carlo model of the EDGE diode against measurements, particularly under UHDR conditions.
METHODS: Percentage depth doses (PDDs) for the UHDR Mobetron were measured with both EDGE detectors and films. A detailed Monte Carlo (MC) model of the EDGE detector has been configured according to the blueprint provided by the manufacturer under an NDA agreement. Water/silicon dose ratios of EDGE detector for a series of mono-energetic electron beams have been calculated. The dependence of the water/silicon dose ratio on depth for a FLASH relevant electron beam was also studied. An analytical approach for the correction of PDD measured with EDGE detectors was established.
RESULTS: Water/silicon dose ratio decreased with decreasing electron beam energy. For the Mobetron 9 MeV UHDR electron beam, the ratio decreased from 1.09 to 1.03 in the build-up region, maintained in range of 0.98-1.02 at the fall-off region and raised to a plateau in value of 1.08 at the tail. By applying the corrections, good agreement between the PDDs measured by the EDGE detector and those measured with film was achieved.
CONCLUSIONS: Electron beam response of an UHDR capable EDGE detector was derived from first principles utilizing a sophisticated MC model. An analytical approach was validated for the PDDs of UHDR electron beams. The results demonstrated the capability of EDGE detector in measuring PDDs of UHDR electron beams.

In the calibration procedure of area gamma dosemeters, how to accurately evaluate and correct the scattering contribution from the complex environmental factors to the point of test is the key problem to ensure the calibration accuracy. This paper proposed a fast correction method of the scattering contributions in the area gamma dosemeter calibration field. First, Monte Carlo method is employed to simulate the influence of scattering caused by different environmental factors in the calibration field, which is named as semi-panoramic reference radiation field. Then, a prediction model of the relationship between environmental factors and environmental scattering contribution is constructed based on the simulation data through the least squares support vector machine. With the model, the scattering contribution from the environmental factors can be fast estimated to correct the calibration results of the area gamma dosemeters, which will improve the accuracy of the calibration.

UNASSIGNED: It seems that dose rate (DR) and photon beam energy (PBE) may influence the sensitivity and response of polymer gel dosimeters. In the current project, the sensitivity and response dependence of optimized PASSAG gel dosimeter (OPGD) on DR and PBE were assessed.
UNASSIGNED: We fabricated the OPGD and the gel samples were irradiated with various DRs and PBEs. Then, the sensitivity and response (R2) of OPGD were obtained by MRI at various doses and post-irradiation times.
UNASSIGNED: Our analysis showed that the sensitivity and response of OPGD are not affected by the evaluated DRs and PBEs. It was also found that the dose resolution values of OPGD ranged from 9 to 33 cGy and 12 to 34 cGy for the evaluated DRs and PBEs, respectively. Additionally, the data demonstrated that the sensitivity and response dependence of OPGD on DR and PBE do not vary over various times after the irradiation.
UNASSIGNED: The findings of this research project revealed that the sensitivity and response dependence of OPGD are independent of DR and PBE.

