Body Dosimeters Research Articles

Minimizing operator exposure: field data analysis of three closed transfer systems for pesticide mixing and loading

Three Closed Transfer Systems (CTS) were evaluated for their reduction of operator exposure to plant protection products during mixing and loading: the inverted extraction systems, easyFlow M and easyconnect, and the probe extraction system, GoatThroat®. Exposure data were generated for gloves, hands, head, inner and outer body dosimeters generated in 4 European countries for high rate (Sorbitol) and low rate (Xylitol) surrogate products used by 12 operators. Exposure values were compared with predicted data using the Agricultural Operator Exposure Model as a benchmark for open pour loading (used in the EFSA Guidance). The CTS types conformed with the ISO 21191 standard for CTS performance, and their potential to significantly reduce operator exposure was confirmed in this study. There was no statistical difference in potential (naked) or actual (one layer of clothing) operator exposure using both inverted CTS types; allowing these data to be pooled. The inverted CTS types resulted in higher mean protection (> 98% potential exposure and > 95% actual exposure) than GoatThroat® (> 80% potential exposure and > 95% actual exposure). These data can be used to derive reduction factors that could be used in the AOEM model for calculations involving mitigation e.g., 0.05 for inverted CTS since they reduced exposure by > 95% and 0.3 for probe extraction CTS types. All 3 CTS significantly reduced operator exposure to products during M&L. These and future CTS types which comply with ISO 21191 standards could be considered as mitigation devices. These findings will help to build confidence of farmers to use CTS routinely, resulting in safer pesticide handling.

Evaluation of exposure to ionizing radiation of medical staff performing procedures with glucose labeled with radioactive fluorine - 18F-FDG

Employees of nuclear medicine facilities performing medical procedures with the use of open radioactive sources require continuous detailed control of exposure to ionizing radiation.Thermoluminescent (TL) detectors placed in dosimeters: for the whole body, for lenses, ring and wrist dosimeters were used to assess exposure.The highest whole-body exposure of (1.70 ± 1.09) μSv/GBq was recorded in nurses administering radiopharmaceutical to patients. The highest exposure to lenses and fingers was recorded for employees of the quality control zone and it was (8.08 ± 2.84) μSv/GBq and a maximum of (1261.46 ± 338.93) μSv/GBq, respectively. Workers in the production zone received the highest doses on their hands, i.e. (175.67 ± 13.25) μSv/GBq.The measurements performed showed that the analyzed workers may be classified as exposure category A. Wrist dosimeters are not recommended for use in isotope laboratories due to underestimation of ionizing radiation doses. Appropriately selected shields, which significantly reduce the dose received by employees, must be used in isotope laboratories. Periodic measurements confirmed that the appropriate optimization of exposure reduces the radiation doses received by employees.

Insights into handling and delivery of Y-90 radioembolization therapies.

