Dosimetry System Research Articles

Time-resolved dose measurements of linear accelerator pulses using a fibre optic sensor: Applications and challenges

We present time-resolved radioluminescence (RL) measurements from P-doped silica optical fibre, demonstrating potential utility in pulsed source dosimetry. When subjected to 140 MU/min from a 6 MV photon linac source, a 220 µm-core fibre has produced a RL response of 720 ± 20 photon counts/pulse from a saw-tooth ~ 40 µs duration return-to-baseline waveform. Conversely, the Cerenkov stem signal within the radiation insensitive carrier fibre is observed to offer an amplitude amounting to a little less than 3% of that of the P-doped fibre, the sharply spiked response being of ~ 2 µs duration. On the basis of these results, the practical applications and the challenges in the establishment of an effective dosimetry system are discussed.

Computational model of a 3D dosimetry system - ArcCHECK®

Ionizing radiation therapies have been improving over the years, becoming more specific for each patient. Thereby, as the treatment planning system (TPS) complexities increases, the quality assurance (QA) methods have to be in constant evolution. One of the techniques that demand great complexity is the Volumetric Modulated Arc Therapy (VMAT), and one possible way to VMAT commissioning is using 3D dosimetry systems. Recently a new 3D dosimetry system called ArcCHECK had been developed and commercialized mainly for VMAT quality assurance. It is water-equivalent and composed by an array of 1386 diodes arranged in a helical pattern. Since simulation methods, like Monte Carlo method, ensure highly accurate results, MCNP (A General Monte Carlo N-Particle Transport Code System) is totally reliable for problems that involve radiation transport. This work presents two computational models for Monte Carlo simulations to predict detection responses in the QA procedure using the ArcCHECK. The computational models were validated comparing the system responses obtained from MCNP6 simulations against measured responses due to a 6 MeV clinical photon beam from a Linear Accelerator. 2D dose maps were reported here with good agreement between simulated and measured values.

Dosimetric Impact of a New Computational Voxel Phantom Series for the Japanese Atomic Bomb Survivors: Children and Adults

One of the largest sources of data on radiation exposure in humans is the study of the atomic bomb survivors at Hiroshima and Nagasaki, Japan performed by the Radiation Effects Research Foundation (RERF). As part of their retrospective dosimetry efforts for the atomic bomb survivors, RERF published two core systems: Dosimetry System 1986 (DS86) and Dosimetry System 2002 (DS02). Due to computing limitations at the time, only three stylized phantoms (an infant, child and adult) were used in DS86 and DS02 to represent the entire Japanese population. In this study, we sought to evaluate the dosimetric differences that should be expected from using an updated and age-expanded phantom series with the survivor cohort. To this end, we developed a new series of hybrid phantoms, based on the Japanese population of 1945, which has greater anatomical realism and improved age resolution over those used by RERF. These phantoms were converted to voxel format and compared to their older counterparts through the calculation of organ dose coefficients using DS02 free-in-air particle fluences at three distances from the bomb hypocenter. From the photon portion of the spectra, organ dose differences of up to nearly 25% are expected between the old and new series, while organ dose differences of up to nearly 70% are expected from the neutron portion. We also compared organ dose coefficients among themselves to determine the accuracy in the use of one organ dose as the epidemiological surrogate to another. Certain organ-surrogate pairs were shown to be inappropriate, such as the use of colon dose for breast risk analyses. Overall, our new series of phantoms provides significant improvements to survivor organ dosimetry, especially to those survivors who were previously misrepresented in body size by their stylized phantom and to those who experienced a highly-directional irradiation field.

Dosimetric effectiveness in implants with distinct ho166-seed distributions in a prostate model

Currently, there is a need to produce new therapeutic techniques for the treatment of prostate tumors, considering the high incidence of the disease and significant morbidity rates associated with surgery and radiotherapy. Simulations in brachytherapy produce essential information about the efficiency and dosimetric efficacy compared to other techniques. This study estimated the efficiency of dosimetry by parameters of merit generated from volumetric distributions of absorbed doses simulating two spatial distributions of Ho-166 seeds in a prostate model. A computer voxel model was developed, using the SISCODES (Computational System for Dosimetry by Neutrons and Photons by Stochastic Methods applied to radiology and radiotherapy) code. The virtual model reproduced a cubic box, filled with muscle equivalent tissue (TE), in which a 5-cm diameter sphere with TE-prostate was positioned 2-cm from the air-interface. Two Ho-166 seed distributions were employed with distinct pitches: 9 and 10 mm, with same distance between seed of 8mm in a fillet (needle). The MCNP5 code generated the energy deposited per unit mass in each voxel .The spatial dose distributions were obtained for each of the seed distributions. The following parameters-of-merit were evaluated: maximum dose values and histograms. The parameters were compared between the two simulated groups. It was possible to evaluate the most appropriate distribution to the prostate brachytherapy, which has been shown to be a function of the injected seed activity.

