Maximum Effective Dose Research Articles

Public ingestion exposure to 226Ra in Ramsar, Iran

Ramsar, in the north of Iran by the Caspian Sea, has been known for the highest natural radiation background on Earth due to the local geology and hydrogeology. The residents and visitors use the hot springs that distribute the natural radionuclides especially 226Ra and its decay products in the areas. Many studies have been undertaken to measure the absorbed dose rate in Ramsar's air, however, no survey has been done to assess public internal exposure from ingestion of natural radionuclides, such as, a broad survey for 226Ra was conducted in foodstuffs and drinking water. This study presents the results of public annual activity intake (Bq) and effective dose (μSv) from ingestion of 226Ra in foodstuffs and drinking water in Ramsar city. The total mean annual intake for adults was found to be 24.8 Bq. The annual average effective dose due to ingestion exposure to 226Ra was found to be 6.9 μSv for adults that were slightly more than the estimated global averages reported by UNSCEAR, 2000 (6.3 μSv). The contribution of drinking water and foodstuffs represent respectively about 30% and 70% of the total mean annual effective dose due to 226Ra. The highest effective dose from ingestion of 226Ra for adults was estimated to be 80.6 μSv y−1. Based on the results of this study, even with the largest 226Ra value in our survey, maximum annual effective dose due to consumption of foodstuffs and drinking water for children was 164.2 μ b Sv y−1.

ASSESSMENT OF ANNUAL EFFECTIVE DOSE FROM EXPOSURE TO NATURAL RADIOACTIVITY SOURCES IN A CASE-CONTROL STUDY IN BIHOR COUNTY, ROMANIA.

The purpose of the article is to evaluate the annual effective dose for 80 women divided into two samples; one sample located in the former uranium Băiţa-Ştei area, hereinafter referred to as case sample, respectively for a control sample, located in the same county, but exposed in most cases to indoor radon activity concentrations <300 Bq m-3. In this regard, the homemade 'RaThoGamma' kit was used, which contained two thermoluminescent dosimeters, a CR-39 track detector (RSKS) for indoor radon activity concentration, two CR-39 track detectors (Radtrak2®/ Radtrak2T®) for radon and thoron activity concentrations as well as Direct Radon Progeny Sensors/Direct Thoron Progeny Sensors for measuring time-averaged radon and thoron progenies concentrations. In addition, a total of 80 water samples were collected in order to evaluate the ingestion dose due to radon and radium activity concentrations in drinking water. The maximum total annual effective dose in the control sample was 14.1 mSv, while in the case sample the maximum annual effective dose was 60.5 mSv. This difference is mainly due to radon progenies inhalation. Other pathways did not show a statistically significant difference between the two samples, showing a minor contribution to the annual effective dose.

Weighty Choices: Selecting Optimal G-CSF Doses for Stem Cell Mobilization to Optimize Yield

