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Sample records for skin dose equivalent

  1. Interplanetary crew doses and dose equivalents: variations among different bone marrow and skin sites

    NASA Astrophysics Data System (ADS)

    Hoff, J. L.; Townsend, L. W.; Zapp, E. N.

    2004-01-01

    Previously, calculations of bone marrow dose from the large solar particle event (SPE) of July 2000 were carried out using the BRYNTRN space radiation transport code and the computerized anatomical man (CAM) model. Results indicated that the dose for a bone marrow site in the mid-thigh might be twice as large as the dose for a site in the pelvis. These large variations may be significant for space radiation protection purposes, which traditionally use an average of many (typically 33) sites throughout the body. Other organs that cover large portions of the body, such as the skin, may also exhibit similar variations with doses differing from site to site. The skin traditionally uses an average of 32 sites throughout the body. Variations also occur from site to site among the dose equivalents, which may be important in determining stochastic effects. In this work, the magnitudes of dose and dose equivalent variations from site to site are investigated. The BRYNTRN and HZETRN transport codes and the CAM model are used to estimate bone marrow and skin doses and dose equivalents as a function of position in the body for several large solar particle events and annual galactic cosmic ray spectra from throughout the space era. These position-specific results are compared with the average values usually used for radiation protection purposes. Various thicknesses of aluminum shielding, representative of nominal spacecraft, are used in the analyses.

  2. Interplanetary Crew Doses and Dose Equivalents: Variations among Different Bone Marrow and Skin Sites

    NASA Astrophysics Data System (ADS)

    Hoff, J.; Townsend, L.; Zapp, E.

    Previously, calculations of bone marrow dose from the large solar particle event (SPE) of July 2000 were carried out using the BRYNTRN space radiation transport code and the Computerized Anatomical Man (CAM) model. Results indicated that the dose for a bone marrow site in the mid-thigh might be twice as large as the dose for a site in the pelvis. These large variations may be significant for space radiation protection purposes, which traditionally use an average of many (typically 33) sites throughout the body. Other organs that cover large portions of the body, such as the skin, may also exhibit similar variations with doses differing from site to site. The skin traditionally uses an average of 32 sites throughout the body. Variations also occur from site to site among the dose equivalents, which may be important in determining stochastic effects. In this work, the magnitudes of dose and dose equivalent variations from site to site are investigated. The BRYNTRN and HZETRN transport codes and the CAM model are used to estimate bone marrow and skin doses and dose equivalents as a function of position in the body for several large solar particle events and annual galactic cosmic ray (GCR) spectra from throughout the space era. These position-specific results are compared with the average values usually used for radiation protection purposes. Various thicknesses of aluminum shielding, representative of nominal spacecraft and SPE "storm shelter" designs, are used in the analyses.

  3. 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.

  4. Tissue Engineered Human Skin Equivalents

    PubMed Central

    Zhang, Zheng; Michniak-Kohn, Bozena B.

    2012-01-01

    Human skin not only serves as an important barrier against the penetration of exogenous substances into the body, but also provides a potential avenue for the transport of functional active drugs/reagents/ingredients into the skin (topical delivery) and/or the body (transdermal delivery). In the past three decades, research and development in human skin equivalents have advanced in parallel with those in tissue engineering and regenerative medicine. The human skin equivalents are used commercially as clinical skin substitutes and as models for permeation and toxicity screening. Several academic laboratories have developed their own human skin equivalent models and applied these models for studying skin permeation, corrosivity and irritation, compound toxicity, biochemistry, metabolism and cellular pharmacology. Various aspects of the state of the art of human skin equivalents are reviewed and discussed. PMID:24300178

  5. Psychotropic dose equivalence in Japan.

    PubMed

    Inada, Toshiya; Inagaki, Ataru

    2015-08-01

    Psychotropic dose equivalence is an important concept when estimating the approximate psychotropic doses patients receive, and deciding on the approximate titration dose when switching from one psychotropic agent to another. It is also useful from a research viewpoint when defining and extracting specific subgroups of subjects. Unification of various agents into a single standard agent facilitates easier analytical comparisons. On the basis of differences in psychopharmacological prescription features, those of available psychotropic agents and their approved doses, and racial differences between Japan and other countries, psychotropic dose equivalency tables designed specifically for Japanese patients have been widely used in Japan since 1998. Here we introduce dose equivalency tables for: (i) antipsychotics; (ii) antiparkinsonian agents; (iii) antidepressants; and (iv) anxiolytics, sedatives and hypnotics available in Japan. Equivalent doses for the therapeutic effects of individual psychotropic compounds were determined principally on the basis of randomized controlled trials conducted in Japan and consensus among dose equivalency tables reported previously by psychopharmacological experts. As these tables are intended to merely suggest approximate standard values, physicians should use them with discretion. Updated information of psychotropic dose equivalence in Japan is available at http://www.jsprs.org/en/equivalence.tables/. [Correction added on 8 July 2015, after first online publication: A link to the updated information has been added.].

  6. 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

  7. 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.

  8. Ambient dose equivalents in TGFs

    NASA Astrophysics Data System (ADS)

    Celestin, Sebastien; Pincon, Jean-Louis; Trompier, Francois

    2017-04-01

    Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from the Earth's atmosphere in association with thunderstorm activity [e.g., Briggs et al., JGR, 118, 3805, 2013]. TGFs are associated with initial propagation stages of intracloud lightning, which represent the most frequent type of lightning discharges [e.g., Cummer et al., GRL, 42, 7792, 2015, and references therein]. TGFs are known to be produced inside common thunderclouds [e.g., Splitt et al., JGR, 115, A00E38, 2010] typically at altitudes ranging from 10 to 14 km [e.g., Cummer et al., GRL, 41, 8586, 2014]. The global TGF occurrence rate is estimated to be 400,000 per year concerning TGFs detectable by Fermi-GBM (Gamma ray Burst Monitor) [Briggs et al., 2013], but detailed analysis of satellite measurements [Østgaard et al., JGR, 117, A03327, 2012] and theoretical studies [Celestin et al., JGR, 120, 10712, 2015] suggest that it cannot be excluded that TGFs represent a part of a regular process taking place during the propagation of lightning discharges. It is important to assess the risk induced by TGFs for airline passengers and crews on board aircraft approaching thunderstorms. Dwyer et al. [JGR, 115, D09206, 2010] have estimated that if an aircraft were to find itself in the source electron beam giving rise to a TGF, passengers and crews might receive effective radiation doses above the regulatory limit depending on the beam diameter. Moreover, Tavani et al. [Nat. Hazards Earth Syst. Sci., 13, 1127, 2013] concluded that TGF-associated neutrons produced by photonuclear reactions would cause serious hazard on the aircraft avionics. In this work, we will present detailed simulation-based estimations of effective doses received by humans that would be irradiated by TGFs for various production altitudes and distances from the TGF source.

  9. Development and Testing of Living Skin Equivalent.

    DTIC Science & Technology

    1988-05-01

    Model a) The use of Isografts in an inbred strain of rats. In a preliminary series of experiments the potential use of Fischer strain rats has been...tested by preparing a series of isografts made by grafting skin equivalents with cells from female donors to male hosts. On the average, wound...Autograft--rat 4 1 4 3 5 17 Autograft--rabbit 6 3 1 1 11 Isograft --rat 37 13 13 1 64 Allo fib., iso ker--rat 15 12 3 30 Allo fib, iso ker--rab 8 6 14 Iso

  10. Structural analysis of artificial skin equivalents

    NASA Astrophysics Data System (ADS)

    Schmitt, Robert; Marx, Ulrich; Walles, Heike; Schober, Lena

    2011-06-01

    Artificial skin equivalents ASEs based on primary fibroblasts and keratinocytes show a high batch variance in their structural and morphological characteristics. Due to biological fluctuations and variable donor age, the growth processes of 3D tissue structure show a non constant quality. Since theses ASEs are used as testing system for chemicals, pharmaceuticals or cosmetics it is of major interest to know detailed and significant characteristics about each individual ASE. Until now, the microscopic analysis process is based on the destructive preparation of histologies allowing only the characterization on a random basis. In this study we present analytical methods to characterise each individual ASE by Optical Coherence Tomography OCT in combination with image processing tools. Therefore, we developed a fully automated OCT device, that performs automatic measurements of microtiter plates MTPs holing the ASEs in a sterile environment. We developed image processing algorithms to characterize the surface structure which may function as an indicator for defects in the epidermal stratum corneum. Further, we analysed the tomographic morphological structure of the ASEs. The results show, that variances in the growth state as well different collagen formation is detectable. In combination with dynamic threshold levels, we found, that OCT is a well suited technology for automatically characterizing artificial skin equivalents and may partly substitute the preparation of histologies.

  11. Dioxin equivalency: Challenge to dose extrapolation

    SciTech Connect

    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 had 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.

  12. 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.

  13. Skin equivalents: skin from reconstructions as models to study skin development and diseases.

    PubMed

    Ali, N; Hosseini, M; Vainio, S; Taïeb, A; Cario-André, M; Rezvani, H R

    2015-08-01

    While skin is readily available for sampling and direct studies of its constituents, an important intermediate step is to design in vitro and/or in vivo models to address scientific or medical questions in dermatology and skin biology. Pioneered more than 30 years ago, human skin equivalents (HSEs) have been refined with better cell culture techniques and media, together with sophisticated cell biology tools including genetic engineering and cell reprogramming. HSEs mimic key elements of human skin biology and have been instrumental in demonstrating the importance of cell-cell interactions in skin homeostasis and the role of a complex cellular microenvironment to coordinate epidermal proliferation, differentiation and pigmentation. HSEs have a wide field of applications from cell biology to dermocosmetics, modelling diseases, drug development, skin ageing, pathophysiology and regenerative medicine. In this article we critically review the major current approaches used to reconstruct organotypic skin models and their application with a particular emphasis on skin biology and pathophysiology of skin disorders. © 2015 British Association of Dermatologists.

  14. 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.

  15. Assessment of the effective dose equivalent for external photon radiation

    SciTech Connect

    Reece, W.D.; Poston, J.W.; Xu, X.G. )

    1993-02-01

    Beginning in January 1994, US nuclear power plants must change the way that they determine the radiation exposure to their workforce. At that time, revisions to Title 10 Part 20 of the Code of Federal Regulations will be in force requiring licensees to evaluate worker radiation exposure using a risk-based methodology termed the effective dose equivalent.'' A research project was undertaken to improve upon the conservative method presently used for assessing effective dose equivalent. In this project effective dose equivalent was calculated using a mathematical model of the human body, and tracking photon interactions for a wide variety of radiation source geometries using Monte Carlo computer code simulations. Algorithms were then developed to relate measurements of the photon flux on the surface of the body (as measured by dosimeters) to effective dose equivalent. This report (Volume I of a two-part study) describes: the concept of effective dose equivalent, the evolution of the concept and its incorporation into regulations, the variations in human organ susceptibility to radiation, the mathematical modeling and calculational techniques used, the results of effective dose equivalent calculations for a broad range of photon energiesand radiation source geometries. The study determined that for beam radiation sources the highest effective dose equivalent occurs for beams striking the front of the torso. Beams striking the rear of the torsoproduce the next highest effective dose equivalent, with effective dose equivalent falling significantly as one departs from these two orientations. For point sources, the highest effective dose equivalent occurs when the sources are in contact with the body on the front of the torso. For females the highest effective dose equivalent occurs when the source is on the sternum, for males when it is on the gonads.

  16. Neutron detector simultaneously measures fluence and dose equivalent

    NASA Technical Reports Server (NTRS)

    Dvorak, R. F.; Dyer, N. C.

    1967-01-01

    Neutron detector acts as both an area monitoring instrument and a criticality dosimeter by simultaneously measuring dose equivalent and fluence. The fluence is determined by activation of six foils one inch below the surface of the moderator. Dose equivalent is determined from activation of three interlocked foils at the center of the moderator.

  17. Red bone marrow doses, integral absorbed doses, and somatically effective dose equivalent from four maxillary occlusal projections

    SciTech Connect

    Berge, T.I.; Wohni, T.