An algorithmic approach to single-probe Cherenkov removal in pulsed x-ray beams.

The removal of Cherenkov light in an optical dosimetry system is an important process to ensure accurate dosimetry without compromising spatial resolution. Many solutions have been presented in the literature, each with advantages and disadvantages. We present a methodology to remove Cherenkov light from a scintillator fiber optic dosimeter in a pulsed megavoltage x-ray beam using the temporal waveform across the pulse. A sample waveform of Cherenkov light can be measured by exposing only the fiber to the beam. By assuming that the Cherenkov waveform closely matches the intensity of incident radiation, this waveform can be convoluted with the instantaneous scintillation response function to generate an expected scintillation signal. By finding the least-squares fit between these two functions and the experimental data, the estimated Cherenkov contribution can be subtracted off the net signal. This can be applied for arbitrarily complex Cherenkov waveforms (within the 2ns timing resolution of the data acquisition), and in fact, the results suggest more fluctuations in the waveforms provide a better fit to data. Four beam profiles for different field sizes and energies were found with this method. They closely matched references data measured with ionization chamber with average differences across the beam no more than 4%. Noisy waveforms are assumed to be the primary cause of differences between the analyzed scintillator and IC results. We propose methods for improving the results and optimizing the data acquisition and analysis processes. These results demonstrate that it is possible and effective with a single probe to use function fitting of expected data to experimental to remove a complicated Cherenkov signal from the net light signal in pulsed-beam optical dosimetry.

Dosimetric characterization of LiMgPO4:Tb,B phosphor for its application in food irradiation

Optically stimulated luminescence (OSL) intensity versus dose response of indigenously developed LiMgPO4:Tb,B (LMP) disks is linear in the range of 1 mGy–1 kGy. Currently, no other synthetic OSL phosphor is available, which covers such a large dose range. In order to assess the feasibility of using the phosphor in low-dose food irradiation dosimetry (up to 1 kGy), dosimetric characterization of LMP-based OSL dosimeter was carried out under both, gamma and electron beam irradiation. The doses estimated by LMP and routine dosimeters match well in the field trials. Hence, this phosphor has the potential to be used in phytosanitary application using radiation, where delivered doses are of the order of 0.01–1 kGy. Practical applications Food irradiation dosimetry, in India, is being carried out using chemical dosimeters such as Fricke, Ceric-cerous sulphate, and Alanine-electron paramagnetic resonance. The former two are liquid dosimeters kept in glass tubes and therefore need to be handled delicately during irradiation. The complex chemical preparation, sensitive to environmental conditions (temperature, humidity, etc.) and temperature changes, sensitive to UV radiation and the high sensitivity to impurities make these dosimetry systems inconvenient for routine applications. The OSL intensity versus dose response of indigenously developed LiMgPO4:Tb,B (LMP) has been observed to be linear up to 1 kGy. Apart from good dosimetric qualities, other qualities of the dosimeter system are quick readout, ease of handling, automated readout mechanisms, and integrity in harsh environments. The above-discussed attributes make LMP-based OSL dosimeter a potential candidate to carry out dosimetry during phytosanitary application of radiation in low-dose range (0.01–1 kGy). This range includes irradiation of mangoes, onions, potatoes, etc.

First operation of the SASE1 undulator system of the European X-ray Free-Electron Laser.

The European XFEL comprises three undulator systems. All of the systems use standardized mechanical, magnetic and control components. The key elements such as undulators, phase shifters and quadrupole movers as well as their controls are described, with special emphasis on the SASE1 undulator system, which was the first to become operational and has been lasing since May 2017. The role of these systems for the commissioning is outlined with special emphasis on beam-based alignment, which was important to achieve first lasing. Radiation damage was observed. The exposure doses were measured with the online radiation dosimetry system. Countermeasures and latest results are reported, which are important for a high-duty-cycle machine such as the European XFEL.

Radiation Monitoring System of the Novosibirsk FEL

The dosimetry system at the FEL facility registers the dose rates in workrooms and in the accelerator hall. The collected information is stored in the database, and the data is visualized in real time. The sensors installed in the accelerator hall are used for monitoring both radiation levels and beam losses on the walls of the vacuum chamber of the FEL’s transport tracks.