The use of Y-90 radioembolization techniques has become a standard tool for the treatment of liver cancer and metastatic diseases that result in liver lesions. As there are only two approved forms of radioembolization therapy, the procedures for use are also fairly standardized even though exact international and interdepartmental procedures can vary. What has been less published over the years are the nuanced differences in delivery techniques and handling of the two available Y90 radioembolization therapies. This paper seeks to examine various aspects of delivery techniques, product handling, and radiation exposure that differ between the available and approved products. Understanding these differences can assist with providing more efficient treatment, confirmation of accurate therapy, more informed handling of the products, and improved training of physicians and other hospital staff. Two commercially available and approved radioembolization devices were compared to assess nuanced, but key differences between the available products regarding therapy delivery, handling of the products, and radiation exposure to patients and staff. This work is broken into two sections: (1) Therapy Delivery, (2) Radiation Safety. Therapy delivery characteristics were assessed by using an external radiation detector system with detectors placed inside of each delivery system facing the dose vial and on the output catheter lines to the patient. Additional detectors were placed near the liver of the patient and on top of the foot to measure extremities. Data were acquired continuously throughout therapy delivery to collect time activity curves (TACs) for the characterization of each therapy. These data were analyzed to assess if (a) real-time monitoring of radiation could be used to provide an accurate assessment of residual dose before the patient leaves the procedure room, and (b) can dose delivery characteristics be observed that enable improved training and quality control. Calculation of residual dose using the external detector TACs was performed by analyzing initial and final activity peaks to determine measured count rate differences. Radiation safety aspects were assessed by monitoring radiation exposure to staff handling each of the available therapy products. Nuclear medicine technologists and interventional radiology physician body and hand doses were measured for each delivered therapy using standard body and ring dosimeters. The TACs noted above collected for the liver and extremities were used to assess if any off-target or leached Y90 activity could be detected for each therapy. Blood was collected at times before, during, and after treatment and then counted on a gamma counter to assess differences in free Y90 circulating in the blood. Each patient in this study also received a post-treatment whole-body PET/CT at 2-4 h post-infusion to assess for any aggregate free Y90 deposition that may have resulted from circulating free Y90 in the subject following therapy. Calculations of residual dose in the vial following therapy using the real-time detection methods resulted in values that were not statistically different from the values calculated by nuclear medicine following the procedure ( ). Real-time collection of dose delivery data enabled observation of key characteristics related to each delivery method. For SIR-spheres procedures, the cycle of pushing the dose and visualizing with fluoro can easily be seen with each push resulting in a smaller and smaller peak with intermittent fluoroscopy pulses. TheraSpheres infusions show a rapid bolus with nearly all of the measurable injected activity being infused in the first push of the dose. Staff radiation exposure assessments showed statistically significant differences between glass and resin spheres for hand doses of physicians and technologists (p > 0.05), but no statistical difference between body doses for both products ( ). Assessments of free Y90 circulating during therapy showed that patients undergoing therapies with resin spheres had post-infusion blood levels that were 120% higher than pre-infusion levels while glass sphere therapy patients only saw a 7% rise in post-infusion blood levels. The coefficients of variation (COVs) across glass sphere measurements pre, during, and post, were only 0.008 while resin sphere measures saw much greater variability with a COV of 0.45. Both glass and resin therapies showed blood levels at 2-4 h post-injection to be similar to levels measured pre-injection. Neither therapy showed any signs of focal aggregation at 2-4 h post-infusion on whole-body PET/CT. Although glass and resin radioembolization therapies are similar, they both have unique characteristics related to their administration and handling by staff. Understanding the nuances can assist in providing more efficient delivery, better staff education, and reducing radiation exposure to everyone involved with these therapies. The use of near real-time monitoring is feasible and can be used to obtain critical information about the delivery success of a therapy and can inform physicians on their techniques to optimize their practice as well as provide more consistent training to residents.

Determination of a reliable assessment for occupational eye lens dose in nuclear medicine.

The most recent statement published by the International Commission on Radiological Protection describes a reduction in the maximum allowable occupational eye lens dose from 150 to 20 mSv/year (averaged over 5‐year periods). Exposing the eye lens to radiation is a concern for nuclear medicine staff who handle radionuclide tracers with various levels of photon energy. This study aimed to define the optimal dosimeter and means of measuring the amount of exposure to which the eye lens is exposed during a routine nuclear medicine practice. A RANDO human phantom attached to Glass Badge and Luminess Badge for body or neck, DOSIRIS and VISION for eyes, and nanoDot for body, neck, and eyes was exposed to 99mTc, 123I, and 18F radionuclides. Sealed syringe sources of each radionuclide were positioned 30 cm from the abdomen of the phantom. Estimated exposure based on measurement conditions (i.e., air kerma rate constants, conversion coefficient, distance, activity, and exposure time) was compared measured dose equivalent of each dosimeter. Differences in body, neck, and eye lens dosimeters were statistically analyzed. The 10‐mm dose equivalent significantly differed between the Glass Badge and Luminess Badge for the neck, but these were almost equivalent at the body. The 0.07‐mm dose equivalent for the nanoDot dosimeters was greatly overestimated compared to the estimated exposure of 99mTc and 123I radionuclides. Measured dose equivalents of exposure significantly differed between the body and eye lens dosimeters with respect to 18F. Although accurately measuring radiation exposure to the eye lenses of nuclear medicine staff is conventionally monitored using dosimeters worn on the chest or abdomen, eye lens dosimeters that provide a 3‐mm dose equivalent near the eye would be a more reliable means of assessing radiation doses in the mixed radiation environment of nuclear medicine.

