Shot sequencing based on biological equivalent dose considerations for multiple isocenter Gamma Knife radiosurgery

NASA Astrophysics Data System (ADS)

Ma, Lijun; Lee, Letitia; Barani, Igor; Hwang, Andrew; Fogh, Shannon; Nakamura, Jean; McDermott, Michael; Sneed, Penny; Larson, David A.; Sahgal, Arjun

2011-11-01

Rapid delivery of multiple shots or isocenters is one of the hallmarks of Gamma Knife radiosurgery. In this study, we investigated whether the temporal order of shots delivered with Gamma Knife Perfexion would significantly influence the biological equivalent dose for complex multi-isocenter treatments. Twenty single-target cases were selected for analysis. For each case, 3D dose matrices of individual shots were extracted and single-fraction equivalent uniform dose (sEUD) values were determined for all possible shot delivery sequences, corresponding to different patterns of temporal dose delivery within the target. We found significant variations in the sEUD values among these sequences exceeding 15% for certain cases. However, the sequences for the actual treatment delivery were found to agree (<3%) and to correlate (R2 = 0.98) excellently with the sequences yielding the maximum sEUD values for all studied cases. This result is applicable for both fast and slow growing tumors with α/β values of 2 to 20 according to the linear-quadratic model. In conclusion, despite large potential variations in different shot sequences for multi-isocenter Gamma Knife treatments, current clinical delivery sequences exhibited consistent biological target dosing that approached that maximally achievable for all studied cases.

Three-Dimensional Radiobiologic Dosimetry: Application of Radiobiologic Modeling to Patient-Specific 3-Dimensional Imaging–Based Internal Dosimetry

PubMed Central

Prideaux, Andrew R.; Song, Hong; Hobbs, Robert F.; He, Bin; Frey, Eric C.; Ladenson, Paul W.; Wahl, Richard L.; Sgouros, George

2010-01-01

Phantom-based and patient-specific imaging-based dosimetry methodologies have traditionally yielded mean organ-absorbed doses or spatial dose distributions over tumors and normal organs. In this work, radiobiologic modeling is introduced to convert the spatial distribution of absorbed dose into biologically effective dose and equivalent uniform dose parameters. The methodology is illustrated using data from a thyroid cancer patient treated with radioiodine. Methods Three registered SPECT/CT scans were used to generate 3-dimensional images of radionuclide kinetics (clearance rate) and cumulated activity. The cumulated activity image and corresponding CT scan were provided as input into an EGSnrc-based Monte Carlo calculation: The cumulated activity image was used to define the distribution of decays, and an attenuation image derived from CT was used to define the corresponding spatial tissue density and composition distribution. The rate images were used to convert the spatial absorbed dose distribution to a biologically effective dose distribution, which was then used to estimate a single equivalent uniform dose for segmented volumes of interest. Equivalent uniform dose was also calculated from the absorbed dose distribution directly. Results We validate the method using simple models; compare the dose-volume histogram with a previously analyzed clinical case; and give the mean absorbed dose, mean biologically effective dose, and equivalent uniform dose for an illustrative case of a pediatric thyroid cancer patient with diffuse lung metastases. The mean absorbed dose, mean biologically effective dose, and equivalent uniform dose for the tumor were 57.7, 58.5, and 25.0 Gy, respectively. Corresponding values for normal lung tissue were 9.5, 9.8, and 8.3 Gy, respectively. Conclusion The analysis demonstrates the impact of radiobiologic modeling on response prediction. The 57% reduction in the equivalent dose value for the tumor reflects a high level of dose nonuniformity in the tumor and a corresponding reduced likelihood of achieving a tumor response. Such analyses are expected to be useful in treatment planning for radionuclide therapy. PMID:17504874

Thermally assisted OSL application for equivalent dose estimation; comparison of multiple equivalent dose values as well as saturation levels determined by luminescence and ESR techniques for a sedimentary sample collected from a fault gouge

NASA Astrophysics Data System (ADS)

Şahiner, Eren; Meriç, Niyazi; Polymeris, George S.

2017-02-01

Equivalent dose estimation (De) constitutes the most important part of either trap-charge dating techniques or dosimetry applications. In the present work, multiple, independent equivalent dose estimation approaches were adopted, using both luminescence and ESR techniques; two different minerals were studied, namely quartz as well as feldspathic polymineral samples. The work is divided into three independent parts, depending on the type of signal employed. Firstly, different De estimation approaches were carried out on both polymineral and contaminated quartz, using single aliquot regenerative dose protocols employing conventional OSL and IRSL signals, acquired at different temperatures. Secondly, ESR equivalent dose estimations using the additive dose procedure both at room temperature and at 90 K were discussed. Lastly, for the first time in the literature, a single aliquot regenerative protocol employing a thermally assisted OSL signal originating from Very Deep Traps was applied for natural minerals. Rejection criteria such as recycling and recovery ratios are also presented. The SAR protocol, whenever applied, provided with compatible De estimations with great accuracy, independent on either the type of mineral or the stimulation temperature. Low temperature ESR signals resulting from Al and Ti centers indicate very large De values due to bleaching in-ability, associated with large uncertainty values. Additionally, dose saturation of different approaches was investigated. For the signal arising from Very Deep Traps in quartz saturation is extended almost by one order of magnitude. It is interesting that most of De values yielded using different luminescence signals agree with each other and ESR Ge center has very large D0 values. The results presented above highly support the argument that the stability and the initial ESR signal of the Ge center is highly sample-dependent, without any instability problems for the cases of quartz resulting from fault gouge.

Method for measuring dose-equivalent in a neutron flux with an unknown energy spectra and means for carrying out that method

DOEpatents

Distenfeld, Carl H.

1978-01-01

A method for measuring the dose-equivalent for exposure to an unknown and/or time varing neutron flux which comprises simultaneously exposing a plurality of neutron detecting elements of different types to a neutron flux and combining the measured responses of the various detecting elements by means of a function, whose value is an approximate measure of the dose-equivalent, which is substantially independent of the energy spectra of the flux. Also, a personnel neutron dosimeter, which is useful in carrying out the above method, comprising a plurality of various neutron detecting elements in a single housing suitable for personnel to wear while working in a radiation area.

Influence of beam efficiency through the patient-specific collimator on secondary neutron dose equivalent in double scattering and uniform scanning modes of proton therapy.

PubMed

Hecksel, D; Anferov, V; Fitzek, M; Shahnazi, K

2010-06-01

Conventional proton therapy facilities use double scattering nozzles, which are optimized for delivery of a few fixed field sizes. Similarly, uniform scanning nozzles are commissioned for a limited number of field sizes. However, cases invariably occur where the treatment field is significantly different from these fixed field sizes. The purpose of this work was to determine the impact of the radiation field conformity to the patient-specific collimator on the secondary neutron dose equivalent. Using a WENDI-II neutron detector, the authors experimentally investigated how the neutron dose equivalent at a particular point of interest varied with different collimator sizes, while the beam spreading was kept constant. The measurements were performed for different modes of dose delivery in proton therapy, all of which are available at the Midwest Proton Radiotherapy Institute (MPRI): Double scattering, uniform scanning delivering rectangular fields, and uniform scanning delivering circular fields. The authors also studied how the neutron dose equivalent changes when one changes the amplitudes of the scanned field for a fixed collimator size. The secondary neutron dose equivalent was found to decrease linearly with the collimator area for all methods of dose delivery. The relative values of the neutron dose equivalent for a collimator with a 5 cm diameter opening using 88 MeV protons were 1.0 for the double scattering field, 0.76 for rectangular uniform field, and 0.6 for the circular uniform field. Furthermore, when a single circle wobbling was optimized for delivery of a uniform field 5 cm in diameter, the secondary neutron dose equivalent was reduced by a factor of 6 compared to the double scattering nozzle. Additionally, when the collimator size was kept constant, the neutron dose equivalent at the given point of interest increased linearly with the area of the scanned proton beam. The results of these experiments suggest that the patient-specific collimator is a significant contributor to the secondary neutron dose equivalent to a distant organ at risk. Improving conformity of the radiation field to the patient-specific collimator can significantly reduce secondary neutron dose equivalent to the patient. Therefore, it is important to increase the number of available generic field sizes in double scattering systems as well as in uniform scanning nozzles.

NAIRAS aircraft radiation model development, dose climatology, and initial validation.

PubMed

Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

2013-10-01

[1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway.

NAIRAS aircraft radiation model development, dose climatology, and initial validation

NASA Astrophysics Data System (ADS)

Mertens, Christopher J.; Meier, Matthias M.; Brown, Steven; Norman, Ryan B.; Xu, Xiaojing

2013-10-01

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway.

NAIRAS aircraft radiation model development, dose climatology, and initial validation

PubMed Central

Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

2013-01-01

[1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway. PMID:26213513

Single oral dose of 1-5g. talampicillin in the treatment of gonorrhoea.

PubMed Central

Willcox, R R

1976-01-01

81 patients have been treated with single oral doses of 1-5 g. (6 tablets) of talampicillin without probenecid. The failure rate amongst those followed was only 4-2 per cent. No side-effects were reported. These results were superior to those obtained with 2-0g. or equivalent of ampicillin, amoxycillin, or pivampicillin with probenecid. Talampicillin is thus the most potent ampicillin-like antibiotic so far available for the treatment of gonorrhoea and is capable of curing the disease with a smaller single dose without probenecid than is necessary for other preparations. PMID:1276866

Gastrografin in acute meconium ileus equivalent.

PubMed Central

O'Halloran, S M; Gilbert, J; McKendrick, O M; Carty, H M; Heaf, D P

1986-01-01

Twenty-five (37%) patients with cystic fibrosis attending our clinic have experienced acute meconium ileus equivalent. In one year 37 of 40 episodes were treated with single dose oral Gastrografin with an 81% success rate, 75% being treated as outpatients. Patients found this treatment preferable to other recommended treatment. PMID:3789794

The impact of inter-fraction dose variations on biological equivalent dose (BED): the concept of equivalent constant dose.

PubMed

Zavgorodni, S

2004-12-07

Inter-fraction dose fluctuations, which appear as a result of setup errors, organ motion and treatment machine output variations, may influence the radiobiological effect of the treatment even when the total delivered physical dose remains constant. The effect of these inter-fraction dose fluctuations on the biological effective dose (BED) has been investigated. Analytical expressions for the BED accounting for the dose fluctuations have been derived. The concept of biological effective constant dose (BECD) has been introduced. The equivalent constant dose (ECD), representing the constant physical dose that provides the same cell survival fraction as the fluctuating dose, has also been introduced. The dose fluctuations with Gaussian as well as exponential probability density functions were investigated. The values of BECD and ECD calculated analytically were compared with those derived from Monte Carlo modelling. The agreement between Monte Carlo modelled and analytical values was excellent (within 1%) for a range of dose standard deviations (0-100% of the dose) and the number of fractions (2 to 37) used in the comparison. The ECDs have also been calculated for conventional radiotherapy fields. The analytical expression for the BECD shows that BECD increases linearly with the variance of the dose. The effect is relatively small, and in the flat regions of the field it results in less than 1% increase of ECD. In the penumbra region of the 6 MV single radiotherapy beam the ECD exceeded the physical dose by up to 35%, when the standard deviation of combined patient setup/organ motion uncertainty was 5 mm. Equivalently, the ECD field was approximately 2 mm wider than the physical dose field. The difference between ECD and the physical dose is greater for normal tissues than for tumours.

The application of drug dose equivalence in the quantitative analysis of receptor occupation and drug combinations

PubMed Central

Tallarida, Ronald J.; Raffa, Robert B.

2014-01-01

In this review we show that the concept of dose equivalence for two drugs, the theoretical basis of the isobologram, has a wider use in the analysis of pharmacological data derived from single and combination drug use. In both its application to drug combination analysis with isoboles and certain other actions, listed below, the determination of doses, or receptor occupancies, that yield equal effects provide useful metrics that can be used to obtain quantitative information on drug actions without postulating any intimate mechanism of action. These other drug actions discussed here include (1) combinations of agonists that produce opposite effects, (2) analysis of inverted U-shaped dose effect curves of single agents, (3) analysis on the effect scale as an alternative to isoboles and (4) the use of occupation isoboles to examine competitive antagonism in the dual receptor case. New formulas derived to assess the statistical variance for additive combinations are included, and the more detailed mathematical topics are included in the appendix. PMID:20546783

Comparison of Diagnostic Accuracy of Radiation Dose-Equivalent Radiography, Multidetector Computed Tomography and Cone Beam Computed Tomography for Fractures of Adult Cadaveric Wrists

PubMed Central

Neubauer, Jakob; Benndorf, Matthias; Reidelbach, Carolin; Krauß, Tobias; Lampert, Florian; Zajonc, Horst; Kotter, Elmar; Langer, Mathias; Fiebich, Martin; Goerke, Sebastian M.

2016-01-01

Purpose To compare the diagnostic accuracy of radiography, to radiography equivalent dose multidetector computed tomography (RED-MDCT) and to radiography equivalent dose cone beam computed tomography (RED-CBCT) for wrist fractures. Methods As study subjects we obtained 10 cadaveric human hands from body donors. Distal radius, distal ulna and carpal bones (n = 100) were artificially fractured in random order in a controlled experimental setting. We performed radiation dose equivalent radiography (settings as in standard clinical care), RED-MDCT in a 320 row MDCT with single shot mode and RED-CBCT in a device dedicated to musculoskeletal imaging. Three raters independently evaluated the resulting images for fractures and the level of confidence for each finding. Gold standard was evaluated by consensus reading of a high-dose MDCT. Results Pooled sensitivity was higher in RED-MDCT with 0.89 and RED-MDCT with 0.81 compared to radiography with 0.54 (P = < .004). No significant differences were detected concerning the modalities’ specificities (with values between P = .98). Raters' confidence was higher in RED-MDCT and RED-CBCT compared to radiography (P < .001). Conclusion The diagnostic accuracy of RED-MDCT and RED-CBCT for wrist fractures proved to be similar and in some parts even higher compared to radiography. Readers are more confident in their reporting with the cross sectional modalities. Dose equivalent cross sectional computed tomography of the wrist could replace plain radiography for fracture diagnosis in the long run. PMID:27788215

Safety, Tolerability, and Pharmacokinetic Properties of Intravenous Delafloxacin After Single and Multiple Doses in Healthy Volunteers.

PubMed

Hoover, Randall; Hunt, Thomas; Benedict, Michael; Paulson, Susan K; Lawrence, Laura; Cammarata, Sue; Sun, Eugene

2016-01-01

The objective of this report was to determine the pharmacokinetic properties, safety, and tolerability of single and multiple doses of intravenous delafloxacin. In addition, the absolute bioavailability (BA) of the 450-mg tablet formulation of delafloxacin was determined. Three clinical trials are summarized. The first study was a randomized, double-blind, placebo-controlled, single- (300, 450, 600, 750, 900, and 1200 mg) ascending-dose study of IV delafloxacin in 62 (52 active, 10 placebo) healthy volunteers. The second study was a randomized, double-blind, placebo-controlled study of IV delafloxacin (300 mg) given as a single dose on day 1, followed by twice-daily dosing on days 2 through 14; 12 (8 active, 4 placebo) healthy volunteers were enrolled. The third study was an open-label, randomized, 2-period, 2-sequence crossover study in which 56 healthy volunteers were randomly assigned to 1 of 2 sequences of a single oral dose of delafloxacin (450-mg tablet) or IV delafloxacin (300 mg). Serial blood samples were collected, and plasma pharmacokinetic parameters of delafloxacin were calculated. Delafloxacin Cmax values increased proportionally with increasing single IV dose for the dose range of 300 to 1200 mg, whereas the AUC values increased more than proportionally to dose for the same dose range. The mean terminal half-life of delafloxacin was approximately 12 hours (ranging from 8 to 17 hours). The volume of distribution (Vd) at steady state was approximately 35 L, which is similar to the volume of total body water. There was minimal accumulation of delafloxacin after twice-daily IV administration of 300 mg with an accumulation ratio of 1.09. The delafloxacin total exposure after a single 1-hour IV infusion of 300 mg and a single oral dose of a 450-mg tablet were equivalent with geometric least square mean ratio (90% CI) of 0.8768 (0.8356-0.9200) for AUC0-∞ and 0.8445 (0.8090-0.8815) for AUC0-t, respectively. The Cmax values of delafloxacin were not equivalent for the 2 formulations with a ratio (90% CI) of 0.5516 (0.5150-0.5908), respectively. The mean absolute bioavailability of delafloxacin was 58.8%. Delafloxacin was well tolerated in healthy volunteers after single and multiple IV doses. The total systemic exposure to IV (300 mg) and oral (450 mg) delafloxacin is comparable, supporting that a switch between the 2 formulations is appropriate. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Equivalence of Gyn GEC-ESTRO guidelines for image guided cervical brachytherapy with EUD-based dose prescription

PubMed Central

2013-01-01

Background To establish a generalized equivalent uniform dose (gEUD) -based prescription method for Image Guided Brachytherapy (IGBT) that reproduces the Gyn GEC-ESTRO WG (GGE) prescription for cervix carcinoma patients on CT images with limited soft tissue resolution. Methods The equivalence of two IGBT planning approaches was investigated in 20 patients who received external beam radiotherapy (EBT) and 5 concomitant high dose rate IGBT treatments. The GGE planning strategy based on dose to the most exposed 2 cm3 (D2cc) was used to derive criteria for the gEUD-based planning of the bladder and rectum. The safety of gEUD constraints in terms of GGE criteria was tested by maximizing dose to the gEUD constraints for individual fractions. Results The gEUD constraints of 3.55 Gy for the rectum and 5.19 Gy for the bladder were derived. Rectum and bladder gEUD-maximized plans resulted in D2cc averages very similar to the initial GGE criteria. Average D2ccs and EUDs from the full treatment course were comparable for the two techniques within both sets of normal tissue constraints. The same was found for the tumor doses. Conclusions The derived gEUD criteria for normal organs result in GGE-equivalent IGBT treatment plans. The gEUD-based planning considers the entire dose distribution of organs in contrast to a single dose-volume-histogram point. PMID:24225184

Luminescence (IRSL) dating of Yeni Rabat church in Artvin, Turkey

NASA Astrophysics Data System (ADS)

Şahiner, Eren; Meriç, Niyazi; Uygun, Selda

2013-05-01

Luminescence dating is a chronological method that has been used extensively in terrestrial materials. In this study, we present Infrared Stimulated Luminescence (IRSL) dating results obtained for sediment and pottery samples taken from Yeni Rabat Church, Ardanuç, Artvin, Turkey. For this purpose, equivalent dose (ED) and annual dose rate (AD) of samples were measured. For annual dose rate, concentrations of radioactive isotopes (U, Th, K) were determined by using a high-purity germanium detector. For the equivalent dose, polymineral fine grain SAR (Single Aliquot Regenerative Dose) and MAAD (Multiple Aliquot Additive Dose) procedures were used. The optimal preheat temperature was determined for sediment and pottery samples. Ages were calculated by Aitken's luminescence age calculation method, which found 710±190 years for the pottery sample and 1450±370 years, 1390±420 years, 1430±310 years, 2210±520 years and 1640±390 years for different sediment samples, respectively. These estimated age ranges support the theory that Yeni Rabat Church could have been constructed in medieval times.

SU-E-T-248: An Extended Generalized Equivalent Uniform Dose Accounting for Dose-Range Dependency of Radio-Biological Parameters.

PubMed

Troeller, A; Soehn, M; Yan, D

2012-06-01

Introducing an extended, phenomenological, generalized equivalent uniform dose (eEUD) that incorporates multiple volume-effect parameters for different dose-ranges. The generalized EUD (gEUD) was introduced as an estimate of the EUD that incorporates a single, tissue-specific parameter - the volume-effect-parameter (VEP) 'a'. As a purely phenomenological concept, its radio-biological equivalency to a given inhomogeneous dose distribution is not a priori clear and mechanistic models based on radio-biological parameters are assumed to better resemble the underlying biology. However, for normal organs mechanistic models are hard to derive, since the structural organization of the tissue plays a significant role. Consequently, phenomenological approaches might be especially useful in order to describe dose-response for normal tissues. However, the single parameter used to estimate the gEUD may not suffice in accurately representing more complex biological effects that have been discussed in the literature. For instance, radio-biological parameters and hence the effects of fractionation are known to be dose-range dependent. Therefore, we propose an extended phenomenological eEUD formula that incorporates multiple VEPs accounting for dose-range dependency. The eEUD introduced is a piecewise polynomial expansion of the gEUD formula. In general, it allows for an arbitrary number of VEPs, each valid for a certain dose-range. We proved that the formula fulfills required mathematical and physical criteria such as invertibility of the underlying dose-effect and continuity in dose. Furthermore, it contains the gEUD as a special case, if all VEPs are equal to 'a' from the gEUD model. The eEUD is a concept that expands the gEUD such that it can theoretically represent dose-range dependent effects. Its practicality, however, remains to be shown. As a next step, this will be done by estimating the eEUD from patient data using maximum-likelihood based NTCP modelling in the same way it is commonly done for the gEUD. © 2012 American Association of Physicists in Medicine.

Comparison of plan quality and delivery time between volumetric arc therapy (RapidArc) and Gamma Knife radiosurgery for multiple cranial metastases.

PubMed

Thomas, Evan M; Popple, Richard A; Wu, Xingen; Clark, Grant M; Markert, James M; Guthrie, Barton L; Yuan, Yu; Dobelbower, Michael C; Spencer, Sharon A; Fiveash, John B

2014-10-01

Volumetric modulated arc therapy (VMAT) has been shown to be feasible for radiosurgical treatment of multiple cranial lesions with a single isocenter. To investigate whether equivalent radiosurgical plan quality and reduced delivery time could be achieved in VMAT for patients with multiple intracranial targets previously treated with Gamma Knife (GK) radiosurgery. We identified 28 GK treatments of multiple metastases. These were replanned for multiarc and single-arc, single-isocenter VMAT (RapidArc) in Eclipse. The prescription for all targets was standardized to 18 Gy. Each plan was normalized for 100% prescription dose to 99% to 100% of target volume. Plan quality was analyzed by target conformity (Radiation Therapy Oncology Group and Paddick conformity indices [CIs]), dose falloff (area under the dose-volume histogram curve), as well as the V4.5, V9, V12, and V18 isodose volumes. Other end points included beam-on and treatment time. Compared with GK, multiarc VMAT improved median plan conformity (CIVMAT = 1.14, CIGK = 1.65; P < .001) with no significant difference in median dose falloff (P = .269), 12 Gy isodose volume (P = .500), or low isodose spill (P = .49). Multiarc VMAT plans were associated with markedly reduced treatment time. A predictive model of the 12 Gy isodose volume as a function of tumor number and volume was also developed. For multiple target stereotactic radiosurgery, 4-arc VMAT produced clinically equivalent conformity, dose falloff, 12 Gy isodose volume, and low isodose spill, and reduced treatment time compared with GK. Because of its similar plan quality and increased delivery efficiency, single-isocenter VMAT radiosurgery may constitute an attractive alternative to multi-isocenter radiosurgery for some patients.

A study of surface dosimetry for breast cancer radiotherapy treatments using Gafchromic EBT2 film

PubMed Central

Hill, Robin F.; Whitaker, May; Kim, Jung‐Ha; Kuncic, Zdenka

2012-01-01

The present study quantified surface doses on several rectangular phantom setups and on curved surface phantoms for a 6 MV photon field using the Attix parallel‐plate chamber and Gafchromic EBT2 film. For the rectangular phantom setups, the surface doses on a homogenous water equivalent phantom and a water equivalent phantom with 60 mm thick lung equivalent material were measured. The measurement on the homogenous phantom setup showed consistency in surface and near‐surface doses between an open field and enhanced dynamic wedge (EDW) fields, whereas physical wedged fields showed small differences. Surface dose measurements made using the EBT2 film showed good agreement with results of the Attix chamber and results obtained in previous studies which used other dosimeters within the measurement uncertainty of 3.3%. The surface dose measurements on the phantom setup with lung equivalent material showed a small increase without bolus and up to 6.9% increase with bolus simulating the increase of chest wall thickness. Surface doses on the cylindrical CT phantom and customized Perspex chest phantom were measured using the EBT2 film with and without bolus. The results indicate the important role of the presence of bolus if the clinical target volume (CTV) is quite close to the surface. Measurements on the cylindrical phantom suggest that surface doses at the oblique positions of 60° and 90° are mainly caused by the lateral scatter from the material inside the phantom. In the case of a single tangential irradiation onto Perspex chest phantom, the distribution of the surface dose with and without bolus materials showed opposing inclination patterns, whereas the dose distribution for two opposed tangential fields gave symmetric dose distribution. This study also demonstrates the suitability of Gafchromic EBT2 film for surface dose measurements in megavoltage photon beams. PACS number: 87.53.Bn PMID:22584169

Bioequivalence of fixed-dose combination RIN®-150 to each reference drug in loose combination.

PubMed

Wang, H F; Wang, R; O'Gorman, M; Crownover, P; Damle, B

2015-03-01

RIN(®)-150 is a fixed-dose combination (FDC) tablet containing rifampicin (RMP, 150 mg) and isoniazid (INH, 75 mg) developed for the treatment of tuberculosis. This study was conducted at a single center: the Pfizer Clinical Research Unit in Singapore. To demonstrate bioequivalence of each drug component between RIN-150 and individual products in a loose combination. This was a randomized, open-label, single-dose, two-way crossover study. Subjects received single doses of RIN-150 or two individual reference products under fasting conditions in a crossover fashion, with at least 7 days washout between doses. The primary measures for comparison were peak plasma concentration (Cmax) and the area under plasma concentration-time curve (AUC). Of 28 subjects enrolled, 26 completed the study. The adjusted geometric mean ratios of Cmax and AUClast between the FDC and single-drug references and 90% confidence intervals were respectively 91.63% (90%CI 83.13-101.01) and 95.45% (90%CI 92.07-98.94) for RMP, and 107.58% (90%CI 96.07-120.47) and 103.45% (90%CI 99.33-107.75) for INH. Both formulations were generally well tolerated in this study. The RIN-150 FDC tablet formulation is bioequivalent to the two single-drug references for RMP and INH at equivalent doses.

Hydration and transparency of the rabbit cornea irradiated with UVB-doses of 0.25 J/cm(2) and 0.5 J/cm(2) compared with equivalent UVB radiation exposure reaching the human cornea from sunlight.

PubMed

Cejka, Cestmír; Ardan, Taras; Sirc, Jakub; Michálek, Jiří; Beneš, Jiří; Brůnová, Blanka; Rosina, Jozef

2011-07-01

Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight. Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm(2) or 0.5 J/cm(2) for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals. Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm(2) and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm(2). The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm(2). Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection.

Delivery of fenoterol via Respimat, a novel 'soft mist' inhaler. a randomised, double-blind (within device), placebo-controlled, cross-over, dose-ranging study in asthmatic patients.

PubMed

van Noord, J A; Smeets, J J; Creemers, J P; Greefhorst, L P; Dewberry, H; Cornelissen, P J

2000-01-01

The phase-out of chlorofluorocarbons (CFCs) for metered dose inhalers (MDIs) has prompted the development of alternative propellants and the design of propellant-free devices for inhalation therapy. This study was carried out to determine the dose of fenoterol inhaled from Respimat (RMT), a new propellant-free soft mist inhaler, which is equivalent in terms of efficacy and safety to 1 puff of either 100 or 200 microg fenoterol inhaled from a conventional CFC-MDI (Berotec). Sixty-two asthmatic patients (35 male, 27 female) with a mean baseline FEV(1) of 1.7 liters, corresponding to 55% of the predicted normal value, were randomized at two study centers to 4 of a total of 8 possible treatments: placebo; 12.5, 25, 50, 100, or 200 microg fenoterol via RMT, and 100 or 200 microg fenoterol delivered via the MDI. Fifty-nine patients completed the study as planned. Results of the therapeutic equivalence test for the primary endpoint, average FEV(1) (AUC(0-6))/6 and for the secondary endpoint, peak FEV(1), showed that the 12.5- and 25-microg fenoterol doses administered via RMT were equivalent to the 100 microg fenoterol dose from the MDI. The 50-, 100- and 200-microg fenoterol doses delivered by RMT did not meet the criterion for therapeutic equivalence with the 100-microg dose from the MDI, and if tested for a difference would have been significantly different in favor of RMT. All 5 RMT fenoterol doses were therapeutically equivalent to the MDI 200-microg fenoterol dose. Headache, reported by 4 patients on test days and 2 patients between test days in those randomized to RMT, was the most common adverse event, but the active treatments were generally well tolerated with no dose-dependent increases in incidence or severity of adverse events observed. The results from the study suggest that safe and efficacious bronchodilation can be obtained from single-dose fenoterol administered via RMT. Use of lower absolute doses to obtain a clinically significant improvement in pulmonary function may be possible because of the increased lung deposition achievable with the novel soft mist inhaler. Copyright 2000 S. Karger AG, Basel

Pharmacokinetics of pregabalin controlled-release in healthy volunteers: effect of food in five single-dose, randomized, clinical pharmacology studies.

PubMed

Chew, Marci L; Plotka, Anna; Alvey, Christine W; Pitman, Verne W; Alebic-Kolbah, Tanja; Scavone, Joseph M; Bockbrader, Howard N

2014-09-01

The pharmacokinetic properties of the immediate-release (IR) and the recently developed controlled-release (CR) formulation of pregabalin are dose proportional. Pregabalin IR can be taken with or without food. This analysis characterizes the effect of food on pregabalin CR. The objectives of this analysis were: (1) to evaluate the effect of administration time and fat or caloric content of an accompanying meal on the pharmacokinetic properties of a single dose of pregabalin CR (330 mg) relative to a single dose of pregabalin IR (300 mg); (2) to evaluate the pharmacokinetic properties of a single dose of pregabalin CR administered fasted relative to a single dose of pregabalin CR administered immediately after food; and (3) to determine the safety and tolerability of single-dose administration of pregabalin CR and IR with and without food. The effect of food on the pharmacokinetic properties of pregabalin CR was determined in five phase I, open-label, single-dose, crossover studies (24-28 participants/study). Caloric and fat content of meals were varied and treatments were administered in the morning, at midday, or in the evening. Blood samples were collected up to 48 h post-dose. Pharmacokinetic parameters were estimated from plasma concentration-time data using standard noncompartmental methods. Adverse events were monitored throughout all studies. One hundred and twenty-eight healthy participants (19-54 years of age) received pregabalin. Peak plasma concentrations (C max) were lower for CR than the respective pregabalin IR doses, and time to C max occurred later. When pregabalin CR was administered with food at midday or in the evening, total exposures [area under the plasma concentration-time curve from time zero extrapolated to infinite time (AUC∞)] were equivalent for pregabalin CR and IR formulations regardless of fat or caloric content. When pregabalin CR was administered with an 800-1,000 calorie medium-fat breakfast, AUC∞ was equivalent for pregabalin CR and IR. Bioequivalence criteria for comparison of pregabalin CR after a low- or medium-calorie breakfast relative to pregabalin IR were not met; however, bioavailability of the pregabalin CR vs. IR formulation was relatively high (75-86 %). When pregabalin CR was administered fasted, the AUC∞ was 70-78 % of the AUC∞ of pregabalin CR administered with food and bioequivalence criteria were not met. Additionally, the AUC∞ of the pregabalin CR formulation administered fasted was 62-69 % of that of pregabalin IR administered fasted and bioequivalence criteria were not met. Single-dose pregabalin CR and IR were well tolerated in all studies, with no serious or severe adverse events reported. Time of day of administration and the fat and caloric content of the accompanying meal had minimal overall effect on the pharmacokinetic properties and bioavailability of the pregabalin CR formulation.

Hazards to animals feeding on blackbirds killed with 4-aminopyridine baits

USGS Publications Warehouse

Schafer, E.W.; Brunton, R.B.; Lockyer, Norman F.

1974-01-01

Red-winged blackbirds (Agelaius phoeniceus) killed by ingesting cracked corn baits treated with 3 percent 4-aminopyridine, or by oral doses of 4-aminopyridine, were fed to canines, laboratory rats (Rattus norvegicus), black-billed magpies (Pica pica), and three species of hawks. The test animals consumed the equivalent of up to 3.4 LD50 doses of 4-aminopyridine in single feedings and up to 3.2 LD50 doses a day for 20 days in repeated feedings. None showed any symptoms of intoxication or gross abnormalities at necropsy.

Canakinumab reduces the risk of acute gouty arthritis flares during initiation of allopurinol treatment: results of a double-blind, randomised study

PubMed Central

Schlesinger, Naomi; Mysler, Eduardo; Lin, Hsiao-Yi; De Meulemeester, Marc; Rovensky, Jozef; Arulmani, Udayasankar; Balfour, Alison; Krammer, Gerhard; Sallstig, Peter; So, Alexander

2011-01-01

Objective This study assessed the efficacy and safety of canakinumab, a fully human anti-interleukin 1β monoclonal antibody, for prophylaxis against acute gouty arthritis flares in patients initiating urate-lowering treatment. Methods In this double-blind, double-dummy, dose-ranging study, 432 patients with gouty arthritis initiating allopurinol treatment were randomised 1:1:1:1:1:1:2 to receive: a single dose of canakinumab, 25, 50, 100, 200, or 300 mg subcutaneously; 4×4-weekly doses of canakinumab (50+50+25+25 mg subcutaneously); or daily colchicine 0.5 mg orally for 16 weeks. Patients recorded details of flares in diaries. The study aimed to determine the canakinumab dose having equivalent efficacy to colchicine 0.5 mg at 16 weeks. Results A dose-response for canakinumab was not apparent with any of the four predefined dose-response models. The estimated canakinumab dose with equivalent efficacy to colchicine was below the range of doses tested. At 16 weeks, there was a 62% to 72% reduction in the mean number of flares per patient for canakinumab doses ≥50 mg versus colchicine based on a negative binomial model (rate ratio: 0.28–0.38, p≤0.0083), and the percentage of patients experiencing ≥1 flare was significantly lower for all canakinumab doses (15% to 27%) versus colchicine (44%, p<0.05). There was a 64% to 72% reduction in the risk of experiencing ≥1 flare for canakinumab doses ≥50 mg versus colchicine at 16 weeks (hazard ratio (HR): 0.28–0.36, p≤0.05). The incidence of adverse events was similar across treatment groups. Conclusions Single canakinumab doses ≥50 mg or four 4-weekly doses provided superior prophylaxis against flares compared with daily colchicine 0.5 mg. PMID:21540198

Extended-Release Once-Daily Formulation of Tofacitinib: Evaluation of Pharmacokinetics Compared With Immediate-Release Tofacitinib and Impact of Food.

PubMed

Lamba, Manisha; Wang, Rong; Fletcher, Tracey; Alvey, Christine; Kushner, Joseph; Stock, Thomas C

2016-11-01

Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis. An extended-release (XR) formulation has been designed to provide a once-daily (QD) dosing option to patients to achieve comparable pharmacokinetic (PK) parameters to the twice-daily immediate-release (IR) formulation. We conducted 2 randomized, open-label, phase 1 studies in healthy volunteers. Study A characterized single-dose and steady-state PK of tofacitinib XR 11 mg QD and intended to demonstrate equivalence of exposure under single-dose and steady-state conditions to tofacitinib IR 5 mg twice daily. Study B assessed the effect of a high-fat meal on the bioavailability of tofacitinib from the XR formulation. Safety and tolerability were monitored in both studies. In study A (N = 24), the XR and IR formulations achieved time to maximum plasma concentration at 4 hours and 0.5 hours postdose, respectively; terminal half-life was 5.9 hours and 3.2 hours, respectively. Area under plasma concentration-time curve (AUC) and maximum plasma concentration (C max ) after single- and multiple-dose administration were equivalent between the XR and IR formulations. In study B (N = 24), no difference in AUC was observed for fed vs fasted conditions. C max increased by 27% under the fed state. On repeat administration, negligible accumulation (<20%) of systemic exposures was observed for both formulations. Steady state was achieved within 48 hours of dosing with the XR formulation. Tofacitinib administration as an XR or IR formulation was generally well tolerated in these studies. © 2016, The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals, Inc. on behalf of American College of Clinical Pharmacology.

Dioxin equivalency: Challenge to dose extrapolation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, J.F. Jr.; Silkworth, J.B.

1995-12-31

Extensive research has shown that all biological effects of dioxin-like agents are mediated via a single biochemical target, the Ah receptor (AhR), and that the relative biologic potencies of such agents in any given system, coupled with their exposure levels, may be described in terms of toxic equivalents (TEQ). It has also shown that the TEQ sources include not only chlorinated species such as the dioxins (PCDDs), PCDFs, and coplanar PCBs, but also non-chlorinated substances such as the PAHs of wood smoke, the AhR agonists of cooked meat, and the indolocarbazol (ICZ) derived from cruciferous vegetables. Humans have probably hadmore » elevated exposures to these non-chlorinated TEQ sources ever since the discoveries of fire, cooking, and the culinary use of Brassica spp. Recent assays of CYP1A2 induction show that these ``natural`` or ``traditional`` AhR agonists are contributing 50--100 times as much to average human TEQ exposures as do the chlorinated xenobiotics. Currently, the safe doses of the xenobiotic TEQ sources are estimated from their NOAELs and large extrapolation factors, derived from arbitrary mathematical models, whereas the NOAELs themselves are regarded as the safe doses for the TEQs of traditional dietary components. Available scientific data can neither support nor refute either approach to assessing the health risk of an individual chemical substance. However, if two substances be toxicologically equivalent, then their TEQ-adjusted health risks must also be equivalent, and the same dose extrapolation procedure should be used for both.« less

Method for the prediction of the effective dose equivalent to the crew of the International Space Station

NASA Astrophysics Data System (ADS)

El-Jaby, Samy; Tomi, Leena; Sihver, Lembit; Sato, Tatsuhiko; Richardson, Richard B.; Lewis, Brent J.

2014-03-01

This paper describes a methodology for assessing the pre-mission exposure of space crew aboard the International Space Station (ISS) in terms of an effective dose equivalent. In this approach, the PHITS Monte Carlo code was used to assess the particle transport of galactic cosmic radiation (GCR) and trapped radiation for solar maximum and minimum conditions through an aluminum shield thickness. From these predicted spectra, and using fluence-to-dose conversion factors, a scaling ratio of the effective dose equivalent rate to the ICRU ambient dose equivalent rate at a 10 mm depth was determined. Only contributions from secondary neutrons, protons, and alpha particles were considered in this analysis. Measurements made with a tissue equivalent proportional counter (TEPC) located at Service Module panel 327, as captured through a semi-empirical correlation in the ISSCREM code, where then scaled using this conversion factor for prediction of the effective dose equivalent. This analysis shows that at this location within the service module, the total effective dose equivalent is 10-30% less than the total TEPC dose equivalent. Approximately 75-85% of the effective dose equivalent is derived from the GCR. This methodology provides an opportunity for pre-flight predictions of the effective dose equivalent and therefore offers a means to assess the health risks of radiation exposure on ISS flight crew.

Bioequivalence of fixed-dose combination Myrin®-P Forte and reference drugs in loose combination.

PubMed

Wang, H F; Wang, R; O'Gorman, M; Crownover, P; Naqvi, A; Jafri, I

2013-12-01

Myrin®-P Forte is a fixed-dose combination (FDC) tablet containing rifampicin (RMP, 150 mg), isoniazid (INH, 75 mg), ethambutol (EMB) hydrochloride (275 mg) and pyrazinamide (PZA, 400 mg) developed for the treatment of tuberculosis (TB). This study was conducted at a single centre--the Pfizer Clinical Research Unit in Singapore. To demonstrate the bioequivalence of each drug component of the Myrin-P Forte FDC and the individual product in loose combination. In a randomized, open-label, single-dose, two-way, crossover study, subjects received single doses of Myrin-P Forte or four individual products under fasting conditions in a crossover fashion with at least 7 days washout between doses. The primary measures for comparison were peak plasma concentration (C(max)) and the area under plasma concentration-time curve (AUC). Of 36 subjects enrolled, 35 completed the study. The adjusted geometric mean ratios and 90% confidence intervals for C(max) and AUC values were completely contained within bioequivalence limits (80%, 125%) for all four drugs in both formulations. Both treatments were generally well tolerated in the study. The Myrin-P Forte FDC tablet formulation is bioequivalent to the four single-drug references for RMP, INH, EMB hydrochloride and PZA at equivalent doses.

Implementation of dual-energy technique for virtual monochromatic and linearly mixed CBCTs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Hao; Giles, William; Ren Lei

Purpose: To implement dual-energy imaging technique for virtual monochromatic (VM) and linearly mixed (LM) cone beam CTs (CBCTs) and to demonstrate their potential applications in metal artifact reduction and contrast enhancement in image-guided radiation therapy (IGRT). Methods: A bench-top CBCT system was used to acquire 80 kVp and 150 kVp projections, with an additional 0.8 mm tin filtration. To implement the VM technique, these projections were first decomposed into acrylic and aluminum basis material projections to synthesize VM projections, which were then used to reconstruct VM CBCTs. The effect of VM CBCT on the metal artifact reduction was evaluated withmore » an in-house titanium-BB phantom. The optimal VM energy to maximize contrast-to-noise ratio (CNR) for iodine contrast and minimize beam hardening in VM CBCT was determined using a water phantom containing two iodine concentrations. The LM technique was implemented by linearly combining the low-energy (80 kVp) and high-energy (150 kVp) CBCTs. The dose partitioning between low-energy and high-energy CBCTs was varied (20%, 40%, 60%, and 80% for low-energy) while keeping total dose approximately equal to single-energy CBCTs, measured using an ion chamber. Noise levels and CNRs for four tissue types were investigated for dual-energy LM CBCTs in comparison with single-energy CBCTs at 80, 100, 125, and 150 kVp. Results: The VM technique showed substantial reduction of metal artifacts at 100 keV with a 40% reduction in the background standard deviation compared to a 125 kVp single-energy scan of equal dose. The VM energy to maximize CNR for both iodine concentrations and minimize beam hardening in the metal-free object was 50 keV and 60 keV, respectively. The difference of average noise levels measured in the phantom background was 1.2% between dual-energy LM CBCTs and equivalent-dose single-energy CBCTs. CNR values in the LM CBCTs of any dose partitioning are better than those of 150 kVp single-energy CBCTs. The average CNR for four tissue types with 80% dose fraction at low-energy showed 9.0% and 4.1% improvement relative to 100 kVp and 125 kVp single-energy CBCTs, respectively. CNRs for low-contrast objects improved as dose partitioning was more heavily weighted toward low-energy (80 kVp) for LM CBCTs. Conclusions: Dual-energy CBCT imaging techniques were implemented to synthesize VM CBCT and LM CBCTs. VM CBCT was effective at achieving metal artifact reduction. Depending on the dose-partitioning scheme, LM CBCT demonstrated the potential to improve CNR for low contrast objects compared to single-energy CBCT acquired with equivalent dose.« less

10 CFR 60.136 - Preclosure controlled area.

Code of Federal Regulations, 2010 CFR

2010-01-01

... limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The eye dose equivalent shall not exceed 0.15 Sv (15 rem), and the shallow dose...

10 CFR 60.136 - Preclosure controlled area.

Code of Federal Regulations, 2011 CFR

2011-01-01

... limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The eye dose equivalent shall not exceed 0.15 Sv (15 rem), and the shallow dose...

10 CFR 60.136 - Preclosure controlled area.

Code of Federal Regulations, 2013 CFR

2013-01-01

... limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The eye dose equivalent shall not exceed 0.15 Sv (15 rem), and the shallow dose...

10 CFR 60.136 - Preclosure controlled area.

Code of Federal Regulations, 2012 CFR

2012-01-01

... limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The eye dose equivalent shall not exceed 0.15 Sv (15 rem), and the shallow dose...

10 CFR 60.136 - Preclosure controlled area.

Code of Federal Regulations, 2014 CFR

2014-01-01

... limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The eye dose equivalent shall not exceed 0.15 Sv (15 rem), and the shallow dose...

Can the Equivalent Sphere Model Approximate Organ Doses in Space Radiation Environments?

NASA Technical Reports Server (NTRS)

Zi-Wei, Lin

2007-01-01

In space radiation calculations it is often useful to calculate the dose or dose equivalent in blood-forming organs (BFO). the skin or the eye. It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However previous studies have shown that a 5cm sphere gives conservative dose values for BFO. In this study we use a deterministic radiation transport with the Computerized Anatomical Man model to investigate whether the equivalent sphere model can approximate organ doses in space radiation environments. We find that for galactic cosmic rays environments the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent and marginally well for the BFO dose and the dose equivalent of the eye or the skin. For solar particle events the radius parameters for the organ dose equivalent increase with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin The ranges of the radius parameters are also shown and the BFO radius parameters are found to be significantly larger than 5 cm in all eases.

Single-Dose Primaquine in a Preclinical Model of Glucose-6-Phosphate Dehydrogenase Deficiency: Implications for Use in Malaria Transmission-Blocking Programs

PubMed Central

Wickham, Kristina S.; Baresel, Paul C.; Sousa, Jason; Vuong, Chau T.; Reichard, Gregory A.; Campo, Brice; Tekwani, Babu L.; Walker, Larry A.

2016-01-01

Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency (G6PDd) are at risk for developing hemolytic anemia when given the antimalarial drug primaquine (PQ). The WHO Evidence Review Group released a report suggesting that mass administration of a single dose of PQ at 0.25 mg of base/kg of body weight (mpk) (mouse equivalent of 3.125 mpk) could potentially reduce malaria transmission based on its gametocytocidal activity and could be safely administered to G6PD-deficient individuals, but there are limited safety data available confirming the optimum single dose of PQ. A single-dose administration of PQ was therefore assessed in our huRBC-SCID mouse model used to predict hemolytic toxicity with respect to G6PD deficiency. In this model, nonobese diabetic (NOD)/SCID mice are engrafted with human red blood cells (huRBC) from donors with the African or Mediterranean variant of G6PDd (A-G6PDd or Med-G6PDd, respectively) and demonstrate dose-dependent sensitivity to PQ. In mice engrafted with A-G6PD-deficient huRBC, single-dose PQ at 3.125, 6.25, or 12.5 mpk had no significant loss of huRBC compared to the vehicle control group. In contrast, in mice engrafted with Med-G6PDd huRBC, a single dose of PQ at 3.125, 6.25, or 12.5 mpk resulted in a significant, dose-dependent loss of huRBC compared to the value for the vehicle control group. Our data suggest that administration of a single low dose of 0.25 mpk of PQ could induce hemolytic anemia in Med-G6PDd individuals but that use of single-dose PQ at 0.25 mpk as a gametocytocidal drug to block transmission would be safe in areas where A-G6PDd predominates. PMID:27458212

Single-Dose Primaquine in a Preclinical Model of Glucose-6-Phosphate Dehydrogenase Deficiency: Implications for Use in Malaria Transmission-Blocking Programs.

PubMed

Wickham, Kristina S; Baresel, Paul C; Marcsisin, Sean R; Sousa, Jason; Vuong, Chau T; Reichard, Gregory A; Campo, Brice; Tekwani, Babu L; Walker, Larry A; Rochford, Rosemary

2016-10-01

Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency (G6PDd) are at risk for developing hemolytic anemia when given the antimalarial drug primaquine (PQ). The WHO Evidence Review Group released a report suggesting that mass administration of a single dose of PQ at 0.25 mg of base/kg of body weight (mpk) (mouse equivalent of 3.125 mpk) could potentially reduce malaria transmission based on its gametocytocidal activity and could be safely administered to G6PD-deficient individuals, but there are limited safety data available confirming the optimum single dose of PQ. A single-dose administration of PQ was therefore assessed in our huRBC-SCID mouse model used to predict hemolytic toxicity with respect to G6PD deficiency. In this model, nonobese diabetic (NOD)/SCID mice are engrafted with human red blood cells (huRBC) from donors with the African or Mediterranean variant of G6PDd (A-G6PDd or Med-G6PDd, respectively) and demonstrate dose-dependent sensitivity to PQ. In mice engrafted with A-G6PD-deficient huRBC, single-dose PQ at 3.125, 6.25, or 12.5 mpk had no significant loss of huRBC compared to the vehicle control group. In contrast, in mice engrafted with Med-G6PDd huRBC, a single dose of PQ at 3.125, 6.25, or 12.5 mpk resulted in a significant, dose-dependent loss of huRBC compared to the value for the vehicle control group. Our data suggest that administration of a single low dose of 0.25 mpk of PQ could induce hemolytic anemia in Med-G6PDd individuals but that use of single-dose PQ at 0.25 mpk as a gametocytocidal drug to block transmission would be safe in areas where A-G6PDd predominates. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

A new single crystal diamond dosimeter for small beam: comparison with different commercial active detectors.

PubMed

Marsolat, F; Tromson, D; Tranchant, N; Pomorski, M; Le Roy, M; Donois, M; Moignau, F; Ostrowsky, A; De Carlan, L; Bassinet, C; Huet, C; Derreumaux, S; Chea, M; Cristina, K; Boisserie, G; Bergonzo, P

2013-11-07

Recent developments of new therapy techniques using small photon beams, such as stereotactic radiotherapy, require suitable detectors to determine the delivered dose with a high accuracy. The dosimeter has to be as close as possible to tissue equivalence and to exhibit a small detection volume compared to the size of the irradiation field, because of the lack of lateral electronic equilibrium in small beam. Characteristics of single crystal diamond (tissue equivalent material Z = 6, high density) make it an ideal candidate to fulfil most of small beam dosimetry requirements. A commercially available Element Six electronic grade synthetic diamond was used to develop a single crystal diamond dosimeter (SCDDo) with a small detection volume (0.165 mm(3)). Long term stability was studied by irradiating the SCDDo in a (60)Co beam over 14 h. A good stability (deviation less than ± 0.1%) was observed. Repeatability, dose linearity, dose rate dependence and energy dependence were studied in a 10 × 10 cm(2) beam produced by a Varian Clinac 2100 C linear accelerator. SCDDo lateral dose profile, depth dose curve and output factor (OF) measurements were performed for small photon beams with a micro multileaf collimator m3 (BrainLab) attached to the linac. This study is focused on the comparison of SCDDo measurements to those obtained with different commercially available active detectors: an unshielded silicon diode (PTW 60017), a shielded silicon diode (Sun Nuclear EDGE), a PinPoint ionization chamber (PTW 31014) and two natural diamond detectors (PTW 60003). SCDDo presents an excellent spatial resolution for dose profile measurements, due to its small detection volume. Low energy dependence (variation of 1.2% between 6 and 18 MV photon beam) and low dose rate dependence of the SCDDo (variation of 1% between 0.53 and 2.64 Gy min(-1)) are obtained, explaining the good agreement between the SCDDo and the efficient unshielded diode (PTW 60017) in depth dose curve measurements. For field sizes ranging from 0.6 × 0.6 to 10 × 10 cm(2), OFs obtained with the SCDDo are between the OFs measured with the PinPoint ionization chamber and the Sun Nuclear EDGE diode that are known to respectively underestimate and overestimate OF values in small beam, due to the large detection volume of the chamber and the non-water equivalence of both detectors.

Comparison of the Efficacy and Safety of 2 Acetaminophen Dosing Regimens in Febrile Infants and Children: A Report on 3 Legacy Studies.

PubMed

Temple, Anthony R; Zimmerman, Brenda; Gelotte, Cathy; Kuffner, Edwin K

2017-01-01

Compare efficacy and safety of 10 to 15 mg/kg with 20 to 30 mg/kg acetaminophen in febrile children 6 months to ≤ 11 years from 3 double-blind, randomized, single or multiple dose studies. Doses were compared on sum of the temperature differences (SUMDIFF), maximum temperature difference (MAXDIFF), temperature differences at each time point, and dose by time interactions. Alanine aminotransferase (ALT) was evaluated in the 72-hour duration study. A single dose of acetaminophen 20 to 30 mg/kg produced a greater effect on temperature decrement and duration of antipyretic effect over 8 hours than a single dose of 10 to 15 mg/kg. When equivalent total doses (i.e., 2 doses of 10 to 15 mg/kg given at 4-hour intervals and 1 dose of 20 to 30 mg/kg) were given over the initial 8-hour period, there were no significant temperature differences. Over a 72-hour period, 10 to 15 mg/kg acetaminophen administered every 4 hours maintained a more consistent temperature decrement than 20 to 30 mg/kg acetaminophen administered every 8 hours. Following doses of 60 to 90 mg/kg/day for up to 72 hours, no child had a clinically important increase in ALT from baseline. The number of children with reported adverse events was similar between doses. Data demonstrate the antipyretic effect of acetaminophen is dependent on total dose over a given time interval. These 3 studies provide clinical evidence that the recommended standard acetaminophen dose of 10 to 15 mg/kg is a safe and effective dose for treating fever in pediatric patients when administered as a single dose or as multiple doses for up to 72 hours.

Neutron dose equivalent meter

DOEpatents

Olsher, Richard H.; Hsu, Hsiao-Hua; Casson, William H.; Vasilik, Dennis G.; Kleck, Jeffrey H.; Beverding, Anthony

1996-01-01

A neutron dose equivalent detector for measuring neutron dose capable of accurately responding to neutron energies according to published fluence to dose curves. The neutron dose equivalent meter has an inner sphere of polyethylene, with a middle shell overlying the inner sphere, the middle shell comprising RTV.RTM. silicone (organosiloxane) loaded with boron. An outer shell overlies the middle shell and comprises polyethylene loaded with tungsten. The neutron dose equivalent meter defines a channel through the outer shell, the middle shell, and the inner sphere for accepting a neutron counter tube. The outer shell is loaded with tungsten to provide neutron generation, increasing the neutron dose equivalent meter's response sensitivity above 8 MeV.

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2010 CFR

2010-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2011 CFR

2011-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2014 CFR

2014-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2013 CFR

2013-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

10 CFR 835.702 - Individual monitoring records.

Code of Federal Regulations, 2012 CFR

2012-01-01

... emergency exposures. (b) Recording of the non-uniform equivalent dose to the skin is not required if the... internal dose (committed effective dose or committed equivalent dose) is not required for any monitoring...: (i) The effective dose from external sources of radiation (equivalent dose to the whole body may be...

Radiation tolerance of readout electronics for Belle II

NASA Astrophysics Data System (ADS)

Higuchi, T.; Nakao, M.; Nakano, E.

2012-02-01

We plan to start the Belle II experiment in 2015 and to continue data taking for more than ten years. Because some of the front-end electronics cards of Belle II are located inside the detector, radiation effects onto their components will be a severe problem. Using experimental exposure facilities of neutrons and γ rays, we study the radiation effects from these particles to the Virtex-5 FPGA, optical transceivers, and voltage regulators. The Virtex-5 FPGA is found to keep its operation after irradiation of more than 20-year-equivalent neutron flux of Belle II and 88-year-equivalent γ-ray dose. We observe single event upsets (SEUs) and multiple bit upsets (MBUs) in the Virtex-5 FPGA in the neutron irradiation. We also find almost doubled SEU counts in the Virtex-5 FPGA bombarded from its tail side than its head side. We extrapolate the observed SEU and MBU counts in the Virtex-5 FPGA to the entire readout system of the Belle II central drift chamber, and expect the SEU and MBU rates as one SEU per four minutes and one MBU per 11.5 hours, respectively. The optical transceivers are found to keep its operation after integration of 12-year-equivalent neutron flux, while they are killed by about 3-year-equivalent γ-ray dose, which should be solved in the future research. The voltage regulators are found to keep its operation for more than 10-year-equivalent γ-ray dose.

Can we use the equivalent sphere model to approximate organ doses in space radiation environments?

NASA Astrophysics Data System (ADS)

Lin, Zi-Wei

For space radiation protection one often calculates the dose or dose equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to approximate the BFO dose. However, previous studies have concluded that a 5cm sphere gives a very different dose from the exact BFO dose. One study concludes that a 9cm sphere is a reasonable approximation for the BFO dose in solar particle event (SPE) environments. In this study we investigate the reason behind these observations and extend earlier studies by studying whether BFO, eyes or the skin can be approximated by the equivalent sphere model in different space radiation environments such as solar particle events and galactic cosmic ray (GCR) environments. We take the thickness distribution functions of the organs from the CAM (Computerized Anatomical Man) model, then use a deterministic radiation transport to calculate organ doses in different space radiation environments. The organ doses have been evaluated with a water or aluminum shielding from 0 to 20 g/cm2. We then compare these exact doses with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we propose to use a modified equivalent sphere model with two radius parameters to represent the skin or eyes. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for eyes or the skin. For galactic cosmic rays environments, the equivalent sphere model with one organ-specific radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of eyes or the skin, but is unacceptable for the dose of eyes or the skin. The BFO radius parameters are found to be significantly larger than 5 cm in all cases, consistent with the conclusion of an earlier study. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and 11 cm for the BFO, 3.7 to 4.8 cm for eyes, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose. In the proposed modified equivalent sphere model, the range of each of the two radius parameters for the skin (or eyes) is much tighter than that in the equivalent sphere model with one radius parameter. Our results thus show that the equivalent sphere model works better in galactic cosmic rays environments than in solar particle events. The model works well or marginally well for BFO but usually does not work for eyes or the skin. A modified model with two radius parameters works much better in approximating the dose and dose equivalent in eyes or the skin.

Volumetric-modulated arc therapy for the treatment of a large planning target volume in thoracic esophageal cancer.

PubMed

Abbas, Ahmar S; Moseley, Douglas; Kassam, Zahra; Kim, Sun Mo; Cho, Charles

2013-05-06

Recently, volumetric-modulated arc therapy (VMAT) has demonstrated the ability to deliver radiation dose precisely and accurately with a shorter delivery time compared to conventional intensity-modulated fixed-field treatment (IMRT). We applied the hypothesis of VMAT technique for the treatment of thoracic esophageal carcinoma to determine superior or equivalent conformal dose coverage for a large thoracic esophageal planning target volume (PTV) with superior or equivalent sparing of organs-at-risk (OARs) doses, and reduce delivery time and monitor units (MUs), in comparison with conventional fixed-field IMRT plans. We also analyzed and compared some other important metrics of treatment planning and treatment delivery for both IMRT and VMAT techniques. These metrics include: 1) the integral dose and the volume receiving intermediate dose levels between IMRT and VMATI plans; 2) the use of 4D CT to determine the internal motion margin; and 3) evaluating the dosimetry of every plan through patient-specific QA. These factors may impact the overall treatment plan quality and outcomes from the individual planning technique used. In this study, we also examined the significance of using two arcs vs. a single-arc VMAT technique for PTV coverage, OARs doses, monitor units and delivery time. Thirteen patients, stage T2-T3 N0-N1 (TNM AJCC 7th edn.), PTV volume median 395 cc (range 281-601 cc), median age 69 years (range 53 to 85), were treated from July 2010 to June 2011 with a four-field (n = 4) or five-field (n = 9) step-and-shoot IMRT technique using a 6 MV beam to a prescribed dose of 50 Gy in 20 to 25 F. These patients were retrospectively replanned using single arc (VMATI, 91 control points) and two arcs (VMATII, 182 control points). All treatment plans of the 13 study cases were evaluated using various dose-volume metrics. These included PTV D99, PTV D95, PTV V9547.5Gy(95%), PTV mean dose, Dmax, PTV dose conformity (Van't Riet conformation number (CN)), mean lung dose, lung V20 and V5, liver V30, and Dmax to the spinal canal prv3mm. Also examined were the total plan monitor units (MUs) and the beam delivery time. Equivalent target coverage was observed with both VMAT single and two-arc plans. The comparison of VMATI with fixed-field IMRT demonstrated equivalent target coverage; statistically no significant difference were found in PTV D99 (p = 0.47), PTV mean (p = 0.12), PTV D95 and PTV V9547.5Gy (95%) (p = 0.38). However, Dmax in VMATI plans was significantly lower compared to IMRT (p = 0.02). The Van't Riet dose conformation number (CN) was also statistically in favor of VMATI plans (p = 0.04). VMATI achieved lower lung V20 (p = 0.05), whereas lung V5 (p = 0.35) and mean lung dose (p = 0.62) were not significantly different. The other OARs, including spinal canal, liver, heart, and kidneys showed no statistically significant differences between the two techniques. Treatment time delivery for VMATI plans was reduced by up to 55% (p = 5.8E-10) and MUs reduced by up to 16% (p = 0.001). Integral dose was not statistically different between the two planning techniques (p = 0.99). There were no statistically significant differences found in dose distribution of the two VMAT techniques (VMATI vs. VMATII) Dose statistics for both VMAT techniques were: PTV D99 (p = 0.76), PTV D95 (p = 0.95), mean PTV dose (p = 0.78), conformation number (CN) (p = 0.26), and MUs (p = 0.1). However, the treatment delivery time for VMATII increased significantly by two-fold (p = 3.0E-11) compared to VMATI. VMAT-based treatment planning is safe and deliverable for patients with thoracic esophageal cancer with similar planning goals, when compared to standard IMRT. The key benefit for VMATI was the reduction in treatment delivery time and MUs, and improvement in dose conformality. In our study, we found no significant difference in VMATII over single-arc VMATI for PTV coverage or OARs doses. However, we observed significant increase in delivery time for VMATII compared to VMATI.

42 CFR 81.4 - Definition of terms used in this part.

Code of Federal Regulations, 2011 CFR

2011-10-01

...]. (e) Equivalent dose means the absorbed dose in a tissue or organ multiplied by a radiation weighting... dose means the portion of the equivalent dose that is received from radiation sources outside of the... pattern and level of radiation exposure. (h) Internal dose means the portion of the equivalent dose that...

Antipsychotic dose equivalents and dose-years: a standardized method for comparing exposure to different drugs.

PubMed

Andreasen, Nancy C; Pressler, Marcus; Nopoulos, Peg; Miller, Del; Ho, Beng-Choon

2010-02-01

A standardized quantitative method for comparing dosages of different drugs is a useful tool for designing clinical trials and for examining the effects of long-term medication side effects such as tardive dyskinesia. Such a method requires establishing dose equivalents. An expert consensus group has published charts of equivalent doses for various antipsychotic medications for first- and second-generation medications. These charts were used in this study. Regression was used to compare each drug in the experts' charts to chlorpromazine and haloperidol and to create formulas for each relationship. The formulas were solved for chlorpromazine 100 mg and haloperidol 2 mg to derive new chlorpromazine and haloperidol equivalents. The formulas were incorporated into our definition of dose-years such that 100 mg/day of chlorpromazine equivalent or 2 mg/day of haloperidol equivalent taken for 1 year is equal to one dose-year. All comparisons to chlorpromazine and haloperidol were highly linear with R(2) values greater than .9. A power transformation further improved linearity. By deriving a unique formula that converts doses to chlorpromazine or haloperidol equivalents, we can compare otherwise dissimilar drugs. These equivalents can be multiplied by the time an individual has been on a given dose to derive a cumulative value measured in dose-years in the form of (chlorpromazine equivalent in mg) x (time on dose measured in years). After each dose has been converted to dose-years, the results can be summed to provide a cumulative quantitative measure of lifetime exposure. Copyright 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Can the Equivalent Sphere Model Approximate Organ Doses in Space?

NASA Technical Reports Server (NTRS)

Lin, Zi-Wei

2007-01-01

For space radiation protection it is often useful to calculate dose or dose,equivalent in blood forming organs (BFO). It has been customary to use a 5cm equivalent sphere to. simulate the BFO dose. However, many previous studies have concluded that a 5cm sphere gives very different dose values from the exact BFO values. One study [1] . concludes that a 9 cm sphere is a reasonable approximation for BFO'doses in solar particle event environments. In this study we use a deterministic radiation transport [2] to investigate the reason behind these observations and to extend earlier studies. We take different space radiation environments, including seven galactic cosmic ray environments and six large solar particle events, and calculate the dose and dose equivalent in the skin, eyes and BFO using their thickness distribution functions from the CAM (Computerized Anatomical Man) model [3] The organ doses have been evaluated with a water or aluminum shielding of an areal density from 0 to 20 g/sq cm. We then compare with results from the equivalent sphere model and determine in which cases and at what radius parameters the equivalent sphere model is a reasonable approximation. Furthermore, we address why the equivalent sphere model is not a good approximation in some cases. For solar particle events, we find that the radius parameters for the organ dose equivalent increase significantly with the shielding thickness, and the model works marginally for BFO but is unacceptable for the eye or the skin. For galactic cosmic rays environments, the equivalent sphere model with an organ-specific constant radius parameter works well for the BFO dose equivalent, marginally well for the BFO dose and the dose equivalent of the eye or the skin, but is unacceptable for the dose of the eye or the skin. The ranges of the radius parameters are also being investigated, and the BFO radius parameters are found to be significantly, larger than 5 cm in all cases, consistent with the conclusion of an earlier study [I]. The radius parameters for the dose equivalent in GCR environments are approximately between 10 and I I cm for the BFO, 3.7 to 4.8 cm for the eye, and 3.5 to 5.6 cm for the skin; while the radius parameters are between 10 and 13 cm for the BFO dose.

Implementation of an Analytical Model for Leakage Neutron Equivalent Dose in a Proton Radiotherapy Planning System

PubMed Central

Eley, John; Newhauser, Wayne; Homann, Kenneth; Howell, Rebecca; Schneider, Christopher; Durante, Marco; Bert, Christoph

2015-01-01

Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects. PMID:25768061

Implementation of an analytical model for leakage neutron equivalent dose in a proton radiotherapy planning system.

PubMed

Eley, John; Newhauser, Wayne; Homann, Kenneth; Howell, Rebecca; Schneider, Christopher; Durante, Marco; Bert, Christoph

2015-03-11

Equivalent dose from neutrons produced during proton radiotherapy increases the predicted risk of radiogenic late effects. However, out-of-field neutron dose is not taken into account by commercial proton radiotherapy treatment planning systems. The purpose of this study was to demonstrate the feasibility of implementing an analytical model to calculate leakage neutron equivalent dose in a treatment planning system. Passive scattering proton treatment plans were created for a water phantom and for a patient. For both the phantom and patient, the neutron equivalent doses were small but non-negligible and extended far beyond the therapeutic field. The time required for neutron equivalent dose calculation was 1.6 times longer than that required for proton dose calculation, with a total calculation time of less than 1 h on one processor for both treatment plans. Our results demonstrate that it is feasible to predict neutron equivalent dose distributions using an analytical dose algorithm for individual patients with irregular surfaces and internal tissue heterogeneities. Eventually, personalized estimates of neutron equivalent dose to organs far from the treatment field may guide clinicians to create treatment plans that reduce the risk of late effects.

Dose Equivalents for Antipsychotic Drugs: The DDD Method.

PubMed

Leucht, Stefan; Samara, Myrto; Heres, Stephan; Davis, John M

2016-07-01

Dose equivalents of antipsychotics are an important but difficult to define concept, because all methods have weaknesses and strongholds. We calculated dose equivalents based on defined daily doses (DDDs) presented by the World Health Organisation's Collaborative Center for Drug Statistics Methodology. Doses equivalent to 1mg olanzapine, 1mg risperidone, 1mg haloperidol, and 100mg chlorpromazine were presented and compared with the results of 3 other methods to define dose equivalence (the "minimum effective dose method," the "classical mean dose method," and an international consensus statement). We presented dose equivalents for 57 first-generation and second-generation antipsychotic drugs, available as oral, parenteral, or depot formulations. Overall, the identified equivalent doses were comparable with those of the other methods, but there were also outliers. The major strength of this method to define dose response is that DDDs are available for most drugs, including old antipsychotics, that they are based on a variety of sources, and that DDDs are an internationally accepted measure. The major limitations are that the information used to estimate DDDS is likely to differ between the drugs. Moreover, this information is not publicly available, so that it cannot be reviewed. The WHO stresses that DDDs are mainly a standardized measure of drug consumption, and their use as a measure of dose equivalence can therefore be misleading. We, therefore, recommend that if alternative, more "scientific" dose equivalence methods are available for a drug they should be preferred to DDDs. Moreover, our summary can be a useful resource for pharmacovigilance studies. © The Author 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Moving toward focal therapy in prostate cancer: dual-isotope permanent seed implants as a possible solution.

PubMed

Todor, Dorin A; Barani, Igor J; Lin, Peck-Sun; Anscher, Mitchell S

2011-09-01

To compare the ability of single- and dual-isotope prostate seed implants to escalate biologically effective dose (BED) to foci of disease while reducing prescription dose to the prostate. Nine plans, using 125I, 103Pd, and 131Cs alone and in combination were created retrospectively for 2 patients. Ultrasound and MRI/MRS datasets were used for treatment planning. Voxel-by-voxel BED was calculated for single- and dual-isotope plans. Equivalent uniform BED (EUBED) was used to compare plans. The MRS-positive planning target volumes (PTVi) were delineated along with PTV (prostate+5 mm), rectum, and urethra. Single-isotope implants, prescribed to conventional doses, were generated to achieve good PTV coverage. The PTVi were prospectively used to generate implants using mixtures of isotopes. For mixed-radioisotope implants, we also explored the impact on EUBED of lowering prescription doses by 15%. The EUBED of PTVi in the setting of primary 125I implant increased 20-66% when 103Pd and 131Cs were used compared with 125I boost. Decreasing prescription dose by 15% in mixed-isotope implants results in a potential 10% reduction in urethral EUBED with preservation of PTV coverage while still boosting PTVi (up to 80%). When radiobiologic parameters corresponding to more-aggressive disease are assigned to foci, faster-decaying isotopes used in mixed implants have the potential to preserve the equivalent biological effect of mono-isotope implants considering less-aggressive disease distributed in the entire prostate. This is a hypothesis-generating study proposing a treatment paradigm that could be the middle ground between whole-gland irradiation and focal-only treatment. The use of two isotopes concurrent with decreasing the minimal peripheral dose is shown to increase EUBED of selected subvolumes while preserving the therapeutic effect at the level of the gland. Copyright © 2011 Elsevier Inc. All rights reserved.

Moving Toward Focal Therapy in Prostate Cancer: Dual-Isotope Permanent Seed Implants as a Possible Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Todor, Dorin A., E-mail: dtodor@mcvh-vcu.edu; Barani, Igor J.; Lin, Peck-Sun

2011-09-01

Purpose: To compare the ability of single- and dual-isotope prostate seed implants to escalate biologically effective dose (BED) to foci of disease while reducing prescription dose to the prostate. Methods and Materials: Nine plans, using {sup 125}I, {sup 103}Pd, and {sup 131}Cs alone and in combination were created retrospectively for 2 patients. Ultrasound and MRI/MRS datasets were used for treatment planning. Voxel-by-voxel BED was calculated for single- and dual-isotope plans. Equivalent uniform BED (EUBED) was used to compare plans. The MRS-positive planning target volumes (PTV{sub i}) were delineated along with PTV (prostate + 5 mm), rectum, and urethra. Single-isotope implants,more » prescribed to conventional doses, were generated to achieve good PTV coverage. The PTV{sub i} were prospectively used to generate implants using mixtures of isotopes. For mixed-radioisotope implants, we also explored the impact on EUBED of lowering prescription doses by 15%. Results: The EUBED of PTV{sub i} in the setting of primary {sup 125}I implant increased 20-66% when {sup 103}Pd and {sup 131}Cs were used compared with {sup 125}I boost. Decreasing prescription dose by 15% in mixed-isotope implants results in a potential 10% reduction in urethral EUBED with preservation of PTV coverage while still boosting PTV{sub i} (up to 80%). When radiobiologic parameters corresponding to more-aggressive disease are assigned to foci, faster-decaying isotopes used in mixed implants have the potential to preserve the equivalent biological effect of mono-isotope implants considering less-aggressive disease distributed in the entire prostate. Conclusions: This is a hypothesis-generating study proposing a treatment paradigm that could be the middle ground between whole-gland irradiation and focal-only treatment. The use of two isotopes concurrent with decreasing the minimal peripheral dose is shown to increase EUBED of selected subvolumes while preserving the therapeutic effect at the level of the gland.« less

Radiation exposure from consumer products and miscellaneous sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1977-01-01

This review of the literature indicates that there is a variety of consumer products and miscellaneous sources of radiation that result in exposure to the U.S. population. A summary of the number of people exposed to each such source, an estimate of the resulting dose equivalents to the exposed population, and an estimate of the average annual population dose equivalent are tabulated. A review of the data in this table shows that the total average annual contribution to the whole-body dose equivalent of the U.S. population from consumer products is less than 5 mrem; about 70 percent of this arisesmore » from the presence of naturally-occurring radionuclides in building materials. Some of the consumer product sources contribute exposure mainly to localized tissues or organs. Such localized estimates include: 0.5 to 1 mrem to the average annual population lung dose equivalent (generalized); 2 rem to the average annual population bronchial epithelial dose equivalent (localized); and 10 to 15 rem to the average annual population basal mucosal dose equivalent (basal mucosa of the gum). Based on these estimates, these sources may be grouped or classified as those that involve many people and the dose equivalent is relative large or those that involve many people but the dose equivalent is relatively small, or the dose equivalent is relatively large but the number of people involved is small.« less

Variation of indoor radon concentration and ambient dose equivalent rate in different outdoor and indoor environments.

PubMed

Stojanovska, Zdenka; Boev, Blazo; Zunic, Zora S; Ivanova, Kremena; Ristova, Mimoza; Tsenova, Martina; Ajka, Sorsa; Janevik, Emilija; Taleski, Vaso; Bossew, Peter

2016-05-01

Subject of this study is an investigation of the variations of indoor radon concentration and ambient dose equivalent rate in outdoor and indoor environments of 40 dwellings, 31 elementary schools and five kindergartens. The buildings are located in three municipalities of two, geologically different, areas of the Republic of Macedonia. Indoor radon concentrations were measured by nuclear track detectors, deployed in the most occupied room of the building, between June 2013 and May 2014. During the deploying campaign, indoor and outdoor ambient dose equivalent rates were measured simultaneously at the same location. It appeared that the measured values varied from 22 to 990 Bq/m(3) for indoor radon concentrations, from 50 to 195 nSv/h for outdoor ambient dose equivalent rates, and from 38 to 184 nSv/h for indoor ambient dose equivalent rates. The geometric mean value of indoor to outdoor ambient dose equivalent rates was found to be 0.88, i.e. the outdoor ambient dose equivalent rates were on average higher than the indoor ambient dose equivalent rates. All measured can reasonably well be described by log-normal distributions. A detailed statistical analysis of factors which influence the measured quantities is reported.

10 CFR 20.1208 - Dose equivalent to an embryo/fetus.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 1 2013-01-01 2013-01-01 false Dose equivalent to an embryo/fetus. 20.1208 Section 20.1208 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose...

10 CFR 20.1208 - Dose equivalent to an embryo/fetus.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Dose equivalent to an embryo/fetus. 20.1208 Section 20.1208 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose...

10 CFR 20.1208 - Dose equivalent to an embryo/fetus.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 1 2014-01-01 2014-01-01 false Dose equivalent to an embryo/fetus. 20.1208 Section 20.1208 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose...

10 CFR 20.1208 - Dose equivalent to an embryo/fetus.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 1 2012-01-01 2012-01-01 false Dose equivalent to an embryo/fetus. 20.1208 Section 20.1208 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose...

10 CFR 20.1208 - Dose equivalent to an embryo/fetus.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false Dose equivalent to an embryo/fetus. 20.1208 Section 20.1208 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose...

Dose Enhancement near Metal Interfaces in Synthetic Diamond Based X-ray Dosimeters

NASA Astrophysics Data System (ADS)

Alamoudi, Dalal

Diamond is an attractive material for medical dosimetry due to its radiation hardness, fast response, chemical resilience, small sensitive volume, high spatial resolution, near-tissue equivalence, and energy and dose rate independence. These properties make diamond a promising material for medical dosimetry compared to other semiconductor detector materials and wider radiation detection applications. This study is focused on one of the important factors to consider in the radiation detector; the influence of dose enhancement on the photocurrent performance at metallic interfaces in synthetic diamond radiation dosimeters with carbon based electrodes as a function of bias voltages. Monte Carlo (MC) simulations with BEAMnrc code were carried out to simulate the dose enhancement factor (DEF) and compared against the equivalent photocurrent ratio from experimental investigation. MC simulations show that the sensitive region for the absorbed dose distribution covers a few micrometers distances from the interface. Experimentally, two single crystal (SC) and one polycrystalline (PC) samples with carbon based electrodes were used. The samples were each mounted inside a tissue equivalent encapsulation design in order to minimize fluence perturbations. Copper, Gold and Lead have been investigated experimentally as generators of photoelectrons using 50 kVp and 100 kVp X-rays relevant for medical dosimetry. The results show enhancement in the detectors' photocurrent performance when different metals are butted up to the diamond detector. The variation in the photocurrent ratio measurements depends on the type of diamond samples, their electrode fabrication and the applied bias voltages indicating that the dose enhancement from diamond-metal interface modifies the electronic performance of the detector.

Assessment of organ-specific neutron equivalent doses in proton therapy using computational whole-body age-dependent voxel phantoms

NASA Astrophysics Data System (ADS)

Zacharatou Jarlskog, Christina; Lee, Choonik; Bolch, Wesley E.; Xu, X. George; Paganetti, Harald

2008-02-01

Proton beams used for radiotherapy will produce neutrons when interacting with matter. The purpose of this study was to quantify the equivalent dose to tissue due to secondary neutrons in pediatric and adult patients treated by proton therapy for brain lesions. Assessment of the equivalent dose to organs away from the target requires whole-body geometrical information. Furthermore, because the patient geometry depends on age at exposure, age-dependent representations are also needed. We implemented age-dependent phantoms into our proton Monte Carlo dose calculation environment. We considered eight typical radiation fields, two of which had been previously used to treat pediatric patients. The other six fields were additionally considered to allow a systematic study of equivalent doses as a function of field parameters. For all phantoms and all fields, we simulated organ-specific equivalent neutron doses and analyzed for each organ (1) the equivalent dose due to neutrons as a function of distance to the target; (2) the equivalent dose due to neutrons as a function of patient age; (3) the equivalent dose due to neutrons as a function of field parameters; and (4) the ratio of contributions to secondary dose from the treatment head versus the contribution from the patient's body tissues. This work reports organ-specific equivalent neutron doses for up to 48 organs in a patient. We demonstrate quantitatively how organ equivalent doses for adult and pediatric patients vary as a function of patient's age, organ and field parameters. Neutron doses increase with increasing range and modulation width but decrease with field size (as defined by the aperture). We analyzed the ratio of neutron dose contributions from the patient and from the treatment head, and found that neutron-equivalent doses fall off rapidly as a function of distance from the target, in agreement with experimental data. It appears that for the fields used in this study, the neutron dose lateral to the field is smaller than the reported scattered photon doses in a typical intensity-modulated photon treatment. Most importantly, our study shows that neutron doses to specific organs depend considerably on the patient's age and body stature. The younger the patient, the higher the dose deposited due to neutrons. Given the fact that the risk also increases with decreasing patient age, this factor needs to be taken into account when treating pediatric patients of very young ages and/or of small body size. The neutron dose from a course of proton therapy treatment (assuming 70 Gy in 30 fractions) could potentially (depending on patient's age, organ, treatment site and area of CT scan) be equivalent to up to ~30 CT scans.

