Electronic Personal Dosimeters Research Articles

Commissioning of the first hospital-based PET radiopharmaceutical cyclotron in Greece: Personnel dose assessment.

The role of positron emission tomography (PET) imaging with 2-fluoro-2-deoxy-D-glucose (FDG) is well established in the diagnosis and management of cancer patients. As the demand for PET imaging continues to rise, many hospitals are installing on-site self-shielded mini cyclotrons to produce their own radiopharmaceuticals, including FDG. In May 2021, the Dose-on-Demand Biomarker Generator (BG-75) was installed at the Metaxa Cancer Hospital in Greece, making it the first hospital-based PET radiopharmaceutical cyclotron in the country. During commissioning, the expected external exposure for personnel was established, and internal exposure was found to be negligible. Personnel dose was estimated with two methods: survey meter measurements in various locations combined with the time spent in each location, and direct measurement using electronic personal dosemeters. Gamma and neutron radiation readings outside the cyclotron vault were at background levels. Inside the cyclotron vault, the highest recorded readings by the target were 18 μSv/h for both gammas and neutrons; at one meter, the values were 5 μSv/h and 4 μSv/h, respectively. Based on these measurements, the annual expected whole-body dose per operator is 0.6 mSv, and the respective extremity dose is 16 mSv. The annual expected whole body and extremity dose for the radiochemist is 0.3 mSv and 25 mSv, respectively. The expected dose estimates for the medical physicists are also below 1 mSv. These doses are well below the regulatory limits and local As Low As Reasonably Achievable (ALARA) levels. With experience and a robust ALARA program, personnel exposure could be further reduced.&#xD.

Alerts to improve occupational protection during Interventional Radiology. More attention is needed for simple but frequent procedures

Occupational protection could be improved in interventional radiology. The monthly personal dosimetry cannot alert on some occupational doses with anomalous values for certain procedures. Active electronic personal dosimeters linked wireless to a dose management system (DMS), allow for the measurement of occupational doses per procedure, integrating this information with patient dose indicators and with technical and geometrical conditions of the procedures.We analysed around 3100 occupational dose values for individual procedures collected during the last two years, in an interventional radiology laboratory of a University Hospital and two groups, with patient doses higher than 100 Gy.cm2, and lower than 30 Gy.cm2.An unshielded reference dosimeter located at the C-arm registers the ambient dose equivalent (ADE) per procedure to be compared with the personal dose equivalent (PDE) over the apron. The ratio between both values PDE/ADE is a good indication of occupational protection. Alerts for occupational protection optimisation are suggested.For the full sample, 8.4 % of occupational doses measured over the protective apron of the interventionists were higher than 100 µSv and 3.8 % higher than 200 µSv per procedure. Occupational protection for complex procedures (>100 Gy.cm2) had median values of 46 µSv for PDE and 3.3 % for PDE/ADE. However, for simple procedures, (<30 Gy.cm2) the median values were 10 µSv and 28.4 %. This last percentage is 9 times higher than the value for complex procedures. This lack of protection should be corrected and the need to reduce some occupational doses reinforced in radiation protection training programmes for interventionists.

Reduction of Radiation Risk to Cardiologists and Patients during Coronary Angiography: Effect of Exposure Angulation and Composite Shields

Purpose: This study aimed to design an improved form of a composite shield with different materials and shapes and simultaneously reduce the radiation dose to both the patient and operator.&#x0D; Materials and Methods: A female phantom study was performed with and without bismuth belt-shaped composite shields on the breast region at different beam projections used in coronary angiography. Dose measurements were conducted using GR-200 thermo-luminescence dosimeters, dose area product (DAP), and air kerma (AK) over regular and large breast locations, with and without using bismuth shields. An electronic personal dosimeter was used for operator dose assessment. Patients received doses between 2.27 mSv and 3.38 mSv, depending on the size and strength of beam projections.&#x0D; Results: The use of the developed shields caused a dose reduction of 18%–25% of sensitive breast tissue due to breast size and shield type. During coronary angiography, the mean values of DAP and AK were 2.02 (1.24-2.80) mGy.m2 and 314.1 (202.8-500) mGy, respectively. The highest recorded dose was at the LAO/CRA and LAO/CAU beam projections for both the patient and operator. After applying a belt shield, the operator's radiation dose was decreased by approximately 32%. We found a statistically significant correlation between the radiation dose received by the operator and the patient's breast radiation exposure dose (p&lt;0.001, r2=0.93).&#x0D; Conclusion: The designed belt shield can be a potentially promising protective device for decreasing the radiation risk to the patient's breast and the operator during coronary angiography. However, further studies will be considered before the application of this shield in standard clinical practice.

