Electronic Dosimeters Research Articles

Use of Electronic UV Dosimeters in Measuring Personal UV Exposures and Public Health Education

The performance limits of electronic ultraviolet (EUV) dosimeters, which use AlGaN Schottky photodiodes as the ultraviolet radiation (UVR) sensing element to measure personal erythemally weighted UVR exposures, were investigated via a direct comparison with meteorological-grade reference instruments. EUV dosimeters with two types of AlGaN Schottky photodiode were compared to second-generation ‘Robertson–Berger type’ broadband erythemal radiometers. This comparison was done by calculating correction factors for the deviations of the spectral responsivity of each instrument from the CIE erythemal action spectrum and for deviations in their angular response from the ideal cosine response of flat surfaces and human skin. Correction factors were also calculated to convert the output of these instruments to vitamin D-weighted UV irradiances. These comparisons showed that EUV dosimeters can be engineered with spectral responsivities and cosine response errors approaching those of Robertson–Berger type radiometers, making them very acceptable for use in human UVR exposure and sun safety behaviour studies, provided appropriate side-by-side calibrations are performed. Examples of these calibrations and the effect of EUV dosimeter sampling rates on the calculation of received erythemal UVR doses and erythemal UVR dose rates are provided, as well as brief descriptions of their use in primary skin cancer prevention programmes, handheld meters, and public health displays.

Solar ultraviolet radiation exposure among outdoor workers in Alberta, Canada

BackgroundOutdoor workers are at risk of prolonged and high solar ultraviolet radiation (UVR) exposure, which is known to cause skin cancer. The objectives of this study were to characterize the UVR exposure levels of outdoor workers in Alberta, Canada, and to investigate what factors may contribute to their exposure. MethodsThis study collected objective solar UVR measurements from outdoor workers primarily in Alberta during the summer of 2019. Workers were recruited via the management or health and safety teams from building trade unions and employers. Calibrated, electronic UVR dosimeters were worn by workers on their hardhats, wrists, or lapels for five working days. Data on workers’ demographics, jobs, sun protection behaviors, and personal risk factors were collected using questionnaires, and meteorological data for each sampling day were noted. Mean daily exposure measured as the standard erythemal dose (SED) was calculated and compared to the international occupational exposure limit guideline (1.3 SED). Marginal models were developed to evaluate potential determinants of occupational solar UVR exposure. ResultsIn total, 883 measurements were collected from 179 workers. On average, workerswere exposed to 1.93 SED (range: 0.03–16.63 SED) per day. Just under half of workers (45%) were exposed to levels exceeding the international exposure limit guideline. In the bivariate analyses, landscape and maintenance workers, as well as trade and recreation workers, had the highest levels of exposure (average: 2.64 and 1.84 SED, respectively). Regional variations were observed, with the “other” cities/regions (outside of Edmonton and Calgary) experiencing the highest average levels (2.60 SED). Workers who placed the dosimeters on their hardhats experienced higher levels compared to the other groups. Exposure was highest on sunny and mixed days. Education, trade, city, dosimeter placement, forecast, hair colour, and number of hours outside were included in the final exposure model, of which trade, dosimeter placement, forecast, and number of hours outside at work were statistically significant. ConclusionsExposure to elevated solar UVR levels is common among outdoor workers in Alberta. The study findings can help inform future monitoring studies and exposure reduction initiatives aimed at protecting workers.

Cardiac catheterization real-time dynamic radiation dose measurement to estimate lifetime attributable risk of cancer.

Cardiac catheterization procedure is the gold standard to diagnose and treat cardiovascular disease. However, radiation safety and cancer risk remain major concerns. This study aimed to real-time dynamic radiation dose measurement to estimate lifetime attributable risk (LAR) of cancer incidence and mortality in operators. Coronary angiography (CA) with percutaneous coronary intervention (PCI), CA, and others (radiofrequency ablation, pacemaker and defibrillator implantation) procedures with different beam directions, were undertaken on x-ray angiography system. A real-time electronic personal dosimeter (EPD) system was used to measure the radiation dose of staff during all procedures. We followed the Biological Effects of Ionizing Radiation (BEIR) VII report to estimate the LAR of all cancer incidence and mortality. Primary operators received radiation dose in CA with PCI, CA, and others procedures were 59.33 ± 95.03 μSv, 39.81 ± 103.85 μSv, and 21.92 ± 37.04 μSv, respectively. As to the assistant operators were 30.03 ± 55.67 μSv, 14.67 ± 14.88 μSv, and 4 μSv, respectively. LAR of all cancer incidences for staffs aged from 18 to 65 are varied from 0.40% for males to 1.50% for females. LAR of all cancer mortality for staffs aged from 18 to 65 are varied from 0.22% for males to 0.83% for females. Our study provided an easy, real-time and dynamic radiation dose measurement to estimate LAR of cancer for staff during the cardiac catheterization procedures. The LAR for all cancer incidence is about twice that for cancer mortality. Although the radiation doses of staff are lower during each procedure, the increased years of service leads to greater radiation risk to the staff.