Derivation of mean dose tolerances for new fractionation schemes and treatment modalities

NASA Astrophysics Data System (ADS)

Perkó, Zoltán; Bortfeld, Thomas; Hong, Theodore; Wolfgang, John; Unkelbach, Jan

2018-02-01

Avoiding toxicities in radiotherapy requires the knowledge of tolerable organ doses. For new, experimental fractionation schemes (e.g. hypofractionation) these are typically derived from traditional schedules using the biologically effective dose (BED) model. In this report we investigate the difficulties of establishing mean dose tolerances that arise since the mean BED depends on the entire spatial dose distribution, rather than on the dose level alone. A formula has been derived to establish mean physical dose constraints such that they are mean BED equivalent to a reference treatment scheme. This formula constitutes a modified BED equation where the influence of the spatial dose distribution is summarized in a single parameter, the dose shape factor. To quantify effects we analyzed 24 liver cancer patients for whom both proton and photon IMRT treatment plans were available. The results show that the standard BED equation—neglecting the spatial dose distribution—can overestimate mean dose tolerances for hypofractionated treatments by up to 20%. The shape difference between photon and proton dose distributions can cause 30-40% differences in mean physical dose for plans having identical mean BEDs. Converting hypofractionated, 5/15-fraction proton doses to mean BED equivalent photon doses in traditional 35-fraction regimens resulted in up to 10 Gy higher doses than applying the standard BED formula. The dose shape effect should be accounted for to avoid overestimation of mean dose tolerances, particularly when estimating constraints for hypofractionated regimens. Additionally, tolerances established for one treatment modality cannot necessarily be applied to other modalities with drastically different dose distributions, such as proton therapy. Last, protons may only allow marginal (5-10%) dose escalation if a fraction-size adjusted organ mean dose is constraining instead of a physical dose.

Performance evaluation of an improved optical computed tomography polymer gel dosimeter system for 3D dose verification of static and dynamic phantom deliveries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopatiuk-Tirpak, O.; Langen, K. M.; Meeks, S. L.

2008-09-15

The performance of a next-generation optical computed tomography scanner (OCTOPUS-5X) is characterized in the context of three-dimensional gel dosimetry. Large-volume (2.2 L), muscle-equivalent, radiation-sensitive polymer gel dosimeters (BANG-3) were used. Improvements in scanner design leading to shorter acquisition times are discussed. The spatial resolution, detectable absorbance range, and reproducibility are assessed. An efficient method for calibrating gel dosimeters using the depth-dose relationship is applied, with photon- and electron-based deliveries yielding equivalent results. A procedure involving a preirradiation scan was used to reduce the edge artifacts in reconstructed images, thereby increasing the useful cross-sectional area of the dosimeter by nearly amore » factor of 2. Dose distributions derived from optical density measurements using the calibration coefficient show good agreement with the treatment planning system simulations and radiographic film measurements. The feasibility of use for motion (four-dimensional) dosimetry is demonstrated on an example comparing dose distributions from static and dynamic delivery of a single-field photon plan. The capability to visualize three-dimensional dose distributions is also illustrated.« less

Testing for Additivity in Chemical Mixtures Using a Fixed-Ratio Ray Design and Statistical Equivalence Testing Methods

EPA Science Inventory

Fixed-ratio ray designs have been used for detecting and characterizing interactions of large numbers of chemicals in combination. Single chemical dose-response data are used to predict an “additivity curve” along an environmentally relevant ray. A “mixture curve” is estimated fr...

OSL studies of local bricks for retrospective dosimetric application

NASA Astrophysics Data System (ADS)

Singh, A. K.; Menon, S. N.; Kadam, S. Y.; Koul, D. K.; Datta, D.

2016-09-01

Luminescence properties of quartz extracted from bricks has been reported worldwide for its use in dose estimation in case of nuclear or radiological accident. Accordingly, in this study the feasibility of utilizing the optically stimulated luminescence (OSL) emission of quartz extracted from red bricks collected from three different locations in and around Mumbai, India for retrospective dosimetry was explored. Thermoluminescence and OSL characterization of the samples were carried out. The growth curve, thermal stability and equivalent dose plateau of the OSL signal suggested the signals to be well behaving. Subsequently, the dose recovery tests carried for different administered doses, using single aliquot regenerative protocol, demonstrated the feasibility of the OSL emissions of these samples for dose evaluation in retrospective dosimetry.

Response of a tissue equivalent proportional counter to neutrons

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Robbins, D. E.; Gibbons, F.; Braby, L. A.

2002-01-01

The absorbed dose as a function of lineal energy was measured at the CERN-EC Reference-field Facility (CERF) using a 512-channel tissue equivalent proportional counter (TEPC), and neutron dose equivalent response evaluated. Although there are some differences, the measured dose equivalent is in agreement with that measured by the 16-channel HANDI tissue equivalent counter. Comparison of TEPC measurements with those made by a silicon solid-state detector for low linear energy transfer particles produced by the same beam, is presented. The measurements show that about 4% of dose equivalent is delivered by particles heavier than protons generated in the conducting tissue equivalent plastic. c2002 Elsevier Science Ltd. All rights reserved.

Water equivalent path length measurement in proton radiotherapy using time resolved diode dosimetry

PubMed Central

Gottschalk, B.; Tang, S.; Bentefour, E. H.; Cascio, E. W.; Prieels, D.; Lu, H.-M.

2011-01-01

Purpose: To verify water equivalent path length (WEPL) before treatment in proton radiotherapy using time resolved in vivo diode dosimetry. Methods: Using a passively scattered range modulated proton beam, the output of a diode driving a fast current-to-voltage amplifier is recorded at a number of depths in a water tank. At each depth, a burst of overlapping single proton pulses is observed. The rms duration of the burst is computed and the resulting data set is fitted with a cubic polynomial. Results: When the diode is subsequently set to an arbitrary depth and the polynomial is used as a calibration curve, the “unknown” depth is determined within 0.3 mm rms. Conclusions: A diode or a diode array, placed (for instance) in the rectum in conjunction with a rectal balloon, can potentially determine the WEPL at that point, just prior to treatment, with submillimeter accuracy, allowing the beam energy to be adjusted. The associated unwanted dose is about 0.2% of a typical single fraction treatment dose. PMID:21626963

Correlation of electron and proton irradiation-induced damage in InP solar cells

NASA Technical Reports Server (NTRS)

Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

1996-01-01

The measured degradation of epitaxial shallow homojunction n(+)/p InP solar cells under 1 MeV electron irradiation is correlated with that measured under 3 MeV proton irradiation based on 'displacement damage dose'. The measured data is analyzed as a function of displacement damage dose from which an electron to proton dose equivalency ratio is determined which enables the electron and proton degradation data to be described by a single degradation curve. It is discussed how this single curve can be used to predict the cell degradation under irradiation by any particle energy. The degradation curve is used to compare the radiation response of InP and GaAs/Ge cells on an absolute damage energy scale. The comparison shows InP to be inherently more resistant to displacement damage deposition than the GaAs/Ge.

Salicylate-induced enzymuria: comparison with other anti-inflammatory agents.

PubMed

Proctor, R A; Kunin, C M

1978-12-01

N-acetyl-beta glucosaminidase (NAG) enzymuria was used as a marker of renal injury in patients with rheumatic disease. An elevated NAG level was particularly common in patients receiving gold or aspirin therapy. The multiplicity of drugs received and the unknown role of underlying disease in these patients led to a study in healthy volunteers. Customary therapeutic doses of aspirin, choline salicylate, ibuprofen, indomethacin and acetaminophen did not produce enzymuria. Large single doses of salicylates equivalent to 6 tablets of aspirin consistently did produce enzymuria. The size of the individual dose in relation to body weight was more important than the total daily dose. NAG enzymuria appears to be a sensitive tool for identifying potentially nephrotoxic drugs.

10 CFR 835.203 - Combining internal and external equivalent doses.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Combining internal and external equivalent doses. 835.203 Section 835.203 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and External Exposure § 835.203 Combining internal and external equivalent doses. (a) The total effective dose...

Single dose intravenous methyl prednisolone versus oral prednisolone in Bell's palsy: A randomized controlled trial

PubMed Central

Giri, Prithvi; Garg, Ravindra Kumar; Singh, Maneesh Kumar; Verma, Rajesh; Malhotra, Hardeep Singh; Sharma, Praveen Kumar

2015-01-01

Objectives: Corticosteroids have been used in the treatment of Bell's palsy and several other postinfectious neurological conditions. We hypothesized that administration of a single dose of intravenous (IV) methylprednisolone might be an effective alternative to oral prednisolone. Materials and Methods: In this open label, randomized trial, patients with acute Bell's palsy were randomized into two groups. One group received single dose (500 mg) of IV methylprednisolone while the other group received 10 days of oral prednisone. Outcome was assessed at 1 and 3 months with House–Brackmann scale. Results: At 3 months, 93 (79.48%) patients had completely recovered. IV methylprednisolone and oral prednisolone groups had similar recovery rates (80% vs. 78.33%, P > 0.05). Patients with Grade 2 and 3 recovered completely. In patients with Grade 6, the recovery rate was 20%. A better outcome was observed if corticosteroids were administered within 3 days of onset of palsy. Conclusion: Intravenous methylprednisolone and oral prednisolone showed equivalent benefit in patients with acute Bell's palsy. PMID:25878371

Estimation and comparison of effective dose (E) in standard chest CT by organ dose measurements and dose-length-product methods and assessment of the influence of CT tube potential (energy dependency) on effective dose in a dual-source CT.

PubMed

Paul, Jijo; Banckwitz, Rosemarie; Krauss, Bernhard; Vogl, Thomas J; Maentele, Werner; Bauer, Ralf W

2012-04-01

To determine effective dose (E) during standard chest CT using an organ dose-based and a dose-length-product-based (DLP) approach for four different scan protocols including high-pitch and dual-energy in a dual-source CT scanner of the second generation. Organ doses were measured with thermo luminescence dosimeters (TLD) in an anthropomorphic male adult phantom. Further, DLP-based dose estimates were performed by using the standard 0.014mSv/mGycm conversion coefficient k. Examinations were performed on a dual-source CT system (Somatom Definition Flash, Siemens). Four scan protocols were investigated: (1) single-source 120kV, (2) single-source 100kV, (3) high-pitch 120kV, and (4) dual-energy with 100/Sn140kV with equivalent CTDIvol and no automated tube current modulation. E was then determined following recommendations of ICRP publication 103 and 60 and specific k values were derived. DLP-based estimates differed by 4.5-16.56% and 5.2-15.8% relatively to ICRP 60 and 103, respectively. The derived k factors calculated from TLD measurements were 0.0148, 0.015, 0.0166, and 0.0148 for protocol 1, 2, 3 and 4, respectively. Effective dose estimations by ICRP 103 and 60 for single-energy and dual-energy protocols show a difference of less than 0.04mSv. Estimates of E based on DLP work equally well for single-energy, high-pitch and dual-energy CT examinations. The tube potential definitely affects effective dose in a substantial way. Effective dose estimations by ICRP 103 and 60 for both single-energy and dual-energy examinations differ not more than 0.04mSv. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The effect of dose enhancement near metal interfaces on synthetic diamond based X-ray dosimeters

NASA Astrophysics Data System (ADS)

Alamoudi, D.; Lohstroh, A.; Albarakaty, H.

2017-11-01

This study investigates the effects of dose enhancement on the photocurrent performance at metallic interfaces in synthetic diamond detectors based X-ray dosimeters as a function of bias voltages. Monte Carlo (MC) simulations with the BEAMnrc code were carried out to simulate the dose enhancement factor (DEF) and compared against the equivalent photocurrent ratio from experimental investigations. The MC simulation results show that the sensitive region for the absorbed dose distribution covers a few micrometers distances from the interface. Experimentally, two single crystals (SC) and one polycrystalline (PC) synthetic diamond samples were fabricated into detectors with carbon based electrodes by boron and carbon ion implantation. Subsequently; the samples were each mounted inside a tissue equivalent encapsulation to minimize unintended fluence perturbation. Dose enhancement was generated by placing copper, lead or gold near the active volume of the detectors using 50 kVp and 100 kVp X-rays relevant for medical dosimetry. The results show enhancement in the detectors' photocurrent performance when different metals are butted up to the diamond bulk as expected. The variation in the photocurrent measurement depends on the type of diamond samples, their electrodes' fabrication and the applied bias voltages indicating that the dose enhancement near the detector may modify their electronic performance.

Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy

NASA Astrophysics Data System (ADS)

Hälg, R. A.; Besserer, J.; Boschung, M.; Mayer, S.; Lomax, A. J.; Schneider, U.

2014-05-01

In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

Measurements of the neutron dose equivalent for various radiation qualities, treatment machines and delivery techniques in radiation therapy.

PubMed

Hälg, R A; Besserer, J; Boschung, M; Mayer, S; Lomax, A J; Schneider, U

2014-05-21

In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

Evaluation of a novel triple-channel radiochromic film analysis procedure using EBT2.

PubMed

van Hoof, Stefan J; Granton, Patrick V; Landry, Guillaume; Podesta, Mark; Verhaegen, Frank

2012-07-07

A novel approach to read out radiochromic film was introduced recently by the manufacturer of GafChromic film. In this study, the performance of this triple-channel film dosimetry method was compared against the conventional single-red-channel film dosimetry procedure, with and without inclusion of a pre-irradiation (pre-IR) film scan, using EBT2 film and kilo- and megavoltage photon beams up to 10 Gy. When considering regions of interest averaged doses, the triple-channel method and both single-channel methods produced equivalent results. Absolute dose discrepancies between the triple-channel method, both single-channel methods and the treatment planning system calculated dose values, were no larger than 5 cGy for dose levels up to 2.2 Gy. Signal to noise in triple-channel dose images was found to be similar to signal to noise in single-channel dose images. The accuracy of resulting dose images from the triple- and single-channel methods with inclusion of pre-IR film scan was found to be similar. Results of a comparison of EBT2 data from a kilovoltage depth dose experiment to corresponding Monte Carlo depth dose data produced dose discrepancies of 9.5 ± 12 cGy and 7.6 ± 6 cGy for the single-channel method with inclusion of a pre-IR film scan and the triple-channel method, respectively. EBT2 showed to be energy sensitive at low kilovoltage energies with response differences of 11.9% and 15.6% in the red channel at 2 Gy between 50-225 kVp and 80-225 kVp photon spectra, respectively. We observed that the triple-channel method resulted in non-uniformity corrections of ±1% and consistency values of 0-3 cGy for the batches and dose levels studied. Results of this study indicate that the triple-channel radiochromic film read-out method performs at least as well as the single-channel method with inclusion of a pre-IR film scan, reduces film non-uniformity and saves time with elimination of a pre-IR film scan.

TU-H-BRC-08: Use and Validation of Flexible 3D Printed Tissue Compensators for Post-Mastectomy Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Craft, D; Kry, S; Salehpour, M

Purpose: Patient-specific tissue equivalent compensators can be used for post-mastectomy radiation therapy (PMRT) to achieve homogenous dose distributions with single-field treatments. However, current fabrication methods are time consuming and expensive. 3D-printing technology could overcome these limitations. The purposes of this study were to [1] evaluate materials for 3D-printed compensators [2] design and print a compensator to achieve a uniform thickness to a clinical target volume (CTV), and [3] demonstrate that a single-field electron compensator plan is a clinically feasible treatment option for PMRT. Methods: Blocks were printed with three materials; print accuracy, density, Hounsfield units (HU), and percent depth dosesmore » (PDD) were evaluated. For a CT scan of an anthropomorphic phantom, we used a ray-tracing method to design a compensator that achieved uniform thickness from compensator surface to CTV. The compensator was printed with flexible tissue equivalent material whose physical and radiological properties were most similar to soft tissue. A single-field electron compensator plan was designed and compared with two standard-of-care techniques. The compensator plan was validated with thermoluminescent dosimeter (TLD) measurements. Results: We identified an appropriate material for 3D-printed compensators that had high print accuracy (99.6%) and was similar to soft tissue; density was 1.04, HU was - 45 ± 43, and PDD curves agreed with clinical curves within 3 mm. We designed and printed a compensator that conformed well to the phantom surface and created a uniform thickness to the CTV. In-house fabrication was simple and inexpensive (<$75). Compared with the two standard plans, the compensator plan resulted in overall more homogeneous dose distributions and performed similarly in terms of lung/heart doses and 90% isodose coverage of the CTV. TLD measurements agreed well with planned doses (within 5 %). Conclusions: We have demonstrated that 3D-printed compensators make single-field electron therapy a clinically feasible treatment option for PMRT.« less

Narcotic Use and Postoperative Doctor Shopping in the Orthopaedic Trauma Population.

PubMed

Morris, Brent J; Zumsteg, Justin W; Archer, Kristin R; Cash, Brian; Mir, Hassan R

2014-08-06

The negative consequences of narcotic use and diversion for nonmedical use are on the rise. A growing number of narcotic abusers obtain narcotic prescriptions from multiple providers ("doctor shopping"). This study sought to determine the effects of multiple postoperative narcotic providers on the number of narcotic prescriptions, duration of narcotics, and morphine equivalent dose per day in the orthopaedic trauma population. Our prospective cohort study used the state-controlled substance monitoring database to identify all narcotic prescriptions filled three months prior to admission and six months following discharge for enrolled patients. Patients were assigned into two groups: a single narcotic provider group with prescriptions only from the treating surgeon (or extenders) or a multiple narcotic provider group with prescriptions from both the treating surgeon and an additional provider or providers. Complete data were available for 130 of 151 eligible patients. Preoperative narcotic use, defined by three or more narcotic prescriptions within three months of admission, was noted in 8.5% of patients. Overall, 20.8% of patients sought multiple narcotic providers postoperatively. There were significant increases in postoperative narcotic prescriptions (p < 0.001) between the single narcotic provider group (two prescriptions) and the multiple narcotic provider group (seven prescriptions), in duration of postoperative narcotic use (p < 0.001) between the single narcotic provider group (twenty-eight days) and the multiple narcotic provider group (110 days), and in morphine equivalent dose per day (p = 0.002) between the single narcotic provider group (26 mg) and the multiple narcotic provider group (43 mg). Patients with a high school education or less were 3.2 times more likely to seek multiple providers (p = 0.02), and patients with a history of preoperative narcotic use were 4.5 times more likely to seek multiple providers (p < 0.001). There is a 20.8% prevalence of postoperative doctor shopping in the orthopaedic trauma population. Patients with multiple postoperative narcotic providers had a significant increase in postoperative narcotic prescriptions, duration of narcotics, and morphine equivalent dose per day. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

Emphysema quantification and lung volumetry in chest X-ray equivalent ultralow dose CT - Intra-individual comparison with standard dose CT.

PubMed

Messerli, Michael; Ottilinger, Thorsten; Warschkow, René; Leschka, Sebastian; Alkadhi, Hatem; Wildermuth, Simon; Bauer, Ralf W

2017-06-01

To determine whether ultralow dose chest CT with tin filtration can be used for emphysema quantification and lung volumetry and to assess differences in emphysema measurements and lung volume between standard dose and ultralow dose CT scans using advanced modeled iterative reconstruction (ADMIRE). 84 consecutive patients from a prospective, IRB-approved single-center study were included and underwent clinically indicated standard dose chest CT (1.7±0.6mSv) and additional single-energy ultralow dose CT (0.14±0.01mSv) at 100kV and fixed tube current at 70mAs with tin filtration in the same session. Forty of the 84 patients (48%) had no emphysema, 44 (52%) had emphysema. One radiologist performed fully automated software-based pulmonary emphysema quantification and lung volumetry of standard and ultralow dose CT with different levels of ADMIRE. Friedman test and Wilcoxon rank sum test were used for multiple comparison of emphysema and lung volume. Lung volumes were compared using the concordance correlation coefficient. The median low-attenuation areas (LAA) using filtered back projection (FBP) in standard dose was 4.4% and decreased to 2.6%, 2.1% and 1.8% using ADMIRE 3, 4, and 5, respectively. The median values of LAA in ultralow dose CT were 5.7%, 4.1% and 2.4% for ADMIRE 3, 4, and 5, respectively. There was no statistically significant difference between LAA in standard dose CT using FBP and ultralow dose using ADMIRE 4 (p=0.358) as well as in standard dose CT using ADMIRE 3 and ultralow dose using ADMIRE 5 (p=0.966). In comparison with standard dose FBP the concordance correlation coefficients of lung volumetry were 1.000, 0.999, and 0.999 for ADMIRE 3, 4, and 5 in standard dose, and 0.972 for ADMIRE 3, 4 and 5 in ultralow dose CT. Ultralow dose CT at chest X-ray equivalent dose levels allows for lung volumetry as well as detection and quantification of emphysema. However, longitudinal emphysema analyses should be performed with the same scan protocol and reconstruction algorithms for reproducibility. Copyright © 2017 Elsevier B.V. All rights reserved.

AIR insulin capsules of different dose strengths may be combined to yield equivalent pharmacokinetics and glucodynamics.

PubMed

de la Peña, Amparo; Seger, Mary; Rave, Klaus; Heinemann, Lutz; Silverman, Bernard; Muchmore, Douglas B

2009-09-01

In order to assess pharmacokinetic (PK) and glucodynamic (GD) attributes relevant to the end user of an inhaled insulin, this study examined the exposure and GD effect of doses of AIR inhaled insulin (Eli Lilly and Co., Indianapolis, IN) (AIR is a registered trademark of Alkermes, Inc., Cambridge, MA) by combining capsules of different strengths in healthy subjects. Fifty-nine healthy, nonsmoking, male or female subjects with normal pulmonary function were enrolled in an open-label, randomized, crossover study. Subjects underwent up to five euglycemic glucose clamp procedures, separated by 5-18 days. The five AIR insulin treatments tested included one 6 unit-equivalent (U-eq) capsule containing 2.6 mg of insulin, three 2 U-eq (0.9 mg) capsules (2.7 mg total), one 10 U-eq (3.9 mg) capsule, one 6 U-eq capsule plus two 2 U-eq capsules (4.4 mg total), and two 10 U-eq capsules (7.8 mg total). Samples for PK and GD assessments were taken up to 10 h post-dose. Based on both PK (area under the curve from time 0 to time of return to baseline and maximum concentration) and GD (total amount of glucose infused and maximum glucose infusion rate) responses, administration of a 6 U-eq capsule was equivalent to three 2 U-eq capsules; 90% confidence intervals for the ratios were contained within the interval (0.8, 1.25). Similarly, both overall exposure and glucodynamic response after administration of a 10 U-eq capsule were comparable to the 6 U-eq plus two 2 U-eq capsule combination. AIR insulin exhibited PK dose proportionality and dose-dependent increases in GD responses over the 2.6-7.8 mg dose range. AIR insulin exhibited dose strength interchangeability and dose proportionality after single-dose administration in healthy subjects.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cederkrantz, Elin; Andersson, Håkan; Bernhardt, Peter

Purpose: Ovarian cancer is often diagnosed at an advanced stage with dissemination in the peritoneal cavity. Most patients achieve clinical remission after surgery and chemotherapy, but approximately 70% eventually experience recurrence, usually in the peritoneal cavity. To prevent recurrence, intraperitoneal (i.p.) targeted α therapy has been proposed as an adjuvant treatment for minimal residual disease after successful primary treatment. In the present study, we calculated absorbed and relative biological effect (RBE)-weighted (equivalent) doses in relevant normal tissues and estimated the effective dose associated with i.p. administration of {sup 211}At-MX35 F(ab'){sub 2}. Methods and Materials: Patients in clinical remission after salvage chemotherapymore » for peritoneal recurrence of ovarian cancer underwent i.p. infusion of {sup 211}At-MX35 F(ab'){sub 2}. Potassium perchlorate was given to block unwanted accumulation of {sup 211}At in thyroid and other NIS-containing tissues. Mean absorbed doses to normal tissues were calculated from clinical data, including blood and i.p. fluid samples, urine, γ-camera images, and single-photon emission computed tomography/computed tomography images. Extrapolation of preclinical biodistribution data combined with clinical blood activity data allowed us to estimate absorbed doses in additional tissues. The equivalent dose was calculated using an RBE of 5 and the effective dose using the recommended weight factor of 20. All doses were normalized to the initial activity concentration of the infused therapy solution. Results: The urinary bladder, thyroid, and kidneys (1.9, 1.8, and 1.7 mGy per MBq/L) received the 3 highest estimated absorbed doses. When the tissue-weighting factors were applied, the largest contributors to the effective dose were the lungs, stomach, and urinary bladder. Using 100 MBq/L, organ equivalent doses were less than 10% of the estimated tolerance dose. Conclusion: Intraperitoneal {sup 211}At-MX35 F(ab'){sub 2} treatment is potentially a well-tolerated therapy for locally confined microscopic ovarian cancer. Absorbed doses to normal organs are low, but because the effective dose potentially corresponds to a risk of treatment-induced carcinogenesis, optimization may still be valuable.« less

Dose estimation to eye lens of industrial gamma radiography workers using the Monte Carlo method.

PubMed

de Lima, Alexandre Roza; Hunt, John Graham; Da Silva, Francisco Cesar Augusto

2017-12-01

The ICRP Statement on Tissue Reactions (2011), based on epidemiological evidence, recommended a reduction for the eye lens equivalent dose limit from 150 to 20 mSv per year. This paper presents mainly the dose estimations received by industrial gamma radiography workers, during planned or accidental exposure to the eye lens, Hp(10) and effective dose. A Brazilian Visual Monte Carlo Dose Calculation program was used and two relevant scenarios were considered. For the planned exposure situation, twelve radiographic exposures per day for 250 days per year, which leads to a direct exposure of 10 h per year, were considered. The simulation was carried out using a 192 Ir source with 1.0 TBq of activity; a source/operator distance between 5 and 10 m and placed at heights of 0.02 m, 1 m and 2 m, and an exposure time of 12 s. Using a standard height of 1 m, the eye lens doses were estimated as being between 16.3 and 60.3 mGy per year. For the accidental exposure situation, the same radionuclide and activity were used, but in this case the doses were calculated with and without a collimator. The heights above ground considered were 1.0 m, 1.5 m and 2.0 m; the source/operator distance was 40 cm, and the exposure time 74 s. The eye lens doses at 1.5 m were 12.3 and 0.28 mGy without and with a collimator, respectively. The conclusions were that: (1) the estimated doses show that the 20 mSv annual limit for eye lens equivalent dose can directly impact industrial gamma radiography activities, mainly in industries with high number of radiographic exposures per year; (2) the risk of lens opacity has a low probability for a single accident, but depending on the number of accidental exposures and the dose levels found in planned exposures, the threshold dose can easily be exceeded during the professional career of an industrial radiography operator, and; (3) in a first approximation, Hp(10) can be used to estimate the equivalent dose to the eye lens.

A general dual-bolus approach for quantitative DCE-MRI.

PubMed

Kershaw, Lucy E; Cheng, Hai-Ling Margaret

2011-02-01

To present a dual-bolus technique for quantitative dynamic contrast-enhanced MRI (DCE-MRI) and show that it can give an arterial input function (AIF) measurement equivalent to that from a single-bolus protocol. Five rabbits were imaged using a dual-bolus technique applicable for high-resolution DCE-MRI, incorporating a time resolved imaging of contrast kinetics (TRICKS) sequence for rapid temporal sampling. AIFs were measured from both the low-dose prebolus and the high-dose main bolus in the abdominal aorta. In one animal, TRICKS and fast spoiled gradient echo (FSPGR) acquisitions were compared. The scaled prebolus AIF was shown to match the main bolus AIF, with 95% confidence intervals overlapping for fits of gamma-variate functions to the first pass and linear fits to the washout phase, with the exception of one case. The AIFs measured using TRICKS and FSPGR were shown to be equivalent in one animal. The proposed technique can capture even the rapid circulation kinetics in the rabbit aorta, and the scaled prebolus AIF is equivalent to the AIF from a high-dose injection. This allows separate measurements of the AIF and tissue uptake curves, meaning that each curve can then be acquired using a protocol tailored to its specific requirements. Copyright © 2011 Elsevier Inc. All rights reserved.

Chlordecone Altered Hepatic Disposition of [14C]Cholesterol and Plasma Cholesterol Distribution but not SR-BI or ABCG8 Proteins in Livers of C57BL/6 Mice

PubMed Central

Lee, Junga; Scheri, Richard C.; Curtis, Lawrence R.

2011-01-01

Organochlorine (OC) insecticides continue to occur in tissues of humans and wildlife throughout the world although they were banned in the United States a few decades ago. Low doses of the OC insecticide chlordecone (CD) alter hepatic disposition of lipophilic xenobiotics and perturb lipid homeostasis in rainbow trout, mice and rats. CD pretreatment altered tissue and hepatic subcellular distribution of exogenous [14C]cholesterol (CH) equivalents 4 and 16 h after a bolus intraperitoneal (ip) injection of 5 ml corn oil/kg that contained 10 mg CH/kg. CD pretreatment altered tissue distribution of exogenously administered [14C]CH by decreased hepatic and renal accumulation, and increased biliary excretion up to 300%. Biliary excretion of polar [14C]CH metabolites was not altered by CD. CD pretreatment decreased subcellular distribution of [14C]CH equivalents in hepatic cytosol and microsomes and lipoprotein-rich fraction-to-homogenate ratio. CD pretreatment increased the ratio of [14C]CH equivalents in high density lipoprotein (HDL) to that in plasma and reduced [14C]CH equivalents in the non-HDL fraction 4 h after a bolus lipid dose. CD pretreatment increased plasma non-HDL total CH by 80% 4 h after a bolus lipid dose. Scavenger receptor class B type I (SR-BI) and ATPbinding cassette transporter G8 (ABCG8) proteins were quantified by western blotting in hepatic membranes from control and CD treated mice. Liver membrane contents of SR-BI and ABCG8 proteins were unchanged by CD pretreatment. The data demonstrated that a single dose of CD altered CH homeostasis and lipoprotein metabolism. PMID:18387646

Chlordecone altered hepatic disposition of [14C]cholesterol and plasma cholesterol distribution but not SR-BI or ABCG8 proteins in livers of C57BL/6 mice.

PubMed

Lee, Junga; Scheri, Richard C; Curtis, Lawrence R

2008-06-15

Organochlorine (OC) insecticides continue to occur in tissues of humans and wildlife throughout the world although they were banned in the United States a few decades ago. Low doses of the OC insecticide chlordecone (CD) alter hepatic disposition of lipophilic xenobiotics and perturb lipid homeostasis in rainbow trout, mice and rats. CD pretreatment altered tissue and hepatic subcellular distribution of exogenous [(14)C]cholesterol (CH) equivalents 4 and 16 h after a bolus intraperitoneal (ip) injection of 5 ml corn oil/kg that contained 10 mg CH/kg. CD pretreatment altered tissue distribution of exogenously administered [(14)C]CH by decreased hepatic and renal accumulation, and increased biliary excretion up to 300%. Biliary excretion of polar [(14)C]CH metabolites was not altered by CD. CD pretreatment decreased subcellular distribution of [(14)C]CH equivalents in hepatic cytosol and microsomes and lipoprotein-rich fraction-to-homogenate ratio. CD pretreatment increased the ratio of [(14)C]CH equivalents in high density lipoprotein (HDL) to that in plasma and reduced [(14)C]CH equivalents in the non-HDL fraction 4 h after a bolus lipid dose. CD pretreatment increased plasma non-HDL total CH by 80% 4 h after a bolus lipid dose. Scavenger receptor class B type I (SR-BI) and ATP-binding cassette transporter G8 (ABCG8) proteins were quantified by western blotting in hepatic membranes from control and CD treated mice. Liver membrane contents of SR-BI and ABCG8 proteins were unchanged by CD pretreatment. The data demonstrated that a single dose of CD altered CH homeostasis and lipoprotein metabolism.

42 CFR 82.5 - Definition of terms used in this part.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Illness Compensation Program Act of 2000, 42 U.S.C. 7384-7385 [1994, supp. 2001]. (i) Equivalent dose is... equivalent dose that is received from radiation sources outside of the body. (k) Internal dose means that portion of the equivalent dose that is received from radioactive materials taken into the body. (l) NIOSH...

In vivo and phantom measurements of the secondary photon and neutron doses for prostate patients undergoing 18 MV IMRT.

PubMed

Reft, Chester S; Runkel-Muller, Renate; Myrianthopoulos, Leon

2006-10-01

For intensity modulated radiation therapy (IMRT) treatments 6 MV photons are typically used, however, for deep seated tumors in the pelvic region, higher photon energies are increasingly being employed. IMRT treatments require more monitor units (MU) to deliver the same dose as conformal treatments, causing increased secondary radiation to tissues outside the treated area from leakage and scatter, as well as a possible increase in the neutron dose from photon interactions in the machine head. Here we provide in vivo patient and phantom measurements of the secondary out-of-field photon radiation and the neutron dose equivalent for 18 MV IMRT treatments. The patients were treated for prostate cancer with 18 MV IMRT at institutions using different therapy machines and treatment planning systems. Phantom exposures at the different facilities were used to compare the secondary photon and neutron dose equivalent between typical IMRT delivered treatment plans with a six field three-dimensional conformal radiotherapy (3DCRT) plan. For the in vivo measurements LiF thermoluminescent detectors (TLDs) and Al2O3 detectors using optically stimulated radiation were used to obtain the photon dose and CR-39 track etch detectors were used to obtain the neutron dose equivalent. For the phantom measurements a Bonner sphere (25.4 cm diameter) containing two types of TLDs (TLD-600 and TLD-700) having different thermal neutron sensitivities were used to obtain the out-of-field neutron dose equivalent. Our results showed that for patients treated with 18 MV IMRT the photon dose equivalent is greater than the neutron dose equivalent measured outside the treatment field and the neutron dose equivalent normalized to the prescription dose varied from 2 to 6 mSv/Gy among the therapy machines. The Bonner sphere results showed that the ratio of neutron equivalent doses for the 18 MV IMRT and 3DCRT prostate treatments scaled as the ratio of delivered MUs. We also observed differences in the measured neutron dose equivalent among the three therapy machines for both the in vivo and phantom exposures.

Dose Equivalents for Second-Generation Antipsychotic Drugs: The Classical Mean Dose Method

PubMed Central

Leucht, Stefan; Samara, Myrto; Heres, Stephan; Patel, Maxine X.; Furukawa, Toshi; Cipriani, Andrea; Geddes, John; Davis, John M.

2015-01-01

Background: The concept of dose equivalence is important for many purposes. The classical approach published by Davis in 1974 subsequently dominated textbooks for several decades. It was based on the assumption that the mean doses found in flexible-dose trials reflect the average optimum dose which can be used for the calculation of dose equivalence. We are the first to apply the method to second-generation antipsychotics. Methods: We searched for randomized, double-blind, flexible-dose trials in acutely ill patients with schizophrenia that examined 13 oral second-generation antipsychotics, haloperidol, and chlorpromazine (last search June 2014). We calculated the mean doses of each drug weighted by sample size and divided them by the weighted mean olanzapine dose to obtain olanzapine equivalents. Results: We included 75 studies with 16 555 participants. The doses equivalent to 1 mg/d olanzapine were: amisulpride 38.3 mg/d, aripiprazole 1.4 mg/d, asenapine 0.9 mg/d, chlorpromazine 38.9 mg/d, clozapine 30.6 mg/d, haloperidol 0.7 mg/d, quetiapine 32.3mg/d, risperidone 0.4mg/d, sertindole 1.1 mg/d, ziprasidone 7.9 mg/d, zotepine 13.2 mg/d. For iloperidone, lurasidone, and paliperidone no data were available. Conclusions: The classical mean dose method is not reliant on the limited availability of fixed-dose data at the lower end of the effective dose range, which is the major limitation of “minimum effective dose methods” and “dose-response curve methods.” In contrast, the mean doses found by the current approach may have in part depended on the dose ranges chosen for the original trials. Ultimate conclusions on dose equivalence of antipsychotics will need to be based on a review of various methods. PMID:25841041

Measurement of doses to the extremities of nuclear medicine staff

NASA Astrophysics Data System (ADS)

Shousha, Hany A.; Farag, Hamed; Hassan, Ramadan A.

2010-01-01

Medical uses of ionizing radiation now represent>95% of all man-made radiation exposure, and is the largest single radiation source after natural background radiation. Therefore, it is important to quantify the amount of radiation received by occupational individuals to optimize the working conditions for staff, and further, to compare doses in different departments to ensure compatibility with the recommended standards. For some groups working with unsealed sources in nuclear medicine units, the hands are more heavily exposed to ionizing radiation than the rest of the body. A personal dosimetry service runs extensively in Egypt. But doses to extremities have not been measured to a wide extent. The purpose of this study was to investigate the equivalent radiation doses to the fingers for five different nuclear medicine staff occupational groups for which heavy irradiation of the hands was suspected. Finger doses were measured for (1) nuclear medicine physicians, (2) technologists, (3) nurses and (4) physicists. The fifth group contains three technicians handling 131I, while the others handled 99mTc. Each staff member working with the radioactive material wore two thermoluminescent dosimeters (TLDs) during the whole testing period, which lasted from 1 to 4 weeks. Staff performed their work on a regular basis throughout the month, and mean annual doses were calculated for these groups. Results showed that the mean equivalent doses to the fingers of technologist, nurse and physicist groups were 30.24±14.5, 30.37±17.5 and 16.3±7.7 μSv/GBq, respectively. Equivalent doses for the physicians could not be calculated per unit of activity because they did not handle the radiopharmaceuticals directly. Their doses were reported in millisieverts (mSv) that accumulated in one week. Similarly, the dose to the fingers of individuals in Group 5 was estimated to be 126.13±38.2 μSv/GBq. The maximum average finger dose, in this study, was noted in the technologists who handled therapeutic 131I (2.5 mSv). In conclusion, the maximum expected annual dose to extremities is less than the annual limit (500 mSv/y).

Effects of selected materials and geometries on the beta dose equivalent rate in a tissue equivalent phantom immersed in infinite clouds of 133Xe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piltingsrud, H.V.; Gels, G.L.

1986-06-01

Most calculations of dose equivalent (D.E.) rates at 70-micron tissue depths in tissue equivalent (T.E.) phantoms from infinite clouds (radius exceeds maximum beta range in air) of /sup 133/Xe do not consider the possible effects of clothing overlays. Consequently, a series of measurements were made using a 1-mm-thick plastic scintillation detector assembly mounted in a tissue equivalent (T.E.) phantom with an overlay of 70 micron of T.E. material. This assembly was placed in an infinite cloud containing a known concentration of /sup 133/Xe. Material samples were placed at selected distances from the detector phantom, both individually and in various combinations.more » Pulse-height spectra resulting from beta radiations were converted to relative D.E. rates at a 70-micron tissue depth. The relative D.E. rates were reduced from values with no clothing cover by as little as 45% when placing a single thin nylon cloth 1 cm from the phantom, to 94% for a T-shirt material plus wool material plus denim placed 1/2, 1 and 3 cm, respectively, from the phantom. The results indicate that even loosely fitting clothing can have an important effect on reducing the D.E. rate. Close-fitting clothing appears to provide better protection.« less

Changes in ambient dose equivalent rates around roads at Kawamata town after the Fukushima accident.

PubMed

Kinase, Sakae; Sato, Satoshi; Sakamoto, Ryuichi; Yamamoto, Hideaki; Saito, Kimiaki

2015-11-01

Changes in ambient dose equivalent rates noted through vehicle-borne surveys have elucidated ecological half-lives of radioactive caesium in the environment. To confirm that the ecological half-lives are appropriate for predicting ambient dose equivalent rates within living areas, it is important to ascertain ambient dose equivalent rates on/around roads. In this study, radiation monitoring on/around roads at Kawamata town, located about 37 km northwest of the Fukushima Daiichi Nuclear Power Plant, was performed using monitoring vehicles and survey meters. It was found that the ambient dose equivalent rates around roads were higher than those on roads as of October 2012. And withal the ecological half-lives on roads were essentially consistent with those around roads. With dose predictions using ecological half-lives on roads, it is necessary to make corrections to ambient dose equivalent rates through the vehicle-borne surveys against those within living areas. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Heavy ion contributions to organ dose equivalent for the 1977 galactic cosmic ray spectrum

NASA Astrophysics Data System (ADS)

Walker, Steven A.; Townsend, Lawrence W.; Norbury, John W.

2013-05-01

Estimates of organ dose equivalents for the skin, eye lens, blood forming organs, central nervous system, and heart of female astronauts from exposures to the 1977 solar minimum galactic cosmic radiation spectrum for various shielding geometries involving simple spheres and locations within the Space Transportation System (space shuttle) and the International Space Station (ISS) are made using the HZETRN 2010 space radiation transport code. The dose equivalent contributions are broken down by charge groups in order to better understand the sources of the exposures to these organs. For thin shields, contributions from ions heavier than alpha particles comprise at least half of the organ dose equivalent. For thick shields, such as the ISS locations, heavy ions contribute less than 30% and in some cases less than 10% of the organ dose equivalent. Secondary neutron production contributions in thick shields also tend to be as large, or larger, than the heavy ion contributions to the organ dose equivalents.

10 CFR 72.106 - Controlled area of an ISFSI or MRS.

Code of Federal Regulations, 2012 CFR

2012-01-01

... controlled area may not receive from any design basis accident the more limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose...

10 CFR 72.106 - Controlled area of an ISFSI or MRS.

Code of Federal Regulations, 2014 CFR

2014-01-01

... controlled area may not receive from any design basis accident the more limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose...

10 CFR 72.106 - Controlled area of an ISFSI or MRS.

Code of Federal Regulations, 2011 CFR

2011-01-01

... controlled area may not receive from any design basis accident the more limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose...

10 CFR 72.106 - Controlled area of an ISFSI or MRS.

Code of Federal Regulations, 2013 CFR

2013-01-01

... controlled area may not receive from any design basis accident the more limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose...

10 CFR 72.106 - Controlled area of an ISFSI or MRS.

Code of Federal Regulations, 2010 CFR

2010-01-01

... controlled area may not receive from any design basis accident the more limiting of a total effective dose equivalent of 0.05 Sv (5 rem), or the sum of the deep-dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose...

Equivalent Noise Dose Obtained through Hearing Aids in the Classrooms of Hearing-Impaired Children.

ERIC Educational Resources Information Center

Wilde, Ronald A.

1990-01-01

A commercial noise dose meter was used to estimate the equivalent noise dose received through high-gain hearing aids worn in four classrooms in a school for deaf children. There were no significant differences among nominal saturation sound pressure level (SSPL) settings, and all SSPL settings produced very high equivalent noise doses. (Author/JDD)

10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

Code of Federal Regulations, 2014 CFR

2014-01-01

...) a committed effective dose equivalent of 5 rems (stochastic ALI) or (2) a committed dose equivalent of 50 rems to an organ or tissue (non-stochastic ALI). The stochastic ALIs were derived to result in... equivalent to the whole body of 5 rems. The derivation includes multiplying the committed dose equivalent to...

10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

Code of Federal Regulations, 2011 CFR

2011-01-01

...) a committed effective dose equivalent of 5 rems (stochastic ALI) or (2) a committed dose equivalent of 50 rems to an organ or tissue (non-stochastic ALI). The stochastic ALIs were derived to result in... equivalent to the whole body of 5 rems. The derivation includes multiplying the committed dose equivalent to...

10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

Code of Federal Regulations, 2012 CFR

2012-01-01

...) a committed effective dose equivalent of 5 rems (stochastic ALI) or (2) a committed dose equivalent of 50 rems to an organ or tissue (non-stochastic ALI). The stochastic ALIs were derived to result in... equivalent to the whole body of 5 rems. The derivation includes multiplying the committed dose equivalent to...

10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

Code of Federal Regulations, 2010 CFR

2010-01-01

...) a committed effective dose equivalent of 5 rems (stochastic ALI) or (2) a committed dose equivalent of 50 rems to an organ or tissue (non-stochastic ALI). The stochastic ALIs were derived to result in... equivalent to the whole body of 5 rems. The derivation includes multiplying the committed dose equivalent to...

10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

Code of Federal Regulations, 2013 CFR

2013-01-01

...) a committed effective dose equivalent of 5 rems (stochastic ALI) or (2) a committed dose equivalent of 50 rems to an organ or tissue (non-stochastic ALI). The stochastic ALIs were derived to result in... equivalent to the whole body of 5 rems. The derivation includes multiplying the committed dose equivalent to...

ELQ-300 prodrugs for enhanced delivery and single-dose cure of malaria.

PubMed

Miley, Galen P; Pou, Sovitj; Winter, Rolf; Nilsen, Aaron; Li, Yuexin; Kelly, Jane X; Stickles, Allison M; Mather, Michael W; Forquer, Isaac P; Pershing, April M; White, Karen; Shackleford, David; Saunders, Jessica; Chen, Gong; Ting, Li-Min; Kim, Kami; Zakharov, Lev N; Donini, Cristina; Burrows, Jeremy N; Vaidya, Akhil B; Charman, Susan A; Riscoe, Michael K

2015-09-01

ELQ-300 is a preclinical candidate that targets the liver and blood stages of Plasmodium falciparum, as well as the forms that are crucial to transmission of disease: gametocytes, zygotes, and ookinetes. A significant obstacle to the clinical development of ELQ-300 is related to its physicochemical properties. Its relatively poor aqueous solubility and high crystallinity limit absorption to the degree that only low blood concentrations can be achieved following oral dosing. While these low blood concentrations are sufficient for therapy, the levels are too low to establish an acceptable safety margin required by regulatory agencies for clinical development. One way to address the challenging physicochemical properties of ELQ-300 is through the development of prodrugs. Here, we profile ELQ-337, a bioreversible O-linked carbonate ester prodrug of the parent molecule. At the molar equivalent dose of 3 mg/kg of body weight, the delivery of ELQ-300 from ELQ-337 is enhanced by 3- to 4-fold, reaching a maximum concentration of drug in serum (C max) of 5.9 μM by 6 h after oral administration, and unlike ELQ-300 at any dose, ELQ-337 provides single-dose cures of patent malaria infections in mice at low-single-digit milligram per kilogram doses. Our findings show that the prodrug strategy represents a viable approach to overcome the physicochemical limitations of ELQ-300 to deliver the active drug to the bloodstream at concentrations sufficient for safety and toxicology studies, as well as achieving single-dose cures. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Regulating exposure of the lens of the eye to ionising radiations.

PubMed

Thorne, M C

2012-06-01

The International Commission on Radiological Protection (ICRP) has reviewed recent epidemiological evidence suggesting that, for the lens of the eye, the threshold in absorbed dose for the induction of deleterious health effects is about 0.5 Gy. On this basis, the Commission recommends that for occupational exposure in planned exposure situations, the equivalent dose limit for the lens of the eye should be 20 mSv in a year, averaged over defined periods of 5 yr, with exposure not exceeding 50 mSv in any single year. This paper summarises the data that have been taken into account by the ICRP and critically examines whether the proposed downward revision of the dose limit is justified. Overall, it is concluded that the accumulating radiobiological and epidemiological evidence makes it more appropriate to treat cataract induction as a stochastic rather than a deterministic effect. Within this framework, it is illogical to have the same dose limit for the lens of the eye as for the whole body irradiated uniformly. This could be addressed either by removing the special dose limit for the lens of the eye, assigning it an appropriate tissue weighting factor and including it in the computation of the effective dose, or through a composite approach involving the use of a tissue weighting factor for effective dose computations together with a special limit on the equivalent dose to the lens of the eye to ensure that no individual was subject to an unacceptably high risk of induction of clinically significant cataracts.

An analysis of the equivalent dose calculation for the remainder tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zankl, M.; Drexler, G.

1995-09-01

In the 1990 Recommendations of the International Commission on Radiological Protection, the risk-weighted quantity {open_quotes}effective dose equivalent{close_quotes} was replaced by a similar quantity, {open_quotes}effective dose.{close_quotes} Among other alterations, the selection of the organs and tissues contributing to the risk-weighted quantity and their respective weighting factors were changed, including a modified definition of the so-called {open_quotes}remainder.{close_quotes} Close consideration of this latter definition shows that is causes certain ambiguities are unexpected effects which are dealt with in the following. For several geometries of external photon irradiation, the numerical differences of two possible methods of evaluating the remainder dose from the doses tomore » ten single organs, namely as arithmetic mean or as mass weighted average, are assessed. It is shown that deviation from these averaging procedures, as prescribed for these cases where a remainder organ receives a higher dose than an organ with a specified weighting factor, cause discontinuities in the energy dependence of the remainder dose and, consequently, also non-additivity of this quantity. These problems are discussed, and it is shown that, although the numerical consequences for the calculation of the effective dose are small, this unsatisfactory situation needs clarification. One approach might be to abolish some of the ICRP guidance relating to the appropriate tissue weighting factors for the remainder tissues and organs and to make other guidance more precise. 14 refs., 12 figs., 2 tabs.« less

Bioequivalence of budesonide plus formoterol (BF) Spiromax® and BF Turbohaler® (with and without charcoal block) in healthy volunteers.

PubMed

Weisfeld, Lori; Shu, Youyi; Shah, Tushar P

2015-07-01

Budesonide formoterol (BF) Spiromax® is a breath-actuated dry-powder inhaler designed to deliver similar combinations of budesonide and formoterol as Symbicort® Turbohaler®. We performed two studies to demonstrate pharmacokinetic (PK) equivalence of BF Spiromax with BF Turbohaler. Two single-center, open-label, randomized, 5-period crossover studies were performed. The first study compared BF Spiromax 160/4.5 μg with BF Turbohaler 200/6 μg, while the second study compared BF Spiromax 320/9 μg with BF Turbohaler 400/12 μg. All treatments were administered with and without charcoal. PK parameters were calculated by measuring plasma drug concentrations from blood samples taken pre-dose and up to 24 hours post-dose. In each study, 90 healthy volunteers were randomized. Bioequivalence of BF Spiromax with BF Turbohaler was demonstrated for budesonide and formoterol (AUC0-t and Cmax (90% confidence intervals of the geometric mean between-device ratios for both parameters were within the predefined range of 0.80-1.25 in both studies)). Equivalence was observed without use of charcoal (overall absorption post-inhalation) and with charcoal (pulmonary absorption). There were no major differences between treatments in tmax for either budesonide or formoterol. All study treatments were well tolerated (one treatment-emergent adverse event (TEAE) in the medium-dose study and four TEAEs in the high-dose study). These studies indicate that BF Spiromax (±charcoal block) is bioequivalent to BF Turbohaler with respect to the PK parameters assessed. Single doses of BF Spiromax were well tolerated; the overall safety profile of BF Spiromax and BF Turbohaler was similar.

Motion-robust intensity-modulated proton therapy for distal esophageal cancer.

PubMed

Yu, Jen; Zhang, Xiaodong; Liao, Li; Li, Heng; Zhu, Ronald; Park, Peter C; Sahoo, Narayan; Gillin, Michael; Li, Yupeng; Chang, Joe Y; Komaki, Ritsuko; Lin, Steven H

2016-03-01

To develop methods for evaluation and mitigation of dosimetric impact due to respiratory and diaphragmatic motion during free breathing in treatment of distal esophageal cancers using intensity-modulated proton therapy (IMPT). This was a retrospective study on 11 patients with distal esophageal cancer. For each patient, four-dimensional computed tomography (4D CT) data were acquired, and a nominal dose was calculated on the average phase of the 4D CT. The changes of water equivalent thickness (ΔWET) to cover the treatment volume from the peak of inspiration to the valley of expiration were calculated for a full range of beam angle rotation. Two IMPT plans were calculated: one at beam angles corresponding to small ΔWET and one at beam angles corresponding to large ΔWET. Four patients were selected for the calculation of 4D-robustness-optimized IMPT plans due to large motion-induced dose errors generated in conventional IMPT. To quantitatively evaluate motion-induced dose deviation, the authors calculated the lowest dose received by 95% (D95) of the internal clinical target volume for the nominal dose, the D95 calculated on the maximum inhale and exhale phases of 4D CT DCT0 andDCT50 , the 4D composite dose, and the 4D dynamic dose for a single fraction. The dose deviation increased with the average ΔWET of the implemented beams, ΔWETave. When ΔWETave was less than 5 mm, the dose error was less than 1 cobalt gray equivalent based on DCT0 and DCT50 . The dose deviation determined on the basis of DCT0 and DCT50 was proportionally larger than that determined on the basis of the 4D composite dose. The 4D-robustness-optimized IMPT plans notably reduced the overall dose deviation of multiple fractions and the dose deviation caused by the interplay effect in a single fraction. In IMPT for distal esophageal cancer, ΔWET analysis can be used to select the beam angles that are least affected by respiratory and diaphragmatic motion. To further reduce dose deviation, the 4D-robustness optimization can be implemented for IMPT planning. Calculation of DCT0 and DCT50 is a conservative method to estimate the motion-induced dose errors.

Simulated response of a multi-element thick gas electron multiplier-based microdosimeter to high energy neutrons.

PubMed

Moslehi, Amir; Raisali, Gholamreza

2018-07-01

The response of a microdosimeter for neutrons above 14 MeV is investigated. The mean quality factors and dose-equivalents are determined using lineal energy distributions calculated by Monte Carlo simulations (Geant4 toolkit). From 14 MeV to 5 GeV, the mean quality factors were found to vary between 6.00 and 9.30 and the dose-equivalents were in agreement with the true ambient dose-equivalent at the depth of 10 mm inside the ICRU sphere, H * (10). An energy-independent dose-equivalent response around a median value of 0.86 within 22% uncertainty was obtained. Therefore, the microdosimeter is appropriate for dose-equivalent measurement of high-energy neutrons. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biphasic and monophasic repair: comparative implications for biologically equivalent dose calculations in pulsed dose rate brachytherapy of cervical carcinoma

PubMed Central

Millar, W T; Davidson, S E

2013-01-01

Objective: To consider the implications of the use of biphasic rather than monophasic repair in calculations of biologically-equivalent doses for pulsed-dose-rate brachytherapy of cervix carcinoma. Methods: Calculations are presented of pulsed-dose-rate (PDR) doses equivalent to former low-dose-rate (LDR) doses, using biphasic vs monophasic repair kinetics, both for cervical carcinoma and for the organ at risk (OAR), namely the rectum. The linear-quadratic modelling calculations included effects due to varying the dose per PDR cycle, the dose reduction factor for the OAR compared with Point A, the repair kinetics and the source strength. Results: When using the recommended 1 Gy per hourly PDR cycle, different LDR-equivalent PDR rectal doses were calculated depending on the choice of monophasic or biphasic repair kinetics pertaining to the rodent central nervous and skin systems. These differences virtually disappeared when the dose per hourly cycle was increased to 1.7 Gy. This made the LDR-equivalent PDR doses more robust and independent of the choice of repair kinetics and α/β ratios as a consequence of the described concept of extended equivalence. Conclusion: The use of biphasic and monophasic repair kinetics for optimised modelling of the effects on the OAR in PDR brachytherapy suggests that an optimised PDR protocol with the dose per hourly cycle nearest to 1.7 Gy could be used. Hence, the durations of the new PDR treatments would be similar to those of the former LDR treatments and not longer as currently prescribed. Advances in knowledge: Modelling calculations indicate that equivalent PDR protocols can be developed which are less dependent on the different α/β ratios and monophasic/biphasic kinetics usually attributed to normal and tumour tissues for treatment of cervical carcinoma. PMID:23934965

Combined analysis of three crossover clinical pharmacology studies of effects of rabeprazole and esomeprazole on 24-h intragastric pH in healthy volunteers.

PubMed

Norris, V; Baisley, K; Dunn, K; Warrington, S; Morocutti, A

2007-02-15

To compare antisecretory effects of rabeprazole and esomeprazole after single and repeat dosing in Helicobacter pylori-negative healthy volunteers. Results were pooled from three smaller, open, crossover, randomized studies to obtain data from 80 subjects. The studies compared: (a) 5 days' dosing of 20 mg rabeprazole and esomeprazole (n = 24); (b) single doses of rabeprazole 20 mg and esomeprazole 40 mg (n = 27) and (c) 5 days' dosing of rabeprazole 10 mg and esomeprazole 20 mg (n = 29). Washout periods were > or =14 days. Intragastric pH was recorded continuously for 24 h on days 0, 1 and 5. Single doses of rabeprazole 20 mg maintained 24-h intragastric pH >4 for longer than esomeprazole 20 mg (45% vs. 32%; P < 0.001); rabeprazole 20 mg and esomeprazole 40 mg were equivalent in their effects. After 5 days' dosing, rabeprazole 20 mg maintained pH >4 for longer than esomeprazole 20 mg (62% vs. 56%; P = 0.046); the reverse was true for esomeprazole 20 mg vs. rabeprazole 10 mg (56% vs. 48%; P = 0.035). In general, intragastric pH AUC during 0-5 h after dosing was higher after esomeprazole than rabeprazole, whereas the reverse was true during the night. The order of effects on 24-h pH was: rabeprazole 10 mg < or = esomeprazole 20 mg < rabeprazole 20 mg = esomeprazole 40 mg. Esomeprazole acts faster, whereas rabeprazole's effect lasts longer.

Pharmacokinetics and Bioequivalence Evaluation of 2 Loxoprofen Tablets in Healthy Egyptian Male Volunteers.

PubMed

Helmy, Sally A

2013-04-01

The objective of this study was to assess the in vitro dissolution and to evaluate the bioavailability of two brands of Loxoprofen sodium dihydrate tablets. Loxoprofen tablets (68.1 mg loxoprofen sodium dihydrate equivalent to 60 mg loxoprofen; test) relative to Roxonin tablets (68.1 mg loxoprofen sodium dihydrate equivalent to 60 mg loxoprofen; reference). In vitro study was adopted to determine and compare the dissolution behavior of both products. In vivo study was conducted according to a single-center, randomized, single-dose, and laboratory-blinded, 2-period, 2-sequence, crossover design with a washout period of 1 week. Under fasting conditions, 24 healthy Egyptian adult male volunteers were randomly allocated to receive a single dose of either test or reference product. Blood samples were collected at specified time intervals, and plasma was analyzed for loxoprofen concentrations using a validated high-performance liquid chromatography assay method. The pharmacokinetic parameters Cmax , AUC0-t , AUC0-∞ , tmax , and t1/2 were determined from plasma concentration-time profiles. The 90% confidence intervals for the ratio Cmax , AUC0-t , and AUCt-∞ of the test product over those of reference were within the acceptable range (0.8-1.25) for bioequivalence. On the basis of these results, the two-loxoprofen formulations are considered bioequivalent. © The Author(s) 2013.

RCT: Module 2.06, Air Sampling Program and Methods, Course 8772

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hillmer, Kurt T.

The inhalation of radioactive particles is the largest cause of an internal radiation dose. Airborne radioactivity measurements are necessary to ensure that the control measures are and continue to be effective. Regulations govern the allowable effective dose equivalent to an individual. The effective dose equivalent is determined by combining the external and internal dose equivalent values. Typically, airborne radioactivity levels are maintained well below allowable levels to keep the total effective dose equivalent small. This course will prepare the student with the skills necessary for RCT qualification by passing quizzes, tests, and the RCT Comprehensive Phase 1, Unit 2 Examinationmore » (TEST 27566) and will provide in-the-field skills.« less

Passive dosimetry aboard the Mir Orbital Station: internal measurements.

PubMed

Benton, E R; Benton, E V; Frank, A L

2002-10-01

Passive radiation dosimeters were exposed aboard the Mir Orbital Station over a substantial portion of the solar cycle in order to measure the change in dose and dose equivalent rates as a function of time. During solar minimum, simultaneous measurements of the radiation environment throughout the habitable volume of the Mir were made using passive dosimeters in order to investigate the effect of localized shielding on dose and dose equivalent. The passive dosimeters consisted of a combination of thermoluminescent detectors to measure absorbed dose and CR-39 PNTDs to measure the linear energy transfer (LET) spectrum from charged particles of LET infinity H2O > or = 5 keV/micrometers. Results from the two detector types were then combined to yield mean total dose rate, mean dose equivalent rate, and average quality factor. Contrary to expectations, both dose and dose equivalent rates measured during May-October 1991 near solar maximum were higher than similar measurements carried out in 1996-1997 during solar minimum. The elevated dose and dose equivalent rates measured in 1991 were probably due to a combination of intense solar activity, including a large solar particle event on 9 June 1991, and the temporary trapped radiation belt created in the slot region by the solar particle event and ensuing magnetic storm of 24 March 1991. During solar minimum, mean dose and dose equivalent rates were found to vary by factors of 1.55 and 1.37, respectively, between different locations through the interior of Mir. More heavily shielded locations tended to yield lower total dose and dose equivalent rates, but higher average quality factor than did more lightly shielding locations. However, other factors such as changes in the immediate shielding environment surrounding a given detector location, changes in the orientation of the Mir relative to its velocity vector, and changes in the altitude of the station also contributed to the variation. Proton and neutron-induced target fragment secondaries, not primary galactic cosmic rays, were found to dominate the LET spectrum above 100 keV/micrometers. This indicates that in low earth orbit, trapped protons in the South Atlantic Anomaly are responsible for the major fraction of the total dose equivalent. c2002 Elsevier Science Ltd. All rights reserved.

Pharmacokinetic Studies in Healthy Subjects for the Development of an Extended-Release Tablet Formulation of Guaifenesin: A 505(b)(2) New Drug Application Approval.

PubMed

Vilson, Lineau; Owen, Joel S

2013-01-01

Guaifenesin is an expectorant used to improve mucociliary clearance (MCC) and relieve chest congestion from upper respiratory tract infections. Immediate-release (IR) guaifenesin requires dosing every 4 hours to maintain efficacy because of the drug's short half-life. Extended-release (ER) guaifenesin has been developed to prolong efficacy and reduce dosing frequency. As part of the 505(b)(2) new drug application (NDA), the pharmacokinetics (PK) of an ER bi-layer tablet formulation of guaifenesin (Mucinex®) and bioequivalence to an over-the-counter (OTC) monograph IR formulation were evaluated in healthy subjects. In one study, subjects received 1,200 mg ER guaifenesin every 12 hours or 400 mg IR guaifenesin every 4 hours for 6 days. Steady-state exposures were equivalent between the two products, as demonstrated by AUC and Cmax . In another study, subjects received a single dose of 600 mg (fasted) or 1,200 mg (fasted or fed) ER bi-layer tablet formulations. AUC and Cmax were equivalent between both states for the 1,200 mg ER dose. However, Tmax of 1,200 mg ER guaifenesin was later in the fed than the fasted state. ER guaifenesin is bioequivalent to corresponding OTC monograph doses of IR guaifenesin. ER guaifenesin offers a convenient 12-hour dosing alternative to 4-hour dosing of IR guaifenesin. © The Author(s) 2013.

Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model.

PubMed

Couto, José Guilherme; Bravo, Isabel; Pirraco, Rui

2011-09-01

The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009. In the first phase we studied the influence of the pulse dose and the pulse time in the biological equivalence between LDR and PDR treatments using the Linear Quadratic Model (LQM). In the second phase, the equivalent dose in 2 Gy/fraction (EQD(2)) for the tumor, rectum and bladder in treatments performed with both techniques was evaluated and statistically compared. All evaluated patients had stage IIB cervical cancer and were treated with External Beam Radiotherapy (EBRT) plus two Brachytherapy (BT) applications. Data were collected from 48 patients (26 patients treated with LDR and 22 patients with PDR). In the analyses of the influence of PDR parameters in the biological equivalence between LDR and PDR treatments (Phase 1), it was calculated that if the pulse dose in PDR was kept equal to the LDR dose rate, a small the-rapeutic loss was expected. If the pulse dose was decreased, the therapeutic window became larger, but a correction in the prescribed dose was necessary. In PDR schemes with 1 hour interval between pulses, the pulse time did not influence significantly the equivalent dose. In the comparison between the groups treated with LDR and PDR (Phase 2) we concluded that they were not equivalent, because in the PDR group the total EQD(2) for the tumor, rectum and bladder was smaller than in the LDR group; the LQM estimated that a correction in the prescribed dose of 6% to 10% was ne-cessary to avoid therapeutic loss. A correction in the prescribed dose was necessary; this correction should be achieved by calculating the PDR dose equivalent to the desired LDR total dose.

Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model

PubMed Central

Bravo, Isabel; Pirraco, Rui

2011-01-01

Purpose The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009. Material and methods In the first phase we studied the influence of the pulse dose and the pulse time in the biological equivalence between LDR and PDR treatments using the Linear Quadratic Model (LQM). In the second phase, the equivalent dose in 2 Gy/fraction (EQD2) for the tumor, rectum and bladder in treatments performed with both techniques was evaluated and statistically compared. All evaluated patients had stage IIB cervical cancer and were treated with External Beam Radiotherapy (EBRT) plus two Brachytherapy (BT) applications. Data were collected from 48 patients (26 patients treated with LDR and 22 patients with PDR). Results In the analyses of the influence of PDR parameters in the biological equivalence between LDR and PDR treatments (Phase 1), it was calculated that if the pulse dose in PDR was kept equal to the LDR dose rate, a small the-rapeutic loss was expected. If the pulse dose was decreased, the therapeutic window became larger, but a correction in the prescribed dose was necessary. In PDR schemes with 1 hour interval between pulses, the pulse time did not influence significantly the equivalent dose. In the comparison between the groups treated with LDR and PDR (Phase 2) we concluded that they were not equivalent, because in the PDR group the total EQD2 for the tumor, rectum and bladder was smaller than in the LDR group; the LQM estimated that a correction in the prescribed dose of 6% to 10% was ne-cessary to avoid therapeutic loss. Conclusions A correction in the prescribed dose was necessary; this correction should be achieved by calculating the PDR dose equivalent to the desired LDR total dose. PMID:23346123

Bioequivalence of a fixed-dose repaglinide/metformin combination tablet and equivalent doses of repaglinide and metformin tablets
.

PubMed

Cho, Hea-Young; Ngo, Lien; Kim, Sang-Ki; Choi, Yoonho; Lee, Yong-Bok

2018-06-01

This study was conducted to determine whether a fixed-dose combination (FDC) tablet of repaglinide/metformin (2/500 mg) is equivalent to coadministration of equivalent doses of individual (EDI) tablets of repaglinide (2 mg) and metformin (500 mg) in healthy Korean male subjects. This study was conducted as an open-label, randomized, single-dose, two-period, two-sequence crossover design in 50 healthy Korean male subjects who received an FDC tablet or EDI tablets. Plasma concentrations of repaglinide and metformin were determined for up to 24 hours using a validated UPLC-MS/MS method. Bioequivalence was assessed according to current guidelines issued by the U.S. Food and Drug Administration (FDA) and Korean legislation. Tolerability was also evaluated throughout the study via subject interview, vital signs, and blood sampling. Point estimates (90% CIs) for AUC_0-t, AUC_0-∞, and C_max based on EDI tablets were 110.07 (102.25 - 118.49), 109.90 (101.70 - 118.39), and 112.60 (101.49 - 124.85), respectively, for repaglinide. They were 95.18 (89.62 - 101.05), 95.00 (89.74 - 100.65), and 98.44 (92.72 - 104.50), respectively, for metformin. These results satisfied the bioequivalence criteria of 80.00 - 125.00% proposed by the FDA and Korean legislation. Results of pharmacokinetic analysis suggested that repaglinide and metformin in FDC tablets were bioequivalent to EDI tablets of repaglinide (2 mg) and metformin (500 mg) in healthy Korean male subjects. Both formulations appeared to be well tolerated.
.

A systematic review of palliative bone radiotherapy based on pain relief and retreatment rates.

PubMed

Pin, Yvan; Paix, Adrien; Le Fèvre, Clara; Antoni, Delphine; Blondet, Cyrille; Noël, Georges

2018-03-01

Palliative radiotherapy has been shown to have effects on Quality of Life during painful bone metastasis. This review aimed to determine equivalence in pain relief (PR) and retreatment rate (RR) using both single and multi-fraction irradiations, based on evaluation of the trial's quality. We performed a systematic review since ICRU 50 Report (1993) to June 2017, then evaluated trials for reproducibility and good methodology criteria. We found five studies that were reproducible in both dose and volume prescription. One study used three-dimensional (3D) treatment planning. Equivalence between single and multi-fraction schedules was demonstrated for PR after 3 months, but a 2-3 time RR appeared after single-fraction schedules, notably in the first year after treatment (primarily during the first four months). Reserving long course therapy for well-preserved patients would allow for better long-term efficacy with lower RR, while altered patients would suffer less from single-fraction treatments. It appears that life expectancy might not be used as a criterion for this choice. Copyright © 2018 Elsevier B.V. All rights reserved.

Identifying a maximum tolerated contour in two-dimensional dose-finding

PubMed Central

Wages, Nolan A.

2016-01-01

The majority of Phase I methods for multi-agent trials have focused on identifying a single maximum tolerated dose combination (MTDC) among those being investigated. Some published methods in the area have been based on the notion that there is no unique MTDC, and that the set of dose combinations with acceptable toxicity forms an equivalence contour in two dimensions. Therefore, it may be of interest to find multiple MTDC's for further testing for efficacy in a Phase II setting. In this paper, we present a new dose-finding method that extends the continual reassessment method to account for the location of multiple MTDC's. Operating characteristics are demonstrated through simulation studies, and are compared to existing methodology. Some brief discussion of implementation and available software is also provided. PMID:26910586

Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carl, W. F.

NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

Comparison of adult and child radiation equivalent doses from 2 dental cone-beam computed tomography units.

PubMed

Al Najjar, Anas; Colosi, Dan; Dauer, Lawrence T; Prins, Robert; Patchell, Gayle; Branets, Iryna; Goren, Arthur D; Faber, Richard D

2013-06-01

With the advent of cone-beam computed tomography (CBCT) scans, there has been a transition toward these scans' replacing traditional radiographs for orthodontic diagnosis and treatment planning. Children represent a significant proportion of orthodontic patients. Similar CBCT exposure settings are predicted to result in higher equivalent doses to the head and neck organs in children than in adults. The purpose of this study was to measure the difference in equivalent organ doses from different scanners under similar settings in children compared with adults. Two phantom heads were used, representing a 33-year-old woman and a 5-year-old boy. Optically stimulated dosimeters were placed at 8 key head and neck organs, and equivalent doses to these organs were calculated after scanning. The manufacturers' predefined exposure settings were used. One scanner had a pediatric preset option; the other did not. Scanning the child's phantom head with the adult settings resulted in significantly higher equivalent radiation doses to children compared with adults, ranging from a 117% average ratio of equivalent dose to 341%. Readings at the cervical spine level were decreased significantly, down to 30% of the adult equivalent dose. When the pediatric preset was used for the scans, there was a decrease in the ratio of equivalent dose to the child mandible and thyroid. CBCT scans with adult settings on both phantom heads resulted in higher radiation doses to the head and neck organs in the child compared with the adult. In practice, this might result in excessive radiation to children scanned with default adult settings. Collimation should be used when possible to reduce the radiation dose to the patient. While CBCT scans offer a valuable tool, use of CBCT scans should be justified on a specific case-by-case basis. Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Absorbed Dose and Dose Equivalent Calculations for Modeling Effective Dose

NASA Technical Reports Server (NTRS)

Welton, Andrew; Lee, Kerry

2010-01-01

While in orbit, Astronauts are exposed to a much higher dose of ionizing radiation than when on the ground. It is important to model how shielding designs on spacecraft reduce radiation effective dose pre-flight, and determine whether or not a danger to humans is presented. However, in order to calculate effective dose, dose equivalent calculations are needed. Dose equivalent takes into account an absorbed dose of radiation and the biological effectiveness of ionizing radiation. This is important in preventing long-term, stochastic radiation effects in humans spending time in space. Monte carlo simulations run with the particle transport code FLUKA, give absorbed and equivalent dose data for relevant shielding. The shielding geometry used in the dose calculations is a layered slab design, consisting of aluminum, polyethylene, and water. Water is used to simulate the soft tissues that compose the human body. The results obtained will provide information on how the shielding performs with many thicknesses of each material in the slab. This allows them to be directly applicable to modern spacecraft shielding geometries.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perko, Z; Bortfeld, T; Hong, T

Purpose: The safe use of radiotherapy requires the knowledge of tolerable organ doses. For experimental fractionation schemes (e.g. hypofractionation) these are typically extrapolated from traditional fractionation schedules using the Biologically Effective Dose (BED) model. This work demonstrates that using the mean dose in the standard BED equation may overestimate tolerances, potentially leading to unsafe treatments. Instead, extrapolation of mean dose tolerances should take the spatial dose distribution into account. Methods: A formula has been derived to extrapolate mean physical dose constraints such that they are mean BED equivalent. This formula constitutes a modified BED equation where the influence of themore » spatial dose distribution is summarized in a single parameter, the dose shape factor. To quantify effects we analyzed 14 liver cancer patients previously treated with proton therapy in 5 or 15 fractions, for whom also photon IMRT plans were available. Results: Our work has two main implications. First, in typical clinical plans the dose distribution can have significant effects. When mean dose tolerances are extrapolated from standard fractionation towards hypofractionation they can be overestimated by 10–15%. Second, the shape difference between photon and proton dose distributions can cause 30–40% differences in mean physical dose for plans having the same mean BED. The combined effect when extrapolating proton doses to mean BED equivalent photon doses in traditional 35 fraction regimens resulted in up to 7–8 Gy higher doses than when applying the standard BED formula. This can potentially lead to unsafe treatments (in 1 of the 14 analyzed plans the liver mean dose was above its 32 Gy tolerance). Conclusion: The shape effect should be accounted for to avoid unsafe overestimation of mean dose tolerances, particularly when estimating constraints for hypofractionated regimens. In addition, tolerances established for a given treatment modality cannot necessarily be applied to other modalities with drastically different dose distributions.« less

Multiple anatomy optimization of accumulated dose

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, W. Tyler, E-mail: watkinswt@virginia.edu; Siebers, Jeffrey V.; Moore, Joseph A.

Purpose: To investigate the potential advantages of multiple anatomy optimization (MAO) for lung cancer radiation therapy compared to the internal target volume (ITV) approach. Methods: MAO aims to optimize a single fluence to be delivered under free-breathing conditions such that the accumulated dose meets the plan objectives, where accumulated dose is defined as the sum of deformably mapped doses computed on each phase of a single four dimensional computed tomography (4DCT) dataset. Phantom and patient simulation studies were carried out to investigate potential advantages of MAO compared to ITV planning. Through simulated delivery of the ITV- and MAO-plans, target dosemore » variations were also investigated. Results: By optimizing the accumulated dose, MAO shows the potential to ensure dose to the moving target meets plan objectives while simultaneously reducing dose to organs at risk (OARs) compared with ITV planning. While consistently superior to the ITV approach, MAO resulted in equivalent OAR dosimetry at planning objective dose levels to within 2% volume in 14/30 plans and to within 3% volume in 19/30 plans for each lung V20, esophagus V25, and heart V30. Despite large variations in per-fraction respiratory phase weights in simulated deliveries at high dose rates (e.g., treating 4/10 phases during single fraction beams) the cumulative clinical target volume (CTV) dose after 30 fractions and per-fraction dose were constant independent of planning technique. In one case considered, however, per-phase CTV dose varied from 74% to 117% of prescription implying the level of ITV-dose heterogeneity may not be appropriate with conventional, free-breathing delivery. Conclusions: MAO incorporates 4DCT information in an optimized dose distribution and can achieve a superior plan in terms of accumulated dose to the moving target and OAR sparing compared to ITV-plans. An appropriate level of dose heterogeneity in MAO plans must be further investigated.« less

Space Radiation Organ Doses for Astronauts on Past and Future Missions

NASA Technical Reports Server (NTRS)

Cucinotta, Francis A.

2007-01-01

We review methods and data used for determining astronaut organ dose equivalents on past space missions including Apollo, Skylab, Space Shuttle, NASA-Mir, and International Space Station (ISS). Expectations for future lunar missions are also described. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra, or a related quantity, the lineal energy (y) spectra that is measured by a tissue equivalent proportional counter (TEPC). These data are used in conjunction with space radiation transport models to project organ specific doses used in cancer and other risk projection models. Biodosimetry data from Mir, STS, and ISS missions provide an alternative estimate of organ dose equivalents based on chromosome aberrations. The physical environments inside spacecraft are currently well understood with errors in organ dose projections estimated as less than plus or minus 15%, however understanding the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons for which there are no human data to estimate risks. The accuracy of projections of organ dose equivalents described here must be supplemented with research on the health risks of space exposure to properly assess crew safety for exploration missions.

Fast, epithermal and thermal photoneutron dosimetry in air and in tissue equivalent phantom for a high-energy X-ray medical accelerator.