Introduction. There is little information on the effect of donor body mass index (BMI) on mobilization response to Filgrastim (G-CSF), especially in the unrelated donor setting. Obesity has been associated with chronic low-grade inflammation due to chronic activation of the innate immune system. Obesity-induced pro-inflammatory cytokines can interfere with bone marrow SDF1/CXCR4 axis and promote mobilization of progenitor cells leading to persistent leukocytosis and an increase in number of circulating progenitor cells. Given a higher number of circulatory progenitor cells in obese individuals compared to non-obese, a reduced G-CSF dose in obese donors may elicit adequate response, thus reducing the adverse events associated with peripheral blood stem cell (PBSC) collection. The aim of this study is to evaluate the impact of donor BMI on G-CSF mobilized peripheral blood progenitor cell yield in healthy donors. This study also examines whether there is a G-CSF dose threshold above which there is a significant increase in skeletal pain and other acute toxicities from mobilization without an appreciable increase in progenitor cell yield.Methods. The primary outcome was examination of CD34+ per liter of blood processed (x106/L) on Day 5 of G-CSF administration as a measure of collection yield. The secondary outcomes were the incidence of skeletal pain and highest toxicity level across selected body symptoms (fatigue, nausea, anorexia, insomnia, dizziness) at 24 hours after first G-CSF dose, day 1 to 5 of G-CSF administration, 2 days and 1-week post collection. The population studied was domestic unrelated G-CSF mobilized PBSC donors reported to the NMDP/CIBMTR between 2006 and 2016. G-CSF dosing was based on the NMDP weight-based dosing schema rounded to the nearest vial content. Donors were divided into normal, overweight, obese, and morbidly obese categories based on BMI. Multivariate analysis of collection yields between cohorts were done using linear regression analysis. Stepwise variable selection was used to add variables to the model: BMI group and G-CSF dose was forced into the final model as the variables of interest. Pain and acute toxicities at each time point were described using frequencies and compared between groups using chi-squared test or Fisher's exact test after adjusting for donor and baseline characteristics.Results. Examination of 20, 884 PBSC donors mobilized by G-CSF revealed a significant increase in collection yield in obese and morbidly obese compared to normal and overweight donors. Median CD34+ per liter of blood processed (x106/L) on Day 5 of G-CSF was 29.6, 36.4, 40.8 and 42.9 in normal, overweight, obese and morbidly obese donors, respectively (p<0.001). Based on the subgroup analyses evaluating impact of average daily dose of G-CSF on the collection yield for each BMI group, an increase in average daily G-CSF dose was associated with an increase in stem cell yield in normal and overweight BMI donors. In contrast, an increase in the average daily G-CSF dose beyond 780 mcg per day in obese and 900 mcg per day in morbidly obese did not increase the yield (Table 1).Figure 1 shows the time course and degree of toxicities in different BMI categories. Obese and morbidly obese were more likely to experience grade 2-4 pain and toxicities compared with normal or overweight in both the peri-collection and early post-donation recovery period but by one week after donation most toxicities abated and there was no difference. Donors with a higher BMI were more likely to experience grade 2 to 4 skeletal pain 24 hours post first G-CSF dose, 2 days post donation and at day 1 to 5 G-CSF administration. In addition, donors with higher BMI were more likely to have grade 2-4 toxicities (fatigue, anorexia, insomnia) at day 1 to 5 of G-CSF and 2 days after collection. However, within each BMI group, incremental increase in G-CSF dose was not associated with greater pain or other toxicities.Conclusions. Our data indicates a correlation between average daily G-CSF dose and CD34+ cell yield in normal and overweight donors. However, in obese and morbidly obese donors, there was no benefit in CD34+ yield with increasing average daily G-CSF dose above 780 mcg and 900 mcg respectively. Therefore, there appears to be a maximum effective G-CSF dose for mobilization in obese and morbidly obese donors where higher doses of G-CSF add no additional benefit and may result in additional complications. [Display omitted] DisclosuresPulsipher:Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen: Honoraria; Adaptive Biotech: Consultancy, Research Funding; CSL Behring: Consultancy.

Determining RBE for development of lung fibrosis induced by fractionated irradiation with carbon ions utilizing fibrosis index and high-LET BED model

Background and purposesCarbon ion radiotherapy (CIRT) with raster scanning technology is a promising treatment for lung cancer and thoracic malignancies. Determining normal tissue tolerance of organs at risk is of utmost importance for the success of CIRT. Here we report the relative biological effectiveness (RBE) of CIRT as a function of dose and fractionation for development of pulmonary fibrosis using well established fibrosis index (FI) model. Materials and MethodsDose series of fractionated clinical quality CIRT versus conventional photon irradiation to the whole thorax were compared in C57BL6 mice. Quantitative assessment of pulmonary fibrosis was performed by applying the FI to computed tomography (CT) data acquired 24-weeks post irradiation. RBE was calculated as the ratio of photon to CIRT dose required for the same level of FI. Further RBE predictions were performed using the derived equation from high-linear energy transfer biologically effective dose (high-LET BED) model. ResultsThe averaged lung fibrosis RBE of 5-fraction CIRT schedule was determined as 2.75 ± 0.55. The RBE estimate at the half maximum effective dose (RBEED50) was estimated at 2.82 for clinically relevant fractional sizes of 1–6 Gy. At the same dose range, an RBE value of 2.81 ± 0.40 was predicted by the high-LET BED model. The converted biologically effective dose (BED) of CIRT for induction of half maximum FI (BEDED50) was identified to be 58.12 Gy3.95. In accordance, an estimated RBE of 2.88 was obtained at the BEDED50 level. The LQ model radiosensitivity parameters for 5-fraction was obtained as αH = 0.3030 ± 0.0037 Gy−1 and βH = 0.0056 ± 0.0007 Gy−2. ConclusionThis is the first report of RBE estimation for CIRT with the endpoint of pulmonary fibrosis in-vivo. We proposed in present study a novel way to mathematically modeling RBE by integrating RBEmax and α/βL based on conventional high-LET BED conception. This model well predicted RBE in the clinically relevant dose range but is sensitive to the uncertainties of α/β estimates from the reference photon irradiation (α/βL). These findings will assist to eliminate current uncertainties in prediction of CIRT induced normal tissue complications and builds a solid foundation for development of more accurate in-vivo data driven RBE estimates.