A Simulation Study With Electronic Dosimeter to Estimate Patient and Personnel Dose in Orthopedic Surgery

Background: The use of mini C-arm is required in many orthopedic surgeries as an image-guided tool. Studies have shown an unnecessarily high dose to patients if exposures are not properly optimized. Also, scatter radiation to personnel may increase the risk of cancer if an appropriate protective device is not used. Objectives: This study aims to determine the patient’s dose and scatter radiation to the surgeon, anesthetist, and scrub nurse. Also, a comparison will be made with other studies on this topic. Methods: A phantom was designed to simulate a patient on the operating table to produce scatter radiation. In the same vein, a mobile mini C-arm unit was positioned with the x-ray tube beneath the head and the image receptor above the operating table. Measurements were made with a measuring tape from the central axis to the position of the surgeon, anesthetist, and scrub nurse. The Entrance Surface Dose (ESD) was determined by placing the electronic dosimeter at the surface of the phantom to estimate the patient dose. Similarly, each personnel dose/dose rate from the central axis was determined using a similar detector. Results: The total average time for most orthopedic surgeries in the studied facility was 3.3 minutes. The estimated ESD to the patient was 25.03 µSv and the scatter radiation per patient reaching the simulated anesthetist, scrub nurse, and surgeon was, 3.75, 3.59, and 7.72 µSv, respectively. The estimated dose values per year to anesthetist, scrub nurse, and surgeon were 390, 373.36, and 802 µSv, respectively. Conclusion: The personnel recommended limit dose rate was <20000 µSv/y. The technical factor used and total exposure time from this study could have affected the radiation dose. This study showed that personnel was safe even without the use of lead apron. Nevertheless, the use of an appropriate protective device should be encouraged to ensure safety.

Occupational radiation exposure in femoral artery approach is higher than radial artery approach during coronary angiography or percutaneous coronary intervention

Medical radiation exposure is a significant concern for interventional cardiologists (IC). This study was aimed at estimating the radiation exposure of IC operators and assistants in real clinical practice. The radiation exposure of the operator and assistant was evaluated by conducting two types of procedures via coronary angiography (CAG) and percutaneous coronary intervention (PCI) on 1090 patients in 11-cardiovascular centers in Korea. Radiation exposure was measured using an electronic personal dosimeter (EPD). EPD were attached at 3 points on each participant: on the apron on the left anterior chest (A1), under the apron on the sternum (A2), and on the thyroid shield (T). Average radiation exposure (ARE) of operators at A1, A2, and T was 19.219 uSv, 4.398 uSv, and 16.949 uSv during CAG and 68.618 uSv, 15.213 uSv, and 51.197 uSv during PCI, respectively. ARE of assistants at A1, A2, and T was 4.941 uSv, 0.860 uSv, and 5.232 uSv during CAG and 20.517 uSv, 4.455 uSv, and 16.109 uSv during PCI, respectively. AED of operator was 3.4 times greater during PCI than during CAG.