PubMed

Sohrabi, Mehdi; Hakimi, Amir

2018-02-01

Photoneutron (PN) dosimetry in fast, epithermal and thermal energy ranges originated from the beam and albedo neutrons in high-energy X-ray medical accelerators is highly important from scientific, technical, radiation protection and medical physics points of view. Detailed dose equivalents in the fast, epithermal and thermal PN energy ranges in air up to 2m as well as at 35 positions from the central axis of 12 cross sections of the phantom at different depths were determined in 18MV X-ray beams of a Siemens ONCOR accelerator. A novel dosimetry method based on polycarbonate track dosimeters (PCTD)/ 10 B (with/without cadmium cover) was used to determine and separate different PN dose equivalents in air and in a multilayer polyethylene phantom. Dose equivalent distributions of PNs, as originated from the main beam and/or albedo PNs, on cross-plane, in-plane and diagonal axes in 10cm×10cm fields are reported. PN dose equivalent distributions on the 3 axes have their maxima at the isocenter. Epithermal and thermal PN depth dose equivalent distributions in the phantom for different positions studied peak at ∼3cm depth. The neutron dosimeters used for the first time in such studies are highly effective for separating dose equivalents of PNs in the studied energy ranges (beam and/or albedo). The PN dose equivalent data matrix made available in this paper is highly essential for detailed patient dosimetry in general and for estimating secondary cancer risks in particular. Copyright © 2017. Published by Elsevier GmbH.

Calculation of Radiation Protection Quantities and Analysis of Astronaut Orientation Dependence

NASA Technical Reports Server (NTRS)

Clowdsley, Martha S.; Nealy, John E.; Atwell, William; Anderson, Brooke M.; Luetke, Nathan J.; Wilson, John W.

2006-01-01

Health risk to astronauts due to exposure to ionizing radiation is a primary concern for exploration missions and may become the limiting factor for long duration missions. Methodologies for evaluating this risk in terms of radiation protection quantities such as dose, dose equivalent, gray equivalent, and effective dose are described. Environment models (galactic cosmic ray and solar particle event), vehicle/habitat geometry models, human geometry models, and transport codes are discussed and sample calculations for possible lunar and Mars missions are used as demonstrations. The dependence of astronaut health risk, in terms of dosimetric quantities, on astronaut orientation within a habitat is also examined. Previous work using a space station type module exposed to a proton spectrum modeling the October 1989 solar particle event showed that reorienting the astronaut within the module could change the calculated dose equivalent by a factor of two or more. Here the dose equivalent to various body tissues and the whole body effective dose due to both galactic cosmic rays and a solar particle event are calculated for a male astronaut in two different orientations, vertical and horizontal, in a representative lunar habitat. These calculations also show that the dose equivalent at some body locations resulting from a solar particle event can vary by a factor of two or more, but that the dose equivalent due to galactic cosmic rays has a much smaller (<15%) dependence on astronaut orientation.

[Nephrotoxicity of Aristolochia manshuriensis and aristolochic acids in mice].

PubMed

Ding, Xiao-shuang; Liang, Ai-hua; Wang, Jin-hua; Xiao, Yong-qing; Wu, Zi-lun; Li, Chun-ying; Li, Li; He, Rong; Hui, Lian-qiang; Liu, Bao-yan

2005-07-01

The acute toxic effects of Aristolochia manshuriensis (GMT) and the total aristolochic acids (TA) were compared in mice with aristolochic acid A (AA) as the dose standard. The dose relationship of the renal toxicity induced by Aristolochia manshuriensis was determined. A single dose of GMT extract or TA was given intragastrically to mice at different doses. LD50 values, the blood levels of BUN, Cr and ALT were measured. A histomorphological study was also performed in livers and kidneys of mice. LD50 value of GMT extract was 4.4 g x kg(-1) which was equivalent to 40 mg x kg(-1) as calculated by the content of AA in GMT extract, and this value was comparable with LD50 obtained from TA given intragastrically in mice (equivalent to 33 mg x kg(-1) of AA for male and 37 mg x kg(-1) for female). GMT extract caused a significant increase in blood BUN and Cr and an obvious morphological change in kidney in a dose-dependent manner at doses of AA 4.5 mg x kg(-1) and above. Liver damage, characterized by both an increase in blood level of AST and histomorphological change, was observed at doses of AA 25 mg x kg(-1) and above. All changes were in proportion to the doses of AA. GMT causes both renal and liver toxicity. The dose leading to nephrotoxicity is much lower than that inducing hepatatoxicity. Aristolochic acids existed in GMT are the main toxic components to cause renal toxicity which is a crucial cause to result in death. The lethality and nephrotoxicity of GMT is in proportion to the doses of AA.

Effective dose equivalent on the ninth Shuttle--Mir mission (STS-91)

NASA Technical Reports Server (NTRS)

Yasuda, H.; Badhwar, G. D.; Komiyama, T.; Fujitaka, K.

2000-01-01

Organ and tissue doses and effective dose equivalent were measured using a life-size human phantom on the ninth Shuttle-Mir Mission (STS-91, June 1998), a 9.8-day spaceflight at low-Earth orbit (about 400 km in altitude and 51.65 degrees in inclination). The doses were measured at 59 positions using a combination of thermoluminescent dosimeters of Mg(2)SiO(4):Tb (TDMS) and plastic nuclear track detectors (PNTD). In correcting the change in efficiency of the TDMS, it was assumed that reduction of efficiency is attributed predominantly to HZE particles with energy greater than 100 MeV nucleon(-1). A conservative calibration curve was chosen for determining LET from the PNTD track-formation sensitivities. The organ and tissue absorbed doses during the mission ranged from 1.7 to 2.7 mGy and varied by a factor of 1.6. The dose equivalent ranged from 3.4 to 5.2 mSv and varied by a factor of 1.5 on the basis of the dependence of Q on LET in the 1990 recommendations of the ICRP. The effective quality factor (Q(e)) varied from 1.7 to 2.4. The dose equivalents for several radiation-sensitive organs, such as the stomach, lung, gonad and breast, were not significantly different from the skin dose equivalent (H(skin)). The effective dose equivalent was evaluated as 4.1 mSv, which was about 90% of the H(skin).

Relative Impact of Incorporating Pharmacokinetics on ...

EPA Pesticide Factsheets

The use of high-throughput in vitro assays has been proposed to play a significant role in the future of toxicity testing. In this study, rat hepatic metabolic clearance and plasma protein binding were measured for 59 ToxCast phase I chemicals. Computational in vitro-to-in vivo extrapolation was used to estimate the daily dose in a rat, called the oral equivalent dose, which would result in steady-state in vivo blood concentrations equivalent to the AC50 or lowest effective concentration (LEC) across more than 600 ToxCast phase I in vitro assays. Statistical classification analysis was performed using either oral equivalent doses or unadjusted AC50/LEC values for the in vitro assays to predict the in vivo effects of the 59 chemicals. Adjusting the in vitro assays for pharmacokinetics did not improve the ability to predict in vivo effects as either a discrete (yes or no) response or a low effect level (LEL) on a continuous dose scale. Interestingly, a comparison of the in vitro assay with the lowest oral equivalent dose with the in vivo endpoint with the lowest LEL suggested that the lowest oral equivalent dose may provide a conservative estimate of the point of departure for a chemical in a dose-response assessment. Furthermore, comparing the oral equivalent doses for the in vitro assays with the in vivo dose range that resulted in adverse effects identified more coincident in vitro assays across chemicals than expected by chance, suggesting that the approach ma

Quality factor and dose equivalent investigations aboard the Soviet Space Station Mir

NASA Astrophysics Data System (ADS)

Bouisset, P.; Nguyen, V. D.; Parmentier, N.; Akatov, Ia. A.; Arkhangel'Skii, V. V.; Vorozhtsov, A. S.; Petrov, V. M.; Kovalev, E. E.; Siegrist, M.

1992-07-01

Since Dec 1988, date of the French-Soviet joint space mission 'ARAGATZ', the CIRCE device, had recorded dose equivalent and quality factor values inside the Mir station (380-410 km, 51.5 deg). After the initial gas filling two years ago, the low pressure tissue equivalent proportional counter is still in good working conditions. Some results of three periods are presented. The average dose equivalent rates measured are respectively 0.6, 0.8 and 0.6 mSv/day with a quality factor equal to 1.9. Some detailed measurements show the increasing of the dose equivalent rates through the SAA and near polar horns. The real time determination of the quality factors allows to point out high linear energy transfer events with quality factors in the range 10-20.

Qianliguang (Senecio scandens) safety dilemma: dose is the key?

PubMed

Lin, Ge; Li, Song-Lin; Li, Mi; Li, Na; Sun-Kin Chan, Sunny; Chan, Wood-Yee; Zhao, Zhong-Zhen

2009-08-01

Qianliguang ( SENECIO SCANDENS) is a common Chinese medicinal herb. Qianliguang-containing herbal proprietary products are registered as over-the-counter remedies in China and exported to Western countries. The safety of using Qianliguang and its products has raised general concerns because of a potential risk of the presence of hepatotoxic pyrrolizidine alkaloids (PAs). A systematic toxicological study is thus required to verify this public concern. In the present article, we report, for the first time, that S. SCANDENS contains nine hepatotoxic PAs with a content of 6.95-7.19 microg/g. At a dose equivalent to the daily intake recommended by the Pharmacopoeia of China, the total content of toxic PAs in Qianliguang was determined to be 3.48 microg/kg/day, which is far below the lowest dose to cause hepatotoxicity (15 microg/kg/day) suggested by the International Program on Chemical Safety. No significant hepatotoxic effects were observed in rats fed with the extract at this human-equivalent dose for 14 consecutive days. However, a single overdose of the herbal water extract (6 g/kg), which was about 8-fold higher than the recommended dose, produced typical PA-induced hepatotoxicity in rats. Therefore, appropriate dosage guidelines should be implemented for the herbal industry, for export/import retailers, and for herbal medicine practitioners to ensure the safe and beneficial use of these herbal medicines. Georg Thieme Verlag KG Stuttgart.New York.

Evaluation of a 3D diamond detector for medical radiation dosimetry

NASA Astrophysics Data System (ADS)

Kanxheri, K.; Servoli, L.; Oh, A.; Munoz Sanchez, F.; Forcolin, G. T.; Murphy, S. A.; Aitkenhead, A.; Moore, C. J.; Morozzi, A.; Passeri, D.; Bellini, M.; Corsi, C.; Lagomarsino, S.; Sciortino, S.

2017-01-01

Synthetic diamond has several properties that are particularly suited to applications in medical radiation dosimetry. It is tissue equivalent, not toxic and shows a high resistance to radiation damage, low leakage current and stability of response. It is an electrical insulator, robust and realizable in small size; due to these features there are several examples of diamond devices, mainly planar single-crystalline chemical vapor depositation (sCVD) diamond, used for relative dose measurement in photon beams. Thanks to a new emerging technology, diamond devices with 3-dimensional structures are produced by using laser pulses to create graphitic paths in the diamond bulk. The necessary bias voltage to operate such detector decreases considerably while the signal response and radiation resistance increase. In order to evaluate the suitability of this new technology for measuring the dose delivered by radiotherapy beams in oncology a 3D polycrystalline (pCVD) diamond detector designed for single charged particle detection has been tested and the photon beam profile has been studied. The good linearity and high sensitivity to the dose observed in the 3D diamond, opens the way to the possibility of realizing a finely segmented device with the potential for dose distribution measurement in a single exposure for small field dosimetry that nowadays is still extremely challenging.

Single dose x irradiation and concomitant hyperthermia on a murine fibroscarcoma. [Sensitizing effects of hyperthermia on tumors in mice subjected to local radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hahn, E.W.; Alfieri, A.A.; Kim, J.H.

1978-12-01

The objectives of this study were to quantitate the effects of local tumor hyperthermia (LTH) and concomitant x irradiation (RAD) on a moderately radioresistant murine fibrosarcoma in situ. Comparisons were made to the combined treatment response on the Ridgway osteogenic sarcoma, a radiosensitive tumor previously used in this laboratory and to establish the Meth-A fibrosarcoma as a model system for combined modality studies. 1.0 cm/sup 3/ tumors were exposed to single doses of RAD ranging from 0.5 to 3.8 krad alone or 0.5 to 2.3 krad in combination with LTH (water bath at 43.1 +- .05 C for 20 minutes)more » applied immediately postirradiation. LTH significantly enhanced the action of radiation as measured by tumor volume analysis, mean survival time and cures. The ratio of radiation doses vs. RAD + LTH required to produce an equivalent response ranged from 1.4 to 2.5 depending upon the endpoints evaluated. These findings are consistent with single dose studies on the radiosensitive Ridgway osteogenic sarcoma and suggest that the tumoricidal effectiveness of combination radiation and hyperthermia cannot be predicted on the basis of the radiation alone responsiveness of tumor.« less

Equivalent square formula for determining the surface dose of rectangular field from 6 MV therapeutic photon beam.

PubMed

Apipunyasopon, Lukkana; Srisatit, Somyot; Phaisangittisakul, Nakorn

2013-09-06

The purpose of the study was to investigate the use of the equivalent square formula for determining the surface dose from a rectangular photon beam. A 6 MV therapeutic photon beam delivered from a Varian Clinac 23EX medical linear accelerator was modeled using the EGS4nrc Monte Carlo simulation package. It was then used to calculate the dose in the build-up region from both square and rectangular fields. The field patterns were defined by various settings of the X- and Y-collimator jaw ranging from 5 to 20 cm. Dose measurements were performed using a thermoluminescence dosimeter and a Markus parallel-plate ionization chamber on the four square fields (5 × 5, 10 × 10, 15 × 15, and 20 × 20 cm2). The surface dose was acquired by extrapolating the build-up doses to the surface. An equivalent square for a rectangular field was determined using the area-to-perimeter formula, and the surface dose of the equivalent square was estimated using the square-field data. The surface dose of square field increased linearly from approximately 10% to 28% as the side of the square field increased from 5 to 20 cm. The influence of collimator exchange on the surface dose was found to be not significant. The difference in the percentage surface dose of the rectangular field compared to that of the relevant equivalent square was insignificant and can be clinically neglected. The use of the area-to-perimeter formula for an equivalent square field can provide a clinically acceptable surface dose estimation for a rectangular field from a 6 MV therapy photon beam.

Monte Carlo calculation of the neutron dose to a fetus at commercial flight altitudes

NASA Astrophysics Data System (ADS)

Alves, M. C.; Galeano, D. C.; Santos, W. S.; Hunt, John G.; d'Errico, Francesco; Souza, S. O.; de Carvalho Júnior, A. B.

2017-11-01

Aircrew members are exposed to primary cosmic rays as well as to secondary radiations from the interaction of cosmic rays with the atmosphere and with the aircraft. The radiation field at flight altitudes comprises neutrons, protons, electrons, positrons, photons, muons and pions. Generally, 50% of the effective dose to airplane passengers is due to neutrons. Care must be taken especially with pregnant aircrew members and frequent fliers so that the equivalent dose to the fetus will not exceed prescribed limits during pregnancy (1 mSv according to ICRP, and 5 mSv according to NCRP). Therefore, it is necessary to evaluate the equivalent dose to a fetus in the maternal womb. Up to now, the equivalent dose rate to a fetus at commercial flight altitudes was obtained using stylized pregnant-female phantom models. The aim of this study was calculating neutron fluence to dose conversion coefficients for a fetus of six months of gestation age using a new, realistic pregnant-female mesh-phantom. The equivalent dose rate to a fetus during an intercontinental flight was also calculated by folding our conversion coefficients with published spectral neutron flux data. The calculated equivalent dose rate to the fetus was 2.35 μSv.h-1, that is 1.5 times higher than equivalent dose rates reported in the literature. The neutron fluence to dose conversion coefficients for the fetus calculated in this study were 2.7, 3.1 and 3.9 times higher than those from previous studies using fetus models of 3, 6 and 9 months of gestation age, respectively. The differences between our study and data from the literature highlight the importance of using more realistic anthropomorphic phantoms to estimate doses to a fetus in pregnant aircrew members.

A randomised, single-blind, single-dose, three-arm, parallel-group study in healthy subjects to demonstrate pharmacokinetic equivalence of ABP 501 and adalimumab

PubMed Central

Kaur, Primal; Chow, Vincent; Zhang, Nan; Moxness, Michael; Kaliyaperumal, Arunan; Markus, Richard

2017-01-01

Objective To demonstrate pharmacokinetic (PK) similarity of biosimilar candidate ABP 501 relative to adalimumab reference product from the USA and European Union (EU) and evaluate safety, tolerability and immunogenicity of ABP 501. Methods Randomised, single-blind, single-dose, three-arm, parallel-group study; healthy subjects were randomised to receive ABP 501 (n=67), adalimumab (USA) (n=69) or adalimumab (EU) (n=67) 40 mg subcutaneously. Primary end points were area under the serum concentration-time curve from time 0 extrapolated to infinity (AUCinf) and the maximum observed concentration (Cmax). Secondary end points included safety and immunogenicity. Results AUCinf and Cmax were similar across the three groups. Geometrical mean ratio (GMR) of AUCinf was 1.11 between ABP 501 and adalimumab (USA), and 1.04 between ABP 501 and adalimumab (EU). GMR of Cmax was 1.04 between ABP 501 and adalimumab (USA) and 0.96 between ABP 501 and adalimumab (EU). The 90% CIs for the GMRs of AUCinf and Cmax were within the prespecified standard PK equivalence criteria of 0.80 to 1.25. Treatment-related adverse events were mild to moderate and were reported for 35.8%, 24.6% and 41.8% of subjects in the ABP 501, adalimumab (USA) and adalimumab (EU) groups; incidence of antidrug antibodies (ADAbs) was similar among the study groups. Conclusions Results of this study demonstrated PK similarity of ABP 501 with adalimumab (USA) and adalimumab (EU) after a single 40-mg subcutaneous injection. No new safety signals with ABP 501 were identified. The safety and tolerability of ABP 501 was similar to the reference products, and similar ADAb rates were observed across the three groups. Trial registration number EudraCT number 2012-000785-37; Results. PMID:27466231

10 CFR 63.111 - Performance objectives for the geologic repository operations area through permanent closure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... of the deep dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose equivalent may not exceed 0.15 Sv (15... TEDE (hereafter referred to as “dose”) to any real member of the public located beyond the boundary of...

10 CFR 63.111 - Performance objectives for the geologic repository operations area through permanent closure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... of the deep dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose equivalent may not exceed 0.15 Sv (15... TEDE (hereafter referred to as “dose”) to any real member of the public located beyond the boundary of...

10 CFR 63.111 - Performance objectives for the geologic repository operations area through permanent closure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... of the deep dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose equivalent may not exceed 0.15 Sv (15... TEDE (hereafter referred to as “dose”) to any real member of the public located beyond the boundary of...

10 CFR 63.111 - Performance objectives for the geologic repository operations area through permanent closure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... of the deep dose equivalent and the committed dose equivalent to any individual organ or tissue (other than the lens of the eye) of 0.5 Sv (50 rem). The lens dose equivalent may not exceed 0.15 Sv (15... TEDE (hereafter referred to as “dose”) to any real member of the public located beyond the boundary of...

Pharmacokinetic profiles of a biosimilar filgrastim and Amgen filgrastim: results from a randomized, phase I trial

PubMed Central

Bronchud, Miguel; Mair, Stuart; Challand, Rodeina

2010-01-01

Recombinant human granulocyte colony-stimulating factor (filgrastim) has multiple hematologic and oncologic indications as Neupogen® (Amgen filgrastim). Hospira has developed a biosimilar filgrastim (Nivestim™). Here, results are reported from a phase I trial, primarily designed to compare the pharmacokinetic profiles of Hospira filgrastim and Amgen filgrastim. A phase I, single-center, open-label, randomized trial was undertaken to demonstrate equivalence of the pharmacokinetic characteristics of Hospira filgrastim and Amgen filgrastim. Forty-eight healthy volunteers were randomized to receive intravenous (i.v.) or subcutaneous (s.c.) dosing and then further randomized to order of treatment. Volunteers in each of the two dosing groups received a single 10µg/kg dose of Hospira filgrastim or Amgen filgrastim, with subsequent crossover. Bioequivalence was evaluated by analysis of variance; if the estimated 90% confidence intervals (CIs) for the ratio of ‘test’ to ‘reference’ treatment means were within the conventional equivalence limits of 0.80–1.25, then bioequivalence was concluded. Forty-six volunteers completed the study. Geometric mean area under the curve from time 0 to the last time point (primary endpoint) was similar in volunteers given Hospira filgrastim or Amgen filgrastim following i.v. (ratio of means: 0.96; 90% CI: 0.90–1.02) or s.c. (ratio of means: 1.02; 90% CI: 0.95–1.09) dosing; 90% CIs were within the predefined range necessary to demonstrate bioequivalence. Hospira filgrastim was well tolerated with no additional safety concerns over Amgen filgrastim. Hospira filgrastim is bioequivalent with Amgen filgrastim in terms of its pharmacokinetic properties and may provide a clinically effective alternative. PMID:20428872

Testing Moderating Detection Systems with {sup 252}Cf-Based Reference Neutron Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hertel, Nolan E.; Sweezy, Jeremy; Sauber, Jeremiah S.

Calibration measurements were carried out on a probe designed to measure ambient dose equivalent in accordance with ICRP Pub 60 recommendations. It consists of a cylindrical {sup 3}He proportional counter surrounded by a 25-cm-diameter spherical polyethylene moderator. Its neutron response is optimized for dose rate measurements of neutrons between thermal energies and 20 MeV. The instrument was used to measure the dose rate in four separate neutron fields: unmoderated {sup 252}Cf, D{sub 2}O-moderated {sup 252}Cf, polyethylene-moderated {sup 252}Cf, and WEP neutron howitzer with {sup 252}Cf at its center. Dose equivalent measurements were performed at source-detector centerline distances from 50 tomore » 200 cm. The ratio of air-scatter- and room-return-corrected ambient dose equivalent rates to ambient dose equivalent rates calculated with the code MCNP are tabulated.« less

Equivalence in Dose Fall-Off for Isocentric and Nonisocentric Intracranial Treatment Modalities and Its Impact on Dose Fractionation Schemes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma Lijun, E-mail: lijunma@radonc.ucsf.ed; Sahgal, Arjun; Descovich, Martina

2010-03-01

Purpose: To investigate whether dose fall-off characteristics would be significantly different among intracranial radiosurgery modalities and the influence of these characteristics on fractionation schemes in terms of normal tissue sparing. Methods and Materials: An analytic model was developed to measure dose fall-off characteristics near the target independent of treatment modalities. Variations in the peripheral dose fall-off characteristics were then examined and compared for intracranial tumors treated with Gamma Knife, Cyberknife, or Novalis LINAC-based system. Equivalent uniform biologic effective dose (EUBED) for the normal brain tissue was calculated. Functional dependence of the normal brain EUBED on varying numbers of fractions (1more » to 30) was studied for the three modalities. Results: The derived model fitted remarkably well for all the cases (R{sup 2} > 0.99). No statistically significant differences in the dose fall-off relationships were found between the three modalities. Based on the extent of variations in the dose fall-off curves, normal brain EUBED was found to decrease with increasing number of fractions for the targets, with alpha/beta ranging from 10 to 20. This decrease was most pronounced for hypofractionated treatments with fewer than 10 fractions. Additionally, EUBED was found to increase slightly with increasing number of fractions for targets with alpha/beta ranging from 2 to 5. Conclusion: Nearly identical dose fall-off characteristics were found for the Gamma Knife, Cyberknife, and Novalis systems. Based on EUBED calculations, normal brain sparing was found to favor hypofractionated treatments for fast-growing tumors with alpha/beta ranging from 10 to 20 and single fraction treatment for abnormal tissues with low alpha/beta values such as alpha/beta = 2.« less

The effect of a paraffin screen on the neutron dose at the maze door of a 15 MV linear accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krmar, M.; Kuzmanović, A.; Nikolić, D.

2013-08-15

Purpose: The purpose of this study was to explore the effects of a paraffin screen located at various positions in the maze on the neutron dose equivalent at the maze door.Methods: The neutron dose equivalent was measured at the maze door of a room containing a 15 MV linear accelerator for x-ray therapy. Measurements were performed for several positions of the paraffin screen covering only 27.5% of the cross-sectional area of the maze. The neutron dose equivalent was also measured at all screen positions. Two simple models of the neutron source were considered in which the first assumed that themore » source was the cross-sectional area at the inner entrance of the maze, radiating neutrons in an isotropic manner. In the second model the reduction in the neutron dose equivalent at the maze door due to the paraffin screen was considered to be a function of the mean values of the neutron fluence and energy at the screen.Results: The results of this study indicate that the equivalent dose at the maze door was reduced by a factor of 3 through the use of a paraffin screen that was placed inside the maze. It was also determined that the contributions to the dosage from areas that were not covered by the paraffin screen as viewed from the dosimeter, were 2.5 times higher than the contributions from the covered areas. This study also concluded that the contributions of the maze walls, ceiling, and floor to the total neutron dose equivalent were an order of magnitude lower than those from the surface at the far end of the maze.Conclusions: This study demonstrated that a paraffin screen could be used to reduce the neutron dose equivalent at the maze door by a factor of 3. This paper also found that the reduction of the neutron dose equivalent was a linear function of the area covered by the maze screen and that the decrease in the dose at the maze door could be modeled as an exponential function of the product φ·E at the screen.« less

NUNDO: a numerical model of a human torso phantom and its application to effective dose equivalent calculations for astronauts at the ISS.

PubMed

Puchalska, Monika; Bilski, Pawel; Berger, Thomas; Hajek, Michael; Horwacik, Tomasz; Körner, Christine; Olko, Pawel; Shurshakov, Vyacheslav; Reitz, Günther

2014-11-01

The health effects of cosmic radiation on astronauts need to be precisely quantified and controlled. This task is important not only in perspective of the increasing human presence at the International Space Station (ISS), but also for the preparation of safe human missions beyond low earth orbit. From a radiation protection point of view, the baseline quantity for radiation risk assessment in space is the effective dose equivalent. The present work reports the first successful attempt of the experimental determination of the effective dose equivalent in space, both for extra-vehicular activity (EVA) and intra-vehicular activity (IVA). This was achieved using the anthropomorphic torso phantom RANDO(®) equipped with more than 6,000 passive thermoluminescent detectors and plastic nuclear track detectors, which have been exposed to cosmic radiation inside the European Space Agency MATROSHKA facility both outside and inside the ISS. In order to calculate the effective dose equivalent, a numerical model of the RANDO(®) phantom, based on computer tomography scans of the actual phantom, was developed. It was found that the effective dose equivalent rate during an EVA approaches 700 μSv/d, while during an IVA about 20 % lower values were observed. It is shown that the individual dose based on a personal dosimeter reading for an astronaut during IVA results in an overestimate of the effective dose equivalent of about 15 %, whereas under an EVA conditions the overestimate is more than 200 %. A personal dosemeter can therefore deliver quite good exposure records during IVA, but may overestimate the effective dose equivalent received during an EVA considerably.

Effects of caffeine on mood and performance: a study of realistic consumption.

PubMed

Brice, Carolyn F; Smith, Andrew P

2002-11-01

There is a vast literature on the behavioural effects of caffeine. Many of the studies have involved single administration of a large dose of caffeine that is not representative of the way in which caffeine is usually ingested. Further information is required, therefore, on the behavioural effects of realistic patterns of consumption. The present study aimed to determine whether a realistic drinking regime (multiple small doses - 4 x 65 mg over a 5-h period) produced the same effects as a single large dose (200 mg). The smaller doses were selected so that the amount of caffeine present in the body after 5 h would be equivalent to that found with the single dose. A double-blind, placebo-controlled, within-subjects experiment was, therefore, carried out. The participants ( n=24) attended for four sessions. Each session started with a baseline measurement of mood and performance at 0930 hours. On two of the sessions, coffee was then consumed at 1000, 1100, 1200 and 1300 hours. In one of these sessions 65 mg caffeine was added to the de-caffeinated coffee. In the other two sessions, the participants consumed coffee at 1300 hours and 200 mg caffeine was added in one of the sessions. The volunteers completed the battery of tests again at 1500 hours. The results showed that in both consumption regimes caffeine led to increased alertness and anxiety and improved performance on simple and choice reactive tasks, a cognitive vigilance task, a task requiring sustained response and a dual task involving tracking and target detection. These results suggest that previous findings from studies using a large single dose may be applicable to normal patterns of caffeine consumption.

Phase I/II trial of single-fraction high-dose-rate brachytherapy-boosted hypofractionated intensity-modulated radiation therapy for localized adenocarcinoma of the prostate.

PubMed

Myers, Michael A; Hagan, Michael P; Todor, Dorin; Gilbert, Lynn; Mukhopadhyay, Nitai; Randolf, Jessica; Heimiller, Jeffrey; Anscher, Mitchell S

2012-01-01

A Phase I/II protocol was conducted to examine the toxicity and efficacy of the combination of intensity-modulated radiation therapy (IMRT) with a single-fraction high-dose-rate (HDR) brachytherapy implant. From 2001 through 2006, 26 consecutive patients were treated on the trial. The primary objective was to demonstrate a high rate of completion without experiencing a treatment-limiting toxicity. Eligibility was limited to patients with T stage ≤2b, prostate-specific antigen (PSA) ≤20, and Gleason score ≤7. Treatment began with a single HDR fraction of 6Gy to the entire prostate and 9Gy to the peripheral zone, followed by IMRT optimized to deliver in 28 fractions with a normalized total dose of 70Gy. Patients received 50.4Gy to the pelvic lymph node. The prostate dose (IMRT and HDR) resulted in an average biologic equivalent dose >128Gy (α/β=3). Patients whose pretreatment PSA was ≥10ng/mL, Gleason score 7, or stage ≥T2b received short-term androgen ablation. Median followup was 53 months (9-68 months). There were no biochemical failures by either the American Society of Therapeutic Radiology and Oncology or the Phoenix definitions. The median nadir PSA was 0.32ng/mL. All the 26 patients completed the treatment as prescribed. The rate of Grade 3 late genitourinary toxicity was 3.8% consisting of a urethral stricture. There was no other Grade 3 or 4 genitourinary or gastrointestinal toxicities. Single-fraction HDR-boosted IMRT is a safe effective method of dose escalation for localized prostate cancer. Copyright © 2012 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Response of puppies to canine-origin parvovirus vaccines.

PubMed

Carmichael, L E; Pollock, R V; Joubert, J C

1984-02-01

Pups 9-18 1/2 weeks old were given a single dose of 1 of 4 commercial, live, canine-origin parvovirus vaccines. All 4 vaccines evoked high levels of antibody in seronegative pups, but variable response in those with low levels of maternally derived antibodies. Vaccinal virus spread to unvaccinated contact controls and elicited essentially equivalent titers. No clinical signs of parvovirus infection were observed in vaccinates or controls.

Papillary Necrosis in Experimental Analgesic Nephropathy

PubMed Central

Saker, B. M.; Kincaid-Smith, Priscilla

1969-01-01

A proprietary aspirin, phenacetin, and caffeine preparation given to rats in a dose equivalent to that taken by patients with analgesic nephropathy produced papillary necrosis in 55%. There was a higher incidence in rats deprived of fluids overnight. Papillary necrosis was not noted in rats receiving twice as much phenacetin. These findings support the argument that phenacetin should not be singled out as the substance responsible for analgesic nephropathy in man. PMID:5762278

Bioavailability of cyanide after consumption of a single meal of foods containing high levels of cyanogenic glycosides: a crossover study in humans.

PubMed

Abraham, Klaus; Buhrke, Thorsten; Lampen, Alfonso

2016-03-01

The acute toxicity of cyanide is determined by its peak levels reached in the body. Compared to the ingestion of free cyanide, lower peak levels may be expected after consumption of foods containing cyanogenic glycosides with the same equivalent dose of cyanide. This is due to possible delayed and/or incomplete release of cyanide from the cyanogenic glycosides depending on many factors. Data on bioavailability of cyanide after consumption of foods containing high levels of cyanogenic glycosides as presented herein were necessary to allow a meaningful risk assessment for these foods. A crossover study was carried out in 12 healthy adults who consumed persipan paste (equivalent total cyanide: 68 mg/kg), linseed (220 mg/kg), bitter apricot kernels (about 3250 mg/kg), and fresh cassava roots (76-150 mg/kg), with each "meal" containing equivalents of 6.8 mg cyanide. Cyanide levels were determined in whole blood using a GC-MS method with K(13)C(15)N as internal standard. Mean levels of cyanide at the different time points were highest after consumption of cassava (15.4 µM, after 37.5 min) and bitter apricot kernels (14.3 µM, after 20 min), followed by linseed (5.7 µM, after 40 min) and 100 g persipan (1.3 µM, after 105 min). The double dose of 13.6 mg cyanide eaten with 200 g persipan paste resulted in a mean peak level of 2.9 µM (after 150 min). An acute reference dose of 0.075 mg/kg body weight was derived being valid for a single application/meal of cyanides or hydrocyanic acid as well as of unprocessed foods with cyanogenic glycosides also containing the accompanying intact β-glucosidase. For some of these foods, this approach may be overly conservative due to delayed release of cyanide, as demonstrated for linseed. In case of missing or inactivated β-glucosidase, the hazard potential is much lower.

A randomized, single-blind, single-dose study evaluating the pharmacokinetic equivalence of proposed biosimilar ABP 980 and trastuzumab in healthy male subjects.

PubMed

Hanes, Vladimir; Chow, Vincent; Zhang, Nan; Markus, Richard

2017-05-01

This study compared the pharmacokinetic (PK) profiles of the proposed biosimilar ABP 980 and trastuzumab in healthy males. In this single-blind study, 157 healthy males were randomized 1:1:1 to a single 6 mg/kg intravenous infusion of ABP 980, FDA-licensed trastuzumab [trastuzumab (US)], or EU-authorized trastuzumab [trastuzumab (EU)]. Primary endpoints were area under the serum concentration-time curve from time 0 to infinity (AUC inf ) and maximum observed serum concentration (C max ). To establish equivalence, the geometric mean ratio (GMR) and 90% confidence interval (CI) for C max and AUC inf had to be within the equivalence criteria of 0.80-1.25. The GMRs and 90% CIs for C max and AUC inf , respectively, were: 1.04 (0.99-1.08) and 1.06 (1.00-1.12) for ABP 980 versus trastuzumab (US); 0.99 (0.95-1.03) and 1.00 (0.95-1.06) for ABP 980 versus trastuzumab (EU); and 0.96 (0.92-1.00) and 0.95 (0.90-1.01) for trastuzumab (US) versus trastuzumab (EU). All comparisons were within the equivalence criteria of 0.80-1.25. Treatment-emergent adverse events (TEAEs) were reported in 84.0, 75.0, and 78.2 of subjects in the ABP 980, trastuzumab (US), and trastuzumab (EU) groups, respectively. There were no deaths or TEAEs leading to study discontinuation and no binding or neutralizing anti-drug anti-bodies were detected. This study demonstrated the PK similarity of ABP 980 to both trastuzumab (US) and trastuzumab (EU), and of trastuzumab (US) to trastuzumab (EU). No differences in safety and tolerability between treatments were noted; no subject tested positive for binding anti-bodies.

Calculated organ doses from selected prostate treatment plans using Monte Carlo simulations and an anatomically realistic computational phantom

PubMed Central

Bednarz, Bryan; Hancox, Cindy; Xu, X George

2012-01-01

There is growing concern about radiation-induced second cancers associated with radiation treatments. Particular attention has been focused on the risk to patients treated with intensity-modulated radiation therapy (IMRT) due primarily to increased monitor units. To address this concern we have combined a detailed medical linear accelerator model of the Varian Clinac 2100 C with anatomically realistic computational phantoms to calculate organ doses from selected treatment plans. This paper describes the application to calculate organ-averaged equivalent doses using a computational phantom for three different treatments of prostate cancer: a 4-field box treatment, the same box treatment plus a 6-field 3D-CRT boost treatment and a 7-field IMRT treatment. The equivalent doses per MU to those organs that have shown a predilection for second cancers were compared between the different treatment techniques. In addition, the dependence of photon and neutron equivalent doses on gantry angle and energy was investigated. The results indicate that the box treatment plus 6-field boost delivered the highest intermediate- and low-level photon doses per treatment MU to the patient primarily due to the elevated patient scatter contribution as a result of an increase in integral dose delivered by this treatment. In most organs the contribution of neutron dose to the total equivalent dose for the 3D-CRT treatments was less than the contribution of photon dose, except for the lung, esophagus, thyroid and brain. The total equivalent dose per MU to each organ was calculated by summing the photon and neutron dose contributions. For all organs non-adjacent to the primary beam, the equivalent doses per MU from the IMRT treatment were less than the doses from the 3D-CRT treatments. This is due to the increase in the integral dose and the added neutron dose to these organs from the 18 MV treatments. However, depending on the application technique and optimization used, the required MU values for IMRT treatments can be two to three times greater than 3D CRT. Therefore, the total equivalent dose in most organs would be higher from the IMRT treatment compared to the box treatment and comparable to the organ doses from the box treatment plus the 6-field boost. This is the first time when organ dose data for an adult male patient of the ICRP reference anatomy have been calculated and documented. The tools presented in this paper can be used to estimate the second cancer risk to patients undergoing radiation treatment. PMID:19671968

Calculated organ doses from selected prostate treatment plans using Monte Carlo simulations and an anatomically realistic computational phantom

NASA Astrophysics Data System (ADS)

Bednarz, Bryan; Hancox, Cindy; Xu, X. George

2009-09-01

There is growing concern about radiation-induced second cancers associated with radiation treatments. Particular attention has been focused on the risk to patients treated with intensity-modulated radiation therapy (IMRT) due primarily to increased monitor units. To address this concern we have combined a detailed medical linear accelerator model of the Varian Clinac 2100 C with anatomically realistic computational phantoms to calculate organ doses from selected treatment plans. This paper describes the application to calculate organ-averaged equivalent doses using a computational phantom for three different treatments of prostate cancer: a 4-field box treatment, the same box treatment plus a 6-field 3D-CRT boost treatment and a 7-field IMRT treatment. The equivalent doses per MU to those organs that have shown a predilection for second cancers were compared between the different treatment techniques. In addition, the dependence of photon and neutron equivalent doses on gantry angle and energy was investigated. The results indicate that the box treatment plus 6-field boost delivered the highest intermediate- and low-level photon doses per treatment MU to the patient primarily due to the elevated patient scatter contribution as a result of an increase in integral dose delivered by this treatment. In most organs the contribution of neutron dose to the total equivalent dose for the 3D-CRT treatments was less than the contribution of photon dose, except for the lung, esophagus, thyroid and brain. The total equivalent dose per MU to each organ was calculated by summing the photon and neutron dose contributions. For all organs non-adjacent to the primary beam, the equivalent doses per MU from the IMRT treatment were less than the doses from the 3D-CRT treatments. This is due to the increase in the integral dose and the added neutron dose to these organs from the 18 MV treatments. However, depending on the application technique and optimization used, the required MU values for IMRT treatments can be two to three times greater than 3D CRT. Therefore, the total equivalent dose in most organs would be higher from the IMRT treatment compared to the box treatment and comparable to the organ doses from the box treatment plus the 6-field boost. This is the first time when organ dose data for an adult male patient of the ICRP reference anatomy have been calculated and documented. The tools presented in this paper can be used to estimate the second cancer risk to patients undergoing radiation treatment.

Single-energy pediatric chest computed tomography with spectral filtration at 100 kVp: effects on radiation parameters and image quality.

PubMed

Bodelle, Boris; Fischbach, Constanze; Booz, Christian; Yel, Ibrahim; Frellesen, Claudia; Kaup, Moritz; Beeres, Martin; Vogl, Thomas J; Scholtz, Jan-Erik

2017-06-01

Most of the applied radiation dose at CT is in the lower photon energy range, which is of limited diagnostic importance. To investigate image quality and effects on radiation parameters of 100-kVp spectral filtration single-energy chest CT using a tin-filter at third-generation dual-source CT in comparison to standard 100-kVp chest CT. Thirty-three children referred for a non-contrast chest CT performed on a third-generation dual-source CT scanner were examined at 100 kVp with a dedicated tin filter with a tube current-time product resulting in standard protocol dose. We compared resulting images with images from children examined using standard single-source chest CT at 100 kVp. We assessed objective and subjective image quality and compared radiation dose parameters. Radiation dose was comparable for children 5 years old and younger, and it was moderately decreased for older children when using spectral filtration (P=0.006). Effective tube current increased significantly (P=0.0001) with spectral filtration, up to a factor of 10. Signal-to-noise ratio and image noise were similar for both examination techniques (P≥0.06). Subjective image quality showed no significant differences (P≥0.2). Using 100-kVp spectral filtration chest CT in children by means of a tube-based tin-filter on a third-generation dual-source CT scanner increases effective tube current up to a factor of 10 to provide similar image quality at equivalent dose compared to standard single-source CT without spectral filtration.

A Long-Acting Human Growth Hormone With Delayed Clearance (VRS-317): Results of a Double-Blind, Placebo-Controlled, Single Ascending Dose Study in Growth Hormone–Deficient Adults

PubMed Central

Yuen, Kevin C. J.; Conway, Gerard S.; Popovic, Vera; Merriam, George R.; Bailey, Timothy; Hamrahian, Amir H.; Biller, Beverly M. K.; Kipnes, Mark; Moore, Jerome A.; Humphriss, Eric; Cleland, Jeffrey L.

2013-01-01

Background: Administration of daily recombinant human GH (rhGH) poses a considerable challenge to patient compliance. Reduced dosing frequency may improve treatment adherence and potentially overall treatment outcomes. Objectives: This study assessed the safety and tolerability and the potential for achieving IGF-I levels within the target range in adults with GH deficiency after a single dose of the long-acting rhGH analog, VRS-317. Design: This was a randomized, double-blind, placebo-controlled, single ascending dose study. Patients: Fifty adults with growth hormone deficiency (mean age, 45 years) were studied in 5 treatment groups of 10 subjects each (8 active drug and 2 placebo). Setting: The study was conducted in 17 adult endocrinology centers in North America and Europe. Main Outcome Measures: Adverse events, laboratory safety assessments, and VRS-317 pharmacokinetics and pharmacodynamics (IGF-I and IGF binding protein-3) were analyzed. Results: At 0.80 mg/kg, VRS-317 had a mean terminal elimination half-life of 131 hours. Single VRS-317 doses of 0.05, 0.10, 0.20, 0.40, and 0.80 mg/kg (approximately equivalent to daily rhGH doses of 0.3–5.0 μg/kg over 30 d) safely increased the amplitude and duration of IGF-I responses in a dose-dependent manner. After a single 0.80 mg/kg dose, serum IGF-I was maintained in the normal range between −1.5 and 1.5 SD values for a mean of 3 weeks. No unexpected or serious adverse events were observed. Conclusions: The elimination half-life for VRS-317 is 30- to 60-fold longer and stimulates more durable IGF-I responses than previously studied rhGH products. Prolonged IGF-I responses do not come at the expense of overexposure to high IGF-I levels. The pharmacokinetics and pharmacodynamics combined with the observed safety profile indicate the potential for safe and effective monthly dosing. PMID:23585663

Neutron dosimetry in low-earth orbit using passive detectors

NASA Technical Reports Server (NTRS)

Benton, E. R.; Benton, E. V.; Frank, A. L.

2001-01-01

This paper summarizes neutron dosimetry measurements made by the USF Physics Research Laboratory aboard US and Russian LEO spacecraft over the past 20 years using two types of passive detector. Thermal/resonance neutron detectors exploiting the 6Li(n,T) alpha reaction were used to measure neutrons of energies <1 MeV. Fission foil neutron detectors were used to measure neutrons of energies above 1 MeV. While originally analysed in terms of dose equivalent using the NCRP-38 definition of quality factor, for the purposes of this paper the measured neutron data have been reanalyzed and are presented in terms of ambient dose equivalent. Dose equivalent rate for neutrons <1 MeV ranged from 0.80 microSv/d on the low altitude, low inclination STS-41B mission to 22.0 microSv/d measured in the Shuttle's cargo bay on the highly inclined STS-51F Spacelab-2 mission. In one particular instance a detector embedded within a large hydrogenous mass on STS-61 (in the ECT experiment) measured 34.6 microSv/d. Dose equivalent rate measurements of neutrons >1 MeV ranged from 4.5 microSv/d on the low altitude STS-3 mission to 172 microSv/d on the 6 year LDEF mission. Thermal neutrons (<0.3 eV) were observed to make a negligible contribution to neutron dose equivalent in all cases. The major fraction of neutron dose equivalent was found to be from neutrons >1 MeV and, on LDEF, neutrons >1 MeV are responsible for over 98% of the total neutron dose equivalent. Estimates of the neutron contribution to the total dose equivalent are somewhat lower than model estimates, ranging from 5.7% at a location under low shielding on LDEF to 18.4% on the highly inclined (82.3 degrees) Biocosmos-2044 mission. c2001 Elsevier Science Ltd. All rights reserved.

SU-E-I-49: Influence of Scanner Output Measurement Technique on KERMA Ratios in CT.

PubMed

Ogden, K; Roskopf, M; Scalzetti, E

2012-06-01

KERMA ratios (RK) are defined as the ratio of KERMA measured at a specific phantom location (K) to in-air isocenter CT scanner output (KCT). In this work we investigate the impact of measurement methodology on KCT values. OSL dosimeter chips were used to measure KCT for a GE VCT scanner (GE Medical Systems, Waukesha WI), using the 40 mm nominal beam width. Methods included a single point measurement at the center of the beam (1 tube rotation), and extended z-axis measurements using multiple adjacent OSL's (7.5 cm extent), with single tube rotation, multiple contiguous axial scans, and helical scans (pitch of 1.375). Measurements were made in air and on the scan table at 80 and 120 kV. Averaged single point measurements were consistent, with a mean coefficient of variation of 2.5%. For extended measurements with a single tube rotation, the mean value was equivalent to the single point measurements. For multiple contiguous axial scans, the in-air KCT values were higher than the single rotation mean value and single point measurements by 13% and 10.3% at 120 and 80 kV, respectively, and for the on-table measurements the values were 14.9% and 8.1% higher at 120 and 80 kV, respectively. The increase is due to beam overlap caused by z- axis over-beaming. Extended measurements using helical scanning were equivalent to the multiple rotation axial measurements when corrected for the helical pitch. For all methodologies, the in-air values exceeded the on- table measurements by an average of 23% and 19.4% at 80 and 120 kV, respectively. Scanner KCT values must be measured to allow organ dose estimation using published RK values. It is imperative that the KCT measurement methodology is the same as for the published values, or large errors may be introduced into the resulting organ dose estimates. © 2012 American Association of Physicists in Medicine.

A new formula for normal tissue complication probability (NTCP) as a function of equivalent uniform dose (EUD).

PubMed

Luxton, Gary; Keall, Paul J; King, Christopher R

2008-01-07

To facilitate the use of biological outcome modeling for treatment planning, an exponential function is introduced as a simpler equivalent to the Lyman formula for calculating normal tissue complication probability (NTCP). The single parameter of the exponential function is chosen to reproduce the Lyman calculation to within approximately 0.3%, and thus enable easy conversion of data contained in empirical fits of Lyman parameters for organs at risk (OARs). Organ parameters for the new formula are given in terms of Lyman model m and TD(50), and conversely m and TD(50) are expressed in terms of the parameters of the new equation. The role of the Lyman volume-effect parameter n is unchanged from its role in the Lyman model. For a non-homogeneously irradiated OAR, an equation relates d(ref), n, v(eff) and the Niemierko equivalent uniform dose (EUD), where d(ref) and v(eff) are the reference dose and effective fractional volume of the Kutcher-Burman reduction algorithm (i.e. the LKB model). It follows in the LKB model that uniform EUD irradiation of an OAR results in the same NTCP as the original non-homogeneous distribution. The NTCP equation is therefore represented as a function of EUD. The inverse equation expresses EUD as a function of NTCP and is used to generate a table of EUD versus normal tissue complication probability for the Emami-Burman parameter fits as well as for OAR parameter sets from more recent data.

Doses effects of zoledronic acid on mineral apatite and collagen quality of newly-formed bone in the rat's calvaria defect.

PubMed

Olejnik, Cécile; Falgayrac, Guillaume; During, Alexandrine; Cortet, Bernard; Penel, Guillaume

2016-08-01

Due to their inhibitory effects on resorption, bisphosphonates are widely used in the treatment of diseases associated to an extensive bone loss. Yet, little is known about bisphosphonates effects on newly-formed bone quality. In the present study, adult male Sprague-Dawley rats (n=80) with a bone defect calvaria area were used and short-term effects of zoledronic acid (ZA) were studied on the healing bone area. Three ZA treatments were tested by using either: 1°) a low single dose (120μgZA/kg, n=10; equivalent to human osteoporosis treatment), 2°) a low fractionated doses (20μgZA/kg daily for 6days either a total of 120μg/kg, n=15), and 3°) a high fractionated doses, (100μgZA/kg weekly for 6weeks, n=15; equivalent to 6months of human bone metastasis treatment). For each treatment, a control "vehicle" treatment was performed (with an identical number of rats). After ZA administration, the intrinsic bone material properties were evaluated by quantitative backscattered electron imaging (qBEI) and Raman microspectroscopy. Neither single nor fractionated low ZA doses modify the intrinsic bone material properties of the newly-formed bone compared to their respective control animals. On the opposite, the high ZA treatment resulted in a significant decrease of the crystallinity (-25%, P< 0.05) and of the hydroxyproline-to-proline ratio (-30%, P<0.05) in newly-formed bones. Moreover, with the high ZA treatment, the crystallinity was positively correlated with the hydroxyproline-to-proline ratio (ρ=0.78, P<0.0001). The present data highlight new properties for ZA on bone formation in a craniofacial defect model. As such, ZA at high doses disrupted the apatite crystal organization. In addition, we report here for the first time that high ZA doses decreased the hydroxyproline-to-proline ratio suggesting that ZA may affect the early collagen organization during the bone healing. Copyright © 2016 Elsevier Inc. All rights reserved.

Space-Time Dependent Transport, Activation, and Dose Rates for Radioactivated Fluids.

NASA Astrophysics Data System (ADS)

Gavazza, Sergio

Two methods are developed to calculate the space - and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates generated from the radioactivated fluids flowing through pipes. The work couples space- and time-dependent phenomena, treated as only space- or time-dependent in the open literature. The transport and activation methodology (TAM) is used to numerically calculate space- and time-dependent transport and activation of radionuclides in fluids flowing through pipes exposed to radiation fields, and volumetric radioactive sources created by radionuclide motions. The computer program Radionuclide Activation and Transport in Pipe (RNATPA1) performs the numerical calculations required in TAM. The gamma ray dose methodology (GAM) is used to numerically calculate space- and time-dependent gamma ray dose equivalent rates from the volumetric radioactive sources determined by TAM. The computer program Gamma Ray Dose Equivalent Rate (GRDOSER) performs the numerical calculations required in GAM. The scope of conditions considered by TAM and GAM herein include (a) laminar flow in straight pipe, (b)recirculating flow schemes, (c) time-independent fluid velocity distributions, (d) space-dependent monoenergetic neutron flux distribution, (e) space- and time-dependent activation process of a single parent nuclide and transport and decay of a single daughter radionuclide, and (f) assessment of space- and time-dependent gamma ray dose rates, outside the pipe, generated by the space- and time-dependent source term distributions inside of it. The methodologies, however, can be easily extended to include all the situations of interest for solving the phenomena addressed in this dissertation. A comparison is made from results obtained by the described calculational procedures with analytical expressions. The physics of the problems addressed by the new technique and the increased accuracy versus non -space and time-dependent methods are presented. The value of the methods is also discussed. It has been demonstrated that TAM and GAM can be used to enhance the understanding of the space- and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates related to radioactivated fluids flowing through pipes.

The Evaluation of the 0.07 and 3 mm Dose Equivalent with a Portable Beta Spectrometer

NASA Astrophysics Data System (ADS)

Hoshi, Katsuya; Yoshida, Tadayoshi; Tsujimura, Norio; Okada, Kazuhiko

Beta spectra of various nuclide species were measured using a commercially available compact spectrometer. The shape of the spectra obtained via the spectrometer was almost similar to that of the theoretical spectra. The beta dose equivalent at any depth was obtained as a product of the measured pulse height spectra and the appropriate conversion coefficients of ICRP Publication 74. The dose rates evaluated from the spectra were comparable with the reference dose rates of standard beta calibration sources. In addition, we were able to determine the dose equivalents with a relative error of indication of 10% without the need for complicated correction.

Ambient Dose Equivalent in S. Paulo and Bauru cities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umisedo, Nancy K.; Okuno, Emico; Cancio, Francisco S.

2008-08-07

The Laboratory of Dosimetry (Institute of Physics, University of S. Paulo) performs since 1981 the external individual monitoring of workers exposed to X and gamma rays based on thermoluminescent dosimetry (TLD). Personal dose equivalent refers only to the exposure of workers due to the working activities, and the dose due to background radiation, also measured with TLD, must be subtracted to evaluate it. A compilation of ambient dose equivalent was done to evaluate the dose due to the background radiation in the work places, and also to contribute to the knowledge of the level of indoor radiation to which themore » public is exposed.« less

Intraoperative Methadone in Same-Day Ambulatory Surgery: A Randomized, Double-Blinded, Dose-Finding Pilot Study.

PubMed

Komen, Helga; Brunt, L Michael; Deych, Elena; Blood, Jane; Kharasch, Evan D

2018-05-25

Approximately 50 million US patients undergo ambulatory surgery annually. Postoperative opioid overprescribing is problematic, yet many patients report inadequate pain relief. In major inpatient surgery, intraoperative single-dose methadone produces better analgesia and reduces opioid use compared with conventional repeated dosing of short-duration opioids. This investigation tested the hypothesis that in same-day ambulatory surgery, intraoperative methadone, compared with short-duration opioids, reduces opioid consumption and pain, and determined an effective intraoperative induction dose of methadone for same-day ambulatory surgery. A double-blind, dose-escalation protocol randomized 60 patients (2:1) to intraoperative single-dose intravenous methadone (initially 0.1 then 0.15 mg/kg ideal body weight) or conventional as-needed dosing of short-duration opioids (eg, fentanyl, hydromorphone; controls). Intraoperative and postoperative opioid consumption, pain, and opioid side effects were assessed before discharge. Patient home diaries recorded pain, opioid use, and opioid side effects daily for 30 days postoperatively. Primary outcome was in-hospital (intraoperative and postoperative) opioid use. Secondary outcomes were 30 days opioid consumption, pain intensity, and opioid side effects. Median (interquartile range) methadone doses were 6 (5-6) and 9 (8-9) mg in the 0.1 and 0.15 mg/kg methadone groups, respectively. Total opioid consumption (morphine equivalents) in the postanesthesia care unit was significantly less compared with controls (9.3 mg, 1.3-11.0) in subjects receiving 0.15 mg/kg methadone (0.1 mg, 0.1-3.3; P < .001) but not 0.1 mg/kg methadone (5.0 mg, 3.3-8.1; P = .60). Dose-escalation ended at 0.15 mg/kg methadone. Total in-hospital nonmethadone opioid use after short-duration opioid, 0.1 mg/kg methadone, and 0.15 mg/kg methadone was 35.3 (25.0-44.0), 7.1 (3.7-10.0), and 3.3 (0.1-5.8) mg morphine equivalents, respectively (P < .001 for both versus control). In-hospital pain scores and side effects were not different between groups. In the 30 days after discharge, patients who received methadone 0.15 mg/kg had less pain at rest (P = .02) and used fewer opioid pills than controls (P < .0001), whereas patients who received 0.1 mg/kg had no difference in pain at rest (P = .69) and opioid use compared to controls (P = .08). In same-day discharge surgery, this pilot study identified a single intraoperative dose of methadone (0.15 mg/kg ideal body weight), which decreased intraoperative and postoperative opioid requirements and postoperative pain, compared with conventional intermittent short-duration opioids, with similar side effects.

A MULTI-ELEMENT THICK GAS ELECTRON MULTIPLIER-BASED MICRODOSEMETER FOR MEASUREMENT OF NEUTRONS DOSE-EQUIVALENT: A MONTE CARLO STUDY.

PubMed

Moslehi, A; Raisali, G

2017-11-01

To determine the dose-equivalent of neutrons in an extended energy range, in the present work a multi-element thick gas electron multiplier-based microdosemeter made of PMMA (Perspex) walls of 10 mm in thickness is designed. Each cavity is filled with the propane-based tissue-equivalent (TE) gas simulating 1 µm of tissue. Also, a few weight fractions of 3He are assumed to be added to the TE gas. The dose-equivalents are determined for 11 neutron energies between thermal and 14 MeV using the lineal energy distributions calculated by Geant4 simulation toolkit and also the lineal energy-based quality factors. The results show that by adding 0.04% of 3He to the TE gas in each cavity, an energy-independent dose-equivalent response within 30% uncertainty around a median value of 0.91 in the above energy range is achieved. It is concluded that after its construction, the studied microdosemeter can be used to measure the dose-equivalent of neutrons, favorably. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Shielding application of perturbation theory to determine changes in neutron and gamma doses due to changes in shield layers

NASA Technical Reports Server (NTRS)

Fieno, D.

1972-01-01

Perturbation theory formulas were derived and applied to determine changes in neutron and gamma-ray doses due to changes in various radiation shield layers for fixed sources. For a given source and detector position, the perturbation method enables dose derivatives with respect to density, or equivalently thickness, for every layer to be determined from one forward and one inhomogeneous adjoint calculation. A direct determination without the perturbation approach would require two forward calculations to evaluate the dose derivative due to a change in a single layer. Hence, the perturbation method for obtaining dose derivatives requires fewer computations for design studies of multilayer shields. For an illustrative problem, a comparison was made of the fractional change in the dose per unit change in the thickness of each shield layer in a two-layer spherical configuration as calculated by perturbation theory and by successive direct calculations; excellent agreement was obtained between the two methods.

ORANGE: a Monte Carlo dose engine for radiotherapy.

PubMed

van der Zee, W; Hogenbirk, A; van der Marck, S C

2005-02-21

This study presents data for the verification of ORANGE, a fast MCNP-based dose engine for radiotherapy treatment planning. In order to verify the new algorithm, it has been benchmarked against DOSXYZ and against measurements. For the benchmarking, first calculations have been done using the ICCR-XIII benchmark. Next, calculations have been done with DOSXYZ and ORANGE in five different phantoms (one homogeneous, two with bone equivalent inserts and two with lung equivalent inserts). The calculations have been done with two mono-energetic photon beams (2 MeV and 6 MeV) and two mono-energetic electron beams (10 MeV and 20 MeV). Comparison of the calculated data (from DOSXYZ and ORANGE) against measurements was possible for a realistic 10 MV photon beam and a realistic 15 MeV electron beam in a homogeneous phantom only. For the comparison of the calculated dose distributions and dose distributions against measurements, the concept of the confidence limit (CL) has been used. This concept reduces the difference between two data sets to a single number, which gives the deviation for 90% of the dose distributions. Using this concept, it was found that ORANGE was always within the statistical bandwidth with DOSXYZ and the measurements. The ICCR-XIII benchmark showed that ORANGE is seven times faster than DOSXYZ, a result comparable with other accelerated Monte Carlo dose systems when no variance reduction is used. As shown for XVMC, using variance reduction techniques has the potential for further acceleration. Using modern computer hardware, this brings the total calculation time for a dose distribution with 1.5% (statistical) accuracy within the clinical range (less then 10 min). This means that ORANGE can be a candidate for a dose engine in radiotherapy treatment planning.

Choice of antibiotics for infection prophylaxis in emergency cesarean sections in low-income countries: a cost-benefit study in Mozambique.

PubMed

Kayihura, Vicente; Osman, Nafissa Bique; Bugalho, Antonio; Bergström, Staffan

2003-07-01

There is a need to assess the cost-benefit of different models of antibiotic administration for the prevention of post cesarean infection, particularly in resource-scarce settings. Randomized, nonblinded comparative study of a single combined preoperative dose of gentamicin and metronidazole vs. a post cesarean scheme for infection prophylaxis. Pregnant women (n = 288) with indication for emergency cesarean section were randomly allotted to two groups. Group 1 (n = 143) received the single, combined dose of prophylactic antibiotics and group 2 (n = 145) received, over 7 days, the postoperative standard scheme of antibiotics followed in the department. Both groups were followed up during 7 days for detection of signs of wound infection, endometritis, peritonitis and urinary tract infection. Prevalence of postoperative infection, mean hospital stay and costs of antibiotics used. Women completing the study (n = 241) were distributed into group 1 (n = 116) and group 2 (n = 125). No significant difference was found neither in the prevalence of postoperative infection nor in the mean hospital stay. No death occurred. The cost of the single dose of prophylactic antibiotics was less than one-tenth of the cost of the standard postoperative scheme. In our setting, the administration of a single dose of 160 mg of gentamicin in combination with 500 mg of metronidazole before emergency cesarean section for prevention of infection is clinically equivalent to existing conventional week-long postoperative therapy, but at approximately one-tenth of the cost.

Shielding implications for secondary neutrons and photons produced within the patient during IMPT.

PubMed

DeMarco, J; Kupelian, P; Santhanam, A; Low, D

2013-07-01

Intensity modulated proton therapy (IMPT) uses a combination of computer controlled spot scanning and spot-weight optimized planning to irradiate the tumor volume uniformly. In contrast to passive scattering systems, secondary neutrons and photons produced from inelastic proton interactions within the patient represent the major source of emitted radiation during IMPT delivery. Various published studies evaluated the shielding considerations for passive scattering systems but did not directly address secondary neutron production from IMPT and the ambient dose equivalent on surrounding occupational and nonoccupational work areas. Thus, the purpose of this study was to utilize Monte Carlo simulations to evaluate the energy and angular distributions of secondary neutrons and photons following inelastic proton interactions within a tissue-equivalent phantom for incident proton spot energies between 70 and 250 MeV. Monte Carlo simulation methods were used to calculate the ambient dose equivalent of secondary neutrons and photons produced from inelastic proton interactions in a tissue-equivalent phantom. The angular distribution of emitted neutrons and photons were scored as a function of incident proton energy throughout a spherical annulus at 1, 2, 3, 4, and 5 m from the phantom center. Appropriate dose equivalent conversion factors were applied to estimate the total ambient dose equivalent from secondary neutrons and photons. A reference distance of 1 m from the center of the patient was used to evaluate the mean energy distribution of secondary neutrons and photons and the resulting ambient dose equivalent. For an incident proton spot energy of 250 MeV, the total ambient dose equivalent (3.6 × 10(-3) mSv per proton Gy) was greatest along the direction of the incident proton spot (0°-10°) with a mean secondary neutron energy of 71.3 MeV. The dose equivalent decreased by a factor of 5 in the backward direction (170°-180°) with a mean energy of 4.4 MeV. An 8 × 8 × 8 cm(3) volumetric spot distribution (5 mm FWHM spot size, 4 mm spot spacing) optimized to produce a uniform dose distribution results in an ambient dose equivalent of 4.5 × 10(-2) mSv per proton Gy in the forward direction. This work evaluated the secondary neutron and photon emission due to monoenergetic proton spots between 70 and 250 MeV, incident on a tissue equivalent phantom. Example calculations were performed to estimate concrete shield thickness based upon appropriate workload and shielding design assumptions. Although lower than traditional passive scattered proton therapy systems, the ambient dose equivalent from secondary neutrons produced by the patient during IMPT can be significant relative to occupational and nonoccupational workers in the vicinity of the treatment vault. This work demonstrates that Monte Carlo simulations are useful as an initial planning tool for studying the impact of the treatment room and maze design on surrounding occupational and nonoccupational work areas.

Assessment of physician and patient (child and adult) equivalent doses during renal angiography by Monte Carlo method.

PubMed

Karimian, A; Nikparvar, B; Jabbari, I

2014-11-01

Renal angiography is one of the medical imaging methods in which patient and physician receive high equivalent doses due to long duration of fluoroscopy. In this research, equivalent doses of some radiosensitive tissues of patient (adult and child) and physician during renal angiography have been calculated by using adult and child Oak Ridge National Laboratory phantoms and Monte Carlo method (MCNPX). The results showed, in angiography of right kidney in a child and adult patient, that gall bladder with the amounts of 2.32 and 0.35 mSv, respectively, has received the most equivalent dose. About the physician, left hand, left eye and thymus absorbed the most amounts of doses, means 0.020 mSv. In addition, equivalent doses of the physician's lens eye, thyroid and knees were 0.023, 0.007 and 7.9E-4 mSv, respectively. Although these values are less than the reported thresholds by ICRP 103, it should be noted that these amounts are related to one examination. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Experimental verification of a commercial Monte Carlo-based dose calculation module for high-energy photon beams.

PubMed

Künzler, Thomas; Fotina, Irina; Stock, Markus; Georg, Dietmar

2009-12-21

The dosimetric performance of a Monte Carlo algorithm as implemented in a commercial treatment planning system (iPlan, BrainLAB) was investigated. After commissioning and basic beam data tests in homogenous phantoms, a variety of single regular beams and clinical field arrangements were tested in heterogeneous conditions (conformal therapy, arc therapy and intensity-modulated radiotherapy including simultaneous integrated boosts). More specifically, a cork phantom containing a concave-shaped target was designed to challenge the Monte Carlo algorithm in more complex treatment cases. All test irradiations were performed on an Elekta linac providing 6, 10 and 18 MV photon beams. Absolute and relative dose measurements were performed with ion chambers and near tissue equivalent radiochromic films which were placed within a transverse plane of the cork phantom. For simple fields, a 1D gamma (gamma) procedure with a 2% dose difference and a 2 mm distance to agreement (DTA) was applied to depth dose curves, as well as to inplane and crossplane profiles. The average gamma value was 0.21 for all energies of simple test cases. For depth dose curves in asymmetric beams similar gamma results as for symmetric beams were obtained. Simple regular fields showed excellent absolute dosimetric agreement to measurement values with a dose difference of 0.1% +/- 0.9% (1 standard deviation) at the dose prescription point. A more detailed analysis at tissue interfaces revealed dose discrepancies of 2.9% for an 18 MV energy 10 x 10 cm(2) field at the first density interface from tissue to lung equivalent material. Small fields (2 x 2 cm(2)) have their largest discrepancy in the re-build-up at the second interface (from lung to tissue equivalent material), with a local dose difference of about 9% and a DTA of 1.1 mm for 18 MV. Conformal field arrangements, arc therapy, as well as IMRT beams and simultaneous integrated boosts were in good agreement with absolute dose measurements in the heterogeneous phantom. For the clinical test cases, the average dose discrepancy was 0.5% +/- 1.1%. Relative dose investigations of the transverse plane for clinical beam arrangements were performed with a 2D gamma-evaluation procedure. For 3% dose difference and 3 mm DTA criteria, the average value for gamma(>1) was 4.7% +/- 3.7%, the average gamma(1%) value was 1.19 +/- 0.16 and the mean 2D gamma-value was 0.44 +/- 0.07 in the heterogeneous phantom. The iPlan MC algorithm leads to accurate dosimetric results under clinical test conditions.

Bolus dose response characteristics of single chain urokinase plasminogen activator and tissue plasminogen activator in a dog model of arterial thrombosis.

PubMed

Badylak, S F; Voytik, S; Klabunde, R E; Henkin, J; Leski, M

1988-11-15

Tissue plasminogen activator (t-PA) and single chain urokinase-plasminogen activator (scu-PA) are relatively "fibrin-specific" thrombolytic drugs with short plasma half lives of 6-8 minutes. Most treatment regimens with these agents utilize a bolus injection followed by continuous drug infusion, usually combined with anticoagulant therapy. The purpose of this study was to establish the dose-response characteristics for scu-PA and t-PA, when given as a single intravenous bolus injection, in a dog model of arterial thrombosis. Eight groups of 6 dogs each were given one of the following doses of scu-PA (mg/kg): 0.20, 0.50, 1.00, 2.00; or t-PA: 0.05, 0.10, 0.20; or an equivalent amount of saline (control group). All doses were given as a single bolus injection 60 minutes after formation of a totally occlusive femoral artery thrombus. Thrombolysis was measured by monitoring the continuous decrement of 125I activity from a radiolabelled thrombus. Ninety minutes after drug injection, all scu-PA treated dogs showed greater thrombolysis (30%, 45%, 56%, and 67%, respectively) than the control group (15%, p less than 0.01). The 0.10 and 0.20 mg/kg t-PA treated dogs showed greater thrombolysis (35% and 49%, respectively) than the control group (15%, p less than 0.01). Both scu-PA and t-PA caused a partial and dose-dependent decrease in alpha 2-antiplasmin activity but scu-PA caused a greater depletion (72% vs. 18%, respectively, p less than 0.05) at 60 minutes after the highest dose of drug administration. Both drugs showed a longer than expected thrombolytic effect based upon the known half lives. Neither drug caused significant changes in the prothrombin time, activated partial thromboplastin time, thrombin time, hematocrit, platelet count, or fibrin degradation product concentration. Single bolus injections of scu-PA and t-PA produce safe and effective thrombolysis in this dog model of arterial thrombosis.

Computational analysis of the dose rates at JSI TRIGA reactor irradiation facilities.

PubMed

Ambrožič, K; Žerovnik, G; Snoj, L

2017-12-01

The JSI TRIGA Mark II, IJS research reactor is equipped with numerous irradiation positions, where samples can be irradiated by neutrons and γ-rays. Irradiation position selection is based on its properties, such as physical size and accessibility, as well as neutron and γ-ray spectra, flux and dose intensities. This paper presents an overview on the neutron and γ-ray fluxes, spectra and dose intensities calculations using Monte Carlo MCNP software and ENDF/B-VII.0 nuclear data libraries. The dose-rates are presented in terms of ambient dose equivalents, air kerma, and silicon dose equivalent. At full reactor power the neutron ambient dose equivalent ranges from 5.5×10 3 Svh -1 to 6×10 6 Svh -1 , silicon dose equivalent from 6×10 2 Gy/h si to 3×10 5 Gy/h si , and neutron air kerma from 4.3×10 3 Gyh -1 to 2×10 5 Gyh -1 . Ratio of fast (1MeV

Estimation of neutron dose equivalent at the mezzanine of the Advanced Light Source and the laboratory boundary using the ORNL program MORSE.

PubMed

Sun, R K

1990-12-01

To investigate the radiation effect of neutrons near the Advanced Light Source (ALS) at Lawrence Berkeley Laboratory (LBL) with respect to the neutron dose equivalents in nearby occupied areas and at the site boundary, the neutron transport code MORSE, from Oak Ridge National Laboratory (ORNL), was used. These dose equivalents result from both skyshine neutrons transported by air scattering and direct neutrons penetrating the shielding. The ALS neutron sources are a 50-MeV linear accelerator and its transfer line, a 1.5-GeV booster, a beam extraction line, and a 1.9-GeV storage ring. The most conservative total occupational-dose-equivalent rate in the center of the ALS mezzanine, 39 m from the ALS center, was found to be 1.14 X 10(-3) Sv y-1 per 2000-h "occupational" year, and the total environmental-dose-equivalent rate at the ALS boundary, 125 m from the ALS center, was found to be 3.02 X 10(-4) Sv y-1 per 8760-h calendar year. More realistic dose-equivalent rates, using the nominal (expected) storage-ring current, were calculated to be 1.0 X 10(-4) Sv y-1 and 2.65 X 10(-5) Sv y-1 occupational year and calendar year, respectively, which are much lower than the DOE reporting levels.

Clinical Pharmacokinetics and Safety of ALZ-801, a Novel Prodrug of Tramiprosate in Development for the Treatment of Alzheimer's Disease.

PubMed

Hey, John A; Yu, Jeremy Y; Versavel, Mark; Abushakra, Susan; Kocis, Petr; Power, Aidan; Kaplan, Paul L; Amedio, John; Tolar, Martin

2018-03-01

ALZ-801 is an orally available, valine-conjugated prodrug of tramiprosate. Tramiprosate, the active agent, is a small-molecule β-amyloid (Aβ) anti-oligomer and aggregation inhibitor that was evaluated extensively in preclinical and clinical investigations for the treatment of Alzheimer's disease (AD). Tramiprosate has been found to inhibit β-amyloid oligomer formation by a multi-ligand enveloping mechanism of action that stabilizes Aβ42 monomers, resulting in the inhibition of formation of oligomers and subsequent aggregation. Although promising as an AD treatment, tramiprosate exhibited two limiting deficiencies: high intersubject pharmacokinetic (PK) variability likely due to extensive gastrointestinal metabolism, and mild-to-moderate incidence of nausea and vomiting. To address these, we developed an optimized prodrug, ALZ-801, which retains the favorable efficacy attributes of tramiprosate while improving oral PK variability and gastrointestinal tolerability. In this study, we summarize the phase I bridging program to evaluate the safety, tolerability and PK for ALZ-801 after single and multiple rising dose administration in healthy volunteers. Randomized, placebo-controlled, phase I studies in 127 healthy male and female adult and elderly volunteers included [1] a single ascending dose (SAD) study; [2] a 14-day multiple ascending dose (MAD) study; and [3] a single-dose tablet food-effect study. This program was conducted with both a loose-filled capsule and an immediate-release tablet formulation, under both fasted and fed conditions. Safety and tolerability were assessed, and plasma and urine were collected for liquid chromatography-mass spectrometry (LC-MS) determination and non-compartmental PK analysis. In addition, we defined the target dose of ALZ-801 that delivers a steady-state plasma area under the curve (AUC) exposure of tramiprosate equivalent to that studied in the tramiprosate phase III study. ALZ-801 was well tolerated and there were no severe or serious adverse events (AEs) or laboratory findings. The most common AEs were transient mild nausea and some instances of vomiting, which were not dose-related and showed development of tolerance after continued use. ALZ-801 produced dose-dependent maximum plasma concentration (C max ) and AUC exposures of tramiprosate, which were equivalent to that after oral tramiprosate, but with a substantially reduced intersubject variability and a longer elimination half-life. Administration of ALZ-801 with food markedly reduced the incidence of gastrointestinal symptoms compared with the fasted state, without affecting plasma tramiprosate exposure. An immediate-release tablet formulation of ALZ-801 displayed plasma exposure and low variability similar to the loose-filled capsule. ALZ-801 also showed excellent dose-proportionality without accumulation or decrease in plasma exposure of tramiprosate over 14 days. Based on these data, 265 mg of ALZ-801 twice daily was found to achieve a steady-state AUC exposure of tramiprosate equivalent to 150 mg twice daily of oral tramiprosate in the previous phase III trials. ALZ-801, when administered in capsule and tablet forms, showed excellent oral safety and tolerability in healthy adults and elderly volunteers, with significantly improved PK characteristics over oral tramiprosate. A clinical dose of ALZ-801 (265 mg twice daily) was established that achieves the AUC exposure of 150 mg of tramiprosate twice daily, which showed positive cognitive and functional improvements in apolipoprotein E4/4 homozygous AD patients. These bridging data support the phase III development of ALZ-801in patients with AD.

Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures

NASA Astrophysics Data System (ADS)

Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Porto, L. E.; Ledesma, J. A.; Nascimento, E. X.; Legnani, A.; Andrade, M. E. A.; Khoury, H. J.

2015-11-01

This study investigates patient and staff dose measurements in pediatric barium meal series fluoroscopic procedures. It aims to analyze radiographic techniques, measure the air kerma-area product (PKA), and estimate the staff's eye lens, thyroid and hands equivalent doses. The procedures of 41 patients were studied, and PKA values were calculated using LiF:Mg,Ti thermoluminescent dosimeters (TLDs) positioned at the center of the patient's upper chest. Furthermore, LiF:Mg,Cu,P TLDs were used to estimate the equivalent doses. The results showed a discrepancy in the radiographic techniques when compared to the European Commission recommendations. Half of the results of the analyzed literature presented lower PKA and dose reference level values than the present study. The staff's equivalent doses strongly depends on the distance from the beam. A 55-cm distance can be considered satisfactory. However, a distance decrease of ~20% leads to, at least, two times higher equivalent doses. For eye lenses this dose is significantly greater than the annual limit set by the International Commission on Radiological Protection. In addition, the occupational doses were found to be much higher than in the literature. Changing the used radiographic techniques to the ones recommended by the European Communities, it is expected to achieve lower PKA values ​​and occupational doses.

Measurement of the secondary neutron dose distribution from the LET spectrum of recoils using the CR-39 plastic nuclear track detector in 10 MV X-ray medical radiation fields

NASA Astrophysics Data System (ADS)

Fujibuchi, Toshioh; Kodaira, Satoshi; Sawaguchi, Fumiya; Abe, Yasuyuki; Obara, Satoshi; Yamaguchi, Masae; Kawashima, Hajime; Kitamura, Hisashi; Kurano, Mieko; Uchihori, Yukio; Yasuda, Nakahiro; Koguchi, Yasuhiro; Nakajima, Masaru; Kitamura, Nozomi; Sato, Tomoharu

2015-04-01

We measured the recoil charged particles from secondary neutrons produced by the photonuclear reaction in a water phantom from a 10-MV photon beam from medical linacs. The absorbed dose and the dose equivalent were evaluated from the linear energy transfer (LET) spectrum of recoils using the CR-39 plastic nuclear track detector (PNTD) based on well-established methods in the field of space radiation dosimetry. The contributions and spatial distributions of these in the phantom on nominal photon exposures were verified as the secondary neutron dose and neutron dose equivalent. The neutron dose equivalent normalized to the photon-absorbed dose was 0.261 mSv/100 MU at source to chamber distance 90 cm. The dose equivalent at the surface gave the highest value, and was attenuated to less than 10% at 5 cm from the surface. The dose contribution of the high LET component of ⩾100 keV/μm increased with the depth in water, resulting in an increase of the quality factor. The CR-39 PNTD is a powerful tool that can be used to systematically measure secondary neutron dose distributions in a water phantom from an in-field to out-of-field high-intensity photon beam.

Randomized clinical trial to comparing efficacy of daily, weekly and monthly administration of vitamin D3.

PubMed

Takács, István; Tóth, Béla E; Szekeres, László; Szabó, Boglárka; Bakos, Bence; Lakatos, Péter

2017-01-01

The comparative efficacy and safety profiles of selected daily 1000 IU, weekly 7000 IU and monthly 30,000 IU vitamin D 3 -not previously investigated-will be evaluated. Here, a prospective, randomized clinical trial, comparing efficacy and safety of a daily single dose of 1000 IU (group A) to a once-weekly 7000 IU dose (group B), or monthly 30,000 IU dose (group C) of vitamin D 3 . The present study is a controlled, randomized, open-label, multicenter clinical trial, 3  months in duration. Sixty-four adult subjects with vitamin D deficiency (25OHD<20 ng/ml), were included according to the inclusion and exclusion criteria. Dose-responses for increases in serum vitamin 25OHD were statistically equivalent for each of the three groups: A, B and C. Outcomes were 13.0 ± 1.5; 12.6 ± 1.1 and 12.9 ± 0.9 ng/ml increases in serum 25OHD per 1000 IU, daily, weekly and monthly, respectively. The treatment of subjects with selected doses restored 25OHD values to levels above 20 ng/ml in all groups. Treatment with distinct administration frequency of vitamin D 3 did not exhibit any differences in safety parameters. The daily, weekly and monthly administrations of daily equivalent of 1000 IU of vitamin D 3 provide equal efficacy and safety profiles.