Exposure measurement error in air pollution studies: A framework for assessing shared, multiplicative measurement error in ensemble learning estimates of nitrogen oxides

BackgroundIncreasingly ensemble learning-based spatiotemporal models are being used to estimate residential air pollution exposures in epidemiological studies. While these machine learning models typically have improved performance, they suffer from exposure measurement error that is inherent in all models. Our objective is to develop a framework to formally assess shared, multiplicative measurement error (SMME) in our previously published three-stage, ensemble learning-based nitrogen oxides (NOx) model to identify its spatial and temporal patterns and predictors. MethodsBy treating the ensembles as an external dosimetry system, we quantified shared and unshared, multiplicative and additive (SUMA) measurement error components in our exposure model. We used generalized additive models (GAMs) with a smooth term for location to identify geographic locations with significantly elevated SMME and explain their spatial and temporal determinants. ResultsWe found evidence of significant shared and unshared multiplicative error (p < 0.0001) in our ensemble-learning based spatiotemporal NOx model predictions. Unshared multiplicative error was 26 times larger than SMME. We observed significant geographic (p < 0.0001) and temporal variation in SMME with the majority (43%) of predictions with elevated SMME occurring in the earliest time-period (1992–2000). Densely populated urban prediction regions with complex air pollution sources generally exhibited highest odds of elevated SMME. ConclusionsWe developed a novel statistical framework to formally evaluate the magnitude and drivers of SMME in ensemble learning-based exposure models. Our framework can be used to inform building future improved exposure models.

Validation of secondary dose calculation system with manufacturer-provided reference beam data using heterogeneous phantoms.

The Mobius3D (M3D) system (Mobius Medical Systems) is a second-check dosimetry system. We investigated the dose calculation accuracy of this system using heterogeneous phantoms with reference beam data provided by the manufacturer using simple and patient plans. We compared the dose distributions between M3D and the treatment planning system, as well as the measurements in solid water phantoms, heterogeneous phantoms, and patient plans for Varian and Elekta accelerators. The M3D results agreed well with the measurements in the solid water phantoms for the simple plans. However, the accuracy of M3D appeared to depend on the type of accelerator, as indicated by the slight differences in the dose measurements. Furthermore, the M3D dose measurements differed by 5-10% in the lung and bone regions. Regarding the patient plans, we confirmed that M3D is reasonably accurate as a second-check system, despite the slight accelerator type-dependent dose difference.

MWDS-2016: THE SLOW DISSOLUTION RATE FOR PLUTONIUM NITRATE INTAKES AT THE MAYAK FACILITY.

The slow dissolution rate of material deposited in the lung plays a key role in determining the eventual radiation dose received by the lung. It is therefore of great importance to establish a reliable value for this parameter, to incorporate into the latest Mayak Worker Dosimetry System (MWDS-2016). Disparate values have been obtained for the slow dissolution rate of plutonium nitrate. A volunteer study performed by Public Health England (PHE) and an analysis of United States Transuranium and Uranium Registries (USTUR) case 0269 have yielded slow dissolution rates in the region of 10-40 × 10-4 d-1. However, autopsies performed on 20 Mayak workers, exposed predominantly to nitrates, have resulted in estimates of slow dissolution rates of around 2.4 × 10-4 d-1. Three hypotheses have been proposed to explain this discrepancy: (1) a slower dissolution rate in the interstitium, (2) a third exponential component in the dissolution function and (3) a small component of oxide in the aerosol to which Mayak 'nitrate' workers were exposed. This paper describes tests of these competing hypotheses. Bayesian methods have been applied to the following datasets: PHE volunteer data; Beagle dog data; USTUR cases and Mayak worker data. It is concluded that a mixture of oxide and nitrate material, with the oxide forming ~14% of the intake, best describes the Mayak dissolution rate, without introducing values for other parameters which conflict with other studies.

ELPHA: Dynamically deformable liver phantom for real-time motion-adaptive radiotherapy treatments.