Evaluating the ultraviolet protection factors of urban broadleaf and conifer trees in public spaces

Urban trees provide natural shade and moderate human exposure to solar ultraviolet radiation. To date, most studies quantifying UV attenuation by urban tree canopies have taken place in Australia, with no studies in North America. Few studies have utilized sensors sensitive to UV-B radiation, although the shorter wavelengths are more important in determining erythemal (skin burning) UV. We collected solar UV radiation exposure data beneath 64 individuals of 16 tree species commonly planted in the City of Toronto's schoolyards and public parks, using UV electronic logging dosimeters that have a spectral response closely matching the erythemal action spectrum. Additional data were collected on canopy structure (crown radii, crown transparency, crown depth, diameter at breast height, height to live crown, and leaf-level data). UV protection factor (PF: the ratio of open-site UV to below-canopy UV) varied 2.6-fold among species, ranging from ∼1.3−3.4. Statistical models for variation among trees indicated that crown transparency (%), the ratio of crown breadth to height to live crown, and species shade tolerance were important predictors of PF. Acer platanoides ‘Crimson King’, Celtis occidentalis L., Quercus bicolor Willd., and Fagus sylvatica ‘Purpurea’ showed the highest PF values (>3), and Ginkgo biloba L. and Acer rubrum L. showed the lowest PF values (<2) among sampled species. Findings from this study can help inform tree management strategies and policies to increase UV protection in schoolyards and other public settings.

Time course and local distribution of skin exposure of hand andfingers from [68Ga]Ga-DOTA-NOC synthesis using aself-shieldedmodule.

The study examined the local dose distribution as well as the time course of skin exposure of hand and fingers from [68Ga]Ga-DOTA-NOC synthesis using a self-shielded synthesis module. A compact calibrated electronic dosimeter (ED) with a miniaturized probe was used for real-time measurements of skin dose equivalent Hp (0.07) (reference point: left and right index finger). A time resolved assessment of exposure during radiotracer production was performed. Additionally, thermoluminescence dosimeters (TLD) were used to determine local dose distribution for five different positions (e. g. fingertips). Cumulated Hp (0.07) estimated by ED was analysed and correlated with the measurements obtained by a TLD positioned close to the ED. The cumulative skin exposure from the production process measured by ED, was 74.7 ± 32.7 µSv/GBq and 40.1 ± 14.3 µSv/GBq for the right and left hand, respectively. The exposure recorded by the ED was in the average 19.4 % ± 40.0 % (median = 21.3 %) lower compared to the results from TLD. Highest exposure was recorded during synthesis (guided hand: 24.5 ± 12.2 µSv/GBq) and measuring of product yield including preparation of probes for quality control (guided hand: 36.1 ± 12.7 µSv/GBq). The highest local exposure was measured by a TLD close to the tip of the index finger of the guiding hand (range: 773-1257 µS/GBq). The chosen methodology using ED, proved to be a good concept for identifying procedure steps with an increased exposure level and to determine the time course of skin exposure and to identify procedure steps for further optimization of handling. Furthermore, miniaturized electronic dosimeters may be used for online surveillance of local exposure rates at hands and fingers.

Investigation of using a long-life electronic personal dosimeter for monitoring aviation doses of frequent flyers

For the aim of managing the in-flight cosmic radiation exposure of frequent flyers, we have investigated an application of a recently developed electronic personal dosimeter (D-shuttle) for aviation dosimetry. In four long-haul flights between Japan and Germany, it was confirmed that the D-shuttle values were in the range of 25%–30% of the total H*(10) estimated by a route-dose calculation program JISCARD EX. It was found that the values obtained with D-shuttle on the chest were nearly the same with those in a hand luggage placed under the passenger seat, while the values obtained in a suitcase which was placed in the cargo area were notably lower than those in the cabin. According to these findings, it would be possible to monitor the annual aviation doses of frequent flyers by using the D-shuttle dosimeters kept in a hand luggage. Such continuous measurements will also be useful for verification of an unpredicted additional exposure from solar energetic particles.

Photon energy response optimization using few-channel spectroscopy dose method for Si-PIN photodetector applied in personal dose equivalent measurements

Si-PIN photodetectors having features such as low cost, small size, low weight, low voltage, and low power consumption are widely used as radiation detectors in electronic personal dosimeters (EPDs). The technical parameters of EPDs based on the Si-PIN photodetectors include photon energy response (PER), angular response, inherent error, and dose rate linearity. Among them, PER is a key parameter for evaluation of EPD measurement accuracy. At present, owing to the limitations of volume, power consumption, and EPD cost, the PER is usually corrected by a combination of single-channel counting techniques and filtering material methods. However, the above-mentioned methods have problems such as poor PER and low measurement accuracy. To solve such problems, in this study, a 1024-channel spectrometry system using a Si-PIN photodetector was developed and full-spectrum measurement in the reference radiation fields was conducted for radiation protection. The measurement results using the few-channel spectroscopy dose method showed that the PER could be controlled within ± 14% and ± 2% under the conditions of two and three energy intervals, respectively, with different channel numbers. The PER measured at 0° angle of radiation incidence meets the − 29% to +67% requirements of IEC 61526:2010. Meanwhile, the channel number and counts-to-dose conversion factors formed in the experiment can be integrated into an EPD.