    1984-02-01

    Phantom measurements of red bone marrow (RBM) doses, integral absorbed doses, and somatically effective dose equivalent (SEDE) from four different maxillary occlusal projections are presented. For each projection, different combinations of focus-skin distances and tube potentials were compared with regard to the patient's radiation load. The axial incisal view produced the highest patient exposures, with a maximum red bone marrow dose of 122.5 microGy/exposure, integral absorbed dose of 8.6 mJ/exposure, and SEDE values of 39.6 microSv/exposure. The corresponding values from the frontal, lateral occlusal, and tuber views ranged between 4% and 44% of the axial incisal view values for the integral absorbed dose and SEDE values, and between 0.3% and 3% for the red bone marrow doses. Increasing the focus-skin distance from 17.5 cm to 27 cm is accompanied by a 24% to 30% reduction in integral absorbed dose. Increasing the tube potential from 50 kV to 65 kV likewise results in a 23% reduction in absorbed energy.

  18. Chlorpromazine equivalent doses for the newer atypical antipsychotics.

    PubMed

    Woods, Scott W

    2003-06-01

    Several clinical and research applications require an estimation of therapeutic dose equivalence across antipsychotic medications. Since the advent of the newer atypical antipsychotics, new dose equivalent estimations have been needed. The reported minimum effective dose was identified for each newer atypical antipsychotic medication and for haloperidol across all available fixed-dose placebo-controlled studies. Reported minimum effective dose equivalence ratios to haloperidol were then converted to chlorpromazine equivalents using the "2 mg of haloperidol equals 100 mg of chlorpromazine" convention. To identify the fixed-dose studies, the following sources were searched until June 2002: MEDLINE, the bibliographies of identified reports, published meta-analyses and reviews, Cochrane reviews, Freedom of Information Act material available from the Food and Drug Administration, and abstracts from several scientific meetings from 1997 to 2002. Doses equivalent to 100 mg/day of chlorpromazine were 2 mg/day for risperidone, 5 mg/day for olanzapine, 75 mg/day for quetiapine, 60 mg/day for ziprasidone, and 7.5 mg/day for aripiprazole. These equivalency estimates may be useful for clinical and research purposes. The source of the dose equivalency estimation is evidence-based and consistent across medication.

  19. 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.

  20. Skin dose measurement with MICROSPEC-2{trademark}

    SciTech Connect

    Hsu, H.H.; Chen, J.; Ing, H.; Clifford, E.T.H.; McLean, T.

    1997-10-01

    For many years, the Eberline HP-260{trademark} beta detectors were used for skin dose measurements at Los Alamos National Laboratory. This detector does not measure the beta spectrum and the skin dose can only be determined if the contaminating radioactive isotope is known. A new product MICROSPEC-2{trademark}, has been developed which consists of a small portable computer with a multichannel analyzer and a beta probe consisting of a phoswich detector. The system measures the beta spectrum and automatically folds in the beta fluence-to-dose conversion function to yield the skin dose.

  1. Keratinocytes and fibroblasts in a human skin equivalent model enhance melanocyte survival and melanin synthesis after ultraviolet irradiation.

    PubMed

    Archambault, M; Yaar, M; Gilchrest, B A

    1995-05-01

    To investigate paracrine effects of fibroblasts and keratinocytes on melanocyte behavior after ultraviolet (UV) irradiation, we compared an in vitro skin equivalent model with melanocyte cultures. Human melanocytes were maintained alone in monolayer cultures or on dermal equivalents with or without keratinocytes and were irradiated daily with solar-simulated light. After seven daily UV irradiations, monolayer melanocytes displayed dose-dependent increases in cellular damage. In contrast, melanocytes on dermal equivalents survived strikingly better. Moreover, UV-irradiated skin equivalent melanocytes became highly dendritic as compared with sham-irradiated cells, closely mimicking their morphology in UV-irradiated skin. In addition, in skin equivalents melanocytes migrated from the center to the periphery of the keratinocyte layer after UV irradiation. Melanin production per culture, as measured by 14C-dihydroxyphenylalanine incorporation, was consistently higher in skin equivalent melanocytes than in monolayer melanocytes from the same donor, and it was highest in melanocytes from skin equivalents containing both keratinocytes and fibroblasts. Our data strongly suggest that fibroblasts and keratinocytes modulate melanocyte function in skin. The skin equivalent is a valuable model for investigating paracrine effects on melanocytes after UV irradiation.

  2. 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).

  3. Equivalent models of corrugated laminates for morphing skins

    NASA Astrophysics Data System (ADS)

    Xia, Yuying; Friswell, Michael I.

    2011-03-01

    The design of the skins has been identified as a major issue for morphing aircraft wings. Corrugated laminates provide a good solution due to their extremely anisotropic behavior. However, the optimal design of a morphing aircraft requires simple models of the skins that may be incorporated into multi-disciplinary system models. This requires equivalent material models that retain the dependence on the geometric parameters of the corrugated skins. An analytical homogenization model, which could be used for any corrugation shape, is suggested in this paper. This method is based on a simplified geometry for a unit-cell and the stiffness properties of original sheet. This paper investigates such a modeling strategy and demonstrates its performance and potential.

  4. Human skin equivalent as an alternative to animal testing.

    PubMed

    Mertsching, Heike; Weimer, Michaela; Kersen, Silke; Brunner, Herwig

    2008-03-11

    The 3-D skin equivalent can be viewed as physiologically comparable to the natural skin and therefore is a suitable alternative for animal testing. This highly differentiated in vitro human skin equivalent is used to assess the efficacy and mode of action of novel agents. This model is generated from primary human keratinocytes on a collagen substrate containing human dermal fibroblasts. It is grown at the air-liquid interface which allows full epidermal stratification and epidermal-dermal interactions to occur. Future emphasis is the establishment of different test systems to investigate wound healing, melanoma research and infection biology. Key features of this skin model are that it can be used as an alternative for in vivo studies, donor tissue can be tailored to the needs of the study and multiple analyses can be carried out at mRNA and protein level. Driven by both ethical and economical incentives, this has already resulted in a shift of the test strategies used by the Pharmaceutical Industry in the early drug development process as reflected by the increased demand for application of cell based assays. It is also a suitable model for testing a wide variety of endpoints including cell viability, the release of proinflammatory mediators, permeation rate, proliferation and biochemical changes.

  5. Equivalent Skin Analysis of Wing Structures Using Neural Networks

    NASA Technical Reports Server (NTRS)

    Liu, Youhua; Kapania, Rakesh K.

    2000-01-01

    An efficient method of modeling trapezoidal built-up wing structures is developed by coupling. in an indirect way, an Equivalent Plate Analysis (EPA) with Neural Networks (NN). Being assumed to behave like a Mindlin-plate, the wing is solved using the Ritz method with Legendre polynomials employed as the trial functions. This analysis method can be made more efficient by avoiding most of the computational effort spent on calculating contributions to the stiffness and mass matrices from each spar and rib. This is accomplished by replacing the wing inner-structure with an "equivalent" material that combines to the skin and whose properties are simulated by neural networks. The constitutive matrix, which relates the stress vector to the strain vector, and the density of the equivalent material are obtained by enforcing mass and stiffness matrix equities with rec,ard to the EPA in a least-square sense. Neural networks for the material properties are trained in terms of the design variables of the wing structure. Examples show that the present method, which can be called an Equivalent Skin Analysis (ESA) of the wing structure, is more efficient than the EPA and still fairly good results can be obtained. The present ESA is very promising to be used at the early stages of wing structure design.

  6. Verification of an effective dose equivalent model for neutrons

    SciTech Connect

    Tanner, J.E.; Piper, R.K.; Leonowich, J.A.; Faust, L.G.

    1991-10-01

    Since the effective dose equivalent, based on the weighted sum of organ dose equivalents, is not a directly measurable quantity, it must be estimated with the assistance of computer modeling techniques and a knowledge of the radiation field. Although extreme accuracy is not necessary for radiation protection purposes, a few well-chosen measurements are required to confirm the theoretical models. Neutron measurements were performed in a RANDO phantom using thermoluminescent dosemeters, track etch dosemeters, and a 1/2-in. (1.27-cm) tissue equivalent proportional counter in order to estimate neutron doses and dose equivalents within the phantom at specific locations. The phantom was exposed to bare and D{sub 2}O-moderated {sup 252}Cf neutrons at the Pacific Northwest Laboratory's Low Scatter Facility. The Monte Carlo code MCNP with the MIRD-V mathematical phantom was used to model the human body and calculate organ doses and dose equivalents. The experimental methods are described and the results of the measurements are compared to the calculations. 8 refs., 3 figs., 3 tabs.

  7. Sarcoptes scabiei mites modulate gene expression in human skin equivalents.

    PubMed

    Morgan, Marjorie S; Arlian, Larry G; Markey, Michael P

    2013-01-01

    The ectoparasitic mite, Sarcoptes scabiei that burrows in the epidermis of mammalian skin has a long co-evolution with its hosts. Phenotypic studies show that the mites have the ability to modulate cytokine secretion and expression of cell adhesion molecules in cells of the skin and other cells of the innate and adaptive immune systems that may assist the mites to survive in the skin. The purpose of this study was to identify genes in keratinocytes and fibroblasts in human skin equivalents (HSEs) that changed expression in response to the burrowing of live scabies mites. Overall, of the more than 25,800 genes measured, 189 genes were up-regulated >2-fold in response to scabies mite burrowing while 152 genes were down-regulated to the same degree. HSEs differentially expressed large numbers of genes that were related to host protective responses including those involved in immune response, defense response, cytokine activity, taxis, response to other organisms, and cell adhesion. Genes for the expression of interleukin-1α (IL-1α) precursor, IL-1β, granulocyte/macrophage-colony stimulating factor (GM-CSF) precursor, and G-CSF precursor were up-regulated 2.8- to 7.4-fold, paralleling cytokine secretion profiles. A large number of genes involved in epithelium development and keratinization were also differentially expressed in response to live scabies mites. Thus, these skin cells are directly responding as expected in an inflammatory response to products of the mites and the disruption of the skin's protective barrier caused by burrowing. This suggests that in vivo the interplay among these skin cells and other cell types, including Langerhans cells, dendritic cells, lymphocytes and endothelial cells, is responsible for depressing the host's protective response allowing these mites to survive in the skin.

  8. Sarcoptes scabiei Mites Modulate Gene Expression in Human Skin Equivalents

    PubMed Central

    Morgan, Marjorie S.; Arlian, Larry G.; Markey, Michael P.

    2013-01-01

    The ectoparasitic mite, Sarcoptes scabiei that burrows in the epidermis of mammalian skin has a long co-evolution with its hosts. Phenotypic studies show that the mites have the ability to modulate cytokine secretion and expression of cell adhesion molecules in cells of the skin and other cells of the innate and adaptive immune systems that may assist the mites to survive in the skin. The purpose of this study was to identify genes in keratinocytes and fibroblasts in human skin equivalents (HSEs) that changed expression in response to the burrowing of live scabies mites. Overall, of the more than 25,800 genes measured, 189 genes were up-regulated >2-fold in response to scabies mite burrowing while 152 genes were down-regulated to the same degree. HSEs differentially expressed large numbers of genes that were related to host protective responses including those involved in immune response, defense response, cytokine activity, taxis, response to other organisms, and cell adhesion. Genes for the expression of interleukin-1α (IL-1α) precursor, IL-1β, granulocyte/macrophage-colony stimulating factor (GM-CSF) precursor, and G-CSF precursor were up-regulated 2.8- to 7.4-fold, paralleling cytokine secretion profiles. A large number of genes involved in epithelium development and keratinization were also differentially expressed in response to live scabies mites. Thus, these skin cells are directly responding as expected in an inflammatory response to products of the mites and the disruption of the skin’s protective barrier caused by burrowing. This suggests that in vivo the interplay among these skin cells and other cell types, including Langerhans cells, dendritic cells, lymphocytes and endothelial cells, is responsible for depressing the host’s protective response allowing these mites to survive in the skin. PMID:23940705

  9. 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

  10. Validation of artificial skin equivalents as in vitro testing systems

    NASA Astrophysics Data System (ADS)

    Schmitt, Robert; Marx, Ulrich; Walles, Heike; Schober, Lena

    2011-03-01

    With the increasing complexity of the chemical composition of pharmaceuticals, cosmetics and everyday substances, the awareness of potential health issues and long term damages for humanoid organs is shifting into focus. Artificial in vitro testing systems play an important role in providing reliable test conditions and replacing precarious animal testing. Especially artificial skin equivalents ASEs are used for a broad spectrum of studies like penetration, irritation and corrosion of substances. One major challenge in tissue engineering is the qualification of each individual ASE as in vitro testing system. Due to biological fluctuations, the stratum corneum hornified layer of some ASEs may not fully develop or other defects might occur. For monitoring these effects we developed an fully automated Optical Coherence Tomography device. Here, we present different methods to characterize and evaluate the quality of the ASEs based on image and data processing of OCT B-scans. By analysing the surface structure, defects, like cuts or tears, are detectable. A further indicator for the quality of the ASE is the morphology of the tissue. This allows to determine if the skin model has reached the final growth state. We found, that OCT is a well suited technology for automatically characterizing artificial skin equivalents and validating the application as testing system.