“One pill, once daily”: what clinicians need to know about Atripla™

PubMed Central

Clay, Patrick G; Taylor, Tracey AH; Glaros, Alan G; McRae, MaryPeace; Williams, Charlott; McCandless, Don; Oelklaus, Maurice

2008-01-01

As the number of persons chronically prescribed antiretrovirals has grown and the realization that antiretrovirals are required to be continued for life, pharmaceutical manufacturers have developed new classes of agents, improved the pharmacokinetics of marketed products through dosing reformulations, and in an effort to maximize success with respect to adherence, compiled into a single dosing unit all necessary elements for an antiretroviral regimen. Atripla™ represents the first ever fixed-dose combination antiretroviral available. This article reviews currently available data on this agent, the impact of resistance on clinical use and implementation, as well as extensive descriptions of the pharmacokinetics, adverse effects and drug-interactions warranting consideration. Whether beginning in a naïve patient or switching from other regimens for tolerability issues, Atripla™ represents a viable option. Its demonstrated advantages with respect to lipid and hematologic parameters and equivalent incidence of renal toxicity are tempered by the findings of bone mineral density decreases, however. Combining multiple mechanisms of action in a single dosing unit appears to improve efficacy, increase the likelihood for adherence and maintain viral suppression compared to administering these agents independently. It is suggested other pharmaceutical companies assess the potential to replicate this for the remaining antiretrovirals. PMID:18728842

Water and tissue equivalence of a new PRESAGE{sup Registered-Sign} formulation for 3D proton beam dosimetry: A Monte Carlo study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gorjiara, Tina; Kuncic, Zdenka; Doran, Simon

2012-11-15

Purpose: To evaluate the water and tissue equivalence of a new PRESAGE{sup Registered-Sign} 3D dosimeter for proton therapy. Methods: The GEANT4 software toolkit was used to calculate and compare total dose delivered by a proton beam with mean energy 62 MeV in a PRESAGE{sup Registered-Sign} dosimeter, water, and soft tissue. The dose delivered by primary protons and secondary particles was calculated. Depth-dose profiles and isodose contours of deposited energy were compared for the materials of interest. Results: The proton beam range was found to be Almost-Equal-To 27 mm for PRESAGE{sup Registered-Sign }, 29.9 mm for soft tissue, and 30.5 mmmore » for water. This can be attributed to the lower collisional stopping power of water compared to soft tissue and PRESAGE{sup Registered-Sign }. The difference between total dose delivered in PRESAGE{sup Registered-Sign} and total dose delivered in water or tissue is less than 2% across the entire water/tissue equivalent range of the proton beam. The largest difference between total dose in PRESAGE{sup Registered-Sign} and total dose in water is 1.4%, while for soft tissue it is 1.8%. In both cases, this occurs at the distal end of the beam. Nevertheless, the authors find that PRESAGE{sup Registered-Sign} dosimeter is overall more tissue-equivalent than water-equivalent before the Bragg peak. After the Bragg peak, the differences in the depth doses are found to be due to differences in primary proton energy deposition; PRESAGE{sup Registered-Sign} and soft tissue stop protons more rapidly than water. The dose delivered by secondary electrons in the PRESAGE{sup Registered-Sign} differs by less than 1% from that in soft tissue and water. The contribution of secondary particles to the total dose is less than 4% for electrons and Almost-Equal-To 1% for protons in all the materials of interest. Conclusions: These results demonstrate that the new PRESAGE{sup Registered-Sign} formula may be considered both a tissue- and water-equivalent 3D dosimeter for a 62 MeV proton beam. The results further suggest that tissue-equivalent thickness may provide better dosimetric and geometric accuracy than water-equivalent thickness for 3D dosimetry of this proton beam.« less

Towards tracer dose reduction in PET studies: Simulation of dose reduction by retrospective randomized undersampling of list-mode data.

PubMed

Gatidis, Sergios; Würslin, Christian; Seith, Ferdinand; Schäfer, Jürgen F; la Fougère, Christian; Nikolaou, Konstantin; Schwenzer, Nina F; Schmidt, Holger

2016-01-01

Optimization of tracer dose regimes in positron emission tomography (PET) imaging is a trade-off between diagnostic image quality and radiation exposure. The challenge lies in defining minimal tracer doses that still result in sufficient diagnostic image quality. In order to find such minimal doses, it would be useful to simulate tracer dose reduction as this would enable to study the effects of tracer dose reduction on image quality in single patients without repeated injections of different amounts of tracer. The aim of our study was to introduce and validate a method for simulation of low-dose PET images enabling direct comparison of different tracer doses in single patients and under constant influencing factors. (18)F-fluoride PET data were acquired on a combined PET/magnetic resonance imaging (MRI) scanner. PET data were stored together with the temporal information of the occurrence of single events (list-mode format). A predefined proportion of PET events were then randomly deleted resulting in undersampled PET data. These data sets were subsequently reconstructed resulting in simulated low-dose PET images (retrospective undersampling of list-mode data). This approach was validated in phantom experiments by visual inspection and by comparison of PET quality metrics contrast recovery coefficient (CRC), background-variability (BV) and signal-to-noise ratio (SNR) of measured and simulated PET images for different activity concentrations. In addition, reduced-dose PET images of a clinical (18)F-FDG PET dataset were simulated using the proposed approach. (18)F-PET image quality degraded with decreasing activity concentrations with comparable visual image characteristics in measured and in corresponding simulated PET images. This result was confirmed by quantification of image quality metrics. CRC, SNR and BV showed concordant behavior with decreasing activity concentrations for measured and for corresponding simulated PET images. Simulation of dose-reduced datasets based on clinical (18)F-FDG PET data demonstrated the clinical applicability of the proposed data. Simulation of PET tracer dose reduction is possible with retrospective undersampling of list-mode data. Resulting simulated low-dose images have equivalent characteristics with PET images actually measured at lower doses and can be used to derive optimal tracer dose regimes.

Monomeric DR2/MOG-35-55 recombinant TCR ligand treats relapses of experimental encephalomyelitis in DR2 transgenic mice.

PubMed

Link, Jason M; Rich, Cathleen M; Korat, Maya; Burrows, Gregory G; Offner, Halina; Vandenbark, Arthur A

2007-04-01

Treatment of human autoimmune diseases such as multiple sclerosis (MS) will likely require agents that can prevent or reverse the inflammatory process that results in clinical relapses and disease progression. We evaluated the ability of a newly designed monomeric recombinant TCR ligand (RTL342M) containing HLA-DR2 peptide-binding domains covalently linked to MOG-35-55 peptide to prevent and treat both the initial episode and subsequent relapses of experimental autoimmune encephalomyelitis (EAE) in HLA-DR2 transgenic mice. Single doses of RTL342M given either i.v. or s.c. to HLA-DR2 mice produced a rapid (within 24 h) and dose-dependent reversal of clinical signs of paralytic EAE, and even a single dose < or = 2 microg could produce a significant treatment effect. Multiple daily doses were even more effective than the same total amount of RTL given as a single dose. By establishing the minimal effective dose, we determined that RTLs may be 50 times more potent than molar equivalent doses of myelin peptide alone. RTL342M given prior to induction of EAE prevented disease in most mice, and the remainder could be successfully retreated with RTL. Most important for clinical application, RTL342M was highly effective for treating EAE relapses when given periodically prior to the relapse or even after relapses had occurred. These data demonstrate the rapid and potent clinical effects of RTL342M at disease onset and during relapses in EAE and establish important principles governing the application of this novel approach as a possible therapy for patients with MS.

[Antihypoxic effect of 3-hydroxypyridine and succinic acid derivatives and their nootropic action in alloxan diabetes].

PubMed

Volchegorskiĭ, I A; Rassokhina, L M; Miroshnichenko, I Iu

2011-01-01

Relationship between the antihypoxic effect of 3-hydroxypyridine and succinic acid derivatives (emoxipine, reamberin and mexidol) and their effect on conditional learning, glycemia, and lipidemia was studied in rats with alloxan-induced diabetes. In parallel, the analogous relationship was investigated for alpha-lipoic acid that is regarded as a "gold standard" in treatment of diabetic neuropathy. It was established that single administration of emoxipine and mexidol in mice in doses equivalent to therapeutic-range doses in humans produces antihypoxic effect manifested by increased resistance to acute hypoxic hypoxia in test animals. Alpha-lipoic acid is inferior to emoxipin and mexidol in the degree of antihypoxic action. Reamberin does not exhibit this effect. The introduction of emoxipin, reamberin, mexidol, and alpha-lipoic acid in rats with alloxan diabetes during 7 or 14 days in doses equivalent to therapeutic-range doses in humans corrects conditional learning disorders in direct relationship with the antihypoxic activity of these drugs. The development of the nootropic effect of emoxipin, mexidol, and alpha-lipoic acid is related to a decrease in hyperglycemia and hyperlipidemia in rats with alloxan diabetes. The nootropic action of reamberin is accompanied by a transient hypoglycemizing effect and aggravation of dyslipidemic disorders. The antihypoxic activity of investigated drugs determines the direction and expression of their lipidemic effect, but is not correlated with the hypoglycemizing action these drugs on test animals with alloxan diabetes.

Monte Carlo study of out-of-field exposure in carbon-ion radiotherapy with a passive beam: Organ doses in prostate cancer treatment.

PubMed

Yonai, Shunsuke; Matsufuji, Naruhiro; Akahane, Keiichi

2018-04-23

The aim of this work was to estimate typical dose equivalents to out-of-field organs during carbon-ion radiotherapy (CIRT) with a passive beam for prostate cancer treatment. Additionally, sensitivity analyses of organ doses for various beam parameters and phantom sizes were performed. Because the CIRT out-of-field dose depends on the beam parameters, the typical values of those parameters were determined from statistical data on the target properties of patients who received CIRT at the Heavy-Ion Medical Accelerator in Chiba (HIMAC). Using these typical beam-parameter values, out-of-field organ dose equivalents during CIRT for typical prostate treatment were estimated by Monte Carlo simulations using the Particle and Heavy-Ion Transport Code System (PHITS) and the ICRP reference phantom. The results showed that the dose decreased with distance from the target, ranging from 116 mSv in the testes to 7 mSv in the brain. The organ dose equivalents per treatment dose were lower than those either in 6-MV intensity-modulated radiotherapy or in brachytherapy with an Ir-192 source for organs within 40 cm of the target. Sensitivity analyses established that the differences from typical values were within ∼30% for all organs, except the sigmoid colon. The typical out-of-field organ dose equivalents during passive-beam CIRT were shown. The low sensitivity of the dose equivalent in organs farther than 20 cm from the target indicated that individual dose assessments required for retrospective epidemiological studies may be limited to organs around the target in cases of passive-beam CIRT for prostate cancer. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Develop real-time dosimetry concepts and instrumentation for long term missions

NASA Technical Reports Server (NTRS)

Braby, L. A.

1982-01-01

The development of a rugged portable instrument to evaluate dose and dose equivalent is described. A tissue-equivalent proportional counter simulating a 2 micrometer spherical tissue volume was operated satisfactorily for over a year. The basic elements of the electronic system were designed and tested. And finally, the most suitable mathematical technique for evaluating dose equivalent with a portable instrument was selected. Design and fabrication of a portable prototype, based on the previously tested circuits, is underway.

Exposure of the surgeon's hands to radiation during hand surgery procedures.

PubMed

Żyluk, Andrzej; Puchalski, Piotr; Szlosser, Zbigniew; Dec, Paweł; Chrąchol, Joanna

2014-01-01

The objective of the study was to assess the time of exposure of the surgeon's hands to radiation and calculate of the equivalent dose absorbed during surgery of hand and wrist fractures with C-arm fluoroscope guidance. The necessary data specified by the objective of the study were acquired from operations of 287 patients with fractures of fingers, metacarpals, wrist bones and distal radius. 218 operations (78%) were percutaneous procedures and 60 (22%) were performed by open method. Data on the time of exposure and dose of radiation were acquired from the display of the fluoroscope, where they were automatically generated. These data were assigned to the individual patient, type of fracture, method of surgery and the operating surgeon. Fixations of distal radial fractures required longer times of radiation exposure (mean 61 sec.) than fractures of the wrist/metacarpals and fingers (38 and 32 sec., respectively), which was associated with absorption of significantly higher equivalent doses. Fixations of distal radial fractures by open method were associated with statistically significantly higher equivalent doses (0.41 mSv) than percutaneous procedures (0.3 mSv). Fixations of wrist and metacarpal bone fractures by open method were associated with lower equivalent doses (0.34 mSv) than percutaneous procedures (0.37 mSv),but the difference was not significant. Fixations of finger fractures by open method were associated with lower equivalent doses (0.13 mSv) than percutaneous procedures (0.24 mSv), the difference being statistically non-significant. Statistically significant differences in exposure time and equivalent doses were noted between 4 surgeons participating in the study, but no definitive relationship was found between these parameters and surgeons' employment time. 1. Hand surgery procedures under fluoroscopic guidance are associated with mild exposure of the surgeons' hands to radiation. 2. The equivalent dose was related to the type of fracture, operative technique and - to some degree - to the time of employment of the surgeon.

Effect of Vemurafenib on the Pharmacokinetics of a Single Dose of Digoxin in Patients With BRAFV600 Mutation-Positive Metastatic Malignancy.

PubMed

Zhang, Weijiang; McIntyre, Christine; Kuhn, Melissa; Forbes, Harper; Kim, Tae Min; Lee, Jeeyun; Demidov, Lev; Colburn, Dawn

2018-04-12

The primary objective of this phase 1, open-label, multicenter, 3-period, fixed-sequence study was to evaluate the effect of multiple doses of vemurafenib on the pharmacokinetics of a single dose of digoxin, a probe P-glycoprotein (P-gp) substrate, in patients with BRAF V600 mutation-positive metastatic malignancy. Following a 28-day screening period, patients received a single oral dose of digoxin 0.25 mg on day 1 in period A, oral vemurafenib 960 mg twice daily for 21 days in period B (days 8-28), and a single oral dose of digoxin 0.25 mg on day 29 and vemurafenib 960 mg twice a day for 7 days (days 29-35) in period C. Log-transformed area under the concentration-time curve and peak concentration values for digoxin were compared between periods A (digoxin alone) and C (digoxin + vemurafenib) using an analysis of variance model. Twenty-six patients were evaluated for the primary pharmacokinetic analysis. The geometric mean ratio (period C/period A) of area under the curve to the last measurable concentration for digoxin was 1.82 (90%CI 1.63 to 2.02), and the geometric mean ratio of peak concentrations was 1.47 (90%CI 1.30 to 1.65); the 90%CIs were outside of the equivalence limits of 0.82 to 1.22, indicating an effect of vemurafenib on digoxin. Multiple oral doses of vemurafenib were generally well tolerated, with an adverse event profile similar to that previously seen in phase 2 and 3 studies of vemurafenib monotherapy. This study confirmed vemurafenib as an inhibitor of P-gp in vivo with a statistically significant drug-drug interaction with digoxin. Caution should be exercised when dosing vemurafenib concurrently with P-gp substrates. © 2018, The American College of Clinical Pharmacology.

Tolerance of young infants to a single, large dose of vitamin A: a randomized community trial in Nepal.

PubMed

West, K P; Khatry, S K; LeClerq, S C; Adhikari, R; See, L; Katz, J; Shrestha, S R; Pradhan, E K; Pokhrel, R P; Sommer, A

1992-01-01

A randomized, double-masked trial was carried out in rural Nepal to investigate the incidence and severity of acute side-effects among neonates ( < 1 month of age) and infants aged 1-6 months who received a large, oral dose of vitamin A (15,000 retinol equivalents (RE) (50,000 IU) and 30,000 RE (100,000 IU), respectively) or placebo (75 RE (250 IU) and 150 RE (500 IU), respectively) in oil. Infants (vitamin A group, n = 1461; controls, n = 1379) were assessed for vomiting, loose stools, fever, and irritability during the 24 hours before and after dosing. Fontanelles were palpated 24 hours after dosing. Neonates exhibited no excess risk of adverse side-effects after receiving 15,000 RE. Compared with controls the older infants who ingested 30,000 RE had a 1.6% excess rate of vomiting (95% confidence interval (CI): 0.2-3.0%) and a 0.5% excess rate (95% CI: -0.1 to 1.1%) in the occurrence of bulging fontanelles. There were no other significant differences in the older infants. The controlled, periodic distribution of a single 15,000 RE dose of vitamin A therefore confers no apparent acute risk to young infants; a 30,000 RE dose is associated with a minimum risk of transient, acute side-effects.

Neutron equivalent doses and associated lifetime cancer incidence risks for head & neck and spinal proton therapy

NASA Astrophysics Data System (ADS)

Athar, Basit S.; Paganetti, Harald

2009-08-01

In this work we have simulated the absorbed equivalent doses to various organs distant to the field edge assuming proton therapy treatments of brain or spine lesions. We have used computational whole-body (gender-specific and age-dependent) voxel phantoms and considered six treatment fields with varying treatment volumes and depths. The maximum neutron equivalent dose to organs near the field edge was found to be approximately 8 mSv Gy-1. We were able to clearly demonstrate that organ-specific neutron equivalent doses are age (stature) dependent. For example, assuming an 8-year-old patient, the dose to brain from the spinal fields ranged from 0.04 to 0.10 mSv Gy-1, whereas the dose to the brain assuming a 9-month-old patient ranged from 0.5 to 1.0 mSv Gy-1. Further, as the field aperture opening increases, the secondary neutron equivalent dose caused by the treatment head decreases, while the secondary neutron equivalent dose caused by the patient itself increases. To interpret the dosimetric data, we analyzed second cancer incidence risks for various organs as a function of patient age and field size based on two risk models. The results show that, for example, in an 8-year-old female patient treated with a spinal proton therapy field, breasts, lungs and rectum have the highest radiation-induced lifetime cancer incidence risks. These are estimated to be 0.71%, 1.05% and 0.60%, respectively. For an 11-year-old male patient treated with a spinal field, bronchi and rectum show the highest risks of 0.32% and 0.43%, respectively. Risks for male and female patients increase as their age at treatment time decreases.

Equivalent dose and effective dose from stray radiation during passively scattered proton radiotherapy for prostate cancer

NASA Astrophysics Data System (ADS)

Fontenot, Jonas; Taddei, Phillip; Zheng, Yuanshui; Mirkovic, Dragan; Jordan, Thomas; Newhauser, Wayne

2008-03-01

Proton therapy reduces the integral therapeutic dose required for local control in prostate patients compared to intensity-modulated radiotherapy. One proposed benefit of this reduction is an associated decrease in the incidence of radiogenic secondary cancers. However, patients are also exposed to stray radiation during the course of treatment. The purpose of this study was to quantify the stray radiation dose received by patients during proton therapy for prostate cancer. Using a Monte Carlo model of a proton therapy nozzle and a computerized anthropomorphic phantom, we determined that the effective dose from stray radiation per therapeutic dose (E/D) for a typical prostate patient was approximately 5.5 mSv Gy-1. Sensitivity analysis revealed that E/D varied by ±30% over the interval of treatment parameter values used for proton therapy of the prostate. Equivalent doses per therapeutic dose (HT/D) in specific organs at risk were found to decrease with distance from the isocenter, with a maximum of 12 mSv Gy-1 in the organ closest to the treatment volume (bladder) and 1.9 mSv Gy-1 in the furthest (esophagus). Neutrons created in the nozzle predominated effective dose, though neutrons created in the patient contributed substantially to the equivalent dose in organs near the proton field. Photons contributed less than 15% to equivalent doses.

Radiation brain dose to vascular surgeons during fluoroscopically guided interventions is not effectively reduced by wearing lead equivalent surgical caps.

PubMed

Kirkwood, Melissa L; Arbique, Gary M; Guild, Jeffrey B; Zeng, Katie; Xi, Yin; Rectenwald, John; Anderson, Jon A; Timaran, Carlos

2018-03-12

Radiation to the interventionalist's brain during fluoroscopically guided interventions (FGIs) may increase the incidence of cerebral neoplasms. Lead equivalent surgical caps claim to reduce radiation brain doses by 50% to 95%. We sought to determine the efficacy of the RADPAD (Worldwide Innovations & Technologies, Lenexa, Kan) No Brainer surgical cap (0.06 mm lead equivalent at 90 kVp) in reducing radiation dose to the surgeon's and trainee's head during FGIs and to a phantom to determine relative brain dose reductions. Optically stimulated, luminescent nanoDot detectors (Landauer, Glenwood, Ill) inside and outside of the cap at the left temporal position were used to measure cap attenuation during FGIs. To check relative brain doses, nanoDot detectors were placed in 15 positions within an anthropomorphic head phantom (ATOM model 701; CIRS, Norfolk, Va). The phantom was positioned to represent a primary operator performing femoral access. Fluorography was performed on a plastic scatter phantom at 80 kVp for an exposure of 5 Gy reference air kerma with or without the hat. For each brain location, the percentage dose reduction with the hat was calculated. Means and standard errors were calculated using a pooled linear mixed model with repeated measurements. Anatomically similar locations were combined into five groups: upper brain, upper skull, midbrain, eyes, and left temporal position. This was a prospective, single-center study that included 29 endovascular aortic aneurysm procedures. The average procedure reference air kerma was 2.6 Gy. The hat attenuation at the temporal position for the attending physician and fellow was 60% ± 20% and 33% ± 36%, respectively. The equivalent phantom measurements demonstrated an attenuation of 71% ± 2.0% (P < .0001). In the interior phantom locations, attenuation was statistically significant for the skull (6% ± 1.4%) and upper brain (7.2% ± 1.0%; P < .0001) but not for the middle brain (1.4% ± 1.0%; P = .15) or the eyes (-1.5% ± 1.4%; P = .28). The No Brainer surgical cap attenuates direct X rays at the superficial temporal location; however, the majority of radiation to an interventionalist's brain originates from scatter radiation from angles not shadowed by the cap as demonstrated by the trivial percentage brain dose reductions measured in the phantom. Radiation protective caps have minimal clinical relevance. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

A Double-Blind, Double-Dummy, Flexible-Design Randomized Multicenter Trial: Early Safety of Single- Versus Divided-Dose Rabbit Anti-Thymocyte Globulin Induction in Renal Transplantation.

PubMed

Stevens, R B; Wrenshall, L E; Miles, C D; Farney, A C; Jie, T; Sandoz, J P; Rigley, T H; Osama Gaber, A

2016-06-01

A previous nonblinded, randomized, single-center renal transplantation trial of single-dose rabbit anti-thymocyte globulin induction (SD-rATG) showed improved efficacy compared with conventional divided-dose (DD-rATG) administration. The present multicenter, double-blind/double-dummy STAT trial (Single dose vs. Traditional Administration of Thymoglobulin) evaluated SD-rATG versus DD-rATG induction for noninferiority in early (7-day) safety and tolerability. Ninety-five patients (randomized 1:1) received 6 mg/kg SD-rATG or 1.5 mg/kg/dose DD-rATG, with tacrolimus-mycophenolate maintenance immunosuppression. The primary end point was a composite of fever, hypoxia, hypotension, cardiac complications, and delayed graft function. Secondary end points included 12-month patient survival, graft survival, and rejection. Target enrollment was 165 patients with an interim analysis scheduled after 80 patients. Interim analysis showed primary end point noninferiority of SD-rATG induction (p = 0.6), and a conditional probability of <1.73% of continued enrollment producing a significant difference (futility analysis), leading to early trial termination. Final analysis (95 patients) showed no differences in occurrence of primary end point events (p = 0.58) or patients with no, one, or more than one event (p = 0.81), or rejection, graft, or patient survival (p = 0.78, 0.47, and 0.35, respectively). In this rigorously blinded trial in adult renal transplantation, we have shown SD-rATG induction to be noninferior to DD-rATG induction in early tolerability and equivalent in 12-month safety. (Clinical Trials.gov #NCT00906204.). © Copyright 2016 The Authors. American Journal of Transplantation published by Wiley Periodicals, Inc. on behalf of the American Society of Transplantation and the American Society of Transplant Surgeons.

Cosmic ray LET spectra and doses on board Cosmos-2044 biosatellite

NASA Technical Reports Server (NTRS)

Dudkin, V. E.; Kovalev, E. E.; Potapov, Y. V.; Benton, E. V.; Frank, A. L.; Benton, E. R.; Watts, J. W. Jr; Parnell, T. A.; Schopper, E.; Baican, B.;

β-blocker dosage and outcomes after acute coronary syndrome.

PubMed

Allen, Jason E; Knight, Stacey; McCubrey, Raymond O; Bair, Tami; Muhlestein, Joseph Brent; Goldberger, Jeffrey J; Anderson, Jeffrey L

2017-02-01

Although β-blockers increase survival in acute coronary syndrome (ACS) patients, the doses used in trials were higher than doses used in practice, and recent data do not support an advantage of higher doses. We hypothesized that rates of major adverse cardiac events (MACE), all-cause death, myocardial infarction, and stroke are equivalent for patients on low-dose and high-dose β-blocker. Patients admitted to Intermountain Healthcare with ACS and diagnosed with ≥70% coronary stenosis between 1994 and 2013 were studied (N = 7,834). We classified low dose as ≤25% and high dose as ≥50% of an equivalent daily dose of 200 mg of metoprolol. Multivariate analyses were used to test association between low-dose versus high-dose β-blocker dosage and MACE at 0-6 months and 6-24 months. A total of 5,287 ACS subjects were discharged on β-blockers (87% low dose, 12% high dose, and 1% intermediate dose). The 6-month MACE outcomes rates for the β-blocker dosage (low versus high) were not equivalent (P = .18) (hazard ratio [HR] = 0.76; 95% CI, 0.52-1.10). However, subjects on low-dose β-blocker therapy did have a significantly decreased risk of myocardial infarction for 0-6 months (HR = 0.53; 95% CI, 0.33-0.86). The rates of MACE events during the 6-24 months after presentation with ACS were equivalent for the 2 doses (P = .009; HR = 1.03 [95% CI, 0.70-1.50]). In ACS patients, rates of MACE for high-dose and low-dose β-blocker doses are similar. These findings question the importance of achieving a high dose of β-blocker in ACS patients and highlight the need for further investigation of this clinical question. Copyright © 2016 Elsevier Inc. All rights reserved.

The development and validation of a Monte Carlo model for calculating the out-of-field dose from radiotherapy treatments

NASA Astrophysics Data System (ADS)

Kry, Stephen

Introduction. External beam photon radiotherapy is a common treatment for many malignancies, but results in the exposure of the patient to radiation away from the treatment site. This out-of-field radiation irradiates healthy tissue and may lead to the induction of secondary malignancies. Out-of-field radiation is composed of photons and, at high treatment energies, neutrons. Measurement of this out-of-field dose is time consuming, often difficult, and is specific to the conditions of the measurements. Monte Carlo simulations may be a viable approach to determining the out-of-field dose quickly, accurately, and for arbitrary irradiation conditions. Methods. An accelerator head, gantry, and treatment vault were modeled with MCNPX and 6 MV and 18 MV beams were simulated. Photon doses were calculated in-field and compared to measurements made with an ion chamber in a water tank. Photon doses were also calculated out-of-field from static fields and compared to measurements made with thermoluminescent dosimeters in acrylic. Neutron fluences were calculated and compared to measurements made with gold foils. Finally, photon and neutron dose equivalents were calculated in an anthropomorphic phantom following intensity-modulated radiation therapy and compared to previously published dose equivalents. Results. The Monte Carlo model was able to accurately calculate the in-field dose. From static treatment fields, the model was also able to calculate the out-of-field photon dose within 16% at 6 MV and 17% at 18 MV and the neutron fluence within 19% on average. From the simulated IMRT treatments, the calculated out-of-field photon dose was within 14% of measurement at 6 MV and 13% at 18 MV on average. The calculated neutron dose equivalent was much lower than the measured value but is likely accurate because the measured neutron dose equivalent was based on an overestimated neutron energy. Based on the calculated out-of-field doses generated by the Monte Carlo model, it was possible to estimate the risk of fatal secondary malignancy, which was consistent with previous estimates except for the neutron discrepancy. Conclusions. The Monte Carlo model developed here is well suited to studying the out-of-field dose equivalent from photons and neutrons under a variety of irradiation configurations, including complex treatments on complex phantoms. Based on the calculated dose equivalents, it is possible to estimate the risk of secondary malignancy associated with out-of-field doses. The Monte Carlo model should be used to study, quantify, and minimize the out-of-field dose equivalent and associated risks received by patients undergoing radiation therapy.

Placental transfer and pharmacokinetics of a single oral dose of [14C]p-nitrophenol in rats.

PubMed

Abu-Qare, A W; Brownie, C F; Abou-Donia, M B

2000-09-01

The pharmacokinetics and placental transfer of a single oral dose of 100 mg/kg (10 microCi/kg, 16% of acute oral LD50) of uniformly phenyl-labeled [14C]p-nitrophenol were investigated in pregnant Sprague-Dawley rats at 14-18 days of gestation. Three animals were killed on gestation day 18, at 0.5, 1, 2, 4, 12, 24, and 48 h after dosing. Radioactivity was rapidly absorbed and distributed throughout the maternal and fetal tissues. The gastrointestinal tract contents retained 20% and 2% of the dose at 0.5 h and 4 h after dosing. The peak maternal plasma concentration of radioactivity (microg p-nitrophenol equivalent/ml) was 7.17 compared with 0.37 for fetal plasma at 0.5 h. Maximum concentration of radioactivity (microg p-nitrophenol equivalent/g fresh tissue) was detected in most tissues 0.5 h after dosing and was in descending order: kidney 23.27, liver 12.37, placenta 3.56, fetus 2.17, and brain 1.99. Radioactivity was eliminated from plasma and all tissues beiexponentially. The half-lives of elimination of 14C were 34.65 h and 69.30 h for maternal and fetal plasma, respectively. p-Nitrophenol, detected by HPLC, was the major compound identified in plasma and tissues. While p-nitrophenol disappeared biphasically from maternal plasma and kidney, it was eliminated monophasically from brain, placenta, and liver. p-Nitrocatechol and p-aminophenol were detected in the liver with peak concentrations at 0.5 h of 1.13 and 1.00 microg/g fresh tissue, respectively. While the change in the concentration of p-nitrocatechol with time was monophasic, that of p-aminophenol showed a biphasic pattern with elimination half-lives of 1.93 h and 4.95 h, respectively. Radioactivity was rapidly excreted in the urine mostly as polar metabolites, while only 3% of the dose was recovered in the feces. Radioactive materials excreted in the urine comprised: glucuronides 4%, sulfates 8%, hot-acid hydrolysates 11%, nonconjugated compounds 16%, and water-soluble metabolites 61%. This study demonstrated that although orally administered p-nitrophenol is a rapidly absorbed and excreted compound, it is transported to the maternal brain and the fetus and may pose a health risk following exposure to toxic doses during pregnancy.

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2010 CFR

2010-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2010-01-01 2010-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2014 CFR

2014-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2014-01-01 2014-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2012 CFR

2012-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2012-01-01 2012-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2013 CFR

2013-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2013-01-01 2013-01-01 false Occupational dose limits for general employees. 835.202...

10 CFR 835.202 - Occupational dose limits for general employees.

Code of Federal Regulations, 2011 CFR

2011-01-01

... tissue other than the skin or the lens of the eye of 50 rems (0.5 Sv); (3) An equivalent dose to the lens of the eye of 15 rems (0.15 Sv); and (4) The sum of the equivalent dose to the skin or to any... 10 Energy 4 2011-01-01 2011-01-01 false Occupational dose limits for general employees. 835.202...

SU-E-T-409: Evaluation of Tissue Composition Effect On Dose Distribution in Radiotherapy with 6 MV Photon Beam of a Medical Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghorbani, M; Tabatabaei, Z; Noghreiyan, A Vejdani

Purpose: The aim of this study is to evaluate soft tissue composition effect on dose distribution for various soft tissues and various depths in radiotherapy with 6 MV photon beam of a medical linac. Methods: A phantom and Siemens Primus linear accelerator were simulated using MCNPX Monte Carlo code. In a homogeneous cubic phantom, six types of soft tissue and three types of tissue-equivalent materials were defined separately. The soft tissues were muscle (skeletal), adipose tissue, blood (whole), breast tissue, soft tissue (9-component) and soft tissue (4-component). The tissue-equivalent materials included: water, A-150 tissue-equivalent plastic and perspex. Photon dose relativemore » to dose in 9-component soft tissue at various depths on the beam’s central axis was determined for the 6 MV photon beam. The relative dose was also calculated and compared for various MCNPX tallies including,F8, F6 and,F4. Results: The results of the relative photon dose in various materials relative to dose in 9-component soft tissue and using different tallies are reported in the form of tabulated data. Minor differences between dose distributions in various soft tissues and tissue-equivalent materials were observed. The results from F6 and F4 were practically the same but different with,F8 tally. Conclusion: Based on the calculations performed, the differences in dose distributions in various soft tissues and tissue-equivalent materials are minor but they could be corrected in radiotherapy calculations to upgrade the accuracy of the dosimetric calculations.« less

Ambient Dose Equivalent measured at the Instituto Nacional de Cancerología Department of Nuclear Medicine

NASA Astrophysics Data System (ADS)

Ávila, O.; Torres-Ulloa, C. L.; Medina, L. A.; Trujillo-Zamudio, F. E.; de Buen, I. Gamboa; Buenfil, A. E.; Brandan, M. E.

2010-12-01

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerología, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with 137Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrología, to known 137Cs gamma radiation air kerma. Radionuclides considered for this study are 131I, 18F, 67Ga, 99mTc, 111In, 201Tl and 137Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placed during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with 131I and 137Cs. High dose values were found at the waste storage room, outside corridor of 137Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the 137Cs brachytherapy corridor is equal to (18.51±0.02)×10-3 mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05±0.03)×10-3 mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).

The effect of statistical noise on IMRT plan quality and convergence for MC-based and MC-correction-based optimized treatment plans.

PubMed

Siebers, Jeffrey V

2008-04-04

Monte Carlo (MC) is rarely used for IMRT plan optimization outside of research centres due to the extensive computational resources or long computation times required to complete the process. Time can be reduced by degrading the statistical precision of the MC dose calculation used within the optimization loop. However, this eventually introduces optimization convergence errors (OCEs). This study determines the statistical noise levels tolerated during MC-IMRT optimization under the condition that the optimized plan has OCEs <100 cGy (1.5% of the prescription dose) for MC-optimized IMRT treatment plans.Seven-field prostate IMRT treatment plans for 10 prostate patients are used in this study. Pre-optimization is performed for deliverable beams with a pencil-beam (PB) dose algorithm. Further deliverable-based optimization proceeds using: (1) MC-based optimization, where dose is recomputed with MC after each intensity update or (2) a once-corrected (OC) MC-hybrid optimization, where a MC dose computation defines beam-by-beam dose correction matrices that are used during a PB-based optimization. Optimizations are performed with nominal per beam MC statistical precisions of 2, 5, 8, 10, 15, and 20%. Following optimizer convergence, beams are re-computed with MC using 2% per beam nominal statistical precision and the 2 PTV and 10 OAR dose indices used in the optimization objective function are tallied. For both the MC-optimization and OC-optimization methods, statistical equivalence tests found that OCEs are less than 1.5% of the prescription dose for plans optimized with nominal statistical uncertainties of up to 10% per beam. The achieved statistical uncertainty in the patient for the 10% per beam simulations from the combination of the 7 beams is ~3% with respect to maximum dose for voxels with D>0.5D(max). The MC dose computation time for the OC-optimization is only 6.2 minutes on a single 3 Ghz processor with results clinically equivalent to high precision MC computations.

A comparison of quantum limited dose and noise equivalent dose

NASA Astrophysics Data System (ADS)

Job, Isaias D.; Boyce, Sarah J.; Petrillo, Michael J.; Zhou, Kungang

2016-03-01

Quantum-limited-dose (QLD) and noise-equivalent-dose (NED) are performance metrics often used interchangeably. Although the metrics are related, they are not equivalent unless the treatment of electronic noise is carefully considered. These metrics are increasingly important to properly characterize the low-dose performance of flat panel detectors (FPDs). A system can be said to be quantum-limited when the Signal-to-noise-ratio (SNR) is proportional to the square-root of x-ray exposure. Recent experiments utilizing three methods to determine the quantum-limited dose range yielded inconsistent results. To investigate the deviation in results, generalized analytical equations are developed to model the image processing and analysis of each method. We test the generalized expression for both radiographic and fluoroscopic detectors. The resulting analysis shows that total noise content of the images processed by each method are inherently different based on their readout scheme. Finally, it will be shown that the NED is equivalent to the instrumentation-noise-equivalent-exposure (INEE) and furthermore that the NED is derived from the quantum-noise-only method of determining QLD. Future investigations will measure quantum-limited performance of radiographic panels with a modified readout scheme to allow for noise improvements similar to measurements performed with fluoroscopic detectors.

Calculated organ doses using Monte Carlo simulations in a reference male phantom undergoing HDR brachytherapy applied to localized prostate carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candela-Juan, Cristian; Perez-Calatayud, Jose; Ballester, Facundo

Purpose: The aim of this study was to obtain equivalent doses in radiosensitive organs (aside from the bladder and rectum) when applying high-dose-rate (HDR) brachytherapy to a localized prostate carcinoma using {sup 60}Co or {sup 192}Ir sources. These data are compared with results in a water phantom and with expected values in an infinite water medium. A comparison with reported values from proton therapy and intensity-modulated radiation therapy (IMRT) is also provided. Methods: Monte Carlo simulations in Geant4 were performed using a voxelized phantom described in International Commission on Radiological Protection (ICRP) Publication 110, which reproduces masses and shapes frommore » an adult reference man defined in ICRP Publication 89. Point sources of {sup 60}Co or {sup 192}Ir with photon energy spectra corresponding to those exiting their capsules were placed in the center of the prostate, and equivalent doses per clinical absorbed dose in this target organ were obtained in several radiosensitive organs. Values were corrected to account for clinical circumstances with the source located at various positions with differing dwell times throughout the prostate. This was repeated for a homogeneous water phantom. Results: For the nearest organs considered (bladder, rectum, testes, small intestine, and colon), equivalent doses given by {sup 60}Co source were smaller (8%-19%) than from {sup 192}Ir. However, as the distance increases, the more penetrating gamma rays produced by {sup 60}Co deliver higher organ equivalent doses. The overall result is that effective dose per clinical absorbed dose from a {sup 60}Co source (11.1 mSv/Gy) is lower than from a {sup 192}Ir source (13.2 mSv/Gy). On the other hand, equivalent doses were the same in the tissue and the homogeneous water phantom for those soft tissues closer to the prostate than about 30 cm. As the distance increased, the differences of photoelectric effect in water and soft tissue, and appearance of other materials such as air, bone, or lungs, produced variations between both phantoms which were at most 35% in the considered organ equivalent doses. Finally, effective doses per clinical absorbed dose from IMRT and proton therapy were comparable to those from both brachytherapy sources, with brachytherapy being advantageous over external beam radiation therapy for the furthest organs. Conclusions: A database of organ equivalent doses when applying HDR brachytherapy to the prostate with either {sup 60}Co or {sup 192}Ir is provided. According to physical considerations, {sup 192}Ir is dosimetrically advantageous over {sup 60}Co sources at large distances, but not in the closest organs. Damage to distant healthy organs per clinical absorbed dose is lower with brachytherapy than with IMRT or protons, although the overall effective dose per Gy given to the prostate seems very similar. Given that there are several possible fractionation schemes, which result in different total amounts of therapeutic absorbed dose, advantage of a radiation treatment (according to equivalent dose to healthy organs) is treatment and facility dependent.« less

Evaluation of Exposure From a Low Energy X-Ray Device Using Thermoluminescent Dosimeters

NASA Technical Reports Server (NTRS)

Edwards, David L.; Harris, William S., Jr.

1997-01-01

The exposure from an electron beam welding device was evaluated using thermoluminescent dosimeters (TLDs). The device generated low energy X-rays which the current dose equivalent conversion algorithm was not designed to evaluate making it necessary to obtain additional information relating to TLD operation at the photon energies encountered with the device. This was accomplished by performing irradiations at the National Institute of Standards and Technology (NIST) using low energy X-ray techniques. The resulting data was used to determine TLD badge response for low energy X-rays and to establish the relationship between TLD element response and the dose equivalent at specific depths in tissue for these photon energies. The new energy/dose equivalent calibration data was used to calculate the shallow and eye dose equivalent of badges exposed to the device.

Measurement of absorbed dose with a bone-equivalent extrapolation chamber.

PubMed

DeBlois, François; Abdel-Rahman, Wamied; Seuntjens, Jan P; Podgorsak, Ervin B

2002-03-01

A hybrid phantom-embedded extrapolation chamber (PEEC) made of Solid Water and bone-equivalent material was used for determining absorbed dose in a bone-equivalent phantom irradiated with clinical radiation beams (cobalt-60 gamma rays; 6 and 18 MV x rays; and 9 and 15 MeV electrons). The dose was determined with the Spencer-Attix cavity theory, using ionization gradient measurements and an indirect determination of the chamber air-mass through measurements of chamber capacitance. The collected charge was corrected for ionic recombination and diffusion in the chamber air volume following the standard two-voltage technique. Due to the hybrid chamber design, correction factors accounting for scatter deficit and electrode composition were determined and applied in the dose equation to obtain absorbed dose in bone for the equivalent homogeneous bone phantom. Correction factors for graphite electrodes were calculated with Monte Carlo techniques and the calculated results were verified through relative air cavity dose measurements for three different polarizing electrode materials: graphite, steel, and brass in conjunction with a graphite collecting electrode. Scatter deficit, due mainly to loss of lateral scatter in the hybrid chamber, reduces the dose to the air cavity in the hybrid PEEC in comparison with full bone PEEC by 0.7% to approximately 2% depending on beam quality and energy. In megavoltage photon and electron beams, graphite electrodes do not affect the dose measurement in the Solid Water PEEC but decrease the cavity dose by up to 5% in the bone-equivalent PEEC even for very thin graphite electrodes (<0.0025 cm). In conjunction with appropriate correction factors determined with Monte Carlo techniques, the uncalibrated hybrid PEEC can be used for measuring absorbed dose in bone material to within 2% for high-energy photon and electron beams.

Dose estimation for astronauts using dose conversion coefficients calculated with the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Sihver, Lembit; Niita, Koji

2011-03-01

Absorbed-dose and dose-equivalent rates for astronauts were estimated by multiplying fluence-to-dose conversion coefficients in the units of Gy.cm(2) and Sv.cm(2), respectively, and cosmic-ray fluxes around spacecrafts in the unit of cm(-2) s(-1). The dose conversion coefficients employed in the calculation were evaluated using the general-purpose particle and heavy ion transport code system PHITS coupled to the male and female adult reference computational phantoms, which were released as a common ICRP/ICRU publication. The cosmic-ray fluxes inside and near to spacecrafts were also calculated by PHITS, using simplified geometries. The accuracy of the obtained absorbed-dose and dose-equivalent rates was verified by various experimental data measured both inside and outside spacecrafts. The calculations quantitatively show that the effective doses for astronauts are significantly greater than their corresponding effective dose equivalents, because of the numerical incompatibility between the radiation quality factors and the radiation weighting factors. These results demonstrate the usefulness of dose conversion coefficients in space dosimetry. © Springer-Verlag 2010

Heuristic knowledge-based planning for single-isocenter stereotactic radiosurgery to multiple brain metastases.

PubMed

Ziemer, Benjamin P; Sanghvi, Parag; Hattangadi-Gluth, Jona; Moore, Kevin L

2017-10-01

Single-isocenter, volumetric-modulated arc therapy (VMAT) stereotactic radiosurgery (SRS) for multiple brain metastases (multimets) can deliver highly conformal dose distributions and reduce overall patient treatment time compared to other techniques. However, treatment planning for multimet cases is highly complex due to variability in numbers and sizes of brain metastases, as well as their relative proximity to organs-at-risk (OARs). The purpose of this study was to automate the VMAT planning of multimet cases through a knowledge-based planning (KBP) approach that adapts single-target SRS dose predictions to multiple target predictions. Using a previously published artificial neural network (ANN) KBP system trained on single-target, linac-based SRS plans, 3D dose distribution predictions for multimet patients were obtained by treating each brain lesion as a solitary target and subsequently combining individual dose predictions into a single distribution. Spatial dose distributions di(r→) for each of the i = 1…N lesions were merged using the combination function d(r→)=∑iNdin(r→)1/n. The optimal value of n was determined by minimizing root-mean squared (RMS) difference between clinical multimet plans and predicted dose per unit length along the line profile joining each lesion in the clinical cohort. The gradient measure GM=[3/4π]1/3V50%1/3-V100%1/3 is the primary quality metric for SRS plan evaluation at our institution and served as the main comparative metric between clinical plans and the KBP results. A total of 41 previously treated multimet plans, with target numbers ranging from N = 2-10, were used to validate the ANN predictions and subsequent KBP auto-planning routine. Fully deliverable KBP plans were developed by converting predicted dose distribution into patient-specific optimization objectives for the clinical treatment planning system (TPS). Plan parity was maintained through identical arc configuration and target normalization. Overall plan quality improvements were quantified by calculating the difference between SRS quality metrics (QMs): ΔQM = QM clinical  - QM KBP . In addition to GM, investigated QMs were: volume of brain receiving ≥ 10 Gy (V 10 Gy ), volume of brain receiving ≥ 5 Gy (ΔV 5 Gy ), heterogeneity index (HI), dose to 0.1 cc of the brainstem (D 0.1 cc ), dose to 1% of the optic chiasm (D 1% ), and interlesion dose (D IL ). In addition to this quantitative analysis, overall plan quality was assessed via blinded plan comparison of the manual and KBP treatment plans by SRS-specializing physicians. A dose combination factor of n = 8 yielded an integrated dose profile RMS difference of 2.9% across the 41-patient cohort. Multimet dose predictions exhibited ΔGM = 0.07 ± 0.10 cm against the clinical sample, implying either further normal tissue sparing was possible or that dose predictions were slightly overestimating achievable dose gradients. The latter is the more likely explanation, as this bias vanished when dose predictions were converted to deliverable KBP plans ΔGM = 0.00 ± 0.08 cm. Remaining QMs were nearly identical or showed modest improvements in the KBP sample. Equivalent QMs included: ΔV 10 Gy  = 0.37 ± 3.78 cc, ΔHI = 0.02 ± 0.08 and ΔD IL  = -2.22 ± 171.4 cGy. The KBP plans showed a greater degree of normal tissue sparing as indicated by brain ΔV 5 Gy  = 4.11± 24.05 cc, brainstem ΔD 0.1 cc  = 42.8 ± 121.4 cGy, and chiasm ΔD 1%  = 50.8 ± 83.0 cGy. In blinded review by SRS-specializing physicians, KBP-generated plans were deemed equivalent or superior in 32/41(78.1%) of the cases. Heuristic KBP-driven automated planning in linac-based, single-isocenter treatments for multiple brain metastases maintained or exceeded overall plan quality. © 2017 American Association of Physicists in Medicine.

Dose equivalent rate constants and barrier transmission data for nuclear medicine facility dose calculations and shielding design.

PubMed

Kusano, Maggie; Caldwell, Curtis B

2014-07-01

A primary goal of nuclear medicine facility design is to keep public and worker radiation doses As Low As Reasonably Achievable (ALARA). To estimate dose and shielding requirements, one needs to know both the dose equivalent rate constants for soft tissue and barrier transmission factors (TFs) for all radionuclides of interest. Dose equivalent rate constants are most commonly calculated using published air kerma or exposure rate constants, while transmission factors are most commonly calculated using published tenth-value layers (TVLs). Values can be calculated more accurately using the radionuclide's photon emission spectrum and the physical properties of lead, concrete, and/or tissue at these energies. These calculations may be non-trivial due to the polyenergetic nature of the radionuclides used in nuclear medicine. In this paper, the effects of dose equivalent rate constant and transmission factor on nuclear medicine dose and shielding calculations are investigated, and new values based on up-to-date nuclear data and thresholds specific to nuclear medicine are proposed. To facilitate practical use, transmission curves were fitted to the three-parameter Archer equation. Finally, the results of this work were applied to the design of a sample nuclear medicine facility and compared to doses calculated using common methods to investigate the effects of these values on dose estimates and shielding decisions. Dose equivalent rate constants generally agreed well with those derived from the literature with the exception of those from NCRP 124. Depending on the situation, Archer fit TFs could be significantly more accurate than TVL-based TFs. These results were reflected in the sample shielding problem, with unshielded dose estimates agreeing well, with the exception of those based on NCRP 124, and Archer fit TFs providing a more accurate alternative to TVL TFs and a simpler alternative to full spectral-based calculations. The data provided by this paper should assist in improving the accuracy and tractability of dose and shielding calculations for nuclear medicine facility design.

Space dosimetry with the application of a 3D silicon detector telescope: response function and inverse algorithm.

PubMed

Pázmándi, Tamás; Deme, Sándor; Láng, Edit

2006-01-01

One of the many risks of long-duration space flights is the excessive exposure to cosmic radiation, which has great importance particularly during solar flares and higher sun activity. Monitoring of the cosmic radiation on board space vehicles is carried out on the basis of wide international co-operation. Since space radiation consists mainly of charged heavy particles (protons, alpha and heavier particles), the equivalent dose differs significantly from the absorbed dose. A radiation weighting factor (w(R)) is used to convert absorbed dose (Gy) to equivalent dose (Sv). w(R) is a function of the linear energy transfer of the radiation. Recently used equipment is suitable for measuring certain radiation field parameters changing in space and over time, so a combination of different measurements and calculations is required to characterise the radiation field in terms of dose equivalent. The objectives of this project are to develop and manufacture a three-axis silicon detector telescope, called Tritel, and to develop software for data evaluation of the measured energy deposition spectra. The device will be able to determine absorbed dose and dose equivalent of the space radiation.

Biological effects and equivalent doses in radiotherapy: A software solution

PubMed Central

Voyant, Cyril; Julian, Daniel; Roustit, Rudy; Biffi, Katia; Lantieri, Céline

2013-01-01

Background The limits of TDF (time, dose, and fractionation) and linear quadratic models have been known for a long time. Medical physicists and physicians are required to provide fast and reliable interpretations regarding delivered doses or any future prescriptions relating to treatment changes. Aim We, therefore, propose a calculation interface under the GNU license to be used for equivalent doses, biological doses, and normal tumor complication probability (Lyman model). Materials and methods The methodology used draws from several sources: the linear-quadratic-linear model of Astrahan, the repopulation effects of Dale, and the prediction of multi-fractionated treatments of Thames. Results and conclusions The results are obtained from an algorithm that minimizes an ad-hoc cost function, and then compared to an equivalent dose computed using standard calculators in seven French radiotherapy centers. PMID:24936319

Quantifying the Combined Effect of Radiation Therapy and Hyperthermia in Terms of Equivalent Dose Distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kok, H. Petra, E-mail: H.P.Kok@amc.uva.nl; Crezee, Johannes; Franken, Nicolaas A.P.

2014-03-01

Purpose: To develop a method to quantify the therapeutic effect of radiosensitization by hyperthermia; to this end, a numerical method was proposed to convert radiation therapy dose distributions with hyperthermia to equivalent dose distributions without hyperthermia. Methods and Materials: Clinical intensity modulated radiation therapy plans were created for 15 prostate cancer cases. To simulate a clinically relevant heterogeneous temperature distribution, hyperthermia treatment planning was performed for heating with the AMC-8 system. The temperature-dependent parameters α (Gy{sup −1}) and β (Gy{sup −2}) of the linear–quadratic model for prostate cancer were estimated from the literature. No thermal enhancement was assumed for normalmore » tissue. The intensity modulated radiation therapy plans and temperature distributions were exported to our in-house-developed radiation therapy treatment planning system, APlan, and equivalent dose distributions without hyperthermia were calculated voxel by voxel using the linear–quadratic model. Results: The planned average tumor temperatures T90, T50, and T10 in the planning target volume were 40.5°C, 41.6°C, and 42.4°C, respectively. The planned minimum, mean, and maximum radiation therapy doses were 62.9 Gy, 76.0 Gy, and 81.0 Gy, respectively. Adding hyperthermia yielded an equivalent dose distribution with an extended 95% isodose level. The equivalent minimum, mean, and maximum doses reflecting the radiosensitization by hyperthermia were 70.3 Gy, 86.3 Gy, and 93.6 Gy, respectively, for a linear increase of α with temperature. This can be considered similar to a dose escalation with a substantial increase in tumor control probability for high-risk prostate carcinoma. Conclusion: A model to quantify the effect of combined radiation therapy and hyperthermia in terms of equivalent dose distributions was presented. This model is particularly instructive to estimate the potential effects of interaction from different treatment modalities.« less

Solar particle event organ doses and dose equivalents for interplanetary crews: variations due to body size

NASA Technical Reports Server (NTRS)

Zapp, E. N.; Townsend, L. W.; Cucinotta, F. A.

2002-01-01

Proper assessments of spacecraft shielding requirements and concomitant estimates of risk to critical body organs of spacecraft crews from energetic space radiation require accurate, quantitative methods of characterizing the compositional changes in these radiation fields as they pass through the spacecraft and overlying tissue. When estimating astronaut radiation organ doses and dose equivalents it is customary to use the Computerized Anatomical Man (CAM) model of human geometry to account for body self-shielding. Usually, the distribution for the 50th percentile man (175 cm height; 70 kg mass) is used. Most male members of the U.S. astronaut corps are taller and nearly all have heights that deviate from the 175 cm mean. In this work, estimates of critical organ doses and dose equivalents for interplanetary crews exposed to an event similar to the October 1989 solar particle event are presented for male body sizes that vary from the 5th to the 95th percentiles. Overall the results suggest that calculations of organ dose and dose equivalent may vary by as much as approximately 15% as body size is varied from the 5th to the 95th percentile in the population used to derive the CAM model data. c2002 Published by Elsevier Science Ltd on behalf of COSPAR.

Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device

PubMed Central

Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C.; Marino, Stephen A.; Geard, Charles R.; Brenner, David J.; Garty, Guy

2015-01-01

We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

PubMed

Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

2015-10-01

We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields.

High energy neutron dosimeter

DOEpatents

Sun, Rai Ko S.F.

1994-01-01

A device for measuring dose equivalents in neutron radiation fields. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning.

Assessment of radiation doses from residential smoke detectors that contain americium-241

NASA Astrophysics Data System (ADS)

Odonnell, F. R.; Etnier, E. L.; Holton, G. A.; Travis, C. C.

1981-10-01

External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv to 20 nSv for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 micro-Sv (0.0006 to 8 mrem) to total body and from 0.06 to 800 micro-Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft squared.

Neutron scattered dose equivalent to a fetus from proton radiotherapy of the mother.

PubMed

Mesoloras, Geraldine; Sandison, George A; Stewart, Robert D; Farr, Jonathan B; Hsi, Wen C

2006-07-01

Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts (mSv) per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the lower confidence limit for the threshold of 300 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However, based on the linear no threshold hypothesis, and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10,000 children.

Impact of organic polyelectrolytes on coagulation of source-separated black water.

PubMed

Kozminykh, Pavlo; Heistad, Arve; Ratnaweera, Harsha C; Todt, Daniel

2016-01-01

Household wastewater is originated from common people's activities and has a potential harmful impact on the environment if discharged directly without proper treatment. Toilet wastewater or black water (BW) contains urine, faeces, toilet paper and flushing water and it contains the majority of pollutants obtained from a single household. In this study, the focus was on BW treatment using chemical methods. The main goal of current research was to define the possibility and applicability of conventional coagulants and flocculants in direct chemical treatment of vacuum-collected BW to remove particles, organic matter and phosphorous. After the definition of dosing ranges, based on the equivalent doses in conventional municipal and industrial wastewater treatment data, aluminium and iron coagulants, organic polyelectrolytes (polymers with anionic, neutral and cationic charge with different molecular weights) and their various combinations were tested using the well-known jar-test laboratory method to study aggregation and solid-liquid separation processes in raw BW. The most important process parameter during the coagulation was pH level, dependent on the type and doses of metal salts. Some side processes were found to occur while using iron-based coagulants. Dosing of either single coagulants or single polymers did not give satisfactory results, while a combination of aluminium salts and cationic polymers showed high removal rates in total suspended solids, total chemical oxygen demand and ortho-phosphates, reaching 97.8%, 92% and 98.6%, respectively, with the optimal doses of chemicals. Cationic polymers with the lowest molecular weight and highest charge density were the most efficient in combination with aluminium coagulants.

Sci-Thur PM - Colourful Interactions: Highlights 08: ARC TBI using Single-Step Optimized VMAT Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hudson, Alana; Gordon, Deborah; Moore, Roseanne

Purpose: This work outlines a new TBI delivery technique to replace a lateral POP full bolus technique. The new technique is done with VMAT arc delivery, without bolus, treating the patient prone and supine. The benefits of the arc technique include: increased patient experience and safety, better dose conformity, better organ at risk sparing, decreased therapist time and reduction of therapist injuries. Methods: In this work we build on a technique developed by Jahnke et al. We use standard arc fields with gantry speeds corrected for varying distance to the patient followed by a single step VMAT optimization on amore » patient CT to increase dose inhomogeneity and to reduce dose to the lungs (vs. blocks). To compare the arc TBI technique to our full bolus technique, we produced plans on patient CTs for both techniques and evaluated several dosimetric parameters using an ANOVA test. Results and Conclusions: The arc technique is able reduce both the hot areas to the body (D2% reduced from 122.2% to 111.8% p<0.01) and the lungs (mean lung dose reduced from 107.5% to 99.1%, p<0.01), both statistically significant, while maintaining coverage (D98% = 97.8% vs. 94.6%, p=0.313, not statistically significant). We developed a more patient and therapist-friendly TBI treatment technique that utilizes single-step optimized VMAT plans. It was found that this technique was dosimetrically equivalent to our previous lateral technique in terms of coverage and statistically superior in terms of reduced lung dose.« less

Cosmic ray LET spectra and doses on board Cosmos-2044 biosatellite

NASA Technical Reports Server (NTRS)

Watts, J. W., Jr.; Parnell, T. A.; Dudkin, V. E.; Kovalev, E. E.; Potapov, Yu. V.; Benton, E. V.; Frank, A. L.; Benton, E. R.; Beaujean, R.; Heilmann, C.

1995-01-01

Results of the experiments on board Cosmos-2044 (Biosatellite 9) are presented. Various nuclear track detectors (NTD) (dielectric, AgCl-based, nuclear emulsions) were used to obtain the Linear Energy Transfer (LET) spectra inside and outside the satellite. The spectra from the different NTDs have proved to be in general agreement. The results of LET spectra calculations using two different models are also presented. The resultant LET distributions are used to calculate the absorbed and equivalent doses and the orbit-averaged quality factors (QF) of the cosmic rays (CR). Absorbed dose rates inside (approximately 20 g cm (exp -2) shielding) and outside (1 g cm(exp -2) the spacecraft, omitting electrons, were found to be 4.8 and 8.6 mrad d (exp -1), respectively, while the corresponding equivalent doses were 8.8 and 19.7 mrem d(exp -1). The effects of the flight parameters on the total fluence of, and on the dose from the CR particles are analyzed. Integral dose distributions of the detected particles are also determined. The LET values which separate absorbed and equivalent doses into 50% intervals are estimated. The CR-39 dielectric NTD is shown to detect 20-30% of the absorbed dose and 60-70% of the equivalent dose in the Cosmos-2044 orbit. The influence of solar activity phase on the magnitude of CR flux is discussed.

Laser-based irradiation apparatus and method to measure the functional dose-rate response of semiconductor devices

DOEpatents

Horn, Kevin M [Albuquerque, NM

2008-05-20

A broad-beam laser irradiation apparatus can measure the parametric or functional response of a semiconductor device to exposure to dose-rate equivalent infrared laser light. Comparisons of dose-rate response from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems can determine if aging has affected the device's overall functionality. The dependence of these changes on equivalent dose-rate pulse intensity and/or duration can be measured with the apparatus. The synchronized introduction of external electrical transients into the device under test can be used to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure while exposing the device to dose-rate equivalent infrared laser light.

Single dose systemic acetaminophen to improve patient reported quality of recovery after ambulatory segmental mastectomy: A prospective, randomized, double-blinded, placebo controlled, clinical trial.

PubMed

De Oliveira, Gildasio S; Rodes, Meghan E; Bialek, Jane; Kendall, Mark C; McCarthy, Robert J

2017-11-15

Few systemic drug interventions are efficacious to improve patient reported quality of recovery after ambulatory surgery. We aimed to evaluate whether a single dose systemic acetaminophen improve quality of recovery in female patients undergoing ambulatory breast surgery. We hypothesized that patients receiving a single dose systemic acetaminophen at the end of the surgical procedure would have a better global quality of postsurgical recovery compared to the ones receiving saline. The study was a prospective randomized double blinded, placebo controlled, clinical trial. Healthy female subjects were randomized to receive 1 g single dose systemic acetaminophen at the end of the surgery or the same volume of saline. The primary outcome was the Quality of Recovery 40 (QOR-40) questionnaire at 24 hours after surgery. Other data collected included opioid consumption and pain scores. Data were analyzed using group t tests and the Wilcoxon exact test. The association between opioid consumption and quality of recovery was evaluated using Spearman rho. P < .05 was used to reject the null hypothesis for the primary outcome. Seventy subjects were randomized and sixty-five completed the study. Patients' baseline characteristics and surgical factors were similar between the study groups. There was a clinically significant difference in the global QoR-40 scores between the acetaminophen and the saline groups, median (IQR) of 189 (183 to 194) and 183 (175 to 190), respectively, P = .01. In addition, there was an inverse relationship (Spearman's rho= -0.33) between oral opioid consumption at home (oral morphine equivalents) and 24 hour postoperative quality of recovery, P = .007. A single dose of systemic acetaminophen improves patient reported quality of recovery after ambulatory breast surgery. The use of systemic acetaminophen is an efficacious strategy to improve patient perceived quality of postsurgical recovery and analgesic outcomes after hospital discharge for ambulatory breast surgery. © 2017 Wiley Periodicals, Inc.

A randomised, single-blind, single-dose, three-arm, parallel-group study in healthy subjects to demonstrate pharmacokinetic equivalence of ABP 501 and adalimumab.

PubMed

Kaur, Primal; Chow, Vincent; Zhang, Nan; Moxness, Michael; Kaliyaperumal, Arunan; Markus, Richard

2017-03-01

To demonstrate pharmacokinetic (PK) similarity of biosimilar candidate ABP 501 relative to adalimumab reference product from the USA and European Union (EU) and evaluate safety, tolerability and immunogenicity of ABP 501. Randomised, single-blind, single-dose, three-arm, parallel-group study; healthy subjects were randomised to receive ABP 501 (n=67), adalimumab (USA) (n=69) or adalimumab (EU) (n=67) 40 mg subcutaneously. Primary end points were area under the serum concentration-time curve from time 0 extrapolated to infinity (AUC inf ) and the maximum observed concentration (C max ). Secondary end points included safety and immunogenicity. AUC inf and C max were similar across the three groups. Geometrical mean ratio (GMR) of AUC inf was 1.11 between ABP 501 and adalimumab (USA), and 1.04 between ABP 501 and adalimumab (EU). GMR of C max was 1.04 between ABP 501 and adalimumab (USA) and 0.96 between ABP 501 and adalimumab (EU). The 90% CIs for the GMRs of AUC inf and C max were within the prespecified standard PK equivalence criteria of 0.80 to 1.25. Treatment-related adverse events were mild to moderate and were reported for 35.8%, 24.6% and 41.8% of subjects in the ABP 501, adalimumab (USA) and adalimumab (EU) groups; incidence of antidrug antibodies (ADAbs) was similar among the study groups. Results of this study demonstrated PK similarity of ABP 501 with adalimumab (USA) and adalimumab (EU) after a single 40-mg subcutaneous injection. No new safety signals with ABP 501 were identified. The safety and tolerability of ABP 501 was similar to the reference products, and similar ADAb rates were observed across the three groups. EudraCT number 2012-000785-37; Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

LET spectra measurements from the STS-35 CPDs

NASA Technical Reports Server (NTRS)

1995-01-01

Linear energy transfer (LET) spectra derived form automated track analysis system (ATAS) track parameter measurements for crew passive dosimeters (CPD's) flown with the astronauts on STS-35 are plotted. The spread between the seven individual spectra is typical of past manual measurements of sets of CPD's. This difference is probably due to the cumulative net shielding variations experienced by the CPD's as the astronauts carrying them went about their activities on the Space Shuttle. The STS-35 mission was launched on Dec. 2, 1990, at 28.5 degrees inclination and 352-km altitude. This is somewhat higher than the nominal 300-km flights and the orbit intersects more of the high intensity trapped proton region in the South Atlantic Anomaly (SAA). However, in comparison with APD spectra measured on earlier lower altitude missions (STS-26, -29, -30, -32), the flux spectra are all roughly comparable. This may be due to the fact that the STS-35 mission took place close to solar maximum (Feb. 1990), or perhaps to shielding differences. The corresponding dose and dose equivalent spectra for this mission are shown. The effect of statistical fluctuations at the higher LET values, where track densities are small, is very noticeable. This results in an increased spread within the dose rate and dose equivalent rate spectra, as compared to the flux spectra. The contribution to dose and dose equivalent per measured track is much greater in the high LET region and the differences, though numerically small, are heavily weighted in the integral spectra. The optimum measurement and characterization of the high LET tails of the spectra represent an important part of the research into plastic nuclear track detector (PNTD) response. The integral flux, dose rate, dose equivalent rate and mission dose equivalent for the seven astronauts are also given.

Ambient dose equivalent and effective dose from scattered x-ray spectra in mammography for Mo/Mo, Mo/Rh and W/Rh anode/filter combinations.

PubMed

Künzel, R; Herdade, S B; Costa, P R; Terini, R A; Levenhagen, R S

2006-04-21

In this study, scattered x-ray distributions were produced by irradiating a tissue equivalent phantom under clinical mammographic conditions by using Mo/Mo, Mo/Rh and W/Rh anode/filter combinations, for 25 and 30 kV tube voltages. Energy spectra of the scattered x-rays have been measured with a Cd(0.9)Zn(0.1)Te (CZT) detector for scattering angles between 30 degrees and 165 degrees . Measurement and correction processes have been evaluated through the comparison between the values of the half-value layer (HVL) and air kerma calculated from the corrected spectra and measured with an ionization chamber in a nonclinical x-ray system with a W/Mo anode/filter combination. The shape of the corrected x-ray spectra measured in the nonclinical system was also compared with those calculated using semi-empirical models published in the literature. Scattered x-ray spectra measured in the clinical x-ray system have been characterized through the calculation of HVL and mean photon energy. Values of the air kerma, ambient dose equivalent and effective dose have been evaluated through the corrected x-ray spectra. Mean conversion coefficients relating the air kerma to the ambient dose equivalent and to the effective dose from the scattered beams for Mo/Mo, Mo/Rh and W/Rh anode/filter combinations were also evaluated. Results show that for the scattered radiation beams the ambient dose equivalent provides an overestimate of the effective dose by a factor of about 5 in the mammography energy range. These results can be used in the control of the dose limits around a clinical unit and in the calculation of more realistic protective shielding barriers in mammography.

Ambient Dose Equivalent measured at the Instituto Nacional de Cancerologia Department of Nuclear Medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avila, O.; Torres-Ulloa, C. L.; Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, AP 70-542, 04510, DF

2010-12-07

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerologia, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with {sup 137}Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrologia, to known {sup 137}Cs gamma radiation air kerma. Radionuclides considered for this study are {sup 131}I, {sup 18}F, {sup 67}Ga, {sup 99m}Tc, {sup 111}In, {sup 201}Tl and {sup 137}Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placedmore » during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with {sup 131}I and {sup 137}Cs. High dose values were found at the waste storage room, outside corridor of {sup 137}Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the {sup 137}Cs brachytherapy corridor is equal to (18.51{+-}0.02)x10{sup -3} mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05{+-}0.03)x10{sup -3} mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).« less

Depth dependence of absorbed dose, dose equivalent and linear energy transfer spectra of galactic and trapped particles in polyethylene and comparison with calculations of models

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Cucinotta, F. A.; Wilson, J. W. (Principal Investigator)

1998-01-01

A matched set of five tissue-equivalent proportional counters (TEPCs), embedded at the centers of 0 (bare), 3, 5, 8 and 12-inch-diameter polyethylene spheres, were flown on the Shuttle flight STS-81 (inclination 51.65 degrees, altitude approximately 400 km). The data obtained were separated into contributions from trapped protons and galactic cosmic radiation (GCR). From the measured linear energy transfer (LET) spectra, the absorbed dose and dose-equivalent rates were calculated. The results were compared to calculations made with the radiation transport model HZETRN/NUCFRG2, using the GCR free-space spectra, orbit-averaged geomagnetic transmission function and Shuttle shielding distributions. The comparison shows that the model fits the dose rates to a root mean square (rms) error of 5%, and dose-equivalent rates to an rms error of 10%. Fairly good agreement between the LET spectra was found; however, differences are seen at both low and high LET. These differences can be understood as due to the combined effects of chord-length variation and detector response function. These results rule out a number of radiation transport/nuclear fragmentation models. Similar comparisons of trapped-proton dose rates were made between calculations made with the proton transport model BRYNTRN using the AP-8 MIN trapped-proton model and Shuttle shielding distributions. The predictions of absorbed dose and dose-equivalent rates are fairly good. However, the prediction of the LET spectra below approximately 30 keV/microm shows the need to improve the AP-8 model. These results have strong implications for shielding requirements for an interplanetary manned mission.

Concept of proton radiography using energy resolved dose measurement.

PubMed

Bentefour, El H; Schnuerer, Roland; Lu, Hsiao-Ming

2016-08-21

Energy resolved dosimetry offers a potential path to single detector based proton imaging using scanned proton beams. This is because energy resolved dose functions encrypt the radiological depth at which the measurements are made. When a set of predetermined proton beams 'proton imaging field' are used to deliver a well determined dose distribution in a specific volume, then, at any given depth x of this volume, the behavior of the dose against the energies of the proton imaging field is unique and characterizes the depth x. This concept applies directly to proton therapy scanning delivery methods (pencil beam scanning and uniform scanning) and it can be extended to the proton therapy passive delivery methods (single and double scattering) if the delivery of the irradiation is time-controlled with a known time-energy relationship. To derive the water equivalent path length (WEPL) from the energy resolved dose measurement, one may proceed in two different ways. A first method is by matching the measured energy resolved dose function to a pre-established calibration database of the behavior of the energy resolved dose in water, measured over the entire range of radiological depths with at least 1 mm spatial resolution. This calibration database can also be made specific to the patient if computed using the patient x-CT data. A second method to determine the WEPL is by using the empirical relationships between the WEPL and the integral dose or the depth at 80% of the proximal fall off of the energy resolved dose functions in water. In this note, we establish the evidence of the fundamental relationship between the energy resolved dose and the WEPL at the depth of the measurement. Then, we illustrate this relationship with experimental data and discuss its imaging dynamic range for 230 MeV protons.

Out-of-field doses and neutron dose equivalents for electron beams from modern Varian and Elekta linear accelerators.

PubMed

Cardenas, Carlos E; Nitsch, Paige L; Kudchadker, Rajat J; Howell, Rebecca M; Kry, Stephen F

2016-07-08

Out-of-field doses from radiotherapy can cause harmful side effects or eventually lead to secondary cancers. Scattered doses outside the applicator field, neutron source strength values, and neutron dose equivalents have not been broadly investigated for high-energy electron beams. To better understand the extent of these exposures, we measured out-of-field dose characteristics of electron applicators for high-energy electron beams on two Varian 21iXs, a Varian TrueBeam, and an Elekta Versa HD operating at various energy levels. Out-of-field dose profiles and percent depth-dose curves were measured in a Wellhofer water phantom using a Farmer ion chamber. Neutron dose was assessed using a combination of moderator buckets and gold activation foils placed on the treatment couch at various locations in the patient plane on both the Varian 21iX and Elekta Versa HD linear accelerators. Our findings showed that out-of-field electron doses were highest for the highest electron energies. These doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. The Elekta linear accelerator had higher electron out-of-field doses than the Varian units examined, and the Elekta dose profiles exhibited a second dose peak about 20 to 30 cm from central-axis, which was found to be higher than typical out-of-field doses from photon beams. Electron doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. With respect to neutron dosimetry, Q values and neutron dose equivalents increased with electron beam energy. Neutron contamination from electron beams was found to be much lower than that from photon beams. Even though the neutron dose equivalent for electron beams represented a small portion of neutron doses observed under photon beams, neutron doses from electron beams may need to be considered for special cases.

Reward and Toxicity of Cocaine Metabolites Generated by Cocaine Hydrolase.

PubMed

Murthy, Vishakantha; Geng, Liyi; Gao, Yang; Zhang, Bin; Miller, Jordan D; Reyes, Santiago; Brimijoin, Stephen

2015-08-01

Butyrylcholinesterase (BChE) gene therapy is emerging as a promising concept for treatment of cocaine addiction. BChE levels after gene transfer can rise 1000-fold above those in untreated mice, making this enzyme the second most abundant plasma protein. For months or years, gene transfer of a BChE mutated into a cocaine hydrolase (CocH) can maintain enzyme levels that destroy cocaine within seconds after appearance in the blood stream, allowing little to reach the brain. Rapid enzyme action causes a sharp rise in plasma levels of two cocaine metabolites, benzoic acid (BA) and ecgonine methyl ester (EME), a smooth muscle relaxant that is mildly hypotensive and, at best, only weakly rewarding. The present study, utilizing Balb/c mice, tested reward effects and cardiovascular effects of administering EME and BA together at molar levels equivalent to those generated by a given dose of cocaine. Reward was evaluated by conditioned place preference. In this paradigm, cocaine (20 mg/kg) induced a robust positive response but the equivalent combined dose of EME + BA failed to induce either place preference or aversion. Likewise, mice that had undergone gene transfer with mouse CocH (mCocH) showed no place preference or aversion after repeated treatments with a near-lethal 80 mg/kg cocaine dose. Furthermore, a single administration of that same high cocaine dose failed to affect blood pressure as measured using the noninvasive tail-cuff method. These observations confirm that the drug metabolites generated after CocH gene transfer therapy are safe even after a dose of cocaine that would ordinarily be lethal.

Test of ring, eye lens and whole body dosemeters for the dose quantity Hp(3) to be used in interventional radiology

NASA Astrophysics Data System (ADS)

Szumska, A.; Budzanowski, M.; Kopeć, R.

2017-11-01

In its statement on tissue reactions approved on 21st April 2011, the International Commission on Radiological Protection (ICRP, 2012) reviewed its recommendation concerning the equivalent dose limit for the eye lens and reduced the dose limits for occupationally exposed persons to 20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv. This limit was approved and written down in the new EURATOM (European Atomic Energy Community) directive 2013/59 and in the IAEA (International Atomic Energy Agency) BSS (Basic Safety Standard) of July 2014. For that reason, the necessity to monitor the eye lens may become more important than it was before. However, specially dedicated dosemeters for the dose quantity Hp(3) are using very rarely. Commonly use are only whole body personal dosemeters for the personal dose equivalent quantities Hp(10) worn on the trunk and ring dosemeters worn on finger to measure the quantity Hp(0.07). Therefore, in this work it was investigated whether dosemeters from routine use calibrated in terms of Hp(10) and Hp(0.07) and worn on thyroid collar and protective apron could deliver similar results like dedicated eye lens dosemeter worn close to the eyes. The results show that the best method if dedicated eye lens dosimeters is not used is to measure doses in terms of Hp(0.07) on the thyroid collar (Pearson product, r=0.85). Obtained results shows also importance of proper localization of eye lens dosimeter (close to the eye, from side of the X-ray source).

SU-F-T-426: Measurement of Dose Enhancement Due to Backscatter From Modern Dental Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurwitz, M; Margalit, D; Williams, C

Purpose: High-density materials used in dental restoration can cause significant localized dose enhancement due to electron backscatter in head-and-neck radiotherapy, increasing the risk of mucositis. The materials used in prosthetic dentistry have evolved in the last decades from metal alloys to ceramics. We aim to determine the dose enhancement caused by backscatter from currently-used dental materials. Methods: Measurements were performed for three different dental materials: lithium disilicate (Li{sub 2}Si{sub 2}O{sub 5}), zirconium dioxide (ZrO{sub 2}), and gold alloy. Small thin squares (2×2×0.15 cm{sup 3}) of the material were fabricated, and placed into a phantom composed of tissue-equivalent material. The phantommore » was irradiated with a single 6 MV photon field. A thin-window parallel-plate ion chamber was used to measure the dose at varying distances from the proximal interface between the material and the plastic. Results: The dose enhancement at the interface between the high-density and tissue-equivalent materials, relative to a homogeneous phantom, was 54% for the gold alloy, 31% for ZrO{sub 2}, and 9% for Li{sub 2}Si{sub 2}O{sub 5}. This enhancement decreased rapidly with distance from the interface, falling to 11%, 5%, and 0.5%, respectively, 2 mm from the interface. Comparisons with the modeling of this effect in treatment planning systems are performed. Conclusion: While dose enhancement due to dental restoration is smaller with ceramic materials than with metal alloys, it can still be significant. A spacer of about 2–3 mm would be effective in reducing this enhancement, even for metal alloys.« less

Comparative pulmonary toxicological assessment of oil combustion particles following inhalation or instillation exposure.