Radiation Doses to Staff in a Hybrid Operating Room: An Anthropomorphic Phantom Study with Active Electronic Dosimeters

To quantify the effects of different imaging settings on radiation exposure to the operator and surgical team in a hybrid operating room (OR). Measurements to determine scatter radiation in different imaging and geometry settings using an anthropomorphic phantom were performed in a hybrid OR equipped with a robotic C arm interventional angiography system (Artis Zeego; Siemens Healthcare, Erlangen, Germany). The radiation dose (RD) was measured with seven calibrated Philips DoseAware active electronic dosimeters and a Raysafe Xi survey detector, which were placed at different locations in the hybrid OR. The evaluated set ups included low dose, medium dose, and high dose fluoroscopy for abdomen; fluoroscopy fade; roadmap; and digital subtraction angiography (DSA), all using 20s exposures. The effect of magnification, tube angulation, field size, source to skin distance, and RADPAD protection shields were assessed. Finally RD during cone beam computed tomography (CBCT) was obtained. In the operator position the initial settings with low dose fluoroscopy caused a RD of 1.03μGy. The use of fluorofade did not increase the radiation dose (1.02μGy), whereas the roadmap increased it threefold (2.84μGy). The RD with "normal fluoro" was 4.13μGy and increased to 6.44μGy when high dose fluoroscopy mode was used. Magnification or field size varying from 42cm to 11cm led the RD to change from 0.86μGy to 2.10μGy. Decreasing the field of view to 25% of the initial size halved the RD (0.48μGy). The RDs for the left anterior oblique 30° and right anterior oblique 30° were 3.26μGy and 1.63μGy, respectively. DSA increased the cumulative dose 33 fold but the RADPAD shield decreased the DSA RD to 4.92μGy. The RD for CBCT was 47.2μGy. Radiation exposure to operator and personnel can be significantly reduced during hybrid procedures with proper radiation protection and dose optimisation. A set of six behavioural rules were established.

Improvement of a spectrum-to-dose conversion function for electronic personal dosimeters

For electronic personal dosimeters (EPDs) based on a spectroscopy system, it is necessary to accurately measure the dose in real-time from the gamma energy spectra. The method of spectrum-to-dose conversion is being used instead of the method of count-to-dose conversion. The G(E) function, a typical method of spectrum-to-dose conversion has been applied to various instruments due to its good dose measurement performance and the advantage of real-time measurements. In this manuscript, we present a method to increase the accuracy of G(E) function for the EPD consisting of a 3 × 3 mm2 PIN diode coupled with a 3 × 3 × 3 mm3 CsI(Tl) scintillator. The new G(E) function was calculated using the adaptive moment estimation (ADAM) method based on Monte Carlo simulation. The proposed G(E) function is verified by comparison with the least-square method (LSM), which is the conventional method for calculating the G(E) function and with the gradient-descent method (GDM), which is the basis for the ADAM. The relative difference was acquired to compare the converted dose value using each G(E) function by using 241Am, 57Co, 22Na, 137Cs, 54Mn and 60Co radioisotopes. In addition, the energy response to 137Cs of each G(E) function was obtained. The relative difference of G(E) function according to LSM, GDM, and ADAM was in the range of ±28.54, ±12.59, and ±9.9%, respectively, and the energy response to 137Cs was 0.71 to 1, 0.87 to 1.02, and 0.9 to 1.03, respectively.

A Radon Background-subtraction Algorithm for Electronic Personal Dosimeters.

Many first responders are outfitted with electronic personal dosimeters to recognize and be alerted to radiological hazards during their response operations. These dosimeters provide invaluable measurement data for force protection, allowing the first responder to assess a response situation and take protective measures for themselves and other individuals involved based on instrument readings of dose rate or cumulative dose. However, capabilities of common electronic personal dosimeters to identify and distinguish various contributions to the instrument reading, in particular from natural radiological sources, are rather limited. An algorithm has been developed for two-channel electronic personal dosimeters that quantifies the signal contribution from radon progeny and allows for background subtraction from radon and radon progeny in the instrument reading. This algorithm will be particularly useful in operational scenarios where first responders may be subject to rapidly changing levels of natural background radiation, which could mimic the presence of anthropogenic sources of ionizing radiation.

