Radiation Dose Limits Research Articles

Study on Airborne Radionuclide Dispersion in Floating Nuclear Power Plant under the Loss-of-Coolant Accident

Floating nuclear power plant is a kind of nuclear power plant on a barge moored specifically in an area of the sea. In order to study the factors influencing airborne radionuclide dispersion induced by the loss-of-coolant accident in floating nuclear power plant, the floating nuclear power plant platform was taken as the research object, and the dispersion of airborne radionuclide under combined conditions of platform positions, wind directions, and break directions (north, south, west, and east) was simulated by the CFD (computational fluid dynamics) method. The results show that northern and southern breaks have less dangerous island area than western and eastern ones but have more platform dangerous area than the western and eastern ones. The risk of the southern break is the greatest, and that of the western break is the least. Rotating the floating nuclear power plant platform in a certain angle can reduce the damage of loss-of-coolant accident. The effects of the dose received by the personnel under the condition of the severe accident were evaluated based on previous research, showing that the inhalation effective dose and the effective dose of plume immersion exposure were less than the radiation dose limit of 0.25 Sv within two hours in the accident. The results of the study can provide reference for the design of floating nuclear power plant platform and the formulation of emergency plan.

PD10-10 DON'T SKIRT THE QUESTION: LEAD BED SKIRTS IN THE OR, AN INTERVENTION

You have accessJournal of UrologyImaging/Radiology: Uroradiology I (PD10)1 Sep 2021PD10-10 DON'T SKIRT THE QUESTION: LEAD BED SKIRTS IN THE OR, AN INTERVENTION Jacob Thatcher, Thomas Mueller, and Katelyn Klimowich Jacob ThatcherJacob Thatcher More articles by this author , Thomas MuellerThomas Mueller More articles by this author , and Katelyn KlimowichKatelyn Klimowich More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000001978.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Fluoroscopy is an important tool in endourology. Residents spend a significant amount of time using fluoroscopy. Using extrapolated data collected from our OR using real time Geiger counters we showed that despite using low dose technology, leaded aprons and thyroid shields, the standard dose a resident receives over one year is 11% over the annual total radiation dose limit to the eyes and near the annual total dose radiation for the entire body. This doesn’t include the omnipresent ambient radiation exposure. The aim of our current study is to investigate the reduction in radiation exposure to the primary surgeon and anesthesia when a lead skirt is installed around the table. METHODS: We placed lead skirts circumferentially around the operating room table and placed Radex One Quarta Geiger Dosimeters at the level of the eyes, buttocks, anesthesia outer chest pocket and adjacent to the x-ray tube. We collected real time radiation exposure for each procedure. We compared these data with data collected using the same configuration without the lead operating room table skirt. RESULTS: Radiation exposure to various body parts during eighty-one endourologic procedures over a six-month period was tabulated. The normalized average was then compared. The highest amount of radiation received was to the eyes - 8.42μGy, followed by groin - 1.76μGy, backside - 1.53μGy, and inner chest - 1.07μGy per procedure. By simply installing a leaded skirt around the four sides of the table, we show that this attenuates the scattered dose radiation to all areas. Most notably, the reduction in radiation to the eyes is reduced from 8.42 to 1.46, a nearly 500% reduction in radiation (table 1). Similarly, radiation to the buttocks is reduced by almost 200%. Though these data are preliminary, they reflect a potential intervention that is simple, cost effective and revolutionary in fluoroscopy. CONCLUSIONS: Residents are exposed to high amounts of radiation during fluoroscopic procedures, which could be harmful. Dose exposure varies by body region. We show that the radiation to anesthesia is nearly equivalent to that of the primary surgeon. Installing a lead skirt around the table significantly reduces radiation scatter in the operating room. This represents a cheap and practical intervention to improve operating room safety. This intervention can be implemented across multiple specialties. Source of Funding: Rowan School of Medicine Grant © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e130-e131 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jacob Thatcher More articles by this author Thomas Mueller More articles by this author Katelyn Klimowich More articles by this author Expand All Advertisement Loading ...

Tumor Sink Effect in 68Ga-PSMA-11 PET: Myth or Reality?