Radiation Dose to the Eye Lens Through Radiological Imaging Procedures at the Surgical Workplace During Trauma Surgery.

Background: Due to the drastic reduction of the eye lens dose limit from 150 mSv per year to 20 mSv per year since 2018, the prospective investigation of the estimated dose of the eye lens by radiological imaging procedures at the surgical site during trauma surgery in the daily work process was carried out. This was also necessary because, as experience shows, with changes in surgical techniques, there are also changes in the use of radiological procedures, and thus an up-to-date inventory can provide valuable information for the assessment of occupationally induced radiation exposure of surgical personnel under the current conditions. Methods: The eye lens radiation exposure was measured over three months for five trauma surgeons, four hand surgeons and four surgical assistants with personalized LPS-TLD-TD 07 partial body dosimeters Hp (0.07). A reference dosimeter was deposited at the surgery changing room. The dosimeters were sent to the LPS (Landesanstalt für Personendosimetrie und Strahlenschutzausbildung) measuring institute (National Institute for Personal Dosimetry and Radiation Protection Training, Berlin) for evaluation after 3 months. The duration of the operation, occupation (assistant, surgeon, etc.), type of surgery (procedure, diagnosis), designation of the X-ray unit, total duration of radiation exposure per operation and dose area product per operation were recorded. Results: Both the evaluation of the dosimeters by the trauma surgeons and the evaluation of the dosimeters by the hand surgeons and the surgical assistants revealed no significant radiation exposure of the eye lens in comparison to the respective measured reference dosimeters. Conclusions: Despite the drastic reduction of the eye lens dose limit from 150 mSv per year to 20 mSv per year, the limit for orthopedic, trauma and hand surgery operations is well below the limit in this setting.

Étude dosimétrique de préparations de médicaments radiopharmaceutiques au 68Ga

AimProduction of 68Ga-radiopharmaceuticals is a rapidly growing field in France. However, operators may already be involved in other radiopharmaceutical activities. It is thus necessary to know the exposure of this new activity. Material and methodsFor passive dosimetry, a radiophotoluminescent (RPL) dosimeter, a thermoluminescent (TLD) chip, 2 TLD rings and a passive dosimeter for crystalline were used. For active dosimetry, an extremity dosimeter and a whole body dosimeter were used. This study was performed during semi-automatized production of 68Ga-investigational medicinal products. Values were normalized to 500MBq manipulated (median activity using a 1850MBq 68Ga-generator), 60 radiosynthesis (maximum enrollment ability of our center) and 2 operators. A LB123 proportional counter was used for quantification of external exposition to 10MBq 68Ge and internal exposition by inhalation was theoretically assessed. 68Ga emission attenuation by collective protection equipments was also discussed. ResultsConsidering passive dosimetry, the equivalent dose to extremities was 21.75±0.34mSv, the whole-body effective dose was 0.189±0.011mSv and the dose to crystalline was 0.925±0.009mSv. Considering active dosimetry, the equivalent dose to extremities was 8,75±0.12mSv and the whole-body effective dose was 0,088±0.009mSv. Total exposure to 68Ge was 1.75μSv. ConclusionIn our hands, 68Ga is a directly transposable activity in radiopharmacies already equipped for 18F because of a dosimetry complying with regulatory limits and suitable radiation protection of collective equipments.

Demonstrating Compliance With Proposed Reduced Lens of Eye Dose Limits in Nuclear Medicine Settings.

