Dose Monitoring System Research Articles

Preliminary study of a compact epithermal neutron absolute flux intensity measurement system for real-time in-vivo dose monitoring in boron neutron capture therapy

Boron neutron capture therapy (BNCT) is a radiotherapy technology that selectively kills tumor cells via the 10B(n, α)7Li reactions. Epithermal neutrons (0.5 eV–10 keV) are emitted and converted into thermal neutrons, which have a larger neutron capture reaction cross-section, by slowing down in the human body before reaching the tumor. Recently, the development of an epithermal neutron absolute flux intensity measurement technique has become crucial for real-time in-vivo dose monitoring in BNCT. In this study, a concept for a measurement system consisting of multiple compact scintillator with optical fibers detectors covered with neutron absorbers of various thicknesses is proposed. The designed system achieves a consistent response to epithermal neutrons with a theoretical coefficient of variation not higher than 5% for both LiCAF and EJ-254 scintillators. The theoretical feasibility of the proposed measurement system was investigated by an irradiation experiment carried out at the heavy water neutron irradiation facility at the Kyoto University Reactor. The experimental results indicated that further improvement and refinement are necessary to meet the high accuracy and precision required for real-time dose monitoring in clinical applications.

Calibration of the online dose monitoring system at the free-electron laser SwissFEL

The latest large-scale research facility of the Paul Scherrer Institute, the x-ray free-electron laser SwissFEL, is installed in a 740 m long building. The facility accelerates electrons to a maximal energy of 5.8 GeV with repetition rates up to 100 Hz. The building is integrated in a regional recreation area with shielding of the accelerator vault dimensioned to tolerate temporary beam losses. An online dose monitoring system capable of shutting down SwissFEL ensures compliance with legal requirements. The studies present an overview of the evaluation of calibration factors for this system and results of dedicated benchmark measurements, carried out to verify underlying assumptions and simplifications.

Estimating brain and eye lens dose for the cardiologist in interventional cardiology-are the dose levels of concern?

To establish conversion coefficients (CCs), between mean absorbed dose to the brain and eye lens of the cardiologist and the air kerma-area product, PKA, for a set of projections in cardiac interventional procedures. Furthermore, by taking clinical data into account, a method to estimate the doses per procedure, or annual dose, is presented. Thermoluminescence dosimeters were used together with anthropomorphic phantoms, simulating a cardiologist performing an interventional cardiac procedure, to estimate the CCs for the brain and eye lens dose for nine standard projections, and change in patient size and x-ray spectrum. Additionally, a single CC has been estimated, accounting for each projections fraction of use in the clinic and associated PKA using clinical data from the dose monitoring system in our hospital. The maximum CCs for the eye lens and segment of the brain, is 5.47 μGy/Gycm2 (left eye lens) and 1.71 μGy/Gycm2 (left brain segment). The corresponding weighted CCs: are 3.39 μGy/Gycm2 and 0.89 μGy/Gycm2, respectively. Conversion coefficients have been established under actual scatter conditions, showing higher doses on the left side of the operator. Using modern interventional x-ray equipment, interventional cardiac procedures will not cause high radiation dose levels to the operator when a ceiling mounted shield is used, otherwise there is a risk that the threshold dose values for cataract will be reached. In addition to the CCs for the different projections, methods for deriving a single CC per cardiac interventional procedure and dose per year were introduced.

Establishment of dose monitoring system for dentistry

Along with the advancement of dental x-ray equipment, the use of diagnostic radiation has been rapidly increasing. Accordingly, concerns about radiation exposure are increasing. In particular, imaging examinations inthe dental field have a low individual radiation exposure. However, the frequency of the examinations is high.Also, due to the abundant usage of dental CBCT, concerns has been widely spread across the users and the nation. In response to this, there has been a need to establish a dose monitoring system for dental x-ray equipment.Therefore, the purpose of this study was to establish of a national dose monitoring system for imaging examinations in the dentistry. For the system establishment, the structure of intraoral, panoramic radiography and CBCT system was surveyed and the integrated data collection plan was prepared. Based on this, dose monitoring system, which can be utilized for nation-wide, was established and a pilot operation was conducted. In orderto continuously expand the system in the future, system supplements should be confirmed through gatheringexpert opinions.