We aimed to systematically determine the impact of tumor burden on 68Ga-prostate-specific membrane antigen-11 (68Ga-PSMA) PET biodistribution by the use of quantitative measurements. Methods: This international multicenter, retrospective analysis included 406 men with prostate cancer who underwent 68Ga-PSMA PET/CT. Of these, 356 had positive findings and were stratified by quintiles into a very low (quintile 1, ≤25 cm3), low (quintile 2, 25-189 cm3), moderate (quintile 3, 189-532 cm3), high (quintile 4, 532-1,355 cm3), or very high (quintile 5, ≥1,355 cm3) total PSMA-positive tumor volume (PSMA-VOL). PSMA-VOL was obtained by semiautomatic segmentation of total tumor lesions using qPSMA software. Fifty prostate cancer patients with no PSMA-positive lesions (negative scan) served as a control group. Normal organs, which included salivary glands, liver, spleen, and kidneys, were semiautomatically segmented using 68Ga-PSMA PET images, and SUVmean was obtained. Correlations between the SUVmean of normal organs and PSMA-VOL as continuous and categoric variables by quintiles were evaluated. Results: The median PSMA-VOL was 302 cm3 (interquartile range [IQR], 47-1,076 cm3). The median SUVmean of salivary glands, kidneys, liver, and spleen was 10.0 (IQR, 7.7-11.8), 26.0 (IQR, 20.0-33.4), 3.7 (IQR, 3.0-4.7), and 5.3 (IQR, 4.0-7.2), respectively. PSMA-VOL showed a moderate negative correlation with the SUVmean of the salivary glands (r = -0.44, P < 0.001), kidneys (r = -0.34, P < 0.001), and liver (r = -0.30, P < 0.001) and a weak negative correlation with the spleen SUVmean (r = -0.16, P = 0.002). Patients with a very high PSMA-VOL (quintile 5, ≥1,355 cm3) had a significantly lower PSMA uptake in the salivary glands, kidneys, liver, and spleen than did the control group, with an average difference of -38.1%, -40.0%, -43.2%, and -34.9%, respectively (P < 0.001). Conclusion: Tumor sequestration affects 68Ga-PSMA biodistribution in normal organs. Patients with a very high tumor load showed a significantly lower uptake of 68Ga-PSMA in normal organs, confirming a tumor sink effect. As similar effects might occur with PSMA-targeted radioligand therapy, these patients might benefit from increased therapeutic activity without exceeding the radiation dose limit for organs at risk.

A Review on Medical Image Super Resolution with Application of Deep Learning

Super resolution problems are often discussed in medical imaging. The spatial resolution of medical images is insufficient due to limitations such as image acquisition time, low radiation dose or hardware limitations. Various super-resolution methods have been proposed to solve these problems, such as optimization or learning-based approaches. Recently, deep learning methodologies have become a thriving technology and are evolving at an exponential rate. We believe we need to write a review to illustrate the current state of deep learning in super-resolution medical imaging. In this article, we provide an overview of image resolution and the deep learning introduced in super resolution. This document describes super resolution for single images versus super resolution for multiple images, evaluation metrics and loss functions.

High-dose-rate interstitial brachytherapy for vaginal endometrial cancer recurrence after prior surgery and radiotherapy

PurposeCharacterize the clinical outcomes of endometrial cancer vaginal recurrences after previous surgery and radiation therapy treated with reirradiation including image-guided interstitial high-dose-rate (HDR) brachytherapy. Methods and materialsA single-institution retrospective study identifying women receiving reirradiation for vaginal recurrence of endometrial cancer between 2004 and 2017. ResultsTwenty-three women had vaginal recurrences of endometrial cancer, median 13.7 months (range 3.5–104.9) from initial radiation. All received reirradiation with interstitial HDR brachytherapy, and seven also received external beam radiation. Median reirradiation EQD2_10 was 48 Gy (range 24.0–68.81), and median cumulative EQD2_10 was 106.25 Gy (range 62.26–122.0). Median follow-up after reirradiation was 40.2 months (range 4.5–112.7). At 3 years, overall survival was 56%, cancer-specific survival was 61%, and disease-free survival was 46%. 14 patients experienced disease recurrence; 10 including distant sites, one at a regional node only. Three patients experienced local recurrences, two of whom did not complete the prescribed course of reirradiation. The overall crude local control rate was 87%. Three patients experienced Grade 3 vaginal toxicity. There was no bladder or rectal toxicity with Grade >2. ConclusionsReirradiation including interstitial HDR brachytherapy is a promising option for vaginal recurrences of endometrial cancer after prior radiation, with high rate of local control and acceptable toxicity. However, distant failure is common. Further studies are needed to determine cumulative radiation dose limits and the role of systemic therapy in this scenario.