Based on ongoing research on ionizing radiation thresholds for cataracts, the International Commission on Radiological Protection has proposed new guidelines lowering the annual occupational lens of eye dose limit from 150 mSv to 20 mSv. The International Atomic Energy Agency has operationalized these new guidelines. Subsequently, national/regional radiation protection regulators are reviewing their lens of eye dose limits with an aim of moving towards the proposed new limits, resulting in licensees having to demonstrate compliance. In health care settings, fluoroscopic interventional practices generally have higher lens of eye doses and nuclear medicine settings generally have lower doses. A prospective cohort (n = 19) of nuclear medicine technologists wore dedicated lens of eye dosimeters for a 3 mo period synchronized with their body dosimeter schedules. The lens of eye dosimeters were validated to have a linear response in the anticipated dose ranges. The participants worked in a relatively high-volume nuclear medicine practice, which included general and cardiac, positron emission tomography/computed tomography, radiopharmacy, and cyclotron operations. The annualized dose ranges were 0.0-3.68 mSv (lens of eye) and 0.48-4.72 mSv (whole body). There was a good correlation between lens of eye and body dosimeter readings (R = 0.67). There were no significant differences in lens of eye dose by work type, worker sex, or side on which the dosimeter was worn. The findings should be generalizable to other similar practices, especially in North America, and should be sufficient to demonstrate regulatory compliance in nuclear medicine settings with the proposed new lens of eye dose limits.

Eye lens dose monitoring in the UK nuclear industry using active personal dosemeters

The reduction of the dose limit for eye lens from 150 to 20 mSv yr−1 must be implemented by EU member states by February 2018. Consequently, there is a requirement for all employers engaged with work with ionising radiation to have appropriate monitoring arrangements in place by this date to demonstrate that they can meet this new limit for all workers. Eye lens dose is conventionally monitored by specific dosemeters worn near the eye. However, it is usually impractical for these dosemeters to be worn at all times in the workplace which can lead to problems accounting for any periods of work when an eye lens dosemeter has not been worn. The Berkeley Approved Dosimetry Service provides a monitoring service for 22 nuclear sites in the UK using active personal dosemeters (APDs) for measuring Hp(10) and Hp(0.07). TLDs for extremity and eye are also issued as appropriate for the working conditions. An analysis of the data from 2007 to 2016 concludes that the values for Hp(0.07) as monitored indirectly by APDs worn on the trunk are comparable to the values assessed by specific Hp(3) eye TLDs. This paper sets out evidence that compliance with the 20 mSv dose limit for the eye lens can be demonstrated using routine issue APDs although specific eye TLDs may still be required to meet international guidance for non-uniform workplace fields. This evidence supports the recent statement from International Radiation Protection Association that ‘for the nuclear industry and other non-medical sectors the use of a whole body dosimeter is considered likely to be sufficient for the majority of workers’.

Utilizing Monte Carlo simulations in estimation of occupational eye lens dose based on whole body dosemeter in interventional cardiology and radiology

Medical staff performing interventional procedures in cardiology and radiology is considered to be a professional group exposed to high doses of ionizing radiation. With new epidemiological evidences and recently reduced eye lens dose limit, dose assessment to the lens of the eye, in the interventional cardiology, has become one of the most challenging research topics. This paper presents results of the eye lens dose assessment in interventional cardiology obtained by means of the computational dosimetry. Since placing and wearing the dedicated eye lens dosimeter is encumbering for the staff, Monte Carlo simulation provides an accurate and efficient method for obtaining an indication of doses to the eye lenses. Eye lens doses were estimated for three typical beam projections (PA, LAO, and RAO) and tube voltages ranging from 80 kV to 110 kV, with different protective equipment setups, for the first operator position. Simulations were carried out using MCNPX code. Results revealed that a whole body dosimeter worn at the thyroid center position gives the best estimate of the eye lens dose with a spread from 11 % to 18 % for the left eye. Corresponding average conversion coefficient from whole body to the eye lens dose is estimated to be 0.18.