Imaging in pediatric traumatology and orthopedics

Conventional or digital radiography is still the basis of imaging diagnostics of the skeletal system in pediatric patients. It is considered the gold standard for diagnosis, treatment selection, and follow-up. In addition, procedures such as ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and also nuclear medicine techniques can and should be used. It is advantageous to use trained radiology technicians who are familiar with the handling of children in X‑ray diagnostics. If there is no dedicated pediatric radiology department, it is recommended to follow the guidelines from radiology societies (as low as reasonably achievable [ALARA]) and radiation protection commissions. The present article describes how state-of-the-art tools such as dose monitoring systems and software-controlled image processing and also postprocessing can be used. The article provides information on how the various modalities can be optimally used in order to achieve the best result, i.e., diagnosis, with the least possible effort and burden for the child.

A compact scintillator-based detector with collimator and shielding for dose monitoring in boron neutron capture therapy

Boron neutron capture therapy exploits 10B(n,α)7Li reactions for targeted tumor destruction. In this work, we aimed at developing a dose monitoring system based on the detection of 478keV gamma rays emitted by the reactions, which is very challenging due to the severe background present. We investigated a compact gamma-ray detector with a pinhole collimator and shielding housing. Experimental nuclear reactor measurements involved varying boron concentrations and artificial shifts of the sources. The system successfully resolved the 478keV photopeak and detected 1cm lateral displacements, confirming its suitability for precise boron dose monitoring.

RADIATION EXPOSURE IN INTERVENTIONAL CARDIOLOGY: STRATEGIES FOR REDUCTION AND PROTECTION

Occupational radiation exposure is a significant concern among healthcare professionals, particularly those in interventional radiology and cardiology procedures. This study aims to comprehensively investigate radiation exposure and its health effects among 200 healthcare professionals, including 100 physicians, 50 nurses, and 50 technicians, across five hospitals. The study employed a controlled, multi-center, observational design, with 100 participants in the experimental group exposed to enhanced radiation protection strategies, while 100 participants in the control group adhered to standard safety protocols. The interventions included additional lead barriers, radiation-absorbent pads, real-time dose monitoring systems, and continuous staff training on radiation safety. Exposure levels were measured using personal dosimeters at regular intervals before and after the interventions. Subgroup analysis was conducted based on professional roles and procedure types, categorized into simple and complex interventions. The results showed a statistically significant reduction in annual radiation exposure in the experimental group compared to the control group, with substantial effect sizes. Subgroup analysis revealed varying degrees of exposure reduction among different professional roles. Notably, complex interventions demonstrated the most substantial reductions in radiation exposure. Furthermore, an analysis of X-ray beam angles indicated a statistically significant increase in exposure at steep angles (≥30°). However, no significant interaction between the control and experimental groups was observed, suggesting that other variables may influence the relationship between steep angles and exposure. The findings of this study emphasize the effectiveness of enhanced protection strategies in reducing occupational radiation exposure among healthcare professionals. The nuanced effects observed across different professional roles and procedure types underscore the importance of tailored safety measures. These results contribute to the ongoing efforts to optimize radiation safety in medical settings and promote the well-being of healthcare professionals. Ethical considerations, adherence to international standards, and the potential implications for policy and guidelines further underscore the significance of this study's findings.

Establishment of Hp(3) calibration system for eye dose monitoring in Taiwan.