  11. Radiological Dose Assessment - Nonuniform Skin Dose, Radioactive Skin Contamination, and Multiple Dosimetry

    SciTech Connect

    W. C. Inkret; M. E. Schillaci

    1999-03-01

    Radioactive skin contamination with {beta}- and {gamma}-emitting radionuclides may result in biologically significant absorbed doses to the skin. A specific exposure scenario of interest is a nonuniform skin dose delivered by {beta}- and {gamma}-emissions from radioactive skin contamination. The United States Department of Energy requires a formal evaluation and reporting of nonuniform skin doses. The United States Department of Energy also requires specific, formal procedures for evaluating the results from the placement or use of multiple dosimeters. Action levels relative to potential absorbed doses for the contamination survey instrumentation in use at Los Alamos and formal procedures for evaluating nonuniform skin doses and multiple dosimeters are developed and presented here.

  12. Pumpless microfluidic platform for drug testing on human skin equivalents

    PubMed Central

    Abaci, Hasan Erbil; Gledhill, Karl; Guo, Zongyou; Christiano, Angela M.; Shuler, Michael L.

    2014-01-01

    Advances in bio-mimetic in vitro human skin models increase the efficiency of drug screening studies. In this study, we designed and developed a microfluidic platform that allows for long-term maintenance of full thickness human skin equivalents (HSE) which are comprised of both the epidermal and dermal compartments. The design is based on the physiologically relevant blood residence times in human skin tissue and allows for the establishment of an air-epidermal interface which is crucial for maturation and terminal differentiation of HSEs. The small scale of the design reduces the amount of culture medium and the number of cells required by 36 fold compared to conventional transwell cultures. Our HSE-on-a-chip platform has the capability to recirculate the medium at desired flow rates without the need for pump or external tube connections. We demonstrate that the platform can be used to maintain HSEs for three weeks with proliferating keratinocytes similar to conventional HSE cultures. Immunohistochemistry analyses show that the differentiation and localization of keratinocytes was successfully achieved, establishing all sub-layers of the epidermis after one week. Basal keratinocytes located at the epidermal-dermal interface remain in a proliferative state for three weeks. We use a transdermal transport model to show that the skin barrier function is maintained for three weeks. We also validate the capability of the HSE-on-a-chip platform to be used for drug testing purposes by examining the toxic effects of doxorubucin on skin cells and structure. Overall, the HSE-on-a-chip is a user-friendly and cost-effective in vitro platform for drug testing of candidate molecules for skin disorders. PMID:25490891

  13. Pumpless microfluidic platform for drug testing on human skin equivalents.

    PubMed

    Abaci, Hasan Erbil; Gledhill, Karl; Guo, Zongyou; Christiano, Angela M; Shuler, Michael L

    2015-02-07

    Advances in bio-mimetic in vitro human skin models increase the efficiency of drug screening studies. In this study, we designed and developed a microfluidic platform that allows for long-term maintenance of full thickness human skin equivalents (HSE) which are comprised of both the epidermal and dermal compartments. The design is based on the physiologically relevant blood residence times in human skin tissue and allows for the establishment of an air-epidermal interface which is crucial for maturation and terminal differentiation of HSEs. The small scale of the design reduces the amount of culture medium and the number of cells required by 36 fold compared to conventional transwell cultures. Our HSE-on-a-chip platform has the capability to recirculate the medium at desired flow rates without the need for pump or external tube connections. We demonstrate that the platform can be used to maintain HSEs for three weeks with proliferating keratinocytes similar to conventional HSE cultures. Immunohistochemistry analyses show that the differentiation and localization of keratinocytes was successfully achieved, establishing all sub-layers of the epidermis after one week. Basal keratinocytes located at the epidermal-dermal interface remain in a proliferative state for three weeks. We use a transdermal transport model to show that the skin barrier function is maintained for three weeks. We also validate the capability of the HSE-on-a-chip platform to be used for drug testing purposes by examining the toxic effects of doxorubucin on skin cells and structure. Overall, the HSE-on-a-chip is a user-friendly and cost-effective in vitro platform for drug testing of candidate molecules for skin disorders.

  14. The Assessment of Effective Dose Equivalent Using Personnel Dosimeters

    NASA Astrophysics Data System (ADS)

    Xu, Xie

    From January 1994, U.S. nuclear plants must develop a technically rigorous approach for determining the effective dose equivalent for their work forces. This dissertation explains concepts associated with effective dose equivalent and describes how to assess effective dose equivalent by using conventional personnel dosimetry measurements. A Monte Carlo computer code, MCNP, was used to calculate photon transport through a model of the human body. Published mathematical phantoms of the human adult male and female were used to simulate irradiation from a variety of external radiation sources in order to calculate organ and tissue doses, as well as effective dose equivalent using weighting factors from ICRP Publication 26. The radiation sources considered were broad parallel photon beams incident on the body from 91 different angles and isotropic point sources located at 234 different locations in contact with or near the body. Monoenergetic photons of 0.08, 0.3, and 1.0 MeV were considered for both sources. Personnel dosimeters were simulated on the surface of the body and exposed to with the same sources. From these data, the influence of dosimeter position on dosimeter response was investigated. Different algorithms for assessing effective dose equivalent from personnel dosimeter responses were proposed and evaluated. The results indicate that the current single-badge approach is satisfactory for most common exposure situations encountered in nuclear plants, but additional conversion factors may be used when more accurate results become desirable. For uncommon exposures involving source situated at the back of the body or source located overhead, the current approach of using multi-badges and assigning the highest dose is overly conservative and unnecessarily expensive. For these uncommon exposures, a new algorithm, based on two dosimeters, one on the front of the body and another one on the back of the body, has been shown to yield conservative assessment of

  15. Equivalent sphere approximations for skin, eye, and blood-forming organs

    SciTech Connect

    Maxson, W.L.; Townsend, L.W.; Bier, S.G.

    1996-12-31

    Throughout the manned spaceflight program, protecting astronauts from space radiation has been the subject of intense study. For interplanetary crews, two main sources of radiation hazards are solar particle events (SPEs) and galactic cosmic rays. For nearly three decades, crew doses and related shielding requirements have been assessed using the assumption that body organ exposures are well approximated by exposures at the center of tissue-equivalent spheres. For the skin and for blood-forming organs (BFOs), these spheres have radii of 0 and 5 cm, respectively. Recent studies indicate that significant overestimation of organ doses occurs if these models are used instead of realistic human geometry models. The use of the latter, however, requires much longer computational times. In this work, the authors propose preliminary revisions to these equivalent sphere approximations that yield more realistic dose estimates.

  16. Skin dose mapping for fluoroscopically guided interventions

    PubMed Central

    Johnson, Perry B.; Borrego, David; Balter, Stephen; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E.

    2011-01-01

    Purpose: To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. Methods: In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient’s skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. Results: Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior–posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in

  17. Skin dose mapping for fluoroscopically guided interventions

    SciTech Connect

    Johnson, Perry B.; Borrego, David; Balter, Stephen; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E.

    2011-10-15

    Purpose: To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. Methods: In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient's skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. Results: Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior-posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in

  18. Inhaled corticosteroids: potency, dose equivalence and therapeutic index

    PubMed Central

    Daley-Yates, Peter T

    2015-01-01

    Glucocorticosteroids are a group of structurally related molecules that includes natural hormones and synthetic drugs with a wide range of anti-inflammatory potencies. For synthetic corticosteroid analogues it is commonly assumed that the therapeutic index cannot be improved by increasing their glucocorticoid receptor binding affinity. The validity of this assumption, particularly for inhaled corticosteroids, has not been fully explored. Inhaled corticosteroids exert their anti-inflammatory activity locally in the airways, and hence this can be dissociated from their potential to cause systemic adverse effects. The molecular structural features that increase glucocorticoid receptor binding affinity and selectivity drive topical anti-inflammatory activity. However, in addition, these structural modifications also result in physicochemical and pharmacokinetic changes that can enhance targeting to the airways and reduce systemic exposure. As a consequence, potency and therapeutic index can be correlated. However, this consideration is not reflected in asthma treatment guidelines that classify inhaled corticosteroid formulations as low-, mid- and high dose, and imbed a simple dose equivalence approach where potency is not considered to affect the therapeutic index. This article describes the relationship between potency and therapeutic index, and concludes that higher potency can potentially improve the therapeutic index. Therefore, both efficacy and safety should be considered when classifying inhaled corticosteroid regimens in terms of dose equivalence. The historical approach to dose equivalence in asthma treatment guidelines is not appropriate for the wider range of molecules, potencies and device/formulations now available. A more robust method is needed that incorporates pharmacological principles. PMID:25808113

  19. 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.

  20. Antipsychotic Dose Equivalents and Dose-Years: A Standardized Method for Comparing Exposure to Different Drugs

    PubMed Central

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

    2013-01-01

    Background 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. Methods 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. Results All comparisons to chlorpromazine and haloperidol were highly linear with R2 values greater than .9. A power transformation further improved linearity. Conclusions 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) × (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. PMID:19897178

  1. Equivalent dose rate by muons to the human body.

    PubMed

    Băcioiu, I

    2011-11-01

    In this paper, the relative sensitivity from different human tissues of the human body, at a ground level, from muon cosmic radiation has been studied. The aim of this paper was to provide information on the equivalent dose rates received from atmospheric muons to human body, at the ground level. The calculated value of the effective dose rate by atmospheric muons plus the radiation levels of the natural annual background radiation dose, at the ground level, in the momentum interval of cosmic ray muon (0.2-120.0 GeV/c) is about 2.106±0.001 mSv/y, which is insignificant in comparison with the values of the doses from the top of the atmosphere.

  2. Personal dose-equivalent conversion coefficients for 1252 radionuclides.

    PubMed

    Otto, Thomas

    2016-01-01

    Dose conversion coefficients for radionuclides are useful for routine calculations in radiation protection in industry, medicine and research. They give a simple and often sufficient estimate of dose rates during production, handling and storage of radionuclide sources, based solely on the source's activity. The latest compilation of such conversion coefficients dates from 20 y ago, based on nuclear decay data published 30 y ago. The present publication provides radionuclide-specific conversion coefficients to personal dose based on the most recent evaluations of nuclear decay data for 1252 radionuclides and fluence-to-dose-equivalent conversion coefficients for monoenergetic radiations. It contains previously unknown conversion coefficients for >400 nuclides and corrects those conversion coefficients that were based on erroneous decay schemes. For the first time, estimates for the protection quantity Hp(3) are included.

  3. On the equivalent dose for Auger electron emitters.

    PubMed

    Howell, R W; Narra, V R; Sastry, K S; Rao, D V

    1993-04-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201Tl) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET alpha particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (ICRP) provide no guidance with regard to calculating the equivalent dose for these radionuclides. The present work, using spermatogenesis in mouse testis as the experimental model, shows that the lethality of the prolific Auger emitter 125I is linearly dependent on the fraction of the radioactivity in the organ that is bound to DNA. This suggests that the equivalent dose for Auger emitters may have a similar linear dependence. Accordingly, a formalism for calculating the equivalent dose for Auger emitters is advanced within the ICRP framework.