Abstract ID: 73 Design of a personal dosimeter for estimating the effective dose of medical staff when wearing radioprotective garments using Monte Carlo simulations

Medical staff performing X-ray-guided interventional procedures is exposed to scattered ionizing radiation. Radioprotective garments (RPG) are usually worn as personal radiation protection equipment. Different methodologies have been proposed to estimate the effective dose when RPG are used ( E RPG ) , like applying a correction factor to the dose of a standard H p (10) dosimeter worn above or below RPG (single dosimetry), or the use of an algorithm combining the dose from two of them: one worn above RPG and the other one worn below (double dosimetry). But even with these methodologies it remains difficult to provide a good estimate of the effective dose ( i . e . a conservative estimate with minimized overestimation) under all possible exposure conditions [1] . This study aimed at designing a personal whole body dosimeter capable of estimating E RPG directly (without the intermediate step of H p (10)) by means of Monte Carlo calculations using MCNPX2.7.0. The ICRP110 reference male phantom was equipped with a mathematically-defined 0.5 mm-thick lead apron and collar and its effective dose ( E RPG ) was calculated for photon beams with energies in the range of interest in interventional procedures (20–120 keV) and angles of incidence (−60° to +60°) parallel to the transverse plane of the body. The design of the new dosimeter should be such that its energy and angular response is as similar as possible to that of the calculated E RPG . The following design parameters have been considered in the simulations: material composition, thickness and geometry of elements around the detector and type of dosimetric detectors. Current status of the design process and some of the steps needed to reach this status are presented. The photon energy and angular dependences are shown for two dosimeter models consisting of two radiosensitive detectors with different filtration: a simplified model based on thermoluminescent detectors and a more realistic model based on glass radiophotoluminescent detectors. For both dosimeters the energy and angular dependence of the combined dose from the two detectors is usually within ± 20% of the calculated effective dose E RPG .

Radiation exposure of cardiac sonographers working in an academic noninvasive cardiovascular imaging laboratory.

Exposure to workplace radiation among cardiac sonographers has been felt to be low, and patient-related sources have been considered negligible. Sonographers may be exposed to radiation from patient emitted sources as well as external sources in interventional laboratories. This study quantified radiation exposure to cardiac sonographers. Cardiac sonographers, vascular imaging technologists, exercise physiologists, noninvasive nursing staff, and CT/MRI technologists were provided body dosimeter badges. Sonographers were provided dosimeter rings for their scanning hands. Radiation exposure was quantified from the dosimeter data, reported in millirems (mrem) for deep, eye, and shallow exposure, as well as shallow exposure data from the rings. Data were prospectively collected for 63 employees over a 12-month period and retrospectively analyzed. The mean annual deep body exposure in sonographers was 8.2mrem/year, shallow exposure 9.8mrem/year, eye exposure 8.5mrem/year, and ring exposure 207mrem/year. There was a significant difference between body and ring exposure (P=.0002). When comparing exposure data between the vascular imaging technologists, CT/MRI technologists, noninvasive nursing staff, and the cardiac sonographers, there were no statistical differences (P>.23). Exercise physiologists had significantly higher exposure compared to sonographers (P<.03). This single-center experience demonstrates that, while exposure is low, cardiac sonographers are exposed to workplace radiation, most likely from patient emitted radiation. The finding that radiation exposure from rings exceeded body exposure supports this conclusion. Continued education and assessment of work flow practices should be employed to minimize staff radiation exposure.

Editorial: ERCP-Related Radiation Cataractogenesis: Is It Time to Be Concerned?

With the growing number of fluoroscopic guided endoscopic procedures, radiation-related risk needs to be further assessed. Recent evidence indicates that radiation cataractogenesis occurs at a lower dose threshold than previously believed. While body aprons and thyroid shields are well-established standard protection during fluoroscopy, ocular safety and the use of protective eyewear are not as well defined. This prospective study answered two important questions: Does the standard body dosimeter provide an accurate ocular dosimetry? And what is the time of fluoroscopy needed to warrant using lens protection? It also raises the question whether current guidelines need to be updated.