The knowledge of the space radiation environment in spacecraft transition and in Mars vicinity is of importance for the preparation of the human exploration of Mars. ExoMars Trace Gas Orbiter (TGO) was launched on March 14, 2016 and was inserted into circular Mars science orbit (MSO) with a 400 km altitude in March 2018. The Liulin-MO dosimeter is a module of the Fine Resolution Epithermal Neutron Detector (FREND) aboard ExoMars TGO and has been measuring the radiation environment during the TGO interplanetary travel to Mars and continues to do so in the TGO MSO. One of the scientific objectives of the Liulin-MO investigations is to provide data for verification and benchmarking of the Mars radiation environment models. In this work we present results of comparisons of the flux measured by the Liulin-MO in TGO Mars orbit with calculated estimations. Described is the methodology for estimation the particle flux in Liulin-MO detectors in MSO, which includes modeling the albedo spectra and procedure for calculation the fluxes, recorded by Liulin-MO on the basis of the detectors shielding model. The galactic cosmic rays (GCR) and Mars albedo radiation contribution to the detectors count rate was taken into account. The GCR particle flux was calculated using the Badhwar O\'Neil 2014 model for December 1, 2018. Detailed calculations of the albedo spectra of protons, helium ions, neutrons and gamma rays at 70 km height, performed with Atmospheric Radiation Interaction Simulator (AtRIS), were used for deriving the albedo radiation fluxes at the TGO altitude. In particular, the sensitivity of the Liulin-MO semiconductor detectors to neutron and gamma radiation has been considered in order to calculate the contribution of the neutral particles to the detected flux. The results from the calculations suggest that the contribution of albedo radiation can be about 5% of the measured total flux from GCR and albedo at the TGO altitude. The critical effect of TGO orientation, causing different shading of the GCR flux by Mars, is also analysed in detail. The comparison between the measurements and estimations shows that the measured fluxes exceed the calculated values by at least 20% and that the effect of TGO orientation change is approximately the same for the calculated and measured fluxes. Accounting for the ACR contribution, secondary radiation and the gradient of GCR spectrum from 1 AU to 1.5 AU, the calculated flux may increase to match the measurement results. The results can serve for the benchmarking of GCRs models at Martian orbit.

The objective of this investigation is to assess the impact of supplementary lead curtains on the reduction of radiation dose exposure to operators during coronary interventional procedures. Seven standard positions during coronary angiography (foot, right foot, head, left foot, left lateral, left head, and right lateral) were simulated on a standard anthropomorphic phantom with radial artery access. Measurements were taken at two different heights, 125 cm and 155 cm, and dosimeters were used to measured surface incident dose rates for the first and second operators, both with and without additional lead curtains at various positions. Each position was measured 20 times, and arithmetic means were computed. At-test was utilised to compare dose rates with and without supplementary lead curtains, as well as dose rates with additional lead curtains at varying heights. The finding indicate that the dose rates of the first operator with supplementary lead curtains were not significantly lower compared to those without, except for the 125 cm head and left foot positions and the 155 cm head position with the additional lead curtain edge 10 cm below the umbilical level (tumbilical= 0.9, 0.4, 0.5,P> 0.05). The dose rates of the second operator with additional lead curtains were significantly lower than those without, with statistically significant differences (P< 0.05). The arithmetic mean dose rates for the first and second operators at each position were lowest when the upper edge of the additional lead curtain was situated 10 cm above the umbilical level. Employing supplementary lead curtains during coronary interventions effectively reduces radiation doses received by operators. The protective effect is enhanced when the additional lead curtain is closer to the irradiation field. Hence, it is recommended that additional curtains be employed judiciously, while ensuring that clinical procedures are not impeded, in order to effectively mitigate the radiation exposure of operators.

This study aimed to investigate the feasibility of applying 3D gel dosimeters for proton therapy. Two different formulations (5-5-3-5, 5-3-3-10) for the N-Isopropyl Acrylamide (NIPAM) polymer gel were used to find the best composition for the application of NIPAM polymer gels for proton therapy. The reaction of the gel under different physical conditions, including dependence on energy and dependence on the dose rate of the NIPAM gel under proton irradiation, was also explored. A NIPAM gel dosimeter was used to record the 3D dose distribution, and a self-developed parallel beam optical computed tomography scanner was used to obtain non-irradiated and post-irradiated gel phantom images. The NIPAM gel was filled into a cylindrical acrylic phantom. The results showed that the optical density of the irradiated NIPAM dosimeter was linear in the dose range of 0 to 6 Gy, and the linearity of the two NIPAM gel formulations at the depth of the dose point (2 cm) was 0.98 to 0.89. The dose depth curves showed different patterns with different gel sensitivities. This study demonstrated that the NIPAM gel dosimeter with the 5-3-3-10 formulation is suitable for verifying the dosimetry dose of proton beams.