Smart City and the digital measurement of solar ultraviolet radiation in Outdoor workers in the City of Lisbon

Abstract The growing incidence of skin cancer over the years has made it a significant public health problem. However, technology can be used to tackle the skin cancer which is highly preventable, mainly through reduced exposure to solar ultraviolet radiation (UVR). Digital services can be used to promote individual and collective protective measures and interventions. Specifically, there is an opportunity when the exposure is intermittent or continuous, and occurs in an occupational or leisure setting. We are using a digital platform to contribute to raising public and policy awareness on solar UVR-inflicted occupational skin cancers in the municipality of Lisbon. The digital platform is performing direct measurements of the solar UVR dose received by outdoor workers. Results will likely contribute to further understanding the risk estimates for keratinocyte cancer estimations in this population. The digital platform integrates a personal electronic dosimeter (GENESIS-UV system) to assess occupational solar UVR doses of gardeners, masons, and gravediggers of the municipality of Lisbon. Two hundred and ten outdoor workers were selected to wear the dosimeter for 1 month each, between April and October during their daily working hours. The digital platform that offers private access to information through dashboard visualization provided information for the outdoor workers and facilitate communication with the participants. Study data provides the outdoor workers with information on their personal solar UVR exposure during their working hours and an estimate of their risk of developing skin cancer. The results prospectively should flow into the design of adequate prevention campaigns for skin cancer in outdoor workers.

Photon spectra in NPL standard monoenergetic neutron fields.

A High Purity Germanium (HPGe) detector has been used to measure the photon spectra in the majority of monoenergetic neutron fields produced at NPL (0.144, 0.250, 0.565, 2.0, 5.0 and 16.5MeV). The HPGe was characterised and then modelled to produce a response matrix. The measured pulse height spectra were then unfolded to produce photon fluence spectra. The new spectra were used to improve the photon to neutron dose equivalent ratios from some earlier work at NPL with Geiger-Muller tubes and electronic personal dosemeters.

PDOZ: innovative personal electronic dosimeter for electron and gamma H *(d) dosimetry

The personal (or active) electronic dosimeters (PEDs) are devices used to determine the individual exposure to ionizing radiations and they are employed in hospitals, research laboratories and nuclear power plants. The PDOZ project is a personal electronic dosimeter able to detect, discriminate and measure the delivered dose by beta particles and gamma rays. In this paper, several Monte Carlo simulations are described. The first one is regarding the ICRU sphere, [11,12] implemented to evaluate the ambient dose equivalent, H *(10), and the fluence-to-dose equivalent conversion coefficients for gamma rays and beta particles. The second simulation is carried out to study the prototype dosimeter response to gamma rays and beta particles and, also thanks to previous one, to obtain the conversion curve necessary to calculate the ambient dose equivalent from the silicon photomultipliers counts. In the last one, instead, the performance of a prototype dosimeter, composed by a small plastic scintillator coupled to two SiPMs, is evaluated and a simulation with different radioactive sources is made whose results are compared with the experimental measurements. All simulations are carried out by Geant4 including the optical photon transport.

DOIN: a novel electronic personal dosemeter for neutrons

Electronic personal dosemeters (EPD) are powerful tools for achieving ALARA (As Low As Reasonably Achievable) objectives in operational radiation protection. EPD for photons are well developed and their performances usually comply with relevant Standards. By contrast, a very few commercial models exist for neutrons and their energy dependence is too large for using them without pre-information on the workplace neutron spectrum. Within the INFN-based DOIN (DOsimetro Indossabile per Neutroni) project, a new EPD for neutrons was prototyped. Owing to a new patented design, a good dose response was achieved in the energy interval from thermal neutrons up to the quality of ^{241}Am-Be. The response is nearly isotropic and, if compared to commercial models, exhibits higher sensitivity.