Ocular Radiation Threshold Projection Based off of Fluoroscopy Time During ERCP.

Current international guidelines for ocular radiation exposure suggest a threshold of 20 millisieverts (mSv)/year. Although endoscopists wear lead aprons, use of protective eye wear is optional. This study was conducted to analyze the lens radiation exposure during endoscopic retrograde cholangiopancreatography (ERCP) for endoscopists to determine the time of fluoroscopy needed to warrant using lens protection during ERCP. ERCP patients were prospectively enrolled. Indications, interventions, fluoroscopy time, dose, and attending ± fellow involvement were recorded. Radiation exposure was collected from body dosimeters and dosimeters placed between the eyes. Cumulative radiation doses were obtained at study completion and averaged over the total fluoroscopy time to determine the mSv/hour exposure. A total of 187 cases were included. Attendings and fellows wore lens dosimeters in 178 and 126 cases, respectively, and body dosimeters in 174 and 128 cases, respectively. Attendings and fellows wore lens dosimeters throughout 15.89 and 11.24 h of fluoroscopy, respectively. The cumulative radiation dose absorbed per lens dosimeters was 5.35 mSv for attendings and 2.55 mSv for fellows. The projected lens absorption by the body dosimeters was 19.03 mSv for attendings and 5.21 mSv for fellows. The hourly fluoroscopy lens exposure was 0.34 mSv/hour for attendings and 0.23 mSv/hour for fellows. The amount of fluoroscopy hours needed to reach the currently suggested lens threshold limit (20 mSv/year) was 59.41 h for attendings and 88.17 h for fellows. Radioprotective eye wear should be worn by physicians with yearly fluoroscopy times in similarly structured practices that meet or exceed these thresholds.

Validation of ELDO approaches for retrospective assessment of cumulative eye lens doses of interventional cardiologists—results from DoReMi project

The first validation results of the two approaches developed in the ELDO project for retrospective assessment of eye lens doses for interventional cardiologists (ICs) are presented in this paper. The first approach (a) is based on both the readings from the routine whole body dosimeter worn above the lead apron and procedure-dependent conversion coefficients, while the second approach (b) is based on detailed information related to the occupational exposure history of the ICs declared in a questionnaire and eye lens dose records obtained from the relevant literature. The latter approach makes use of various published eye lens doses per procedure as well as the appropriate correction factors which account for the use of radiation protective tools designed to protect the eye lens. To validate both methodologies, comprehensive measurements were performed in several Polish clinics among recruited physicians. Two dosimeters measuring whole body and eye lens doses were worn by every physician for at least two months. The estimated cumulative eye lens doses, calculated from both approaches, were then compared against the measured eye lens dose value for every physician separately.Both approaches results in comparable estimates of eye lens doses and tend to overestimate rather than underestimate the eye lens doses. The measured and estimated doses do not differ, on average, by a factor higher than 2.0 in 85% and 62% of the cases used to validate approach (a) and (b), respectively. In specific cases, however, the estimated doses differ from the measured ones by as much as a factor of 2.7 and 5.1 for method (a) and (b), respectively. As such, the two approaches can be considered accurate when retrospectively estimating the eye lens doses for ICs and will be of great benefit for ongoing epidemiological studies.

Dose reassessment method in thermoluminescent dosimetry by using the PTTL phenomena – A usefull tool