Knowledge, Attitude and Practice about radiation safety among the undergraduates in Eastern province dental college.

Background:Despite the fact that X-rays have a direct or indirect effect on tissues, imaging techniques have become an important part of modern dentistry, and dentists rely on them for diagnosis, treatment, and follow-up. This necessitates that dentists have adequate expertise and attitude in order to defend themselves and their patients.Aim:The present study was conducted to assess the knowledge, attitude, and practice of clinical side dental students and General Dental Practitioners (GDPs) regarding dental radiation protection safety protocol.Study Design:It is a prospective cross-section study among dental undergraduates and GDPs.Materials and Methods:One hundred and sixteen participants took part in this study and comprised 116 clinical side dental students and GDPs. Participants' data were gathered through a questionnaire that asked about their knowledge and practice of radiation biology, danger, and protection. Collected data subjected to statistical analysis using the SPSS 21. Pearson Chi-square test was done to evaluate the statistical significance. The P value fixed at ≤ 0.05 for significant.Results:From 116 participants, around 89.7%% of the participants believed that dental X-rays are harmful and 81% are having knowledge about annual radiation dose limit for a dentist, and overall, 56% of the participants were aware about the harmful effects of radiation exposure.Conclusion:There is a need to expand the curriculum to provide better exposure to radiation protection and its practice so that these students on graduation will be well-grounded with the principle governing dental radiography.

EVALUATION OF OCCUPATIONAL RADIATION EXPOSURE IN A RADIO-DIAGNOSTIC FACILITY IN KATSINA- NIGERIA

Poor implementation of quality assurance programs in the radiation industry has been a major setback in our locality. Several studies revealed that occupational workers are exposed to many potential hazards of ionizing radiation during radio-diagnostic procedures, yet radiation workers are often not monitored. This study aims to evaluate the occupational exposure of the radiation workers in Federal Medical Centre Katsina, and to compare the exposure with recommended occupational radiation dose limits. The quarterly readings of 20 thermo-luminescent dosimeters (TLDs') used by the radiation workers from January to December, 2019 were collected from the facility's radiation monitoring archive, and subsequently assessed and analyzed. The results indicate that the average annual equivalent dose per occupational worker range from 0.74 to 1.20 mSv and 1.28 to 2.21 mSv for skin surface and deep skin dose, measured at 10 mm and 0.07 mm tissue depth respectively. The occupational dose was within the recommended national and international limits of 5 mSv per annum or an average of 20 mSv in 5 years. Therefore, there was no significant radiation exposure to all the occupational workers in the study area. Though, the occupational radiation dose is within recommended limit, this does not eliminate stochastic effect of radiation. The study recommended that the occupational workers should adhere and strictly comply with the principles of radiation protection which includes distance, short exposure time, shielding and proper monitoring of dose limits. Furthermore, continuous training of the radiation workers is advised.

Noise suppression-guided image filtering for low-SNR CT reconstruction.

In practical computed tomography (CT) applications, projections with low signal-to-noise ratio (SNR) are often encountered due to the reduction of radiation dose or device limitations. In these situations, classical reconstruction algorithms, like simultaneous algebraic reconstruction technique (SART), cannot reconstruct high-quality CT images. Block-matching and 3D filtering (BM3D)-based iterative reconstruction algorithm (POCS-BM3D) has remarkable effect in dealing with CT reconstruction from noisy projections. However, BM3D may restrain noise with excessive loss of details in the case of low-SNR CT reconstruction. In order to achieve a preferable trade-off between noise suppression and edge preservation, we introduce guided image filtering (GIF) into low-SNR CT reconstruction, and propose noise suppression-guided image filtering reconstruction (NSGIFR) algorithm. In each iteration of NSGIFR, the output image of SART reserves more details and is used as input image of GIF, while the image denoised by BM3D serves as guidance image of GIF. Experimental results indicate that the proposed algorithm displays outstanding performance on preserving structures and suppressing noise for low-SNR CT reconstruction. NSGIFR can achieve more superior image quality than SART, POCS-TV and POCS-BM3D in terms of visual effect and quantitative analysis. Graphical abstract Block-matching and 3D filtering (BM3D)-based iterative reconstruction algorithm (POCS-BM3D) has remarkable effect in dealing with CT reconstruction from noisy projections. However, BM3D may restrain noise with excessive loss of details in the case of low-SNR CT reconstruction. In order to achieve a preferable trade-off between noise suppression and edge preservation, we introduce guided image filtering (GIF) into low-SNR CT reconstruction, and propose noise suppression-guided image filtering reconstruction (NSGIFR) algorithm.