  4. On the Equivalent Dose for Auger Electron Emitters

    PubMed Central

    Howell, Roger W.; Narra, Venkat R.; Sastry, Kandula S. R.; Rao, Dandamudi V.

    2012-01-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201T1) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET α particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (ICRP) provide no guidance with regard to calculating the equivalent dose for these radionuclides. The present work, using spermatogenesis in mouse testis as the experimental model, shows that the lethality of the prolific Auger emitter 125I is linearly dependent on the fraction of the radioactivity in the organ that is bound to DNA. This suggests that the equivalent dose for Auger emitters may have a similar linear dependence. Accordingly, a formalism for calculating the equivalent dose for Auger emitters is advanced within the ICRP framework. PMID:8475256

  5. Chlorpromazine equivalents versus defined daily doses: how to compare antipsychotic drug doses?

    PubMed

    Rijcken, Claudia A W; Monster, Taco B M; Brouwers, Jacobus R B J; de Jong-van den Berg, Lolkje T W

    2003-12-01

    Classic chlorpromazine (CPZ) equivalents can be used to chart relative antipsychotic potencies of antipsychotic drugs. Values of CPZ equivalents per drug are ambiguous in literature. In drug use evaluation studies, antipsychotic doses are frequently compared by use of the defined daily dose (DDD). The DDD is the assumed average maintenance dose per day for a drug if used for its main indication in adults. The DDD is based on review of the available older and recent literature. In this report, we evaluated discrepancy between CPZ-equivalent values and DDD-equivalent values. We plotted CPZ-equivalent values against DDD-equivalent values and performed linear regression to determine the mean relationship between the 2 methods. About 67% of the DDD-equivalent values demonstrated lower potencies for antipsychotic drug compared with CPZ-equivalent values. The slope of the regression line was 0.68 (r2 = 0.81). Because we found a great discrepancy between these 2 methods of comparing antipsychotic drug doses, we think further research is necessary to develop a standardized way of antipsychotic drug comparison.

  6. Personal Dose Equivalent Conversion Coefficients For Photons To 1 GEV

    SciTech Connect

    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, 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

  7. A portable dose equivalent meter based on microdosimetry

    NASA Astrophysics Data System (ADS)

    Braby, L. A.

    1985-05-01

    It is generally accepted that the physical basis of the relative biological effectiveness of different radiations is the difference in the spatial distribution of ionization along the charged particle tracks. Thus it is possible to measure physical quantities which may be related to biological damage, and use them to estimate the radiation protection quantity "dose equivalent". A prototype instrument utilizing a spherical proportional counter and a microcomputer to make such measurements has been developed and tested. The detector is filled with gas at low pressure in order to simulate micrometer diameter volumes of tissue. Energy deposition in these small volumes is a stochastic quantity which depends on charged particle stopping power, path length through the site, energy loss straggling, and energy transport by secondary charged particles (delta rays). It has been suggested that this energy deposition distribution be used as a basis for defining radiation quality factor ( overlineQ) [1]. However, to the extent that the energy deposition in the site is proportional to the geometric chord length distribution, energy deposition can also be used to determine the linear energy transfer. The mean quality factor can then be calculated on the basis of the current definition. The prototype instrument uses two amplifiers, with gains of 50 and 1000, processing the pulses from a single detector in order to resolve the wide range of energy deposition events produced by neutron and gamma irradiation. Each amplifier is connected to a specially designed analog to digital converter and a 128 channel multichannel analyzer. A microcomputer controls the system and calculates dose and dose equivalent. Test results for a variety of accelerator produced neutron irradiations show that, from 0.1 to 15 MeV, system accuracy is ±0.5 for overlineQ and ± 15% for dose equivalent.

  8. 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.

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

    SciTech Connect

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

    2006-07-15

    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[reg] 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.

  10. 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.

  11. Clinically relevant investigation of flattening filter-free skin dose.

    PubMed

    Guy, Christopher L; Karki, Kishor; Sharma, Manju; Kim, Siyong

    2016-11-08

    As flattening filter-free (FFF) photon beams become readily available for treat-ment delivery in techniques such as SBRT, thorough investigation of skin dose from FFF photon beams is necessary under clinically relevant conditions. Using a parallel-plate PTW Markus chamber placed in a custom water-equivalent phantom, surface-dose measurements were taken at 2 × 2, 3 × 3, 4 × 4, 6 × 6, 8 × 8, 10 × 10, 20 × 20, and 30 × 30 cm2 field sizes, at 80, 90, and 100 cm source-to-surface distances (SSDs), and with fields defined by jaws and multileaf collimator (MLC) using multiple beam energies (6X, 6XFFF, 10X, and 10XFFF). The same set of measurements was repeated with the chamber at a reference depth of 10cm. Each surface measurement was normalized by its corresponding reference depth measurement for analysis. The FFF surface doses at 100 cm SSD were higher than flattened surface doses by 45% at 2 × 2 cm2 to 13% at 20 × 20 cm2 for 6MV energy. These surface dose differences varied to a greater degree as energy increased, ranging from +63% at 2 × 2 cm2 to -2% at 20 × 20 cm2 for 10 MV. At small field sizes, higher energy increased FFF surface dose relative to flattened surface dose; while at larger field sizes, relative FFF surface dose was higher for lower energies. At both energies investigated, decreasing SSD caused a decrease in the ratios of FFF-to-flattened surface dose. Variability with SSD of FFF-to-flattened surface dose differences increased with field size and ranged from 0% to 6%. The field size at which FFF and flattened beams gave the same skin dose increased with decreasing beam energy. Surface dose was higher with MLC fields compared to jaw fields under most conditions, with the difference reaching its maximum at a field size between 4 × 4 cm2 and 6 × 6 cm2 for a given energy and SSD. This study conveyed the magnitude of surface dose in a clinically meaning-ful manner by reporting results normalized to 10 cm depth dose instead of depth of dose

  12. Effects of Essential Oils and Polyunsaturated Fatty Acids on Canine Skin Equivalents: Skin Lipid Assessment and Morphological Evaluation

    PubMed Central

    Cerrato, S.; Ramió-Lluch, L.; Fondevila, D.; Rodes, D.; Brazis, P.; Puigdemont, A.

    2013-01-01

    A canine skin equivalent model has been validated for the assessment of a topical formulation effects. Skin equivalents were developed from freshly isolated cutaneous canine fibroblasts and keratinocytes, after enzymatic digestion of skin samples (n = 8) from different breeds. Fibroblasts were embedded into a collagen type I matrix, and keratinocytes were seeded onto its surface at air-liquid interface. Skin equivalents were supplemented with essential oils and polyunsaturated fatty acid formulation or with vehicle. Skin equivalents were histopathologically and ultrastructurally studied, and the three main lipid groups (free fatty acids, cholesterol, and ceramides) were analyzed. Results showed that the culture method developed resulted in significant improvements in cell retrieval and confluence. Treated samples presented a thicker epidermis with increased number of viable cell layers, a denser and compact stratum corneum, and a more continuous basal membrane. Regarding lipid profile, treated skin equivalents showed a significant increase in ceramide content (51.7 ± 1.3) when compared to untreated (41.6  ±  1.4) samples. Ultrastructural study evidenced a compact and well-organized stratum corneum in both treated and control skin equivalents. In conclusion, cell viability and ceramides increase, after lipid supplementation, are especially relevant for the treatment of skin barrier disruptions occurring in canine atopic dermatitis. PMID:26464904

  13. Gingiva Equivalents Secrete Negligible Amounts of Key Chemokines Involved in Langerhans Cell Migration Compared to Skin Equivalents.

    PubMed

    Kosten, Ilona J; Buskermolen, Jeroen K; Spiekstra, Sander W; de Gruijl, Tanja D; Gibbs, Susan

    2015-01-01

    Both oral mucosa and skin have the capacity to maintain immune homeostasis or regulate immune responses upon environmental assault. Whereas much is known about key innate immune events in skin, little is known about oral mucosa. Comparative studies are limited due to the scarce supply of oral mucosa for ex vivo studies. Therefore, we used organotypic tissue equivalents (reconstructed epithelium on fibroblast-populated collagen hydrogel) to study cross talk between cells. Oral mucosa and skin equivalents were compared regarding secretion of cytokines and chemokines involved in LC migration and general inflammation. Basal secretion, representative of homeostasis, and also secretion after stimulation with TNFα, an allergen (cinnamaldehyde), or an irritant (SDS) were assessed. We found that proinflammatory IL-18 and chemokines CCL2, CCL20, and CXCL12, all involved in LC migration, were predominantly secreted by skin as compared to gingiva. Furthermore, CCL27 was predominantly secreted by skin whereas CCL28 was predominantly secreted by gingiva. In contrast, general inflammatory cytokines IL-6 and CXCL8 were secreted similarly by skin and gingiva. These results indicate that the cytokines and chemokines triggering innate immunity and LC migration are different in skin and gingiva. This differential regulation should be figured into novel therapy or vaccination strategies in the context of skin versus mucosa.

  14. An algorithm for unfolding neutron dose and dose equivalent from digitized recoil-particle tracks

    SciTech Connect

    Bolch, W.E.; Turner, J.E.; Hamm, R.N.

    1986-10-01

    Previous work had demonstrated the feasibility of a digital approach to neutron dosimetry. A Monte Carlo simulation code of one detector design utilizing the operating principles of time-projection chambers was completed. This thesis presents and verifies one version of the dosimeter's computer algorithm. This algorithm processes the output of the ORNL simulation code, but is applicable to all detectors capable of digitizing recoil-particle tracks. Key features include direct measurement of track lengths and identification of particle type for each registered event. The resulting dosimeter should allow more accurate determinations of neutron dose and dose equivalent compared with conventional dosimeters, which cannot measure these quantities directly. Verification of the algorithm was accomplished by running a variety of recoil particles through the simulated detector volume and comparing the resulting absorbed dose and dose equivalent to those unfolded by the algorithm.

  15. A Bioengineered Human Skin Equivalent (HSE) for the Evaluation of Protectants

    DTIC Science & Technology

    2006-11-01

    full thickness skin equivalent that has been optimized by addition of various growth factors, such as ascorbic acid, lipids and a PPAR-α agonist. It...has been characterized for morphology, lipid composition and barrier properties and compared to the commercially available skin equivalents...Compared to these, the HSE possesses closer lipid composition and barrier properties to human skin . The morphology shows a highly differentiated epidermis

  16. 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.

  17. 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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    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 50 th percentile man (175cm height; 70kg mass) is used. Most male members of the U. S. astronaut corps are taller and nearly all have heights that deviate from the 175cm 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 5 th to the 95 th percentiles. Overall the results suggest that calculations of organ dose and dose equivalent may vary by as much as ˜15% as body size is varied from the 5 th to the 95 th percentile in the population used to derive the CAM model data.

  20. 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... Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose equivalent to the embryo/fetus during the entire pregnancy, due to the occupational exposure of a...

  1. 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... Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose equivalent to the embryo/fetus during the entire pregnancy, due to the occupational exposure of a...

  2. 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... Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose equivalent to the embryo/fetus during the entire pregnancy, due to the occupational exposure of a...

  3. 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... Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose equivalent to the embryo/fetus during the entire pregnancy, due to the occupational exposure of a...

  4. 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... Limits § 20.1208 Dose equivalent to an embryo/fetus. (a) The licensee shall ensure that the dose equivalent to the embryo/fetus during the entire pregnancy, due to the occupational exposure of a...

  5. Total effective dose equivalent associated with fixed uranium surface contamination

    SciTech Connect

    Bogard, J.S.; Hamm, R.N.; Ashley, J.C.; Turner, J.E.; England, C.A.; Swenson, D.E.; Brown, K.S.