Introduction Reassessment of doses in film and OSL dosimetry is well known and standard method in contrary to TL dosimetry. By using the phototransferred thermoluminescence (PTTL) method which consist of the first readout, UV exposure and second readout it is possible to reassess doses in TL dosimetry. Purpose The PTTL method was developed and applied to reassess doses in whole body and ring dosimetry at Laboratory of Individual and Environmental Laboratory at IFJ PAN. Materials and methods Standard MTS-N (LiF: Mg, Ti) sintered thermoluminescent detectors (4.5 mm diameter and 0.9 mm thickness for whole body dosimeters and 0.7 mm thickness for ring dosimeters) have been applied. Some of them were used in routine control since 12 years. The TL detectors were read in automatic RE200 (Rados Oy, Finland) readers. After readout the PTTL method was applied. Detectors were subjected to UV radiation (254 nm length) and read once again in a reader. Results The PTTL method was applied to dose reassessment in individual and ring dosimetry. The reassessed doses are observed to be linear over the dose range 5–100 mSv in whole body dosimetry and 5–1000 mSv in ring dosimetry. Conclusion Due to checking behavior of different batches and different dose history it is possible to observe influence of residual dose to the PTTL effect. By using the PTTL method it is possible to reassess doses in whole body and ring dosimetry.

The value of protective head cap and glasses in neurointerventional radiology

BackgroundProtection of the head and eyes of the neurointerventional radiologist is a growing concern, especially after recent reports on the incidence of brain cancer among these personnel, and the revision...

TH-AB-BRA-11: Fear Not the Y-90 Surgical Staff Dose

Purpose: Patients with hepatic malignancies treated with ⁹⁰Y-microsphere brachytherapy are often precluded from liver transplantation for 4-weeks (∼10 half-lives) following therapy. This delay protects surgical staff from potential radiation dose but negatively impacts patients who could benefit from early transplantation post-therapy. We investigated the potential radiation dose to surgical staff performing early liver transplantation. Methods: Measured data from 30 treated patients were used to determine an average liver ⁹⁰Y-radioactivity concentration (Cavg= 60 µCi/cm3) and average maximum patient surface exposure rate (Ravg_max = 5.9 mR/h). Beta and bremsstrahlung dose rates at the liver surface were calculated from Cavg and Ravg_max respectively. These surface dose rates were compared with Monte Carlo (Geant4) simulated dose rates for a voxelized 1600 cm3 liver (Cliver = Cavg) containing a 5 cm diameter tumor (Ctumor = 3Cavg). The radiation dose to the hands of a transplant surgeon (Dhand) handling a radioactive liver for 2-hours was estimated using the calculated and Monte Carlo derived liver surface dose rates. Dhand was determined at different time-points post ⁹⁰Y-therapy. Results: Transplantation performed at 1-day and at 1-week post ⁹⁰Y-therapy resulted in Dhand<100 mSv and Dhand<20 mSv, respectively. At 1-week post-therapy, Dhand was less than 5% of the annual occupational dose limit to the hand (500 mSv). Calculated Dhand and Monte Carlo derived Dhand agreed within 20%. At the liver surface, bremsstrahlung dose rates were less than 1% of beta dose rates. Location of the liver tumor did not have a significant effect on Dhand. Conclusion: Potential radiation dose to surgical staff is low (<5% of annual limit) when performing liver transplantation in patients as early as 1-week after ⁹⁰Y microsphere brachytherapy. Future work aims to improve dosimetry by incorporating patient specific imaging data of the ⁹⁰Y radioactivity distribution and by measuring dose to surgical staff via ring and body dosimeters.

Occupational exposure to the whole body, extremities and to the eye lens in interventional radiology in Poland, as based on personnel dosimetry records at IFJ PAN

Abstract We report results of measurements of Hp(10) from whole body dosimeters (about 53 thousand readouts), of Hp(0.07) from finger ring dosimeters (23 thousand readouts) and of Hp(3) from eye lens dosimeters (100 readouts), issued in the years 2010–12 to over 150 medical departments in Poland which apply X-rays in radiology, interventional radiology (haemodynamic, angiology, cardiac surgery), urology, orthopaedics, electrophysiology or electro-cardiology. In all measurements thermoluminescence detectors (TLD) were used: the well-known standard MTS-N (LiF:Mg, Ti) for whole body and extremity dosimetry, and the high-sensitivity MCP-N (LiF:Mg, Cu, P) for eye lens dosimetry and environmental monitoring. We analysed the data base of the accredited Laboratory of Individual and Environmental Dosimetry (LADIS) at the Institute of Nuclear Physics PAN which offers its dosimetry service to these departments on a regular basis. We found that in the population of radiation workers that studied over the years 2010–2012 in 84%, 87%, and 34% of Hp(10), Hp(0.07) and Hp(3) measurements, respectively, the level of 0.1 mSv/quarter did not exceed, indicating lack of their occupational exposure. In the remaining 16%, 13% and 66% of individual cases, the 0.1 mSv/quarter exceeded, occasionally reaching several hundreds of mSv/quarter.