Radon and Its Effect on the Radiation Situation in the Chernobyl NPP Sarcophagus

During studies performed in 2010–2014, in the under-reactor rooms and deaerator stack of the sarcophagus at the Chernoby NPP, the average volume activity of radon was ~100 Bq/m3 and the average coefficient of equilibrium of radon and its daughter products was ~0.7. The maximum volume activity of radon reached 666 Bq/m3. The daughter products complicate radiation monitoring of the aerosol situation. In the inspected rooms of the under-reactor space and deaerator stack, the radiation exposure of workers due to inhalation of radon, thoron, and their daughter products can exceed 10% of the maximum admissible effective dose. It was determined that the carrier aerosols of the daughter products are submicron aerosols with active median aerodynamic diameter ~0.1 μm. The arch erected above the sarcophagus at the end of 2016 can degrade the radon radiation situation because of reduction of the natural ventilation.

Radiation Exposure to the Sacroiliac Joint From Low-Dose CT Compared With Radiography

The primary objective of this study was to estimate the effective dose delivered to the sacroiliac joint (SIJ) from low-dose (LD) CT compared with that from radiography. Secondary objectives included evaluation of diagnostic quality of LD CT of the SIJ and development of a clinical protocol for LD CT of the SIJ. Data from 36 patients (19 women, 17 men) undergoing LD CT for suspected renal colic were analyzed. Two effective dose estimates were calculated: one for the SIJ and another for an extended region from the iliac crest to 1 cm below the SIJ. Thirty-six anteroposterior pelvic and 36 SIJ view radiographs were age-, sex-, and body width-matched to CT scans. Effective dose from radiography was estimated using the method described in International Commission on Radiologic Protection Publication 60. Maximum effective dose to the SIJ from LD CT was less than 1 mSv in all cases, with a mean ± SD of 0.42 ± 0.18 mSv (range, 0.14-0.83 mSv), whereas mean dose to the extended region was 0.57 ± 0.24 mSv (range, 0.19-1.11 mSv). Mean dose from SIJ radiographs was 0.15 ± 0.10 mSv (range, 0.07-1.38 mSv), and mean dose from a single pelvic radiograph was 0.09 ± 0.06 mSv (range, 0.04-0.37 mSv). All CT studies were of diagnostic quality for assessment of the SIJ. LD CT of the SIJ can be consistently performed with an effective radiation dose of less than 1 mSv. Because reliability and sensitivity of radiography for sacroiliitis is poor, we recommend that LD CT replace radiography for dedicated evaluation of the SIJ.

A combined proof of concept and dose finding study with multiple endpoints: A Bayesian adaptive design in chronic prostatitis/chronic pelvic pain syndrome

There is a need for identifying effective drugs or terminating ineffective drugs as early as possible to optimize efficient and cost effective drug development. The aim of the proposed trial was to simultaneously establish Proof of Concept (PoC) and dose finding (DF) for a new drug with a novel mode of action in a new indication. We simulated and executed an adaptive allocation design to investigate the effects of a drug on male patients suffering from chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). This manuscript describes the clinical trial simulations and primary analysis results. A Bayesian adaptive allocation procedure was employed to allocate patients to treatment using a normal dynamic linear model. The study was to stop early for efficacy if the probability of a clinically significant difference between an experimental arm and placebo was at least 90%. The study was to stop for futility if the probability that the maximum effective dose was better than placebo by at least the futility difference was less than 20%. During the execution phase the study was stopped early, that is 32% less than planned maximum sample size, due to futility. The final results confirmed that the predefined stopping rules were met. In conclusion, the simulations showed that, if the drug was effective, this adaptive design could accomplish both the goals of PoC and DF. However, the study stopped early for futility in line with the simulation predictions for stopping. This resulted in the early stopping of a trial recruiting patients on ineffective treatment.