    1997-04-01

    This report provides the technical basis for establishing a uranium fixed-contamination action level, a fixed uranium surface contamination level exceeding the total radioactivity values of Appendix D of Title 10, Code of Federal Regulations, part 835 (10CFR835), but below which the monitoring, posting, and control requirements for Radiological Areas are not required for the area of the contamination. An area of fixed uranium contamination between 1,000 dpm/100 cm{sup 2} and that level corresponding to an annual total effective dose equivalent (TEDE) of 100 mrem requires only routine monitoring, posting to alert personnel of the contamination, and administrative control. The more extensive requirements for monitoring, posting, and control designated by 10CFR835 for Radiological Areas do not have to be applied for these intermediate fixed-contamination levels.

  6. Effective dose equivalent and effective dose: comparison for common projections in oral and maxillofacial radiology.

    PubMed

    Gibbs, S J

    2000-10-01

    Effective dose equivalents (H(E)) and effective doses (E) for radiographic projections common in dentistry, calculated from the same organ dose distributions, are presented to determine whether the 2 quantities can be directly compared. Doses to all organs and tissues in the head, neck, trunk, and proximal extremities were determined for each projection (intraoral full-mouth radiographic survey, panoramic, cephalometric, temporomandibular tomograms, and submentovertex view) by computer simulation with Monte Carlo methods. H(E) and E were calculated from these complete distributions and by methods prescribed by the International Commission on Radiological Protection (ICRP). H(E) and E computed from complete dose distributions were found comparable within a few percentage points. However, those computed by strict application of ICRP methods were not. For radiographic projections with highly localized dose distributions, such as those common in dentistry, direct comparison of H(E) and E may not be meaningful, unless both computation algorithms are known.

  7. Equivalent normalized total dose estimates in cyberknife radiotherapy dose delivery in prostate cancer hypofractionation regimens.

    PubMed

    Sudahar, H; Kurup, P G G; Murali, V; Mahadev, P; Velmurugan, J

    2012-04-01

    As the α/β value of prostate is very small and lower than the surrounding critical organs, hypofractionated radiotherapy became a vital mode of treatment of prostate cancer. Cyberknife (Accuray Inc., Sunnyvale, CA, USA) treatment for localized prostate cancer is performed in hypofractionated dose regimen alone. Effective dose escalation in the hypofractionated regimen can be estimated if the corresponding conventional 2 Gy per fraction equivalent normalized total dose (NTD) distribution is known. The present study aims to analyze the hypofractionated dose distribution of localized prostate cancer in terms of equivalent NTD. Randomly selected 12 localized prostate cases treated in cyberknife with a dose regimen of 36.25 Gy in 5 fractions were considered. The 2 Gy per fraction equivalent NTDs were calculated using the formula derived from the linear quadratic (LQ) model. Dose distributions were analyzed with the corresponding NTDs. The conformity index for the prescribed target dose of 36.25 Gy equivalent to the NTD dose of 90.63 Gy (α/β = 1.5) or 74.31 Gy (α/β = 3) was ranging between 1.15 and 1.73 with a mean value of 1.32 ± 0.15. The D5% of the target was 111.41 ± 8.66 Gy for α/β = 1.5 and 90.15 ± 6.57 Gy for α/β = 3. Similarly, the D95% was 91.98 ± 3.77 Gy for α/β = 1.5 and 75.35 ± 2.88 Gy for α/β = 3. The mean values of bladder and rectal volume receiving the prescribed dose of 36.25 Gy were 0.83 cm3 and 0.086 cm3, respectively. NTD dose analysis shows an escalated dose distribution within the target for low α/β (1.5 Gy) with reasonable sparing of organs at risk. However, the higher α/β of prostate (3 Gy) is not encouraging the fact of dose escalation in cyberknife hypofractionated dose regimen of localized prostate cancer.

  8. Influence of organs in the ICRP's remainder on effective dose equivalent computed for diagnostic radiation exposures

    SciTech Connect

    Gibbs, S.J.

    1989-04-01

    The ICRP effective dose equivalent has been compared with a weighted dose equivalent, computed by treating the entire remainder instead of the sample of five remainder organs in the ICRP method as uniformly radiosensitive, for dose distributions from three common diagnostic exposures: chest, dental full-mouth and dental panoramic. Complete dose distributions were computed by a Monte Carlo model. In all three cases the effective dose equivalent was greater than the weighted dose equivalent. The difference was only 20% for the chest exam but was more than fivefold for both dental exposures. Dose distributions for the dental exposures were less homogeneous than for the chest examination. Selection of organs to be included in the remainder markedly affects the effective dose equivalent. In the case of highly inhomogeneous dose distributions, the effective dose equivalent probably significantly over-estimates radiation detriment.

  9. Development and application of three-dimensional skin equivalents for the investigation of percutaneous worm invasion.

    PubMed

    Jannasch, M; Groeber, F; Brattig, N W; Unger, C; Walles, H; Hansmann, J

    2015-03-01

    Investigation of percutaneous helminth infection is generally based on animal models or excised skin. As desirable replacement of animal experiments, tissue-engineered skin equivalents have recently been applied in microbial and viral in vitro infection models. In the present study, the applicability of tissue-engineered skin equivalents for the investigation of percutaneous helminth invasion was evaluated. Epidermal and a full-thickness skin equivalents that suit the requirements for helminth invasion studies were developed. Quantitative invasion assays were performed with the skin-invading larvae of the helminths Strongyloides ratti and Schistosoma mansoni. Both skin equivalents provided a physical barrier to larval invasion of the nematode S. ratti, while these larvae could invade and permeate a cell-free collagen scaffold and ex vivo epidermis. In contrast, the epidermal and full-thickness skin equivalents exhibited a human host-specific susceptibility to larvae of trematode S. mansoni, which could well penetrate. Invasion of S. mansoni in cell-free collagen scaffold was lowest for all experimental conditions. Thus, reconstructed epidermis and full-thickness skin equivalents confirmed a high degree of accordance to native tissue. Additionally, not only tailless schistosomula but also cercariae could permeate the skin equivalents, and thus, delayed tail loss hypothesis was supported. The present study indicates that the limitations in predictive infection test systems for human-pathogenic invading helminths can be overcome by tissue-engineered in vitro skin equivalents allowing a substitution of the human skin for analysis of the interaction between parasites and their hosts' tissues. This novel tissue-engineered technology accomplishes the endeavor to save animal lives. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Radiation equivalent dose simulations for long-term interplanetary flights

    NASA Astrophysics Data System (ADS)

    Dobynde, M. I.; Drozdov, A.; Shprits, Y. Y.

    2016-12-01

    Cosmic particle radiation is a limiting factor for the human interplanetary flights. The unmanned flights inside heliosphere and human flights inside of magnetosphere tend to become a routine procedure, whereas there have been only few shot term human flights out of it (Apollo missions 1969-1972) with maximum duration less than a month. Long-term human flights set much higher requirements to the radiation shielding, primarily because of long exposition to cosmic radiation. Inside the helosphere there are two main sources of cosmic radiation: galactic cosmic rays (GCR) and soalr particle events (SPE). GCR come from the outside of heliosphere forming a background of overall radiation that affects the spacecraft. The intensity of GCR is varied according to solar activity, increasing with solar activity decrease and backward, with the modulation time (time between nearest maxima) of 11 yeas. SPE are shot term events, comparing to GCR modulation time, but particle fluxes are much more higher. The probability of SPE increases with the increase of solar activity. Time dependences of the intensity of these two components encourage looking for a time window of flight, when intensity and effect of GCR and SPE would be minimized. Combining GEANT4 Monte Carlo simulations with time dependent model of GCR spectra and data on SPE spectra we show the time dependence of the radiation dose in an anthropomorphic human phantom inside the shielding capsule. Different types of particles affect differently on the human providing more or less harm to the tissues. We use quality factors to recalculate absorbed dose into biological equivalent dose, which give more information about risks for astronaut's health. Incident particles provide a large amount of secondary particles while propagating through the shielding capsule. We try to find an optimal combination of shielding material and thickness, that will effectively decrease the incident particle energy, at the same time minimizing flow

  11. In vivo skin dose measurement in breast conformal radiotherapy

    PubMed Central

    Soleymanifard, Shokouhozaman; Noghreiyan, Atefeh Vejdani; Ghorbani, Mahdi; Jamali, Farideh; Davenport, David

    2016-01-01

    Aim of the study Accurate skin dose assessment is necessary during breast radiotherapy to assure that the skin dose is below the tolerance level and is sufficient to prevent tumour recurrence. The aim of the current study is to measure the skin dose and to evaluate the geometrical/anatomical parameters that affect it. Material and methods Forty patients were simulated by TIGRT treatment planning system and treated with two tangential fields of 6 MV photon beam. Wedge filters were used to homogenise dose distribution for 11 patients. Skin dose was measured by thermoluminescent dosimeters (TLD-100) and the effects of beam incident angle, thickness of irradiated region, and beam entry separation on the skin dose were analysed. Results Average skin dose in treatment course of 50 Gy to the clinical target volume (CTV) was 36.65 Gy. The corresponding dose values for patients who were treated with and without wedge filter were 35.65 and 37.20 Gy, respectively. It was determined that the beam angle affected the average skin dose while the thickness of the irradiated region and the beam entry separation did not affect dose. Since the skin dose measured in this study was lower than the amount required to prevent tumour recurrence, application of bolus material in part of the treatment course is suggested for post-mastectomy advanced breast radiotherapy. It is more important when wedge filters are applied to homogenize dose distribution. PMID:27358592

  12. 10 CFR 835.203 - Combining internal and external equivalent doses.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... External Exposure § 835.203 Combining internal and external equivalent doses. (a) The total effective dose during a year shall be determined by summing the effective dose from external exposures and the committed... 10 Energy 4 2010-01-01 2010-01-01 false Combining internal and external equivalent doses....

  13. Resolution of parameters in the equivalent electrical circuit of the sodium transport mechanism across toad skin.

    PubMed

    Isaacson, L C

    1977-01-28

    In amphibian epithelia, amiloride reduces net sodium transport by hindering the entry of sodium to the active transport mechanism, that is, by increasing the series resistance (Rser). Theoretically, therefore, analysis of amiloride-induced changes in potential differences and short-circuit current should yield numerical estimates of all the parameters in the equivalent electrical circuit of the sodium transport mechanism. The concept has been explored by analysis of such changes in toad skins (Xenopus laevis) bathed in hypotonic sulphate Ringer's, after exposure to varying doses of amiloride, or to amphotericin, dinitrophenol or Pitressin. The estimated values of Rser, of the electromotive force of the sodium pump (ENa), and of the shunt resistance (Rsh) were independent of the dose of amiloride employed. Skins bathed in hypotonic sulphate Ringer's exhibited a progressive rise in ENa. Amphotericin produced a fall in Rser, while dinitrophenol caused a fall in ENa; washout of the drugs reversed these effects. Pitressin produced a fall in both Rser and Rsh, with a rise in ENa. These results are in accord with earlier suggestions regarding the site(s) of action of these agents.

  14. Comparison of organ dose and dose equivalent for human phantoms of CAM vs. MAX

    NASA Astrophysics Data System (ADS)

    Kim, Myung-Hee Y.; Qualls, Garry D.; Slaba, Tony C.; Cucinotta, Francis A.

    2010-04-01

    For the evaluation of organ dose and dose equivalent of astronauts on space shuttle and the International Space Station (ISS) missions, the CAMERA models of CAM (Computerized Anatomical Male) and CAF (Computerized Anatomical Female) of human tissue shielding have been implemented and used in radiation transport model calculations at NASA. One of new human geometry models to meet the “reference person” of International Commission on Radiological Protection (ICRP) is based on detailed Voxel (volumetric and pixel) phantom models denoted for male and female as MAX (Male Adult voXel) and FAX (Female Adult voXel), respectively. We compared the CAM model predictions of organ doses to those of MAX model, since the MAX model represents the male adult body with much higher fidelity than the CAM model currently used at NASA. Directional body-shielding mass was evaluated for over 1500 target points of MAX for specified organs considered to be sensitive to the induction of stochastic effects. Radiation exposures to solar particle event (SPE), trapped protons, and galactic cosmic ray (GCR) were assessed at the specific sites in the MAX phantom by coupling space radiation transport models with the relevant body-shielding mass. The development of multiple-point body-shielding distributions at each organ made it possible to estimate the mean and variance of organ doses at the specific organ. For the estimate of doses to the blood forming organs (BFOs), data on active marrow distributions in adult were used to weight the bone marrow sites over the human body. The discrete number of target points of MAX organs resulted in a reduced organ dose and dose equivalent compared to the results of CAM organs especially for SPE, and should be further investigated. Differences of effective doses between the two approaches were found to be small (<5%) for GCR.