Comparison of Hematologic Toxicity and Bone Marrow Compensatory Response in Head and Neck vs. Cervical Cancer Patients Undergoing Chemoradiotherapy.

Background: Hematologic toxicity is a critical problem limiting treatment delivery in cancer patients undergoing concurrent chemoradiotherapy. However, the extent to which anatomic variations in radiation dose limit chemotherapy delivery is poorly understood. A unique natural experiment arises in patients with head and neck and cervical cancer, who frequently undergo identical chemotherapy but receive radiation to different regions of the body. Comparing these cohorts can help elucidate to what extent hematologic toxicity is attributable to marrow radiation as opposed to chemotherapy.Methods: In this longitudinal cohort study, we compared hematologic toxicity and bone marrow compensatory response in 148 patients (90 cervix, 58 head/neck) undergoing chemoradiotherapy with concurrent weekly cisplatin 40 mg/m2. We used linear mixed effect models to compare baseline and time-varying peripheral cell counts and hemoglobin levels between cohorts. To assess bone marrow compensatory response, we measured the change in metabolically active bone marrow (ABM) volume on 18F-fluorodeoxyglucose positron emission tomography/computed tomography.Results: We observed greater reductions in log-transformed lymphocyte, platelet, and absolute neutrophil counts (ANC) for cervix compared to head/neck cancer patients (fixed effects for time-cohort interaction [95% CI]: lymphocytes, −0.06 [−0.09, −0.031]; platelets,−0.028 [-0.051, −0.0047]; ANC, −0.043 [−0.075, −0.011]). Mean ANC nadirs were also lower for cervical vs. head/neck cancer cohorts (2.20 vs. 2.85 × 103 per μL, p < 0.01). Both cohorts exhibited reductions in ABM volume within the radiation field, and increases in ABM volume in out-of-field areas, indicating varying compensatory response to radiation injury.Conclusions: Cervical cancer patients had faster decreases in ANC, lymphocyte, and platelet counts, and lower ANC nadirs, indicating a significant effect of pelvic irradiation on acute peripheral blood cell counts. Both cohorts exhibited a compensatory response with increased out-of-field bone marrow activity.

Radionuclide concentrations in medicinal florae and committed effective dose through Ayurvedic medicines

Purpose: Ayurveda is one of the oldest systems of medicines in the world being practiced widely in the Indian subcontinent for more than 3000 years, and still remains as one of the important traditional health care systems. The Ayurvedic drugs are derived primarily from various parts of the plants, like root, leaf, flower, fruit or plant as a whole. Plants uptake minerals and other nutrients from the soil through their root system. Along with other minerals radionuclides present in the growing media also reach to the plant parts following the same pathway. Realizing the probable health hazards via the intake of Ayurvedic drugs, it is important to assess the concentration of natural radionuclides in commonly used medicinal plants.Materials and methods: NaI(Tl) scintillator-based gamma-ray spectrometry has been used to determine the activity concentrations of primordial radionuclides (226Ra, 232Th and 40K) in the most commonly used medicinal plant parts as ingredients of Ayurvedic medicines in India.Results and discussion: The average specific activity (Bqkg−1) of 226Ra, 232Th and 40K was found to be 43 ± 18, 36 ± 15 and 230 ± 46, respectively. The estimated annual committed effective doses due to the intake of common Ayurvedic medicines at prescribed dosage was found to be 39 ± 16 µSv y−1, which is quite low as compared with the radiation dose limit of 1 mSvy−1 from all natural sources, reported by the International Commission on Radiological Protection (ICRP-60).Conclusions: It is found categorically that intake of Ayurvedic medicines at normal dosage poses no radiological hazard to the individual. Present results are significant in the wake of myths that many hazardous materials including radioisotopes are present at higher levels. Obtained results also serve as a reference information for the distribution of radionuclides in medicinal plant species.