Abstract 4104: Evaluation of a novel LDH inhibitor efficacy in vivo in a glycolytic cancer model using hyperpolarized 13C magnetic resonance imaging

Abstract Increased conversion of pyruvate to lactate by Lactate Dehydrogenase A (LDHA) is a feature of many neoplasms. Therefore, LDHA inhibition is considered a promising approach toward developing a new therapeutic strategy against cancers expressing the Warburg phenotype. To develop this strategy for clinical use, a feasible and sensitive noninvasive imaging approach that can dynamically evaluate LDHA activity in vivo would be highly beneficial since in vitro metabolic profiling dose not always predict in vivo cancer metabolism. Hyperpolarized (HP) 13C Magnetic Resonance Imaging (MRI) can be used to perform dynamic 13C metabolic flux analysis in vivo. In particular, use of [1-13C]pyruvate (13C-pyr) with 13C MRI permits real-time monitoring of intratumoral LDHA activity through dynamic observation of conversion of 13C-pyr to [1-13C]lactate (13C-lac). This study aimed to apply 13C MRI technology in support of a therapeutic strategy to explore efficacy of a newly developed and highly potent LDH inhibitor (LDHi) in a glycolytic tumor model using MiaPaCa2 xenografts in mice. In vitro analysis showed that the LDHi dose-dependently inhibited human LDH activity and suppressed in vitro cell growth in MiaPaCa2 cells. By ex vivo assay, LDH activity in MiaPaCa2 xenografts was significantly suppressed (82.2 ± 5.6 % decrease compared to vehicle controls) following a single intravenous(IV) injection of 50 mg/kg LDHi. Next, 13C MRI imaging of HP 13C-pyr metabolism was performed before and after a single LDHi IV injection to assess inhibitor impact on intratumoral metabolic flux in vivo. 13C MR spectroscopy confirmed that LDHi suppressed intratumor LDHA activity dose- and time-dependently. The maximum effective dose was 50 mg/kg and inhibitor impact in the tumor persisted for 10-12 hrs after a single injection. In addition, lactate production in the tumor was suppressed 30 minutes after IV administration of LDHi, as was the 13C-lac to 13C-pyr ratio decreased by 83.3 ± 4.4 % compared to vehicle controls. Importantly, the close correlation of these data with the results of the ex vivo LDH activity assay, suggests that 13C MRI can reliably monitor in vivo on target effects of LDHi without need for tissue sampling. Based on the data using 13C MRI, we developed a therapeutic strategy for using LDHi in an efficacy study of MiaPaCa2 xenografts. Intermittent IV administration of LDHi significantly suppressed tumor growth in this glycolytic model. In conclusion, intratumoral inhibition of LDHA in vivo upon IV administration of a novel LDHi was readily visualized by HP 13C MRI, confirming the utility of this noninvasive method. This methodology can be of great value in developing new therapeutic strategies using LDHi and perhaps other metabolic inhibitors to treat cancers characterized by the Warburg phenotype. Further, HP 13C MRI should allow for selection of those patients likely to respond to such treatments. Citation Format: Nobu Oshima, Shun Kishimoto, Kristin Beebe, Dan Crooks, Michael Moses, Kazutoshi Yamamoto, Jeffry R. Brender, Anastasia Sowers, Ganesha Rai, Daniel Urban, Goria Benavides, Giuseppe Squadrito, Victor Darley-Usmar, Matthew Hall, James B. Mitchell, Murali C. Krishna, Leonard M. Neckers. Evaluation of a novel LDH inhibitor efficacy in vivo in a glycolytic cancer model using hyperpolarized 13C magnetic resonance imaging [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4104.

Indoor Radon Levels and Effective Dose Estimation in Learning and Common Living Space of University

Radon which is natural component of air is a colorless and odorless radioactive gas. Radon exposure can also occur from some building materials if they are made from radon-containing substances by breathing. In this study, The radiation dose of radon concentration was detected at 8 buildings of the A university during 3-month from June. 2017 to August. 2017. We detected indoor radon exposure at 8 building of the university and estimated annual effective dose. The radon concentration of Hall G and Hall F of the A university represented 81 and 14 Bq/㎥ respectively and average indoor radon concentration represented 41.63 Bq/㎥. Average effective dose was estimated 0.40 mSv/y, maximum effective dose was 0.78 mSv/y and minimum effective dose was 0.13 mSv/y respectively. University is the place that students spend the almost whole time. We suggest ventilation and appropriate management of a building, which could reduce the natural radiation exposure by radon concentration.