In response to the ICRP's amending the occupational exposure limit for the eye lens, the Institute of Nuclear Energy Research (INER) established the Hp(3) calibration system for eye dose monitoring in Taiwan to accurately assess the dose received in the eye lens. INER employed the narrow-spectrum series radiation according to the ISO 4037 as the X-ray radiation qualities, and the measured half-value layer consistent with a 5% difference. The air kerma rate standard was determined by the self-made free air chamber, and through dose conversion coefficient referring to ISO 4037 to obtain the Hp(3) on an ISO cylinder phantom. Furthermore, the calibration system was provided as the characteristics tests for DOSIRIS headset dosemeters. Finally, the Hp(3) calibration system has been established in Taiwan, and it can be used to provide calibration services for eye lens dosemeters and be applied to the proficiency testing that will be held in 2023.

Fast dose calculation in x-ray guided interventions by using deep learning

Objective. Patient dose estimation in x-ray-guided interventions is essential to prevent radiation-induced biological side effects. Current dose monitoring systems estimate the skin dose based in dose metrics such as the reference air kerma. However, these approximations do not take into account the exact patient morphology and organs composition. Furthermore, accurate organ dose estimation has not been proposed for these procedures. Monte Carlo simulation can accurately estimate the dose by recreating the irradiation process generated during the x-ray imaging, but at a high computation time, limiting an intra-operative application. This work presents a fast deep convolutional neural network trained with MC simulations for patient dose estimation during x-ray-guided interventions. Approach. We introduced a modified 3D U-Net that utilizes a patient’s CT scan and the numerical values of imaging settings as input to produce a Monte Carlo dose map. To create a dataset of dose maps, we simulated the x-ray irradiation process for the abdominal region using a publicly available dataset of 82 patient CT scans. The simulation involved varying the angulation, position, and tube voltage of the x-ray source for each scan. We additionally conducted a clinical study during endovascular abdominal aortic repairs to validate the reliability of our Monte Carlo simulation dose maps. Dose measurements were taken at four specific anatomical points on the skin and compared to the corresponding simulated doses. The proposed network was trained using a 4-fold cross-validation approach with 65 patients, and evaluating the performance on the remaining 17 patients during testing. Main results. The clinical validation demonstrated a average error within the anatomical points of 5.1%. The network yielded test errors of 11.5 ± 4.6% and 6.2 ± 1.5% for peak and average skin doses, respectively. Furthermore, the mean errors for the abdominal region and pancreas doses were 5.0 ± 1.4% and 13.1 ± 2.7%, respectively. Significance. Our network can accurately predict a personalized 3D dose map considering the current imaging settings. A short computation time was achieved, making our approach a potential solution for dose monitoring and reporting commercial systems.

Patient exposure during videofluoroscopic swallowing studies performed by speech-language pathologists.

Videofluoroscopic swallowing studies (VFSSs) are fluoroscopic examinations performed by speech and language pathologists (SLPs), for the evaluation of the oral and pharyngeal phases of swallowing, in patients who are diagnosed with symptoms like dysphagia and speech impairment. The study was focused on the evaluation of the patient doses from VFSS performed at Hamad Medical Corporation hospitals. Data on the patient exposure and examination parameters were extracted from the Radiation Dose Monitoring system, statistically analysed and compared with literature. For adult patients, the mean (median) values for fluoroscopy time and kerma-air product were 2.8 (2.7) min and 181 (144) cGycm2, respectively. For children, the respective mean (median) values were 2.6 (2.4) min and 15.3 (9.2) cGycm2. The results of the study indicate that the VFSS are performed by well-trained health professionals, and as a result, image quality sufficient for a confident diagnosis is obtained at relatively low dose levels.

Deep TL: progress of a machine learning aided personal dose monitoring system.

Personal dosemeters using thermoluminescence detectors can provide information about the irradiation event beyond the pure dose estimation, which is valuable for improving radiation protection measures. In the presented study, the glow curves of the novel TL-DOS dosemeters developed by the Materialprüfungsamt NRW in cooperation with the TU Dortmund University are analysed using deep learning approaches to predict the irradiation date of a single-dose irradiation of 10mGy within a monitoring interval of 41d. In contrast of previous work, the glow curves are measured using the current routine read-out process by pre-heating the detectors before the read-out. The irradiation dates are predicted with an accuracy of 2-5d by the deep learning algorithm. Furthermore, the importance of the input features is evaluated using Shapley values to increase the interpretability of the neural network.