First steps towards online personal dosimetry using computational methods in interventional radiology: Operator's position tracking and simulation input generation

Interventional radiologists/cardiologists are repeatedly exposed to low radiation doses which makes them the group of the highest occupational exposure and put them at high risk of stochastic effects. Routine monitoring of staff is usually performed by means of passive dosimeters. However, current personal dosimeters are subject to large uncertainties, especially in non-homogeneous fields, like those found in interventional cardiology (IC). Within the PODIUM (Personal Online DosImetry Using computational Methods) research project, a user-friendly tool was developed based on MCNP code to calculate doses to the staff in IC. The application uses both the data of motion tracking system to generate the position of the operator and the data from the Radiation Dose Structure Report (RDSR) from the imaging device to generate time-dependent parameters of the radiation source. The results of the first clinical validation of the system show a difference of about 50% between simulated Hp(10) with MCNP and measured Hp(10) with electronic personal dosimeter worn above the lead apron.

A TECHNOLOGY OVERVIEW OF ACTIVE IONIZING RADIATION DOSEMETERS FOR PHOTON FIELDS.

Radiation protection and radiation dosimetry strongly rely on measurements performed by dosimetry instrumentation. Two categories of dosimetry instrumentation prevail: personal dosemeters and survey meters. Passive dosemeters were for many years the base of personal and area dosimetry (environmental, including workplace). Survey meters have been long-established between area meters due to their dose rate measurement capability, but just over a decade ago, debates over possibility that electronic personal dosemeters (EPDs) could replace passive personal dosemeters as legal monitoring devices have started. These debates have now branched into the use of EPDs, but also survey meters in various exposure scenarios, where some concerns have been reported. These concerns were mostly related to the response in pulsed X-ray fields and poor energy response. This article summarizes recent literature related to electronic dosemeters for strongly penetrating photon radiation and covers technologies used in contemporary EPDs and survey meters, their performance and future perspectives.

Robotic Dispersal Technique for 35 GBq of 140La in an L-polygon Pattern.

In 2018, Defence Research and Development Canada, in partnership with Natural Resources Canada, led a field trial of survey and mapping of a large dispersion of radioactivity using Unmanned Aerial Vehicles (UAVs). The intent was to disperse La material in a 3,200 m L-polygon with an approximate activity level of 10 MBq m and to measure the radioactive material using sensors carried by UAVs. Due to the potential radiological hazard to personnel, the activity was approved only if Unmanned Ground Vehicles (UGVs) were able to completely handle and disperse the material remotely. One UGV was equipped with a traditional agricultural sprayer to disperse the material, and one UGV was equipped with a force feedback manipulator arm. Due to the freezing temperatures during dispersal, the 35 GBq of La was dispersed non-uniformly as one sprayer boom failed to perform as tested. However, rough analysis of the electronic dosimetry on the UGV concluded that 99% of the material was dispersed on the ground. The dosimeter placed closest to the robot manipulator arm, used for dispersal of material, indicated a contact dose of 33.5 mSv. The electronic dosimeter placed where the driver would have sat on the sprayer vehicle if it were not unmanned indicated a dose of 22.3 mSv. Thus, the use of UGVs for material dispersion substantially reduced the external exposure to personnel. The use of UGVs eliminated the potential of internal exposure as well. The Radiation Safety Officer received the highest dose at approximately 3 μSv, with the majority of the exposure coming from the handling of the Type A container.

Characterization of personal solar ultraviolet radiation exposure using detrended fluctuation analysis