Several physical factors such as photon beam energy, electron beam energy, and dose rate may affect the dosimetric properties of polymer gel dosimeters. The photon beam energy and dose rate dependence of PASSAG gel dosimeter were previously evaluated.
This study aims to assess the dosimetric properties of the optimized PASSAG gel samples in various electron beam energies.
The optimized PASSAG gel samples are first fabricated and irradiated to various electron energies (5, 7, 10 and 12 MeV). Then, the response (R2) and sensitivity of gel samples are analyzed by magnetic resonance imaging technique at a dose range of 0 to 10 Gy, scanning room temperature range of 15 to 22 °C, and post-irradiation time range of 1 to 30 days.
The R2-dose response and sensitivity of gel samples do not change under the evaluated electron beam energies (the differences are less than 5%). Furthermore, a dose resolution range of 11 to 38 cGy is obtained for the gel samples irradiated to different electron beam energies. Moreover, the findings show that the R2-dose response and sensitivity dependence of gel samples on electron beam energy varies over different scanning room temperatures and post-irradiation times.
The dosimetric assessment of the optimized PASSAG gel samples provides the promising data for this dosimeter during electron beam radiotherapy.

This study was to determine the significance of factors considered for the measurement accuracy of personal dosimeter in dosimetry services such as dosimetry service, irradiation category, years of use and readout frequency. The investigation included management information questionnaire, on-site visit and blind test. The blind test with random selected personal badge was used in inter-comparison of eight dosimetry services, and the test results followed ANSI/HPS N13.11 criteria. This study also analyzed the measurement deviations if they felt in the criteria of ICRP 75 or not. One-way ANOVA tests were used to analyze the significant difference of the measurement deviations in different dosimetry services, irradiation categories, and years of use. Simple linear-regression test was performed for the significance of the prediction model between measurement deviations and readout frequencies. All visited dosimetry services followed the proper statue of basic management and passed the performance check of the tolerance level. The average deviations corresponding to category I, category II deep dose, and category II shallow dose were 6.08%, 9.49%, and 10.41% respectively. There had significant differences of measurement deviation in different dosimetry services (p < 0.0001) and irradiation categories (p = 0.016) but no significant difference in years of use (p = 0.498). There was no significance in the linear-regression model between measurement deviation and badge readout frequencies. Based on the regular calibration of the personal dosimeter, the deviation of the measured value is mainly affected by different dosimetry services and irradiation categories; and there shows no significant influence by years of use and readout frequency.

To evaluate the measurement method of passive dosemeters for terrestrial gamma radiation measurements. An inter-comparison of passive dosemeters for terrestrial gamma radiation measurements was organized alternately by the Japan Chemical Analysis Center, National Institute for Radiological Protection of Chinese Center for Disease Control and Prevention and Radiation Monitoring Technical Center of Ministry of Environmental Protection every 2 years. The procedures and exposure conditions of the field-exposure and reference irradiation test were provided by the organizer. During 2019-2020, the En values of Field-1 and Field-2 in three laboratories were lower than 1.0 and assigned \'acceptable\' according to inter-comparison criteria. After the correction of the fading effect of dosemeter material, the En values of reference irradiation test (0.301 mGy, 1.000 mGy) in three laboratories were lower than 1.0 and assigned \'acceptable\'.

Optical fibers are being widely utilized as radiation sensors and dosimeters. Benefiting from the rapidly growing optical fiber manufacturing and material engineering, advanced optical fibers have evolved significantly by using functional structures and materials, promoting their detection accuracy and usage scenarios as radiation sensors. This paper summarizes the current development of optical fiber-based radiation sensors. The sensing principles of both extrinsic and intrinsic optical fiber radiation sensors, including radiation-induced attenuation (RIA), radiation-induced luminescence (RIL), and fiber grating wavelength shifting (RI-GWS), were analyzed. The relevant advanced fiber materials and structures, including silica glass, doped silica glasses, polymers, fluorescent and scintillator materials, were also categorized and summarized based on their characteristics. The fabrication methods of intrinsic all-fiber radiation sensors were introduced, as well. Moreover, the applicable scenarios from medical dosimetry to industrial environmental monitoring were discussed. In the end, both challenges and perspectives of fiber-based radiation sensors and fiber-shaped radiation dosimeters were presented.