PubMed

Costa, Daniel L; Lehmann, James R; Winsett, Darrell; Richards, Judy; Ledbetter, Allen D; Dreher, Kevin L

2006-05-01

Controversy persists regarding the validity of intratracheal instillation (IT) of particulate matter (PM) as a surrogate for inhalation exposure (IH) in rodents. Concerns center on dose, dose-rate, and distribution of material within the lung. Acute toxicity of a residual oil fly ash (ROFA) administered by IH was compared to those effects of a single IT bolus at an IH-equivalent dose. Male Sprague Dawley rats (60 days old) were exposed by nose-only IH to approximately 12 mg/m3 for 6 h. Inter-lobar dose distribution of ROFA, dissected immediately post exposure, was assayed by neutron activation. Vanadium and nickel were used as ROFA markers. IT administration of the IH-equivalent dose (110 microg) showed similar (<15%) interlobular distribution, with the exception of the inferior lobe dose (IT>IH approximately 25%). Evaluation of airway hyperreactivity (AHR), bronchoalveolar lavage fluid (BALF) constituents, and histopathology was conducted at 24, 48, and 96 h post exposure. AHR in the IH group was minimally (p > 0.05) affected by treatment, but was significantly increased ( approximately 40%) at both 24 and 48 h post IT. Inflammation in both groups, as measured by alterations in BALF protein, lactate dehydrogenase and neutrophils, was virtually identical at all time points. Alveolitis and bronchial inflammation/epithelial hypertrophy were prominent 24 h following IT, but not apparent after IH. Conversely, alveolar hemorrhage, congestion, and airway exudate were pronounced at 48 h post-IH but not remarkable in the IT group. Thus, IT-ROFA mimicked IH in terms of lobar distribution and injury biomarkers over 96 h, while morphological alterations and AHR appeared to be more dependent on the method of administration.

Bacterial extract (OM-85) with human-equivalent doses does not inhibit the development of asthma in a murine model.

PubMed

Rodrigues, A; Gualdi, L P; de Souza, R G; Vargas, M H M; Nuñez, N K; da Cunha, A A; Jones, M H; Pinto, L A; Stein, R T; Pitrez, P M

OM-85 is an immunostimulant bacterial lysate, which has been proven effective in reducing the number of lower airways infections. We investigated the efficacy of the bacterial lysate OM-85 in the primary prevention of a murine model of asthma. In the first phase of our study the animals received doses of 0.5μg, 5μg and 50μg of OM-85 through gavage for five days (days -10 to -6 of the protocol), 10 days prior to starting the sensitisation with ovalbumin (OVA), in order to evaluate the results of dose-response protocols. A single dose (5μg) was then chosen in order to verify in detail the effect of OM-85 on the pulmonary allergic response. Total/differential cells count and cytokine levels (IL-4, IL-5, IL-13 and IFN-γ) from bronchoalveolar lavage fluid (BALF), OVA-specific IgE levels from serum, lung function and lung histopathological analysis were evaluated. OM-85 did not reduce pulmonary eosinophilic response, regardless of the dose used. In the phase protocol using 5μg/animal of OM-85, no difference was shown among the groups studied, including total cell and eosinophil counts in BALF, serum OVA-specific IgE, lung histopathologic findings and lung resistance. However, OM-85 decreased IL-5 and IL-13 levels in BALF. OM-85, administered in early life in mice in human-equivalent doses, does not inhibit the development of allergic pulmonary response in mice. Copyright © 2016 SEICAP. Published by Elsevier España, S.L.U. All rights reserved.

Trial Evaluating Ambulatory Therapy of Travelers' Diarrhea (TrEAT TD) Study: A Randomized Controlled Trial Comparing 3 Single-Dose Antibiotic Regimens With Loperamide.

PubMed

Riddle, Mark S; Connor, Patrick; Fraser, Jamie; Porter, Chad K; Swierczewski, Brett; Hutley, Emma J; Danboise, Brook; Simons, Mark P; Hulseberg, Christine; Lalani, Tahaniyat; Gutierrez, Ramiro L; Tribble, David R

2017-11-29

Recommended treatment for travelers' diarrhea includes the combination of an antibiotic, usually a fluoroquinolone or azithromycin, and loperamide for rapid resolution of symptoms. However, adverse events, postdose nausea with high-dose azithromycin, effectiveness of single-dose rifaximin, and emerging resistance to front-line agents are evidence gaps underlying current recommendations. A randomized, double-blind trial was conducted in 4 countries (Afghanistan, Djibouti, Kenya, and Honduras) between September 2012 and July 2015. US and UK service members with acute watery diarrhea were randomized and received single-dose azithromycin (500 mg; 106 persons), levofloxacin (500 mg; 111 persons), or rifaximin (1650 mg; 107 persons), in combination with loperamide (labeled dosing). The efficacy outcomes included clinical cure at 24 hours and time to last unformed stool. Clinical cure at 24 hours occurred in 81.4%, 78.3%, and 74.8% of the levofloxacin, azithromycin, and rifaximin arms, respectively. Compared with levofloxacin, azithromycin was not inferior (P = .01). Noninferiority could not be shown with rifaximin (P = .07). At 48 and 72 hours, efficacy among regimens was equivalent (approximately 91% at 48 and 96% at 72 hours). The median time to last unformed stool did not differ between treatment arms (azithromycin, 3.8 hours; levofloxacin, 6.4 hours; rifaximin, 5.6 hours). Treatment failures were uncommon (3.8%, 4.4%, and 1.9% in azithromycin, levofloxacin, and rifaximin arms, respectively) (P = .55). There were no differences between treatment arms with postdose nausea, vomiting, or other adverse events. Single-dose azithromycin, levofloxacin, and rifaximin with loperamide were comparable for treatment of acute watery diarrhea. NCT01618591. Published by Oxford University Press for the Infectious Diseases Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

MEASUREMENT OF RADIATION DOSES TO THE EYE LENS DURING ORTHOPEDIC SURGERY USING AN C-ARM X-RAY SYSTEM.

PubMed

Suzuki, Akira; Matsubara, Kosuke; Sasa, Yuko

2018-04-01

The present study aimed to determine doses delivered to the eye lenses of surgeons while using the inverted-C-arm technique and the protective effect of leaded spectacles during orthopedic surgery. The kerma in air was measured at five positions on leaded glasses positioned near the eye lens and on the neck using small optically stimulated luminescence (OSL) dosemeters. The lens equivalent dose was also measured at the neck using an OSL dosemeter. The maximum equivalent dose to the eye lens and the maximum kerma were 0.8 mSv/month and 0.66 mGy/month, respectively. The leaded glasses reduced the exposure by ~60%. Even if the surgeons are exposed to the maximum dose of X-ray radiation for 5 years, the equivalent doses to the eye lens will not exceed the present limit recommended by the ICRP.

Dental radiography: tooth enamel EPR dose assessment from Rando phantom measurements

NASA Astrophysics Data System (ADS)

Aragno, D.; Fattibene, P.; Onori, S.; Aragno, D.; Fattibene, P.

2000-09-01

Electron paramagnetic resonance dosimetry of tooth enamel is now established as a suitable method for individual dose reconstruction following radiation accidents. The accuracy of the method is limited by some confounding factors, among which is the dose received due to medical x-ray irradiation. In the present paper the EPR response of tooth enamel to endoral examination was experimentally evaluated using an anthropomorphic phantom. The dose to enamel for a single exposure of a typical dental examination performed with a new x-ray generation unit working at 65 kVp gave rise to a CO2- signal of intensity similar to that induced by a dose of about 2 mGy of 60Co. EPR measurements were performed on the entire tooth with no attempt to separate buccal and lingual components. Also the dose to enamel for an orthopantomography exam was estimated. It was derived from TLD measurements as equivalent to 0.2 mGy of 60Co. In view of application to risk assessment analysis, in the present work the value for the ratio of the reference dose at the phantom surface measured with TLD to the dose at the tooth measured with EPR was determined.

Skeletal dosimetry for external exposure to photons based on µCT images of spongiosa from different bone sites

NASA Astrophysics Data System (ADS)

Kramer, R.; Khoury, H. J.; Vieira, J. W.; Kawrakow, I.

2007-11-01

Micro computed tomography (µCT) images of human spongiosa have recently been used for skeletal dosimetry with respect to external exposure to photon radiation. In this previous investigation, the calculation of equivalent dose to the red bone marrow (RBM) and to the bone surface cells (BSC) was based on five different clusters of micro matrices derived from µCT images of vertebrae, and the BSC equivalent dose for 10 µm thickness of the BSC layer was determined using an extrapolation method. The purpose of this study is to extend the earlier investigation by using µCT images from eight different bone sites and by introducing an algorithm for the direct calculation of the BSC equivalent dose with sub-micro voxel resolution. The results show that for given trabecular bone volume fractions (TBVFs) the whole-body RBM equivalent dose does not depend on bone site-specific properties or imaging parameters. However, this study demonstrates that apart from the TBVF and the BSC layer thickness, the BSC equivalent dose additionally depends on a so-called trabecular bone structure (TBS) effect, i.e. that the contribution of photo-electrons released in trabecular bone to the BSC equivalent dose also depends on the bone site-specific structure of the trabeculae. For a given bone site, the TBS effect is also a function of the thickness of the BSC layer, and it could be shown that this effect would disappear almost completely, should the BSC layer thickness be raised from 10 to 50 µm, according to new radiobiological findings.

Neutrons in active proton therapy: Parameterization of dose and dose equivalent.

PubMed

Schneider, Uwe; Hälg, Roger A; Lomax, Tony

2017-06-01

One of the essential elements of an epidemiological study to decide if proton therapy may be associated with increased or decreased subsequent malignancies compared to photon therapy is an ability to estimate all doses to non-target tissues, including neutron dose. This work therefore aims to predict for patients using proton pencil beam scanning the spatially localized neutron doses and dose equivalents. The proton pencil beam of Gantry 1 at the Paul Scherrer Institute (PSI) was Monte Carlo simulated using GEANT. Based on the simulated neutron dose and neutron spectra an analytical mechanistic dose model was developed. The pencil beam algorithm used for treatment planning at PSI has been extended using the developed model in order to calculate the neutron component of the delivered dose distribution for each treated patient. The neutron dose was estimated for two patient example cases. The analytical neutron dose model represents the three-dimensional Monte Carlo simulated dose distribution up to 85cm from the proton pencil beam with a satisfying precision. The root mean square error between Monte Carlo simulation and model is largest for 138MeV protons and is 19% and 20% for dose and dose equivalent, respectively. The model was successfully integrated into the PSI treatment planning system. In average the neutron dose is increased by 10% or 65% when using 160MeV or 177MeV instead of 138MeV. For the neutron dose equivalent the increase is 8% and 57%. The presented neutron dose calculations allow for estimates of dose that can be used in subsequent epidemiological studies or, should the need arise, to estimate the neutron dose at any point where a subsequent secondary tumour may occur. It was found that the neutron dose to the patient is heavily increased with proton energy. Copyright © 2016. Published by Elsevier GmbH.

Medical and occupational dose reduction in pediatric barium meal procedures

NASA Astrophysics Data System (ADS)

Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Ledesma, J. A.; Legnani, A.; Bunick, A. P.; Sauzen, J.; Yagui, A.; Vosiak, P.

2017-11-01

Doses received in pediatric Barium Meal procedure can be rather high. It is possible to reduce dose values following the recommendations of the European Communities (EC) and the International Commission on Radiological Protection (ICRP). In the present work, the modifications of radiographic techniques made in a Brazilian hospital according to the EC and the ICRP recommendations and their influence on medical and occupational exposure are reported. The procedures of 49 patients before and 44 after the optimization were studied and air kerma-area product (PK,A) values and the effective doses were evaluated. The occupational equivalent doses were measured next to the eyes, under the thyroid shield and on each hand of both professionals who remained inside the examination room. The implemented modifications reduced by 70% and 60% the PK,A and the patient effective dose, respectively. The obtained dose values are lower than approximately 75% of the results from similar studies. The occupational annual equivalent doses for all studied organs became lower than the limits set by the ICRP. The equivalent doses in one examination were on average below than 75% of similar studies.

Current clinical use of reteplase for thrombolysis. A pharmacokinetic-pharmacodynamic perspective.

PubMed

Martin, U; Kaufmann, B; Neugebauer, G

1999-04-01

Clinical evaluation of a new thrombolytic agent should start with a dose that provides adequate efficacy and has an acceptably low bleeding risk; this results in a narrow therapeutic window at the upper end of the dose-response curve. Angiographic patency of the infarct-related artery is still the clinical surrogate end-point for mortality in phase II dose-ranging studies. There is experimental and clinical evidence that the area under the concentration-time curve (AUC) for plasminogenolytic activity of a thrombolytic agent is positively correlated with patency of the infarct-related artery. Dose-ranging studies of the novel recombinant plasminogen activator reteplase in healthy volunteers enabled computation of a linear regression curve by which a clinical starting dose could be calculated for an adapted target AUC that would be clinically effective. Pharmacokinetic analysis also revealed that the half-life of reteplase is 4 times longer than that of the reference thrombolytic alteplase, thus allowing bolus injection. The suggested single bolus starting dose of 10U was supported by results from studies in a canine model of coronary thrombolysis. The feedback of insufficiently high patency rates compared with the increased efficacy of front-loaded and accelerated alteplase demanded optimisation strategies for reteplase. Animal experiments suggested that a double bolus regimen of reteplase would be preferable to doubling the single bolus dose. Pharmacokinetic modelling suggested a time interval of 30 min between the 2 bolus injections. Selection of the tested double bolus regimens was conservative and empirical. First, the previously tested single bolus of 15U was divided to 10 + 5U; secondly, the second bolus dose was increased to 10U. This strategy proved to be successful. The current dosage recommendation for reteplase is a double bolus intravenous injection of 10 + 10U, each over 2 min, 30 min apart. This produces a reduction in mortality in patients with acute myocardial infarction that is equivalent to that produced by front-loaded and accelerated infusion of alteplase.

Biomagnification of cycad neurotoxins in flying foxes: implications for ALS-PDC in Guam.

PubMed

Banack, Sandra Anne; Cox, Paul Alan

2003-08-12

Beta-methylamino-L-alanine (BMAA) occurs in higher levels in museum specimens of the Guamanian flying fox than in the cycad seeds the flying foxes feed on, confirming the hypothesis that cycad neurotoxins are biomagnified within the Guam ecosystem. Consumption of a single flying fox may have resulted in an equivalent BMAA dose obtained from eating 174 to 1,014 kg of processed cycad flour. Traditional feasting on flying foxes may be related to the prevalence of neuropathologic disease in Guam.

Dose-equivalent neutron dosimeter

DOEpatents

Griffith, R.V.; Hankins, D.E.; Tomasino, L.; Gomaa, M.A.M.

1981-01-07

A neutron dosimeter is disclosed which provides a single measurement indicating the amount of potential biological damage resulting from the neutron exposure of the wearer, for a wide range of neutron energies. The dosimeter includes a detecting sheet of track etch detecting material such as a carbonate plastic, for detecting higher energy neutrons, and a radiator layer contaning conversion material such as /sup 6/Li and /sup 10/B lying adjacent to the detecting sheet for converting moderate energy neutrons to alpha particles that produce tracks in the adjacent detecting sheet.

Dose assessment for the fetus considering scattered and secondary radiation from photon and proton therapy when treating a brain tumor of the mother

NASA Astrophysics Data System (ADS)

Geng, Changran; Moteabbed, Maryam; Seco, Joao; Gao, Yiming; Xu, X. George; Ramos-Méndez, José; Faddegon, Bruce; Paganetti, Harald

2016-01-01

The goal of this work was to determine the scattered photon dose and secondary neutron dose and resulting risk for the sensitive fetus from photon and proton radiotherapy when treating a brain tumor during pregnancy. Anthropomorphic pregnancy phantoms with three stages (3-, 6-, 9-month) based on ICRP reference parameters were implemented in Monte Carlo platform TOPAS, to evaluate the scattered dose and secondary neutron dose and dose equivalent. To evaluate the dose equivalent, dose averaged quality factors were considered for neutrons. This study compared three treatment modalities: passive scattering and pencil beam scanning proton therapy (PPT and PBS) and 6-MV 3D conformal photon therapy. The results show that, for 3D conformal photon therapy, the scattered photon dose equivalent to the fetal body increases from 0.011 to 0.030 mSv per treatment Gy with increasing stage of gestation. For PBS, the neutron dose equivalent to the fetal body was significantly lower, i.e. increasing from 1.5  ×  10-3 to 2.5  ×  10-3 mSv per treatment Gy with increasing stage of gestation. For PPT, the neutron dose equivalent of the fetus decreases from 0.17 to 0.13 mSv per treatment Gy with the growing fetus. The ratios of dose equivalents to the fetus for a 52.2 Gy(RBE) course of radiation therapy to a typical CT scan of the mother’s head ranged from 3.4-4.4 for PBS, 30-41 for 3D conformal photon therapy and 180-500 for PPT, respectively. The attained dose to a fetus from the three modalities is far lower than the thresholds of malformation, severe mental retardation and lethal death. The childhood cancer excessive absolute risk was estimated using a linear no-threshold dose-response relationship. The risk would be 1.0 (95% CI: 0.6, 1.6) and 0.1 (95% CI:  -0.01, 0.52) in 105 for the 9-month fetus for PBS with a prescribed dose of 52.2 Gy(RBE). The increased risks for PPT and photon therapy are about two and one orders of magnitude larger than that for PBS, respectively. We can conclude that a pregnant woman with a brain tumor could be treated with pencil beam scanning with acceptable risks to the fetus.

Captopril and losartan for mitigation of renal injury caused by single-dose total-body irradiation.

PubMed

Moulder, John E; Cohen, Eric P; Fish, Brian L

2011-01-01

It is known that angiotensin converting enzyme inhibitors (ACEIs) and angiotensin II type-1 receptor blockers (ARBs) can be used to mitigate radiation-induced renal injury. However, for a variety of reasons, these previous results are not directly applicable to the development of agents for the mitigation of injuries caused by terrorism-related radiation exposure. As part of an effort to develop an animal model that would fit the requirements of the U.S. Food and Drug Administration (FDA) "Animal Efficacy Rule", we designed new studies which used an FDA-approved ACEI (captopril) or an FDA-approved ARB (losartan, Cozaar®) started 10 days after a single total-body irradiation (TBI) at drug doses that are equivalent (on a g/m(2)/day basis) to the doses prescribed to humans. Captopril and losartan were equally effective as mitigators, with DMFs of 1.23 and 1.21, respectively, for delaying renal failure. These studies show that radiation nephropathy in a realistic rodent model can be mitigated with relevant doses of FDA-approved agents. This lays the necessary groundwork for pivotal rodent studies under the FDA Animal Efficacy Rule and provides an outline of how the FDA-required large-animal studies could be designed.

Captopril and Losartan for Mitigation of Renal Injury Caused by Single-Dose Total-Body Irradiation

PubMed Central

Moulder, John E.; Cohen, Eric P.; Fish, Brian L.

2011-01-01

It is known that angiotensin converting enzyme inhibitors (ACEIs) and angiotensin II type-1 receptor blockers (ARBs) can be used to mitigate radiation-induced renal injury. However, for a variety of reasons, these previous results are not directly applicable to the development of agents for the mitigation of injuries caused by terrorism-related radiation exposure. As part of an effort to develop an animal model that would fit the requirements of the U.S. Food and Drug Administration (FDA) “Animal Efficacy Rule”, we designed new studies which used an FDA-approved ACEI (captopril) or an FDA-approved ARB (losartan, Cozaar®) started 10 days after a single total-body irradiation (TBI) at drug doses that are equivalent (on a g/m2/day basis) to the doses prescribed to humans. Captopril and losartan were equally effective as mitigators, with DMFs of 1.23 and 1.21, respectively, for delaying renal failure. These studies show that radiation nephropathy in a realistic rodent model can be mitigated with relevant doses of FDA-approved agents. This lays the necessary groundwork for pivotal rodent studies under the FDA Animal Efficacy Rule and provides an outline of how the FDA-required large-animal studies could be designed. PMID:21175344

Systemic effects of H2S inhalation at human equivalent dose of pathologic halitosis on rats.

PubMed

Yalçın Yeler, Defne; Aydin, Murat; Gül, Mehmet; Hocaoğlu, Turgay; Özdemir, Hakan; Koraltan, Melike

2017-10-01

Halitosis is composed by hundreds of toxic gases. It is still not clear whether halitosis gases self-inhaled by halitosis patients cause side effects. The aim of the study was to investigate the effect of H 2 S inhalation at a low concentration (human equivalent dose of pathologic halitosis) on rats. The threshold level of pathologic halitosis perceived by humans at 250 ppb of H 2 S was converted to rat equivalent concentration (4.15 ppm). In the experimental group, 8 rats were exposed to H 2 S via continuous inhalation but not the control rats. After 50 days, blood parameters were measured and tissue samples were obtained from the brain, kidney and liver and examined histopathologically to determine any systemic effect. While aspartate transaminase, creatine kinase-MB and lactate dehydrogenase levels were found to be significantly elevated, carbondioxide and alkaline phosphatase were decreased in experimental rats. Other blood parameters were not changed significantly. Experimental rats lost weight and became anxious. Histopathological examination showed mononuclear inflammatory cell invasion in the portal areas, nuclear glycogen vacuoles in the parenchymal area, single-cell necrosis in a few foci, clear expansion in the central hepatic vein and sinusoids, hyperplasia in Kupffer cells and potential fibrous tissue expansion in the portal areas in the experimental rats. However, no considerable histologic damage was observed in the brain and kidney specimens. It can be concluded that H 2 S inhalation equivalent to pathologic halitosis producing level in humans may lead to systemic effects, particularly heart or liver damage in rats.

Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions.

PubMed

Straume, T; Braby, L A; Borak, T B; Lusby, T; Warner, D W; Perez-Nunez, D

2015-10-01

Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of yD (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with g rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h(-1). Measurements of yD for 200 MeV n(-1) carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%.

Compact Tissue-equivalent Proportional Counter for Deep Space Human Missions

PubMed Central

Straume, T.; Braby, L.A.; Borak, T.B.; Lusby, T.; Warner, D.W.; Perez-Nunez, D.

2015-01-01

Abstract Effects on human health from the complex radiation environment in deep space have not been measured and can only be simulated here on Earth using experimental systems and beams of radiations produced by accelerators, usually one beam at a time. This makes it particularly important to develop instruments that can be used on deep-space missions to measure quantities that are known to be relatable to the biological effectiveness of space radiation. Tissue-equivalent proportional counters (TEPCs) are such instruments. Unfortunately, present TEPCs are too large and power intensive to be used beyond low Earth orbit (LEO). Here, the authors describe a prototype of a compact TEPC designed for deep space applications with the capability to detect both ambient galactic cosmic rays and intense solar particle event radiation. The device employs an approach that permits real-time determination of (and thus quality factor) using a single detector. This was accomplished by assigning sequential sampling intervals as detectors “1” and “2” and requiring the intervals to be brief compared to the change in dose rate. Tests with γ rays show that the prototype instrument maintains linear response over the wide dose-rate range expected in space with an accuracy of better than 5% for dose rates above 3 mGy h−1. Measurements of for 200 MeV n−1 carbon ions were better than 10%. Limited tests with fission spectrum neutrons show absorbed dose-rate accuracy better than 15%. PMID:26313585

Computer simulations and models for the performance characteristics of spectrally equivalent X-ray beams in medical diagnostic radiology

PubMed Central

Okunade, Akintunde A.

2007-01-01

In order to achieve uniformity in radiological imaging, it is recommended that the concept of equivalence in shape (quality) and size (quantity) of clinical Xray beams should be used for carrying out the comparative evaluation of image and patient dose. When used under the same irradiation geometry, X-ray beams that are strictly or relatively equivalent in terms of shape and size will produce identical or relatively identical image quality and patient dose. Simple mathematical models and software program EQSPECT.FOR were developed for the comparative evaluation of the performance characteristics in terms of contrast (C), contrast to noise ratio (CNR) and figure-of-merit (FOM = CNR2/DOSE) for spectrally equivalent beams transmitted through filter materials referred to as conventional and k-edged. At the same value of operating potential (kVp), results show that spectrally equivalent beam transmitted through conventional filter with higher atomic number (Z-value) in comparison with that transmitted through conventional filter with lower Z-value resulted in the same value of C and FOM. However, in comparison with the spectrally equivalent beam transmitted through filter of lower Z-value, the beam through filter of higher Z-value produced higher value of CNR and DOSE at equal tube loading (mAs) and kVp. Under the condition of equivalence of spectrum, at scaled (or reduced) tube loading and same kVp, filter materials of higher Z-value can produce the same values of C, CNR, DOSE and FOM as filter materials of lower Z-value. Unlike the case of comparison of spectrally equivalent beam transmitted through one conventional filter and that through another conventional filter, it is not possible to derive simple mathematical formulations for the relative performance of spectrally equivalent beam transmitted through a given conventional filter material and that through kedge filter material. PMID:21224928

High energy neutron dosimeter

DOEpatents

Rai, K.S.F.

1994-01-11

A device for measuring dose equivalents in neutron radiation fields is described. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning. 2 figures.

Calculation of Dose, Dose Equivalent, and Relative Biological Effectiveness for High Charge and Energy Ion Beams

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Reginatto, M.; Hajnal, F.; Chun, S. Y.

1995-01-01

The Green's function for the transport of ions of high charge and energy is utilized with a nuclear fragmentation database to evaluate dose, dose equivalent, and RBE for C3H1OT1/2 cell survival and neoplastic transformation as a function of depth in soft tissue. Such evaluations are useful to estimates of biological risk for high altitude aircraft, space operations, accelerator operations, and biomedical applications.

Calculation of dose, dose equivalent, and relative biological effectiveness for high charge and energy ion beams

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Chun, S. Y.; Reginatto, M.; Hajnal, F.

1995-01-01

The Green's function for the transport of ions of high charge and energy is utilized with a nuclear fragmentation database to evaluate dose, dose equivalent, and RBE for C3H10T1/2 cell survival and neo-plastic transformation as function of depth in soft tissue. Such evaluations are useful to estimates of biological risk for high altitude aircraft, space operations, accelerator operations, and biomedical application.

Radiation measurements and doses at SST altitudes

NASA Technical Reports Server (NTRS)

Foelsche, T.

1972-01-01

Radiation components and dose equivalents due to galactic and solar cosmic rays in the high atmosphere, especially at SST altitudes, are presented. The dose equivalent rate for the flight personnel flying 500 hours per year in cruise altitudes of 60,000-65,000 feet (18-19.5 km) in high magnetic latitudes is about 0.75-1.0 rem per year averaged over the solar cycle, or about 15-20 percent of the maximum permissible dose rate.

Open-Label Single-Sequence Crossover Study Evaluating Pharmacokinetics, Efficacy, and Safety of Once-Daily Dosing of Nitisinone in Patients with Hereditary Tyrosinemia Type 1.

PubMed

Guffon, Nathalie; Bröijersén, Anders; Palmgren, Ingrid; Rudebeck, Mattias; Olsson, Birgitta

2018-01-01

Although nitisinone is successfully used to treat hereditary tyrosinemia type 1 (HT-1) with the recommended twice-daily dosing, data describing a long half-life motivate less frequent dosing. Therefore, in agreement with the Pharmacovigilance Risk Assessment Committee at the European Medicines Agency, this study was performed to investigate the switch to once-daily dosing. This open-label, non-randomized, single-sequence crossover study evaluated the pharmacokinetics, efficacy, and safety of once-daily compared to twice-daily dosing of nitisinone in patients with HT-1 (NCT02323529). Well-controlled patients of <2, 2 to <12, 12 to <18, and ≥18 years of age who were on twice-daily dosing were eligible for participation. Nitisinone and succinylacetone levels were determined from dry blood spots by tandem mass spectrometry. The primary endpoint was C min of nitisinone after ≥4 weeks of treatment on each dosing regimen. Secondary objectives were evaluation of efficacy and safety during each dosing regimen. In total, 19 patients were enrolled and 17 included in the per-protocol analysis set. The mean (SD) nitisinone C min decreased by 23%, from 26.4 (10.2) to 21.2 (9.9) μmol/L in dry blood spot samples (not equivalent to plasma concentrations), when patients switched from twice- to once-daily dosing. There was no apparent age- or bodyweight-related trend in the degree of C min decrease. No patient had quantifiable succinylacetone levels during the once-daily treatment period, indicating efficacious treatment. All adverse events were mild or moderate and judged unrelated to nitisinone. The switch to once-daily treatment with nitisinone appeared efficacious and safe in the treatment of patients with HT-1.

The leaded apron revisited: does it reduce gonadal radiation dose in dental radiology?

PubMed

Wood, R E; Harris, A M; van der Merwe, E J; Nortjé, C J

1991-05-01

A tissue-equivalent anthropomorphic human phantom was used with a lithium fluoride thermoluminescent dosimetry system to evaluate the radiation absorbed dose to the ovarian and testicular region during dental radiologic procedures. Measurements were made with and without personal lead shielding devices consisting of thyroid collar and apron of 0.25 mm lead thickness equivalence. The radiation absorbed dose with or without lead shielding did not differ significantly from control dosimeters in vertex occlusal and periapical views (p greater than 0.05). Personal lead shielding devices did reduce gonadal dose in the case of accidental exposure (p less than 0.05). A leaded apron of 0.25 mm lead thickness equivalent was permeable to radiation in direct exposure testing.

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

10 CFR 835.205 - Determination of compliance for non-uniform exposure of the skin.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 100 cm 2 or more. The non-uniform equivalent dose received during the year shall be averaged over the... irradiated is 10 cm 2 or more, but is less than 100 cm 2. The non-uniform equivalent dose (H) to the... less than 0.1 be used. (3) Area of skin irradiated is less than 10 cm 2. The non-uniform equivalent...

Calculation of Absorbed Dose in Target Tissue and Equivalent Dose in Sensitive Tissues of Patients Treated by BNCT Using MCNP4C

NASA Astrophysics Data System (ADS)

Zamani, M.; Kasesaz, Y.; Khalafi, H.; Pooya, S. M. Hosseini

Boron Neutron Capture Therapy (BNCT) is used for treatment of many diseases, including brain tumors, in many medical centers. In this method, a target area (e.g., head of patient) is irradiated by some optimized and suitable neutron fields such as research nuclear reactors. Aiming at protection of healthy tissues which are located in the vicinity of irradiated tissue, and based on the ALARA principle, it is required to prevent unnecessary exposure of these vital organs. In this study, by using numerical simulation method (MCNP4C Code), the absorbed dose in target tissue and the equiavalent dose in different sensitive tissues of a patiant treated by BNCT, are calculated. For this purpose, we have used the parameters of MIRD Standard Phantom. Equiavelent dose in 11 sensitive organs, located in the vicinity of target, and total equivalent dose in whole body, have been calculated. The results show that the absorbed dose in tumor and normal tissue of brain equal to 30.35 Gy and 0.19 Gy, respectively. Also, total equivalent dose in 11 sensitive organs, other than tumor and normal tissue of brain, is equal to 14 mGy. The maximum equivalent doses in organs, other than brain and tumor, appear to the tissues of lungs and thyroid and are equal to 7.35 mSv and 3.00 mSv, respectively.

Eye lens dose correlations with personal dose equivalent and patient exposure in paediatric interventional cardiology performed with a fluoroscopic biplane system.

PubMed

Alejo, L; Koren, C; Corredoira, E; Sánchez, F; Bayón, J; Serrada, A; Guibelalde, E

2017-04-01

To analyse the correlations between the eye lens dose estimates performed with dosimeters placed next to the eyes of paediatric interventional cardiologists working with a biplane system, the personal dose equivalent measured on the thorax and the patient dose. The eye lens dose was estimated in terms of H p (0.07) on a monthly basis, placing optically stimulated luminescence dosimeters (OSLDs) on goggles. The H p (0.07) personal dose equivalent was measured over aprons with whole-body OSLDs. Data on patient dose as recorded by the kerma-area product (P KA ) were collected using an automatic dose management system. The 2 paediatric cardiologists working in the facility were involved in the study, and 222 interventions in a 1-year period were evaluated. The ceiling-suspended screen was often disregarded during interventions. The annual eye lens doses estimated on goggles were 4.13±0.93 and 4.98±1.28mSv. Over the aprons, the doses obtained were 10.83±0.99 and 11.97±1.44mSv. The correlation between the goggles and the apron dose was R 2 =0.89, with a ratio of 0.38. The correlation with the patient dose was R 2 =0.40, with a ratio of 1.79μSvGy -1 cm -2 . The dose per procedure obtained over the aprons was 102±16μSv, and on goggles 40±9μSv. The eye lens dose normalized to P KA was 2.21±0.58μSvGy -1 cm -2 . Measurements of personal dose equivalent over the paediatric cardiologist's apron are useful to estimate eye lens dose levels if no radiation protection devices are typically used. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A critical point: the problems associated with the variety of criteria to quantify the antioxidant capacity.

PubMed

Prieto, M A; Vázquez, J A; Murado, M A

2014-06-18

The oxidant action implies interfering in an autocatalytic process, in which no less than five chemical species are present (oxygen, oxidizable substrate, radicals, antioxidants, and oxidation products); furthermore, reactions of first and second order can take place, and interactions can occur, at several levels of the process. The common and incorrect practice is to use the single-time dose-response of an established antioxidant as a calibration curve to compute the equivalent antioxidant capacity of a sample, which is only tested at one single time-dose, assuming too many false aspects as true. Its use is unreasonable, given the availability of computational applications and instrumental equipment that, combined, provide the adequate tools to work with different variables in nonlinear models. The evaluation of the dose-time dependency of the response of the β-carotene method as a case study, using the combination of strong quantification procedures and a high amount of results with lower experimental error (applying microplate readers), reveals the lack of meaning of single-time criteria. Also, it demonstrates that, in most of the reactions, the time-dependent response in the oxidation process is inherently nonlinear and should not be standardized at one single time, because it would lead to unreliable results, hiding the real aspects of the response. In food matrices, the application of single-time criteria causes deficiencies in the control of the antioxidant content. Therefore, it is logical that, in the past decade, researchers have claimed consensus to increase the determination and effectiveness of antioxidant responses.

Comparison of fluence-to-dose conversion coefficients for deuterons, tritons and helions.

PubMed

Copeland, Kyle; Friedberg, Wallace; Sato, Tatsuhiko; Niita, Koji

2012-02-01

Secondary radiation in aircraft and spacecraft includes deuterons, tritons and helions. Two sets of fluence-to-effective dose conversion coefficients for isotropic exposure to these particles were compared: one used the particle and heavy ion transport code system (PHITS) radiation transport code coupled with the International Commission on Radiological Protection (ICRP) reference phantoms (PHITS-ICRP) and the other the Monte Carlo N-Particle eXtended (MCNPX) radiation transport code coupled with modified BodyBuilder™ phantoms (MCNPX-BB). Also, two sets of fluence-to-effective dose equivalent conversion coefficients calculated using the PHITS-ICRP combination were compared: one used quality factors based on linear energy transfer; the other used quality factors based on lineal energy (y). Finally, PHITS-ICRP effective dose coefficients were compared with PHITS-ICRP effective dose equivalent coefficients. The PHITS-ICRP and MCNPX-BB effective dose coefficients were similar, except at high energies, where MCNPX-BB coefficients were higher. For helions, at most energies effective dose coefficients were much greater than effective dose equivalent coefficients. For deuterons and tritons, coefficients were similar when their radiation weighting factor was set to 2.

Assessment of radiation doses from residential smoke detectors that contain americium-241

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Donnell, F.R.; Etnier, E.L.; Holton, G.A.

1981-10-01

External dose equivalents and internal dose commitments were estimated for individuals and populations from annual distribution, use, and disposal of 10 million ionization chamber smoke detectors that contain 110 kBq (3 ..mu..Ci) americium-241 each. Under exposure scenarios developed for normal distribution, use, and disposal using the best available information, annual external dose equivalents to average individuals were estimated to range from 4 fSv (0.4 prem) to 20 nSv (2 ..mu..rem) for total body and from 7 fSv to 40 nSv for bone. Internal dose commitments to individuals under post disposal scenarios were estimated to range from 0.006 to 80 ..mu..Svmore » (0.0006 to 8 mrem) to total body and from 0.06 to 800 ..mu..Sv to bone. The total collective dose (the sum of external dose equivalents and 50-year internal dose commitments) for all individuals involved with distribution, use, or disposal of 10 million smoke detectors was estimated to be about 0.38 person-Sv (38 person-rem) to total body and 00 ft/sup 2/).« less

Dimensional isotropy of 6H and 3C SiC under neutron irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snead, Lance L.; Katoh, Yutai; Koyanagi, Takaaki

2016-01-16

This investigation experimentally determines the as-irradiated crystal axes dimensional change of the common polytypes of SiC considered for nuclear application. Single crystal α-SiC (6H), β-SiC (3C), CVD β-SiC, and single crystal Si have been neutron irradiated near 60 °C from 2 × 10 23 to 2 × 10 26 n/m 2 (E > 0.1 MeV), or about 0.02–20 dpa, in order to study the effect of irradiation on bulk swelling and strain along independent crystalline axes. Single crystal, powder diffractometry and density measurement have been carried out. For all neutron doses where the samples remained crystalline all SiC materials demonstratedmore » equivalent swelling behavior. Moreover the 6H–SiC expanded isotropically. The magnitude of the swelling followed a ~0.77 power law against dose consistent with a microstructure evolution driven by single interstitial (carbon) mobility. Extraordinarily large ~7.8% volume expansion in SiC was observed prior to amorphization. Above ~0.9 × 10 25 n/m 2 (E > 0.1 MeV) all SiC materials became amorphous with an identical swelling: a 11.7% volume expansion, lowering the density to 2.84 g/cm 3. As a result, the as-amorphized density was the same at the 2 × 10 25 and 2 × 10 26 n/m 2 (E > 0.1 MeV) dose levels.« less

Biodosimetry Based on γ-H2AX Quantification and Cytogenetics after Partial- and Total-Body Irradiation during Fractionated Radiotherapy.

PubMed

Zahnreich, Sebastian; Ebersberger, Anne; Kaina, Bernd; Schmidberger, Heinz

2015-04-01

The aim of this current study was to quantitatively describe radiation-induced DNA damage and its distribution in leukocytes of cancer patients after fractionated partial- or total-body radiotherapy. Specifically, the impact of exposed anatomic region and administered dose was investigated in breast and prostate cancer patients receiving partial-body radiotherapy. DNA double-strand breaks (DSBs) were quantified by γ-H2AX immunostaining. The frequency of unstable chromosomal aberrations in stimulated lymphocytes was also determined and compared with the frequency of DNA DSBs in the same samples. The frequency of radiation-induced DNA damage was converted into dose, using ex vivo generated calibration curves, and was then compared with the administered physical dose. This study showed that 0.5 h after partial-body radiotherapy the quantity of radiation-induced γ-H2AX foci increased linearly with the administered equivalent whole-body dose for both tumor entities. Foci frequencies dropped 1 day thereafter but proportionality to the equivalent whole-body dose was maintained. Conversely, the frequency of radiation-induced cytogenetic damage increased from 0.5 h to 1 day after the first partial-body exposure with a linear dependence on the administered equivalent whole-body dose, for prostate cancer patients only. Only γ-H2AX foci assessment immediately after partial-body radiotherapy was a reliable measure of the expected equivalent whole-body dose. Local tumor doses could be approximated with both assays after one day. After total-body radiotherapy satisfactory dose estimates were achieved with both assays up to 8 h after exposure. In conclusion, the quantification of radiation-induced γ-H2AX foci, but not cytogenetic damage in peripheral leukocytes was a sensitive and rapid biodosimeter after acute heterogeneous irradiation of partial body volumes that was able to primarily assess the absorbed equivalent whole-body dose.

Quantitative assessment of the cataractogenic potential of very low doses of neutrons

NASA Technical Reports Server (NTRS)

Worgul, B. V.; Medvedovsky, C.; Huang, Y.; Marino, S. A.; Randers-Pehrson, G.; Brenner, D. J.

1996-01-01

We report on the prevalence and relative biological effectiveness (RBE) for various stages of lens opacification in rats induced by very low doses (2 to 250 mGy) of medium-energy (440 keV) neutrons, compared to those for X rays. Neutron doses were delivered either in a single fraction or in four separate fractions and the irradiated animals were followed for over 100 weeks. At the highest observed dose (250 mGy) and at early observation times, there was evidence of an inverse dose-rate effect; i.e., a fractionated exposure was more potent than a single exposure. Neutron RBEs relative to X rays were estimated using a non-parametric technique. The results were only weakly dependent on time postirradiation. At 30 weeks, for example, 80% confidence intervals for the RBE of acutely delivered neutrons relative to X rays were 8-16 at 250 mGy, 10-20 at 50 mGy, 50-100 at 10 mGy and 250-500 at 2 mGy. The results are consistent with the estimated neutron RBEs in Japanese A-bomb survivors, though broad confidence bounds are present in the Japanese results. Our findings are also consistent with data reported earlier for cataractogenesis induced by heavy ions in rats, mice, and rabbits. We conclude from these results that, at very low doses (<10 mGy), the RBE for neutron-induced cataractogenesis is considerably larger than the RBE of 20 commonly used, and use of a significantly larger value for calculating equivalent dose would be prudent.

Dose limits to the lens of the eye: International Basic Safety Standards and related guidance.

PubMed

Boal, T J; Pinak, M

2015-06-01

The International Atomic Energy Agency (IAEA) safety requirements: 'General Safety Requirements Part 3--Radiation protection and safety of radiation sources: International Basic Safety Standards' (BSS) was approved by the IAEA Board of Governors at its meeting in September 2011, and was issued as General Safety Requirements Part 3 in July 2014. The equivalent dose limit for the lens of the eye for occupational exposure in planned exposure situations was reduced from 150 mSv year(-1) to 20 mSv year(-1), averaged over defined periods of 5 years, with no annual dose in a single year exceeding 50 mSv. This reduction in the dose limit for the lens of the eye followed the recommendation of the International Commission on Radiological Protection in its statement on tissue reactions of 21 April 2011. IAEA has developed guidance on the implications of the new dose limit for the lens of the eye. This paper summarises the process that led to the inclusion of the new dose limit for the lens of the eye in the BSS, and the implications of the new dose limit. © The International Society for Prosthetics and Orthotics Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Fast method for in-flight estimation of total dose from protons and electrons using RADE Minstrument on JUICE

NASA Astrophysics Data System (ADS)

Hajdas, Wojtek; Mrigakshi, Alankrita; Xiao, Hualin

2017-04-01

The primary concern of the ESA JUICE mission to Jupiter is the harsh particle radiation environment. Ionizing particles introduce radiation damage by total dose effects, displacement damages or single events effects. Therefore, both the total ionizing dose and the displacement damage equivalent fluence must be assessed to alert spacecraft and its payload as well as to quantify radiation levels for the entire mission lifetime. We present a concept and implementations steps for simplified method used to compute in flight a dose rate and total dose caused by protons. We also provide refinement of the method previously developed for electrons. The dose rates values are given for predefined active volumes located behind layers of materials with known thickness. Both methods are based on the electron and proton flux measurements provided by the Electron and Proton Detectors inside the Radiation Hard Electron Monitor (RADEM) located on-board of JUICE. The trade-off between method accuracy and programming limitations for in-flight computations are discussed. More comprehensive and precise dose rate computations based on detailed analysis of all stack detectors will be made during off-line data processing. It will utilize full spectral unfolding from all RADEM detector subsystems.

External dose-rate conversion factors of radionuclides for air submersion, ground surface contamination and water immersion based on the new ICRP dosimetric setting.

PubMed

Yoo, Song Jae; Jang, Han-Ki; Lee, Jai-Ki; Noh, Siwan; Cho, Gyuseong

2013-01-01

For the assessment of external doses due to contaminated environment, the dose-rate conversion factors (DCFs) prescribed in Federal Guidance Report 12 (FGR 12) and FGR 13 have been widely used. Recently, there were significant changes in dosimetric models and parameters, which include the use of the Reference Male and Female Phantoms and the revised tissue weighting factors, as well as the updated decay data of radionuclides. In this study, the DCFs for effective and equivalent doses were calculated for three exposure settings: skyshine, groundshine and water immersion. Doses to the Reference Phantoms were calculated by Monte Carlo simulations with the MCNPX 2.7.0 radiation transport code for 26 mono-energy photons between 0.01 and 10 MeV. The transport calculations were performed for the source volume within the cut-off distances practically contributing to the dose rates, which were determined by a simplified calculation model. For small tissues for which the reduction of variances are difficult, the equivalent dose ratios to a larger tissue (with lower statistical errors) nearby were employed to make the calculation efficient. Empirical response functions relating photon energies, and the organ equivalent doses or the effective doses were then derived by the use of cubic-spline fitting of the resulting doses for 26 energy points. The DCFs for all radionuclides considered important were evaluated by combining the photon emission data of the radionuclide and the empirical response functions. Finally, contributions of accompanied beta particles to the skin equivalent doses and the effective doses were calculated separately and added to the DCFs. For radionuclides considered in this study, the new DCFs for the three exposure settings were within ±10 % when compared with DCFs in FGR 13.

External dose-rate conversion factors of radionuclides for air submersion, ground surface contamination and water immersion based on the new ICRP dosimetric setting

PubMed Central

Yoo, Song Jae; Jang, Han-Ki; Lee, Jai-Ki; Noh, Siwan; Cho, Gyuseong

2013-01-01

For the assessment of external doses due to contaminated environment, the dose-rate conversion factors (DCFs) prescribed in Federal Guidance Report 12 (FGR 12) and FGR 13 have been widely used. Recently, there were significant changes in dosimetric models and parameters, which include the use of the Reference Male and Female Phantoms and the revised tissue weighting factors, as well as the updated decay data of radionuclides. In this study, the DCFs for effective and equivalent doses were calculated for three exposure settings: skyshine, groundshine and water immersion. Doses to the Reference Phantoms were calculated by Monte Carlo simulations with the MCNPX 2.7.0 radiation transport code for 26 mono-energy photons between 0.01 and 10 MeV. The transport calculations were performed for the source volume within the cut-off distances practically contributing to the dose rates, which were determined by a simplified calculation model. For small tissues for which the reduction of variances are difficult, the equivalent dose ratios to a larger tissue (with lower statistical errors) nearby were employed to make the calculation efficient. Empirical response functions relating photon energies, and the organ equivalent doses or the effective doses were then derived by the use of cubic-spline fitting of the resulting doses for 26 energy points. The DCFs for all radionuclides considered important were evaluated by combining the photon emission data of the radionuclide and the empirical response functions. Finally, contributions of accompanied beta particles to the skin equivalent doses and the effective doses were calculated separately and added to the DCFs. For radionuclides considered in this study, the new DCFs for the three exposure settings were within ±10 % when compared with DCFs in FGR 13. PMID:23542764

Induction of Micronuclei in Human Fibroblasts from the Los Alamos High Energy Neutron Beam

NASA Technical Reports Server (NTRS)

Cox, Bradley

2009-01-01

The space radiation field includes a broad spectrum of high energy neutrons. Interactions between these neutrons and a spacecraft, or other material, significantly contribute to the dose equivalent for astronauts. The 15 degree beam line in the Weapons Neutron Research beam at Los Alamos Nuclear Science Center generates a neutron spectrum relatively similar to that seen in space. Human foreskin fibroblast (AG1522) samples were irradiated behind 0 to 20 cm of water equivalent shielding. The cells were exposed to either a 0.05 or 0.2 Gy entrance dose. Following irradiation, micronuclei were counted to see how the water shield affects the beam and its damage to cell nuclei. Micronuclei induction was then compared with dose equivalent data provided from a tissue equivalent proportional counter.

THE TREATMENT OF CHILDRENS' HEMANGIOMA AND NEVUS FLAMMEUS WITH Sr$sup 90$ AND Y$sup 9$$sup 0$ (in German)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lossl, H.; Jakob, A.

The authors report the excellent results obtained in the radiotherapy of the hemangioma of the child and of the nevus flammeus by means of strontium-90 and yttrium-90. The method is preferred to others as it reduces the charge of rays on the growing skeleton of the child ami on the gonads. In case of smaller lesions the application of strontium-90 (total dose 3000 to 5000 rep) and surface irradiation by means of yttrium-90 foils (total dose 3000 to 4000 rep) produce good results. The single dose should be around 1OOO rep. The dosage has to be fixed according to themore » erythema which appears with medium intensity. To judge from the gathered experiences the results of this therapy are equivalent to those of radium treatment or Chaoul's close irradiation. (auth)« less

Out-of-Field Dose Equivalents Delivered by Passively Scattered Therapeutic Proton Beams for Clinically Relevant Field Configurations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wroe, Andrew; Centre for Medical Radiation Physics, University of Wollongong, Wollongong; Clasie, Ben

2009-01-01

Purpose: Microdosimetric measurements were performed at Massachusetts General Hospital, Boston, MA, to assess the dose equivalent external to passively delivered proton fields for various clinical treatment scenarios. Methods and Materials: Treatment fields evaluated included a prostate cancer field, cranial and spinal medulloblastoma fields, ocular melanoma field, and a field for an intracranial stereotactic treatment. Measurements were completed with patient-specific configurations of clinically relevant treatment settings using a silicon-on-insulator microdosimeter placed on the surface of and at various depths within a homogeneous Lucite phantom. The dose equivalent and average quality factor were assessed as a function of both lateral displacement frommore » the treatment field edge and distance downstream of the beam's distal edge. Results: Dose-equivalent value range was 8.3-0.3 mSv/Gy (2.5-60-cm lateral displacement) for a typical prostate cancer field, 10.8-0.58 mSv/Gy (2.5-40-cm lateral displacement) for the cranial medulloblastoma field, 2.5-0.58 mSv/Gy (5-20-cm lateral displacement) for the spinal medulloblastoma field, and 0.5-0.08 mSv/Gy (2.5-10-cm lateral displacement) for the ocular melanoma field. Measurements of external field dose equivalent for the stereotactic field case showed differences as high as 50% depending on the modality of beam collimation. Average quality factors derived from this work ranged from 2-7, with the value dependent on the position within the phantom in relation to the primary beam. Conclusions: This work provides a valuable and clinically relevant comparison of the external field dose equivalents for various passively scattered proton treatment fields.« less

Chromosome Aberrations in Astronauts

NASA Technical Reports Server (NTRS)

George, Kerry A.; Durante, M.; Cucinotta, Francis A.

2007-01-01

A review of currently available data on in vivo induced chromosome damage in the blood lymphocytes of astronauts proves that, after protracted exposure of a few months or more to space radiation, cytogenetic biodosimetry analyses of blood collected within a week or two of return from space provides a reliable estimate of equivalent radiation dose and risk. Recent studies indicate that biodosimetry estimates from single spaceflights lie within the range expected from physical dosimetry and biophysical models, but very large uncertainties are associated with single individual measurements and the total sample population remains low. Retrospective doses may be more difficult to estimate because of the fairly rapid time-dependent loss of "stable" aberrations in blood lymphocytes. Also, biodosimetry estimates from individuals who participate in multiple missions, or very long (interplanetary) missions, may be complicated by an adaptive response to space radiation and/or changes in lymphocyte survival and repopulation. A discussion of published data is presented and specific issues related to space radiation biodosimetry protocols are discussed.

X-ray irradiation-induced structural changes on Single Wall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Bardi, N.; Jurewicz, I.; King, A. K.; Alkhorayef, M. A.; Bradley, D.; Dalton, A. B.

2017-11-01

Dosimetry devices based on Carbon Nanotubes are a promising new technology. In particular using devices based on single wall Carbon Nanotubes may offer a tissue equivalent response with the possibility for device miniaturisation, high scale manufacturing and low cost. An important precursor to device fabrication requires a quantitative study of the effects of X-ray radiation on the physical and chemical properties of the individual nanotubes. In this study, we concentrate on the effects of relatively low doses, 20 cGy and 45 cGy , respectively. We use a range of characterization techniques including scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to quantify the effects of the radiation dose on inherent properties of the nanotubes. Specifically we find that the radiation exposure results in a reduction in the sp2 nature of the nanotube bond structure. Moreover, our analysis indicates that the exposure results in nanotubes that have an increased defect density which ultimately effects the electrical properties of the nanotubes.

MO-FG-CAMPUS-TeP1-04: Pseudo-In-Vivo Dose Verification of a New Mono-Isocentric Technique for the Treatment of Multiple Brain Metastases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pappas, E P; Makris, D; Lahanas, V

2016-06-15

Purpose: To validate dose calculation and delivery accuracy of a recently introduced mono-isocentric technique for the treatment of multiple brain metastases in a realistic clinical case. Methods: Anonymized CT scans of a patient were used to model a hollow phantom that duplicates anatomy of the skull. A 3D printer was used to construct the phantom of a radiologically bone-equivalent material. The hollow phantom was subsequently filled with a polymer gel 3D dosimeter which also acted as a water-equivalent material. Irradiation plan consisted of 5 targets and was identical to the one delivered to the specific patient except for the prescriptionmore » dose which was optimized to match the gel dose-response characteristics. Dose delivery was performed using a single setup isocenter dynamic conformal arcs technique. Gel dose read-out was carried out by a 1.5 T MRI scanner. All steps of the corresponding patient’s treatment protocol were strictly followed providing an end-to-end quality assurance test. Pseudo-in-vivo measured 3D dose distribution and calculated one were compared in terms of spatial agreement, dose profiles, 3D gamma indices (5%/2mm, 20% dose threshold), DVHs and DVH metrics. Results: MR-identified polymerized areas and calculated high dose regions were found to agree within 1.5 mm for all targets, taking into account all sources of spatial uncertainties involved (i.e., set-up errors, MR-related geometric distortions and registration inaccuracies). Good dosimetric agreement was observed in the vast majority of the examined profiles. 3D gamma index passing rate reached 91%. DVH and corresponding metrics comparison resulted in a satisfying agreement between measured and calculated datasets within targets and selected organs-at-risk. Conclusion: A novel, pseudo-in-vivo QA test was implemented to validate spatial and dosimetric accuracy in treatment of multiple metastases. End-to-end testing demonstrated that our gel dosimetry phantom is suited for such QA procedures, allowing for 3D analysis of both targeting placement and dose.« less

Portable neutron spectrometer and dosimeter

DOEpatents

Waechter, D.A.; Erkkila, B.H.; Vasilik, D.G.

The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

Portable neutron spectrometer and dosimeter

DOEpatents

Waechter, David A.; Erkkila, Bruce H.; Vasilik, Dennis G.

1985-01-01

The disclosure relates to a battery operated neutron spectrometer/dosimeter utilizing a microprocessor, a built-in tissue equivalent LET neutron detector, and a 128-channel pulse height analyzer with integral liquid crystal display. The apparatus calculates doses and dose rates from neutrons incident on the detector and displays a spectrum of rad or rem as a function of keV per micron of equivalent tissue and also calculates and displays accumulated dose in millirads and millirem as well as neutron dose rates in millirads per hour and millirem per hour.

Structural and functional characterization of an anti-West Nile virus monoclonal antibody and its single-chain variant produced in glycoengineered plants

PubMed Central

Lai, Huafang; He, Junyun; Hurtado, Jonathan; Stahnke, Jake; Fuchs, Anja; Mehlhop, Erin; Gorlatov, Sergey; Loos, Andreas; Diamond, Michael S.; Chen, Qiang

2014-01-01

Previously, our group engineered a plant-derived monoclonal antibody (MAb pE16) that efficiently treated West Nile virus (WNV) infection in mice. In this study, we developed a pE16 variant consisting of a single-chain variable fragment (scFv) fused to the heavy chain constant domains (CH) of human IgG (pE16scFv-CH). pE16 and pE16scFv-CH were expressed and assembled efficiently in Nicotiana benthamiana ΔXF plants, a glycosylation mutant lacking plant specific N-glycan residues. Glycan analysis revealed that ΔXF plant-derived pE16scFv-CH (ΔXFpE16scFv-CH) and pE16 (ΔXFpE16) both displayed a mammalian glycosylation profile. ΔXFpE16 and ΔXFpE16scFv-CH demonstrated equivalent antigen binding affinity and kinetics, and slightly enhanced neutralization of WNV in vitro compared to the parent mammalian cell-produced E16 (mE16). A single dose of ΔXFpE16 or ΔXFpE16scFv-CH protected mice against WNV-induced mortality even 4 days after infection at equivalent rates as mE16. This study provides a detailed tandem comparison of the expression, structure and function of a therapeutic MAb and its single-chain variant produced in glycoengineered plants. Moreover, it demonstrates the development of anti-WNV MAb therapeutic variants that are equivalent in efficacy to pE16, simpler to produce, and likely safer to use as therapeutics due to their mammalian N-glycosylation. This platform may lead to a more robust and cost effective production of antibody-based therapeutics against WNV infection and other infectious, inflammatory, or neoplastic diseases. PMID:24975464

The damage equivalence of electrons, protons, alphas and gamma rays in rad-hard MOS devices

NASA Technical Reports Server (NTRS)

Stassinopoulos, E. G.; Van Gunten, O.; Brucker, G. J.; Knudson, A. R.; Jordan, T. M.

1983-01-01

This paper reports on a study of damage equivalence in rad-hard MOS devices with 100,000 rads (SiO2) capability. Damage sensitivities for electrons of 1, 2, 3, 5, and 7 MeV, protons of 1, 3, 7, 22, and 40 MeV, 3.4-MeV alphas, and Co-60 gammas were measured and compared. Results indicated that qualitatively the same charge recombination effects occurred in hard oxide devices for doses of 100,000 rads (SiO2) as in soft oxide parts for doses of 1 to 4 krads (SiO2). Consequently, damage equivalency or non-equivalency depended on radiation type and energy. However, recovery effects, both during and after irradiation, controlled relative damage sensitivity and its dependency on total dose, dose rate, supply bias, gate bias, radiation type, and energy. Correction factors can be derived from these data or from similar tests of other hard oxide type, so as to properly evaluate the combined effects of the total space environment.

Protracted exposure to fallout: the Rongelap and Utirik experience.

PubMed

Lessard, E T; Miltenberger, R P; Cohn, S H; Musolino, S V; Conard, R A

1984-03-01

From June 1946 to August 1958, the U.S. Department of Defense and the U.S. Atomic Energy Commission (AEC) conducted nuclear weapons tests in the Northern Marshall Islands. On 1 March 1954, BRAVO, an above-ground test in the Castle series, produced high levels of radioactive material, some of which subsequently fell on Rongelap and Utirik Atolls due to an unexpected wind shift. On 3 March 1954, the inhabitants of these atolls were moved out of the affected area. They later returned to Utirik in June 1954 and to Rongelap in June 1957. Comprehensive environmental and personnel radiological monitoring programs were initiated in the mid 1950s by Brookhaven National Laboratory to ensure that body burdens of the exposed Marshallese subjects remained within AEC guidelines. Their body-burden histories and calculated activity ingestion rate patterns post-return are presented along with estimates of internal committed effective dose equivalents. External exposure data are also included. In addition, relationships between body burden or urine-activity concentration and declining continuous intake were developed. The implications of these studies are: (1) the dietary intake of 137Cs was a major component contributing to the committed effective dose equivalent for the years after the initial contamination of the atolls; (2) for persons whose diet included fish, 65Zn was a major component of committed effective dose equivalent during the first years post-return; (3) a decline in the daily activity ingestion rate greater than that resulting from radioactive decay of the source was estimated for 137Cs, 65Zn, 90Sr and 60Co; (4) the relative impact of each nuclide on the estimate of committed effective dose equivalent was dependent upon the time interval between initial contamination and rehabilitation; and (5) the internal committed effective dose equivalent exceeded the external dose equivalent by a factor of 1.1 at Utirik and 1.5 at Rongelap during the rehabitation period. Few reliable 239Pu measurements on human excreta were made. An analysis of the tentative data leads to the conclusion that a reliable estimate of committed effective dose equivalent requires further research.

A conjugate of an anti-midkine single-chain variable fragment to doxorubicin inhibits tumor growth

PubMed Central

Zhao, Shuli; Zhao, Guangfeng; Xie, Hao; Huang, Yahong; Hou, Yayi

2012-01-01

Doxorubicin (DOX) was conjugated to a single-chain variable fragment (scFv) against human midkine (MK), and the conjugate (scFv-DOX) was used to target the chemotherapeutic agent to a mouse solid tumor model in which the tumor cells expressed high levels of human MK. The His-tagged recombinant scFv was expressed in bacteria, purified by metal affinity chromatography, and then conjugated to DOX using oxidative dextran (Dex) as a linker. The molecular formula of this immunoconjugate was scFv(Dex)1.3(DOX)20. In vitro apoptosis assays showed that the scFv-DOX conjugate was more cytotoxic against MK-transfected human adenocarcinoma cells (BGC823-MK) than untransfected cells (55.3 ± 2.4 vs 22.4 ± 3.8%) for three independent experiments. Nude mice bearing BGC823-MK solid tumors received scFv-DOX or equivalent doses of scFv + DOX for 2 weeks and tumor growth was more effectively inhibited by the scFv-DOX conjugate than by scFv + DOX (51.83% inhibition vs 40.81%). Histological analysis of the tumor tissues revealed that the highest levels of DOX accumulated in tumors from mice treated with scFv-DOX and this resulted in more extensive tumor cell death than in animals treated with the equivalent dose of scFv + DOX. These results show that the scFv-DOX conjugate effectively inhibited tumor growth in vivo and suggest that antigen-specific scFv may be competent drug-carriers. PMID:22267001

Fixed-dose combination ezetimibe+atorvastatin lowers LDL-C equivalent to co-administered components in randomized trials: use of a dose-response model.

PubMed

Bays, Harold E; Chen, Erluo; Tomassini, Joanne E; McPeters, Gail; Polis, Adam B; Triscari, Joseph

2015-04-01

Co-administration of ezetimibe with atorvastatin is a generally well-tolerated treatment option that reduces LDL-C levels and improves other lipids with greater efficacy than doubling the atorvastatin dose. The objective of the study was to demonstrate the equivalent lipid-modifying efficacy of fixed-dose combination (FDC) ezetimibe/atorvastatin compared with the component agents co-administered individually in support of regulatory filing. Two randomized, 6-week, double-blind cross-over trials compared the lipid-modifying efficacy of ezetimibe/atorvastatin 10/20 mg (n = 353) or 10/40 mg (n = 280) vs. separate co-administration of ezetimibe 10 mg plus atorvastatin 20 mg (n = 346) or 40 mg (n = 280), respectively, in hypercholesterolemic patients. Percent changes from baseline in LDL-C (primary endpoint) and other lipids (secondary endpoints) were assessed by analysis of covariance; triglycerides were evaluated by longitudinal-data analysis. Expected differences between FDC and the corresponding co-administered doses were predicted from a dose-response relationship model; sample size was estimated given the expected difference and equivalence margins (±4%). LDL-C-lowering equivalence was based on 97.5% expanded confidence intervals (CI) for the difference contained within the margins; equivalence margins for other lipids were not prespecified. Ezetimibe/atorvastatin FDC 10/20 mg was equivalent to co-administered ezetimibe+atorvastatin 20 mg in reducing LDL-C levels (54.0% vs. 53.8%) as was FDC 10/40 mg and ezetimibe+atorvastatin 40 mg (58.9% vs. 58.7%), as predicted by the model. Changes in other lipids were consistent with equivalence (97.5% expanded CIs <±3%, included 0); triglyceride changes varied more. All treatments were generally well tolerated. Hypercholesterolemic patients administered ezetimibe/atorvastatin 10/20 and 10/40 mg FDC had equivalent LDL-C lowering. This FDC formulation proved to be an efficacious and generally well-tolerated lipid-lowering therapy. © 2014 Société Française de Pharmacologie et de Thérapeutique.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moteabbed, M; Trofimov, A; Sharp, G

Purpose: To investigate the impact of anatomy/setup variations on standard vs. hypofractionated anterolateral pencil beam scanning (PBS) proton therapy for prostate cancer. Methods: Six prostate cancer patients treated with double-scattering proton therapy, who underwent weekly verification CT scans were selected. Implanted fiducials were used for localization, and endorectal balloons for immobilization. New PBS plans using combination of lateral and anterior-oblique (AO) (±35 deg) beams were created. AO beams were added to spare the femoral heads during hypofractionation. Lateral beams delivered 50.4 Gy(RBE) to prostate plus 5-15mm of seminal vesicles and AO beams 28.8 Gy(RBE) to prostate, in 44 fractions. PTVmore » was laterally expanded by 2.5% to account for range uncertainty. No range margins were applied for AO beams, assuming delivery with in-vivo range verification. Field-specific apertures with 1.2cm margin were used. Spot size was ∼9.5mm sigma for 172MeV @isocenter in air. Plans were optimized as single-field-uniform-dose with ∼5% maximum non-uniformity. The planned dose was recomputed on each weekly CT after aligning the fiducials with the simulation CT, scaled and accumulated via deformable image registration. Hypofractionated treatments with 12 and 5 fractions were considered. Equivalent doses were calculated for prostate (α/β= 1.5Gy), bladder and rectum (α/β= 3Gy). Results: The biological equivalent prostate dose was 86.2 and 92.9 Gyeq for the hypofractionation scenarios at 4.32 and 7.35 Gy/fx, respectively. The equivalent prostate D98 was degraded by on average 2.7 Gyeq for standard, and 3.1 and 4.0 Gyeq for the hypofractionated plans after accumulation. Differences between accumulated and planned Dmean/D2/EUD were generally reduced when reducing the number of fractions for bladder and rectum. The average Dmean/D2/EUD differences over all patients and organs-at-risk were 0.74/4.0/9.23, 0.49/3.64/5.51, 0.37/3.21/3.49 Gyeq for 44, 12 and 5 fractions. Conclusion: Hypofractionation makes proton therapy of prostate more susceptible to interfractional motion-induced target dose degradation compared to the standard fractionation.« less

Measurement of LET distribution and dose equivalent on board the space shuttle STS-65

NASA Technical Reports Server (NTRS)

Hayashi, T.; Doke, T.; Kikuchi, J.; Takeuchi, R.; Hasebe, N.; Ogura, K.; Nagaoka, S.; Kato, M.; Badhwar, G. D.

1996-01-01

Space radiation dosimetry measurements have been made on board the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called "Real-time Radiation Monitoring Device (RRMD)" utilizing silicon semi-conductor detectors and others are conventional detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. Using the RRMD detector, the first attempt of real-time monitoring of space radiation has been achieved successfully for a continuous period of 251.3 h, giving the temporal variations of LET distribution, particle count rates, and rates of absorbed dose and dose equivalent. The RRMD results indicate that a clear enhancement of the number of trapped particles is seen at the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent, while some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions for galactic cosmic ray particles (GCRs). Therefore, the main contribution to dose equivalent is seen to be due to GCRs in this low altitude mission (300 km). Also, the dose equivalent rates obtained by TLDs and CR-39 ranged from 146.9 to 165.2 microSv/day and the average quality factors from 1.45 to 1.57 depending on the locations and directions of detectors inside the Space-lab at this highly protected orbit for space radiation with a small inclination (28.5 degrees) and a low altitude (300 km). The LET distributions obtained by two different detectors, RRMD and CR-39, are in good agreement in the region of 15-200 keV/mm and difference of these distributions in the regions of LET < 15 keV/mm and LET > 200 keV/mm can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks.

Measurement of LET distribution and dose equivalent on board the space shuttle STS-65.

PubMed

Hayashi, T; Doke, T; Kikuchi, J; Takeuchi, R; Hasebe, N; Ogura, K; Nagaoka, S; Kato, M; Badhwar, G D

1996-11-01

Space radiation dosimetry measurements have been made on board the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called "Real-time Radiation Monitoring Device (RRMD)" utilizing silicon semi-conductor detectors and others are conventional detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. Using the RRMD detector, the first attempt of real-time monitoring of space radiation has been achieved successfully for a continuous period of 251.3 h, giving the temporal variations of LET distribution, particle count rates, and rates of absorbed dose and dose equivalent. The RRMD results indicate that a clear enhancement of the number of trapped particles is seen at the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent, while some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions for galactic cosmic ray particles (GCRs). Therefore, the main contribution to dose equivalent is seen to be due to GCRs in this low altitude mission (300 km). Also, the dose equivalent rates obtained by TLDs and CR-39 ranged from 146.9 to 165.2 microSv/day and the average quality factors from 1.45 to 1.57 depending on the locations and directions of detectors inside the Space-lab at this highly protected orbit for space radiation with a small inclination (28.5 degrees) and a low altitude (300 km). The LET distributions obtained by two different detectors, RRMD and CR-39, are in good agreement in the region of 15-200 keV/mm and difference of these distributions in the regions of LET < 15 keV/mm and LET > 200 keV/mm can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks.

Volumetric‐modulated arc therapy for the treatment of a large planning target volume in thoracic esophageal cancer

PubMed Central

Moseley, Douglas; Kassam, Zahra; Kim, Sun Mo; Cho, Charles

2013-01-01

Recently, volumetric‐modulated arc therapy (VMAT) has demonstrated the ability to deliver radiation dose precisely and accurately with a shorter delivery time compared to conventional intensity‐modulated fixed‐field treatment (IMRT). We applied the hypothesis of VMAT technique for the treatment of thoracic esophageal carcinoma to determine superior or equivalent conformal dose coverage for a large thoracic esophageal planning target volume (PTV) with superior or equivalent sparing of organs‐at‐risk (OARs) doses, and reduce delivery time and monitor units (MUs), in comparison with conventional fixed‐field IMRT plans. We also analyzed and compared some other important metrics of treatment planning and treatment delivery for both IMRT and VMAT techniques. These metrics include: 1) the integral dose and the volume receiving intermediate dose levels between IMRT and VMATI plans; 2) the use of 4D CT to determine the internal motion margin; and 3) evaluating the dosimetry of every plan through patient‐specific QA. These factors may impact the overall treatment plan quality and outcomes from the individual planning technique used. In this study, we also examined the significance of using two arcs vs. a single‐arc VMAT technique for PTV coverage, OARs doses, monitor units and delivery time. Thirteen patients, stage T2‐T3 N0‐N1 (TNM AJCC 7th edn.), PTV volume median 395 cc (range 281–601 cc), median age 69 years (range 53 to 85), were treated from July 2010 to June 2011 with a four‐field (n=4) or five‐field (n=9) step‐and‐shoot IMRT technique using a 6 MV beam to a prescribed dose of 50 Gy in 20 to 25 F. These patients were retrospectively replanned using single arc (VMATI, 91 control points) and two arcs (VMATII, 182 control points). All treatment plans of the 13 study cases were evaluated using various dose‐volume metrics. These included PTV D99, PTV D95, PTV V9547.5Gy(95%), PTV mean dose, Dmax, PTV dose conformity (Van't Riet conformation number (CN)), mean lung dose, lung V20 and V5, liver V30, and Dmax to the spinal canal prv3mm. Also examined were the total plan monitor units (MUs) and the beam delivery time. Equivalent target coverage was observed with both VMAT single and two‐arc plans. The comparison of VMATI with fixed‐field IMRT demonstrated equivalent target coverage; statistically no significant difference were found in PTV D99 (p=0.47), PTV mean (p=0.12), PTV D95 and PTV V9547.5Gy (95%) (p=0.38). However, Dmax in VMATI plans was significantly lower compared to IMRT (p=0.02). The Van't Riet dose conformation number (CN) was also statistically in favor of VMATI plans (p=0.04). VMATI achieved lower lung V20 (p=0.05), whereas lung V5 (p=0.35) and mean lung dose (p=0.62) were not significantly different. The other OARs, including spinal canal, liver, heart, and kidneys showed no statistically significant differences between the two techniques. Treatment time delivery for VMATI plans was reduced by up to 55% (p=5.8E−10) and MUs reduced by up to 16% (p=0.001). Integral dose was not statistically different between the two planning techniques (p=0.99). There were no statistically significant differences found in dose distribution of the two VMAT techniques (VMATI vs. VMATII) Dose statistics for both VMAT techniques were: PTV D99 (p=0.76), PTV D95 (p=0.95), mean PTV dose (p=0.78), conformation number (CN) (p=0.26), and MUs (p=0.1). However, the treatment delivery time for VMATII increased significantly by two‐fold (p=3.0E−11) compared to VMATI. VMAT‐based treatment planning is safe and deliverable for patients with thoracic esophageal cancer with similar planning goals, when compared to standard IMRT. The key benefit for VMATI was the reduction in treatment delivery time and MUs, and improvement in dose conformality. In our study, we found no significant difference in VMATII over single‐arc VMATI for PTV coverage or OARs doses. However, we observed significant increase in delivery time for VMATII compared to VMATI. PACS number: 87.53.Kn, 87.55.‐x PMID:23652258

Microbubble gas volume: A unifying dose parameter in blood-brain barrier opening by focused ultrasound.

PubMed

Song, Kang-Ho; Fan, Alexander C; Hinkle, Joshua J; Newman, Joshua; Borden, Mark A; Harvey, Brandon K

2017-01-01

Focused ultrasound with microbubbles is being developed to transiently, locally and noninvasively open the blood-brain barrier (BBB) for improved pharmaceutical delivery. Prior work has demonstrated that, for a given concentration dose, microbubble size affects both the intravascular circulation persistence and extent of BBB opening. When matched to gas volume dose, however, the circulation half-life was found to be independent of microbubble size. In order to determine whether this holds true for BBB opening as well, we independently measured the effects of microbubble size (2 vs. 6 µm diameter) and concentration, covering a range of overlapping gas volume doses (1-40 µL/kg). We first demonstrated precise targeting and a linear dose-response of Evans Blue dye extravasation to the rat striatum for a set of constant microbubble and ultrasound parameters. We found that dye extravasation increased linearly with gas volume dose, with data points from both microbubble sizes collapsing to a single line. A linear trend was observed for both the initial sonication (R 2 =0.90) and a second sonication on the contralateral side (R 2 =0.68). Based on these results, we conclude that microbubble gas volume dose, not size, determines the extent of BBB opening by focused ultrasound (1 MHz, ~0.5 MPa at the focus). This result may simplify planning for focused ultrasound treatments by constraining the protocol to a single microbubble parameter - gas volume dose - which gives equivalent results for varying size distributions. Finally, using optimal parameters determined for Evan Blue, we demonstrated gene delivery and expression using a viral vector, dsAAV1-CMV-EGFP, one week after BBB disruption, which allowed us to qualitatively evaluate neuronal health.

Water equivalency evaluation of PRESAGE® dosimeters for dosimetry of Cs-137 and Ir-192 brachytherapy sources

NASA Astrophysics Data System (ADS)

Gorjiara, Tina; Hill, Robin; Kuncic, Zdenka; Baldock, Clive

2010-11-01

A major challenge in brachytherapy dosimetry is the measurement of steep dose gradients. This can be achieved with a high spatial resolution three dimensional (3D) dosimeter. PRESAGE® is a polyurethane based dosimeter which is suitable for 3D dosimetry. Since an ideal dosimeter is radiologically water equivalent, we have investigated the relative dose response of three different PRESAGE® formulations, two with a lower chloride and bromide content than original one, for Cs-137 and Ir-192 brachytherapy sources. Doses were calculated using the EGSnrc Monte Carlo package. Our results indicate that PRESAGE® dosimeters are suitable for relative dose measurement of Cs-137 and Ir-192 brachytherapy sources and the lower halogen content PRESAGE® dosimeters are more water equivalent than the original formulation.

Reliability of equivalent sphere model in blood-forming organ dose estimation

NASA Technical Reports Server (NTRS)

Shinn, Judy L.; Wilson, John W.; Nealy, John E.

1990-01-01

The radiation dose equivalents to blood-forming organs (BFO's) of the astronauts at the Martian surface due to major solar flare events are calculated using the detailed body geometry of Langley and Billings. The solar flare spectra of February 1956, November 1960, and August 1972 events are employed instead of the idealized Webber form. The detailed geometry results are compared with those based on the 5-cm sphere model which was used often in the past to approximate BFO dose or dose equivalent. Larger discrepancies are found for the later two events possibly due to the lower numbers of highly penetrating protons. It is concluded that the 5-cm sphere model is not suitable for quantitative use in connection with future NASA deep-space, long-duration mission shield design studies.

Neuroleptic bioequivalency: tablet versus concentrate.

PubMed

Fann, W E; Moreira, A F

1985-01-01

Two forms of the antipsychotic neuroleptic molindone were administered to newly admitted psychotic patients. A coated tablet was administered for ten days, followed by administration of liquid concentrate in equivalent doses for four days. Plasma was analyzed by gas chromatography with electron capture for the parent compound following each dosing phase. Our data suggest that oral doses of the tablet and concentrate forms of this neuroleptic are equivalent in clinical bioavailability.

10 CFR 835.402 - Individual monitoring.

Code of Federal Regulations, 2010 CFR

2010-01-01

... conditions, are likely to receive one or more of the following: (i) An effective dose of 0.1 rem (0.001 Sv) or more in a year; (ii) An equivalent dose to the skin or to any extremity of 5 rems (0.05 Sv) or more in a year; (iii) An equivalent dose to the lens of the eye of 1.5 rems (0.015 Sv) or more in a...

10 CFR 835.402 - Individual monitoring.

Code of Federal Regulations, 2013 CFR

2013-01-01

... conditions, are likely to receive one or more of the following: (i) An effective dose of 0.1 rem (0.001 Sv) or more in a year; (ii) An equivalent dose to the skin or to any extremity of 5 rems (0.05 Sv) or more in a year; (iii) An equivalent dose to the lens of the eye of 1.5 rems (0.015 Sv) or more in a...

10 CFR 835.402 - Individual monitoring.

Code of Federal Regulations, 2011 CFR

2011-01-01

... conditions, are likely to receive one or more of the following: (i) An effective dose of 0.1 rem (0.001 Sv) or more in a year; (ii) An equivalent dose to the skin or to any extremity of 5 rems (0.05 Sv) or more in a year; (iii) An equivalent dose to the lens of the eye of 1.5 rems (0.015 Sv) or more in a...

10 CFR 835.402 - Individual monitoring.

Code of Federal Regulations, 2012 CFR

2012-01-01

... conditions, are likely to receive one or more of the following: (i) An effective dose of 0.1 rem (0.001 Sv) or more in a year; (ii) An equivalent dose to the skin or to any extremity of 5 rems (0.05 Sv) or more in a year; (iii) An equivalent dose to the lens of the eye of 1.5 rems (0.015 Sv) or more in a...