Making CT Dose Monitoring Meaningful: Augmenting Dose with Imaging Quality.

Due to the concerns about radiation dose associated with medical imaging, radiation dose monitoring systems (RDMSs) are now utilized by many radiology providers to collect, process, analyze, and manage radiation dose-related information. Currently, most commercially available RDMSs focus only on radiation dose information and do not track any metrics related to image quality. However, to enable comprehensive patient-based imaging optimization, it is equally important to monitor image quality as well. This article describes how RDMS design can be extended beyond radiation dose to simultaneously monitor image quality. A newly designed interface was evaluated by different groups of radiology professionals (radiologists, technologists, and physicists) on a Likert scale. The results show that the new design is effective in assessing both image quality and safety in clinical practices, with an overall average score of 7.8 out of 10.0 and scores ranging from 5.5 to 10.0. Radiologists rated the interface highest at 8.4 out of 10.0, followed by technologists at 7.6 out of 10.0, and medical physicists at 7.5 out of 10.0. This work demonstrates how the assessment of the radiation dose can be performed in conjunction with the image quality using customizable user interfaces based on the clinical needs associated with different radiology professions.

THE DEVELOPMENT OF GAMMA RADIATION DOSIMETERS REAL-TIME NETWORK-BASED SENSOR WIRELESS IEEE 802.15.4 PROTOCOL

Several studies have been carried out on the development of real-time gamma radiation dosimeter based on the wireless sensor network (WSN) protocol IEEE 802.15.4. WSN technology can be adopted to develop a gamma radiation dose monitoring system on a large scale due to its real-time, centralized, efficient, and relatively low-cost attributes. This study aims to develop a personal radiation dosimeter that can collect data from the measurement results of several sensor nodes or multi-sensors. The measurement results of radiation dose values from many radiation workers are sent to a coordinator node consisting of the Xbee module and Arduino as a microcontroller. The system test is compared with a calibrated dosimeter reading and is expected to be one of the instruments for determining radiation dose in real-time. It can also reduce the risk of receiving a radiation dose that exceeds the threshold allowed by the ionizing control agency and a program in radiation protection. Changes in the intensity of radiation emitted by Cs-137 (gamma radiation) are carried out by varying each detector's distance to the source, which indirectly varies the value of the dose rate received by the detector. This relationship is shown from the value of R2 = 0.99, which indicates a strong correlation between changes in the dose given to the detector's response being developed. The system built is efficient, inexpensive, and collecting radiation exposure data can monitor radiation exposure received by workers in real-time. This technique can help speed up reporting of radiation exposure received by radiation workers.

A Prototype Software System for Intra-procedural Staff Dose Monitoring and Virtual Reality Training for Fluoroscopically Guided Interventional Procedures.

Staff dose management in fluoroscopically guided interventional procedures is a continuing problem. The scattered radiation display system (SDS), which our group has developed, provides in-room visual feedback of scatter dose to staff members during fluoroscopically guided interventional (FGI) procedures as well as extra-procedure staff and resident training. There have been a number of virtual safety training systems developed that provide detailed feedback for staff, but utilize expensive graphics processing units (GPUs) and dosimeter systems, or interaction with the x-ray system in a manner which entails additional radiation exposure and is not compatible with the As Low as Reasonably Achievable paradigm. The SDS, on the other hand, incorporates a library of look-up-table (LUT) room scatter distributions determined using the EGSnrc Monte Carlo software, which facilitates accurate and rapid system update without the need for GPUs. Real-time display of these distributions is provided for feedback to staff during a procedure. After a procedure is completed, machine parameter and staff position log files are stored, retaining all of the exposure and geometric information for future review. A graphic user interface (GUI) in Unity3D enables procedure playback and interactive virtual-reality (VR) staff and resident training with virtual control of exposure conditions using an Oculus headset and controller. Improved staff and resident awareness using this system should lead to increased safety and reduced occupational dose.