Technical Note: A proposal of air ventilation system design criteria for a clinical room in a heavy-ion medical facility.

An optimized air ventilation system design for a treatment room in Heavy-ion Medical Facility is an important issue in the aspects of nuclear safety because the activated air produced in a treatment room can directly affect the medical staff and the general public in the radiation-free area. Optimized design criteria of air ventilation system for a clinical room in 430MeV/u carbon ion beam medical accelerator facility was performed by using a combination of MCNPX2.7.0 and CINDER'90 codes. Effective dose rate and its accumulated effective dose by inhalation and residual gamma were calculated for a normal treatment scenario (2min irradiation for one fraction) as a function of decay time. Natural doses around the site were measured before construction and used as reference data. With no air ventilation system, the maximum effective dose rate was about 3μSv/h (total dose of 90mSv/y) and minimum 0.2μSv/h (total dose of 6mSv/y), which are over the legal limits for medical staff and for the general public. Although inhalation dose contribution was relatively small, it was considered seriously because of its long-lasting effects in the body. The integrated dose per year was 1.8mSv/y in the radiation-free area with the 20-min rate of air ventilation system. An optimal air ventilation rate of 20min is proposed for a clinical room, which also agrees with the best mechanical design value.

POTENTIALLY POSSIBLE POPULATION EXPOSURE DOSES DUE TO MINERAL NATURAL MEDICAL WATER CONSUMPTION

Mineral natural table, medical-table and medical water is usually characterized by enhanced mineralization, so annual consumption of such water for drinking and cooking is much lower than standard water consumption of adult population. The limitation of population exposure due to mineral natural table and medical-table water could be achieved by the implementation of limitation of their consumption. The aim of the investigation is to estimate potentially possible population exposure doses from mineral natural medical water consumption on an example of the water which is used for drinking therapy in the complex of sanatorium health resort treatment of patients in one of the sanatoriums of Saint-Petersburg. The data on mineral medical water radionuclides specific activity values used for patients exposure doses estimation was obtained during implemented radiochemical analysis carried out using the techniques developed in the Institute of Radiation Hygiene. Obtained results of the investigations and their analysis demonstrated that potentially possible patients’ maximal annual effective exposure doses due to implementation of mineral natural medical water for drinking therapy in the complex of sanatorium health resort treatment will not exceed definitely the reference dose level, recommended by WHO, equal to 0.1 mSv/year because of a low amount of water consumption prescribed by a physician. It is clear unreasonable to set limitations on natural radionuclides content in mineral medical water because patients take it as a medicine according to physician prescribing and the consumption of such water is connected with their therapy properties. Principle of justification of the procedures appointment has to be applied when the course of mineral medical water treatment is prescribed. The essence of the principle is to compare therapy (medical) benefits as a result of treatment with the damage to health as a result of radiation exposure. It is necessary to estimate the effective internal exposure doses due to mineral natural medical water consumption for different age groups of population for the process of justification of therapy procedures.

Dose-response and efficacy of spinal manipulation for care of cervicogenic headache: a dual-center randomized controlled trial

Background ContextThe optimal number of visits for the care of cervicogenic headache (CGH) with spinal manipulative therapy (SMT) is unknown. PurposeThe present study aimed to identify the dose-response relationship between visits for SMT and chronic CGH outcomes and to evaluate the efficacy of SMT by comparison with a light-massage control. Study Design/SettingThis is a two-site, open-label randomized controlled trial. Patient SampleParticipants were 256 adults with chronic CGH. Outcome MeasuresThe primary outcome was days with CGH in the previous 4 weeks evaluated at the 12- and 24-week primary end points. Secondary outcomes included CGH days at remaining end points, pain intensity, disability, perceived improvement, medication use, and patient satisfaction. MethodsParticipants were randomized to four dose levels of chiropractic SMT: 0, 6, 12, or 18 sessions. They were treated three times per week for 6 weeks and received a focused light-massage control at sessions when SMT was not assigned. Linear dose effects and comparisons with the no-manipulation control group were evaluated at 6, 12, 24, 39, and 52 weeks. The present study was funded by the National Center for Complementary and Integrative Health (R01AT006330) and is registered at ClinicalTrials.gov (NCT01530321). The authors declare no conflicts of interest. ResultsA linear dose-response was observed for all follow-ups, a reduction of approximately 1 CGH day/4 weeks per additional 6 SMT visits (p<.05); a maximal effective dose could not be determined. Cervicogenic headache days/4 weeks were reduced from about 16 to 8 for the highest and most effective dose of 18 SMT visits. Mean differences in CGH days/4 weeks between 18 SMT visits and control were −3.3 (p=.004) and −2.9 (p=.017) at the primary end points, and were similar in magnitude at the remaining end points (p<.05). Differences between other SMT doses and control were smaller in magnitude (p>.05). Cervicogenic headache intensity showed no important improvement nor differed by dose. Other secondary outcomes were generally supportive of the primary outcome. ConclusionsThere was a linear dose-response relationship between SMT visits and days with CGH. For the highest and most effective dose of 18 SMT visits, CGH days were reduced by half and about 3 more days per month than for the light-massage control.