Impact of tumor anatomic characteristics on patient radiation dose during transarterial chemoembolization

Objective: The aim of the study was to determine the association between anatomic tumor characteristics and the radiation dose in patients with hepatocellular carcinoma undergoing transarterial chemoembolization (TACE). Materials and Methods: A retrospective study was performed over a 42 months period. A total of 51 TACE procedures were included in the study. Information collected included: Gender, BMI, height, weight, cumulative dose area product (KAP), cumulative reference air kerma (RAK), maximum tumor diameter, multinodular tumors, and embolization material. Parametric univariate and simple linear regression analysis were used to determine associations between quantitative variables. Results: A total of 51 procedures in 37 patients, 19 women (51%) and 18 men (49%), with a mean age of 56 years (±17.3 years) and a mean BMI of 24 kg/m2 were included in the study. Overall, patient radiation dose was as follows: Mean KAP of 542.2 Gy* cm2 (±307 Gy* cm2) with a mean RAK of 2930.2 mGy (±1776.5 mGy). Higher patient radiation doses were observed in men (581.6 ± 262.9 Gy* cm2 vs. 497.8 ± 350.5 Gy* cm2) (P = 0.06) and in patients with higher BMIs (KAP: r = 0.37 [P = 0.01]; RAK: r = 0.4 [P = 0.01]). Patients with multinodular disease were found with lower radiation dose according to RAK (1710.7 ± 1118.6 mGy vs. 3227.7 ± 1789.1 mGy, P = 0.03). Furthermore, logistic regression analysis demonstrated that patients with multinodular disease received 10% lower dose, according to RAK, when compared to patients with single tumors (odds ratio 1.001, 95% confidence interval [CI], 1–1.002) (P = 0.02). Conclusion: TACE is an effective method to treat patients with HCC that may be performed within acceptable radiation dose limits. Anatomic tumor characteristics were found to be associated with patient radiation dose. Interestingly, multi-tumor disease was found to cause a radiation dose reduction of 10%.

Radiation protection in the cardiac catheterization laboratory.

The trend towards more minimally invasive procedures in the past few decades has resulted in an exponential growth in fluoroscopy-guided catheter-based cardiology procedures. As these techniques are becoming more commonly used and developed, the adverse effects of radiation exposure to the patient, operator, and ancillary staff have been a subject of concern. Although occupational radiation dose limits are being monitored and seldom reached, exposure to chronic, low dose radiation has been shown to have harmful biological effects that are not readily apparent until years after. Given this, it is imperative that reducing radiation dose exposure in the cardiac catheterization laboratory remains a priority. Staff education and training, radiation dose monitoring, ensuring use of proper personal protective equipment, employment of shields, and various procedural techniques in minimizing radiation must always be diligently employed. Special care and consideration should be extended to pregnant women working in the cardiac catheterization laboratory. This review article presents a practical approach to radiation dose management and discusses best practice recommendations in the cardiac catheterization laboratory.

LEVELS OF EXPOSURE TO IONIZING RADIATION AMONG THE PERSONNEL ENGAGED IN CYCLOTRON OPERATION AND THE PERSONNEL ENGAGED IN THE PRODUCTION OF RADIOPHARMACEUTICALS, BASED ON RADIATION MONITORING SYSTEM.

This paper aims to determine the levels of exposure to neutron and photon radiation among the personnel engaged in cyclotron operation and the personnel engaged in the production of radiopharmaceuticals, with the use of the environmental radiation monitoring system (RMS) installed in the positron emission tomography laboratory. The annual exposures of employees operating the cyclotron measured with the use of the RMS system are: 1.39 ± 0.16 mSv in case of photon radiation and 2.61 ± 0.14 mSv in case of neutron radiation. In the case of employees in the radiopharmaceuticals’ production zone, the annual exposures measured by means of the RMS system are 0.15 ± 0.03 mSv in case of photon radiation and 0.11 ± 0.01 mSv in case of neutron radiation. The exposure levels among the personnel engaged in cyclotron operation and the personnel engaged in the production of radiopharmaceuticals are below the permissible radiation dose limits.