  15. Dose rate, dose-equivalent rate, and quality factor in SLS-1

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Braby, L. A.; Cucinotta, F. A.; Atwell, W.

    1992-01-01

    A tissue-equivalent proportional counter (TEPC) sensitive to the lineal energy range of 0.26-300 keV micrometer-1 was flown on STS-40 (39 degrees x 278 km x 296 km) inside the Spacelab. This instrument was previously flown on STS-31 but was modified to provide a finer resolution at lower lineal energies to better map the South Atlantic Anomaly (SAA) protons. The instrument was turned on 6 June 1991, and operated for 7470 min (124.5 h). The flight duration was characterized by a very large number of X-ray solar flares and enhanced magnetic field fluctuations; however, no significant dose from the solar particles was measured at the location of this instrument. The flight data can be separated into trapped and galactic cosmic radiation parts. The dose rate, dose-equivalent rate and quality factor for trapped radiation were 4.21 +/- 0.03 mrad day-1, 7.72 +/- 0.05 mrem day-1, and 1.83 +/- 0.1, respectively. The dose rate, dose-equivalent rate, and quality factor for galactic cosmic radiation were 5.34 +/- 0.03 mrad day-1, 14.63 +/- 0.06 mrem day-1, and 2.74 +/- 0.1, respectively. The overall quality factor for the flight was 2.38. The dose from the GCR is higher than from SAA protons because of the high inclination and low altitude of this flight. The AP8MAX model of the trapped radiation gives a dose rate of 2.43 mrad day-1 and a quality factor of 1.77. The CREME solar maximum model of galactic cosmic radiation gives a dose rate of 2.54 mrad day-1 and a quality factor of 2.91. Thus the AP8MAX model underestimates the dose by a factor of 1.8 whereas the CREME model leads to an underestimation of the dose by a factor of 2. A comparison of the LET spectra using the AP8MAX model and galactic cosmic radiation transport codes shows only a qualitative agreement.

  16. Assessment of out-of-field absorbed dose and equivalent dose in proton fields

    SciTech Connect

    Clasie, Ben; Wroe, Andrew; Kooy, Hanne; Depauw, Nicolas; Flanz, Jay; Paganetti, Harald; Rosenfeld, Anatoly

    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 inside 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

  17. Development of a dielectric equivalent gel for better impedance matching for human skin.

    PubMed

    Sunaga, Takahiro; Ikehira, Hiroo; Furukawa, Shigeo; Tamura, Mitsuru; Yoshitome, Eiji; Obata, Takayuki; Shinkai, Hiroshi; Tanada, Shuji; Murata, Hajime; Sasaki, Yasuhito

    2003-04-01

    It would be useful to develop a tissue equivalent gel to improve the uniformity of the electromagnetic field in the human body, and for making a tissue equivalent dielectric human phantom. In this study, solid type, water based gelatin-honey gels were developed which have the electrical characteristics of skin tissue. It was demonstrated that a stable and homogeneous gel, with a relative dielectric constant epsilon ' chosen from desired ranges found in skin, can be made for 200-400 MHz.

  18. A first vascularized skin equivalent for as an alternative to animal experimentation.

    PubMed

    Groeber, Florian; Engelhardt, Lisa; Lange, Julia; Kurdyn, Szymon; Schmid, Freia F; Rücker, Christoph; Mielke, Stephan; Walles, Heike; Hansmann, Jan

    2016-01-01

    Tissue-engineered skin equivalents mimic key aspects of the human skin, and can thus be employed as wound coverage for large skin defects or as in vitro test systems as an alternative to animal models. However, current skin equivalents lack a functional vasculature limiting clinical and research applications. This study demonstrates the generation of a vascularized skin equivalent with a perfused vascular network by combining a biological vascularized scaffold (BioVaSc) based on a decellularized segment of a porcine jejunum and a tailored bioreactor system. Briefly, the BioVaSc was seeded with human fibroblasts, keratinocytes, and human microvascular endothelial cells. After 14 days at the air-liquid interface, hematoxylin & eosin and immunohistological staining revealed a specific histological architecture representative of the human dermis and epidermis including a papillary-like architecture at the dermal-epidermal-junction. The formation of the skin barrier was measured non-destructively using impedance spectroscopy. Additionally, endothelial cells lined the walls of the formed vessels that could be perfused with a physiological volume flow. Due to the presence of a complex in-vivo-like vasculature, the here shown skin equivalent has the potential for skin grafting and represents a sophisticated in vitro model for dermatological research.

  19. Characteristics of dosemeter types for skin dose measurements in practice.

    PubMed

    Van Dam, J; Bosmans, H; Marchal, G; Wambersie, A

    2005-01-01

    A growing number of papers report deterministic effects in the skin of patients who have undergone interventional radiological procedures. Dose measurements, and especially skin dose measurements, are therefore increasingly important. Methods and acceptable dosemeters are, however, not clearly defined. This paper is the result of a literature overview with regard to assessing the entrance skin dose during radiological examinations by putting a dosemeter on the patient's skin. The relevant intrinsic characteristics, as well as some examples of clinical use of the different detector types, are presented. In this respect, thermoluminescence, scintillation, semiconductor and film dosemeters are discussed and compared with respect to their practical use.

  20. Construction of new skin models and calculation of skin dose coefficients for electron exposures

    NASA Astrophysics Data System (ADS)

    Yeom, Yeon Soo; Kim, Chan Hyeong; Nguyen, Thang Tat; Choi, Chansoo; Han, Min Cheol; Jeong, Jong Hwi

    2016-08-01

    The voxel-type reference phantoms of the International Commission on Radiological Protection (ICRP), due to their limited voxel resolutions, cannot represent the 50- μm-thick radiosensitive target layer of the skin necessary for skin dose calculations. Alternatively, in ICRP Publication 116, the dose coefficients (DCs) for the skin were calculated approximately, averaging absorbed dose over the entire skin depth of the ICRP phantoms. This approximation is valid for highly-penetrating radiations such as photons and neutrons, but not for weakly penetrating radiations like electrons due to the high gradient in the dose distribution in the skin. To address the limitation, the present study introduces skin polygon-mesh (PM) models, which have been produced by converting the skin models of the ICRP voxel phantoms to a high-quality PM format and adding a 50- μm-thick radiosensitive target layer into the skin models. Then, the constructed skin PM models were implemented in the Geant4 Monte Carlo code to calculate the skin DCs for external exposures of electrons. The calculated values were then compared with the skin DCs of the ICRP Publication 116. The results of the present study show that for high-energy electrons (≥ 1 MeV), the ICRP-116 skin DCs are, indeed, in good agreement with the skin DCs calculated in the present study. For low-energy electrons (< 1 MeV), however, significant discrepancies were observed, and the ICRP-116 skin DCs underestimated the skin dose as much as 15 times for some energies. Besides, regardless of the small tissue weighting factor of the skin ( w T = 0.01), the discrepancies in the skin dose were found to result in significant discrepancies in the effective dose, demonstarting that the effective DCs in ICRP-116 are not reliable for external exposure to electrons.

  1. Biological equivalent dose studies for dose escalation in the stereotactic synchrotron radiation therapy clinical trials

    SciTech Connect

    Prezado, Y.; Fois, G.; Edouard, M.; Nemoz, C.; Renier, M.; Requardt, H.; Esteve, F.; Adam, JF.; Elleaume, H.; Bravin, A.

    2009-03-15

    Synchrotron radiation is an innovative tool for the treatment of brain tumors. In the stereotactic synchrotron radiation therapy (SSRT) technique a radiation dose enhancement specific to the tumor is obtained. The tumor is loaded with a high atomic number (Z) element and it is irradiated in stereotactic conditions from several entrance angles. The aim of this work was to assess dosimetric properties of the SSRT for preparing clinical trials at the European Synchrotron Radiation Facility (ESRF). To estimate the possible risks, the doses received by the tumor and healthy tissues in the future clinical conditions have been calculated by using Monte Carlo simulations (PENELOPE code). The dose enhancement factors have been determined for different iodine concentrations in the tumor, several tumor positions, tumor sizes, and different beam sizes. A scheme for the dose escalation in the various phases of the clinical trials has been proposed. The biological equivalent doses and the normalized total doses received by the skull have been calculated in order to assure that the tolerance values are not reached.

  2. A novel fully-humanised 3D skin equivalent to model early melanoma invasion

    PubMed Central

    Hill, David S; Robinson, Neil D P; Caley, Matthew P; Chen, Mei; O’Toole, Edel A; Armstrong, Jane L; Przyborski, Stefan; Lovat, Penny E

    2015-01-01

    Metastatic melanoma remains incurable, emphasising the acute need for improved research models to investigate the underlying biological mechanisms mediating tumour invasion and metastasis, and to develop more effective targeted therapies to improve clinical outcome. Available animal models of melanoma do not accurately reflect human disease and current in vitro human skin equivalent models incorporating melanoma cells are not fully representative of the human skin microenvironment. We have developed a robust and reproducible, fully-humanised 3D skin equivalent comprising a stratified, terminally differentiated epidermis and a dermal compartment consisting of fibroblast-generated extracellular matrix. Melanoma cells incorporated into the epidermis were able to invade through the basement membrane and into the dermis, mirroring early tumour invasion in vivo. Comparison of our novel 3D melanoma skin equivalent with melanoma in situ and metastatic melanoma indicates this model accurately recreates features of disease pathology, making it a physiologically representative model of early radial and vertical growth phase melanoma invasion. PMID:26330548

  3. In vitro 3D full thickness skin equivalent tissue model using silk and collagen biomaterials

    PubMed Central

    Bellas, Evangelia; Seiberg, Miri; Garlick, Jonathan; Kaplan, David L.

    2013-01-01

    Current approaches to develop skin equivalents often only include the epidermal and dermal components. Yet, full thickness skin includes the hypodermis, a layer below the dermis of adipose tissue containing vasculature, nerves and fibroblasts, necessary to support the epidermis and dermis. In the present study, we developed a full thickness skin equivalent including an epidermis, dermis and hypodermis that could serve as an in vitro model for studying skin development, disease or as a platform for consumer product testing as a means to avoid animal testing. The full thickness skin equivalent was easy to handle and was maintained in culture for greater than 14 days while expressing physiologically relevant morphologies of both the epidermis and dermis, as seen by keratin 10, collagen I and collagen IV expression. The skin equivalent produced glycerol and leptin, markers of adipose tissue metabolism. This work serves as a foundation for our understanding of some of the necessary factors needed to develop a stable, functional model of full-thickness skin. PMID:23161763

  4. Investigating the protective properties of milk phospholipids against ultraviolet light exposure in a skin equivalent model

    NASA Astrophysics Data System (ADS)

    Russell, Ashley; Laubscher, Andrea; Jimenez-Flores, Rafael; Laiho, Lily H.

    2010-02-01

    Current research on bioactive molecules in milk has documented health advantages of bovine milk and its components. Milk Phospholipids, selected for this study, represent molecules with great potential benefit in human health and nutrition. In this study we used confocal reflectance and multiphoton microscopy to monitor changes in skin morphology upon skin exposure to ultraviolet light and evaluate the potential of milk phospholipids in preventing photodamage to skin equivalent models. The results suggest that milk phospholipids act upon skin cells in a protective manner against the effect of ultraviolet (UV) radiation. Similar results were obtained from MTT tissue viability assay and histology.

  5. 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.