Digitally measuring solar ultraviolet radiation in outdoor workers: A study protocol for establishing the use of electronic personal dosimeters in Portugal.

The rising incidence of skin cancer over the years has made it a significant public and occupational health issue. However, skin cancer is highly preventable, mainly through reduced exposure to solar ultraviolet radiation (UVR), which can be achieved by a variety of individual and collective protective measures and interventions. The relative risk associated with different patterns of exposure to solar UVR differs for the subtypes of keratinocyte cancers (KC). Specifically, whether the exposure is intermittent or continuous, and occurs in an occupational or leisure/recreational setting. The main aim of the study using this protocol is to contribute to raising public and policy awareness on solar UVR-inflicted occupational skin cancers in Lisbon. This will be achieved by performing direct measurements of the solar UVR dose received by outdoor workers using a digital platform. Results will likely contribute to further understanding the risk estimates for keratinocyte cancer estimations in this population. A prospective observational study will be conducted in Lisbon, Portugal. Personal electronic dosimeters (GENESIS-UV system) integrated with a digital platform will be used to assess occupational solar UVR doses of gardeners, masons, and gravediggers of the municipality of Lisbon. Two hundred and ten outdoor workers will be selected to wear the dosimeter for 1 month each, between April and October during their daily working hours. A digital web-based platform that offers private access to information through dashboard visualization will provide information for the outdoor workers and facilitate communication with the participants. The expected results of the overall proposal comprise the occupational solar UVR doses, expressed in standard erythemal dose (SEDs) per day of outdoor work for 7 months. Study data will provide outdoor workers with information on their personal solar UVR exposure during their working hours and an estimate of their risk of developing skin cancer. It is expected that the occupational solar UVR doses of the outdoor workers in Portugal will be above the threshold of 1 to 1.33 SED/day, due to the latitude of Lisbon and the nature of the occupations. The results prospectively should flow into the design of adequate prevention campaigns for skin cancer in outdoor workers.

Occupational and patient doses for interventional radiology integrated into a dose management system.

The International Commission on Radiological Protection recommends managing patient and occupational doses as an integrated approach, for the optimisation of interventional procedures. The conventional passive personal dosimeters only allow one to know the accumulated occupational doses during a certain period of time. This information is not enough to identify if there is a lack of occupational radiation protection during some procedures. This paper describes the use of a dose management system (DMS) allowing patient and occupational doses for individual procedures to be audited. The DMS manages patient and occupational doses measured by electronic personal dosimeters. One dosemeter located at the C-arm is used as a reference for scatter radiation. Data have been collected from five interventional rooms. Dosimetry data can be managed for the whole procedure and the different radiation events. Optimisation is done through auditing different sets of parameters for individual procedures: patient dose indicators, occupational dose values, the ratio between occupational doses, and the doses measured by the reference dosemeter at the C-arm, and the ratio between occupational and patient dose values. The managed data correspond to the year 2021, with around 4500 procedures, and 8000 records on occupational exposures. Patient and staff dose data (for 11 cardiologists, 7 radiologists and 8 nurses) were available for 3043 procedures. The DMS allows alerts for patient dose indicators and occupational exposures to be set. The main advantage of this integrated approach is the capacity to improve radiation safety for patients and workers together, auditing alerts for individual procedures. The management of patient and occupational doses together (measured with electronic personal dosimeters) for individual interventional procedures, using dose management systems, allows alerting optimisation on high-dose values for patients and staff.

Personal neutron dosimetry: State-of-the-art and new technologies

Neutron personal dosimetry is necessary for the monitoring of exposed workers, not only in nuclear industry and related activities but also in the growing number of neutron producing facilities, so new techniques and devices are continuously developed and improved. This article provides a review of the present state-of-the-art as well as the main new results and innovative developments in neutron personal dosimetry using electronic personal dosimeters (EPDs), track dosimeters (etched track dosimeters, FNTD), luminescent dosimeters (TL, OSL, RPL), superheated drop dosimeters and direct ion storage (DIS) dosimeters.

Radiation exposure to nuclear medicine technologists performing a V/Q PET: Comparison with conventional V/Q scintigraphy, [18F]FDG PET and [68Ga]Ga DOTATOC PET procedures.