10 CFR 835.402 - Individual monitoring.

Code of Federal Regulations, 2014 CFR

2014-01-01

... conditions, are likely to receive one or more of the following: (i) An effective dose of 0.1 rem (0.001 Sv) or more in a year; (ii) An equivalent dose to the skin or to any extremity of 5 rems (0.05 Sv) or more in a year; (iii) An equivalent dose to the lens of the eye of 1.5 rems (0.015 Sv) or more in a...

Organ dose measurement using Optically Stimulated Luminescence Detector (OSLD) during CT examination

NASA Astrophysics Data System (ADS)

Yusuf, Muhammad; Alothmany, Nazeeh; Abdulrahman Kinsara, Abdulraheem

2017-10-01

This study provides detailed information regarding the imaging doses to patient radiosensitive organs from a kilovoltage computed tomography (CT) scan procedure using OSLD. The study reports discrepancies between the measured dose and the calculated dose from the ImPACT scan, as well as a comparison with the dose from a chest X-ray radiography procedure. OSLDs were inserted in several organs, including the brain, eyes, thyroid, lung, heart, spinal cord, breast, spleen, stomach, liver and ovaries, of the RANDO phantom. Standard clinical scanning protocols were used for each individual site, including the brain, thyroid, lung, breast, stomach, liver and ovaries. The measured absorbed doses were then compared with the simulated dose obtained from the ImPACT scan. Additionally, the equivalent doses for each organ were calculated and compared with the dose from a chest X-ray radiography procedure. Absorbed organ doses measured by OSLD in the RANDO phantom of up to 17 mGy depend on the organ scanned and the scanning protocols used. A maximum 9.82% difference was observed between the target organ dose measured by OSLD and the results from the ImPACT scan. The maximum equivalent organ dose measured during this experiment was equal to 99.899 times the equivalent dose from a chest X-ray radiography procedure. The discrepancies between the measured dose with the OSLD and the calculated dose from the ImPACT scan were within 10%. This report recommends the use of OSLD for measuring the absorbed organ dose during CT examination.

Dosimetric verification of small fields in the lung using lung-equivalent polymer gel and Monte Carlo simulation.

PubMed

Gharehaghaji, Nahideh; Dadgar, Habib Alah

2018-01-01

The main purpose of this study was evaluate a polymer-gel-dosimeter (PGD) for three-dimensional verification of dose distributions in the lung that is called lung-equivalent gel (LEG) and then to compare its result with Monte Carlo (MC) method. In the present study, to achieve a lung density for PGD, gel is beaten until foam is obtained, and then sodium dodecyl sulfate is added as a surfactant to increase the surface tension of the gel. The foam gel was irradiated with 1 cm × 1 cm field size in the 6 MV photon beams of ONCOR SIEMENS LINAC, along the central axis of the gel. The LEG was then scanned on a 1.5 Tesla magnetic resonance imaging scanner after irradiation using a multiple-spin echo sequence. Least-square fitting the pixel values from 32 consecutive images using a single exponential decay function derived the R2 relaxation rates. Moreover, 6 and 18 MV photon beams of ONCOR SIEMENS LINAC are simulated using MCNPX MC Code. The MC model is used to calculate the depth dose water and low-density water resembling the soft tissue and lung, respectively. Percentages of dose reduction in the lung region relative to homogeneous phantom for 6 MV photon beam were 44.6%, 39%, 13%, and 7% for 0.5 cm × 0.5 cm, 1 cm × 1 cm, 2 cm × 2 cm, and 3 cm × 3 cm fields, respectively. For 18 MV photon beam, the results were found to be 82%, 69%, 46%, and 25.8% for the same field sizes, respectively. Preliminary results show good agreement between depth dose measured with the LEG and the depth dose calculated using MCNP code. Our study showed that the dose reduction with small fields in the lung was very high. Thus, inaccurate prediction of absorbed dose inside the lung and also lung/soft-tissue interfaces with small photon beams may lead to critical consequences for treatment outcome.

Monitoring the eye lens: which dose quantity is adequate?

NASA Astrophysics Data System (ADS)

Behrens, R.; Dietze, G.

2010-07-01

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. The question of which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens arises from this situation. While in many countries dosemeters calibrated in terms of the dose equivalent quantity Hp(0.07) have been seen as being adequate for monitoring the dose to the eye lens, this might be questionable in the case of reduced dose limits and, thus, it may become necessary to use the dose equivalent quantity Hp(3) for this purpose. To discuss this question, the dose conversion coefficients for the equivalent dose of the eye lens (in the following eye lens dose) were determined for realistic photon and beta radiation fields and compared with the values of the corresponding conversion coefficients for the different operational quantities. The values obtained lead to the following conclusions: in radiation fields where most of the dose comes from photons, especially x-rays, it is appropriate to use dosemeters calibrated in terms of Hp(0.07) on a slab phantom, while in other radiation fields (dominated by beta radiation or unknown contributions of photon and beta radiation) dosemeters calibrated in terms of Hp(3) on a slab phantom should be used. As an alternative, dosemeters calibrated in terms of Hp(0.07) on a slab phantom could also be used; however, in radiation fields containing beta radiation with the end point energy near 1 MeV, an overestimation of the eye lens dose by up to a factor of 550 is possible.

Monitoring the eye lens: which dose quantity is adequate?

PubMed

Behrens, R; Dietze, G

2010-07-21

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. The question of which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens arises from this situation. While in many countries dosemeters calibrated in terms of the dose equivalent quantity H(p)(0.07) have been seen as being adequate for monitoring the dose to the eye lens, this might be questionable in the case of reduced dose limits and, thus, it may become necessary to use the dose equivalent quantity H(p)(3) for this purpose. To discuss this question, the dose conversion coefficients for the equivalent dose of the eye lens (in the following eye lens dose) were determined for realistic photon and beta radiation fields and compared with the values of the corresponding conversion coefficients for the different operational quantities. The values obtained lead to the following conclusions: in radiation fields where most of the dose comes from photons, especially x-rays, it is appropriate to use dosemeters calibrated in terms of H(p)(0.07) on a slab phantom, while in other radiation fields (dominated by beta radiation or unknown contributions of photon and beta radiation) dosemeters calibrated in terms of H(p)(3) on a slab phantom should be used. As an alternative, dosemeters calibrated in terms of H(p)(0.07) on a slab phantom could also be used; however, in radiation fields containing beta radiation with the end point energy near 1 MeV, an overestimation of the eye lens dose by up to a factor of 550 is possible.

Radiation dosimetry measurements during U.S. Space Shuttle missions with the RME-III.

PubMed

Golightly, M J; Hardy, K; Quam, W

1994-01-01

Time-resolved radiation dosimetry measurements inside the crew compartment have been made during recent Shuttle missions with the U.S. Air Force Radiation Monitoring Equipment-III (RME-III), a portable battery-powered four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. Half of the missions had orbital inclinations of 28.5 degrees with the remainder at inclinations of 57 degrees or greater; altitudes ranged from 300 to 600 km. The determined dose equivalent rates ranged from 70 to 5300 microSv/day. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicles. Measurements indicate that medium- and high-LET particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isocontours of fluence, dose and dose equivalent rate have been developed from measurements made during the STS-28 mission. The drift rate of the South Atlantic Anomaly is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and GCR dose for the STS-28 mission was significantly lower than the measured values.

Development of an effective dose coefficient database using a computational human phantom and Monte Carlo simulations to evaluate exposure dose for the usage of NORM-added consumer products.

PubMed

Yoo, Do Hyeon; Shin, Wook-Geun; Lee, Jaekook; Yeom, Yeon Soo; Kim, Chan Hyeong; Chang, Byung-Uck; Min, Chul Hee

2017-11-01

After the Fukushima accident in Japan, the Korean Government implemented the "Act on Protective Action Guidelines Against Radiation in the Natural Environment" to regulate unnecessary radiation exposure to the public. However, despite the law which came into effect in July 2012, an appropriate method to evaluate the equivalent and effective doses from naturally occurring radioactive material (NORM) in consumer products is not available. The aim of the present study is to develop and validate an effective dose coefficient database enabling the simple and correct evaluation of the effective dose due to the usage of NORM-added consumer products. To construct the database, we used a skin source method with a computational human phantom and Monte Carlo (MC) simulation. For the validation, the effective dose was compared between the database using interpolation method and the original MC method. Our result showed a similar equivalent dose across the 26 organs and a corresponding average dose between the database and the MC calculations of < 5% difference. The differences in the effective doses were even less, and the result generally show that equivalent and effective doses can be quickly calculated with the database with sufficient accuracy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of levothyroxine sodium bioavailability: recommendations for an improved methodology based on the pooled analysis of eight identically designed trials with 396 drug exposures.

PubMed

Walter-Sack, Ingeborg; Clanget, Christof; Ding, Reinhard; Goeggelmann, Christoph; Hinke, Vera; Lang, Matthias; Pfeilschifter, Johannes; Tayrouz, Yorki; Wegscheider, Karl

2004-01-01

Assessment of dosage form performance in delivering endogenous compounds, such as hormones, in vivo requires a specific approach. Assessment of relative bioavailability of levothyroxine sodium (L-T4) from eight solid preparations, compared with a liquid formulation, by using pharmacological doses, and critical evaluation of trial methodology based on the pooled analysis of individual data. Eight open-label, randomised, single-dose, crossover phase I studies using eight solid L-T4 dosage forms (25, 50, 75, 100, 125, 150, 175, 200 microg per tablet; administered total doses 600, 625 or 700 microg) and a liquid formulation; assessment of relative bioavailability by 90% confidence intervals for the relative area under the concentration-time curve (AUC) of total thyroxine (TT4), i.e. protein-bound plus free thyroxine, calculated by using the recommended log AUC four-way analysis of variance models for crossover designs. For the pooled analysis, general linear models were applied to assess the validity of model assumptions, to identify potential sources of effect modification, to discuss alternative modelling approaches with respect to endogenous hormone secretion and to give recommendations for future designs and sample sizes. One hundred and sixty-nine healthy males; 29 of these individuals participating in two studies. Single oral doses of L-T4 tablets and the liquid formulation administered after fasting, separated by at least 6 weeks; a total of 396 drug exposures. TT4 AUC from 0 to 48 hours and peak plasma concentration with and without baseline correction. Each study demonstrated equivalence of the tablets to the drinking solution, independent of the chosen analysis model. Sequence effects that could devalidate the chosen crossover approach were not found. Period effects with changing directions that could best be explained by seasonal variation were detected. While the pre-specified method of baseline correction of simply subtracting individual time-zero TT4 values was disadvantageous, the analysis of total AUC could be improved considerably by covariate adjustment for baseline TT4. With this approach, sample sizes could have been substantially reduced or, alternatively, the recommended equivalence ranges could be reduced to +/-6%. Using a single pharmacological dose of L-T4 in two-period crossover designs is a safe and reliable procedure to assess L-T4 dosage form performance. With an adequate statistical modelling approach, the design is efficient and allows general conclusions with moderate sample sizes.

Variable dose rate single-arc IMAT delivered with a constant dose rate and variable angular spacing

NASA Astrophysics Data System (ADS)

Tang, Grace; Earl, Matthew A.; Yu, Cedric X.

2009-11-01

Single-arc intensity-modulated arc therapy (IMAT) has gained worldwide interest in both research and clinical implementation due to its superior plan quality and delivery efficiency. Single-arc IMAT techniques such as the Varian RapidArc™ deliver conformal dose distributions to the target in one single gantry rotation, resulting in a delivery time in the order of 2 min. The segments in these techniques are evenly distributed within an arc and are allowed to have different monitor unit (MU) weightings. Therefore, a variable dose-rate (VDR) is required for delivery. Because the VDR requirement complicates the control hardware and software of the linear accelerators (linacs) and prevents most existing linacs from delivering IMAT, we propose an alternative planning approach for IMAT using constant dose-rate (CDR) delivery with variable angular spacing. We prove the equivalence by converting VDR-optimized RapidArc plans to CDR plans, where the evenly spaced beams in the VDR plan are redistributed to uneven spacing such that the segments with larger MU weighting occupy a greater angular interval. To minimize perturbation in the optimized dose distribution, the angular deviation of the segments was restricted to <=± 5°. This restriction requires the treatment arc to be broken into multiple sectors such that the local MU fluctuation within each sector is reduced, thereby lowering the angular deviation of the segments during redistribution. The converted CDR plans were delivered with a single gantry sweep as in the VDR plans but each sector was delivered with a different value of CDR. For four patient cases, including two head-and-neck, one brain and one prostate, all CDR plans developed with the variable spacing scheme produced similar dose distributions to the original VDR plans. For plans with complex angular MU distributions, the number of sectors increased up to four in the CDR plans in order to maintain the original plan quality. Since each sector was delivered with a different dose rate, extra mode-up time (xMOT) was needed between the transitions of the successive sectors during delivery. On average, the delivery times of the CDR plans were approximately less than 1 min longer than the treatment times of the VDR plans, with an average of about 0.33 min of xMOT per sector transition. The results have shown that VDR may not be necessary for single-arc IMAT. Using variable angular spacing, VDR RapidArc plans can be implemented into the clinics that are not equipped with the new VDR-enabled machines without compromising the plan quality or treatment efficiency. With a prospective optimization approach using variable angular spacing, CDR delivery times can be further minimized while maintaining the high delivery efficiency of single-arc IMAT treatment.

A single serving of caffeinated coffee impairs postprandial glucose metabolism in overweight men.

PubMed

Robertson, Tracey M; Clifford, Michael N; Penson, Simon; Chope, Gemma; Robertson, M Denise

2015-10-28

Previous studies regarding the acute effects of coffee on glycaemic control have used a single large dose of coffee, typically containing the caffeine equivalent of 2-4 servings of coffee. This study investigates whether the acute effects of coffee are dose-dependent, starting with a single serving. A total of ten healthy overweight males participated in a two-part randomised double-blind cross-over study. In the first part, they ingested 2, 4 or 8 g instant decaffeinated coffee (DC) dissolved in 400 ml water with caffeine added in proportion to the DC (total 100, 200 or 400 mg caffeine) or control (400 ml water) all with 50 g glucose. In the second part, they ingested the same amounts of DC (2, 4, 8 g) or control, but with a standard 100 mg caffeine added to each. Capillary blood samples were taken every 15 min for 2 h after each drink and glucose and insulin levels were measured. Repeated measures ANOVA on glucose results found an effect when caffeine was varied in line with DC (P=0·008). Post hoc analysis revealed that both 2 and 4 g DC with varied caffeine content increased the glycaemic response v. There was no effect of escalating doses of DC when caffeine remained constant at 100 mg. These results demonstrate that one standard serving of coffee (2 g) is sufficient to affect glucose metabolism. Furthermore, the amount of caffeine found in one serving (100 mg) is sufficient to mask any potential beneficial effects of increasing other components. No dose-dependent effect was found.

Brain injury and development in preterm infants exposed to fentanyl

PubMed Central

McPherson, Christopher; Haslam, Matthew; Pineda, Roberta; Rogers, Cynthia; Neil, Jeffrey J.; Inder, Terrie E.

2015-01-01

Background Fentanyl is commonly utilized in preterm infants. Relatively little is known regarding the neurodevelopmental outcomes of preterm infants exposed to fentanyl. Objective To investigate the association between cumulative fentanyl dose and brain injury and diameters in a cohort of preterm infants Methods Data on demographics, perinatal course, and neonatal course, including total fentanyl exposure prior to term equivalent age, were retrospectively evaluated for 103 infants born at ≤ 30 weeks gestational age who underwent magnetic resonance imaging at term equivalent age (mean gestational age 26.9 ± 1.8 weeks). Magnetic resonance images were evaluated for brain injury and regional brain diameters. Developmental testing was conducted at term equivalent and 2 years of age. Results Seventy-eight infants (76%) received fentanyl (median cumulative dose 3 μg/kg, interquartile range 1 – 441 μg/kg). Cumulative fentanyl dose in the first week of life correlated with the incidence of cerebellar hemorrhage after correction for covariates (OR 2.1, 95% confidence interval 1.1 – 4.1). Cumulative fentanyl dose before term equivalent age correlated with reductions in transverse cerebellar diameter after correction for covariates including the presence of cerebellar hemorrhage (r = 0.461, p = 0.002). No correlation was detected between cumulative fentanyl dose and development at 2 years of age. Conclusions Higher cumulative fentanyl dose in preterm infants correlated with a higher incidence of cerebellar injury and lower cerebellar diameter at term equivalent age. Our findings must be taken with caution, but emphasize the need for future prospective trials examining the risks and benefits of commonly utilized analgesic agents in preterm infants. PMID:26369570

Ethanol immunosuppression in vitro

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaplan, D.R.

Ethanol in concentrations equivalent to levels achieved by the ingestion of moderate to large amounts of alcoholic beverages has been shown to inhibit mitogen and anti-CD3 stimulated human T lymphocyte proliferation. This inhibition was monophasic suggesting that ethanol affected a single limiting component of T cell proliferation. In experiments designed to test the effect of ethanol on various aspects of proliferation, it was demonstrated that ethanol inhibited the capacity of exogenously supplied interleukin 2 to stimulate proliferation of T cells that had previously acquired interleukin 2 receptors in a monophasic, dose-dependent manner. Moreover, there was no suppression of interleukin 2more » production or interleukin 2 receptor acquisition. Thus, ethanol was shown to mediate immunosuppression by a mechanism specific to one component of proliferation. Additive inhibition of T cell proliferation was seen with ethanol plus cyclosporin A which inhibits interleukin 2 production. The level of inhibition with 250 ng/ml cyclosporin A alone was equivalent to the level seen with 62 ng/ml cyclosporin A plus 20 mM (94 mg%) ethanol. Ethanol also suppressed an immune effector mechanism. NK cytotoxicity was depressed in a monophasic, dose-dependent manner. Thus, ethanol might be considered as a possible adjunct in immunosuppressive therapy.« less

Bioequivalence Between Generic and Branded Lamotrigine in People With Epilepsy: The EQUIGEN Randomized Clinical Trial.

PubMed

Berg, Michel; Welty, Timothy E; Gidal, Barry E; Diaz, Francisco J; Krebill, Ron; Szaflarski, Jerzy P; Dworetzky, Barbara A; Pollard, John R; Elder, Edmund J; Jiang, Wenlei; Jiang, Xiaohui; Switzer, Regina D; Privitera, Michael D

2017-08-01

Switching between generic antiepileptic drugs is a highly debated issue that affects both clinical care and overall health care costs. To evaluate the single-dose pharmacokinetic bioequivalence of 3 (1 branded and 2 generic drugs) on-market, immediate-release lamotrigine drug products. The Equivalence Among Antiepileptic Drug Generic and Brand Products in People With Epilepsy (EQUIGEN) single-dose study is a crossover, prospective, sequence-randomized, replicate pharmacokinetic study conducted at 5 US academic epilepsy centers. Fifty adults (≥18 years) with epilepsy who were taking concomitant antiepileptic drugs and not currently receiving lamotrigine were enrolled between July 18, 2013, and January 19, 2015. Every participant was randomly assigned to 1 of 3 equivalent sequences, each comprising 6 study periods, during which they had blood draws before and after medication administration. Forty-nine participants were included in intention-to-treat analyses. Participants received a single 25-mg dose of immediate-release lamotrigine at the start of each period, with the branded and the 2 most disparate generic products each studied twice. Lamotrigine was selected as the antiepileptic drug of interest because of its wide use, publications indicating problems with generic switches, and complaints to the US Food and Drug Administration regarding generic products. Both participants and study personnel were blinded to the specific generic products selected. The primary outcome was bioequivalence between products. Maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC) were compared, and average bioequivalence (ABE) was established if the 90% CIs of the ratios of the 2 products were within equivalence limits (80%-125%). Of the 50 randomized participants, 49 (98%) received all 3 lamotrigine products and completed at least 3 pharmacokinetic assessments and 46 (92%) completed all 6 pharmacokinetic assessments. Among the 49 participants, 28 (57%) were men and 21 (43%) were women, 42 (86%) self-identified as white, and 46 (16) years was the mean (SD) age. The 3 drug products were considered bioequivalent because the 90% CIs were within equivalence limits (lowest and highest CI limits for Cmax, 92.6% and 110.4%; for AUC0-96, 96.9% and 101.9%). Replicate testing demonstrated no significant differences in within-subject variability across the 3 products (likelihood ratios, χ22 for log-transformed variables: AUC0-96, 2.58; Cmax, 0.64; and AUC0-∞, 4.05; P ≥ .13) and that the 3 products were also bioequivalent according to scaled ABE and individual bioequivalence criteria with no subject × formulation interaction (Cmax, 0.00; AUC0-96, 0.54; and AUC0-∞, 0.36; P ≥ .76). This study provides evidence that the disparate lamotrigine products studied are bioequivalent when tested in people with epilepsy taking concomitant antiepileptic drugs. clinicaltrials.gov Identifier: NCT01733394.

Quantifying the interplay effect in prostate IMRT delivery using a convolution-based method.

PubMed

Li, Haisen S; Chetty, Indrin J; Solberg, Timothy D

2008-05-01

The authors present a segment-based convolution method to account for the interplay effect between intrafraction organ motion and the multileaf collimator position for each particular segment in intensity modulated radiation therapy (IMRT) delivered in a step-and-shoot manner. In this method, the static dose distribution attributed to each segment is convolved with the probability density function (PDF) of motion during delivery of the segment, whereas in the conventional convolution method ("average-based convolution"), the static dose distribution is convolved with the PDF averaged over an entire fraction, an entire treatment course, or even an entire patient population. In the case of IMRT delivered in a step-and-shoot manner, the average-based convolution method assumes that in each segment the target volume experiences the same motion pattern (PDF) as that of population. In the segment-based convolution method, the dose during each segment is calculated by convolving the static dose with the motion PDF specific to that segment, allowing both intrafraction motion and the interplay effect to be accounted for in the dose calculation. Intrafraction prostate motion data from a population of 35 patients tracked using the Calypso system (Calypso Medical Technologies, Inc., Seattle, WA) was used to generate motion PDFs. These were then convolved with dose distributions from clinical prostate IMRT plans. For a single segment with a small number of monitor units, the interplay effect introduced errors of up to 25.9% in the mean CTV dose compared against the planned dose evaluated by using the PDF of the entire fraction. In contrast, the interplay effect reduced the minimum CTV dose by 4.4%, and the CTV generalized equivalent uniform dose by 1.3%, in single fraction plans. For entire treatment courses delivered in either a hypofractionated (five fractions) or conventional (> 30 fractions) regimen, the discrepancy in total dose due to interplay effect was negligible.

Model Comparisons For Space Solar Cell End-Of-Life Calculations

NASA Astrophysics Data System (ADS)

Messenger, Scott; Jackson, Eric; Warner, Jeffrey; Walters, Robert; Evans, Hugh; Heynderickx, Daniel

2011-10-01

Space solar cell end-of-life (EOL) calculations are performed over a wide range of space radiation environments for GaAs-based single and multijunction solar cell technologies. Two general semi-empirical approaches will used to generate these EOL calculation results: 1) the JPL equivalent fluence (EQFLUX) and 2) the NRL displacement damage dose (SCREAM). This paper also includes the first results using the Monte Carlo-based version of SCREAM, called MC- SCREAM, which is now freely available online as part of the SPENVIS suite of programs.

Annual environmental monitoring report of the Lawrence Berkeley Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schleimer, G.E.

1983-04-01

In order to establish whether LBL research activities produces any impact on the population surrounding the Laboratory, a program of environmental air and water sampling and continuous radiation monitoring was carried on throughout the year. For 1982, as in the previous several years, doses attributable to LBL radiological operations were a small fraction of the relevant radiation protection guidelines (RPG). The maximum perimeter dose equivalent was less than or equal to 24.0 mrem (the 1982 dose equivalent measured at the Building 88 monitoring station B-13A, about 5% of the RPG). The total population dose equivalent attributable to LBL operations duringmore » 1982 was less than or equal to 16 man-rem, about 0.002% of the RPG of 170 mrem/person to a suitable sample of the population.« less

The use of displacement damage dose to correlate degradation in solar cells exposed to different radiations

NASA Technical Reports Server (NTRS)

Summers, Geoffrey P.; Burke, Edward A.; Shapiro, Philip; Statler, Richard; Messenger, Scott R.; Walters, Robert J.

1994-01-01

It has been found useful in the past to use the concept of 'equivalent fluence' to compare the radiation response of different solar cell technologies. Results are usually given in terms of an equivalent 1 MeV electron or an equivalent 10 MeV proton fluence. To specify cell response in a complex space-radiation environment in terms of an equivalent fluence, it is necessary to measure damage coefficients for a number of representative electron and proton energies. However, at the last Photovoltaic Specialist Conference we showed that nonionizing energy loss (NIEL) could be used to correlate damage coefficients for protons, using measurements for GaAs as an example. This correlation means that damage coefficients for all proton energies except near threshold can be predicted from a measurement made at one particular energy. NIEL is the exact equivalent for displacement damage of linear energy transfer (LET) for ionization energy loss. The use of NIEL in this way leads naturally to the concept of 10 MeV equivalent proton fluence. The situation for electron damage is more complex, however. It is shown that the concept of 'displacement damage dose' gives a more general way of unifying damage coefficients. It follows that 1 MeV electron equivalent fluence is a special case of a more general quantity for unifying electron damage coefficients which we call the 'effective 1 MeV electron equivalent dose'.

Treatment with liraglutide--a once-daily GLP-1 analog--does not reduce the bioavailability of ethinyl estradiol/levonorgestrel taken as an oral combination contraceptive drug.

PubMed

Jacobsen, Lisbeth V; Vouis, Jan; Hindsberger, Charlotte; Zdravkovic, Milan

2011-12-01

Liraglutide is a once-daily human GLP-1 analog for treatment of type 2 diabetes. Like other GLP-1 analogs, liraglutide delays gastric emptying, which could potentially affect absorption of concomitantly administered oral drugs. This study investigated the effect of liraglutide on the pharmacokinetics of the components of an oral contraceptive (ethinyl estradiol/levonorgestrel). Postmeno-pausal healthy women (n = 21) were included. A single dose of this contraceptive was administered. Blood samples for ethinyl estradiol/levonorgestrel measurements were drawn until 74 hours post dosing of the contraceptive during liraglutide and placebo treatments. The 90% confidence interval (CI) of the ratio of the area under the curve (AUC) (1.06; 90% CI, 0.99-1.13) for ethinyl estradiol (during liraglutide and placebo) was within defined limits, demonstrating equivalence. The 90% CI for the ratio of AUC for levonorgestrel was not fully contained within the limits (1.18; 90% CI, 1.04-1.34) (levonorgestrel AUC was 18% greater with liraglutide vs placebo). However, equivalence was demonstrated for levonorgestrel AUC(0-t) (1.15; 90% CI, 1.06-1.24). Equivalence was not demonstrated for maximum concentration (C(max)); values for ethinyl estradiol and levonorgestrel C(max) were 12% and 13% lower with liraglutide versus placebo, respectively. Both reached C(max) ~1.5 hours later with liraglutide. No clinically relevant reduction in bioavailability of ethinyl estradiol/levonorgestrel occurred.

Non-vascular interventional procedures: effective dose to patient and equivalent dose to abdominal organs by means of DICOM images and Monte Carlo simulation.

PubMed

Longo, Mariaconcetta; Marchioni, Chiara; Insero, Teresa; Donnarumma, Raffaella; D'Adamo, Alessandro; Lucatelli, Pierleone; Fanelli, Fabrizio; Salvatori, Filippo Maria; Cannavale, Alessandro; Di Castro, Elisabetta

2016-03-01

This study evaluates X-ray exposure in patient undergoing abdominal extra-vascular interventional procedures by means of Digital Imaging and COmmunications in Medicine (DICOM) image headers and Monte Carlo simulation. The main aim was to assess the effective and equivalent doses, under the hypothesis of their correlation with the dose area product (DAP) measured during each examination. This allows to collect dosimetric information about each patient and to evaluate associated risks without resorting to in vivo dosimetry. The dose calculation was performed in 79 procedures through the Monte Carlo simulator PCXMC (A PC-based Monte Carlo program for calculating patient doses in medical X-ray examinations), by using the real geometrical and dosimetric irradiation conditions, automatically extracted from DICOM headers. The DAP measurements were also validated by using thermoluminescent dosemeters on an anthropomorphic phantom. The expected linear correlation between effective doses and DAP was confirmed with an R(2) of 0.974. Moreover, in order to easily calculate patient doses, conversion coefficients that relate equivalent doses to measurable quantities, such as DAP, were obtained. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

LDL-C goal attainment in patients who remain on atorvastatin or switch to equivalent or non-equivalent doses of simvastatin: a retrospective matched cohort study in clinical practice.

PubMed

Rublee, Dale A; Burke, James P

2010-03-01

As clinical trials have shown the benefits of more intensive cholesterol control, treatment targets for low-density lipoprotein cholesterol (LDL-C) have decreased progressively. At the same time, physicians have been encouraged to contain costs by prescribing cheaper, generic statins for cholesterol management. To determine how these possibly conflicting goals are managed in clinical practice, we examined LDL-C control in patients switched from a potent, branded statin (atorvastatin) to a less potent, generic statin (simvastatin). Patients who switched from atorvastatin to simvastatin between July 2006 and January 2008 were retrospectively identified from a US medical and pharmacy claims database, and matched with controls remaining on atorvastatin. Outcomes measured were the number of switched patients receiving a simvastatin milligram dose>or=2 times their previous atorvastatin dose, changes in LDL-C levels, and percentage of patients achieving recommended LDL-C targets. All study variables were analyzed descriptively. After applying exclusion and inclusion criteria, 1048 patients who switched from atorvastatin to simvastatin and 1048 matched controls who remained on atorvastatin were included. Among the switchers, 379 (36%) received an inappropriately low dose of simvastatin (<2 times atorvastatin dose). In patients remaining on atorvastatin, mean LDL-C decreased from 105.7 mg/dL to 102.3 mg/dL after 44 weeks, whereas in switched patients, LDL-C remained similar, at 105.9 mg/dL on atorvastatin and 105.8 mg/dL on simvastatin. Before switching, when all patients were receiving atorvastatin, 67.4% of switchers and 69.9% of controls achieved recommended LDL-C targets. After switching, significantly fewer switchers than controls met LDL-C targets (69.1% vs 74.6%; P=0.005). However, among patients who switched to an equivalent dose of simvastatin (>or=2 times prior atorvastatin dose), similar proportions met LDL-C targets (72.8% vs 74.6% of controls; P=0.402), whereas among patients who switched to inappropriate non-equivalent dose of simvastatin, a significantly lower proportion met LDL-C targets (62.5% vs 74.6% of controls; P=0.001). Continuing atorvastatin was associated with lower LDL-C levels and better LDL-C target attainment compared with switching to simvastatin. Patients switched to an equivalent simvastatin dose had lower LDL-C levels and were more likely to achieve LDL-C targets than patients switched to a non-equivalent dose, suggesting physicians must consider dosage equivalence when switching statins, and should measure LDL-C and titrate statins as necessary to achieve LDL-C control.

10 CFR 835.203 - Combining internal and external equivalent doses.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Combining internal and external equivalent doses. 835.203 Section 835.203 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and... the radiation and tissue weighting factor values provided in § 835.2. [72 FR 31926, June 8, 2007] ...

10 CFR 835.203 - Combining internal and external equivalent doses.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Combining internal and external equivalent doses. 835.203 Section 835.203 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and... the radiation and tissue weighting factor values provided in § 835.2. [72 FR 31926, June 8, 2007] ...

10 CFR 835.203 - Combining internal and external equivalent doses.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Combining internal and external equivalent doses. 835.203 Section 835.203 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and... the radiation and tissue weighting factor values provided in § 835.2. [72 FR 31926, June 8, 2007] ...

10 CFR 835.203 - Combining internal and external equivalent doses.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Combining internal and external equivalent doses. 835.203 Section 835.203 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal and... the radiation and tissue weighting factor values provided in § 835.2. [72 FR 31926, June 8, 2007] ...

Passive dosimetry aboard the Mir Orbital Station: external measurements.

PubMed

Benton, E R; Benton, E V; Frank, A L

2002-10-01

This paper reports results from the first measurements made on the exterior of a LEO spacecraft of mean dose equivalent rate and average quality factor as functions of shielding depth for shielding less than 1 g/cm2 Al equivalent. Two sets of measurements were made on the outside of the Mir Orbital Station; one near solar maximum in June 1991 and one near solar minimum in 1997. Absorbed dose was measured using stacks of TLDs. LET spectrum from charged particles of LET infinity H2O > o r= 5keV/micrometers was measured using stacks of CR-39 PNTDs. Results from the TLD and PNTD measurements at a given shielding depth were combined to yield mean total dose rate, mean dose equivalent rate, and average quality factor. Measurements made near solar maximum tend to be greater than those made during solar minimum. Both mean dose rate and mean dose equivalent rate decrease by nearly four orders of magnitude within the first g/cm2 shielding illustrating the attenuation of both trapped electrons and low-energy trapped protons. In order to overcome problems with detector saturation after standard chemical processing, measurement of LET spectrum in the least shielded CR-39 PNTD layer (0.005 g/cm2 Al) was carried out using an atomic force microscope. c2002 Elsevier Science Ltd. All rights reserved.

Passive dosimetry aboard the Mir Orbital Station: external measurements

NASA Technical Reports Server (NTRS)

Benton, E. R.; Benton, E. V.; Frank, A. L.

2002-01-01

This paper reports results from the first measurements made on the exterior of a LEO spacecraft of mean dose equivalent rate and average quality factor as functions of shielding depth for shielding less than 1 g/cm2 Al equivalent. Two sets of measurements were made on the outside of the Mir Orbital Station; one near solar maximum in June 1991 and one near solar minimum in 1997. Absorbed dose was measured using stacks of TLDs. LET spectrum from charged particles of LET infinity H2O > o r= 5keV/micrometers was measured using stacks of CR-39 PNTDs. Results from the TLD and PNTD measurements at a given shielding depth were combined to yield mean total dose rate, mean dose equivalent rate, and average quality factor. Measurements made near solar maximum tend to be greater than those made during solar minimum. Both mean dose rate and mean dose equivalent rate decrease by nearly four orders of magnitude within the first g/cm2 shielding illustrating the attenuation of both trapped electrons and low-energy trapped protons. In order to overcome problems with detector saturation after standard chemical processing, measurement of LET spectrum in the least shielded CR-39 PNTD layer (0.005 g/cm2 Al) was carried out using an atomic force microscope. c2002 Elsevier Science Ltd. All rights reserved.

Radiobiological equivalent of low/high dose rate brachytherapy and evaluation of tumor and normal responses to the dose.

PubMed

Manimaran, S

2007-06-01

The aim of this study was to compare the biological equivalent of low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy in terms of the more recent linear quadratic (LQ) model, which leads to theoretical estimation of biological equivalence. One of the key features of the LQ model is that it allows a more systematic radiobiological comparison between different types of treatment because the main parameters alpha/beta and micro are tissue-specific. Such comparisons also allow assessment of the likely change in the therapeutic ratio when switching between LDR and HDR treatments. The main application of LQ methodology, which focuses on by increasing the availability of remote afterloading units, has been to design fractionated HDR treatments that can replace existing LDR techniques. In this study, with LDR treatments (39 Gy in 48 h) equivalent to 11 fractions of HDR irradiation at the experimental level, there are increasing reports of reproducible animal models that may be used to investigate the biological basis of brachytherapy and to help confirm theoretical predictions. This is a timely development owing to the nonavailability of sufficient retrospective patient data analysis. It appears that HDR brachytherapy is likely to be a viable alternative to LDR only if it is delivered without a prohibitively large number of fractions (e.g., fewer than 11). With increased scientific understanding and technological capability, the prospect of a dose equivalent to HDR brachytherapy will allow greater utilization of the concepts discussed in this article.

Space radiation dose estimates on the surface of Mars

NASA Technical Reports Server (NTRS)

Simonsen, Lisa C.; Nealy, John E.; Townsend, Lawrence W.; Wilson, John W.

1990-01-01

The Langley cosmic ray transport code and the Langley nucleon transport code (BRYNTRN) are used to quantify the transport and attenuation of galactic cosmic rays (GCR) and solar proton flares through the Martian atmosphere. Surface doses are estimated using both a low density and a high density carbon dioxide model of the atmosphere which, in the vertical direction, provides a total of 16 g/sq cm and 22 g/sq cm of protection, respectively. At the Mars surface during the solar minimum cycle, a blood-forming organ (BFO) dose equivalent of 10.5 to 12 rem/yr due to galactic cosmic ray transport and attenuation is calculated. Estimates of the BFO dose equivalents which would have been incurred from the three large solar flare events of August 1972, November 1960, and February 1956 are also calculated at the surface. Results indicate surface BFO dose equivalents of approximately 2 to 5, 5 to 7, and 8 to 10 rem per event, respectively. Doses are also estimated at altitudes up to 12 km above the Martian surface where the atmosphere will provide less total protection.

SU-E-CAMPUS-T-05: Validation of High-Resolution 3D Patient QA for Proton Pencil Beam Scanning and IMPT by Polymer Gel Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardin, A; Avery, S; Ding, X

2014-06-15

Purpose: Validation of high-resolution 3D patient QA for proton pencil beam scanning and IMPT by polymer gel dosimetry. Methods: Four BANG3Pro polymer gel dosimeters (manufactured by MGS Research Inc, Madison, CT) were used for patient QA at the Robert's Proton Therapy Center (RPTC, Philadelphia, PA). All dosimeters were sealed in identical thin-wall Pyrex glass spheres. Each dosimeter contained a set of markers for 3D registration purposes. The dosimeters were mounted in a consistent and reproducible manner using a custom build holder. Two proton pencil beam scanning plans were designed using Varian Eclipse™ treatment planning system: 1) A two-field intensity modulatedmore » proton therapy (IMPT) plan and 2) one single field uniform dose (SFUD) plan. The IMPT fields were evaluated as a composite plan and individual fields, the SFUD plan was delivered as a single field plan.Laser CT scanning was performed using the manufacturer's OCTOPUS-IQ axial transmission laser CT scanner using a 1 mm slice thickness. 3D registration, analysis, and OD/cm to absorbed dose calibrations were perfomed using DICOM RT-Dose and CT files, and software developed by the manufacturer. 3D delta index, a metric equivalent to the gamma tool, was used for dose comparison. Results: Very good agreement with single IMPT fields and with SFUD was obtained. Composite IMPT fields had a less satisfactory agreement. The single fields had 3D delta index passing rates (3% dose difference, 3 mm DTA) of 98.98% and 94.91%. The composite 3D delta index passing rate was 80.80%. The SFUD passing rate was 93.77%. Required shifts of the dose distributions were less than 4 mm. Conclusion: A formulation of the BANG3Pro polymer gel dosimeter, suitable for 3D QA of proton patient plans is established and validated. Likewise, the mailed QA analysis service provided by the manufacturer is a practical option when required resources are unavailable. We fully disclose that the subject of this research regards a production of MGS Research, Inc.« less

Calculated organ doses for Mayak production association central hall using ICRP and MCNP.

PubMed

Choe, Dong-Ok; Shelkey, Brenda N; Wilde, Justin L; Walk, Heidi A; Slaughter, David M

2003-03-01

As part of an ongoing dose reconstruction project, equivalent organ dose rates from photons and neutrons were estimated using the energy spectra measured in the central hall above the graphite reactor core located in the Russian Mayak Production Association facility. Reconstruction of the work environment was necessary due to the lack of personal dosimeter data for neutrons in the time period prior to 1987. A typical worker scenario for the central hall was developed for the Monte Carlo Neutron Photon-4B (MCNP) code. The resultant equivalent dose rates for neutrons and photons were compared with the equivalent dose rates derived from calculations using the conversion coefficients in the International Commission on Radiological Protection Publications 51 and 74 in order to validate the model scenario for this Russian facility. The MCNP results were in good agreement with the results of the ICRP publications indicating the modeling scenario was consistent with actual work conditions given the spectra provided. The MCNP code will allow for additional orientations to accurately reflect source locations.

Comparison of Organ Dosimetry for Astronaut Phantoms: Earth-Based vs. Microgravity-Based Anthropometry and Body Positioning

NASA Technical Reports Server (NTRS)

VanBaalen, Mary; Bahadon, Amir; Shavers, Mark; Semones, Edward

2011-01-01

The purpose of this study is to use NASA radiation transport codes to compare astronaut organ dose equivalents resulting from solar particle events (SPE), geomagnetically trapped protons, and free-space galactic cosmic rays (GCR) using phantom models representing Earth-based and microgravity-based anthropometry and positioning. Methods: The Univer sity of Florida hybrid adult phantoms were scaled to represent male and female astronauts with 5th, 50th, and 95th percentile heights and weights as measured on Earth. Another set of scaled phantoms, incorporating microgravity-induced changes, such as spinal lengthening, leg volume loss, and the assumption of the neutral body position, was also created. A ray-tracer was created and used to generate body self-shielding distributions for dose points within a voxelized phantom under isotropic irradiation conditions, which closely approximates the free-space radiation environment. Simplified external shielding consisting of an aluminum spherical shell was used to consider the influence of a spacesuit or shielding of a hull. These distributions were combined with depth dose distributions generated from the NASA radiation transport codes BRYNTRN (SPE and trapped protons) and HZETRN (GCR) to yield dose equivalent. Many points were sampled per organ. Results: The organ dos e equivalent rates were on the order of 1.5-2.5 mSv per day for GCR (1977 solar minimum) and 0.4-0.8 mSv per day for trapped proton irradiation with shielding of 2 g cm-2 aluminum equivalent. The organ dose equivalents for SPE irradiation varied considerably, with the skin and eye lens having the highest organ dose equivalents and deep-seated organs, such as the bladder, liver, and stomach having the lowest. Conclus ions: The greatest differences between the Earth-based and microgravity-based phantoms are observed for smaller ray thicknesses, since the most drastic changes involved limb repositioning and not overall phantom size. Improved self-shielding models reduce the overall uncertainty in organ dosimetry for mission-risk projections and assessments for astronauts

A multicenter dose-escalation study of the analgesic and adverse effects of an oral cannabis extract (Cannador) for postoperative pain management.

PubMed

Holdcroft, Anita; Maze, Mervyn; Doré, Caroline; Tebbs, Susan; Thompson, Simon

2006-05-01

Cannabinoids have dose-related antinociceptive effects in animals. This clinical study aimed to investigate whether a single oral dose of cannabis plant extract (Cannador; Institute for Clinical Research, IKF, Berlin, Germany) could provide pain relief with minimal side effects for postoperative pain. Patients (aged 18-75 yr) were recruited and consented before surgery if patient-controlled analgesia was planned for provision of postoperative pain relief. Each patient received a single dose of 5, 10, or 15 mg Cannador if he or she had at least moderate pain after stopping patient-controlled analgesia. Starting with 5 mg, dose escalation was based on the number of patients requesting rescue analgesia and adverse effects. Pain relief, pain intensity, and side effects were recorded over 6 h and analyzed using tests for trend with dose. Rescue analgesia was requested by all 11 patients (100%) receiving 5 mg, 15 of 30 patient (50%) receiving 10 mg, and 6 of 24 patients (25%) receiving 15 mg Cannador (log rank test for trend in time to rescue analgesia with dose P < 0.001). There were also significant trends across the escalating dose groups for decreasing pain intensity at rest (P = 0.01), increasing sedation (P = 0.03), and more adverse events (P = 0.002). The number needed to treat to prevent one rescue analgesia request for the 10-mg and 15-mg doses, relative to 5 mg, were 2.0 (95% confidence interval, 1.5-3.1) and 1.3 (95% confidence interval, 1.1-1.7), respectively. The study was terminated because of a serious vasovagal adverse event in a patient receiving 15 mg. These significant dose-related improvements in rescue analgesia requirements in the 10 mg and 15 mg groups provide a number needed to treat that is equivalent to many routinely used analgesics without frequent adverse effects.

The radiation dose from a proposed measurement of arsenic and selenium in human skin

NASA Astrophysics Data System (ADS)

Gherase, Mihai R.; Mader, Joanna E.; Fleming, David E. B.

2010-09-01

Dose measurements following 10 min irradiations with a portable x-ray fluorescence spectrometer composed of a miniature x-ray tube and a silicon PiN diode detector were performed using thermoluminescent dosimeters consisting of LiF:Mg,Ti chips of 3 mm diameter and 0.4 mm thickness. The table-top setup of the spectrometer was used for all measurements. The setup included a stainless steel lid which served as a radiation shield. Two rectangular polyethylene skin/soft tissue phantoms with two cylindrical plaster of Paris bone phantoms were used to study the effect of x-ray beam attenuation and backscatter on the measured dose. Eight different irradiation experiments were performed. The average dose rate values measured with TLD chips within a 1 × 1 cm2 area were between 4.8 and 12.8 mGy min-1. The equivalent dose for a 1 × 1 cm2 skin area was estimated to be 13.2 mSv. The maximum measured dose rate values with a single TLD chip were between 7.5 and 25.1 mGy min-1. The effective dose corresponding to a proposed arsenic/selenium skin measurement was estimated to be 0.13 µSv for a 2 min irradiation.

A comparative study of space radiation organ doses and associated cancer risks using PHITS and HZETRN.

PubMed

Bahadori, Amir A; Sato, Tatsuhiko; Slaba, Tony C; Shavers, Mark R; Semones, Edward J; Van Baalen, Mary; Bolch, Wesley E

2013-10-21

NASA currently uses one-dimensional deterministic transport to generate values of the organ dose equivalent needed to calculate stochastic radiation risk following crew space exposures. In this study, organ absorbed doses and dose equivalents are calculated for 50th percentile male and female astronaut phantoms using both the NASA High Charge and Energy Transport Code to perform one-dimensional deterministic transport and the Particle and Heavy Ion Transport Code System to perform three-dimensional Monte Carlo transport. Two measures of radiation risk, effective dose and risk of exposure-induced death (REID) are calculated using the organ dose equivalents resulting from the two methods of radiation transport. For the space radiation environments and simplified shielding configurations considered, small differences (<8%) in the effective dose and REID are found. However, for the galactic cosmic ray (GCR) boundary condition, compensating errors are observed, indicating that comparisons between the integral measurements of complex radiation environments and code calculations can be misleading. Code-to-code benchmarks allow for the comparison of differential quantities, such as secondary particle differential fluence, to provide insight into differences observed in integral quantities for particular components of the GCR spectrum.

A comparative study of space radiation organ doses and associated cancer risks using PHITS and HZETRN

NASA Astrophysics Data System (ADS)

Bahadori, Amir A.; Sato, Tatsuhiko; Slaba, Tony C.; Shavers, Mark R.; Semones, Edward J.; Van Baalen, Mary; Bolch, Wesley E.

2013-10-01

NASA currently uses one-dimensional deterministic transport to generate values of the organ dose equivalent needed to calculate stochastic radiation risk following crew space exposures. In this study, organ absorbed doses and dose equivalents are calculated for 50th percentile male and female astronaut phantoms using both the NASA High Charge and Energy Transport Code to perform one-dimensional deterministic transport and the Particle and Heavy Ion Transport Code System to perform three-dimensional Monte Carlo transport. Two measures of radiation risk, effective dose and risk of exposure-induced death (REID) are calculated using the organ dose equivalents resulting from the two methods of radiation transport. For the space radiation environments and simplified shielding configurations considered, small differences (<8%) in the effective dose and REID are found. However, for the galactic cosmic ray (GCR) boundary condition, compensating errors are observed, indicating that comparisons between the integral measurements of complex radiation environments and code calculations can be misleading. Code-to-code benchmarks allow for the comparison of differential quantities, such as secondary particle differential fluence, to provide insight into differences observed in integral quantities for particular components of the GCR spectrum.

Experimental validation of a deforming grid 4D dose calculation for PBS proton therapy.

PubMed

Krieger, Miriam; Klimpki, Grischa; Fattori, Giovanni; Hrbacek, Jan; Oxley, David; Safai, Sairos; Weber, Damien C; Lomax, Antony J; Zhang, Ye

2018-03-01

The aim of this study was to verify the temporal accuracy of the estimated dose distribution by a 4D dose calculation (4DDC) in comparison to measurements. A single-field plan (0.6 Gy), optimised for a liver patient case (CTV volume: 403cc), was delivered to a homogeneous PMMA phantom and measured by a high resolution scintillating-CCD system at two water equivalent depths. Various motion scenarios (no motion and motions with amplitude of 10 mm and two periods: 3.7 s and 4.4 s) were simulated using a 4D Quasar phantom and logged by an optical tracking system in real-time. Three motion mitigation approaches (single delivery, 6[Formula: see text] layered and volumetric rescanning) were applied, resulting in 10 individual measurements. 4D dose distributions were retrospectively calculated in water by taking into account the delivery log files (retrospective) containing information on the actually delivered spot positions, fluences, and time stamps. Moreover, in order to evaluate the sensitivity of the 4DDC inputs, the corresponding prospective 4DDCs were performed as a comparison, using the estimated time stamps of the spot delivery and repeated periodical motion patterns. 2D gamma analyses and dose-difference-histograms were used to quantify the agreement between measurements and calculations for all pixels with [Formula: see text]5% of the maximum calculated dose. The results show that a mean gamma score of 99.2% with standard deviation 1.0% can be achieved for 3%/3 mm criteria and all scenarios can reach a score of more than 95%. The average area with more than 5% dose difference was 6.2%. Deviations due to input uncertainties were obvious for single scan deliveries but could be smeared out once rescanning was applied. Thus, the deforming grid 4DDC has been demonstrated to be able to predict the complex patterns of 4D dose distributions for PBS proton therapy with high dosimetric and geometric accuracy, and it can be used as a valid clinical tool for 4D treatment planning, motion mitigation selection, and eventually 4D optimisation applications if the correct temporal information is available.

Experimental validation of a deforming grid 4D dose calculation for PBS proton therapy

NASA Astrophysics Data System (ADS)

Krieger, Miriam; Klimpki, Grischa; Fattori, Giovanni; Hrbacek, Jan; Oxley, David; Safai, Sairos; Weber, Damien C.; Lomax, Antony J.; Zhang, Ye

2018-03-01

The aim of this study was to verify the temporal accuracy of the estimated dose distribution by a 4D dose calculation (4DDC) in comparison to measurements. A single-field plan (0.6 Gy), optimised for a liver patient case (CTV volume: 403cc), was delivered to a homogeneous PMMA phantom and measured by a high resolution scintillating-CCD system at two water equivalent depths. Various motion scenarios (no motion and motions with amplitude of 10 mm and two periods: 3.7 s and 4.4 s) were simulated using a 4D Quasar phantom and logged by an optical tracking system in real-time. Three motion mitigation approaches (single delivery, 6× layered and volumetric rescanning) were applied, resulting in 10 individual measurements. 4D dose distributions were retrospectively calculated in water by taking into account the delivery log files (retrospective) containing information on the actually delivered spot positions, fluences, and time stamps. Moreover, in order to evaluate the sensitivity of the 4DDC inputs, the corresponding prospective 4DDCs were performed as a comparison, using the estimated time stamps of the spot delivery and repeated periodical motion patterns. 2D gamma analyses and dose-difference-histograms were used to quantify the agreement between measurements and calculations for all pixels with > 5% of the maximum calculated dose. The results show that a mean gamma score of 99.2% with standard deviation 1.0% can be achieved for 3%/3 mm criteria and all scenarios can reach a score of more than 95%. The average area with more than 5% dose difference was 6.2%. Deviations due to input uncertainties were obvious for single scan deliveries but could be smeared out once rescanning was applied. Thus, the deforming grid 4DDC has been demonstrated to be able to predict the complex patterns of 4D dose distributions for PBS proton therapy with high dosimetric and geometric accuracy, and it can be used as a valid clinical tool for 4D treatment planning, motion mitigation selection, and eventually 4D optimisation applications if the correct temporal information is available.

SU-F-T-625: Optimal Treatment Planning Strategy Among Arc Arrangements for Prostate SBRT with VMAT Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, J; Kim, J; Eom, K

Purpose: The purpose of this study is to determine the optimal treatment planning strategy among the different arc arrangements for prostate stereotactic body radiotherapy (SBRT) plans with volumetric modulated arc therapy (VMAT). Methods: Ten patients with prostate cancer were selected. The SBRT-VMAT plans for each patient were generated with single-full (181° to 179°; 1FA), single-partial (240° to 120°; 1PA), double-full (181° to 179° and 179° to 181°; 2FA), and double-partial (240° to 120° and 120° to 240°; 2PA) arc arrangements. The prescription dose was 42.7 Gy in 7 fractions. Dose distribution was calculated using a 10-MV flattening-filter-free beam and themore » Acuros XB algorithm. Dosimetric parameters of target volume and organs at risk (OARs) were evaluated from cumulative dose-volume histograms on prostate SBRT-VMAT plans between single-arc (1FA and 1PA) and double-arc (2FA and 2PA) arrangements. Results: All plans using four arc arrangements were highly conformal with conformity index (CI)<1.05 and conformation number (CN)=0.91, and the doses to target volume were homogeneous (homogeneity index (HI)= 0.09 0.12). Pertaining to the dose to the OARs, there were significant differences in the rectum, left and right femoral head doses while having no difference in the bladder dose. The partial-arc (1PA and 2PA) had relatively high reductions for the mean rectum dose compared to full-arc (1FA and 2FA). The near-to-maximum dose (D2%) and mean dose of the left and right femoral head were always lower on prostate SBRT-VMAT plan using the full-arc, when compared to the partial-arc arrangement. Conclusion: This study confirmed that prostate SBRT-VMAT using 1PA was feasible fast delivery time and produced equivalent target coverage and better rectum sparing, although the D2% and mean dose of the left and right femoral head increased slightly. Therefore, the results of this study suggest that the use of 1PA is an attractive choice for delivering prostate SBRT-VMAT.« less

SU-F-T-637: Single-Isocenter Versus Multiple-Isocenter VMAT SRS for Unusual Multiple Metastasis Case with Two Widely Separated Lesions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, EM; Popple, RA; Fiveash, JB

Purpose: Single-isocenter (SI) volumetric modulated arc therapy has been shown to be an effective and efficient approach to multiple metastasis radiosurgery. However, certain extreme cases raise the question of whether multiple-isocenter (MI) approaches can still generate superior plans. In this study, we ask this question with respect to a clinical case with two very widely separated lesions. Methods: A patient with two widely separated (d = 12cm) tumors was treated with SI-VMAT SRS using 10MV flattening filter free (FFF) beam with high-definition multi-leaf collimator (HD-MLC, 2.5/5mm) in two non-coplanar arcs using concentric rings to enforce steep gradient. Because of lesionmore » positioning with respect to collimator angle selection, lesions were treated by 5mm leaves. We re-planned the case with a congruent arc arrangement but separate isocenter for each lesion. In this manner, lesions were treated by 2.5mm leaves. Conformity index (CI), V50%, and mean brain dose were compared. Results: Neither conformity (CI-SI = 1.12, CI-MI = 1.08) nor V50% (V50%-SI =8.82cc, V50%-MI =8.81cc) were improved by utilizing a separate isocenter for each lesion. Mean brain dose was slightly reduced (dmean-SI = 118.4 cGy, dmean-MI = 88.7 cGy) by using multiple isocenters. Conclusion: For this case with a lesion at the apex of the brain and another distantly located at the base of skull, employing a separate isocenter for each target did not meaningfully improve plan quality. Single-isocenter VMAT has been shown feasible and equivalent to multiple-isocenter VMAT for multiple metastasis cases in general. In this extreme case, single- and multiple- isocenter VMAT were also equivalent. If rotational setup errors are appropriately corrected, the increased delivery efficiency of the single-isocenter approach renders it preferable to the multiple isocenter approach. Dr’s Thomas, Popple, and Fiveash have all received honoraria from Varian Medical Systems for discussing their experiences with stereotactic radiosurgery.« less

Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices

DOEpatents

Horn, Kevin M.

2013-07-09

A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

Fluence-to-dose conversion coefficients for heavy ions calculated using the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Niita, Koji

2010-04-21

The fluence to organ-absorbed-dose and effective-dose conversion coefficients for heavy ions with atomic numbers up to 28 and energies from 1 MeV/nucleon to 100 GeV/nucleon were calculated using the PHITS code coupled to the ICRP/ICRU adult reference computational phantoms, following the instruction given in ICRP Publication 103 (2007 (Oxford: Pergamon)). The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. The calculation results indicate that the effective dose can generally give a conservative estimation of the effective dose equivalent for heavy-ion exposure, although it is occasionally too conservative especially for high-energy lighter-ion irradiations. It is also found from the calculation that the conversion coefficients for the Q(y)-based effective dose equivalents are generally smaller than the corresponding Q(L)-based values because of the conceptual difference between LET and y as well as the numerical incompatibility between the Q(L) and Q(y) relationships. The calculated data of these dose conversion coefficients are very useful for the dose estimation of astronauts due to cosmic-ray exposure.

Radiation dosimetry measurements with real time radiation monitoring device (RRMD)-II in Space Shuttle STS-79

NASA Technical Reports Server (NTRS)

Sakaguchi, T.; Doke, T.; Hayashi, T.; Kikuchi, J.; Hasebe, N.; Kashiwagi, T.; Takashima, T.; Takahashi, K.; Nakano, T.; Nagaoka, S.;

FDA-sunlamp recommended Maximum Timer Interval And Exposure Schedule: consensus ISO/CIE dose equivalence.

PubMed

Dowdy, John C; Czako, Eugene A; Stepp, Michael E; Schlitt, Steven C; Bender, Gregory R; Khan, Lateef U; Shinneman, Kenneth D; Karos, Manuel G; Shepherd, James G; Sayre, Robert M

2011-09-01

The authors compared calculations of sunlamp maximum exposure times following current USFDA Guidance Policy on the Maximum Timer Interval and Exposure Schedule, with USFDA/CDRH proposals revising these to equivalent erythemal exposures of ISO/CIE Standard Erythema Dose (SED). In 2003, [USFDA/CDRH proposed replacing their unique CDRH/Lytle] erythema action spectrum with the ISO/CIE erythema action spectrum and revising the sunlamp maximum exposure timer to 600 J m(-2) ISO/CIE effective dose, presented as being biologically equivalent. Preliminary analysis failed to confirm said equivalence, indicating instead ∼38% increased exposure when applying these proposed revisions. To confirm and refine this finding, a collaboration of tanning bed and UV lamp manufacturers compiled 89 UV spectra representing a broad sampling of U.S. indoor tanning equipment. USFDA maximum recommended exposure time (Te) per current sunlamp guidance and CIE erythemal effectiveness per ISO/CIE standard were calculated. The CIE effective dose delivered per Te averaged 456 J(CIE) m(-2) (SD = 0.17) or ∼4.5 SED. The authors found that CDRH's proposed 600 J(CIE) m(-2) recommended maximum sunlamp exposure exceeds current Te erythemal dose by ∼33%. The current USFDA 0.75 MED initial exposure was ∼0.9 SED, consistent with 1.0 SED initial dose in existing international sunlamp standards. As no sunlamps analyzed exceeded 5 SED, a revised maximum exposure of 500 J(CIE) m(-2) (∼80% of CDRH's proposal) should be compatible with existing tanning equipment. A tanning acclimatization schedule is proposed beginning at 1 SED thrice-weekly, increasing uniformly stepwise over 4 wk to a 5 SED maximum exposure in conjunction with a tan maintenance schedule of twice-weekly 5 SED sessions, as biologically equivalent to current USFDA sunlamp policy.

SU-E-T-495: Influence of Reduced Target-To-Nozzle Distance On Secondary Neutron Dose Equivalent in Proton and Carbon Ion Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, Y; Shahnazi, K; Wang, W

Purpose: Ion beams have an unavoidable lateral spread due to nuclear interactions interacting with the air and monitoring systems. To minimize this spread, the distance between the nozzle and the patient should be kept as small as possible.The purpose of this work was to determine the impact of the target-to-nozzle distance reduction on the secondary neutron dose equivalent in proton and carbon ion radiotherapy. Methods: In this study, abdominal and head phantoms were scanned with our CT scanner. Cubical targets with side lengths of 3 cm to 10 cm and 1 cm to 5 cm were drawn in the abdominalmore » and head phantoms respectively. Two intensity-modulated plans were made for each phantom and ion. The first of these plans placed the target at the isocenter while the other shifted the phantom 30 cm towards the nozzle. The plans at both phantom locations were optimized to provide identical dose coverage to the PTVs.Secondary neutron dose equivalent at 50 cm lateral to the center of target. Results: The neutron dose equivalent was higher for the larger field size from 0.25µSv per Gy (RBE) to 72µSv per Gy (RBE). The neutron dose equivalent was smaller when the phantom was placed at the upstream target location versus at the isocenter location by 8.9% to 10.4% and 11.0% to 22.1% for proton plans of the abdominal and head phantoms respectively. Differences for carbon plans with different target-to-nozzle locations were less than 3% for both phantoms. Conclusion: A reduction of target-to-nozzle distance can lead to benefits for proton radiotherapy. In this study, a reduction of secondary neutron dose equivalent was found for proton plans with a smaller target-to-nozzle distance. A greater impact was found for a head phantom with a smaller field size; however, a reduction of the target-to-nozzle distance had little effect for carbon therapy.« less

Measurement of neutron dose equivalent outside and inside of the treatment vault of GRID therapy.

PubMed

Wang, Xudong; Charlton, Michael A; Esquivel, Carlos; Eng, Tony Y; Li, Ying; Papanikolaou, Nikos

2013-09-01

To evaluate the neutron and photon dose equivalent rates at the treatment vault entrance (Hn,D and HG), and to study the secondary radiation to the patient in GRID therapy. The radiation activation on the grid was studied. A Varian Clinac 23EX accelerator was working at 18 MV mode with a grid manufactured by .decimal, Inc. The Hn,D and HG were measured using an Andersson-Braun neutron REM meter, and a Geiger Müller counter. The radiation activation on the grid was measured after the irradiation with an ion chamber γ-ray survey meter. The secondary radiation dose equivalent to patient was evaluated by etched track detectors and OSL detectors on a RANDO(®) phantom. Within the measurement uncertainty, there is no significant difference between the Hn,D and HG with and without a grid. However, the neutron dose equivalent to the patient with the grid is, on average, 35.3% lower than that without the grid when using the same field size and the same amount of monitor unit. The photon dose equivalent to the patient with the grid is, on average, 44.9% lower. The measured average half-life of the radiation activation in the grid is 12.0 (± 0.9) min. The activation can be categorized into a fast decay component and a slow decay component with half-lives of 3.4 (± 1.6) min and 15.3 (± 4.0) min, respectively. There was no detectable radioactive contamination found on the surface of the grid through a wipe test. This work indicates that there is no significant change of the Hn,D and HG in GRID therapy, compared with a conventional external beam therapy. However, the neutron and scattered photon dose equivalent to the patient decrease dramatically with the grid and can be clinical irrelevant. Meanwhile, the users of a grid should be aware of the possible high dose to the radiation worker from the radiation activation on the surface of the grid. A delay in handling the grid after the beam delivery is suggested.

Human response to high-background radiation environments on Earth and in space

NASA Astrophysics Data System (ADS)

Durante, M.; Manti, L.

2008-09-01

The main long-term objective of the space exploration program is the colonization of the planets of the Solar System. The high cosmic radiation equivalent dose rate represents an inescapable problem for the safe establishment of permanent human settlements on these planets. The unshielded equivalent dose rate on Mars ranges between 100 and 200 mSv/year, depending on the Solar cycle and altitude, and can reach values as high as 360 mSv/year on the Moon. The average annual effective dose on Earth is about 3 mSv, nearly 85% of which comes from natural background radiation, reduced to less than 1 mSv if man-made sources and the internal exposure to Rn daughters are excluded. However, some areas on Earth display anomalously high levels of background radiation, as is the case with thorium-rich monazite bearing sand deposits where values 200 400 times higher than the world average can be found. About 2% of the world’s population live above 3 km and receive a disproportionate 10% of the annual effective collective dose due to cosmic radiation, with a net contribution to effective dose by the neutron component which is 3 4 fold that at sea level. Thus far, epidemiological studies have failed to show any adverse health effects in the populations living in these terrestrial high-background radiation areas (HBRA), which provide an unique opportunity to study the health implications of an environment that, as closely as possibly achievable on Earth, resembles the chronic exposure of future space colonists to higher-than-normal levels of ionizing radiation. Chromosomal aberrations in the peripheral blood lymphocytes from the HBRA residents have been measured in several studies because chromosomal damage represents an early biomarker of cancer risk. Similar cytogenetic studies have been recently performed in a cohort of astronauts involved in single or repeated space flights over many years. The cytogenetic findings in populations exposed to high dose-rate background radiation on Earth or in space will be discussed.

Non-steroidal anti-inflammatory drugs and gastroprotection with proton pump inhibitors: a focus on ketoprofen/omeprazole.

PubMed

Gigante, Antonio; Tagarro, Ignacio

2012-04-01

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed agents for rheumatic disorders such as osteoarthritis (OA), rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Despite the known association between NSAID use and gastropathy, however, only around one-third of patients at risk of NSAID-induced gastrointestinal toxicity receive adequate gastroprotection, and as many as 44% of these patients are non-adherent. We review the co-prescription of proton pump inhibitors (PPIs) for the prevention of NSAID-induced gastropathy, with a particular focus on the first fixed-dose NSAID/PPI formulation: ketoprofen/omeprazole modified-release capsules. The ketoprofen/omeprazole fixed-dose combination is available in doses of 100 mg/20 mg, 150 mg/20 mg or 200 mg/20 mg as a single capsule for once-daily administration. Ketoprofen monotherapy has been shown to be generally equivalent to other NSAIDs when used in the treatment of OA. In RA, ketoprofen has demonstrated equivalent efficacy to diclofenac, indometacin, piroxicam, aceclofenac, phenylbutazone, naproxen and flurbiprofen. Studies comparing ketoprofen with ibuprofen and sulindac in patients with RA have, in general, favoured ketoprofen. Studies in AS have generally reported similar efficacy between ketoprofen and phenylbutazone and pirprofen. Prophylaxis with omeprazole is effective for the prevention of gastroduodenal ulcers, maintenance of remission and alleviation of dyspeptic symptoms in NSAID recipients. Omeprazole is well tolerated, and adverse events are generally gastrointestinal in nature. The fixed-dose combination of ketoprofen and omeprazole has demonstrated bioequivalence to the respective monotherapies. The incidence of digestive symptoms and the need for dose reduction was reported to be lower with the combination than with its components. Ketoprofen/omeprazole modified-release capsules are the first fixed-dose NSAID/PPI formulation to be approved. This formulation ensures compliance with the gastroprotective prophylaxis, as whenever the NSAID is taken, the PPI is co-administered. Additionally, the once-daily formulation has the potential to improve adherence to anti-inflammatory therapy. © 2012 Adis Data Information BV. All rights reserved.

Investigation on using high-energy proton beam for total body irradiation (TBI).

PubMed

Zhang, Miao; Qin, Nan; Jia, Xun; Zou, Wei J; Khan, Atif; Yue, Ning J

2016-09-08

This work investigated the possibility of using proton beam for total body irradia-tion (TBI). We hypothesized the broad-slow-rising entrance dose from a monoen-ergetic proton beam can deliver a uniform dose to patient with varied thickness. Comparing to photon-based TBI, it would not require any patient-specific com-pensator or beam spoiler. The hypothesis was first tested by simulating 250 MeV, 275 MeV, and 300 MeV protons irradiating a wedge-shaped water phantom in a paired opposing arrangement using Monte Carlo (MC) method. To allow ± 7.5% dose variation, the maximum water equivalent thickness (WET) of a treatable patient separation was 29 cm for 250 MeV proton, and > 40 cm for 275 MeV and 300 MeV proton. The compared 6 MV photon can only treat patients with up to 15.5 cm water-equivalent separation. In the second step, we simulated the dose deposition from the same beams on a patient's whole-body CT scan. The maximum patient separation in WET was 23 cm. The calculated whole-body dose variations were ± 8.9%, ± 9.0%, ± 9.6%, and ± 14% for 250 MeV proton, 275 MeV proton, 300 MeV proton, and 6 MV photon. At last, we tested the current machine capability to deliver a monoenergetic proton beam with a large uniform field. Experiments were performed on a compact double scattering single-gantry proton system. With its C-shaped gantry design, the source-to-surface distance (SSD) reached 7 m. The measured dose deposition curve had 22 cm relatively flat entrance region. The full width half maximum field size was measured 105 cm. The current scatter filter had to be redesigned to produce a uniform intensity at such treatment distance. In con-clusion, this work demonstrated the possibility of using proton beam for TBI. The current commercially available proton machines would soon be ready for such task. © 2016 The Authors.

Results of nDOSE and HiDOSE Experiments for Dosimetric Evaluation During STS-134 Mission

NASA Astrophysics Data System (ADS)

Pugliese, M.; Loffredo, F.; Quarto, M.; Roca, V.; Mattone, C.; Borla, O.; Zanini, A.

2014-07-01

HiDOSE (Heavy ion DOSimetry Experiment) and nDOSE (neutron DOSimetry Experiment) experiments conducted as a part of BIOKIS (Biokon in Space) payload were designed to measure the dose equivalent due to charged particles and to neutron field, on the entire energy range, during STS-134 mission. Given the complexity of the radiation field in space environment, dose measurements should be considered an asset of any space mission, and for this reason HiDOSE and nDOSE experiments represent an important contribution to the radiation environment assessment during this mission, a short duration flight. The results of these experiments, obtained using Thermo Luminescence Dosimeters (TLDs) to evaluate the charged particles dosimetry and neutron bubbles dosimeters and stack bismuth track dosimeters for neutron dosimetry, indicate that the dose equivalent rate due to space radiation exposure during the STS-134 mission is in accordance with the results obtained from long duration flights.

Dose conversion coefficients for electron exposure of the human eye lens

NASA Astrophysics Data System (ADS)

Behrens, R.; Dietze, G.; Zankl, M.

2009-07-01

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity Hp(0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity Hp(3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0° and 45° are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

Dose conversion coefficients for electron exposure of the human eye lens.

PubMed

Behrens, R; Dietze, G; Zankl, M

2009-07-07

Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity H(p)(0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity H(p)(3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0 degrees and 45 degrees are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

Measurement of dose distribution in the spherical phantom onboard the ISS-KIBO module -MATROSHKA-R in KIBO-

NASA Astrophysics Data System (ADS)

Kodaira, Satoshi; Kawashima, Hajime; Kurano, Mieko; Uchihori, Yukio; Nikolaev, Igor; Ambrozova, Iva; Kitamura, Hisashi; Kartsev, Ivan; Tolochek, Raisa; Shurshakov, Vyacheslav

The measurement of dose equivalent and effective dose during manned space missions on the International Space Station (ISS) is important for evaluating the risk to astronaut health and safety when exposed to space radiation. The dosimetric quantities are constantly changing and strongly depend on the level of solar activity and the various spacecraft- and orbit-dependent parameters such as the shielding distribution in the ISS module, location of the spacecraft within its orbit relative to the Earth, the attitude (orientation) and altitude. Consequently, the continuous monitoring of dosimetric quantities is required to record and evaluate the personal radiation dose for crew members during spaceflight. The dose distributions in the phantom body and on its surface give crucial information to estimate the dose equivalent in the human body and effective dose in manned space mission. We have measured the absorbed dose and dose equivalent rates using passive dosimeters installed in the spherical phantom in Japanese Experiment Module (“KIBO”) of the ISS in the framework of Matroshka-R space experiment. The exposure duration was 114 days from May 21 to September 12, 2012. The phantom consists of tissue-equivalent material covered with a poncho jacket with 32 pockets on its surface and 20 container rods inside of the phantom. The phantom diameter is 35 cm and the mass is 32 kg. The passive dosimeters consisted of a combination of luminescent detectors of Al _{2}O _{3};C OSL and CaSO _{4}:Dy TLD and CR-39 plastic nuclear track detectors. As one of preliminary results, the dose distribution on the phantom surface measured with OSL detectors installed in the jacket pockets is found to be ranging from 340 muGy/day to 260 muGy/day. In this talk, we will present the detail dose distributions, and variations of LET spectra and quality factor obtained outside and inside of the spherical phantom installed in the ISS-KIBO.

Monte-Carlo Modeling of the Prompt Radiation Emitted by a Nuclear Device in the National Capital Region, Revision 1

DTIC Science & Technology

2016-08-10

Anno, et al. 2003). The asymptomatic level (0.75 Gy) is considered the lower dose threshold of the presence of symptoms from acute radiation ...high probability of acute injury due to prompt radiation (shown in yellow, > 0.75-Gy equivalent dose) and low probability of acute injury from prompt...of an urban nuclear-weapon detonation as associated with the possibility of acute , deterministic radiation effects. Equivalent-dose calculations for

Radiation Exposure of Interventional Radiologists During Computed Tomography Fluoroscopy-Guided Renal Cryoablation and Lung Radiofrequency Ablation: Direct Measurement in a Clinical Setting.

PubMed

Matsui, Yusuke; Hiraki, Takao; Gobara, Hideo; Iguchi, Toshihiro; Fujiwara, Hiroyasu; Kawabata, Takahiro; Yamauchi, Takatsugu; Yamaguchi, Takuya; Kanazawa, Susumu

2016-06-01

Computed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking. Radiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator's finger skin was measured using thermoluminescent dosimeter rings. The mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator's finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA. Radiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsui, Yusuke, E-mail: wckyh140@yahoo.co.jp; Hiraki, Takao, E-mail: takaoh@tc4.so-net.ne.jp; Gobara, Hideo, E-mail: gobara@cc.okayama-u.ac.jp

IntroductionComputed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking.Materials and MethodsRadiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator’s finger skinmore » was measured using thermoluminescent dosimeter rings.ResultsThe mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator’s finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA.ConclusionRadiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.« less

Effective radiation dose of ProMax 3D cone-beam computerized tomography scanner with different dental protocols.

PubMed

Qu, Xing-min; Li, Gang; Ludlow, John B; Zhang, Zu-yan; Ma, Xu-chen

2010-12-01

The aim of this study was to compare effective doses resulting from different scan protocols for cone-beam computerized tomography (CBCT) using International Commission on Radiological Protection (ICRP) 1990 and 2007 calculations of dose. Average tissue-absorbed dose, equivalent dose, and effective dose for a ProMax 3D CBCT with different dental protocols were calculated using thermoluminescent dosimeter chips in a human equivalent phantom. Effective doses were derived using ICRP 1990 and the superseding 2007 recommendations. Effective doses (ICRP 2007) for default patient sizes from small to large ranged from 102 to 298 μSv. The coefficient of determination (R(2)) between tube current and effective dose (ICRP 2007) was 0.90. When scanning with lower resolution settings, the effective doses were reduced significantly (P < .05). ProMax 3D can provide a wide range of radiation dose levels. Reduction in radiation dose can be achieved when using lower settings of exposure parameters. Copyright © 2010 Mosby, Inc. All rights reserved.

Development of a synthetic single crystal diamond dosimeter for dose measurement of clinical proton beams

NASA Astrophysics Data System (ADS)

Moignier, Cyril; Tromson, Dominique; de Marzi, Ludovic; Marsolat, Fanny; García Hernández, Juan Carlos; Agelou, Mathieu; Pomorski, Michal; Woo, Romuald; Bourbotte, Jean-Michel; Moignau, Fabien; Lazaro, Delphine; Mazal, Alejandro

2017-07-01

The scope of this work was to develop a synthetic single crystal diamond dosimeter (SCDD-Pro) for accurate relative dose measurements of clinical proton beams in water. Monte Carlo simulations were carried out based on the MCNPX code in order to investigate and reduce the dose curve perturbation caused by the SCDD-Pro. In particular, various diamond thicknesses were simulated to evaluate the influence of the active volume thickness (e AV) as well as the influence of the addition of a front silver resin (250 µm in thickness in front of the diamond crystal) on depth-dose curves. The simulations indicated that the diamond crystal alone, with a small e AV of just 5 µm, already affects the dose at Bragg peak position (Bragg peak dose) by more than 2% with respect to the Bragg peak dose deposited in water. The optimal design that resulted from the Monte Carlo simulations consists of a diamond crystal of 1 mm in width and 150 µm in thickness with the front silver resin, enclosed by a water-equivalent packaging. This design leads to a deviation between the Bragg peak dose from the full detector modeling and the Bragg peak dose deposited in water of less than 1.2%. Based on those optimizations, an SCDD-Pro prototype was built and evaluated in broad passive scattering proton beams. The experimental evaluation led to probed SCDD-Pro repeatability, dose rate dependence and linearity, that were better than 0.2%, 0.4% (in the 1.0-5.5 Gy min-1 range) and 0.4% (for dose higher than 0.05 Gy), respectively. The depth-dose curves in the 90-160 MeV energy range, measured with the SCDD-Pro without applying any correction, were in good agreement with those measured using a commercial IBA PPC05 plane-parallel ionization chamber, differing by less than 1.6%. The experimental results confirmed that this SCDD-Pro is suitable for measurements with standard electrometers and that the depth-dose curve perturbation is negligible, with no energy dependence and no significant dose rate dependence.

Development of a synthetic single crystal diamond dosimeter for dose measurement of clinical proton beams.