  6. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation

    SciTech Connect

    Sondhaus, C.A.; Bond, V.P.; Feinendegen, L.E. )

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  7. Cell-oriented alternatives to dose, quality factor, and dose equivalent for low-level radiation.

    PubMed

    Sondhaus, C A; Bond, V P; Feinendegen, L E

    1990-07-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to sensitive target volumes within a small fraction of the tissue cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Applying this cell response or hit size effectiveness function (HSEF) to different radiations and normalizing to equal numbers of responses produced by each radiation should define its radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose equivalent, both of which are confounded when applied to low-level irradiations. Similar cell response probability functions calculated from different experimental data are presented.

  8. Impaired Tight Junctions in Atopic Dermatitis Skin and in a Skin-Equivalent Model Treated with Interleukin-17.

    PubMed

    Yuki, Takuo; Tobiishi, Megumi; Kusaka-Kikushima, Ayumi; Ota, Yukiko; Tokura, Yoshiki

    2016-01-01

    Tight junction (TJ) dysfunction in the stratum granulosum leads to aberrant barrier function of the stratum corneum (SC) in the epidermis. However, it is unclear whether TJs are perturbed in atopic dermatitis (AD), a representative aberrant SC-related skin disease, and whether some factors related to AD pathogenesis induce TJ dysfunction. To address these issues, we investigated the alterations of TJs in AD skin and the effects of Th2 and Th17 cytokines on TJs in a skin-equivalent model. The levels of TJ proteins were determined in the epidermis of nonlesional and lesional skin sites of AD. Western blot and immunohistochemical analyses revealed that the levels of zonula occludens 1 were decreased in the nonlesional sites of AD, and the levels of zonula occludens 1 and claudin-1 were decreased in the lesional sites relative to the levels in skin from healthy subjects. Next, we examined the effects of interleukin (IL)-4, tumor necrosis factor-α, IL-17, and IL-22 on the TJ barrier in a skin-equivalent model. Only IL-17 impaired the TJ barrier. Furthermore, we observed a defect in filaggrin monomer degradation in the IL-17-treated skin model. Thus, TJs are dysfunctional in AD, at least partly, due to the effect of IL-17, which may result in an aberrant SC barrier.

  9. Impaired Tight Junctions in Atopic Dermatitis Skin and in a Skin-Equivalent Model Treated with Interleukin-17

    PubMed Central

    Yuki, Takuo; Tobiishi, Megumi; Kusaka-Kikushima, Ayumi; Ota, Yukiko; Tokura, Yoshiki

    2016-01-01

    Tight junction (TJ) dysfunction in the stratum granulosum leads to aberrant barrier function of the stratum corneum (SC) in the epidermis. However, it is unclear whether TJs are perturbed in atopic dermatitis (AD), a representative aberrant SC-related skin disease, and whether some factors related to AD pathogenesis induce TJ dysfunction. To address these issues, we investigated the alterations of TJs in AD skin and the effects of Th2 and Th17 cytokines on TJs in a skin-equivalent model. The levels of TJ proteins were determined in the epidermis of nonlesional and lesional skin sites of AD. Western blot and immunohistochemical analyses revealed that the levels of zonula occludens 1 were decreased in the nonlesional sites of AD, and the levels of zonula occludens 1 and claudin-1 were decreased in the lesional sites relative to the levels in skin from healthy subjects. Next, we examined the effects of interleukin (IL)-4, tumor necrosis factor-α, IL-17, and IL-22 on the TJ barrier in a skin-equivalent model. Only IL-17 impaired the TJ barrier. Furthermore, we observed a defect in filaggrin monomer degradation in the IL-17–treated skin model. Thus, TJs are dysfunctional in AD, at least partly, due to the effect of IL-17, which may result in an aberrant SC barrier. PMID:27588419

  10. Construction of three-dimensional dermo-epidermal skin equivalents using cell coating technology and their utilization as alternative skin for permeation studies and skin irritation tests.

    PubMed

    Akagi, Takami; Nagura, Mayuka; Hiura, Ayami; Kojima, Hajime; Akashi, Mitsuru

    2017-03-23

    In vitro generated human skin equivalents are generating interest as promising tools in basic research, as alternatives to animal testing and for clinical applications in regenerative medicine. For prediction of skin irritation and corrosion, three-dimensional (3D) human skin equivalents consisting of differentiated human keratinocytes have been developed and some models have been internationally accepted. However, more delicate assessments using full-thickness skin models, such as skin sensitization tests cannot be performed because of the lack of a dermis containing fibroblasts or appendages. In a previous study, we developed dermo-epidermal human skin equivalents (DESEs) using a cell coating technique, which employs cell surface coating by layer-by-layer (LbL) assembled extracellular matrix (ECM) films. The DESEs with dermis consisting of normal human dermal fibroblasts (NHDF) and epidermis consisting of human keratinocytes (KC) were easily fabricated by using this technology. In this study, the constructed DESEs were evaluated as an alternative skin for skin permeation and irritation tests. A good relationship of permeability coefficient of chemicals was observed between the DESEs and human skin data. We investigated whether the DESEs, a new in vitro skin model, are able to identify skin irritant and non-irritant substances among 20 reference chemicals. It was confirmed that the DESEs are applicable to skin irritation testing as defined in the European Centre for the Validation of Alternative Methods (ECVAM) Performance Standard (OECD Test Guideline 439). We further studied the construction of the DESEs with density-controlled blood capillary networks using human umbilical vein endothelial cells (HUVEC). The results suggest that DESEs allowing incorporation of skin appendages are more promising alternatives to animal testing, and can be applied to the design of physiologically relevant in vitro skin models.

  11. The effect of field modifier blocks on the fast photoneutron dose equivalent from two high-energy medical linear accelerators.

    PubMed

    Hashemi, Seyed Mehdi; Hashemi-Malayeri, Bijan; Raisali, Gholamreza; Shokrani, Parvaneh; Sharafi, Ali Akbar; Jafarizadeh, Mansour

    2008-01-01

    High-energy linear accelerators (linacs) have several advantages, including low skin doses and high dose rates at deep-seated tumours. But, at energies more than 8 MeV, photonuclear reactions produce neutron contamination around the therapeutic beam, which may induce secondary malignancies. In spite of improvements achieved in medical linac designs, many countries still use conventional (non-intensity-modulated radiotherapy) linacs. Hence, in these conventional machines, fitting the beam over the treatment volume may require using blocks. Therefore, the effect of these devices on neutron production of linacs needs to be studied. The aim of this study was to investigate the effect of field shaping blocks on photoneutron dose in the treatment plane for two high-energy medical linacs. Two medical linacs, a Saturn 43 (25 MeV) and an Elekta SL 75/25 (18 MeV), were studied. Polycarbonate (PC) films were used to measure the fluence of photoneutrons produced by these linacs. After electrochemical etching of the PC films, the neutron dose equivalent was calculated at the isocentre and 50 cm away from the isocentre. It was noted that by increasing the distance from the centre of the X-ray beam towards the periphery, the photoneutron dose equivalent decreases rapidly for both the open and blocked fields. Increasing the energy of the photons causes an increase in the amount of photoneutron dose equivalent. At 25 MeV photon energy, the lead blocks cause a meaningful increase in the dose equivalent of photoneutrons. In this research, a 30% increase was seen in neutron dose contribution to central axis dose at the isocentre of a 25 MeV irregular field shaped by lead blocks. It is concluded that lead blocks must be considered as a source of photoneutron production when treating irregular fields with high-energy photons.

  12. Melanin Transfer in Human 3D Skin Equivalents Generated Exclusively from Induced Pluripotent Stem Cells

    PubMed Central

    Gledhill, Karl; Guo, Zongyou; Umegaki-Arao, Noriko; Higgins, Claire A.; Itoh, Munenari; Christiano, Angela M.

    2015-01-01

    The current utility of 3D skin equivalents is limited by the fact that existing models fail to recapitulate the cellular complexity of human skin. They often contain few cell types and no appendages, in part because many cells found in the skin are difficult to isolate from intact tissue and cannot be expanded in culture. Induced pluripotent stem cells (iPSCs) present an avenue by which we can overcome this issue due to their ability to be differentiated into multiple cell types in the body and their unlimited growth potential. We previously reported generation of the first human 3D skin equivalents from iPSC-derived fibroblasts and iPSC-derived keratinocytes, demonstrating that iPSCs can provide a foundation for modeling a complex human organ such as skin. Here, we have increased the complexity of this model by including additional iPSC-derived melanocytes. Epidermal melanocytes, which are largely responsible for skin pigmentation, represent the second most numerous cell type found in normal human epidermis and as such represent a logical next addition. We report efficient melanin production from iPSC-derived melanocytes and transfer within an entirely iPSC-derived epidermal-melanin unit and generation of the first functional human 3D skin equivalents made from iPSC-derived fibroblasts, keratinocytes and melanocytes. PMID:26308443

  13. Melanin Transfer in Human 3D Skin Equivalents Generated Exclusively from Induced Pluripotent Stem Cells.

    PubMed

    Gledhill, Karl; Guo, Zongyou; Umegaki-Arao, Noriko; Higgins, Claire A; Itoh, Munenari; Christiano, Angela M

    2015-01-01

    The current utility of 3D skin equivalents is limited by the fact that existing models fail to recapitulate the cellular complexity of human skin. They often contain few cell types and no appendages, in part because many cells found in the skin are difficult to isolate from intact tissue and cannot be expanded in culture. Induced pluripotent stem cells (iPSCs) present an avenue by which we can overcome this issue due to their ability to be differentiated into multiple cell types in the body and their unlimited growth potential. We previously reported generation of the first human 3D skin equivalents from iPSC-derived fibroblasts and iPSC-derived keratinocytes, demonstrating that iPSCs can provide a foundation for modeling a complex human organ such as skin. Here, we have increased the complexity of this model by including additional iPSC-derived melanocytes. Epidermal melanocytes, which are largely responsible for skin pigmentation, represent the second most numerous cell type found in normal human epidermis and as such represent a logical next addition. We report efficient melanin production from iPSC-derived melanocytes and transfer within an entirely iPSC-derived epidermal-melanin unit and generation of the first functional human 3D skin equivalents made from iPSC-derived fibroblasts, keratinocytes and melanocytes.

  14. Exploring the potentials of nurture: 2(nd) and 3(rd) generation explant human skin equivalents.

    PubMed

    Danso, Mogbekeloluwa O; van Drongelen, Vincent; Mulder, Aat; Gooris, Gert; van Smeden, Jeroen; El Ghalbzouri, Abdoelwaheb; Bouwstra, Joke A

    2015-02-01

    Explant human skin equivalents (Ex-HSEs) can be generated by placing a 4mm skin biopsy onto a dermal equivalent. The keratinocytes migrate from the biopsy onto the dermal equivalent, differentiate and form the epidermis of 1(st) generation Ex-HSEs. This is especially suitable for the expansion of skin material from which only small fragments of skin can be harvested e.g. diseased skin. We evaluated whether 2(nd) and 3(rd) generation Ex-HSEs can also be generated from a single skin biopsy whilst maintaining the epidermal properties of 1(st) generation Ex-HSEs and native human skin. 2(nd) generation Ex-HSEs were produced by placing a biopsy from the 1(st) generation Ex-HSE onto a new dermal equivalent. Likewise, the 3(rd) generation Ex-HSEs were generated from a 2(nd) generation Ex-HSE biopsy. We show for the first time that Ex-HSEs can be passaged to the 2(nd) and 3(rd) generation and display similar epidermal morphology and expression of differentiation markers as in native human skin and 1(st) generation Ex-HSEs except for involucrin. The 2(nd) and 3(rd) generation Ex-HSEs also show many similarities with 1(st) generation Ex-HSEs in lipid properties e.g. presence of all lipid classes, similar fatty acid chain length distribution and lamellar lipid organization. However, some differences arise in increased level of hexagonal lateral packing and a change in ceramide profiling. The changes in specific lipid classes were also accompanied by changes in the expression of the enzymes responsible for their synthesis. The expansion of skin biopsies to the 2(nd) and 3(rd) generation Ex-HSEs could be a promising method to expand valuable epidermal tissue to analyze morphological and differentiation parameters in the native epidermis. Copyright © 2015 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  15. Risk equivalent of exposure versus dose of radiation

    SciTech Connect

    Bond, V.P.