Studies of personal solar ultraviolet radiation (pUVR) exposure are important to identify populations at-risk of excess and insufficient exposure given the negative and positive health impacts, respectively, of time spent in the sun. Electronic UVR dosimeters measure personal solar UVR exposure at high frequency intervals generating large datasets. Sophisticated methods are needed to analyze these data. Previously, wavelet transform (WT) analysis was applied to high-frequency personal recordings collected by electronic UVR dosimeters. Those findings showed scaling behavior in the datasets that changed from uncorrelated to long-range correlated with increasing duration of time spent in the sun. We hypothesized that the WT slope would be influenced by the duration of time that a person spends in continuum outside. In this study, we address this hypothesis by using an experimental study approach. We aimed to corroborate this hypothesis and to characterize the extent and nature of influence time a person spends outside has on the shape of statistical functions that we used to analyze individual UVR exposure patterns. Detrended fluctuation analysis (DFA) was applied to personal sun exposure data. We analyzed sun exposure recordings from skiers (on snow) and hikers in Europe, golfers in New Zealand and outdoor workers in South Africa. Results confirmed validity of the DFA superposition rule for assessment of pUVR data and showed that pUVR scaling is determined by personal patterns of exposure on lower scales. We also showed that this dominance ends at the range of time scales comparable to the maximal duration of continuous exposure to solar UVR during the day; in this way the superposition rule can be used to quantify behavioral patterns, particularly accurate if it is determined on WT curves. These findings confirm a novel way in which large datasets of personal UVR data may be analyzed to inform messaging regarding safe sun exposure for human health.

Staff Doses and Patient Skin Doses in Hybrid Operating Room Procedures – An Anthropomorphic Phantom Study with Active Electronic Dosimeters

Introduction - Fluoroscopically guided hybrid procedures have rapidly increased among vascular surgeons. During these interventions, the personnel are at risk of stochastic or deterministic effect of ionizing radiation. Minimizing the absorbed radiation dose is essential to reduce its harmful effects for the patients and personnel. The aim of our study was to quantify the effects of different imaging settings on the staff dose and patient skin dose with the active electronic dosimeters (AED). Methods - Measurements to determine radiation dose in different imaging and geometry settings were performed in a hybrid operation room (OR) equipped with a robotic C-arm interventional angiography system (Artis Zeego, Siemens Healthcare) with an anthropomorphic adult female phantom (ATOM 702-D, CIRS). Scattered radiation doses were measured with nine calibrated Philips DoseAware AEDs and a Raysafe Xi survey detector (Unfors Raysafe) that were placed at different locations in the OR mimicking the positions of surgeons and nurses during the procedure (Figure 1). Furthermore, a Raysafe R/F detector was placed under the phantom in the primary beam to measure the entrance surface air kerma. The evaluated imaging set-ups contained low-dose, medium-dose, and high-dose fluoroscopy for abdomen, low-dose DSA for abdomen, fluorofade, roadmap, and dyna-CT. The effect of magnification was evaluated with five magnification levels, tube angulation with ±30° settings, and field size, and source-to-skin distance with a few set-ups. We also determined the effects of RADPAD radiation protection shields (Worldwide Innovations and Technologies) on staff doses. Radiation was on for 20 seconds in all the imaging set-ups, except for Dyna-CT. The results are expressed as relative doses (RD) compared to the cumulative dose (1.05 μSv) measured with the AED B (“operating surgeon”) in the reference imaging setting with abdomen low-dose fluoroscopy program (4 pps) and C-arm in posterior-anterior position without magnification. Results - The use of fluorofade did not increase the cumulative dose (RD=1.1) whereas the roadmap increased it threefold (RD=3.1). The RD was 4.5 with normal-fluoro 7.5 pps instead of 4 pps and 7.0 when high-dose-fluoro was used 7.5 pps. The RDs for the magnifications 2,3,4 and 5 were 0.9, 1.0, 2.0, and 2.3 respectively. Decreasing the field-of-view to 25% of the reference field-of-view halved the radiation dose (RD=0.52). The RDs for the LAO 30° and RAO 30° were 1.6 and 2.1, respectively. The RADPAD shield decreased the cumulative dose to fifth (RD=0.23). DSA increased the cumulative dose 33-fold but the RADPAD shield decreased the DSA RD to 6.6. The RD for Dyna CT was 79. The patient skin dose in the reference setting was 229 μGy whereas 58-fold with the DSA. The doses in the AED D (“assisting nurse) were unmeasurable due to low dose in most of the set-ups. The AED F gained 4-fold doses compared to the AED E as the protection shields were on the right side of the table. Conclusion - Radiation exposure to personnel, as well as to the patients, can significantly be reduced in the hybrid OR procedures with optimization. For this purpose, the AEDs offer excellent tools.

OCCUPATIONAL RADIATION DOSE PERFORMING HEPATOBILIARY MINIMALLY INVASIVE PROCEDURES IN CHILDREN WEIGHING LESS THAN 20kg.