Real-time motion-adaptive radiotherapy of intrahepatic tumors needs to account for motion and deformations of the liver and the target location within. Phantoms representative of anatomical deformations are required to investigate and improve dynamic treatments. A deformable phantom capable of testing motion detection and motion mitigation techniques is presented here. The dynamically dEformable Liver PHAntom (ELPHA) was designed to fulfill three main constraints: First, a reproducibly deformable anatomy is required. Second, the phantom should provide multimodality imaging contrast for motion detection. Third, a time-resolved dosimetry system to measure temporal effects should be provided. An artificial liver with vasculature was casted from soft silicone mixtures. The silicones allow for deformation and radiographic image contrast, while added cellulose provides ultrasonic contrast. An actuator was used for compressing the liver in the inferior direction according to a prescribed respiratory motion trace. Electromagnetic (EM) transponders integrated in ELPHA help provide ground truth motion traces. They were used to quantify the motion reproducibility of the phantom and to validate motion detection based on ultrasound imaging. A two-dimensional ultrasound probe was used to follow the position of the vessels with a template-matching algorithm. This detected vessel motion was compared to the EM transponder signal by calculating the root-mean-square error (RMSE). ELPHA was then used to investigate the dose deposition of dynamic treatment deliveries. Two dosimetry systems, radio-chromic film and plastic scintillation dosimeters (PSD), were integrated in ELPHA. The PSD allow for time-resolved measurement of the delivered dose, which was compared to a time-resolved dose of the treatment planning system. Film and PSD were used to investigate dose delivery to the deforming phantom without motion compensation and with treatment-couch tracking for motion compensation. ELPHA showed densities of 66 and 45HU in the liver and the surrounding tissues. A high motion reproducibility with a submillimeter RMSE (<0.32mm) was measured. The motion of the vasculature detected with ultrasound agreed well with the EM transponder position (RMSE<1mm). A time-resolved dosimetry system with a 1Hz time resolution was achieved with the PSD. The agreement of the planned and measured dose to the PSD decreased with increasing motion amplitude: A dosimetric RMSE of 1.2, 2.1, and 2.7cGy/s was measured for motion amplitudes of 8, 16, and 24mm, respectively. With couch tracking as motion compensation, these values decreased to 1.1, 1.4, and 1.4cGy/s. This is closer to the static situation with 0.7cGy/s. Film measurements showed that couch tracking was able to compensate for motion with a mean target dose within 5% of the static situation (-5% to +1%), which was higher than in the uncompensated cases (-41% to -1%). ELPHA is a deformable liver phantom with high motion reproducibility. It was demonstrated to be suitable for the verification of motion detection and motion mitigation modalities. Based on the multimodality image contrast, a high accuracy of ultrasound based motion detection was shown. With the time-resolved dosimetry system, ELPHA is suitable for performance assessment of real-time motion-adaptive radiotherapy, as was shown exemplary with couch tracking.

ESTIMATION OF ORGAN DOSES AND EFFECTIVE DOSES BASED ON IN-PHANTOM DOSIMETRY FOR PAEDIATRIC DIAGNOSTIC CARDIAC CATHETERISATION.

The present study evaluated the organ doses, effective doses and conversion factors from the dose-area product to effective dose in pediatric diagnostic cardiac catheterization performed by in-phantom dosimetry and Monte Carlo simulation. The organ and effective doses in 5-y-olds during diagnostic cardiac catheterizations were evaluated using radiophotoluminescence glass dosemeters implanted into a pediatric anthropomorphic phantom and PCXMC software. The mean effective dose was 3.8 mSv (range: 1.8-7.5 mSv). The conversion factors from the dose-area product to effective dose were 0.9 and 1.6 mSv (Gy cm2)-1 for posteroanterior and lateral fluoroscopy, respectively, and 0.9 and 1.5 mSv (Gy cm2)-1 for posteroanterior and lateral cineangiography, respectively. Effective doses evaluated using the pediatric dosimetry system agreed with those obtained using PCXMC software within 12%. The dose data and conversion factors evaluated may guide the estimation of exposure doses in children undergoing diagnostic cardiac catheterization.

CHARACTERIZATION OF A LITHIUM FORMATE EPR-DOSIMETRY SYSTEM FOR PROTON RADIATION THERAPY.

The specific aim for the characterization of the lithium formate dosimetry system is to determine response and stability in a proton beam. The long-term goal for this investigation is an audit system for proton therapy like the end-to-end dose determinations performed for radiotherapy with photons. For a 150-MeV proton beam, the dose response was found to be linear in the dose interval 0-8.8 Gy. The accuracy of dose reconstruction was controlled in a blind test, in which the dose of 6.63 Gy was measured in samples irradiated with a real dose of 6.70 Gy. The stability was determined by irradiations of sets of four dosimeters every week during 1 month and analyzed at the same day thereafter. The fitting of the fading curve was done with a second-order polynomial resulting in a 6.6% lower value compared to the reference after 31 d.