Monitoring cone-beam CT radiation dose levels in a University Hospital.

To present patient dose levels for different CBCT scanners, acquired by a dose monitoring tool in a University Hospital, as a function of field of view (FOV), operation mode, and patient age. An integrated dose monitoring tool was used to collect radiation exposure data [type of CBCT unit, dose-area product (DAP), FOV size, and operation mode] and patient demographic information (age, referral department) performed on a 3D Accuitomo 170 and a Newtom VGI EVO unit. Effective dose conversion factors were calculated and implemented into the dose monitoring system. For each CBCT unit, the frequency of examinations, clinical indications, and effective dose levels were obtained for different age and FOV groups, and operation modes. A total of 5163 CBCT examinations were analyzed. Surgical planning and follow-up were the most frequent clinical indications. For the standard operation mode, effective doses ranged from 35.1 to 300 µSv and 9.26-117 µSv using 3D Accuitomo 170 and Newtom VGI EVO, respectively. In general, effective doses decreased with increasing age and FOV size reduction. Effective dose levels varied notably between systems and operation modes.Operation mode selection and FOV size were indication-oriented, with larger FOV sizes election serving surgical planning and follow-up. Seeing the influence of FOV size on effective dose levels, manufacturers could be advised to move toward patient-specific collimation and dynamic FOV selection. Systematically monitoring patient doses could be recommended for steering future CBCT optimization.

A spectroscopic and imaging gamma-detector prototype towards dose monitoring in BNCT

We report the performances of a compact gamma-ray detection prototype, based on a 2” LaBr3 scintillator crystal coupled to a matrix of 64 SiPMs, designed as a single unit for a future SPECT system for dose monitoring in BNCT. The aim of the module is to detect the 478 keV gamma rays emitted by the boron neutron capture reactions, in order to map the 10B distribution in the patient. The spectroscopic capabilities of the module have been validated by irradiating borated vials with thermal neutrons fluxes in the order of 1 × 105 n/cm2/s. The good energy resolution of the detector (2.7% at 662 keV) has allowed to resolve the boron neutron capture photopeak, achieving excellent linear correlation between the number of detected events at 478 keV and the boron concentration in the vials irradiated. Preliminary imaging results based on a Convolutional Neural Network and obtained by irradiating a 5 cm × 5 cm × 2 cm square crystal with a 1 mm collimated 137Cs source (662 keV) are also reported.

Identification and characterization of patients being exposed to computed-tomography associated radiation-doses above 100 mSv in a real-life setting.

Rationale and objectivesPatients receiving high cumulative effective doses (CED) from recurrent computed tomography (CT) in a real-life setting are not well identified. Evaluation of causes and patient characteristics may help to define individuals potentially at risk of radiation-induced secondary malignancies. Materials and methodsPatients who received a CED > 100 mSv from CT scans during October 2012 and April 2020 at a tertiary university center were identified with the help of a radiological radiation dose monitoring system. The primary disease and referral diagnosis, number of CT exams, time period, age, BMI and gender distribution of the 1000 patients with the highest CED were analysed. Results3431 patients had a CED of more than 100 mSv, which corresponded to 2.75% of all patients who received a CT exam. From the 1000 patients with the highest CED, mean number of CT exams per patient was 14.6, mean CED was 257 mSv (SD 98, range 177–1339). Mean age of patients was 63.9 years (SD 10.6), male to female ratio 3:2, and mean BMI 28.7 kg/m2 (SD 5.5). 728 (72.9%) patients had cancer. The leading primary diagnosis was liver cirrhosis in 197 patients and 103 patients had a liver transplantation. In patients with liver cirrhosis, 750 exams were indicated for the follow-up of the disease, 662 for the clarification of an acute clinical condition, and 202 for CT-guided stereotactic radiofrequency ablation. ConclusionRecurrent CT scans of patients with cancer, liver cirrhosis and liver transplantation may lead to critically high CED.