Ventilation/Perfusion (V/Q) PET/CT is an emerging imaging modality for regional lung function evaluation. The same carrier molecules as conventional V/Q scintigraphy are used but they are radiolabelled with gallium-68 (68Ga) instead of technetium-99m (99mTc). A recurrent concern regarding V/Q PET imaging is the radiation dose to the healthcare workers. The aim of this study was to evaluate the total effective dose and the finger dose received by the technologist when performing a V/Q PET procedure, and to compare them with the radiations doses received with conventional V/Q scintigraphy, FDG PET and Ga DOTATOC PET procedures. The whole body dose measurement was performed 10 times for each of the evaluated procedures using an electronic personal dosimeter (ED). For V/Q PET and V/Q scintigraphy procedures, ventilation and perfusion stages were separately evaluated. Internal exposure was measured for ventilation procedures. Finger dose measurements were performed 5 times for each of the PET procedures using Thermoluminescence (TL) pellets. The technologist effective dose when performing a V/Q PET procedure was 2.83 ± 0.67 μSv, as compared with 1.16 ± 0.34 μSv for conventional V/Q scintigraphy, 2.13 ± 0.77 μSv for [68Ga]Ga-DOTATOC, and 2.86 ± 1.79 μSv for FDG PET procedures, respectively. The finger dose for the V/Q PET procedure was similar to the dose for a [68Ga]Ga-DOTATOC scan (0.35 mSv and 0.32 mSv, respectively). The technologist total effective dose for a V/Q PET procedure is ~2.4 higher than the dose for a conventional V/Q scintigraphy, but in the same range than the radiation exposure when performing common PET procedures, both in terms of total effective dose or finger dose. These results should be reassuring for the healthcare workers performing a V/Q PET procedure.

Whole-body radiation exposure in Trauma and Orthopaedic surgery.

The use of fluoroscopy in orthopaedic surgery creates risk of radiation exposure to surgeons. Appropriate personal protective equipment (PPE) can help mitigate this. The primary aim of this study was to assess if current radiation protection in orthopaedic trauma is safe. The secondary aims were to describe normative data of radiation exposure during common orthopaedic procedures, evaluate ways to improve any deficits in protection, and validate the use of electronic personal dosimeters (EPDs) in assessing radiation dose in orthopaedic surgery. Radiation exposure to surgeons during common orthopaedic trauma operations was prospectively assessed using EPDs and thermoluminescent dosimeters (TLDs). Normative data for each operation type were calculated and compared to recommended guidelines. Current PPE appears to mitigate more than 90% of ionizing radiation in orthopaedic fluoroscopic procedures. There is a higher exposure to the inner thigh during seated procedures. EPDs provided results for individual procedures. PPE currently used by surgeons in orthopaedic trauma theatre adequately reduces radiation exposure to below recommended levels. Normative data per trauma case show specific anatomical areas of higher exposure, which may benefit from enhanced radiation protection. EPDs can be used to assess real-time radiation exposure in orthopaedic surgery. There may be a role in future medical wearables for orthopaedic surgeons.Cite this article: Bone Jt Open2022;3(11):907-912.

Assessment of occupational dose reduction with the use of a floor mounted mobile lead radiation protection shield

With the increasing number and complexity of interventional cardiology procedures, there is the potential for higher occupational radiation doses to the interventionists. In order to reduce the radiation exposure to interventionists, a number of different radiation protection measures can be implemented; the most common of which being personal protective equipment in the form of a lead-equivalent apron. However, significant development has been achieved with mobile lead equivalent radiation protection devices, which provide enhanced radiation protection without the requirement of being directly worn by staff. The RAMPART M1128 radiation protection shield is one of these devices. The dose reduction provided to staff within a Cardiac Catheterisation Laboratory was assessed via the use of electronic personal dosimeters with the Philips live dosimetry system DoseAware (Philips DoseAware). A 60% dose reduction to the primary operator can be achieved with the Rampart device. Further dose reductions are possible for other individuals in the range of 65%–84%. Additionally, dose rate measurements were taken in a simulated clinical set-up using a phantom, which showed that the device provided a 65% dose reduction at eye level and a 90% dose reduction at chest level for the primary operator position. This significant dose reduction means that there is the potential for at least the primary operator to wear a lead apron of reduced lead equivalence specification when the Rampart device is in use, without increasing their occupational exposure and potentially reducing musculoskeletal pain due to the reduced weight.