Investigation of Error Detection Capabilities of Various Patient-Specific Intensity Modulated Radiotherapy Quality Assurance Devices

The capability of error detection of patient-specific QA tools plays an important role in verifying MLC motion accuracy. The goal of this study was to investigate the capability in error detection of portal dosimetry, MapCHECK2 and MatriXX QA tools in IMRT plans. The 9 fields IMRT for 4 head and neck plans and 7 fields IMRT for 4 prostate plans were selected for the error detection of QA devices. The measurements were undertaken for the original plan and the modified plans, where the known errors were introduced for increasing and decreasing of prescribed dose (±2%, ±4% and ±6%) and position shifted in X-axis and Y-axis (±1, ±2, ±3 and ±5 mm). After measurement, the results were compared between calculated and measured values using gamma analysis at 3%/3 mm criteria. The average gamma pass for no errors introduced in head and neck plans was 96.9%, 98.6%, and 98.8%, while prostate plans presented 99.4%, 99.0%, and 99.7%, for portal dosimetry, MapCHECK2 and MatriXX system, respectively. In head and neck plan, the shifted error detections were 1 mm for portal dosimetry, 2 mm for MapCHECK2, and 3 mm for MatriXX system. In prostate plan, the shifted error detections were 2 mm for portal dosimetry, 3 mm for MapCHECK2, and 5 mm for MatriXX system. For the dose error detection, the portal dosimetry system could detect at 2% dose deviation in head and neck and 4% in prostate plans, while other two devices could detect at 4% dose deviation in both head and neck and prostate plans. Portal dosimetry shows slightly more capability to detect the error compared with MapCHECK2 and MatriXX system, especially in the complicated plan. It may be due to higher resolution of the detector; however, all three-detector types can detect various errors and can be used for patient-specific IMRT QA.

Feasibility of a dual detector system to perform transit dosimetry and MV imaging in-vivo

In this work, a dual detector system for simultaneous in-vivo dosimetry and MV imaging was investigated. The ability to measure real-time water equivalent dose post transit for a heterogeneous phantom was demonstrated, illustrating its advantage over non-water equivalent EPID dosimetry. Identification of incorrect MU delivery as well as patient misalignment can be identified in the dose profiles and confirmed through co-registration with EPID images. The dual detector comprising of a silicon array detector “Magic Plate” (MP) and an EPID was positioned beneath the patient couch at a source to detector distance of 150 cm. Two pseudo lung phantoms were utilised in this study; identical, except for the inclusion of a water equivalent hidden target mimicking a tumour. The dosimetric accuracy of the MP was evaluated with EBT3 film and TPS calculations. The presence and position of the hidden target was detected and accurately co-registered between the dose profiles measured with MP and the EPID image. The system measured a difference in post transit doses through the two phantoms of (5.0 ±1.6) cGy due to the presence of the target, in agreement with the TPS calculation of 5.16 cGy. The capability of the system for error detection was confirmed when a deliberate 7 mm lateral shift of the phantom was observed in both the dose profiles measured with MP and the EPID images. The MP as a dosimetric real time detector is lucent in MV photon fields and does not obstruct the EPID field of view.

Commissioning of portal dosimetry using a novel method for flattening filter-free photon beam in a nontrue beam linear accelerator

The aim of this study is to commission and validate the portal dosimetry (PD) system using an indirect method for flattening filter free (FFF) photon beam of the upgraded c-series linear accelerator. Varian Medical System clinacs with amorphous-silicon portal imager panel (aSi-1000) do not have PD for FFF beams. Recently, our c-series linear accelerator was upgraded to deliver 6MV FFF (6MVFFF) photon beam with the highest dose rate of 1400 monitor unit (MU)/min. The study, therefore, focuses on the commissioning and validation of PD for the 6MVFFF beam. An indirect method was implemented to predict the portal dose for FFF beam in Eclipse as the treatment planning system does not have direct prediction algorithm for FFF beam (version. 11). Dosimetrical characteristics of aSi-electronic portal imaging device (EPID) were evaluated for 6MVFFF beam and validation of PD for 6MVFFF beam was performed for open fields along with pretreatment quality assurance of intensity-modulated radiation therapy (IMRT), volumetric-modulated arc therapy (VMAT), and stereotactic radiosurgery (SRS) techniques for 30 patients planned with 6MVFFF beam. ASi-EPID saturates between 100 and 130 cm source to detector distance (SDD) for 6MVFFF beam and resolved at more than 140 cm SDD. The squared correlation coefficient (R2) for MU linearity was found to be 1 (R2 = 1), and instantaneous dose response linearity at different SDD's was found to be 0.999 (R2 = 0.999) for the 6MVFFF beam. Maximum gamma area index (GAI) for 3% dose difference and 3 mm distance-to-agreement criteria for IMRT, VMAT, and SRS/stereotactic radiotherapy plans was 97.9% ± 0.3%, 96.3% ± 0.5%, and 98.2% ± 0.2%, respectively. The results reveal that this novel method can be used to commission portal dosimetry for 6MVFFF beam as it is a convenient, faster, and accurate method.