Pengaruh Parameter Milliampere-Second (mAs) terhadap Kualitas Citra Dan Dosis Radiasi Pada Pemeriksaan CT scan Kepala Pediatrik

Radiographers are responsible for administering radiation doses according to the principle of As Low As Reasonably Achievable (ALARA), to optimize the use of CT parameters to produce good image quality by minimizing radiation doses. The purpose of this study was to determine the effect of mAs parameters on image quality and radiation dose received by pediatric CT head examination patients. The research method to perform image processing results of examination using radiant viewer and analysis of value Contrast to noise ratio (CNR) as a parameter of image quality and CTDIvol to determine the estimated radiation dose, then an analysis is performed to determine whether there is an influence of mAs on the CNR and CTDIvol values. The mean value of kV 116 ± 8.28, the mean value of parameter mAs 161.5 ± 63.46, the mean SNR parameter value is 7.5 ± 0.8, the mean return value of CNR parameter was 0.318 ± 0.291, the mean value of the CTDIvol parameter is 18.68 mGy ± 4.55 mGy, the average value of DLP parameters was 408.7 mGy x cm ± 105.2 mGy x cm, the mean value of parameter DLP is 441.2 mGy x cm ± 155.2 mGy x cm. With linear regression analysis of test results between mAs to CNR is R2 = 0.045. then to the results of linear regression between mAs against CTDI is R2 = 0704, the estimated radiation dose limit for the average value of CTDIvol 18.68 mGy and the average value of DLP 408.7 mGy x cm, this means the protocol CT scan of the head of the pediatric use is still within safe limits by Diagnostic Reference Level of BAPETEN in 2018 to pediatric head CT examination

Radiation damage and dose limits in serial synchrotron crystallography at cryo- and room temperatures

Radiation damage limits the accuracy of macromolecular structures in X-ray crystallography. Cryogenic (cryo-) cooling reduces the global radiation damage rate and, therefore, became the method of choice over the past decades. The recent advent of serial crystallography, which spreads the absorbed energy over many crystals, thereby reducing damage, has rendered room temperature (RT) data collection more practical and also extendable to microcrystals, both enabling and requiring the study of specific and global radiation damage at RT. Here, we performed sequential serial raster-scanning crystallography using a microfocused synchrotron beam that allowed for the collection of two series of 40 and 90 full datasets at 2- and 1.9-Å resolution at a dose rate of 40.3 MGy/s on hen egg white lysozyme (HEWL) crystals at RT and cryotemperature, respectively. The diffraction intensity halved its initial value at average doses (D1/2) of 0.57 and 15.3 MGy at RT and 100 K, respectively. Specific radiation damage at RT was observed at disulfide bonds but not at acidic residues, increasing and then apparently reversing, a peculiar behavior that can be modeled by accounting for differential diffraction intensity decay due to the nonuniform illumination by the X-ray beam. Specific damage to disulfide bonds is evident early on at RT and proceeds at a fivefold higher rate than global damage. The decay modeling suggests it is advisable not to exceed a dose of 0.38 MGy per dataset in static and time-resolved synchrotron crystallography experiments at RT. This rough yardstick might change for proteins other than HEWL and at resolutions other than 2 Å.

Abstract C52: The radioprotector GC4419 enhances the response of PDAC tumors to high dose per fraction radiation exposure

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths in the United States, with an estimated 5-year overall survival rate of ~6%. While surgery followed by adjuvant therapy is the standard of care, most patients present with advanced disease. Recent clinical trials have demonstrated that the traditional radiation dose limit of 50.4 Gy to tumors located at the head of the pancreas is not sufficient to generate tumor control at doses tolerable to the jejunum; however, doses exceeding 60 Gy, particularly when delivered as stereotactic body radiation therapy (SBRT), drastically enhance progression free-survival at 2 years. Here, we present evidence that the radioprotector GC4419 (Galera Therapeutics, St. Louis, MO) whose enantiomer, GC4403, has demonstrated radioprotective properties against GI toxicity, sensitizes PDAC cells and xenografts to radiation exposure. Furthermore, combination therapy with immune oncology agents targeting the PD-L1 pathway enhanced the response of Panc02 tumors (syngeneic to C57.BL/6 mice) to combined radiation and immune therapy. These results present the foundation for a newly initiated dose-escalation clinical trial for treating PDAC tumors with GC4419 and SBRT. Citation Format: Michael D. Story, Brock J. Sishc. The radioprotector GC4419 enhances the response of PDAC tumors to high dose per fraction radiation exposure [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C52.

Monitoring Radiation Exposure of Saudi Aramco Pilots.