Analysis of the caregiver effective dose during I-131 therapy of thyroid.

The main objective of the present research is to analyze the caregiver effective dose during I-131 therapy of thyroid in some different situations using MCNP4C Monte Carlo code. Two separate whole body Medical Internal Radiation Dosimetry (MIRD) phantoms have been defined simultaneously in a single Monte Carlo N-Particle (MCNP) input file as the patient and the caregiver. Two different groups of irradiation situations have been assumed for the caregiver related to the patient, (1) both the patient and the caregiver are standing and (2) the patient is lying in the bed while the caregiver is standing beside the patient. The results show that the caregiver effective dose is highly dependent on the position of the caregiver related to the patient. When the patient is lying on the bed and the caregiver is standing beside the patient near the head of the patient, the effective dose of caregiver will be the maximum value. Although the maximum effective dose (0.2 mSv) is smaller than the allowed value for caregivers (5 mSv for each treatment), the final results of this research indicate the importance of caregiver position in close contact with the patient.

Radiological effect of cask-drop accident in open-pool spent fuel storage

This study investigates the radiological risk that may occur during transport of cobalt device after irradiation in open-pool-type reactor from the reactor core to the cobalt cell. The cobalt transport process depends on using heavy shielded cask of 3500 kg weight under the water surface of the spent fuel storage pool which may cause a load drop accident. The load drop accident in the spent fuel storage pool would result in damage of 48 spent fuel elements (FE) maximally. Conservative evaluation for the amount of fission products release from the damage of the spent FE was considered in this study by assuming that all spent FE was recently stored at the time of accident. Consequently, the resulting radiation dose distribution was calculated around the reactor building depending on the meteorological data of the reactor site. GENII-2 code was used to estimate the individual effective dose distribution around the reactor. The result shows that the receptor who located at 1500 m from the reactor building in the south-east direction will receive the maximum individual effective dose of 0.11 Sv.

Assessment of Effective Dose Associated with Coronary Computed Tomography Angiography in Isfahan Province, Iran

Computed tomography coronary angiography (CTCA) has generated a great interest over the past two decades, due to its high diagnostic accuracy and efficacy in the assessment of patients having coronary artery disease. This method is associated with high radiation dose and this has raised serious concerns in the literature. Effective dose (E) is a single parameter meant to reflect the relative risk from exposure to ionizing radiation. Therefore, it is necessary to calculate this parameter to indicate ionizing radiation relative risk. The aim of this study was to calculate the effective dose from 64-slice CTCA in Isfahan. To calculate the effective dose, an ionization chamber and a body phantom with diameter of 32 cm and length of 15 cm were used. CTCA radiation conditions commonly used in two centers were applied for this work. For all scans, computed tomography volume dose index (CTDIv), dose-length product (DLP), and effective dose were obtained using dose-length-product method. The obtained CTDIv, DLP, and effective dose were compared in two centers, and mean, maximum, and minimum values of effective dose for heart coronary CT angiography (CCTA) examinations and calcium score were compared with other studies. The amount of average, maximum, and minimum effective doses for heart CCTA examinations in two centers are 4.65 ± 0.06, 6.0489, and 3.492 mSv, respectively, and for calcium score test are, 1.04 ± 0.04, 2.155, and 0.98 mSv, respectively. CTDIv, DLP, and effective dose values did not show any significant difference in two centers. Although the effective dose of CTCA and calcium score was lower than that of other studies, it is reasonable to reduce the effective dose to the minimum possible value to reduce the risk of cancer associated with ionizing radiation. The results of this study can be used to introduce the effective dose as a local diagnostic reference dose (DRL) for CTCA examinations in Isfahan Province.