Investigation of a Novel Decision Support Metric for Head and Neck Adaptive Radiation Therapy Using a Real-Time In Vivo Portal Dosimetry System.

In adaptive radiation therapy of head and neck cancer, any significant anatomical changes observed are used to adapt the treatment plan to maintain target coverage without elevating the risk of xerostomia. However, the additional resources required for adaptive radiation therapy pose a challenge for broad-based implementation. It is hypothesized that a change in transit fluence is associated with volumetric change in the vicinity of the target and therefore can be used as a decision support metric for adaptive radiation therapy. This was evaluated by comparing the fluence with volumetric changes in 12 patients. Transit fluence was measured by an in vivo portal dosimetry system. Weekly cone beam computed tomography was used to determine volume change in the rectangular region of interest from condyloid process to C6. The integrated transit fluence through the region of interest on the day of the cone beam computed tomography scan was calculated with the first treatment as the baseline. The correlation between fluence change and volume change was determined. A logistic regression model was also used to associate the 5% region of interest volume reduction replanning trigger point and the fluence change. The model was assessed by a chi-square test. The area under the receiver–operating characteristic curve was also determined. A total of 46 pairs of measurements were obtained. The correlation between fluence and volumetric changes was found to be −0.776 (P value <.001). The negative correlation is attributed to the increase in the photon fluence transport resulting from the volume reduction. The chi-square of the logistic regression was found to be 17.4 (P value <.001). The area under the receiver–operating characteristic curve was found to be 0.88. Results indicate the change in transit fluence, which can be measured without consuming clinical resources or requiring additional time in the treatment room, can be used as a decision support metric for adaptive therapy.

Characterisations of a fibre optic dosimetry system for source tracking during HDR Brachytherapy

Brachytherapy is a complex treatment procedure where radioactive sources are inserted in or close to the tumours to destroy the cancerous cells. Due to the unique properties of scintillation plastic detectors, this study was aimed to characterise an innovative fibre optic dosimetry system as a quality assurance tool during HDR Brachytherapy. Scintillating plastic fibres with different scintillation lengths were prepared and then optically coupled to non-scintillating fibres for light transmission. A transimpedance photodiode amplifier was used to detect positional sensitivities of different fibre probes placed within a solid-water phantom at varying distances above an 192-Ir brachytherapy source located within the catheter. Monte Carlo simulation has validated the expected response of the scintillating plastic fibres for multiple dwell positions with demonstrating the variance of detector response with source location. It showed the ability of shorter scintillating fibre lengths to distinguish between varying source locations when the SNR maintained high. However, fully scintillating plastic fibre showed flat response for most dwell positions. The proposed system proved to be appropriate for further clinical investigations, such as simultaneous dose measurement, and providing 3D position reconstruction through in-vivo source tracking.

Atmospheric dispersion modeling and radiological safety assessment for expected operation of Baiji nuclear power plant potential site

Installing new nuclear facilities require a serious consideration of safety measures throughout all stages. This work evaluates the radiological impact of the expected operations of potential Baiji nuclear power plant (NPP) in accord with the safety requirement’s achievement. GENII Environmental Dosimetry System is used to assess annual effective dose equivalent (AEDE) and cancer risks. GENII model configured according to ICRP 60 and 103 recommended dose conversion coefficients. Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model configured to study spatial distribution of the exposure dose around the NPP according to distance and direction. Results showed that maximum AEDE was 0.5 μSv at the Baiji potential site, which was lower than the allowed dose limit by International Commission on Radiological Protection (ICRP) 60 and 103 recommendations. The cancer incidence and fatality risks were in the range of 1 in 107 people. The areas most influenced by the atmospheric emissions of radioactive discharges were Baiji and Tikrit cities at distances of 30–40 km south and south-east of Baiji site.