Intercomparisons for individual monitoring services in Europe: Organization, experience and results

The European Radiation Dosimetry Group (EURADOS) has set-up a worldwide unique program of self-sustainable international intercomparisons for individual monitoring services (IMS). Starting in 2008, with three intercomparisons for whole body photon dosimeters every 2 nd year, one intercomparison in 2009 for photon and beta extremity dosimeters and in 2012, an intercomparison for neutron whole body dosimeters, the intercomparisons became fundamental for the harmonization of radiation protection and individual monitoring in Europe. With the intercomparison results, the participants can show compliance within their quality management system, compare their results with those from other participants and develop plans for improvement of their system. The costs of the exercises are covered by the participant's fees. For the whole body photon intercomparisons a the number of participating systems increased from 62 in 2008 to 88 in 2012, showing the big demand for such exercises. Some of the system types like film dosimeters showed decreasing deviations of their results in the general and subsequently increased their quality in the dosimetric performance. The calibration of the systems showed to be an important factor for the performance of all system types. The intercomparison for extremity dosimeters for photon and beta radiation revealed large deviations for quite a few of the participating systems. The intercomparison actions are planned to be continued on a regular basis; the next whole body photon intercomparison is scheduled for 2014. International intercomparisons for IMS for external radiation will bring in improvement and harmonization in individual monitoring.

WE‐E‐108‐09: An Investigation of the Feasibility of Rodentmorphic 3D Dosimeters for Verification of Precision Micro‐Irradiator Treatment

Purpose: To evaluate the feasibility of novel rodentmorphic 3D dosimeters for comprehensive high‐resolution verification of the treatment accuracy of a state‐of‐the‐art micro‐irradiator equipped with on‐line cone‐beam‐CT guidance. Methods: Anatomically accurate 3D dosimeter molds were created in a two step procedure. First, rodents were CT scanned and the structures of interest contoured (e.g. body and spine). These contours were then exported for input to a 3D printer, to generate positive dosimeter molds. The rat body dosimeter was made of regular water‐equivalent PRESAGE, while the spine was made from high‐Z PRESAGE with an effective atomic‐number close to bone. Evaluation of the dosimeters involved (i) establishing the feasibility of manufacture and accurate positioning of heterogenous inserts, (ii) verification of accurate dose‐readout by optical‐CT, and (iii) verification of sufficient bony/soft‐tissue contrast for representative CBCT IGRT positioning. Simulated rat prostate treatments were delivered with dose of 16Gy given by 4 2.5cm diameter circular fields. Results: High resolution (0.5mm isotropic) 3D dosimetry data was acquired in rodentmorphic dosimeters both with and without the high‐Z spinal insert. The spinal insert was visible under kV radiographs and CBCT, demonstrating the feasibility of IGRT positioning. Pronounced edge artifacts were observed near the flat undersurface of the rat, and near regions of sharp curvature. Further artifacts were observed in some regions near the spinal insert caused by bubbles trapped during manufacture. New manufacturing procedures utilizing the flexibility of 3D printing to precisely customize contours in non‐critical regions have improved on both of these limitations. Conclusion: This work demonstrates promising feasibility for anatomically accurate 3D rodentmorphic dosimeters compatible with very high resolution 3D dosimetry. The ability to create such dosimeters is an important step forward in enabling accurate verification of complex micro‐irradiator treatments in the pre‐clinical setting. NIH Grant No. R01 CA 100835