Our objective is to retrospectively evaluate the effective dose (E) of operators performing pediatric Hepatobiliary Minimally Invasive Procedures (HMIP). Between October 2015 and December 2017, 58 consecutive HMIP were performed on 26 children weighing less than 20kg (mean 12.3kg, median 13kg, range 2.4-20kg). About 31 vascular procedures (n=9 hepatic venograms with/without stenting; n=9 retrograde wedge portography; n=8 transhepatic portography with angioplasty and/or stenting and n=5 hepatic arteriography/embolization) and 27 non-vascular procedures (n=6 percutaneous transhepatic biliary drainage (PTBD); n=3 bilioplasty; n=15 biliary catheter change and n=3 cholangiogram) were performed. Electronic personal dosimeters were used to measure radiation doses to the interventional radiologist, radiographer and anesthesia nurse. The results shows the highest mean effective dose: interventional radiologist's in PTBD (1.18μSv); radiographer's in hepatic veins phlebography with/without stenting (0.25μSv) and nurse's in hepatic arteriography/embolization (0.26μSv). Operators' E can vary depending on the complexity of procedure performed and the position of the operators within the angiosuite.

Reprint of “Occupational exposure in nuclear medicine and interventional cardiology departments in Sudan: Are they following radiation protection standards?”

Monitoring of staff's radiation exposure in medicine is an important radiation protection task. This study aimed to measure the staff doses in the nuclear medicine (NM) and interventional cardiology (IC) departments in Sudan and assess whether the measured doses fall within the recommended radiation protection standards. 37 members of staff involved in the NM and IC procedures were monitored using electronic personal dosimeters (EPDs). In IC, the average monthly Hp (10) values ranged from 30.0 to 38.9 µSv (to cardiologists), from 3.6 to 13.5 µSv (to nurses), and from 3.5 to 8.9 µSv (to technologists). The annual effective dose ranged from 1.95 to 2.53 mSv (to cardiologists), from 0.23 to 0.88 mSv (to nurses), and from 0.23 to 0.56 mSv (to technologists). In NM, the monthly Hp (10) values ranged between 83.0 and 84.0 µSv (to nurses), 38.8 and 54.0 µSv (to pharmacists), 16.9 and 70.2 µSv (to technologists), 40.2 and 76.6 µSv (to physicists). The annual effective doses ranged from 0.91 to 0.92 mSv (to nurses), 0.43–0.59 mSv (to pharmacists), 0.19–0.77 mSv (to technologists), and 0.44–0.84 mSv (to physicists). The estimated doses fall below the recommended annual dose limit. However, the lack of a radiation surveillance program and use of occupational exposure control tools are of concern in both the IC and NM departments.

Relative response of dosimeters to variations in scattered X-ray energy spectra encountered in interventional radiology

PurposeThe new lower eye lens dose limit is of relevance in interventional radiology, where higher dose procedures result in increased scattered radiation to staff. The eye lens dose may be monitored using the directional dose equivalent at 3 mm depth, Hp(3), or through Hp(10) or Hp(0.07) measurements and using conversion factors. However, there are a considerable range of factors which contribute to measurement uncertainties, one of which is the incident photon energy. This study investigated the energy spectra of scattered radiation in interventional radiology, and the dosimetry accuracy of dosimeter types, evaluating their energy dependence. MethodsScatter X-ray energy spectra were recorded under varied conditions in a fluoroscopy imaging suite. Dosimetry accuracy of eye dosimeters, including TLDs (100 s, 100Hs), Landauer Hp(3), John Caunt ED3 and Electronic Personal dosimeters (EPDs) were compared to air kerma measurements across a range of tube voltages. ResultsThe variation of energy spectra with changing phantom thickness, spectrometer angulation and filtration are presented. The 100 and 100H TLDs, and EPDs showed a consistent air kerma response (within 10%) with changes in energy. The real-time silicon diode detectors showed a variable over response of between 10 and 25% across the energies investigated while Landauers dedicated Hp(3) eye dosimeters showed considerable variation between dosimeters for similar conditions, a 17% variation at 50 kVp. ConclusionThe work aimed to validate the scattered energy spectra typically encountered in interventional radiology and to further determine the accuracy of eye dosimeters in relation to energy response variations.