Radiation dose to nuclear medicine technologists when operating PET/MR compared with PET/CT

Since 2010, positron emission tomography/magnetic resonance (PET/MR) has been increasingly used as clinical routine in nuclear medicine departments. One advantage of PET/MR over PET/computed tomography (CT) is the lower dose of ionising radiation delivered to patients. However, data on the radiation dose delivered to staff operating PET/MR compared with the new generation of PET/CT equipment are still lacking. Our aim was to compare the radiation dose to nuclear medicine technologists performing routine PET/MR and PET/CT in the same department. We retrospectively measured the daily radiation dose received by PET technologists over 13 months by collecting individual dosimetry measurements (from electronic personal dosimeters). Data were analysed taking into account the total number of studies performed with each PET modality (PET/MR with Signa 3T, General Electric Healthcare versus PET/CT with Biograph mCT flow, Siemens), the type of exploration (brain versus whole-body PET), the 18F activity injected per day and per patient as well as the time spent in contact with patients after tracer injection. Our results show a significantly higher whole-body exposure to technologists for PET/MR compared with PET/CT (10.3 ± 3.5 nSv versus 4.7 ± 1.2 nSv per 18F injected MBq, respectively; p < 0.05). This difference was related to prolonged contact with injected patients during patient positioning with the PET/MR device and MR coil placement, especially in whole-body studies. For an equal injected activity, radiation exposure to PET technologists for PET/MR was twice that of PET/CT. To minimise the radiation dose to staff, efforts should be made to optimise patient positioning, even in departments with extensive PET/CT experience.

Modeling, simulation and measurement of radiation exposure using electronic personal dosimeters on realistic and ICRU phantoms

Abstract Exposure studies with voxel phantoms were carried out to understand the new personal dose measurand Hp(10) measured by personal dosimeters under realistic wearing conditions. Two simulated realistic voxel phantoms and the dosimeter assembly are described in a first step. Conditions such as photon fluence, radiation field geometry, and photon energy for simulating the external photon fields at the realistic model are specified. Person-related effective doses are calculated to evaluate the personal dose. The relation between measured deep personal dose and effective dose is demonstrated and discussed by means of the simulated response function of the dosimeters at realistic phantoms.

Status and prospects of electronic personal dosemeters for neutron/photon radiation fields

Abstract For neutron radiation and mixed neutron/photon radiation fields, only a few types of direct reading dosemeters are commercially available or under development. Some important features of these dosemeters are briefly outlined and their energy dependent dose equivalent response and suitability for operational monitoring tasks in nuclear facilities, in particular, are discussed.

Dose rate distribution measuring method using personal dosimeters and localization devices

ABSTRACT To further reduce the radiation exposure of nuclear power plant workers, we propose a new method that enables measurements of radiation distribution. This method uses a worker’s position detection device and an electronic personal dosimeter worn by the worker. The dose rate distribution of γ-rays can be measured with high resolution without increasing the workload of radiation management people. To confirm the feasibility of this concept, a test system was built and measurement tests were conducted in an area where a radiation source was located. The dose rate distribution measurement capability of this system produced results comparable to those predicted by a simulated test, with a difference within 4.0 μSv/h. Moreover, we confirmed the applicability of the proposed method to nuclear power plants on the basis of a rough evaluation for an on-site work situation.

Densitometric analysis of Radiation Absorbed Dose to Patients Undergoing Chest X-ray Examination in a Government Owned Hospital, Kano-Nigeria