Approach towards re-irradiation of common cancers

Reirradiation, in combination with systemic therapy or biologicals, in recent years, has become a popular option for locally recurrent cancers and for infield second malignancies in cases where surgical salvage is not feasible. However before embarking onto such a course of second radiation a systematic approach is needed to avoid undesirable consequences and to gain meaningful advantage in terms of survival and local control. An decision making approach for common cancers where re-irradiation is commonly used like the head and neck cancers, the gliomas and in cases of gynecological cancers has been discussed. Proper selection of the cases and the choosing the intention for re-irradiation is probably most important initial step. Care of the details of the initials course of radiation like the dose fractionation schedule, volume irradiated, dose to the Organs at risk along with patient's present general condition is of utmost importance. Issues like dose memory, threshold time interval, maximum effective cumulative dose etc are still areas of research and their importance in each individual site needs to ascertain in future. Finally, the aim is to have a perceived benefit over the potential of harm in a successful course re-irradiation.

Neutron monitor count rate increase as a proxy for dose rate assessment at aviation altitudes during GLEs

Radiation exposure due to cosmic rays, specifically at cruising aviation altitudes, is an important topic in the field of space weather. While the effect of galactic cosmic rays can be easily assessed on the basis of recent models, estimate of the dose rate during strong solar particle events is rather complicated and time consuming. Here we compute the maximum effective dose rates at a typical commercial flight altitude of 35 kft (≈11 000 m above sea level) during ground level enhancement events, where the necessary information, namely derived energy/rigidity spectra of solar energetic particles, is available. The computations are carried out using different reconstructions of the solar proton spectra, available in bibliographic sources, leading to multiple results for some events. The computations were performed employing a recent model for effective dose and/or ambient dose equivalent due to cosmic ray particles. A conservative approach for the computation was assumed. A highly significant correlation between the maximum effective dose rate and peak NM count rate increase during ground level enhancement events is derived. Hence, we propose to use the peak NM count rate increase as a proxy in order to assess the peak effective dose rate at flight altitude during strong solar particle events using the real time records of the worldwide global neutron monitor network.

FAAH Inhibitor Improves Function of Inflamed Bladders by Modulation of Anandamide and Palmitoylethanolamide

Introduction: We aim to study the effect of fatty acid amide hydrolase (FAAH) blockade on bladder hyperactivity and on fatty acid amides levels during cystitis.&#x0D; Material and Methods: Cystitis was induced in female Wistar rats using 5 mg/mL lipopolysaccharide (LPS). Control group were intravesical instilled with saline. LPS and control groups received intravenously (caudal vein) during cystometry: URB 937 (URB; FAAH antagonist) in doses of 0.007, 0.07, 0.7 and 7 mg/kg (cumulative, with 10 minutes interval). Using the maximal effective dose of URB (0.7 mg/kg, see below) animals received 10 uM MJ15 (CB1 receptor antagonist) or 0.3 mg SR144528 /kg (SR; CB2 receptor antagonist). At dose of 7 mg/kg, animals receive 1.4 μg SB366791/kg (SB; TRPV1 antagonist). Control and inflamed (without and with 0.7 and 7 mg/kg URB) group were euthanized and the bladder was harvested for the determination of anandamide (AEA) and palmitoylethanolamide (PEA) by mass spectrometry.&#x0D; Results: Frequency of control was not changed by URB treatment at any dose. LPS increase bladder frequency. 0.007 mg and 0.07 mg URB decrease bladder frequency of LPS-inflamed rats. 0.7 URB reversed LPS-induced bladder hyperactivity. At 7 mg, URB was unable to reverse or reduce LPS-induced bladder hyperactivity. The administration of CB1, CB2 and TRPV1 antagonists did not change the frequency of voiding contractions of naïve animals. CB1 antagonist reversed the effect of 0.7 URB while TRPV1 antagonist reduced the effect of 7 URB. AEA levels increase during inflammation. Treating LPS-inflamed animals with 0.7 mg URB brought AEA levels to control levels. Treating LPS-inflamed animals with 7 mg URB did not change AEA levels, compared to LPS-inflamed animals. PEA levels decrease during inflammation. Treating LPS-inflamed animals with 0.7 mg URB brought AEA levels to control levels. Treating LPS-inflamed animals with 7 mg URB, decreased PEA levels to values similar to the ones observed in LPS- -inflamed animals.&#x0D; Conclusion: During cystitis, the FAAH inhibitor raises the levels of PEA and reverses the urinary frequency by a CB1 receptor- mediated mechanism. When used in very high doses, the FAAH antagonist raises the levels of AEA and increases the urinary frequency by a TRPV1-dependent mechanism. Therefore, the choice of FAAH inhibitor dosage to be used in the clinics should consider the putative effects over the endocannabinoid levels in the system.