PubMed

Moignier, Cyril; Tromson, Dominique; de Marzi, Ludovic; Marsolat, Fanny; García Hernández, Juan Carlos; Agelou, Mathieu; Pomorski, Michal; Woo, Romuald; Bourbotte, Jean-Michel; Moignau, Fabien; Lazaro, Delphine; Mazal, Alejandro

2017-07-07

The scope of this work was to develop a synthetic single crystal diamond dosimeter (SCDD-Pro) for accurate relative dose measurements of clinical proton beams in water. Monte Carlo simulations were carried out based on the MCNPX code in order to investigate and reduce the dose curve perturbation caused by the SCDD-Pro. In particular, various diamond thicknesses were simulated to evaluate the influence of the active volume thickness (e AV ) as well as the influence of the addition of a front silver resin (250 µm in thickness in front of the diamond crystal) on depth-dose curves. The simulations indicated that the diamond crystal alone, with a small e AV of just 5 µm, already affects the dose at Bragg peak position (Bragg peak dose) by more than 2% with respect to the Bragg peak dose deposited in water. The optimal design that resulted from the Monte Carlo simulations consists of a diamond crystal of 1 mm in width and 150 µm in thickness with the front silver resin, enclosed by a water-equivalent packaging. This design leads to a deviation between the Bragg peak dose from the full detector modeling and the Bragg peak dose deposited in water of less than 1.2%. Based on those optimizations, an SCDD-Pro prototype was built and evaluated in broad passive scattering proton beams. The experimental evaluation led to probed SCDD-Pro repeatability, dose rate dependence and linearity, that were better than 0.2%, 0.4% (in the 1.0-5.5 Gy min -1 range) and 0.4% (for dose higher than 0.05 Gy), respectively. The depth-dose curves in the 90-160 MeV energy range, measured with the SCDD-Pro without applying any correction, were in good agreement with those measured using a commercial IBA PPC05 plane-parallel ionization chamber, differing by less than 1.6%. The experimental results confirmed that this SCDD-Pro is suitable for measurements with standard electrometers and that the depth-dose curve perturbation is negligible, with no energy dependence and no significant dose rate dependence.

A simple calculation method for determination of equivalent square field.

PubMed

Shafiei, Seyed Ali; Hasanzadeh, Hadi; Shafiei, Seyed Ahmad

2012-04-01

Determination of the equivalent square fields for rectangular and shielded fields is of great importance in radiotherapy centers and treatment planning software. This is accomplished using standard tables and empirical formulas. The goal of this paper is to present a formula based on analysis of scatter reduction due to inverse square law to obtain equivalent field. Tables are published by different agencies such as ICRU (International Commission on Radiation Units and measurements), which are based on experimental data; but there exist mathematical formulas that yield the equivalent square field of an irregular rectangular field which are used extensively in computation techniques for dose determination. These processes lead to some complicated and time-consuming formulas for which the current study was designed. In this work, considering the portion of scattered radiation in absorbed dose at a point of measurement, a numerical formula was obtained based on which a simple formula was developed to calculate equivalent square field. Using polar coordinate and inverse square law will lead to a simple formula for calculation of equivalent field. The presented method is an analytical approach based on which one can estimate the equivalent square field of a rectangular field and may be used for a shielded field or an off-axis point. Besides, one can calculate equivalent field of rectangular field with the concept of decreased scatter radiation with inverse square law with a good approximation. This method may be useful in computing Percentage Depth Dose and Tissue-Phantom Ratio which are extensively used in treatment planning.

Clinical outcomes from an innovative protocol using serial ultrasound imaging and a single MR image to guide brachytherapy for locally advanced cervix cancer.

PubMed

van Dyk, Sylvia; Narayan, Kailash; Bernshaw, David; Kondalsamy-Chennakesavan, Srinivas; Khaw, Pearly; Lin, Ming Yin; Schneider, Michal

The aim of this study was to report clinical outcomes in a series of patients who underwent serial ultrasound and a single MRI to plan and verify intracavitary brachytherapy. Data for patients who were referred for curative intent radiotherapy for International Federation of Gynecology and Obstetrics (FIGO) Stage 1-1V cervix cancer between January 2007 and March 2012 were analyzed. All patients received external beam radiotherapy with concurrent chemotherapy and sequential high-dose rate brachytherapy. Brachytherapy was planned and verified using serial ultrasound imaging and a single MRI. Data from 191 patients were available for analyses. The median (range) followup time was 5.08 (0.25-8.25) years. Five-year local control, failure-free survival, cancer-specific survival, and overall survival were 86%, 57.3%, 70% and 63%, respectively. Mean (standard deviation) combined external beam radiotherapy and brachytherapy target doses, equivalent to doses in 2 Gy fractions were 80.4 Gy10 (3.89), median (range) 80 (49-96) Gy10. Grade 3 or greater gastrointestinal, genitourinary, or vaginal late toxicity occurred in 3%, 1.6%, and 2% of patients, respectively. Survival, patterns of failure, and late complication rates were similar to published series of MRI/CT-based brachytherapy practices. This large study demonstrates that favorable treatment outcomes can be obtained using a pragmatic and innovative combination of ultrasound and MR imaging. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Weighted concentration of sup 137 Cs equivalent in foodstuffs in Kuwait from June 1986 to December 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakir, Y.Y.; Sayed, A.M.; Salem, M.S.

1990-06-01

The weighted monthly concentration of {sup 137}Cs equivalent (WMC) for various types of foodstuffs imported from June 1986 to December 1988 are discussed. The data presented are based on total concentration of {sup 137}Cs equivalent. The concentration was found below the disqualifying level applied in Kuwait. The radioactive contamination was higher in milk and baby milk relative to other types of foodstuffs. The calculation of Kuwait's disqualifying levels are based on the annual dose equivalent of 1 mSv (100 mrem). The measured WMC for most types of foodstuffs represents a small fraction to the annual dose limit recommended for themore » general public.« less

Direct-detection EPID dosimetry: investigation of a potential clinical configuration for IMRT verification.

PubMed

Vial, Philip; Gustafsson, Helen; Oliver, Lyn; Baldock, Clive; Greer, Peter B

2009-12-07

The routine use of electronic portal imaging devices (EPIDs) as dosimeters for radiotherapy quality assurance is complicated by the non-water equivalence of the EPID's dose response. A commercial EPID modified to a direct-detection configuration was previously demonstrated to provide water-equivalent dose response with d(max) solid water build-up and 10 cm solid water backscatter. Clinical implementation of the direct EPID (dEPID) requires a design that maintains the water-equivalent dose response, can be incorporated onto existing EPID support arms and maintains sufficient image quality for clinical imaging. This study investigated the dEPID dose response with different configurations of build-up and backscatter using varying thickness of solid water and copper. Field size output factors and beam profiles measured with the dEPID were compared with ionization chamber measurements of dose in water for both 6 MV and 18 MV. The dEPID configured with d(max) solid water build-up and no backscatter (except for the support arm) was within 1.5% of dose in water data for both energies. The dEPID was maintained in this configuration for clinical dosimetry and image quality studies. Close agreement between the dEPID and treatment planning system was obtained for an IMRT field with 98.4% of pixels within the field meeting a gamma criterion of 3% and 3 mm. The reduced sensitivity of the dEPID resulted in a poorer image quality based on quantitative (contrast-to-noise ratio) and qualitative (anthropomorphic phantom) studies. However, clinically useful images were obtained with the dEPID using typical treatment field doses. The dEPID is a water-equivalent dosimeter that can be implemented with minimal modifications to the standard commercial EPID design. The proposed dEPID design greatly simplifies the verification of IMRT dose delivery.

Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit

NASA Astrophysics Data System (ADS)

El-Jaby, Samy; Richardson, Richard B.

2015-07-01

Occupational exposures from ionizing radiation are currently regulated for airline travel (<20 km) and for missions to low-Earth orbit (∼300-400 km). Aircrew typically receive between 1 and 6 mSv of occupational dose annually, while aboard the International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit.

Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit.

PubMed

El-Jaby, Samy; Richardson, Richard B

2015-07-01

Occupational exposures from ionizing radiation are currently regulated for airline travel (<20 km) and for missions to low-Earth orbit (∼300-400 km). Aircrew typically receive between 1 and 6 mSv of occupational dose annually, while aboard the International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Pharmacokinetic Interactions between the Hormonal Emergency Contraception, Levonorgestrel (Plan B), and Efavirenz

PubMed Central

Carten, Monica L.; Kiser, Jennifer J.; Kwara, Awewura; Mawhinney, Samantha; Cu-Uvin, Susan

2012-01-01

Objectives. Compare the Plan B levonorgestrel (LNG) area under the concentration- time curve (AUC12) prior to and with efavirenz (EFV). Design. Prospective, open-label, single-arm, equivalence study. Methods. Healthy HIV-negative subjects underwent 12 hr intensive pharmacokinetic (PK) sampling following single dose LNG alone and after 14 days of EFV. Geometric means, Geometric Mean Ratios, and 90% confidence intervals (CI) are reported for PK Parameters. T-tests were utilized. Clinical parameters and liver function tests (LFTs) were assessed. Results. 24 women enrolled and 21 completed the study. With EFV, LNG AUC12 was reduced 56% (95% CI: 49%, 62%) from 42.9 to 17.8 ng∗hr/mL, and maximum concentration (Cmax⁡) was reduced 41% (95% CI: 33%, 50%) from 8.4 to 4.6 ng/mL. LNG was well tolerated with no grade 3 or 4 treatment-related toxicities. Conclusions. EFV significantly reduced LNG exposures. Higher LNG doses may be required with EFV. These results reinforce the importance of effective contraception in women taking EFV. PMID:22536010

Relative bioavailability of rifampicin, isoniazid and ethambutol from a combination tablet vs. concomitant administration of a capsule containing rifampicin and a tablet containing isoniazid and ethambutol.

PubMed

Schall, R; Müller, F O; Duursema, L; Groenewoud, G; Hundt, H K; Middle, M V; Mogilnicka, E M; Swart, K J

1995-11-01

Twenty male volunteers who were slow metabolisers of isoniazid, completed this single-blind, single-dose, randomised, cross-over study to compare the bioavailability of rifampicin (CAS 13292-46-1), isoniazid (CAS 54-85-3) and ethambutol (CAS 1070-11-7) from Myrin tablets (test preparation) with the bioavailability of these drugs from a combination of capsules containing rifampicin and tablets containing isoniazid and ethambutol (reference). There were 2 treatment periods and on clinic days volunteers were given either the reference (300 mig rifampicin plus 200 mg isoniazid and 600 mg ethambutol HCl), or the test preparation (300 mg rifampicin, 150 mg isoniazid and 600 mg ethambutol HCl). Serial blood samples were drawn from the volunteers and rifampicin, isoniazid and ethambutol assays were performed. The results of this study indicate that the test preparation is equivalent to the reference with respect to both the rate and the extent of absorption of rifampicin, isoniazid (after adjustment for the different doses of isoniazid and ethambutol).

Postradiation hypothyroidism in head and neck cancers: A Department of Veterans Affairs single-institution case-control dosimetry study.

PubMed

Lin, Alexander J; Zhang, Juying; Cho-Lim, Jennie; Inouye, Warren; Lee, Steve P

2018-03-23

We performed a case-control study to characterize the dose-volume relationship and other variables leading to hypothyroidism after head and neck (H&N) cancer radiation therapy (RT) in a homogenous Veterans Affairs (VA) population. All records of patients receiving RT for various H&N cancers at a single VA medical center between 2007 and 2013 (n = 143) were screened for post-RT thyroid stimulating hormone (TSH) levels (n = 77). The thyroid gland was contoured on each slice of the planning computed tomography scan when available (hypothyroid: n = 18; euthyroid > 2 years: n = 16), and dose-volume histograms based on physical dose and biologically equivalent dose (BED) were compared systematically to find the significant dose-volume thresholds that distinguish the patients who developed clinical hypothyroidism. Dosimetric and clinical variables were considered in univariate and multivariate analysis. Preirradiation prevalence of hypothyroidism was 8 of 143 (5.6%). After RT, 36 of 77 (47%) screened patients had abnormally high TSH, of which 22 of 36 (61%) had clinical hypothyroidism after 1.29 ± 0.99 years. The median follow-up durations were 3.3 years and 4.7 years for euthyroid and hypothyroid patients, respectively. Compared with the euthyroid cohort (n = 41), these hypothyroid patients displayed no significant difference in age, gender, primary tumor site, thyroid volume, hypertension, diabetes, or use of chemotherapy, surgery, or intensity-modulated radiation therapy (IMRT). They were more likely to have had stage 3 or 4 cancer than euthyroid patients (86.5% vs 73.2%, p = 0.01). The odds ratios of hypothyroidism for stage 3 + 4 cancers and V50Gy < 75% were 5.0 and 0.2, respectively (p < 0.05). Equivalent BED threshold of V75Gy 3  < 75% gave an odds ratio of 0.156 for developing hypothyroidism (p = 0.02). The prevalence of post-RT clinical hypothyroidism was relatively high for patients with H&N cancers and warrants routine surveillance, especially in those with higher stage malignancy. V50Gy < 75% may be a useful guideline to avoid hypothyroidism. We also show BED data which could be used for unconventionally fractionated schemes, and V75Gy 3  < 75% may be a useful guideline. Published by Elsevier Inc.

Comparison of Biological Responses in Rats Under Various Cigarette Smoke Exposure Conditions

PubMed Central

Tsuji, Hiroyuki; Fujimoto, Hitoshi; Matsuura, Daiki; Nishino, Tomoki; Lee, K Monica; Yoshimura, Hiroyuki

2013-01-01

A variety of exposure regimens of cigarette smoke have been used in animal models of lung diseases. In this study, we compared biological responses of smoke exposure in rats, using different smoke concentrations (wet total particulate matter [WTPM]), daily exposure durations, and total days of exposure. As a range-finding acute study, we first compared pulmonary responses between SD and F344 strains after a single nose-only exposure to mainstream cigarette smoke or LPS. Secondly, F344 rats were exposed to cigarette smoke for 2 or 13 weeks under the comparable daily exposure dose (WTPM concentration x daily exposure duration; according to Haber’s rule) but at a different WTPM concentration or daily exposure duration. Blood carboxylhemoglobin was increased linearly to the WTPM concentration, while urinary nicotine plus cotinine value was higher for the longer daily exposure than the corresponding shorter exposure groups. Gamma glutamyl transferase activity in bronchoalveolar lavage fluid (BALF) was increased dose dependently after 2 and 13 weeks of cigarette smoke exposure, while the neutrophil content in BALF was not increased notably. Smoke-exposed groups showed reduced body weight gain and increased relative lung and heart weights. While BALF parameters and the relative lung weights suggest pulmonary responses, histopathological examination showed epithelial lesions mainly in the upper respiratory organs (nose and larynx). Collectively, the results indicate that, under the employed study design, the equivalent daily exposure dose (exposure concentration x duration) induces equivalent pulmonary responses in rats. PMID:23914058

SU-E-T-567: Neutron Dose Equivalent Evaluation for Pencil Beam Scanning Proton Therapy with Apertures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geng, C; Nanjing University of Aeronautics and Astronautics, Nanjing; Schuemann, J

Purpose: To determine the neutron contamination from the aperture in pencil beam scanning during proton therapy. Methods: A Monte Carlo based proton therapy research platform TOPAS and the UF-series hybrid pediatric phantoms were used to perform this study. First, pencil beam scanning (PBS) treatment pediatric plans with average spot size of 10 mm at iso-center were created and optimized for three patients with and without apertures. Then, the plans were imported into TOPAS. A scripting method was developed to automatically replace the patient CT with a whole body phantom positioned according to the original plan iso-center. The neutron dose equivalentmore » was calculated using organ specific quality factors for two phantoms resembling a 4- and 14-years old patient. Results: The neutron dose equivalent generated by the apertures in PBS is 4–10% of the total neutron dose equivalent for organs near the target, while roughly 40% for organs far from the target. Compared to the neutron dose equivalent caused by PBS without aperture, the results show that the neutron dose equivalent with aperture is reduced in the organs near the target, and moderately increased for those organs located further from the target. This is due to the reduction of the proton dose around the edge of the CTV, which causes fewer neutrons generated in the patient. Conclusion: Clinically, for pediatric patients, one might consider adding an aperture to get a more conformal treatment plan if the spot size is too large. This work shows the somewhat surprising fact that adding an aperture for beam scanning for facilities with large spot sizes reduces instead of increases a potential neutron background in regions near target. Changran Geng is supported by the Chinese Scholarship Council (CSC) and the National Natural Science Foundation of China (Grant No. 11475087)« less

Peripheral photon and neutron doses from prostate cancer external beam irradiation.

PubMed

Bezak, Eva; Takam, Rundgham; Marcu, Loredana G

2015-12-01

Peripheral photon and neutron doses from external beam radiotherapy (EBRT) are associated with increased risk of carcinogenesis in the out-of-field organs; thus, dose estimations of secondary radiation are imperative. Peripheral photon and neutron doses from EBRT of prostate carcinoma were measured in Rando phantom. (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P glass-rod thermoluminescence dosemeters (TLDs) were inserted in slices of a Rando phantom followed by exposure to 80 Gy with 18-MV photon four-field 3D-CRT technique. The TLDs were calibrated using 6- and 18-MV X-ray beam. Neutron dose equivalents measured with CR-39 etch-track detectors were used to derive readout-to-neutron dose conversion factor for (6)LiF:Mg,Cu,P TLDs. Average neutron dose equivalents per 1 Gy of isocentre dose were 3.8±0.9 mSv Gy(-1) for thyroid and 7.0±5.4 mSv Gy(-1) for colon. For photons, the average dose equivalents per 1 Gy of isocentre dose were 0.2±0.1 mSv Gy(-1) for thyroid and 8.1±9.7 mSv Gy(-1) for colon. Paired (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P TLDs can be used to measure photon and neutron doses simultaneously. Organs in close proximity to target received larger doses from photons than those from neutrons whereas distally located organs received higher neutron versus photon dose. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Toxicity and Pharmacokinetic Profile for Single-Dose Injection of ABY-029: a Fluorescent Anti-EGFR Synthetic Affibody Molecule for Human Use.

PubMed

Samkoe, Kimberley S; Gunn, Jason R; Marra, Kayla; Hull, Sally M; Moodie, Karen L; Feldwisch, Joachim; Strong, Theresa V; Draney, Daniel R; Hoopes, P Jack; Roberts, David W; Paulsen, Keith; Pogue, Brian W

2017-08-01

ABY-029, a synthetic Affibody peptide, Z03115-Cys, labeled with a near-infrared fluorophore, IRDye® 800CW, targeting epidermal growth factor receptor (EGFR) has been produced under good manufacturing practices for a US Food and Drug Administration-approved first-in-use human study during surgical resection of glioma, as well as other tumors. Here, the pharmacology, phototoxicity, receptor activity, and biodistribution studies of ABY-029 were completed in rats, prior to the intended human use. Male and female Sprague Dawley rats were administered a single intravenous dose of varying concentrations (0, 245, 2449, and 24,490 μg/kg corresponding to 10×, 100×, and 1000× an equivalent human microdose level) of ABY-029 and observed for up to 14 days. Histopathological assessment of organs and tissues, clinical chemistry, and hematology were performed. In addition, pharmacokinetic clearance and biodistribution of ABY-029 were studied in subgroups of the animals. Phototoxicity and ABY-029 binding to human and rat EGFR were assessed in cell culture and on immobilized receptors, respectively. Histopathological assessment and hematological and clinical chemistry analysis demonstrated that single-dose ABY-029 produced no pathological evidence of toxicity at any dose level. No phototoxicity was observed in EGFR-positive and EGFR-negative glioma cell lines. Binding strength and pharmacokinetics of the anti-EGFR Affibody molecules were retained after labeling with the dye. Based on the successful safety profile of ABY-029, the 1000× human microdose 24.5 mg/kg was identified as the no observed adverse effect level following intravenous administration. Conserved binding strength and no observed light toxicity also demonstrated ABY-029 safety for human use.

Experience of micromultileaf collimator linear accelerator based single fraction stereotactic radiosurgery: Tumor dose inhomogeneity, conformity, and dose fall off

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Linda X.; Garg, Madhur; Lasala, Patrick

2011-03-15

Purpose: Sharp dose fall off outside a tumor is essential for high dose single fraction stereotactic radiosurgery (SRS) plans. This study explores the relationship among tumor dose inhomogeneity, conformity, and dose fall off in normal tissues for micromultileaf collimator (mMLC) linear accelerator (LINAC) based cranial SRS plans. Methods: Between January 2007 and July 2009, 65 patients with single cranial lesions were treated with LINAC-based SRS. Among them, tumors had maximum diameters {<=}20 mm: 31; between 20 and 30 mm: 21; and >30 mm: 13. All patients were treated with 6 MV photons on a Trilogy linear accelerator (Varian Medical Systems,more » Palo Alto, CA) with a tertiary m3 high-resolution mMLC (Brainlab, Feldkirchen, Germany), using either noncoplanar conformal fixed fields or dynamic conformal arcs. The authors also created retrospective study plans with identical beam arrangement as the treated plan but with different tumor dose inhomogeneity by varying the beam margins around the planning target volume (PTV). All retrospective study plans were normalized so that the minimum PTV dose was the prescription dose (PD). Isocenter dose, mean PTV dose, RTOG conformity index (CI), RTOG homogeneity index (HI), dose gradient index R{sub 50}-R{sub 100} (defined as the difference between equivalent sphere radius of 50% isodose volume and prescription isodose volume), and normal tissue volume (as a ratio to PTV volume) receiving 50% prescription dose (NTV{sub 50}) were calculated. Results: HI was inversely related to the beam margins around the PTV. CI had a ''V'' shaped relationship with HI, reaching a minimum when HI was approximately 1.3. Isocenter dose and mean PTV dose (as percentage of PD) increased linearly with HI. R{sub 50}-R{sub 100} and NTV{sub 50} initially declined with HI and then reached a plateau when HI was approximately 1.3. These trends also held when tumors were grouped according to their maximum diameters. The smallest tumor group (maximum diameters {<=}20 mm) had the most HI dependence for dose fall off. For treated plans, CI averaged 2.55{+-}0.79 with HI 1.23{+-}0.06; the average R{sub 50}-R{sub 100} was 0.41{+-}0.08, 0.55{+-}0.10, and 0.65{+-}0.09 cm, respectively, for tumors {<=}20 mm, between 20 and 30 mm, and >30 mm. Conclusions: Tumor dose inhomogeneity can be used as an important and convenient parameter to evaluate mMLC LINAC-based SRS plans. Sharp dose fall off in the normal tissue is achieved with sufficiently high tumor dose inhomogeneity. By adjusting beam margins, a homogeneity index of approximately 1.3 would provide best conformity for the authors' SRS system.« less

A comparison of traditional vs. Canadian tailored prophylaxis dosing of prophylactic factor infusions in children with haemophilia A and B in a single hemophilia treatment center.

PubMed

Dodd, C; Watts, R G

2012-07-01

Prophylactic infusion of clotting factor concentrates is a developing standard of care for individuals with haemophilia. The ideal schedule and techniques of prophylactic infusions remain incompletely defined. Our aim was to determine the optimal techniques and schedules for factor prophylaxis in paediatric patients. A retrospective electronic medical record review of all children treated with prophylactic factor infusions in a single Haemophilia Treatment Center was conducted. Comparison of traditional vs. Canadian dosing regimens and primary vs. secondary prophylaxis was made. Failure of prophylaxis was defined as the first serious bleed. A total of 58 children were identified for review. Five cases were excluded (four due to high titre inhibitors and one due to repeated non-compliance), thus there were 53 total cases: 46 with severe haemophilia, 2 with moderate haemophilia, 5 with mild haemophilia, 44 with haemophilia A and 9 with haemophilia B; 32 Traditional dosing and 21 Canadian dosing regimens. Patients on primary prophylaxis had a decreased failure rate (25%) compared to children treated with secondary prophylaxis (67%) regardless of technique of prophylaxis. When compared to a 'Traditional' factor prophylaxis schedule, the 'Canadian' tailored prophylaxis protocol was comparable with the exception of a decreased use of implanted venous devices in the 'Canadian' group. Ongoing bleeding (primarily joint bleeds) occurs with all prophylactic regimens. The lowest incidence of treatment failure was noted in children who began primary prophylaxis at a young age and before initial joint bleeds. Primary prophylaxis is superior to secondary prophylaxis regardless of dosing regimen. Traditional and Canadian dosing regimens were equivalent in outcome when measured over several years of follow-up. © 2012 Blackwell Publishing Ltd.

Tumor induction in mice after local irradiation with single doses of either carbon-ion beams or gamma rays.

PubMed

Ando, Koichi; Koike, Sachiko; Ohmachi, Yasushi; Ando, Yutaka; Kobashi, Gen

2014-12-01

To determine the dose-dependent relative biological effectiveness (RBE) for tumor prevalence in mice receiving single localized doses to their right leg of either carbon ions (15, 45 or 75 keV/μm) or 137Cs gamma rays. A total of 1647 female C3H mice were irradiated to their hind legs with a localized dose of either reference gamma rays or 15, 45 or 75 keV/μm carbon-ion beams. Irradiated mice were evaluated for tumors twice a month during their three-year life span, and the dimensions of any tumors found were measured with a caliper. The tumor induction frequency was calculated by Kaplan-Meier analysis. The incidence of tumors from 50 Gy of 45 keV/μm carbon ions was marginally higher than those from 50 Gy of gamma rays. However, 60 Gy of 15 keV/μm carbon ions induced significantly fewer tumors than did gamma rays. RBE values of 0.87 + 0.12, 1.29 + 0.08 or 2.06 + 0.39 for lifetime tumorigenesis were calculated for 15, 45 or 75 keV/μm carbon-ion beams, respectively. Fibrosarcoma predominated, with no Linear Energy Transfer (LET)-dependent differences in the tumor histology. Experiments measuring the late effect of leg skin shrinkage suggested that the carcinogenic damage of 15 keV/μm carbon ions would be less than that of gamma rays. We conclude that patients receiving radiation doses to their normal tissues would face less risk of secondary tumor induction by carbon ions of intermediate LET values compared to equivalent doses of photons.

Effect of treatment in fractionated schedules with the combination of x-irradiation and six cytotoxic drugs on the RIF-1 tumor and normal mouse skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lelieveld, P.; Scoles, M.A.; Brown, J.M.

1985-01-01

RIF-1 tumors, implanted syngeneically in the gastrocnemius muscles of the right hind legs of C3H/Km mice, were treated either with X ray alone, drug alone, or drug and X ray combined. The drugs tested were bleomycin, BCNU, cis-diamminedichloro platinum, adriamycin, cyclophosphamide, and actinomycin-D. All drugs were administered either in the maximum tolerated dose or a dose that causes minimal tumor growth delay. Both drugs and X rays were administered either as a single dose or in five daily fractions. In addition to the single modality controls, seven different schedules of combined modalities were tested. Tumors were measured periodically after treatmentmore » in order that the day at which each tumor reached 4 times its initial cross-sectional area, i.e., its size at the time of treatment, could be determined. The effect of treatment on tumors was based upon excess growth delay (GD), i.e., T400% (treated)-T400% (untreated control). Treatment effects for the same combined modality schedules were also determined for normal skin, using the early skin reaction as an endpoint. Dose effect factors (DEF) were computed for all combined modality schedules and were based upon calculated radiation dose equivalents. We also calculated supra-additivity ratios, SR/sub I/ and SR/sub II/, therapeutic gain factors and adjusted therapeutic gain factors. The only drugs to produce significant supra-additivity with X rays were cis-Pt and cyclo.« less

An open-label, single-dose, phase 1 study of the absorption, metabolism and excretion of quizartinib, a highly selective and potent FLT3 tyrosine kinase inhibitor, in healthy male subjects, for the treatment of acute myeloid leukemia.

PubMed

Sanga, Madhu; James, Joyce; Marini, Joseph; Gammon, Guy; Hale, Christine; Li, Jianke

2017-10-01

1. Quizartinib absorption, metabolism and excretion were characterized in six healthy men receiving a single oral dose of 60 mg (≈100 μCi) of [ 14 C]-quizartinib. Blood, plasma, urine and faeces were collected ≤336 h postdose. 2. Four hours postdose, maximum mean ± SD blood radioactivity concentrations were 296 ± 67.4 ng equivalents/g. A mean ± SD of 1.64 ± 0.482% and 76.3 ± 6.23% of the dose was recovered in urine and faeces, respectively, within 336 h postdose. 3. Radio-detector high-performance liquid chromatography (radio-HPLC) and liquid chromatography-mass spectrometry (LC-MS) showed two main radioactive peaks in plasma, unchanged quizartinib and mono-oxidative metabolite, AC886. Five additional metabolites in plasma were identified by LC-MS, but low levels prevented radio-HPLC detection. Although unchanged quizartinib was the main radioactive component in faeces (mean, 4.0% of administered dose), 15 metabolites representing a mean of 1.0-3.5% of administered dose were found. Quizartinib was predominantly metabolized by phase I biotransformations (oxidation, reduction, dealkylation, deamination, hydrolysis and combinations thereof). 4. This study indicated that quizartinib was rapidly and orally bioavailable, extensively metabolized, with AC886 as the major circulating metabolite, and predominantly eliminated in faeces. Quizartinib was well tolerated in the subjects.

Opioid needs of patients with advanced cancer and the morphine dose-limiting law in Egypt.

PubMed

Alsirafy, Samy A; El-Mesidi, Salah M; El-Sherief, Wesam A; Galal, Khaled M; Abou-Elela, Enas N; Aklan, Nahla A

2011-01-01

Morphine is the drug of choice for moderate to severe cancer pain management. The Egyptian Narcotics Control Law limits the amount of morphine prescribed in a single prescription to a maximum of 420 mg for tablets and 60 mg for ampoules. The usual practice in Egypt is to provide that limited amount of morphine on a weekly basis. The aim of this study is to estimate the extent to which Egyptian patients may be undertreated because of this law. We reviewed the medical records of advanced cancer patients referred to the first palliative care unit in Egypt over a seven-month period. Cancer pain was managed following the WHO guidelines. After modifying the internal institutional policy, patients received adequate amounts of the available opioids without any violations of the law. From 117 eligible advanced cancer patients, 58 (50%) patients required strong opioids, 32 (27%) required weak opioids, and 27 (23%) required no regular opioids. The mean last prescribed opioid dose for those who required strong opioids was 194 mg of oral morphine equivalent/24 h (± 180). For this group of patients, a single weekly prescription would supply enough oral morphine for only 26% of them. In the case of parenteral morphine, none of these patients would receive an adequate supply. In view of the current morphine dose-limiting law and practices in Egypt, the majority of patients suffering severe cancer pain would not have access to adequate morphine doses. That dose-limiting law and other restrictive regulations represent an obstacle to cancer pain control in Egypt and should be revised urgently.

30 CFR 62.101 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 85 dBA, or equivalently a dose of 50%, integrating all sound levels from 80 dBA to at least 130 dBA... Protection Level. A TWA8 of 105 dBA, or equivalently, a dose of 800% of that permitted by the standard, integrating all sound levels from 90 dBA to at least 140 dBA. Exchange rate. The amount of increase in sound...

30 CFR 62.101 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 85 dBA, or equivalently a dose of 50%, integrating all sound levels from 80 dBA to at least 130 dBA... Protection Level. A TWA8 of 105 dBA, or equivalently, a dose of 800% of that permitted by the standard, integrating all sound levels from 90 dBA to at least 140 dBA. Exchange rate. The amount of increase in sound...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

10 CFR 835.206 - Limits for the embryo/fetus.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Limits for the embryo/fetus. 835.206 Section 835.206... Exposure § 835.206 Limits for the embryo/fetus. (a) The equivalent dose limit for the embryo/fetus from the... provided in § 835.206(a) shall be avoided. (c) If the equivalent dose to the embryo/fetus is determined to...

Relevance of various animal models of human infections to establish therapeutic equivalence of a generic product of piperacillin/tazobactam.

PubMed

Agudelo, Maria; Rodriguez, Carlos A; Zuluaga, Andres F; Vesga, Omar

2015-02-01

After demonstrating with diverse intravenous antibacterials that pharmaceutical equivalence (PE) does not predict therapeutic equivalence, we tested a single generic product of piperacillin/tazobactam (TZP) in terms of PE, pharmacokinetics and in vitro/vivo pharmacodynamics against several pathogens in neutropenic mouse thigh, lung and brain infection models. A generic product was compared head-to-head against the innovator. PE was evaluated by microbiological assay. Single-dose serum pharmacokinetics were determined in infected mice, and the MIC/MBC were determined by broth microdilution. In vivo experiments were done in a blind fashion. Reproducibility was tested on different days using different infecting organisms and animal models. Neutropenic MPF mice were infected in the thighs with Staphylococcus aureus GRP-0057 or Pseudomonas aeruginosa PA01 and in the lungs or brain with Klebsiella pneumoniae ATCC 10031. Treatment started 2h (thigh and brain) or 14 h (lung) after infection and was administered every 3h over 24h (thigh and lung) or 48 h (brain). Both products exhibited the same MIC/MBC against each strain, yielded overlaid curves in the microbiological assay (P>0.21) and were bioequivalent (IC90 83-117% for AUC test/reference ratio). In vivo, the generic product and innovator were again undistinguishable in all models and against the different bacterial pathogens involved. The relevance of these neutropenic murine models of infection was established by demonstrating their accuracy to predict the biological response following simultaneous treatment with a generic product or the innovator of TZP. Therapeutic equivalence of the generic product was proved in every model and against different pathogens. Copyright © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

The reductive effect of an anti-pollinosis mask against internal exposure from radioactive materials dispersed from the Fukushima Daiichi Nuclear Disaster.

PubMed

Higaki, Shogo; Hirota, Masahiro

2013-02-01

The reductive effect of an anti-pollinosis mask against internal exposure from radioactive materials dispersed following the Fukushima Daiichi Nuclear Disaster was investigated. A single mask was worn continuously for 18 h from 15:00 JST on 15 March to 09:00 JST on 16 March 2011 at the Hongo campus of the University of Tokyo, Japan. An adult without a mask was exposed during this time to radiation of 6.1 μSv over ambient background in effective dose and 33 μSv in dose equivalent to the thyroid. Radionuclides were dispersed not only in their gaseous and particulate state but also as components that agglomerate to other aerosols and pollens. Wearing a mask for anti-pollinosis could reduce internal exposure from inhalation.

Monte Carlo simulation of the dose response of a novel 2D silicon diode array for use in hybrid MRI-LINAC systems.

PubMed

Gargett, Maegan; Oborn, Brad; Metcalfe, Peter; Rosenfeld, Anatoly

2015-02-01

MRI-guided radiation therapy systems (MRIgRT) are being developed to improve online imaging during treatment delivery. At present, the operation of single point dosimeters and an ionization chamber array have been characterized in such systems. This work investigates a novel 2D diode array, named "magic plate," for both single point calibration and 2D positional performance, the latter being a key element of modern radiotherapy techniques that will be delivered by these systems. geant4 Monte Carlo methods have been employed to study the dose response of a silicon diode array to 6 MV photon beams, in the presence of in-line and perpendicularly aligned uniform magnetic fields. The array consists of 121 silicon diodes (dimensions 1.5 × 1.5 × 0.38 mm(3)) embedded in kapton substrate with 1 cm pitch, spanning a 10 × 10 cm(2) area in total. A geometrically identical, water equivalent volume was simulated concurrently for comparison. The dose response of the silicon diode array was assessed for various photon beam field shapes and sizes, including an IMRT field, at 1 T. The dose response was further investigated at larger magnetic field strengths (1.5 and 3 T) for a 4 × 4 cm(2) photon field size. The magic plate diode array shows excellent correspondence (< ± 1%) to water dose in the in-line orientation, for all beam arrangements and magnetic field strengths investigated. The perpendicular orientation, however, exhibits a dose shift with respect to water at the high-dose-gradient beam edge of jaw-defined fields [maximum (4.3 ± 0.8)% over-response, maximum (1.8 ± 0.8)% under-response on opposing side for 1 T, uncertainty 1σ]. The trend is not evident in areas with in-field dose gradients typical of IMRT dose maps. A novel 121 pixel silicon diode array detector has been characterized by Monte Carlo simulation for its performance inside magnetic fields representative of current prototype and proposed MRI-linear accelerator systems. In the in-line orientation, the silicon dose is directly proportional to the water dose. In the perpendicular orientation, there is a shift in dose response relative to water in the highest dose gradient regions, at the edge of jaw-defined and single-segment MLC fields. The trend was not observed in-field for an IMRT beam. The array is expected to be a valuable tool in MRIgRT dosimetry.

Monte Carlo simulation of the dose response of a novel 2D silicon diode array for use in hybrid MRI–LINAC systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gargett, Maegan, E-mail: mg406@uowmail.edu.au; Rosenfeld, Anatoly; Oborn, Brad

2015-02-15

Purpose: MRI-guided radiation therapy systems (MRIgRT) are being developed to improve online imaging during treatment delivery. At present, the operation of single point dosimeters and an ionization chamber array have been characterized in such systems. This work investigates a novel 2D diode array, named “magic plate,” for both single point calibration and 2D positional performance, the latter being a key element of modern radiotherapy techniques that will be delivered by these systems. Methods: GEANT4 Monte Carlo methods have been employed to study the dose response of a silicon diode array to 6 MV photon beams, in the presence of in-linemore » and perpendicularly aligned uniform magnetic fields. The array consists of 121 silicon diodes (dimensions 1.5 × 1.5 × 0.38 mm{sup 3}) embedded in kapton substrate with 1 cm pitch, spanning a 10 × 10 cm{sup 2} area in total. A geometrically identical, water equivalent volume was simulated concurrently for comparison. The dose response of the silicon diode array was assessed for various photon beam field shapes and sizes, including an IMRT field, at 1 T. The dose response was further investigated at larger magnetic field strengths (1.5 and 3 T) for a 4 × 4 cm{sup 2} photon field size. Results: The magic plate diode array shows excellent correspondence (< ± 1%) to water dose in the in-line orientation, for all beam arrangements and magnetic field strengths investigated. The perpendicular orientation, however, exhibits a dose shift with respect to water at the high-dose-gradient beam edge of jaw-defined fields [maximum (4.3 ± 0.8)% over-response, maximum (1.8 ± 0.8)% under-response on opposing side for 1 T, uncertainty 1σ]. The trend is not evident in areas with in-field dose gradients typical of IMRT dose maps. Conclusions: A novel 121 pixel silicon diode array detector has been characterized by Monte Carlo simulation for its performance inside magnetic fields representative of current prototype and proposed MRI–linear accelerator systems. In the in-line orientation, the silicon dose is directly proportional to the water dose. In the perpendicular orientation, there is a shift in dose response relative to water in the highest dose gradient regions, at the edge of jaw-defined and single-segment MLC fields. The trend was not observed in-field for an IMRT beam. The array is expected to be a valuable tool in MRIgRT dosimetry.« less

The validation of tomotherapy dose calculations in low-density lung media

NASA Astrophysics Data System (ADS)

Chaudhari, Summer R.; Pechenaya, Olga L.; Goddu, S. Murty; Mutic, Sasa; Rangaraj, Dharanipathy; Bradley, Jeffrey D.; Low, Daniel

2009-04-01

The dose-calculation accuracy of the tomotherapy Hi-Art II® (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values <=1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.

The validation of tomotherapy dose calculations in low-density lung media.

PubMed

Chaudhari, Summer R; Pechenaya, Olga L; Goddu, S Murty; Mutic, Sasa; Rangaraj, Dharanipathy; Bradley, Jeffrey D; Low, Daniel

2009-04-21

The dose-calculation accuracy of the tomotherapy Hi-Art II(R) (Tomotherapy, Inc., Madison, WI) treatment planning system (TPS) in the presence of low-density lung media was investigated. In this evaluation, a custom-designed heterogeneous phantom mimicking the mediastinum geometry was used. Gammex LN300 and balsa wood were selected as two lung-equivalent materials with different densities. Film analysis and ionization chamber measurements were performed. Treatment plans for esophageal cancers were used in the evaluation. The agreement between the dose calculated by the TPS and the dose measured via ionization chambers was, in most cases, within 0.8%. Gamma analysis using 3% and 3 mm criteria for radiochromic film dosimetry showed that 98% and 95% of the measured dose distribution had passing gamma values < or =1 for LN300 and balsa wood, respectively. For a homogeneous water-equivalent phantom, 95% of the points passed the gamma test. It was found that for the interface between the low-density medium and water-equivalent medium, the TPS calculated the dose distribution within acceptable limits. The phantom developed for this work enabled detailed quality-assurance testing under realistic conditions with heterogeneous media.

Organ doses from radionuclides on the ground. Part I. Simple time dependences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacob, P.; Paretzke, H.G.; Rosenbaum, H.

1988-06-01

Organ dose equivalents of mathematical, anthropomorphical phantoms ADAM and EVA for photon exposures from plane sources on the ground have been calculated by Monte Carlo photon transport codes and tabulated in this article. The calculation takes into account the air-ground interface and a typical surface roughness, the energy and angular dependence of the photon fluence impinging on the phantom and the time dependence of the contributions from daughter nuclides. Results are up to 35% higher than data reported in the literature for important radionuclides. This manuscript deals with radionuclides, for which the time dependence of dose equivalent rates and dosemore » equivalents may be approximated by a simple exponential. A companion manuscript treats radionuclides with non-trivial time dependences.« less

JADA: a graphical user interface for comprehensive internal dose assessment in nuclear medicine.

PubMed

Grimes, Joshua; Uribe, Carlos; Celler, Anna

2013-07-01

The main objective of this work was to design a comprehensive dosimetry package that would keep all aspects of internal dose calculation within the framework of a single software environment and that would be applicable for a variety of dose calculation approaches. Our MATLAB-based graphical user interface (GUI) can be used for processing data obtained using pure planar, pure SPECT, or hybrid planar/SPECT imaging. Time-activity data for source regions are obtained using a set of tools that allow the user to reconstruct SPECT images, load images, coregister a series of planar images, and to perform two-dimensional and three-dimensional image segmentation. Curve fits are applied to the acquired time-activity data to construct time-activity curves, which are then integrated to obtain time-integrated activity coefficients. Subsequently, dose estimates are made using one of three methods. The organ level dose calculation subGUI calculates mean organ doses that are equivalent to dose assessment performed by OLINDA/EXM. Voxelized dose calculation options, which include the voxel S value approach and Monte Carlo simulation using the EGSnrc user code DOSXYZnrc, are available within the process 3D image data subGUI. The developed internal dosimetry software package provides an assortment of tools for every step in the dose calculation process, eliminating the need for manual data transfer between programs. This saves times and minimizes user errors, while offering a versatility that can be used to efficiently perform patient-specific internal dose calculations in a variety of clinical situations.

Estimates of internal-dose equivalent from inhalation and ingestion of selected radionuclides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunning, D.E.

1982-01-01

This report presents internal radiation dose conversion factors for radionuclides of interest in environmental assessments of nuclear fuel cycles. This volume provides an updated summary of estimates of committed dose equivalent for radionuclides considered in three previous Oak Ridge National Laboratory (ORNL) reports. Intakes by inhalation and ingestion are considered. The International Commission on Radiological Protection (ICRP) Task Group Lung Model has been used to simulate the deposition and retention of particulate matter in the respiratory tract. Results corresponding to activity median aerodynamic diameters (AMAD) of 0.3, 1.0, and 5.0 ..mu..m are given. The gastorintestinal (GI) tract has been representedmore » by a four-segment catenary model with exponential transfer of radioactivity from one segment to the next. Retention of radionuclides in systemic organs is characterized by linear combinations of decaying exponential functions, recommended in ICRP Publication 30. The first-year annual dose rate, maximum annual dose rate, and fifty-year dose commitment per microcurie intake of each radionuclide is given for selected target organs and the effective dose equivalent. These estimates include contributions from specified source organs plus the systemic activity residing in the rest of the body; cross irradiation due to penetrating radiations has been incorporated into these estimates. 15 references.« less

Radiation exposure for manned Mars surface missions

NASA Technical Reports Server (NTRS)

Simonsen, Lisa C.; Nealy, John E.; Townsend, Lawrence W.; Wilson, John W.

1990-01-01

The Langley cosmic ray transport code and the Langley nucleon transport code (BRYNTRN) are used to quantify the transport and attenuation of galactic cosmic rays (GCR) and solar proton flares through the Martian atmosphere. Surface doses are estimated using both a low density and a high density carbon dioxide model of the atmosphere which, in the vertical direction, provides a total of 16 g/sq cm and 22 g/sq cm of protection, respectively. At the Mars surface during the solar minimum cycle, a blood-forming organ (BFO) dose equivalent of 10.5 to 12 rem/yr due to galactic cosmic ray transport and attenuation is calculated. Estimates of the BFO dose equivalents which would have been incurred from the three large solar flare events of August 1972, November 1960, and February 1956 are also calculated at the surface. Results indicate surface BFO dose equivalents of approximately 2 to 5, 5 to 7, and 8 to 10 rem per event, respectively. Doses are also estimated at altitudes up to 12 km above the Martian surface where the atmosphere will provide less total protection.

Evaluation of the radiation dose in the thyroid gland using different protective collars in panoramic imaging.

PubMed

Hafezi, Ladan; Arianezhad, S Marjan; Hosseini Pooya, Seyed Mahdi

2018-04-25

The value for the use of thyroid shield is one of the issues in radiation protection of patients in dental panoramic imaging. The objective of this research is to investigate the attenuation characteristics of some models of thyroid shielding in dental panoramic examinations. The effects of five different types of lead and lead-free (Pb-equivalent) shields on dose reduction of thyroid gland were investigated using implanted Thermoluminescence Dosemeters (TLDs) in head-neck parts of a Rando phantom. The results show that frontal lead and Pb-equivalent shields can reduce the thyroid dose around 50% and 19%, respectively. It can be concluded that the effective shielding area is an important parameter in thyroid gland dose reduction. Lead frontal collars with large effective shielding areas (>~300 cm 2 but not necessarily very large) are appropriate for an optimized thyroid gland dose reduction particularly for the critical patients in dental panoramic imaging. Regardless of the shape and thickness, using the Pb-equivalent shields is not justifiable in dental panoramic imaging.

Dual-energy computed tomography of the head: a phantom study assessing axial dose distribution, eye lens dose, and image noise level

NASA Astrophysics Data System (ADS)

Matsubara, Kosuke; Kawashima, Hiroki; Hamaguchi, Takashi; Takata, Tadanori; Kobayashi, Masanao; Ichikawa, Katsuhiro; Koshida, Kichiro

2016-03-01

The aim of this study was to propose a calibration method for small dosimeters to measure absorbed doses during dual- source dual-energy computed tomography (DECT) and to compare the axial dose distribution, eye lens dose, and image noise level between DE and standard, single-energy (SE) head CT angiography. Three DE (100/Sn140 kVp 80/Sn140 kVp, and 140/80 kVp) and one SE (120 kVp) acquisitions were performed using a second-generation dual-source CT device and a female head phantom, with an equivalent volumetric CT dose index. The axial absorbed dose distribution at the orbital level and the absorbed doses for the eye lens were measured using radiophotoluminescent glass dosimeters. CT attenuation numbers were obtained in the DE composite images and the SE images of the phantom at the orbital level. The doses absorbed at the orbital level and in the eye lens were lower and standard deviations for the CT attenuation numbers were slightly higher in the DE acquisitions than those in the SE acquisition. The anterior surface dose was especially higher in the SE acquisition than that in the DE acquisitions. Thus, DE head CT angiography can be performed with a radiation dose lower than that required for a standard SE head CT angiography, with a slight increase in the image noise level. The 100/Sn140 kVp acquisition revealed the most balanced axial dose distribution. In addition, our proposed method was effective for calibrating small dosimeters to measure absorbed doses in DECT.

Impact of dose size in single fraction spatially fractionated (grid) radiotherapy for melanoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Hualin, E-mail: hualin.zhang@northwestern.edu, E-mail: hualinzhang@yahoo.com; Zhong, Hualiang; Barth, Rolf F.

2014-02-15

Purpose: To evaluate the impact of dose size in single fraction, spatially fractionated (grid) radiotherapy for selectively killing infiltrated melanoma cancer cells of different tumor sizes, using different radiobiological models. Methods: A Monte Carlo technique was employed to calculate the 3D dose distribution of a commercially available megavoltage grid collimator in a 6 MV beam. The linear-quadratic (LQ) and modified linear quadratic (MLQ) models were used separately to evaluate the therapeutic outcome of a series of single fraction regimens that employed grid therapy to treat both acute and late responding melanomas of varying sizes. The dose prescription point was atmore » the center of the tumor volume. Dose sizes ranging from 1 to 30 Gy at 100% dose line were modeled. Tumors were either touching the skin surface or having their centers at a depth of 3 cm. The equivalent uniform dose (EUD) to the melanoma cells and the therapeutic ratio (TR) were defined by comparing grid therapy with the traditional open debulking field. The clinical outcomes from recent reports were used to verify the authors’ model. Results: Dose profiles at different depths and 3D dose distributions in a series of 3D melanomas treated with grid therapy were obtained. The EUDs and TRs for all sizes of 3D tumors involved at different doses were derived through the LQ and MLQ models, and a practical equation was derived. The EUD was only one fifth of the prescribed dose. The TR was dependent on the prescribed dose and on the LQ parameters of both the interspersed cancer and normal tissue cells. The results from the LQ model were consistent with those of the MLQ model. At 20 Gy, the EUD and TR by the LQ model were 2.8% higher and 1% lower than by the MLQ, while at 10 Gy, the EUD and TR as defined by the LQ model were only 1.4% higher and 0.8% lower, respectively. The dose volume histograms of grid therapy for a 10 cm tumor showed different dosimetric characteristics from those of conventional radiotherapy. A significant portion of the tumor volume received a very large dose in grid therapy, which ensures significant tumor cell killing in these regions. Conversely, some areas received a relatively small dose, thereby sparing interspersed normal cells and increasing radiation tolerance. The radiobiology modeling results indicated that grid therapy could be useful for treating acutely responding melanomas infiltrating radiosensitive normal tissues. The theoretical model predictions were supported by the clinical outcomes. Conclusions: Grid therapy functions by selectively killing infiltrating tumor cells and concomitantly sparing interspersed normal cells. The TR depends on the radiosensitivity of the cell population, dose, tumor size, and location. Because the volumes of very high dose regions are small, the LQ model can be used safely to predict the clinical outcomes of grid therapy. When treating melanomas with a dose of 15 Gy or higher, single fraction grid therapy is clearly advantageous for sparing interspersed normal cells. The existence of a threshold fraction dose, which was found in the authors’ theoretical simulations, was confirmed by clinical observations.« less

High-energy neutron depth-dose distribution experiment.

PubMed

Ferenci, M S; Hertel, N E

2003-01-01

A unique set of high-energy neutron depth-dose benchmark experiments were performed at the Los Alamos Neutron Science Center/Weapons Neutron Research (LANSCE/WNR) complex. The experiments consisted of filtered neutron beams with energies up to 800 MeV impinging on a 30 x 30 x 30 cm3 liquid, tissue-equivalent phantom. The absorbed dose was measured in the phantom at various depths with tissue-equivalent ion chambers. This experiment is intended to serve as a benchmark experiment for the testing of high-energy radiation transport codes for the international radiation protection community.

Ionizing radiation measurements on LDEF: A0015 Free flyer biostack experiment

NASA Technical Reports Server (NTRS)

Benton, E. V.; Frank, A. L.; Benton, E. R.; Csige, I.; Frigo, L. A.

1995-01-01

This report covers the analysis of passive radiation detectors flown as part of the A0015 Free Flyer Biostack on LDEF (Long Duration Exposure Facility). LET (linear energy transfer) spectra and track density measurements were made with CR-39 and Polycarbonate plastic nuclear track detectors. Measurements of total absorbed dose were carried out using Thermoluminescent Detectors. Thermal and resonance neutron dose equivalents were measured with LiF/CR-39 detectors. High energy neutron and proton dose equivalents were measured with fission foil/CR-39 detectors.

Models of Hematopoietic Dynamics Following Burn for Use in Combined Injury Simulations

DTIC Science & Technology

2015-04-28

distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The effects of thermal injury were incorporated into previously developed models that...per kilogram (C kg–1) absorbed dose (rad) 1 × 10–2 joule per kilogram (J kg–1§) equivalent and effective dose (rem) 1 × 10–2 joule per kilogram (J...Gy = 1 J kg–1). **The special name for the SI unit of equivalent and effective dose is the sievert (Sv). (1 Sv = 1 J kg–1). Table of Contents Table

Monte carlo study of MOSFET packaging, optimised for improved energy response: single MOSFET filtration.

PubMed

Othman, M A R; Cutajar, D L; Hardcastle, N; Guatelli, S; Rosenfeld, A B

2010-09-01

Monte Carlo simulations of the energy response of a conventionally packaged single metal-oxide field effect transistors (MOSFET) detector were performed with the goal of improving MOSFET energy dependence for personal accident or military dosimetry. The MOSFET detector packaging was optimised. Two different 'drop-in' design packages for a single MOSFET detector were modelled and optimised using the GEANT4 Monte Carlo toolkit. Absorbed photon dose simulations of the MOSFET dosemeter placed in free-air response, corresponding to the absorbed doses at depths of 0.07 mm (D(w)(0.07)) and 10 mm (D(w)(10)) in a water equivalent phantom of size 30 x 30 x 30 cm(3) for photon energies of 0.015-2 MeV were performed. Energy dependence was reduced to within + or - 60 % for photon energies 0.06-2 MeV for both D(w)(0.07) and D(w)(10). Variations in the response for photon energies of 15-60 keV were 200 and 330 % for D(w)(0.07) and D(w)(10), respectively. The obtained energy dependence was reduced compared with that for conventionally packaged MOSFET detectors, which usually exhibit a 500-700 % over-response when used in free-air geometry.

A Monte Carlo study of the impact of the choice of rectum volume definition on estimates of equivalent uniform doses and the volume parameter

NASA Astrophysics Data System (ADS)

Kvinnsland, Yngve; Muren, Ludvig Paul; Dahl, Olav

2004-08-01

Calculations of normal tissue complication probability (NTCP) values for the rectum are difficult because it is a hollow, non-rigid, organ. Finding the true cumulative dose distribution for a number of treatment fractions requires a CT scan before each treatment fraction. This is labour intensive, and several surrogate distributions have therefore been suggested, such as dose wall histograms, dose surface histograms and histograms for the solid rectum, with and without margins. In this study, a Monte Carlo method is used to investigate the relationships between the cumulative dose distributions based on all treatment fractions and the above-mentioned histograms that are based on one CT scan only, in terms of equivalent uniform dose. Furthermore, the effect of a specific choice of histogram on estimates of the volume parameter of the probit NTCP model was investigated. It was found that the solid rectum and the rectum wall histograms (without margins) gave equivalent uniform doses with an expected value close to the values calculated from the cumulative dose distributions in the rectum wall. With the number of patients available in this study the standard deviations of the estimates of the volume parameter were large, and it was not possible to decide which volume gave the best estimates of the volume parameter, but there were distinct differences in the mean values of the values obtained.

Analytical-HZETRN Model for Rapid Assessment of Active Magnetic Radiation Shielding

NASA Technical Reports Server (NTRS)

Washburn, S. A.; Blattnig, S. R.; Singleterry, R. C.; Westover, S. C.

2014-01-01

The use of active radiation shielding designs has the potential to reduce the radiation exposure received by astronauts on deep-space missions at a significantly lower mass penalty than designs utilizing only passive shielding. Unfortunately, the determination of the radiation exposure inside these shielded environments often involves lengthy and computationally intensive Monte Carlo analysis. In order to evaluate the large trade space of design parameters associated with a magnetic radiation shield design, an analytical model was developed for the determination of flux inside a solenoid magnetic field due to the Galactic Cosmic Radiation (GCR) radiation environment. This analytical model was then coupled with NASA's radiation transport code, HZETRN, to account for the effects of passive/structural shielding mass. The resulting model can rapidly obtain results for a given configuration and can therefore be used to analyze an entire trade space of potential variables in less time than is required for even a single Monte Carlo run. Analyzing this trade space for a solenoid magnetic shield design indicates that active shield bending powers greater than 15 Tm and passive/structural shielding thicknesses greater than 40 g/cm2 have a limited impact on reducing dose equivalent values. Also, it is shown that higher magnetic field strengths are more effective than thicker magnetic fields at reducing dose equivalent.

Improved Bonner sphere neutron spectrometry measurements for the nuclear industry

NASA Astrophysics Data System (ADS)

Roberts, N. J.; Thomas, D. J.; Visser, T. P. P.

2017-11-01

A novel, two-stage approach has been developed for producing the a priori spectrum for Bonner sphere unfolding in a case where neutrons are produced by spontaneous fission and (α,n) reactions, e.g. in UF6. The code SOURCES 4C is first used to obtain the energy spectrum of the neutrons inside the material, which is then fed into a MCNP model of the entire geometry to derive the neutron spectrum at the location of the Bonner sphere. Using this as the a priori spectrum produces a much more detailed unfolded Bonner sphere spectrum retaining fine structure from the calculation that would not be present if a simple estimated spectrum had been used as the a priori spectrum. This is illustrated using a Bonner sphere measurement of the neutron energy spectrum produced by a 48Y cylinder of UF6. From the unfolded spectrum an estimate has been made of the neutron ambient dose equivalent, i.e. the quantity which a neutron survey instrument should measure. The difference in the ambient dose equivalent of the unfolded spectrum is over 10% when using the novel approach instead of using a simpler estimate consisting of a single high energy peak, 1/E continuum, and thermal peak.

A simple calculation method for determination of equivalent square field

PubMed Central

Shafiei, Seyed Ali; Hasanzadeh, Hadi; Shafiei, Seyed Ahmad

2012-01-01

Determination of the equivalent square fields for rectangular and shielded fields is of great importance in radiotherapy centers and treatment planning software. This is accomplished using standard tables and empirical formulas. The goal of this paper is to present a formula based on analysis of scatter reduction due to inverse square law to obtain equivalent field. Tables are published by different agencies such as ICRU (International Commission on Radiation Units and measurements), which are based on experimental data; but there exist mathematical formulas that yield the equivalent square field of an irregular rectangular field which are used extensively in computation techniques for dose determination. These processes lead to some complicated and time-consuming formulas for which the current study was designed. In this work, considering the portion of scattered radiation in absorbed dose at a point of measurement, a numerical formula was obtained based on which a simple formula was developed to calculate equivalent square field. Using polar coordinate and inverse square law will lead to a simple formula for calculation of equivalent field. The presented method is an analytical approach based on which one can estimate the equivalent square field of a rectangular field and may be used for a shielded field or an off-axis point. Besides, one can calculate equivalent field of rectangular field with the concept of decreased scatter radiation with inverse square law with a good approximation. This method may be useful in computing Percentage Depth Dose and Tissue-Phantom Ratio which are extensively used in treatment planning. PMID:22557801

Single-fraction flattening filter–free volumetric modulated arc therapy for lung cancer: Dosimetric results and comparison with flattened beams technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbiero, Sara; Specialty School in Medical Physics, University of Pisa, Pisa; Rink, Alexandra

2016-01-01

Purpose: To report on single-fraction stereotactic body radiotherapy (RT) (SBRT) with flattening filter (FF)–free (FFF) volumetric modulated arc therapy (VMAT) for lung cancer and to compare dosimetric results with VMAT with FF. Methods and materials: Overall, 25 patients were treated with 6-MV FFF VMAT (Varian TrueBeam STx LINAC) to a prescribed dose of 24 Gy in a single fraction. Treatment plans were recreated using FF VMAT. Dose-volume indices, monitor units (MU), and treatment times were compared between FFF and FF VMAT techniques. Results: Dose constraints to PTV, spinal cord, and lungs were reached in FFF and FF plans. In FFFmore » plans, average conformity index was 1.13 (95% CI: 1.07 to1.38). Maximum doses to spinal cord, heart, esophagus, and trachea were 2.9 Gy (95% CI: 0.4 to 6.7 Gy), 0.8 Gy (95% CI: 0 to 3.6 Gy), 3.3 Gy (95% CI: 0.02 to 13.9 Gy), and 1.5 Gy (95% CI: 0 to 4.9 Gy), respectively. Average V7 Gy, V7.4 Gy, and mean dose to the healthy lung were 126.5 cc (95% CI: 41.3 to 248.9 cc), 107.3 cc (95% CI: 18.7 to 232.8 cc), and 1.1 Gy (95% CI: 0.3 to 2.2 Gy), respectively. No statistically significant differences were found in dosimetric results and MU between FF and FFF treatments. Treatment time was reduced by an average factor of 2.31 (95% CI: 2.15 to 2.43) from FF treatments to FFF, and the difference was statistically significant. Conclusions: FFF VMAT for lung SBRT provides equivalent dosimetric results to the target and organs at risk as FF VMAT while significantly reducing treatment time.« less

Assessment of out-of-field absorbed dose and equivalent dose in proton fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clasie, Ben; Wroe, Andrew; Kooy, Hanne

2010-01-15

Purpose: In proton therapy, as in other forms of radiation therapy, scattered and secondary particles produce undesired dose outside the target volume that may increase the risk of radiation-induced secondary cancer and interact with electronic devices in the treatment room. The authors implement a Monte Carlo model of this dose deposited outside passively scattered fields and compare it to measurements, determine the out-of-field equivalent dose, and estimate the change in the dose if the same target volumes were treated with an active beam scanning technique. Methods: Measurements are done with a thimble ionization chamber and the Wellhofer MatriXX detector insidemore » a Lucite phantom with field configurations based on the treatment of prostate cancer and medulloblastoma. The authors use a GEANT4 Monte Carlo simulation, demonstrated to agree well with measurements inside the primary field, to simulate fields delivered in the measurements. The partial contributions to the dose are separated in the simulation by particle type and origin. Results: The agreement between experiment and simulation in the out-of-field absorbed dose is within 30% at 10-20 cm from the field edge and 90% of the data agrees within 2 standard deviations. In passive scattering, the neutron contribution to the total dose dominates in the region downstream of the Bragg peak (65%-80% due to internally produced neutrons) and inside the phantom at distances more than 10-15 cm from the field edge. The equivalent doses using 10 for the neutron weighting factor at the entrance to the phantom and at 20 cm from the field edge are 2.2 and 2.6 mSv/Gy for the prostate cancer and cranial medulloblastoma fields, respectively. The equivalent dose at 15-20 cm from the field edge decreases with depth in passive scattering and increases with depth in active scanning. Therefore, active scanning has smaller out-of-field equivalent dose by factors of 30-45 in the entrance region and this factor decreases with depth. Conclusions: The dose deposited immediately downstream of the primary field, in these cases, is dominated by internally produced neutrons; therefore, scattered and scanned fields may have similar risk of second cancer in this region. The authors confirm that there is a reduction in the out-of-field dose in active scanning but the effect decreases with depth. GEANT4 is suitable for simulating the dose deposited outside the primary field. The agreement with measurements is comparable to or better than the agreement reported for other implementations of Monte Carlo models. Depending on the position, the absorbed dose outside the primary field is dominated by contributions from primary protons that may or may not have scattered in the brass collimating devices. This is noteworthy as the quality factor of the low LET protons is well known and the relative dose risk in this region can thus be assessed accurately.« less

Estimation of Effective Doses for Radiation Cancer Risks on ISS, Lunar, and Mars Missions with Space Radiation Measurement

NASA Technical Reports Server (NTRS)

Kim, M.Y.; Cucinotta, F.A.

2005-01-01

Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. The Phantom Torso Experiment (PTE) of NASA s Operational Radiation Protection Program has provided the actual flight measurements of active and passive dosimeters which were placed throughout the phantom on STS-91 mission for 10 days and on ISS Increment 2 mission. For the PTE, the variation in organ doses, which is resulted by the absorption and the changes in radiation quality with tissue shielding, was considered by measuring doses at many tissue sites and at several critical body organs including brain, colon, heart, stomach, thyroid, and skins. These measurements have been compared with the organ dose calculations obtained from the transport models. Active TEPC measurements of lineal energy spectra at the surface of the PTE also provided the direct comparison of galactic cosmic ray (GCR) or trapped proton dose and dose equivalent. It is shown that orienting the phantom body as actual in ISS is needed for the direct comparison of the transport models to the ISS data. One of the most important observations for organ dose equivalent of effective dose estimates on ISS is the fractional contribution from trapped protons and GCR. We show that for most organs over 80% is from GCR. The improved estimation of effective doses for radiation cancer risks will be made with the resultant tissue weighting factors and the modified codes.

TCDD, FICZ, and Other High Affinity AhR Ligands Dose-Dependently Determine the Fate of CD4+ T Cell Differentiation.

PubMed

Ehrlich, Allison K; Pennington, Jamie M; Bisson, William H; Kolluri, Siva K; Kerkvliet, Nancy I

2018-02-01

FICZ and TCDD, two high-affinity AhR ligands, are reported to have opposite effects on T cell differentiation with TCDD inducing regulatory T cells and FICZ inducing Th17 cells. This dichotomy has been attributed to ligand-intrinsic differences in AhR activation, although differences in sensitivity to metabolism complicate the issue. TCDD is resistant to AhR-induced metabolism and produces sustained AhR activation following a single dose in the μg/kg range, whereas FICZ is rapidly metabolized and AhR activation is transient. Nonetheless, prior studies comparing FICZ with TCDD have generally used the same 10-50 μg/kg dose range, and thus the two ligands would not equivalently activate AhR. We hypothesized that high-affinity AhR ligands can promote CD4+ T cell differentiation into both Th17 cells and Tregs, with fate depending on the extent and duration of AhR activation. We compared the immunosuppressive effects of TCDD and FICZ, along with two other rapidly metabolized ligands (ITE and 11-Cl-BBQ) in an acute alloresponse mouse model. The dose and timing of administration of each ligand was optimized for TCDD-equivalent Cyp1a1 induction. When optimized, all of the ligands suppressed the alloresponse in conjunction with the induction of Foxp3- Tr1 cells on day 2 and the expansion of natural Foxp3+ Tregs on day 10. In contrast, a low dose of FICZ induced transient expression of Cyp1a1 and did not induce Tregs or suppress the alloresponse but enhanced IL-17 production. Interestingly, low doses of the other ligands, including TCDD, also increased IL-17 production on day 10. These findings support the conclusion that the dose and the duration of AhR activation by high-affinity AhR ligands are the primary factors driving the fate of T cell differentiation. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Space radiation dosimetry in low-Earth orbit and beyond.

PubMed

Benton, E R; Benton, E V

2001-09-01

Space radiation dosimetry presents one of the greatest challenges in the discipline of radiation protection. This is a result of both the highly complex nature of the radiation fields encountered in low-Earth orbit (LEO) and interplanetary space and of the constraints imposed by spaceflight on instrument design. This paper reviews the sources and composition of the space radiation environment in LEO as well as beyond the Earth's magnetosphere. A review of much of the dosimetric data that have been gathered over the last four decades of human space flight is presented. The different factors affecting the radiation exposures of astronauts and cosmonauts aboard the International Space Station (ISS) are emphasized. Measurements made aboard the Mir Orbital Station have highlighted the importance of both secondary particle production within the structure of spacecraft and the effect of shielding on both crew dose and dose equivalent. Roughly half the dose on ISS is expected to come from trapped protons and half from galactic cosmic rays (GCRs). The dearth of neutron measurements aboard LEO spacecraft and the difficulty inherent in making such measurements have led to large uncertainties in estimates of the neutron contribution to total dose equivalent. Except for a limited number of measurements made aboard the Apollo lunar missions, no crew dosimetry has been conducted beyond the Earth's magnetosphere. At the present time we are forced to rely on model-based estimates of crew dose and dose equivalent when planning for interplanetary missions, such as a mission to Mars. While space crews in LEO are unlikely to exceed the exposure limits recommended by such groups as the NCRP, dose equivalents of the same order as the recommended limits are likely over the course of a human mission to Mars. c2001 Elsevier Science B.V. All rights reserved.

Measurement and simulation of lineal energy distribution at the CERN high energy facility with a tissue equivalent proportional counter.

PubMed

Rollet, S; Autischer, M; Beck, P; Latocha, M

2007-01-01

The response of a tissue equivalent proportional counter (TEPC) in a mixed radiation field with a neutron energy distribution similar to the radiation field at commercial flight altitudes has been studied. The measurements have been done at the CERN-EU High-Energy Reference Field (CERF) facility where a well-characterised radiation field is available for intercomparison. The TEPC instrument used by the ARC Seibersdorf Research is filled with pure propane gas at low pressure and can be used to determine the lineal energy distribution of the energy deposition in a mass of gas equivalent to a 2 microm diameter volume of unit density tissue, of similar size to the nuclei of biological cells. The linearity of the detector response was checked both in term of dose and dose rate. The effect of dead-time has been corrected. The influence of the detector exposure location and orientation in the radiation field on the dose distribution was also studied as a function of the total dose. The microdosimetric distribution of the absorbed dose as a function of the lineal energy has been obtained and compared with the same distribution simulated with the FLUKA Monte Carlo transport code. The dose equivalent was calculated by folding this distribution with the quality factor as a function of linear energy transfer. The comparison between the measured and simulated distributions show that they are in good agreement. As a result of this study the detector is well characterised, thanks also to the numerical simulations the instrument response is well understood, and it's currently being used onboard the aircrafts to evaluate the dose to aircraft crew caused by cosmic radiation.

Determination of naturally radioactive elements in chalk sticks by means of gamma spectroscopy

NASA Astrophysics Data System (ADS)

Abd El-Wahab, Magda; Morsy, Zeinab; El-Faramawy, Nabil

2010-04-01

The radiation hazards due to ingestion of chalkboard dust were investigated. Sixteen samples from three different origin fabricates were used. The estimation of radiation hazard indices were based on the evaluation of the concentration activities of the natural radionuclides 238U, 232Th and 40K. The radium equivalent activity, external hazard index, internal hazard index and the annual dose equivalent associated with the radionuclides were calculated and compared with international recommended values to assess the radiation hazard. The values of internal and external radiation hazard indices were found to be less than unity. The annual effective dose rate obtained, E eff, and the annual gonadal dose equivalent (AGDE) are found to be less than the limit of the doses recommended by the International Commission on Radiological Protection for the general public. The analytical results show that besides the main calcium content, some toxic elements, S, Mo and Pb and Ni and Pb, in the Egyptian and imported chalk stocks, respectively, existed.

Determination of naturally radioactive elements in chalk sticks by means of gamma spectroscopy

NASA Astrophysics Data System (ADS)

El-Wahab, Magda Abd; Morsy, Zeinab; El-Faramawy, Nabil

The radiation hazards due to ingestion of chalkboard dust were investigated. Sixteen samples from three different origin fabricates were used. The estimation of radiation hazard indices were based on the evaluation of the concentration activities of the natural radionuclides 238U, 232Th and 40K. The radium equivalent activity, external hazard index, internal hazard index and the annual dose equivalent associated with the radionuclides were calculated and compared with international recommended values to assess the radiation hazard. The values of internal and external radiation hazard indices were found to be less than unity. The annual effective dose rate obtained, Eeff, and the annual gonadal dose equivalent (AGDE) are found to be less than the limit of the doses recommended by the International Commission on Radiological Protection for the general public. The analytical results show that besides the main calcium content, some toxic elements, S, Mo and Pb and Ni and Pb, in the Egyptian and imported chalk stocks, respectively, existed.

Observations on personnel dosimetry for radiotherapy personnel operating high-energy LINACs.

PubMed

Glasgow, G P; Eichling, J; Yoder, R C

1986-06-01

A series of measurements were conducted to determine the cause of a sudden increase in personnel radiation exposures. One objective of the measurements was to determine if the increases were related to changing from film dosimeters exchanged monthly to TLD-100 dosimeters exchanged quarterly. While small increases were observed in the dose equivalents of most employees, the dose equivalents of personnel operating medical electron linear accelerators with energies greater than 20 MV doubled coincidentally with the change in the personnel dosimeter program. The measurements indicated a small thermal neutron radiation component around the accelerators operated by these personnel. This component caused the doses measured with the TLD-100 dosimeters to be overstated. Therefore, the increase in these personnel dose equivalents was not due to changes in work habits or radiation environments. Either film or TLD-700 dosimeters would be suitable for personnel monitoring around high-energy linear accelerators. The final choice would depend on economics and personal preference.

Water-equivalent fiber radiation dosimeter with two scintillating materials

PubMed Central

Qin, Zhuang; Hu, Yaosheng; Ma, Yu; Lin, Wei; Luo, Xianping; Zhao, Wenhui; Sun, Weimin; Zhang, Daxin; Chen, Ziyin; Wang, Boran; Lewis, Elfed

2016-01-01

An inorganic scintillating material plastic optical fiber (POF) dosimeter for measuring ionizing radiation during radiotherapy applications is reported. It is necessary that an ideal dosimeter exhibits many desirable qualities, including water equivalence, energy independence, reproducibility, dose linearity. There has been much recent research concerning inorganic dosimeters. However, little reference has been made to date of the depth-dose characteristics of dosimeter materials. In the case of inorganic scintillating materials, they are predominantly non water-equivalent, with their effective atomic weight (Zeff) being typically much greater than that of water. This has been a barrier in preventing inorganic scintillating material dosimeter from being used in actual clinical applications. In this paper, we propose a parallel-paired fiber light guide structure to solve this problem. Two different inorganic scintillating materials are embedded separately in the parallel-paired fiber. It is shown that the information of water depth and absorbed dose at the point of measurement can be extracted by utilizing their different depth-dose properties. PMID:28018715

Evaluation of LiF:Mg,Ti (TLD-100) for Intraoperative Electron Radiation Therapy Quality Assurance

PubMed Central

Liuzzi, Raffaele; Savino, Federica; D’Avino, Vittoria; Pugliese, Mariagabriella; Cella, Laura

2015-01-01

Background Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2–12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters. Methods LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0–10 Gy in step of 2Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy. Results The TLD-100 dose-response curves were obtained. In the dose range of 0–10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05). Conclusions This study demonstrates that the TLD dose response, for doses ≤10Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided. PMID:26427065

Evaluation of LiF:Mg,Ti (TLD-100) for Intraoperative Electron Radiation Therapy Quality Assurance.

PubMed

Liuzzi, Raffaele; Savino, Federica; D'Avino, Vittoria; Pugliese, Mariagabriella; Cella, Laura

2015-01-01

Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2-12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters. LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0-10 Gy in step of 2 Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy. The TLD-100 dose-response curves were obtained. In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05). This study demonstrates that the TLD dose response, for doses ≤10 Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided.

A U.S. Multicenter Study of Recorded Occupational Radiation Badge Doses in Nuclear Medicine.

PubMed

Villoing, Daphnée; Yoder, R Craig; Passmore, Christopher; Bernier, Marie-Odile; Kitahara, Cari M

2018-05-01

Purpose To summarize occupational badge doses recorded for a sample of U.S. nuclear medicine technologists. Materials and Methods Nine large U.S. medical institutions identified 208 former and current nuclear medicine technologists certified after 1979 and linked these individuals to historic badge dose records maintained by a commercial dosimetry company (Landauer), yielding a total of 2618 annual dose records. The distributions of annual and cumulative occupational doses were described by using summary statistics. Results Between 1992 and 2015, the median annual personal dose equivalent per nuclear medicine technologist was 2.18 mSv (interquartile range [IQR], 1.25-3.47 mSv; mean, 2.69 mSv). Median annual personal dose equivalents remained relatively constant over this period (range, 1.40-3.30 mSv), while maximum values generally increased over time (from 8.00 mSv in 1992 to 13.9 mSv in 2015). The median cumulative personal dose equivalent was 32.9 mSv (IQR, 18.1-65.5 mSv; mean, 51.4 mSv) for 45 technologists who had complete information and remained employed through 2015. Conclusion Occupational radiation doses were well below the established occupational limits and were consistent with those observed for nuclear medicine technologists worldwide and were greater than those observed for nuclear and general medical workers in the United States These results should be informative for radiation monitoring and safety efforts in nuclear medicine departments. © RSNA, 2018 Online supplemental material is available for this article.

Evaluation of Gafchromic EBT-XD film, with comparison to EBT3 film, and application in high dose radiotherapy verification.

PubMed

Palmer, Antony L; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H

2015-11-21

There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison.

Evaluation of Gafchromic EBT-XD film, with comparison to EBT3 film, and application in high dose radiotherapy verification

NASA Astrophysics Data System (ADS)

Palmer, Antony L.; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H.

2015-11-01

There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison.

Safety and efficacy of stereotactic radiosurgery for tumors of the spine.

PubMed

Benzil, Deborah L; Saboori, Mehran; Mogilner, Alon Y; Rocchio, Ronald; Moorthy, Chitti R

2004-11-01

The extension of stereotactic radiosurgery treatment of tumors of the spine has the potential to benefit many patients. As in the early days of cranial stereotactic radiosurgery, however, dose-related efficacy and toxicity are not well understood. The authors report their initial experience with stereotactic radiosurgery of the spine with attention to dose, efficacy, and toxicity. All patients who underwent stereotactic radiosurgery of the spine were treated using the Novalis unit at Westchester Medical Center between December 2001 and January 2004 are included in a database consisting of demographics on disease, dose, outcome, and complications. A total of 31 patients (12 men, 19 women; mean age 61 years, median age 63 years) received treatment for 35 tumors. Tumor types included 26 metastases (12 lung, nine breast, five other) and nine primary tumors (four intradural, five extradural). Thoracic tumors were most common (17 metastases and four primary) followed by lumbar tumors (four metastases and four primary). Lesions were treated to the 85 to 90% isodose line with spinal cord doses being less than 50%. The dose per fraction and total dose were selected on the basis of previous treatment (particularly radiation exposure), size of lesion, and proximity to critical structures. Rapid and significant pain relief was achieved after stereotactic radiosurgery in 32 of 34 treated tumors. In patients treated for metastases, pain was relieved within 72 hours and remained reduced 3 months later. Pain relief was achieved with a single dose as low as 500 cGy. Spinal cord isodoses were less than 50% in all patients except those with intradural tumors (mean single dose to spinal cord 268 cGy and mean total dose to spinal cord 689 cGy). Two patients experienced transient radiculitis (both with a biological equivalent dose (BED) > 60 Gy). One patient who suffered multiple recurrences of a conus ependymoma had permanent neurological deterioration after initial improvement. Pathological evaluation of this lesion at surgery revealed radiation necrosis with some residual/recurrent tumor. No patient experienced other organ toxicity. Stereotactic radiosurgery of the spine is safe at the doses used and provides effective pain relief. In this study, BEDs greater than 60 Gy were associated with an increased risk of radiculitis.

Trends of population radiation adsorbed dose from diagnostic nuclear medicine procedures in Iran: 1985-1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammadi, H.; Tabeie, F.; Saghari, M.