Chest X-ray is one the most frequently required diagnostic procedures used in clinical practice to produce an image of organs, tissues and bones of the body with a significant impact on collective dose. However, the radiation dose received by patients from this procedure is likely to show large variations within and among radiodiagnostic centres. This could be traced to be lack of imaging protocols and a lack of local or national diagnostic reference levels. Although the radiation doses resulting from the X-ray procedures are usually measured in terms of effective dose entrance surface dose using electronic personal dosimeter (EPD), pocket dosimeter, thermoluminescent dosimeter (TLD), film badges, and optically stimulated luminescent dosimeter (OSLD). For the sake of radiation protection, densitometric analysis was used to evaluate medical exposure for chest radiographs to determine the radiation doses using a point optical densitometer; PTW-DensiX with a range of 0 to 4.0 optical density. The hospital where this study was carried out is in Kano State. A total of sixty (60) chest radiographic films were collected from the hospital and the optical density of each radiographic film was measured five times at different spots. The mean optical density was obtained and converted by a mathematical relation to absorbed radiation dose in cGy. The results obtained in this study show that the mean absorbed X-ray dose was 0.78 ± 0.13 cGy and is low compared to the previous study held for hospitals in Osun State. Also, when compared with the excess dose of 0.10 Gy recommended by the International Commission on Radiological Protection, it was evident that radiological practice especially as it relates to chest radiographs at the hospital in Kano is within the recommended practice.&#x0D; Keywords: Absorbed dose, Densitometer, Optical Density, Radiation, X-ray

Comparison of calibration factors for field-class dosimeters

This paper presents a comparison performed between two calibration laboratories in several radiation qualities, using dosimeters of varying quality as transfer instruments. The goal of this work was to investigate the viability of using field-class dosimeters for official comparisons and to determine if the calibration factors for field-class dosimeters are comparable between calibration laboratories within the stated measurement uncertainties. The results of the comparison were acceptable for high-quality electronic personal dosimeters in all radiation qualities, and such dosimeters could be used as transfer instruments. On the other hand, comparison results for low-quality dosimeters were often not acceptable, either due to pronounced energy dependence, low stability, or both. Such instruments are unreliable even under well-defined laboratory conditions, and their use in routine measurements may cause doubt in official data or influence public opinion. This problem is often hidden because many dosimeters are calibrated or verified only in 137Cs beams, where the deviations are the smallest. The largest differences are found for low-energy X-ray radiation qualities, where many dosimeters have significant overresponse.

Radiation Protection and Occupational Exposure on 68Ga-PSMA-11-Based Cerenkov Luminescence Imaging Procedures in Robot-Assisted Prostatectomy.

Cerenkov luminescence imaging (CLI) was successfully implemented in the intraoperative context as a form of radioguided cancer surgery, showing promise in the detection of surgical margins during robot-assisted radical prostatectomy. The present study was designed to provide a quantitative description of the occupational radiation exposure of surgery and histopathology personnel from CLI-guided robot-assisted radical prostatectomy after the injection of 68Ga-PSMA-11 in a single-injection PET/CT CLI protocol. Methods: Ten patients with preoperative 68Ga-PSMA-11 administration and intraoperative CLI were included. Patient dose rate was measured before PET/CT (n = 10) and after PET/CT (n = 5) at a 1-m distance for 4 patient regions (head [A], right side [B], left side [C], and feet [D]). Electronic personal dosimetry (EPD) was used for intraoperative occupational exposure (n = 10). Measurements included the first surgical assistant and scrub nurse at the operating table and the CLI imager/surgeon at the robotic console and encompassed the whole duration of surgery and CLI image acquisition. An estimation of the exposure of histopathology personnel was performed by measuring prostate specimens (n = 8) with a germanium detector. Results: The measured dose rate value before PET/CT was 5.3 ± 0.9 (average ± SD) μSv/h. This value corresponds to a patient-specific dose rate constant for positions B and C of 0.047 μSv/h⋅MBq. The average dose rate value after PET/CT was 1.04 ± 1.00 μSv/h. The patient-specific dose rate constant values corresponding to regions A to D were 0.011, 0.026, 0.024, and 0.003 μSv/h⋅MBq, respectively. EPD readings revealed average personal equivalent doses of 9.0 ± 7.1, 3.3 ± 3.9, and 0.7 ± 0.7 μSv for the first surgical assistant, scrub nurse, and CLI imager/surgeon, respectively. The median germanium detector-measured activity of the prostate specimen was 2.96 kBq (interquartile range, 2.23-7.65 kBq). Conclusion: Single-injection 68Ga-PSMA-11 PET/CT CLI procedures are associated with a reasonable occupational exposure level, if kept under 110 procedures per year. Excised prostate specimen radionuclide content was below the exemption level for 68Ga. Dose rate-based calculations provide a robust estimation for EPD measurements.