A 1 y study to monitor exposure to cosmic radiation of pilots and aircrew in Saudi Aramco flights has been conducted. In many countries, flight attendants, pilots, and other aircrew are considered to be radiation workers. Five pilots participated in the study, and two methods were used for measuring or estimating the radiation doses received by pilots or aircrew during air flights: the computer program CARI-7 and thermoluminescent dosimeters. It has been concluded that although pilots and aircrew are occupationally exposed to ionizing radiation, they do not receive enough radiation to be included in the company radiation dosimetry program. Although it is not possible, in general, for pilots and aircrew to reach the occupational dose limit, they nonetheless should be monitored (using a computer simulation code) to be in line with international practices. In the case of pregnant aircrew, it is particularly important to monitor their radiation doses, because it is possible for them to reach their radiation dose limits.

Assessing radiation dose limits for X-ray fluorescence microscopy analysis of plant specimens.

X-ray fluorescence microscopy (XFM) is a powerful technique to elucidate the distribution of elements within plants. However, accumulated radiation exposure during analysis can lead to structural damage and experimental artefacts including elemental redistribution. To date, acceptable dose limits have not been systematically established for hydrated plant specimens. Here we systematically explore acceptable dose rate limits for investigating fresh sunflower (Helianthus annuus) leaf and root samples and investigate the time-dose damage in leaves attached to live plants. We find that dose limits in fresh roots and leaves are comparatively low (4.1 kGy), based on localized disintegration of structures and element-specific redistribution. In contrast, frozen-hydrated samples did not incur any apparent damage even at doses as high as 587 kGy. Furthermore, we find that for living plants subjected to XFM measurement in vivo and grown for a further 9 d before being reimaged with XFM, the leaves display elemental redistribution at doses as low as 0.9 kGy and they continue to develop bleaching and necrosis in the days after exposure. The suggested radiation dose limits for studies using XFM to examine plants are important for the increasing number of plant scientists undertaking multidimensional measurements such as tomography and repeated imaging using XFM.

Proposed Dose Constraints in the Duties of Radiation Workers at the Department of Nuclear Medicine.

This study aimed to set a dose constraint for certain duties of radiological technologists in the department of nuclear medicine. From 2013 to 2017, the 5 y radiation exposure data of employees performing PET-CT and γ-CAMERA of eight hospitals in Korea were measured individual exposure doses to estimate the frequency and set a representative dose of 75 and 95% from the low dose in the whole category is presented. The dose constraint was 5.5mSv for PET-CT, 4.5mSv for γ-CAMERA and 3.5mSv for Positron Emission Tomography (PET)-Computed Tomography(CT) and Gamma CAMERA (γ-CAMERA). Therefore, it would be appropriate to set a dose-limit value of ~5mSv corresponding to 75-80% of the individual exposure dose of radiological technologists in the department of nuclear medicine. The finding of this study may be used as reference data for setting future radiation dose limits.

HYGIENIC ASSESSMENT OF X-RAY AND LASER RADIATION AT SURGEONS’ WORKPLACES

Introduction. Modern surgery is a complex, multifaceted area of medicine that plays an important role in the struggle for health, working capacity and human life. In recent years, in surgery, much attention has been paid to the improvement and development of new surgical equipment, including that based on ionizing and non-ionizing radiation, its application range being widened, which allows patients being provided with high-tech and less traumatic procedures. However, the use of such equipment resulted in the appearance of new adverse occupational factors of ionizing and non-ionizing nature at the workplaces of surgical team members, which can have a negative effect on the personnel. Material and methods. Data of x-ray and laser radiation level studies at the workplaces of medical personnel in modern operating rooms are reported. Results. Total normalized power of the effective x-ray dose during the use of x-ray surgical unit at the workplaces of surgical teams in most cases was revealed not to exceed allowable dose rate, while in the process of certain procedures, such as vessel embolization, it can exceed allowable levels. The total annual effective radiation exposure dose of x-ray surgery teams depends on the number of performed operations, their type, complexity, and can exceed a basic radiation dose limit for A and B group personnel. The intensity of diffusely reflected laser radiation at workplaces of surgeons can significantly exceed maximum allowable levels, sometimes up to 600 times. Discussion. Considering an ever-gaining use of high-tech equipment generating laser and X-ray radiation and increasing number of exposed medical personnel, hygienic assessment of these radiation levels at workplaces of surgical team members and development of measures to improve working conditions is an important issue for maintaining workers’ health. Conclusion. To assess the occupational risk degree to the health of surgeons it is necessary to conduct in-depth studies of their health status.