Assessment of Occupational Exposure to External Radiation among Workers at the Institute of Radiotherapy and Nuclear Medicine, Pakistan (2009-2016)

Introduction: Assessment of occupational exposure to external radiation and the analysis of associated trends are imperative to observe changes that have taken place over time due to regulatory operations or technological advancements. Herein, we describe the occupational radiation exposure to workers employed in Nuclear Medicine (NM), Radiotherapy (RT), and Diagnostic Radiology (DR) departments at the Institute of Radiotherapy and Nuclear Medicine, Peshawar, Pakistan, and to evaluate the related trends during 2009-2016. Materials and Methods: A retrospective analysis of the dose records of 4320 film dosimeters was performed during 2009-2016. The analyzed quantities included annual collective effective dose, annual average effective dose, distribution of workers, and their annual average effective doses in various effective dose intervals, as well as the maximum and minimum annual individual effective doses. Results: The annual average effective doses in RT, NM, and DR were within the ranges of 1.07-1.45, 1.25-1.55, and 1.03-1.60 mSv, respectively. The majority (90%) of the workers received effective doses in the interval of 1-4.99 mSv, while 10% of the workers received doses within the range of the minimum detectable level-0.99 mSv. The minimum and maximum annual individual effective doses were 0.30 mSv and 3.96 mSv as recorded in RT and NM, respectively. The annual average effective doses measured for NM, RT, and DR were 1.39, 1.23, and 1.30 mSv, respectively. These values are comparable with the worldwide annual average effective doses. Conclusion: All the workers received doses below the annual dose limit. The status and trends of doses showed that radiation protection conditions were adequate.

Dexmedetomidine as a neuraxial adjuvant for prevention of perioperative shivering: Meta-analysis of randomized controlled trials.

BackgroundDexmedetomidine, a highly selective α2-adrenoceptor agonist, has been investigated for anti-shivering effects in some trials. This current meta-analysis was conducted to evaluate the effectiveness of dexmedetomidine as a neuraxial adjuvant in preventing perioperative shivering.MethodsThis systematic review and meta-analysis was registered in PROSPERO [www.crd.york.ac.uk/PROSPERO] with the unique identification number CRD42017055991. The electronic databases PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL) were searched to select high-quality randomized controlled trials (RCTs) that evaluated the anti-shivering efficacy for neuraxial application dexmedetomidine as local anesthetic adjuvant. Effects were summarized using pooled risk ratios (RRs), weighed mean differences (MDs), or standardized mean differences (SMDs) and corresponding 95% confidence intervals (Cls) with random effect model. Heterogeneity assessment, sensitivity analysis, and publication bias were performed. The primary outcome was perioperative shivering.ResultsA total of 1760 patients from 24 studies were included in this meta-analysis. Compared with the placebo, dexmedetomidine reduced the incidence of perioperative shivering (RR: 0.34; 95% Cl: 0.21 to 0.55; P < 0.00001), with a maximum effective dose of 5μg via subarachnoid space injection (RR: 0.55; 95% CI: 0.32 to 0.92; P = 0.02), especially in cesarean section (RR: 0.20; 95% CI: 0.09 to 0.45; P = 0.0001). Dexmedetomidine also could improve the characteristics of the block, with an increase only in the incidence of bradycardia (RR: 2.11; 95% CI: 1.23 to 3.60; P = 0.006). No significant difference could be found compared dexmedetomidine with other adjuvants, except morphine.ConclusionsThis meta-analysis shows that dexmedetomidine as a neuraxial adjuvant had statistically significant efficacy on prevention of perioperative shivering. Moreover, dexmedetomidine could improve the characteristics of the block. However, the potential induction of bradycardia should be taken seriously.