1995-04-01

In view of the rapid expansion of diagnostic nuclear medicine procedures in Iran, this study was undertaken to examine trends of nuclear medicine practice in the country and to determine the mean effective dose equivalent per patient and per capita. Comprehensive national data covering 93% of all nuclear medicine centers in 1985-1989 were obtained. The total number of nuclear medicine examinations inc teased by 42% during these years. The relative frequency of thyroid investigations was 84% followed by liver/spleen and bone procedures (7% and 6%, respectively). {sup 99m}Tc was the radionuclide of choice for 86% of investigation while {sup 131}Imore » alone accounted for 59% of collective effective dose equivalent. The annual average number of nuclear medicine procedures per 1,000 people was 1.9. For the thyroid, the highest number (48%) of patients investigated was in the 15-29 y age group and the lowest (3%) was in the >64 y age group. The male to female ratio of thyroid and cardiac patient was 0.18 and 3.64, respectively. The numbers of males and females studied for the remaining eight procedures were less frequent and about the same. The mean effective dose equivalent per patient and per capita was about 4.3 mSv and 8 {mu}Sv, respectively. {sup 131}I was responsible for most of collective effective dose equivalent produced by nuclear medicine. Therefore, future efforts should be concentrated on dose reduction for diagnostic {sup 131}I tests.« less

TU-F-CAMPUS-T-02: Risk Assessment of Scattered Neutrons for a Fetus From Proton Therapy of a Brain Tumor During Pregnancy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geng, C; Nanjing University of Aeronautics and Astronautics, Nanjing; Moteabbed, M

Purpose: To determine the scattered neutron dose and the resulting risk for a fetus from proton therapy for brain tumors during pregnancy. Methods: Using the Monte Carlo platform TOPAS, the ICRP reference parameters based anthropomorphic pregnancy phantoms for three stages (3-, 6-, 9-month) were applied to evaluate the scattered neutron dose and dose equivalent. To calculate the dose equivalent, organ specific linear energy transfer (LET) based quality factor was used. Treatment plans from both passive scattering (PS) and pencil beam scanning (PBS) methods were considered in this study. Results: For pencil beam scanning, the neutron dose equivalent in the softmore » tissue of the fetus increases from 1.53x10−{sup 3} to 2.84x10−{sup 3} mSv per treatment Gy with increasing stage of gestation. This is due to scattered neutrons from the patient as the main contaminant source in PBS and a decrease in distance between the soft tissue of the fetus and GTV with increasing stage of gestation. For passive scattering, neutron dose equivalent to the soft tissue of the fetus shows a decrease from 0.17 to 0.13 mSv per treatment Gy in different stages, while the dose to the brain shows little difference around 0.18 mSv per treatment Gy because scattered neutrons from the treatment head contribute predominantly in passive scattering. Conclusion: The results show that the neutron dose to the fetus assuming a prescribed dose of 52.2 Gy is negligible for PBS, and is comparable to the scattered dose (0–10 mSv) from a head and neck CT scan for PS. It can be concluded that the dose to fetus is far lower than the thresholds of malformation, SMR and lethal death. The excess relative risk of childhood cancer induction would be increased by 0.48 and 0.103 using the Oxford Survey of Childhood Cancers and Japanese atomic model, respectively. Changran Geng is supported by the Chinese Scholarship Council (CSC) and the National Natural Science Foundation of China (Grant No. 11475087)« less

Dose measurement in heterogeneous phantoms with an extrapolation chamber

NASA Astrophysics Data System (ADS)

Deblois, Francois

A hybrid phantom-embedded extrapolation chamber (PEEC) made of Solid Water(TM) and bone-equivalent material was used for determining absolute dose in a bone-equivalent phantom irradiated with clinical radiation beams (cobalt-60 gamma rays; 6 and 18 MV x-rays; and 9 and 15 MeV electrons). The dose was determined with the Spencer-Attix cavity theory, using ionization gradient measurements and an indirect determination of the chamber air-mass through measurements of chamber capacitance. The air gaps used were between 2 and 3 mm and the sensitive air volume of the extrapolation chamber was remotely controlled through the motion of the motorized piston with a precision of +/-0.0025 mm. The collected charge was corrected for ionic recombination and diffusion in the chamber air volume following the standard two-voltage technique. Due to the hybrid chamber design, correction factors accounting for scatter deficit and electrode composition were determined and applied in the dose equation to obtain dose data for the equivalent homogeneous bone phantom. Correction factors for graphite electrodes were calculated with Monte Carlo techniques and the calculated results were verified through relative air cavity dose measurements for three different polarizing electrode materials: graphite, steel, and brass in conjunction with a graphite collecting electrode. Scatter deficit, due mainly to loss of lateral scatter in the hybrid chamber, reduces the dose to the air cavity in the hybrid PEEC in comparison with full bone PEEC from 0.7 to ˜2% depending on beam quality and energy. In megavoltage photon and electron beams, graphite electrodes do not affect the dose measurement in the Solid Water(TM) PEEC but decrease the cavity dose by up to 5% in the bone-equivalent PEEC even for very thin graphite electrodes (<0.0025 cm). The collecting electrode material in comparison with the polarizing electrode material has a larger effect on the electrode correction factor; the thickness of thin electrodes, on the other hand, has a negligible effect on dose determination. The uncalibrated hybrid PEEC is an accurate and absolute device for measuring the dose directly in bone material in conjunction with appropriate correction factors determined with Monte Carlo techniques.

Simulated Response of a Tissue-equivalent Proportional Counter on the Surface of Mars.

PubMed

Northum, Jeremy D; Guetersloh, Stephen B; Braby, Leslie A; Ford, John R

2015-10-01

Uncertainties persist regarding the assessment of the carcinogenic risk associated with galactic cosmic ray (GCR) exposure during a mission to Mars. The GCR spectrum peaks in the range of 300(-1) MeV n to 700 MeV n(-1) and is comprised of elemental ions from H to Ni. While Fe ions represent only 0.03% of the GCR spectrum in terms of particle abundance, they are responsible for nearly 30% of the dose equivalent in free space. Because of this, radiation biology studies focusing on understanding the biological effects of GCR exposure generally use Fe ions. Acting as a thin shield, the Martian atmosphere alters the GCR spectrum in a manner that significantly reduces the importance of Fe ions. Additionally, albedo particles emanating from the regolith complicate the radiation environment. The present study uses the Monte Carlo code FLUKA to simulate the response of a tissue-equivalent proportional counter on the surface of Mars to produce dosimetry quantities and microdosimetry distributions. The dose equivalent rate on the surface of Mars was found to be 0.18 Sv y(-1) with an average quality factor of 2.9 and a dose mean lineal energy of 18.4 keV μm(-1). Additionally, albedo neutrons were found to account for 25% of the dose equivalent. It is anticipated that these data will provide relevant starting points for use in future risk assessment and mission planning studies.

Corrigendum to "Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit".

PubMed

El-Jaby, Samy

2016-06-01

A recent paper published in Life Sciences in Space Research (El-Jaby and Richardson, 2015) presented estimates of the secondary neutron ambient and effective dose equivalent rates, in air, from surface altitudes up to suborbital altitudes and low Earth orbit. These estimates were based on MCNPX (LANL, 2011) (Monte Carlo N-Particle eXtended) radiation transport simulations of galactic cosmic radiation passing through Earth's atmosphere. During a recent review of the input decks used for these simulations, a systematic error was discovered that is addressed here. After reassessment, the neutron ambient and effective dose equivalent rates estimated are found to be 10 to 15% different, though, the essence of the conclusions drawn remains unchanged. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Radiation dose equivalent to stowaways in vehicles.

PubMed

Khan, Siraj M; Nicholas, Paul E; Terpilak, Michael S

2004-05-01

The U.S. Bureau of Customs and Border Protection has deployed a large number of non-intrusive inspection (NII) systems at land border crossings and seaports throughout the United States to inspect cars, trucks, and sea containers. These NII systems use x rays and gamma rays for the detection of contraband. Unfortunately, undocumented aliens infrequently stow away in these same conveyances to illegally enter the United States. It is extremely important that the radiation dose equivalent imparted to these stowaways be within acceptable limits. This paper discusses the issues involved and describes a protocol the U.S. Bureau of Customs and Border Protection has used in a study to measure and document these levels. The results of this study show that the radiation dose equivalent to the stowaways from the deployed NII systems is negligibly small and does not pose a health hazard.

Radiation exposure of the radiologist's eye lens during CT-guided interventions.

PubMed

Heusch, Philipp; Kröpil, Patric; Buchbender, Christian; Aissa, Joel; Lanzman, Rotem S; Heusner, Till A; Ewen, Klaus; Antoch, Gerald; Fürst, Günther

2014-02-01

In the past decade the number of computed tomography (CT)-guided procedures performed by interventional radiologists have increased, leading to a significantly higher radiation exposure of the interventionalist's eye lens. Because of growing concern that there is a stochastic effect for the development of lens opacification, eye lens dose reduction for operators and patients should be of maximal interest. To determine the interventionalist's equivalent eye lens dose during CT-guided interventions and to relate the results to the maximum of the recommended equivalent dose limit. During 89 CT-guided interventions (e.g. biopsies, drainage procedures, etc.) measurements of eye lens' radiation doses were obtained from a dedicated dosimeter system for scattered radiation. The sensor of the personal dosimeter system was clipped onto the side of the lead glasses which was located nearest to the CT gantry. After the procedure, radiation dose (µSv), dose rate (µSv/min) and the total exposure time (s) were recorded. For all 89 interventions, the median total exposure lens dose was 3.3 µSv (range, 0.03-218.9 µSv) for a median exposure time of 26.2 s (range, 1.1-94.0 s). The median dose rate was 13.9 µSv/min (range, 1.1-335.5 µSv/min). Estimating 50-200 CT-guided interventions per year performed by one interventionalist, the median dose of the eye lens of the interventional radiologist does not exceed the maximum of the ICRP-recommended equivalent eye lens dose limit of 20 mSv per year.

Characterization of the radiation environment at the UNLV accelerator facility during operation of the Varian M6 linac

NASA Astrophysics Data System (ADS)

Hodges, M.; Barzilov, A.; Chen, Y.; Lowe, D.

2016-10-01

The bremsstrahlung photon flux from the UNLV particle accelerator (Varian M6 model) was determined using MCNP5 code for 3 MeV and 6 MeV incident electrons. Human biological equivalent dose rates due to accelerator operation were evaluated using the photon flux with the flux-to-dose conversion factors. Dose rates were computed for the accelerator facility for M6 linac use under different operating conditions. The results showed that the use of collimators and linac internal shielding significantly reduced the dose rates throughout the facility. It was shown that the walls of the facility, in addition to the earthen berm enveloping the building, provide equivalent shielding to reduce dose rates outside to below the 2 mrem/h limit.

Distribution and elimination of [14C] sarafloxacin hydrochloride from tissues of juvenile channel catfish (Ictalurus punctatus)

USGS Publications Warehouse

Gingerich, W.H.; Meinertz, J.R.; Dawson, V.K.; Gofus, J.E.; Delaney, L.J.; Bunnell, P.R.

1995-01-01

The distribution and loss of radioactivity from tissues were determined in 60 juvenile channel catfish (Ictalurus punctatus) following oral dosing with the candidate fish therapeutant Sarafin® ([14C] sarafloxacin hydrochloride) at 10 mg/kg for 5 consecutive days. Twelve groups of 5 fish each were sampled at selected times ranging from 3 to 240 h after the last dose was administered, The concentration and content of sarafloxacin-equivalent activity was determined in liver, gallbladder, kidney, skin, and skinless fillet by sample oxidation and liquid scintillation counting; content of sarafloxacin-equivalent activity was determined in stomach and anterior and posterior intestines, Skinless fillet tissues were also analyzed for sarafloxacin and for potential metabolites by gradient-elution high-performance liquid chromatography (HPLC) with in-line radiometric and fluorescence detection, Loss of radioactivity from the whole body conformed to a bimodal elimination pattern with a rapid initial phase (t1/2=11 h) and a slower secondary phase (t1/2=222 h). Tissue and contents of the gastrointestinal tract (i.e. stomach and anterior and posterior intestines) were a principal depot of activity during the first four sample times (3, 6, 12, and 24 h); the combined head, skeleton, and fins (i.e. residual carcass) were the principal depot of activity in samples taken after 24 h. Of those tissues sampled 3 h after the last dose, relative sarafloxacin concentration was greatest in the liver (4.06 μg equivalents/g) and least in the residual carcass (1.13 μg equivalents/g), Intermediate concentrations were found in the kidney (2.04 μg equivalents/g), skinless fillet (1.71 μg equivalents/ g), and the skin (1.51 μg equivalents/g). Concentrations of sarafloxacin-equivalent residues in edible skinless fillet were consistently among the lowest of all tissues examined. The highest mean concentration of parent-equivalent material in the fillet tissue was found 12 h after administration of the last dose (2.27 μg equivalents/g) and declined thereafter, Sarafloxacin constituted between 80 and 90% of the extractable radioactive residues from the fillet homogenates. No other peaks were resolved in any of the fillet tissue samples analyzed by HPLC with in-line radiometric detection.

GEANT4 and PHITS simulations of the shielding of neutrons from the 252Cf source

NASA Astrophysics Data System (ADS)

Shin, Jae Won; Hong, Seung-Woo; Bak, Sang-In; Kim, Do Yoon; Kim, Chong Yeal

2014-09-01

Monte Carlo simulations are performed by using the GEANT4 and the PHITS for studying the neutron-shielding abilities of several materials, such as graphite, iron, polyethylene, NS-4-FR and KRAFTON-HB. As a neutron source, 252Cf is considered. For the Monte Carlo simulations by using the GEANT4, high precision (G4HP) models with the G4NDL 4.2 based on ENDF/B-VII data are used. For the simulations by using the PHITS, the JENDL-4.0 library is used. The neutron-dose-equivalent rates with or without five different shielding materials are estimated and compared with the experimental values. The differences between the shielding abilities calculated by using the GEANT4 with the G4NDL 4.2 and the PHITS with the JENDL-4.0 are found not to be significant for all the cases considered in this work. The neutron-dose-equivalent rates obtained by using the GEANT4 and the PHITS are compared with experimental data and other simulation results. Our neutron-dose-equivalent rates agree well with the experimental dose-equivalent rates, within 20% errors, except for polyethylene. For polyethylene, the discrepancies between our calculations and the experiments are less than 40%, as observed in other simulation results.

A correlation study of eye lens dose and personal dose equivalent for interventional cardiologists.

PubMed

Farah, J; Struelens, L; Dabin, J; Koukorava, C; Donadille, L; Jacob, S; Schnelzer, M; Auvinen, A; Vanhavere, F; Clairand, I

2013-12-01

This paper presents the dosimetry part of the European ELDO project, funded by the DoReMi Network of Excellence, in which a method was developed to estimate cumulative eye lens doses for past practices based on personal dose equivalent values, H(p)(10), measured above the lead apron at several positions at the collar, chest and waist levels. Measurement campaigns on anthropomorphic phantoms were carried out in typical interventional settings considering different tube projections and configurations, beam energies and filtration, operator positions and access routes and using both mono-tube and biplane X-ray systems. Measurements showed that eye lens dose correlates best with H(p)(10) measured on the left side of the phantom at the level of the collar, although this correlation implicates high spreads (41 %). Nonetheless, for retrospective dose assessment, H(p)(10) records are often the only option for eye dose estimates and the typically used chest left whole-body dose measurement remains useful.

Estimation of ambient dose equivalent distribution in the 18F-FDG administration room using Monte Carlo simulation.

PubMed

Nagamine, Shuji; Fujibuchi, Toshioh; Umezu, Yoshiyuki; Himuro, Kazuhiko; Awamoto, Shinichi; Tsutsui, Yuji; Nakamura, Yasuhiko

2017-03-01

In this study, we estimated the ambient dose equivalent rate (hereafter "dose rate") in the fluoro-2-deoxy-D-glucose (FDG) administration room in our hospital using Monte Carlo simulations, and examined the appropriate medical-personnel locations and a shielding method to reduce the dose rate during FDG injection using a lead glass shield. The line source was assumed to be the FDG feed tube and the patient a cube source. The dose rate distribution was calculated with a composite source that combines the line and cube sources. The dose rate distribution was also calculated when a lead glass shield was placed in the rear section of the lead-acrylic shield. The dose rate behind the automatic administration device decreased by 87 % with respect to that behind the lead-acrylic shield. Upon positioning a 2.8-cm-thick lead glass shield, the dose rate behind the lead-acrylic shield decreased by 67 %.

Single-dose extended-release azithromycin versus a 10-day regimen of amoxicillin/clavulanate for the treatment of children with acute otitis media.

PubMed

Arguedas, Adriano; Soley, Carolina; Kamicker, Barbara J; Jorgensen, Daniel M

2011-04-01

A randomized, double-blind, double-dummy, multicenter international study was conducted to assess the clinical and bacteriologic response, safety, and compliance of a single 60-mg/kg dose of azithromycin extended-release (ER) versus a 10-day regimen of amoxicillin/clavulanate 90/6.4 mg/kg per day in children with acute otitis media at high risk of persistent or recurrent middle ear infection. Children aged 3 to 48 months were enrolled and stratified into two age groups (≤ 24 months and >24 months). Pretreatment tympanocentesis was performed at all sites and was repeated during treatment at selected sites. The primary endpoint, clinical response at the test-of-cure visit in the bacteriologic eligible population, was achieved in 80.5% of children in the azithromycin ER group and 84.5% of children in the amoxicillin/clavulanate group (difference-3.9%; 95% confidence interval-10.4, 2.6). Bacteriologic eradication was 82.6% in the azithromycin ER group and 92% in the amoxicillin/clavulanate group (p=0.050). Children who received amoxicillin/clavulanate had significantly higher rates of dermatitis and diarrhea, a greater burden of adverse events, and a lower rate of compliance to study drug compared to those who received azithromycin ER. A single 60-mg/kg dose of azithromycin ER provides near equivalent effectiveness to a 10-day regimen of amoxicillin/clavulanate 90/6.4 mg/kg per day in the treatment of children with acute otitis media. Copyright © 2011 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

In vivo characterization of Lactobacillus johnsonii FI9785 for use as a defined competitive exclusion agent against bacterial pathogens in poultry.

PubMed

La Ragione, R M; Narbad, A; Gasson, M J; Woodward, M J

2004-01-01

To test the efficacy of Lactobacillus johnsonii FI9785 in reducing the colonization and shedding of Salmonella enterica serotype Enteritidis, Escherichia coli O78:K80 and Clostridium perfringens in poultry. Specific pathogen-free chicks (1 day old) were dosed with a single oral inoculum of 1x10(9) CFU. Lactobacillus johnsonii FI9785 and 24 h later were challenged in separate experiments with S. Enteritidis (S1400, nalr) and E. coli O78:K80 (EC34195, nalr). There were no significant effects against S. Enteritidis whereas colonization of the small intestine by E. coli O78:K80 was reduced significantly. Both S. Enteritidis and E. coli colonized the caeca and colon to levels equivalent to control birds and there was no reduction in shedding as assessed by a semi-quantitative cloacal swabbing technique. Specific pathogen-free chicks (20 day old) were dosed with a single oral inoculum of 1x10(9) CFU L. johnsonii FI9785 and 24 h later were challenged with C. perfringens. A single oral dose of L. johnsonii FI9785 was sufficient to suppress all aspects of colonization and persistence of C. perfringens. Lactobacillus johnsonii FI9785 may be given to poultry for use as a competitive exclusion agent to control C. perfringens. Lactobacillus johnsonii FI9785 may be a valuable tool to control the endemic disease of necrotic enteritis, thereby reducing economic losses associated with reduced use of antimicrobials in the poultry industry.

An analysis of interplanetary space radiation exposure for various solar cycles

NASA Technical Reports Server (NTRS)

Badhwar, G. D.; Cucinotta, F. A.; O'Neill, P. M.; Wilson, J. W. (Principal Investigator)

1994-01-01

The radiation dose received by crew members in interplanetary space is influenced by the stage of the solar cycle. Using the recently developed models of the galactic cosmic radiation (GCR) environment and the energy-dependent radiation transport code, we have calculated the dose at 0 and 5 cm water depth; using a computerized anatomical man (CAM) model, we have calculated the skin, eye and blood-forming organ (BFO) doses as a function of aluminum shielding for various solar minima and maxima between 1954 and 1989. These results show that the equivalent dose is within about 15% of the mean for the various solar minima (maxima). The maximum variation between solar minimum and maximum equivalent dose is about a factor of three. We have extended these calculations for the 1976-1977 solar minimum to five practical shielding geometries: Apollo Command Module, the least and most heavily shielded locations in the U.S. space shuttle mid-deck, center of the proposed Space Station Freedom cluster and sleeping compartment of the Skylab. These calculations, using the quality factor of ICRP 60, show that the average CAM BFO equivalent dose is 0.46 Sv/year. Based on an approach that takes fragmentation into account, we estimate a calculation uncertainty of 15% if the uncertainty in the quality factor is neglected.

Pediatric Phantom Dosimetry of Kodak 9000 Cone-beam Computed Tomography.

PubMed

Yepes, Juan F; Booe, Megan R; Sanders, Brian J; Jones, James E; Ehrlich, Ygal; Ludlow, John B; Johnson, Brandon

2017-05-15

The purpose of the study was to evaluate the radiation dose of the Kodak 9000 cone-beam computed tomography (CBCT) device for different anatomical areas using a pediatric phantom. Absorbed doses resulting from maxillary and mandibular region three by five cm CBCT volumes of an anthropomorphic 10-year-old child phantom were acquired using optical stimulated dosimetry. Equivalent doses were calculated for radiosensitive tissues in the head and neck area, and effective dose for maxillary and mandibular examinations were calculated following the 2007 recommendations of the International Commission on Radiological Protection (ICRP). Of the mandibular scans, the salivary glands had the highest equivalent dose (1,598 microsieverts [μSv]), followed by oral mucosa (1,263 μSv), extrathoracic airway (pharynx, larynx, and trachea; 859 μSv), and thyroid gland (578 μSv). For the maxilla, the salivary glands had the highest equivalent dose (1,847 μSv), followed closely by oral mucosa (1,673 μSv), followed by the extrathoracic airway (pharynx, larynx, and trachea; 1,011 μSv) and lens of the eye (202 μSv). Compared to previous research of the Kodak 9000, completed with the adult phantom, a child receives one to three times more radiation for mandibular scans and two to 10 times more radiation for maxillary scans.

Interplay effects in proton scanning for lung: a 4D Monte Carlo study assessing the impact of tumor and beam delivery parameters.

PubMed

Dowdell, S; Grassberger, C; Sharp, G C; Paganetti, H

2013-06-21

Relative motion between a tumor and a scanning proton beam results in a degradation of the dose distribution (interplay effect). This study investigates the relationship between beam scanning parameters and the interplay effect, with the goal of finding parameters that minimize interplay. 4D Monte Carlo simulations of pencil beam scanning proton therapy treatments were performed using the 4DCT geometry of five lung cancer patients of varying tumor size (50.4-167.1 cc) and motion amplitude (2.9-30.1 mm). Treatments were planned assuming delivery in 35 × 2.5 Gy(RBE) fractions. The spot size, time to change the beam energy (τes), time required for magnet settling (τss), initial breathing phase, spot spacing, scanning direction, scanning speed, beam current and patient breathing period were varied for each of the five patients. Simulations were performed for a single fraction and an approximation of conventional fractionation. For the patients considered, the interplay effect could not be predicted using the superior-inferior motion amplitude alone. Larger spot sizes (σ ~ 9-16 mm) were less susceptible to interplay, giving an equivalent uniform dose (EUD) of 99.0 ± 4.4% (1 standard deviation) in a single fraction compared to 86.1 ± 13.1% for smaller spots (σ ~ 2-4 mm). The smaller spot sizes gave EUD values as low as 65.3% of the prescription dose in a single fraction. Reducing the spot spacing improved the target dose homogeneity. The initial breathing phase can have a significant effect on the interplay, particularly for shorter delivery times. No clear benefit was evident when scanning either parallel or perpendicular to the predominant axis of motion. Longer breathing periods decreased the EUD. In general, longer delivery times led to lower interplay effects. Conventional fractionation showed significant improvement in terms of interplay, giving a EUD of at least 84.7% and 100.0% of the prescription dose for the small and larger spot sizes respectively. The interplay effect is highly patient specific, depending on the motion amplitude, tumor location and the delivery parameters. Large degradations of the dose distribution in a single fraction were observed, but improved significantly using conventional fractionation.

Interplay effects in proton scanning for lung: A 4D Monte Carlo study assessing the impact of tumor and beam delivery parameters

PubMed Central

Dowdell, S; Grassberger, C; Sharp, G C; Paganetti, H

2013-01-01

Relative motion between a tumor and a scanning proton beam results in a degradation of the dose distribution (interplay effect). This study investigates the relationship between beam scanning parameters and the interplay effect, with the goal of finding parameters that minimize interplay. 4D Monte Carlo simulations of pencil beam scanning proton therapy treatments were performed using the 4DCT geometry of 5 lung cancer patients of varying tumor size (50.4–167.1cc) and motion amplitude (2.9–30.1mm). Treatments were planned assuming delivery in 35×2.5Gy(RBE) fractions. The spot size, time to change the beam energy (τes), time required for magnet settling (τss), initial breathing phase, spot spacing, scanning direction, scanning speed, beam current and patient breathing period were varied for each of the 5 patients. Simulations were performed for a single fraction and an approximation of conventional fractionation. For the patients considered, the interplay effect could not be predicted using the superior-inferior (SI) motion amplitude alone. Larger spot sizes (σ ~9–16mm) were less susceptible to interplay, giving an equivalent uniform dose (EUD) of 99.0±4.4% (1 standard deviation) in a single fraction compared to 86.1±13.1% for smaller spots (σ ~2–4mm). The smaller spot sizes gave EUD values as low as 65.3% of the prescription dose in a single fraction. Reducing the spot spacing improved the target dose homogeneity. The initial breathing phase can have a significant effect on the interplay, particularly for shorter delivery times. No clear benefit was evident when scanning either parallel or perpendicular to the predominant axis of motion. Longer breathing periods decreased the EUD. In general, longer delivery times led to lower interplay effects. Conventional fractionation showed significant improvement in terms of interplay, giving a EUD of at least 84.7% and 100.0% of the prescription dose for the small and larger spot sizes respectively. The interplay effect is highly patient specific, depending on the motion amplitude, tumor location and the delivery parameters. Large degradations of the dose distribution in a single fraction were observed, but improved significantly using conventional fractionation. PMID:23689035

Comparison of organ dose and dose equivalent using ray tracing of male and female Voxel phantoms to space flight phantom torso data

NASA Astrophysics Data System (ADS)

Kim, Myung-Hee; Qualls, Garry; Slaba, Tony; Cucinotta, Francis A.

Phantom torso experiments have been flown on the space shuttle and International Space Station (ISS) providing validation data for radiation transport models of organ dose and dose equivalents. We describe results for space radiation organ doses using a new human geometry model based on detailed Voxel phantoms models denoted for males and females as MAX (Male Adult voXel) and Fax (Female Adult voXel), respectively. These models represent the human body with much higher fidelity than the CAMERA model currently used at NASA. The MAX and FAX models were implemented for the evaluation of directional body shielding mass for over 1500 target points of major organs. Radiation exposure to solar particle events (SPE), trapped protons, and galactic cosmic rays (GCR) were assessed at each specific site in the human body by coupling space radiation transport models with the detailed body shielding mass of MAX/FAX phantom. The development of multiple-point body-shielding distributions at each organ site made it possible to estimate the mean and variance of space dose equivalents at the specific organ. For the estimate of doses to the blood forming organs (BFOs), active marrow distributions in adult were accounted at bone marrow sites over the human body. We compared the current model results to space shuttle and ISS phantom torso experiments and to calculations using the CAMERA model.

Comparison of Organ Dose and Dose Equivalent Using Ray Tracing of Male and Female Voxel Phantoms to Space Flight Phantom Torso Data

NASA Technical Reports Server (NTRS)

Kim, Myung-Hee Y.; Qualls, Garry D.; Cucinotta, Francis A.

2008-01-01

Phantom torso experiments have been flown on the space shuttle and International Space Station (ISS) providing validation data for radiation transport models of organ dose and dose equivalents. We describe results for space radiation organ doses using a new human geometry model based on detailed Voxel phantoms models denoted for males and females as MAX (Male Adult voXel) and Fax (Female Adult voXel), respectively. These models represent the human body with much higher fidelity than the CAMERA model currently used at NASA. The MAX and FAX models were implemented for the evaluation of directional body shielding mass for over 1500 target points of major organs. Radiation exposure to solar particle events (SPE), trapped protons, and galactic cosmic rays (GCR) were assessed at each specific site in the human body by coupling space radiation transport models with the detailed body shielding mass of MAX/FAX phantom. The development of multiple-point body-shielding distributions at each organ site made it possible to estimate the mean and variance of space dose equivalents at the specific organ. For the estimate of doses to the blood forming organs (BFOs), active marrow distributions in adult were accounted at bone marrow sites over the human body. We compared the current model results to space shuttle and ISS phantom torso experiments and to calculations using the CAMERA model.

Dose of radiation enhancement, using silver nanoparticles in a human tissue equivalent gel dosimeter.

PubMed

Hassan, Muhammad; Waheed, Muhammad Mohsin; Anjum, Muhammad Naeem

2016-01-01

To quantify the radiation dose enhancement in a human tissue-equivalent polymer gel impregnated with silver nanoparticles. The case-control study was conducted at the Bahawalpur Institute of Nuclear Medicine and Oncology, Bahawalpur, Pakistan, in January 2014. Silver nanoparticles used in this study were prepared by wet chemical method. Polymer gel was prepared by known quantity of gelatine, methacrylic acid, ascorbic acid, copper sulphate pentahydrate, hydroquinone and water. Different concentrations of silver nanoparticles were added to the gel during its cooling process. The gel was cooled in six plastic vials of 50ml each. Two vials were used as a control sample while four vials were impregnated with silver nanoparticles. After 22 hours, the vials were irradiated with gamma rays by aCobalt-60 unit. Radiation enhancement was assessed by taking magnetic resonance images of the vials. The images were analysed using Image J software. The dose enhancement factor was 24.17% and 40.49% for 5Gy and 10Gy dose respectively. The dose enhancement factor for the gel impregnated with 0.10mM silver nanoparticles was 32.88% and 51.98% for 5Gy and 10Gy dose respectively. The impregnation of a tissue-equivalent gel with silver nanoparticles resulted in dose enhancement and this effect was magnified up to a certain level with the increase in concentration of silver nanoparticles.

Dosimetric impacts of microgravity: an analysis of 5th, 50th and 95th percentile male and female astronauts

NASA Astrophysics Data System (ADS)

Bahadori, Amir A.; Van Baalen, Mary; Shavers, Mark R.; Semones, Edward J.; Bolch, Wesley E.

2012-02-01

Computational phantoms serve an important role in organ dosimetry and risk assessment performed at the National Aeronautics and Space Administration (NASA). A previous study investigated the impact on organ dose equivalents and effective doses from the use of the University of Florida hybrid adult male (UFHADM) and adult female (UFHADF) phantoms at differing height and weight percentiles versus those given by the two existing NASA phantoms, the computerized anatomical man (CAM) and female (CAF) (Bahadori et al 2011 Phys. Med. Biol. 56 1671-94). In the present study, the UFHADM and UFHADF phantoms of different body sizes were further altered to incorporate the effects of microgravity. Body self-shielding distributions are generated using the voxel-based ray tracer (VoBRaT), and the results are combined with depth dose data from the NASA codes BRYNTRN and HZETRN to yield organ dose equivalents and their rates for a variety of space radiation environments. It is found that while organ dose equivalents are indeed altered by the physiological effects of microgravity, the magnitude of the change in overall risk (indicated by the effective dose) is minimal for the spectra and simplified shielding configurations considered. The results also indicate, however, that UFHADM and UFHADF could be useful in designing dose reduction strategies through optimized positioning of an astronaut during encounters with solar particle events.

SU-F-T-151: Measurement Evaluation of Skin Dose in Scanning Proton Beam Therapy for Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, J; Nichols, E; Strauss, D

Purpose: To measure the skin dose and compare it with the calculated dose from a treatment planning system (TPS) for breast cancer treatment using scanning proton beam therapy (SPBT). Methods: A single en-face-beam SPBT plan was generated by a commercial TPS for two breast cancer patients. The treatment volumes were the entire breasts (218 cc and 1500 cc) prescribed to 50.4 Gy (RBE) in 28 fractions. A range shifter of 5 cm water equivalent thickness was used. The organ at risk (skin) was defined to be 5 mm thick from the surface. The skin doses were measured in water withmore » an ADCL calibrated parallel plate (PP) chamber. The measured data were compared with the values calculated in the TPS. Skin dose calculations can be subject to uncertainties created by the definition of the external contour and the limitations of the correction based algorithms, such as proton convolution superposition. Hence, the external contours were expanded by 0, 3 mm and 1 cm to include additional pixels for dose calculation. In addition, to examine the effects of the cloth gown on the skin dose, the skin dose measurements were conducted with and without gown. Results: On average the measured skin dose was 4% higher than the calculated values. At deeper depths, the measured and calculated doses were in better agreement (< 2%). Large discrepancy occur for the dose calculated without external expansion due to volume averaging. The addition of the gown only increased the measured skin dose by 0.4%. Conclusion: The implemented TPS underestimated the skin dose for breast treatments. Superficial dose calculation without external expansion would result in large errors for SPBT for breast cancer.« less

Estimation of thyroid equivalent doses during evacuation based on body surface contamination levels in the nuclear accident of FDNPS in 2011

NASA Astrophysics Data System (ADS)

Ohba, Takashi; Hasegawa, Arifumi; Kohayakawa, Yoshitaka; Kondo, Hisayoshi; Suzuki, Gen

2017-09-01

To reduce uncertainty in thyroid dose estimation, residents' radiation protection behavior should be reflected in the estimation. Screening data of body surface contamination provide information on exposure levels during evacuation. Our purpose is to estimate thyroid equivalent doses based on body surface contamination levels using a new methodology. We obtained a record of 7,539 residents/evacuees. Geiger-Mueller survey meter measurement value in cpm was translated into Bq/cm2 according to the nuclides densities obtained by measuring clothing from two persons by germanium γ-spectrometer. The measurement value of body surface contamination on head was adjusted by a natural removal rate of 15 hours and radionuclides' physical half-life. Thyroid equivalent dose of 1-year-old children by inhalation was estimated by two-dimensional Monte Carlo simulation. The proportions of evacuees/residents with measurement value in cpm of Namie and Minamisoma groups were higher than those of other groups during both periods (p<0.01, Kruskal-Wallis). During 12-14 March period, 50 and 95 percentiles of thyroid equivalent doses by inhalation were estimated as 2.7 and 86.0 mSv, respectively, for Namie group, and 4.2 and 17.2 mSv, respectively, for Minamisoma group, 0.1 and 1.0 mSv, respectively, for Tomioka/Okuma/Futaba/Naraha group, and 0.2 and 2.1 mSv, respectively, for the other group. During 15- 17 March period, 50 and 95 percentiles of thyroid equivalent doses by inhalation were 0.8 and 15.7 mSv, respectively, for Namie group, and 1.6 and 8.4 mSv, respectively, for Minamisoma group, 0.2 and 13.2 mSv, respectively, for Tomioka/Okuma/Futaba/Naraha group, and 1.2 and 12.7 mSv, respectively, for the other group. It was indicated that inhalation dose was generally higher in Namie and Minamisoma groups during 12-14 March than those during 15-17 March might reflect different self-protective behavior to radioactive plumes from other groups.

Personal Dose Equivalent Conversion Coefficients For Photons To 1 GEV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veinot, K. G.; Hertel, N. E.

2010-09-27

The personal dose equivalent, H{sub p}(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity Effective Dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk where personal dosemeters are usually worn and in this instance a suitable approximation is a 30 cm X 30 cm X 15 cm slab-type phantom. For this condition the personal dose equivalent is denoted as H{sub p,slab}(d) and the depths,more » d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several MeV, however, data to higher energies are limited. In this work conversion coefficients up to 1 GeV have been calculated for H{sub p,slab}(10) and H{sub p,slab}(3) using both the kerma approximation and by tracking secondary charged particles. For H{sub p}(0.07) the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H{sub p,slab}(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared to the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection (ICRP) guidance.« less

General requirements to implement the personal dose equivalent Hp(10) in Brazil

NASA Astrophysics Data System (ADS)

Gomes Lopes, Amanda; Da Silva, Francisco Cesar Augusto

2018-03-01

To update the dosimetry quantity with the international community, Brazil is changing the Individual Dose (Hx) to the Personal Dose Equivalent Hp(10). A bibliographical survey on the technical and administrative requirements of nine countries that use Hp(10) was carried out to obtain the most relevant ones. All of them follow IEC and ISO guidelines for technical requirements, but administrative requirements change from country to country. Based on countries experiences, this paper presents a list of important general requirements to implement Hp(10) and to prepare the Brazilian requirements according to the international scientific community.

Mesoscopic in vivo 3-D tracking of sparse cell populations using angular multiplexed optical projection tomography

PubMed Central

Chen, Lingling; Alexandrov, Yuriy; Kumar, Sunil; Andrews, Natalie; Dallman, Margaret J.; French, Paul M. W.; McGinty, James

2015-01-01

We describe an angular multiplexed imaging technique for 3-D in vivo cell tracking of sparse cell distributions and optical projection tomography (OPT) with superior time-lapse resolution and a significantly reduced light dose compared to volumetric time-lapse techniques. We demonstrate that using dual axis OPT, where two images are acquired simultaneously at different projection angles, can enable localization and tracking of features in 3-D with a time resolution equal to the camera frame rate. This is achieved with a 200x reduction in light dose compared to an equivalent volumetric time-lapse single camera OPT acquisition with 200 projection angles. We demonstrate the application of this technique to mapping the 3-D neutrophil migration pattern observed over ~25.5 minutes in a live 2 day post-fertilisation transgenic LysC:GFP zebrafish embryo following a tail wound. PMID:25909009

Mesoscopic in vivo 3-D tracking of sparse cell populations using angular multiplexed optical projection tomography.

PubMed

Chen, Lingling; Alexandrov, Yuriy; Kumar, Sunil; Andrews, Natalie; Dallman, Margaret J; French, Paul M W; McGinty, James

2015-04-01

We describe an angular multiplexed imaging technique for 3-D in vivo cell tracking of sparse cell distributions and optical projection tomography (OPT) with superior time-lapse resolution and a significantly reduced light dose compared to volumetric time-lapse techniques. We demonstrate that using dual axis OPT, where two images are acquired simultaneously at different projection angles, can enable localization and tracking of features in 3-D with a time resolution equal to the camera frame rate. This is achieved with a 200x reduction in light dose compared to an equivalent volumetric time-lapse single camera OPT acquisition with 200 projection angles. We demonstrate the application of this technique to mapping the 3-D neutrophil migration pattern observed over ~25.5 minutes in a live 2 day post-fertilisation transgenic LysC:GFP zebrafish embryo following a tail wound.

Randomized controlled trial of web-based alcohol screening and brief intervention in primary care.

PubMed

Kypri, Kypros; Langley, John D; Saunders, John B; Cashell-Smith, Martine L; Herbison, Peter

2008-03-10

There is compelling evidence supporting screening and brief intervention (SBI) for hazardous drinking, yet it remains underused in primary health care. Electronic (computer or Web-based) SBI (e-SBI) offers the prospects of ease and economy of access. We sought to determine whether e-SBI reduces hazardous drinking. We conducted a randomized controlled trial in a university primary health care service. Participants were 975 students (age range, 17-29 years) screened using the Alcohol Use Disorders Identification Test (AUDIT). Of 599 students who scored in the hazardous or harmful range, 576 (300 of whom were women) consented to the trial and were randomized to receive an information pamphlet (control group), a Web-based motivational intervention (single-dose e-SBI group), or a Web-based motivational intervention with further interventions 1 and 6 months later (multidose e-SBI group). Relative to the control group, the single-dose e-SBI group at 6 months reported a lower frequency of drinking (rate ratio [RR], 0.79; 95% confidence interval [CI], 0.68-0.94), less total consumption (RR, 0.77; 95% CI, 0.63-0.95), and fewer academic problems (RR, 0.76; 95% CI, 0.64-0.91). At 12 months, statistically significant differences in total consumption (RR, 0.77; 95% CI, 0.63-0.95 [equivalent to 3.5 standard drinks per week]) and in academic problems (RR, 0.80; 95% CI, 0.66-0.97) remained, and the AUDIT scores were 2.17 (95% CI, -1.10 to -3.24) points lower. Relative to the control group, the multidose e-SBI group at 6 months reported a lower frequency of drinking (RR, 0.85; 95% CI, 0.73-0.98), less total consumption (RR, 0.79; 95% CI, 0.64-0.97 [equivalent to 3.0 standard drinks per week]), reduced episodic heavy drinking (RR, 0.65; 95% CI, 0.45-0.93), and fewer academic problems (RR, 0.78; 95% CI, 0.65-0.93). At 12 months, statistically significant differences in academic problems remained (RR, 0.75; 95% CI, 0.62-0.90), while the AUDIT scores were 2.02 (95% CI, -0.97 to -3.10) points lower. Single-dose e-SBI reduces hazardous drinking, and the effect lasts 12 months. Additional sessions seem not to enhance the effect. Trial Registration www.anzctr.org.au Identifier:ACTRN012607000103460.

Dose Calibration of the ISS-RAD Fast Neutron Detector

NASA Technical Reports Server (NTRS)

Zeitlin, C.

2015-01-01

The ISS-RAD instrument has been fabricated by Southwest Research Institute and delivered to NASA for flight to the ISS in late 2015 or early 2016. ISS-RAD is essentially two instruments that share a common interface to ISS. The two instruments are the Charged Particle Detector (CPD), which is very similar to the MSL-RAD detector on Mars, and the Fast Neutron Detector (FND), which is a boron-loaded plastic scintillator with readout optimized for the 0.5 to 10 MeV energy range. As the FND is completely new, it has been necessary to develop methodology to allow it to be used to measure the neutron dose and dose equivalent. This talk will focus on the methods developed and their implementation using calibration data obtained in quasi-monoenergetic (QMN) neutron fields at the PTB facility in Braunschweig, Germany. The QMN data allow us to determine an approximate response function, from which we estimate dose and dose equivalent contributions per detected neutron as a function of the pulse height. We refer to these as the "pSv per count" curves for dose equivalent and the "pGy per count" curves for dose. The FND is required to provide a dose equivalent measurement with an accuracy of ?10% of the known value in a calibrated AmBe field. Four variants of the analysis method were developed, corresponding to two different approximations of the pSv per count curve, and two different implementations, one for real-time analysis onboard ISS and one for ground analysis. We will show that the preferred method, when applied in either real-time or ground analysis, yields good accuracy for the AmBe field. We find that the real-time algorithm is more susceptible to chance-coincidence background than is the algorithm used in ground analysis, so that the best estimates will come from the latter.

A Methodology to Compare Insulin Dosing Recommendations in Real-Life Settings.

PubMed

Groat, Danielle; Grando, Maria A; Thompson, Bithika; Neto, Pedro; Soni, Hiral; Boyle, Mary E; Bailey, Marilyn; Cook, Curtiss B

2017-11-01

We propose a methodology to analyze complex real-life glucose data in insulin pump users. Patients with type 1 diabetes (T1D) on insulin pumps were recruited from an academic endocrinology practice. Glucose data, insulin bolus (IB) amounts, and self-reported alcohol consumption and exercise events were collected for 30 days. Rules were developed to retrospectively compare IB recommendations from the insulin pump bolus calculator (IPBC) against recommendations from a proposed decision aid (PDA) and for assessing the PDA's recommendation for exercise and alcohol. Data from 15 participants were analyzed. When considering instances where glucose was below target, the PDA recommended a smaller dose in 14%, but a larger dose in 13% and an equivalent IB in 73%. For glucose levels at target, the PDA suggested an equivalent IB in 58% compared to the subject's IPBC, but higher doses in 20% and lower in 22%. In events where postprandial glucose was higher than target, the PDA suggested higher doses in 25%, lower doses in 13%, and equivalent doses in 62%. In 64% of all alcohol events the PDA would have provided appropriate advice. In 75% of exercise events, the PDA appropriately advised an IB, a carbohydrate snack, or neither. This study provides a methodology to systematically analyze real-life data generated by insulin pumps and allowed a preliminary analysis of the performance of the PDA for insulin dosing. Further testing of the methodological approach in a broader diabetes population and prospective testing of the PDA are needed.

Estimation of chloroform inhalation dose by other routes based on the relationship of area under the blood concentration-time curve (AUC)-inhalation dose to chloroform distribution in the blood of rats.

PubMed

Take, Makoto; Takeuchi, Tetsuya; Haresaku, Mitsuru; Matsumoto, Michiharu; Nagano, Kasuke; Yamamoto, Seigo; Takamura-Enya, Takeji; Fukushima, Shoji

2014-01-01

The present study investigated the time-course changes of concentration of chloroform (CHCl3) in the blood during and after exposure of male rats to CHCl3 by inhalation. Increasing the dose of CHCl3 in the inhalation exposed groups caused a commensurate increase in the concentration of CHCl3 in the blood and the area under the blood concentration-time curve (AUC). There was good correlation (r = 0.988) between the inhalation dose and the AUC/kg body weight. Based on the AUC/kg body weight-inhalation dose curve and the AUC/kg body weight after oral administration, inhalation equivalent doses of orally administered CHCl3 were calculated. Calculation of inhalation equivalent doses allows the body burden due to CHCl3 by inhalation exposure and oral exposure to be directly compared. This type of comparison facilitates risk assessment in humans exposed to CHCl3 by different routes. Our results indicate that when calculating inhalation equivalent doses of CHCl3, it is critical to include the AUC from the exposure period in addition to the AUC after the end of the exposure period. Thus, studies which measure the concentration of volatile organic compounds in the blood during the inhalation exposure period are crucial. The data reported here makes an important contribution to the physiologically based pharmacokinetic (PBPK) database of CHCl3 in rodents.

Dose reduction in molecular breast imaging

NASA Astrophysics Data System (ADS)

Wagenaar, Douglas J.; Chowdhury, Samir; Hugg, James W.; Moats, Rex A.; Patt, Bradley E.

2011-10-01

Molecular Breast Imaging (MBI) is the imaging of radiolabeled drugs, cells, or nanoparticles for breast cancer detection, diagnosis, and treatment. Screening of broad populations of women for breast cancer with mammography has been augmented by the emergence of breast MRI in screening of women at high risk for breast cancer. Screening MBI may benefit the sub-population of women with dense breast tissue that obscures small tumors in mammography. Dedicated breast imaging equipment is necessary to enable detection of early-stage tumors less than 1 cm in size. Recent progress in the development of these instruments is reviewed. Pixellated CZT for single photon MBI imaging of 99mTc-sestamibi gives high detection sensitivity for early-stage tumors. The use of registered collimators in a near-field geometry gives significantly higher detection efficiency - a factor of 3.6-, which translates into an equivalent dose reduction factor given the same acquisition time. The radiation dose in the current MBI procedure has been reduced to the level of a four-view digital mammography study. In addition to screening of selected sub-populations, reduced MBI dose allows for dual-isotope, treatment planning, and repeated therapy assessment studies in the era of molecular medicine guided by quantitative molecular imaging.

Dose estimates for the 1104 m APS storage ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moe, H.J.

1989-06-01

The estimated dose equivalent rates outside the shielded storage ring, and the estimated annual dose equivalent to members of the public due to direct radiation and skyshine from the ring, have been recalculated. The previous estimates found in LS-84 (MOE 87) and cited in the 1987 Conceptual Design Report of the APS (ANL 87) required revision because of changes in the ring circumference and in the proposed location of the ring with respect to the nearest site boundary. The values assumed for the neutron quality factors were also overestimated (by a factor of 2) in the previous computation, and themore » correct values have been used for this estimate. The methodology used to compute dose and dose rate from the storage ring is the same as that used in LS-90 (MOE 87a). The calculations assumed 80 cm thick walls of ordinary concrete (or the shielding equivalent of this) and a roof thickness of 1 meter of ordinary concrete. The circumference of the ring was increased to 1,104 m, and the closest distance to the boundary was taken as 140 m. The recalculation of the skyshine component used the same methodology as that used in LS-84.« less

The Pharmacokinetics of the CYP3A Substrate Midazolam After Steady-state Dosing of Delafloxacin.

PubMed

Paulson, Susan K; Wood-Horrall, Rebecca N; Hoover, Randall; Quintas, Megan; Lawrence, Laura E; Cammarata, Sue K

2017-06-01

Delafloxacin is a novel anionic fluoroquinolone in Phase III development for the treatment of serious skin infections. The objective of this study was to evaluate the effects of delafloxacin on the pharmacokinetics of midazolam, a cytochrome P450 (CYP) 3A substrate. CYP3A activity using midazolam as a probe was assessed before and after multiple doses of delafloxacin to reach steady state. In this nonrandomized, open-label, single-sequence, Phase I study, 22 healthy male and female subjects were administered a single 5-mg oral dose of midazolam on days 1 and 8, with oral delafloxacin 450 mg every 12 hours administered from days 3 to 8. Full pharmacokinetic profiles were obtained on days 1 and 8 (midazolam and 1-hydroxymidazolam) and days 3 and 7 (delafloxacin). The geometric mean ratios (90% CIs) for AUC 0-∞ and C max of midazolam coadministered with delafloxacin versus midazolam alone were 89.4 (83.2-96.0) and 93.6 (83.7-104.6). Similarly, the geometric ratio for the AUC 0-∞ of 1-hydroxymidazolam, the primary metabolite of midazolam, was 105.7 (97.7-114.3); the ratio of C max was not equivalent at 116.1 (101.7-132.4), which was outside the CI of 80% to 125%. Multiple doses of oral delafloxacin for 6 days were generally well tolerated. Steady-state dosing of delafloxacin produced no significant changes in midazolam pharmacokinetics, except for a small but not clinically relevant change in the C max of 1-hydroxymidazolam. ClinicalTrials.gov identifier: NCT02505997. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

SU-E-J-158: Experimental Investigation of Proton Radiography Based On Time-Resolved Dose Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Testa, M; Paganetti, H; Lu, H-M

2014-06-01

Purpose: To use proton radiography for i) in-vivo range verification of the brain fields of medulloblastoma patients in order to reduce the exit dose to the cranial skin and thus the risk of permanent alopecia; ii) for performing patient specific optimization of the calibration from CT-Hounsfield units to proton relative stopping power in order to minimize uncertainties of proton rang Methods: We developed and tested a prototype proton radiography system based on a single-plane scintillation screen coupled with a fast CCD camera (1ms sampling rate, 0.29x0.29 mm{sup 2} pixel size, 30×30 cm{sup 2} field of view). The method is basedmore » on the principle that, for passively scattered beams, the radiological depth of any point in the plateau of a spread-out Bragg-Peak (SOBP) can be inferred from the time-pattern of the dose rate measurements. We performed detector characterization measurements using complex-shape homogeneous phantoms and an Alderson phanto Results: Detector characterization tests confirmed the robustness of the technique. The results of the phantom measurements are encouraging in terms of achievable accuracy of the water equivalent thickness. A technique to minimize the degradation of spatial resolution due to multiple Coulomb scattering is discussed. Our novel radiographic technique is rapid (100 ms) and simultaneous over the whole field. The dose required to produce one radiograph, with the current settings, is ∼3 cG Conclusion: The results obtained with this simple and innovative radiography method are promising and motivate further development of technique. The system requires only a single-plane 2D dosimeter and it uses the clinical beam for a fraction of second with low dose to the patient.« less

Evaluation of dose delivery accuracy of gamma knife using MRI polymer gel dosimeter in an inhomogeneous phantom

NASA Astrophysics Data System (ADS)

Pourfallah T, A.; Alam N, Riahi; M, Allahverdi; M, Ay; M, Zahmatkesh

2009-05-01

Polymer gel dosimetry is still the only dosimetry method for directly measuring three-dimensional dose distributions. MRI Polymer gel dosimeters are tissue equivalent and can act as a phantom material. Because of high dose response sensitivity, the MRI was chosen as readout device. In this study dose profiles calculated with treatment-planning software (LGP) and measurements with the MR polymer gel dosimeter for single-shot irradiations were compared. A custom-built 16 cm diameter spherical plexiglas head phantom was used in this study. Inside the phantom, there is a cubic cutout for insertion of gel phantoms and another cutout for inserting the inhomogeneities. The phantoms were scanned with a 1.5T MRI (Siemens syngo MR 2004A 4VA25A) scanner. The multiple spin-echo sequence with 32 echoes was used for the MRI scans. Calibration relations between the spin-spin relaxation rate and the absorbed dose were obtained by using small cylindrical vials, which were filled with the PAGAT polymer gel from the same batch as for the spherical phantom. 1D and 2D data obtained using gel dosimeter for homogeneous and inhomogeneous phantoms were compared with dose obtained using LGP calculation. The distance between relative isodose curves obtained for homogeneous phantom and heterogeneous phantoms exceed the accepted total positioning error (>±2mm). The findings of this study indicate that dose measurement using PAGAT gel dosimeter can be used for verifying dose delivering accuracy in GK unit in presence of inhomogeneities.

Pharmacokinetic evaluation of avicularin using a model-based development approach.

PubMed

Buqui, Gabriela Amaral; Gouvea, Dayana Rubio; Sy, Sherwin K B; Voelkner, Alexander; Singh, Ravi S P; da Silva, Denise Brentan; Kimura, Elza; Derendorf, Hartmut; Lopes, Norberto Peporine; Diniz, Andrea

2015-03-01

The aim of this study was to use the pharmacokinetic information of avicularin in rats to project a dose for humans using allometric scaling. A highly sensitive and specific bioanalytical assay to determine avicularin concentrations in the plasma was developed and validated for UPLC-MS/MS. The plasma protein binding of avicularin in rat plasma determined by the ultrafiltration method was 64%. The pharmacokinetics of avicularin in nine rats was studied following an intravenous bolus administration of 1 mg/kg and was found to be best described by a two-compartment model using a nonlinear mixed effects modeling approach. The pharmacokinetic parameters were allometrically scaled by body weight and centered to the median rat weight of 0.23 kg, with the power coefficient fixed at 0.75 for clearance and 1 for volume parameters. Avicularin was rapidly eliminated from the systemic circulation within 1 h post-dose, and the avicularin pharmacokinetic was linear up to 5 mg/kg based on exposure comparison to literature data for a 5-mg/kg single dose in rats. Using allometric scaling and Monte Carlo simulation approaches, the rat doses of 1 and 5 mg/kg correspond to the human equivalent doses of 30 and 150 mg, respectively, to achieve comparable plasma avicularin concentrations in humans. Georg Thieme Verlag KG Stuttgart · New York.

LuminoTox as a tool to optimize ozone doses for the removal of contaminants and their associated toxicity.

PubMed

Marshall, Meghan; Yargeau, Viviane

2018-03-01

New treatment technologies and quality monitoring tools are needed for Contaminants of Emerging Concern (CECs) in wastewater. The purpose of this work was to assess the LuminoTox as a monitoring tool for CEC-associated toxicity in municipal wastewater during ozone treatment, and to evaluate the impact of different ozone feed concentrations at equivalent ozone doses for removing toxicity. The LuminoTox was sensitive at monitoring changes in toxicity of atrazine (ATZ) in synthetic wastewater (SWW) and in a 14 CECs mix in secondary effluent (SE) during ozone treatment. In both experiments, a decrease in toxicity was observed with increasing transferred ozone dose, which corresponded to a decrease in CEC concentration. For ATZ in SWW, a 5 ppm ozone feed showed better toxicity removal, up to 25% and 35% inhibition for LuminoTox algae biosensors SAPS I and SAPS II, respectively, for statistically equivalent ozone dose pairs of 43 mg (5 ppm ozone feed) and 36 mg (15 ppm ozone feed). The opposite was true for the 14 CECs in SE; the 15 ppm ozone feed showed better toxicity removal, up to a reduction of 37% and 40% for SAPS I and SAPS II inhibition, respectively, for statistically equivalent ozone dose pairs of 42 mg (5 ppm ozone feed) and 42 mg (15 ppm ozone feed). Different feed applications had an impact on the efficiency of toxicity removal for equivalent ozone doses; this efficiency appears to depend on the type of contaminants and/or wastewater matrix. Copyright © 2017 Elsevier Ltd. All rights reserved.

Off-axis dose equivalent due to secondary neutrons from uniform scanning proton beams during proton radiotherapy

NASA Astrophysics Data System (ADS)

Islam, M. R.; Collums, T. L.; Zheng, Y.; Monson, J.; Benton, E. R.

2013-11-01

The production of secondary neutrons is an undesirable byproduct of proton therapy and it is important to quantify the contribution from secondary neutrons to patient dose received outside the treatment volume. The purpose of this study is to investigate the off-axis dose equivalent from secondary neutrons experimentally using CR-39 plastic nuclear track detectors (PNTD) at ProCure Proton Therapy Center, Oklahoma City, OK. In this experiment, we placed several layers of CR-39 PNTD laterally outside the treatment volume inside a phantom and in air at various depths and angles with respect to the primary beam axis. Three different proton beams with max energies of 78, 162 and 226 MeV and 4 cm modulation width, a 5 cm diameter brass aperture, and a small snout located 38 cm from isocenter were used for the entire experiment. Monte Carlo simulations were also performed based on the experimental setup using a simplified snout configuration and the FLUKA Monte Carlo radiation transport code. The measured ratio of secondary neutron dose equivalent to therapeutic primary proton dose (H/D) ranged from 0.3 ± 0.08 mSv Gy-1 for 78 MeV proton beam to 37.4 ± 2.42 mSv Gy-1 for 226 MeV proton beam. Both experiment and simulation showed a similar decreasing trend in dose equivalent with distance to the central axis and the magnitude varied by a factor of about 2 in most locations. H/D was found to increase as the energy of the primary proton beam increased and higher H/D was observed at 135° compared to 45° and 90°. The overall higher H/D in air indicates the predominance of external neutrons produced in the nozzle rather than inside the body.

Characterization of the Radiation Shielding Properties of US andRussian EVA Suits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benton, E.R.; Benton, E.V.; Frank, A.L.

2001-10-26

Reported herein are results from the Eril Research, Inc.(ERI) participationin the NASA Johnson Space Center sponsored studycharacterizing the radiation shielding properties of the two types ofspace suit that astronauts are wearing during the EVA on-orbit assemblyof the International Space Station (ISS). Measurements using passivedetectors were carried out to assess the shielding properties of the USEMU Suit and the Russian Orlan-M suit during irradiations of the suitsand a tissue equivalent phantom to monoenergetic proton and electronbeams at the Loma Linda University Medical Center (LLUMC). Duringirradiations of 6 MeV electrons and 60 MeV protons, absorbed dose as afunction of depth was measuredmore » using TLDs exposed behind swatches of thetwo suit materials and inside the two EVA helmets. Considerable reductionin electron dosewas measured behind all suit materials in exposures to 6MeV electrons. Slowing of the proton beam in the suit materials led to anincrease in dose measured in exposures to 60 MeV protons. During 232 MeVproton irradiations, measurements were made with TLDs and CR-39 PNTDs atfive organ locations inside a tissue equivalent phantom, exposed bothwith and without the two EVA suits. The EVA helmets produce a 13 to 27percent reduction in total dose and a 0 to 25 percent reduction in doseequivalent when compared to measurements made in the phantom head alone.Differences in dose and dose equivalent between the suit and non-suitirradiations forthe lower portions of the two EVA suits tended to besmaller. Proton-induced target fragmentation was found to be asignificant source of increased dose equivalent, especially within thetwo EVA helmets, and average quality factor inside the EMU and Orlan-Mhelmets was 2 to 14 percent greater than that measured in the barephantom head.« less

A randomized, double-blind, active control, multicenter, dose-finding study of lipegfilgrastim (XM22) in breast cancer patients receiving myelosuppressive therapy.

PubMed

Buchner, Anton; Elsässer, Reiner; Bias, Peter

2014-11-01

This dose-ranging study was conducted to identify the optimal fixed dose of lipegfilgrastim compared with pegfilgrastim 6.0 mg for the provision of neutrophil support during myelosuppressive chemotherapy in patients with breast cancer. A phase 2 study was conducted in which 208 chemotherapy-naive patients were randomized to receive lipegfilgrastim 3.0, 4.5, or 6.0 mg or pegfilgrastim 6.0 mg. Study drugs were administered as a single subcutaneous injection on day 2 of each chemotherapy cycle (doxorubicin/docetaxel on day 1 for four 3-week cycles). The primary outcome measure was duration of severe neutropenia (DSN) in cycle 1. Patients treated with lipegfilgrastim experienced shorter DSN in cycle 1 with higher doses. The mean DSN was 0.76 days in the lipegfilgrastim 6.0-mg group and 0.87 days in the pegfilgrastim 6.0-mg group, with no significant differences between treatment groups. Treatment with lipegfilgrastim 6.0 mg was consistently associated with a higher absolute neutrophil count (ANC) at nadir, shorter ANC recovery time, and a similar safety and tolerability profile compared with pegfilgrastim. This phase 2 study demonstrated that lipegfilgrastim 6.0 mg is the optimal dose for patients with breast cancer and provides neutrophil support that is at least equivalent to the standard 6.0-mg fixed dose of pegfilgrastim.

Comparative plasma salicylate and urine salicylurate levels following administration of aspirin, magnesium salicylate, and choline magnesium trisalicylate.

PubMed

Mason, W D

1980-11-01

Eighteen healthy volunteers were administered single doses of commercially available solid dosage forms of aspirin, magnesium salicylate (I), and choline magnesium trisalicylate (II), equivalent to approximately 500 mg of salicylic acid, in a randomized, complete crossover design. Plasma salicylate and urine salicylurate levels were measured by high-pressure liquid chromatography at frequent intervals following dosing; the resultant profiles, areas under the curve (AUC), and percentages of dose excreted as salicylurate were statistically analyzed by an analysis of variance. The plasma salicylate levels following the two dosage forms containing I and II were virtually identical when corrected for small differences in the dose. The plasma salicylic acid level following aspirin was approximately 10% lower during the 1.5--3.0-hr interval due to a portion of unhydrolyzed aspirin, but the dose-corrected AUC for the products tested did not differ significantly (p < 0.05). During the 24 hr following dosing, 66.5 +/- 12.1 68.4 +/- 7.1, and 60.9 +/- 14.1% of the salicylic acid were excreted as urine salicylurate for aspirin, I, and II, respectively, with no significant difference (p < 0.05). Based on this study, there are no significant differences in the rate and extent of absorption of salicylate following the three dosage forms tested, and the elimination kinetics of salicylic acid are not altered by these dosage forms.

Assessment of normal tissue complications following prostate cancer irradiation: Comparison of radiation treatment modalities using NTCP models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takam, Rungdham; Bezak, Eva; Yeoh, Eric E.

2010-09-15

Purpose: Normal tissue complication probability (NTCP) of the rectum, bladder, urethra, and femoral heads following several techniques for radiation treatment of prostate cancer were evaluated applying the relative seriality and Lyman models. Methods: Model parameters from literature were used in this evaluation. The treatment techniques included external (standard fractionated, hypofractionated, and dose-escalated) three-dimensional conformal radiotherapy (3D-CRT), low-dose-rate (LDR) brachytherapy (I-125 seeds), and high-dose-rate (HDR) brachytherapy (Ir-192 source). Dose-volume histograms (DVHs) of the rectum, bladder, and urethra retrieved from corresponding treatment planning systems were converted to biological effective dose-based and equivalent dose-based DVHs, respectively, in order to account for differences inmore » radiation treatment modality and fractionation schedule. Results: Results indicated that with hypofractionated 3D-CRT (20 fractions of 2.75 Gy/fraction delivered five times/week to total dose of 55 Gy), NTCP of the rectum, bladder, and urethra were less than those for standard fractionated 3D-CRT using a four-field technique (32 fractions of 2 Gy/fraction delivered five times/week to total dose of 64 Gy) and dose-escalated 3D-CRT. Rectal and bladder NTCPs (5.2% and 6.6%, respectively) following the dose-escalated four-field 3D-CRT (2 Gy/fraction to total dose of 74 Gy) were the highest among analyzed treatment techniques. The average NTCP for the rectum and urethra were 0.6% and 24.7% for LDR-BT and 0.5% and 11.2% for HDR-BT. Conclusions: Although brachytherapy techniques resulted in delivering larger equivalent doses to normal tissues, the corresponding NTCPs were lower than those of external beam techniques other than the urethra because of much smaller volumes irradiated to higher doses. Among analyzed normal tissues, the femoral heads were found to have the lowest probability of complications as most of their volume was irradiated to lower equivalent doses compared to other tissues.« less

Utility of Japanese encephalitis virus subgenomic replicon-based single-round infectious particles as antigens in neutralization tests for Zika virus and three other flaviviruses.

PubMed

Yamanaka, Atsushi; Moi, Meng Ling; Takasaki, Tomohiko; Kurane, Ichiro; Matsuda, Mami; Suzuki, Ryosuke; Konishi, Eiji

2017-05-01

The introduction of a foreign virus into an area may cause an outbreak, as with the Zika virus (ZIKV) outbreak in the Americas. Preparedness for handling a viral outbreak involves the development of tests for the serodiagnosis of foreign virus infections. We previously established a gene-based technology to generate some flaviviral antigens useful for functional antibody assays. The technology utilizes a Japanese encephalitis virus subgenomic replicon to generate single-round infectious particles (SRIPs) that possess designed surface antigens. In the present study, we successfully expanded the capacity of SRIPs to four human-pathogenic mosquito-borne flaviviruses that could potentially be introduced from endemic to non-endemic countries: ZIKV, Sepik virus, Wesselsbron virus, and Usutu virus. Flavivirus-crossreactive monoclonal antibodies dose-dependently neutralized these SRIPs. ZIKV-SRIPs also produced antibody-dose-dependent neutralization curves equivalent to those shown by authentic ZIKV particles using sera from a Zika fever patient. The faithful expression of designed surface antigens on SRIPs will allow their use in neutralization tests to diagnose foreign flaviviral infections. Copyright © 2017 Elsevier B.V. All rights reserved.

The systemic exposure to inhaled beclometasone/formoterol pMDI with valved holding chamber is independent of age and body size.

PubMed

Govoni, Mirco; Piccinno, Annalisa; Lucci, Germano; Poli, Gianluigi; Acerbi, Daniela; Baronio, Roberta; Singh, Dave; Kuna, Piotr; Chawes, Bo L K; Bisgaard, Hans

2015-02-01

Asthma guidelines recommend prescription of inhaled corticosteroids at a reduced dosage in children compared to older patients in order to minimize the systemic exposure and risk of unwanted side effects. In children, pressurized metered dose inhalers (pMDI) are recommended in combination with a valved holding chamber (VHC) to overcome the problem of coordinating inhalation with actuation. However, the influence of age and body size on the systemic exposure of drugs to be administered via a pMDI with VHC is still not fully elucidated. Therefore, we aimed to compare the systemic exposure to the active ingredients of a fixed combination of beclometasone-dipropionate/formoterol-fumarate administered via pMDI with VHC in children, adolescents and adults. The pharmacokinetics of formoterol and beclometasone-17-monopropionate (active metabolite of beclometasone-dipropionate) was evaluated over 8 h from three studies, each performed in a different age and body size group. Children (7-11 years, n = 20), adolescents (12-17 years, n = 29) and adults (≥18 years, n = 24) received a single dose of beclometasone/formoterol (children: 200 μg/24 μg, adolescents and adults: 400 μg/24 μg) via pMDI with AeroChamber Plus™. The systemic exposure in children in comparison to adolescents was equivalent for formoterol while it was halved for beclometasone-17-monopropionate in accordance with the halved dose of beclometasone administered in children (90% CIs within 0.8-1.25 for formoterol and 0.4-0.625 for beclometasone-17-monopropionate). The systemic exposure to beclometasone-17-monopropionate and formoterol was equivalent between adolescents and adults. The systemic exposure to the active ingredients of a fixed dose combination of beclometasone/formoterol administered via pMDI with AeroChamber Plus™ correlates with the nominal dose independently of patient age and body size. Thus, dose reduction in relation to age when using a pMDI with VHC may be unnecessary for reducing the systemic exposure in children. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dose ratio proton radiography using the proximal side of the Bragg peak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doolan, P. J., E-mail: paul.doolan.09@ucl.ac.uk; Royle, G.; Gibson, A.

Purpose: In recent years, there has been a movement toward single-detector proton radiography, due to its potential ease of implementation within the clinical environment. One such single-detector technique is the dose ratio method in which the dose maps from two pristine Bragg peaks are recorded beyond the patient. To date, this has only been investigated on the distal side of the lower energy Bragg peak, due to the sharp falloff. The authors investigate the limits and applicability of the dose ratio method on the proximal side of the lower energy Bragg peak, which has the potential to allow a muchmore » wider range of water-equivalent thicknesses (WET) to be imaged. Comparisons are made with the use of the distal side of the Bragg peak. Methods: Using the analytical approximation for the Bragg peak, the authors generated theoretical dose ratio curves for a range of energy pairs, and then determined how an uncertainty in the dose ratio would translate to a spread in the WET estimate. By defining this spread as the accuracy one could achieve in the WET estimate, the authors were able to generate lookup graphs of the range on the proximal side of the Bragg peak that one could reliably use. These were dependent on the energy pair, noise level in the dose ratio image and the required accuracy in the WET. Using these lookup graphs, the authors investigated the applicability of the technique for a range of patient treatment sites. The authors validated the theoretical approach with experimental measurements using a complementary metal oxide semiconductor active pixel sensor (CMOS APS), by imaging a small sapphire sphere in a high energy proton beam. Results: Provided the noise level in the dose ratio image was 1% or less, a larger spread of WETs could be imaged using the proximal side of the Bragg peak (max 5.31 cm) compared to the distal side (max 2.42 cm). In simulation, it was found that, for a pediatric brain, it is possible to use the technique to image a region with a square field equivalent size of 7.6 cm{sup 2}, for a required accuracy in the WET of 3 mm and a 1% noise level in the dose ratio image. The technique showed limited applicability for other patient sites. The CMOS APS demonstrated a good accuracy, with a root-mean-square-error of 1.6 mm WET. The noise in the measured images was found to be σ = 1.2% (standard deviation) and theoretical predictions with a 1.96σ noise level showed good agreement with the measured errors. Conclusions: After validating the theoretical approach with measurements, the authors have shown that the use of the proximal side of the Bragg peak when performing dose ratio imaging is feasible, and allows for a wider dynamic range than when using the distal side. The dynamic range available increases as the demand on the accuracy of the WET decreases. The technique can only be applied to clinical sites with small maximum WETs such as for pediatric brains.« less

Effective Dose Equivalent due to Cosmic Ray Particles and Their Secondary Particles on the Moon

NASA Astrophysics Data System (ADS)

Hayatsu, Kanako; Hareyama, Makoto; Kobayashi, Shingo; Karouji, Yuzuru; Sakurai, K.; Sihver, Lembit; Hasebe, N.

Estimation of radiation dose on and under the lunar surface is quite important for human activity on the Moon and for the future lunar bases construction. Radiation environment on the Moon is much different from that on the Earth. Galactic cosmic rays (GCRs) and solar energetic particles (SEPs) directly penetrate the lunar surface because of no atmosphere and no magnetic field around the Moon. Then, they generate many secondary particles such as neutrons, gamma rays and other charged particles by nuclear interactions with soils and regolith breccias under the lunar surface. Therefore, the estimation of radiation dose from them on the surface and the underground of the Moon are essential for safety human activities. In this study, the effective dose equivalents at the surface and various depths of the Moon were estimated using by the latest cosmic rays observation and developed calculation code. The largest contribution to the dose on the surface is primary charged particles in GCRs and SEPs, while in the ground, secondary neutrons are the most dominant. In particular, the dose from neutrons becomes maximal at 70-80 g/cm2 in depth of lunar soil, because fast neutrons with about 1.0 MeV are mostly produced at this depth and give the largest dose. On the lunar surface, the doses originated from large SEPs are very hazardous. We estimated the effective dose equivalents due to such large SEPs and the effects of aluminum shield for the large flare on the human body. In the presentation, we summarize and discuss the improved calculation results of radiation doses due to GCR particles and their secondary particles in the lunar subsurface. These results will provide useful data for the future exploration of the Moon.

Depth dose measurements with the Liulin-5 experiment inside the spherical phantom of the MATROSHKA-R project onboard the International Space Station

NASA Astrophysics Data System (ADS)

Semkova, J.; Koleva, R.; Maltchev, St.; Bankov, N.; Benghin, V.; Chernykh, I.; Shurshakov, V.; Petrov, V.; Drobyshev, S.; Nikolaev, I.

2012-02-01

The Liulin-5 experiment is a part of the international project MATROSHKA-R on the Russian segment of the ISS, which uses a tissue-equivalent spherical phantom equipped with a set of radiation detectors. The objective of the MATROSHKA-R project is to provide depth dose distribution of the radiation field inside the sphere in order to get more information on the distribution of dose in a human body. Liulin-5 is a charged particle telescope using three silicon detectors. It measures time resolved energy deposition spectra, linear energy transfer (LET) spectra, particle flux, and absorbed doses of electrons, protons and heavy ions, simultaneously at three depths along the radius of the phantom. Measurements during the minimum of the solar activity in cycle 23 show that the average absorbed daily doses at 40 mm depth in the phantom are between 180 μGy/day and 220 μGy/day. The absorbed doses at 165 mm depth in the phantom decrease by a factor of 1.6-1.8 compared to the doses at 40 mm depth due to the self-shielding of the phantom from trapped protons. The average dose equivalent at 40 mm depth is 590 ± 32 μSV/day and the galactic cosmic rays (GCR) contribute at least 70% of the total dose equivalent at that depth. Shown is that due to the South Atlantic Anomaly (SAA) trapped protons asymmetry and the direction of Liulin-5 lowest shielding zone the dose rates on ascending and descending nodes in SAA are different. The data obtained are compared to data from other radiation detectors on ISS.

Experimental verification of a Monte Carlo-based MLC simulation model for IMRT dose calculations in heterogeneous media

NASA Astrophysics Data System (ADS)

Tyagi, N.; Curran, B. H.; Roberson, P. L.; Moran, J. M.; Acosta, E.; Fraass, B. A.

2008-02-01

IMRT often requires delivering small fields which may suffer from electronic disequilibrium effects. The presence of heterogeneities, particularly low-density tissues in patients, complicates such situations. In this study, we report on verification of the DPM MC code for IMRT treatment planning in heterogeneous media, using a previously developed model of the Varian 120-leaf MLC. The purpose of this study is twofold: (a) design a comprehensive list of experiments in heterogeneous media for verification of any dose calculation algorithm and (b) verify our MLC model in these heterogeneous type geometries that mimic an actual patient geometry for IMRT treatment. The measurements have been done using an IMRT head and neck phantom (CIRS phantom) and slab phantom geometries. Verification of the MLC model has been carried out using point doses measured with an A14 slim line (SL) ion chamber inside a tissue-equivalent and a bone-equivalent material using the CIRS phantom. Planar doses using lung and bone equivalent slabs have been measured and compared using EDR films (Kodak, Rochester, NY).

Protective efficacy of Zika vaccine in AG129 mouse model

PubMed Central

Sumathy, K.; Kulkarni, Bharathi; Gondu, Ravi Kumar; Ponnuru, Sampath Kumar; Bonguram, Nagaraju; Eligeti, Rakesh; Gadiyaram, Sindhuja; Praturi, Usha; Chougule, Bhushan; Karunakaran, Latha; Ella, Krishna M.

2017-01-01

Zika virus (ZIKV) is a mosquito-borne flavivirus that causes asymptomatic infection or presents only mild symptoms in majority of those infected. However, vaccination for ZIKV is a public health priority due to serious congenital and neuropathological abnormalities observed as a sequelae of the virus infection in the recent epidemics. We have developed an inactivated virus vaccine with the African MR 766 strain. Here we show that two doses of the vaccine provided 100% efficacy against mortality and disease following challenge with homotypic MR 766 and the heterotypic FSS 13025 ZIKV strains in the Type I and Type II interferon deficient AG129 mice. Two doses of the vaccine elicited high titer of neutralizing antibodies in Balb/c mice, and the vaccine antisera conferred protection against virus challenge in passively immunized mice. The studies were useful to rationalize vaccine doses for protective efficacy. Furthermore, the vaccine antisera neutralized the homotypic and heterotypic ZIKV strains in vitro with equivalent efficiency. Our study suggests a single ZIKV serotype, and that the development of an effective vaccine may not be limited by the choice of virus strain. PMID:28401907

Protective efficacy of Zika vaccine in AG129 mouse model.

PubMed

Sumathy, K; Kulkarni, Bharathi; Gondu, Ravi Kumar; Ponnuru, Sampath Kumar; Bonguram, Nagaraju; Eligeti, Rakesh; Gadiyaram, Sindhuja; Praturi, Usha; Chougule, Bhushan; Karunakaran, Latha; Ella, Krishna M

2017-04-12

Zika virus (ZIKV) is a mosquito-borne flavivirus that causes asymptomatic infection or presents only mild symptoms in majority of those infected. However, vaccination for ZIKV is a public health priority due to serious congenital and neuropathological abnormalities observed as a sequelae of the virus infection in the recent epidemics. We have developed an inactivated virus vaccine with the African MR 766 strain. Here we show that two doses of the vaccine provided 100% efficacy against mortality and disease following challenge with homotypic MR 766 and the heterotypic FSS 13025 ZIKV strains in the Type I and Type II interferon deficient AG129 mice. Two doses of the vaccine elicited high titer of neutralizing antibodies in Balb/c mice, and the vaccine antisera conferred protection against virus challenge in passively immunized mice. The studies were useful to rationalize vaccine doses for protective efficacy. Furthermore, the vaccine antisera neutralized the homotypic and heterotypic ZIKV strains in vitro with equivalent efficiency. Our study suggests a single ZIKV serotype, and that the development of an effective vaccine may not be limited by the choice of virus strain.