Experimental validation of a spectroscopic gamma-ray detector based on a LaBr3 scintillator towards real-time dose monitoring in BNCT

We report the experimental validation of a detection module based on a LaBr3(Ce＋Sr) scintillator crystal, read by a matrix of Silicon Photomultipliers (SiPMs), for the development of a SPECT system for dose monitoring in Boron Neutron Capture Therapy (BNCT). The goal of the system is to detect the gamma rays at 478keV emitted by the excited 7Li produced in the 10B(n, α)7Li reaction, to have a real-time localization and quantification of the local dose released to a patient during BNCT treatment. The good energy resolution of the detector (<3% at 662keV) allows to resolve the photopeak at 478keV from the adjacent annihilation photons photopeak at 511keV, originated from pair production of high energy gamma rays, such as the hydrogen neutron capture gamma rays at 2.2MeV. The results shown in this article demonstrate the suitability of our detector in view of future application in BNCT real-time dose monitoring. Good linearity (RMSE < 2.5cps) between the number of events detected at 478keV and the boron concentration of the 10B-loaded samples has been achieved, down to a boron concentration of 62ppm with a neutron flux of approximately 1 × 105 n/cm2/s.

Low noise optimization of an electron beam current transformer for conventional radiotherapy up to ultra high dose rate irradiations

Ultra high dose rate electron beams also known as FLASH radiotherapy is becoming of importance in several preclinial cancer treatment studies. However, due to the dose rate used during the irradiation sessions, no real time dose monitoring device exists to date. In this work, we present the development of a beam current transformer (BCT), from the choice of the ferromagnetic component and the realisation of the shielding to the design of a front-end electronics based on a trans-impedance circuit in order to perform a low noise optimization of the detector. The BCT prototype is able to monitor a beam current range from 1.2 μA to 200 mA with a rise time constant better than 20 ns and a droop rate of the signal below 0.05% · μs-1. Preliminary in-situ measurements are also presented. The goal is to combine the BCT system which measure in real time the beam current, to an ionisation chamber monitoring the beam shape and position in order to provide a reliable dose monitoring system.

Investigations Into the Suitability of Bacterial Suspensions as Biological Indicators for Low-Energy Electron Irradiation.

Low-energy electron irradiation is an emerging alternative technology for attenuated or complete pathogen inactivation with respect to medical, biotechnological, and pharmaceutical applications. Pathogen inactivation by ionizing radiation depends mainly on the absorbed electron dose. In low-energy electron irradiation processes, determination of the absorbed electron dose is challenging due to the limited, material-dependent penetration depth of the accelerated electrons into the matter. In general, there are established dosimetry systems to evaluate the absorbed dose under dry irradiation conditions. However, there is no system for precise dose monitoring of low-energy irradiation processes in liquids or suspensions so far. Therefore, in this study three different bacterial species were investigated as biological dose indicators, especially in the range of low doses (< 6.5 kGy) in aqueous solutions or suspensions. Escherichia coli, Bacillus subtilis, and Staphylococcus warneri were comparatively evaluated for their suitability as biological dose indicators. Thin homogeneous films of the respective bacterial suspensions were irradiated with increasing doses of low-energy accelerated electrons. The average absorbed dose was determined using a colorimetric dosimeter based on a tetrazolium salt solution. The maximum and minimum absorbed doses were measured with a referenced film dosimeter. Subsequently, the inactivation kinetics was determined in terms of inactivation curves and D10 values. Thus, the minimum inactivation dose of bacterial growth was assessed for E. coli and S. warneri. The effect of irradiation with low-energy accelerated electrons on the growth behavior and activity of the bacteria was studied in more detail using impedance spectroscopy. With increasing irradiation doses growth was delayed.