    1986-01-01

    This report describes a risk analysis study of low-dose irradiation and the resulting biological effects on a cell. The author describes fundamental differences between the effects of high-level exposure (HLE) and low-level exposure (LLE). He stresses that the concept of absorbed dose to an organ is not a dose but a level of effect produced by a particular number of particles. He discusses the confusion between a linear-proportional representation of dose limits and a threshold-curvilinear representation, suggesting that a LLE is a composite of both systems. (TEM)

  16. Photoprotection by pistachio bioactives in a 3-dimensional human skin equivalent tissue model.

    PubMed

    Chen, C-Y Oliver; Smith, Avi; Liu, Yuntao; Du, Peng; Blumberg, Jeffrey B; Garlick, Jonathan

    2017-01-25

    Reactive oxygen species (ROS) generated during ultraviolet (UV) light exposure can induce skin damage and aging. Antioxidants can provide protection against oxidative injury to skin via "quenching" ROS. Using a validated 3-dimensional (3D) human skin equivalent (HSE) tissue model that closely mimics human skin, we examined whether pistachio antioxidants could protect HSE against UVA-induced damage. Lutein and γ-tocopherol are the predominant lipophilic antioxidants in pistachios; treatment with these compounds prior to UVA exposure protected against morphological changes to the epithelial and connective tissue compartments of HSE. Pistachio antioxidants preserved overall skin thickness and organization, as well as fibroblast morphology, in HSE exposed to UVA irradiation. However, this protection was not substantiated by the analysis of the proliferation of keratinocytes and apoptosis of fibroblasts. Additional studies are warranted to elucidate the basis of these discordant results and extend research into the potential role of pistachio bioactives promoting skin health.

  17. Calculation of the absorbed dose and dose equivalent induced by medium energy neutrons and protons and comparison with experiment

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Bishop, B. L.

    1972-01-01

    Monte Carlo calculations have been carried out to determine the absorbed dose and dose equivalent for 592-MeV protons incident on a cylindrical phantom and for neutrons from 580-MeV proton-Be collisions incident on a semi-infinite phantom. For both configurations, the calculated depth dependence of the absorbed dose is in good agreement with experimental data.

  18. Characterization of a new tissue-engineered human skin equivalent with hair.

    PubMed

    Michel, M; L'Heureux, N; Pouliot, R; Xu, W; Auger, F A; Germain, L

    1999-06-01

    We designed a new tissue-engineered skin equivalent in which complete pilosebaceous units were integrated. This model was produced exclusively from human fibroblasts and keratinocytes and did not contain any synthetic material. Fibroblasts were cultured for 35 d with ascorbic acid and formed a thick fibrous sheet in the culture dish. The dermal equivalent was composed of stacked fibroblast sheets and exhibited some ultrastructural organization found in normal connective tissues. Keratinocytes seeded on this tissue formed a stratified and cornified epidermis and expressed typical markers of differentiation (keratin 10, filaggrin, and transglutaminase). After 4 wk of culture, a continuous and ultrastructurally organized basement membrane was observed and associated with the expression of laminin and collagen IV and VII. Complete pilosebaceous units were obtained by thermolysin digestion and inserted in this skin equivalent in order to assess the role of the transfollicular route in percutaneous absorption. The presence of hair follicles abolished the lag-time observed during hydrocortisone diffusion and increased significantly its rate of penetration in comparison to the control (skin equivalent with sham hair insertion). Therefore, this new hairy human skin equivalent model allowed an experimental design in which the only variable was the presence of pilosebaceous units and provided new data confirming the importance of hair follicles in percutaneous absorption.

  19. An In Vitro Skin Equivalent for Evaluation of Skin Absorption of Compounds

    DTIC Science & Technology

    2008-12-01

    to mimic the barrier properties of human skin in vivo. The HSE has been characterized for morphology, lipid composition and barrier properties and...impaired desquamation (Vicanová, J., Boelsma, E. et al. 1998), abnormal skin lipid profiles or the presence of unkeratinized microscopic foci (Mak...simulate the barrier properties of skin in vivo. The model has been characterized for lipid composition, morphology and permeability to various model

  20. 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

  1. 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.

  2. Depigmentation effect of kadsuralignan F on melan-a murine melanocytes and human skin equivalents.

    PubMed

    Goh, Myeong-Jin; Lee, Hae-Kwang; Cheng, Liang; Kong, De-Yun; Yeon, Jae-Ho; He, Quan-Quan; Cho, Jun-Cheol; Na, Yong Joo

    2013-01-15

    The development of melanogenic inhibitors is important for the prevention of hyperpigmentation, and, recently, consideration has been given to natural materials or traditionally used ingredients such as Chinese medicine. The aim of this study is the evaluation of a new anti-melanogenic candidate, kadsuralignan F, from the natural plant Kadsura coccinea, as well as the determination of mechanisms of melanogenesis inhibition at a molecular level. Kadsuralignan F significantly reduced melanin synthesis in a dose-dependent manner in a murine melanocyte cell line and human skin equivalents. There was no direct inhibition on mushroom tyrosinase or cell-extract tyrosinase activity, and mRNA expression of tyrosinase and other melanogenic genes such as tyrosinase-related protein-1 (trp-1) or trp-2 were not affected by kadsuralignan F. Interestingly, the protein level of tyrosinase was dramatically downregulated with kadsuralignan F treatment. We found that a decrease of tyrosinase protein by kadsuralignan F was fully recovered by MG132, a proteasome inhibitor, but not by chloroquine, a lysosome inhibitor. In this study, we found that kadsuralignan F, a lignan from an extract of Kadsura coccinea, has an inhibitory activity on melanin synthesis through tyrosinase degradation. These findings suggest that kadsuralignan F can be used as an active ingredient for hyperpigmentation treatment.

  3. Depigmentation Effect of Kadsuralignan F on Melan-A Murine Melanocytes and Human Skin Equivalents

    PubMed Central

    Goh, Myeong-Jin; Lee, Hae-Kwang; Cheng, Liang; Kong, De-Yun; Yeon, Jae-Ho; He, Quan-Quan; Cho, Jun-Cheol; Na, Yong Joo

    2013-01-01

    The development of melanogenic inhibitors is important for the prevention of hyperpigmentation, and, recently, consideration has been given to natural materials or traditionally used ingredients such as Chinese medicine. The aim of this study is the evaluation of a new anti-melanogenic candidate, kadsuralignan F, from the natural plant Kadsura coccinea, as well as the determination of mechanisms of melanogenesis inhibition at a molecular level. Kadsuralignan F significantly reduced melanin synthesis in a dose-dependent manner in a murine melanocyte cell line and human skin equivalents. There was no direct inhibition on mushroom tyrosinase or cell-extract tyrosinase activity, and mRNA expression of tyrosinase and other melanogenic genes such as tyrosinase-related protein-1 (trp-1) or trp-2 were not affected by kadsuralignan F. Interestingly, the protein level of tyrosinase was dramatically downregulated with kadsuralignan F treatment. We found that a decrease of tyrosinase protein by kadsuralignan F was fully recovered by MG132, a proteasome inhibitor, but not by chloroquine, a lysosome inhibitor. In this study, we found that kadsuralignan F, a lignan from an extract of Kadsura coccinea, has an inhibitory activity on melanin synthesis through tyrosinase degradation. These findings suggest that kadsuralignan F can be used as an active ingredient for hyperpigmentation treatment. PMID:23322017

  4. 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.

  5. Type IV collagen aggregates promote keratinocyte proliferation and formation of epidermal layer in human skin equivalents.

    PubMed

    Matsuura-Hachiya, Yuko; Arai, Koji Y; Muraguchi, Taichi; Sasaki, Tasuku; Nishiyama, Toshio

    2017-03-07

    Type IV collagen isolated from lens capsule without enzymatic treatment is known to form a gel under physiological condition and influences cellular activities. In case of human keratinocytes, the suppression of proliferation on reconstituted type IV collagen gels was reported in monolayer culture. In this study, we examined effects of type IV collagen isolated from porcine lens capsule on epidermal formation in human skin equivalents. Type IV collagen aggregates were prepared under the culture condition and the aggregates suppressed keratinocyte proliferation in monolayer culture as well as the culture on the gels. In human skin equivalents type IV collagen aggregates were reconstituted on the surface of contracted collagen gels containing human dermal fibroblasts and the keratinocytes were then cultured on the aggregates for 14 days. Interestingly, in human skin equivalents with type IV collagen aggregates, the BrdU-positive keratinocytes were increased and the thickness of the epidermal layer was around twice than that of control culture. Epidermal differentiation markers were expressed in the upper layer of the epidermis and the defined deposition of human basement membrane components were increased at the dermal-epidermal junction. These results indicate that the type IV collagen aggregates stimulate the proliferation of basal keratinocytes and improve the stratification of epidermal layers in human skin equivalents. This article is protected by copyright. All rights reserved.

  6. Marrow cell kinetics model: Equivalent prompt dose approximations for two special cases

    SciTech Connect

    Morris, M.D.; Jones, T.D.

    1992-11-01

    Two simple algebraic expressions are described for approximating the ``equivalent prompt dose`` as defined in the model of Jones et al. (1991). These approximations apply to two specific radiation exposure patterns: (1) a pulsed dose immediately followed by a protracted exposure at relatively low, constant dose rate and (2) an exponentially decreasing exposure field.

  7. Marrow cell kinetics model: Equivalent prompt dose approximations for two special cases

    SciTech Connect

    Morris, M.D.; Jones, T.D.

    1992-11-01

    Two simple algebraic expressions are described for approximating the equivalent prompt dose'' as defined in the model of Jones et al. (1991). These approximations apply to two specific radiation exposure patterns: (1) a pulsed dose immediately followed by a protracted exposure at relatively low, constant dose rate and (2) an exponentially decreasing exposure field.

  8. Production of an acellular matrix from amniotic membrane for the synthesis of a human skin equivalent.

    PubMed

    Sanluis-Verdes, Anahí; Yebra-Pimentel Vilar, Maria Teresa; García-Barreiro, Juan Javier; García-Camba, Marta; Ibáñez, Jacinto Sánchez; Doménech, Nieves; Rendal-Vázquez, Maria Esther

    2015-09-01

    Human amniotic membrane (HAM) has useful properties as a dermal matrix substitute. The objective of our work was to obtain, using different enzymatic or chemical treatments to eliminate cells, a scaffold of acellular HAM for later use as a support for the development of a skin equivalent. The HAM was separated from the chorion, incubated and cryopreserved. The membrane underwent different enzymatic and chemical treatments to eliminate the cells. Fibroblasts and keratinocytes were separately obtained from skin biopsies of patients following a sequential double digestion with first collagenase and then trypsin-EDTA (T/E). A skin equivalent was then constructed by seeding keratinocytes on the epithelial side and fibroblasts on the chorionic side of the decellularizated HAM. Histological, immunohistochemical, inmunofluorescent and molecular biology studies were performed. Treatment with 1% T/E at 37 °C for 30 min totally removed epithelial and mesenchymal cells. The HAM thus treated proved to be a good matrix to support adherence of cells and allowed the achievement of an integral and intact scaffold for development of a skin equivalent, which could be useful as a skin substitute for clinical use.

  9. Skin dose in breast brachytherapy: Defining a robust metric.

    PubMed

    Hilts, Michelle; Halperin, Heather; Morton, Dan; Batchelar, Deidre; Bachand, Francois; Chowdhury, Rezwan; Crook, Juanita

    2015-01-01

    To define a simple, robust, and relevant metric for measuring skin dose in breast brachytherapy. Postoperative treatment plans (Day 0) for 15 permanent breast seed implant (PBSI) and 10 multicatheter high-dose-rate (MC-HDR) brachytherapy patients were included. Retrospectively, three skin structures were contoured: 2 mm external from the body; and subsurface layers 2 mm and 4 mm thick. Maximum point dose (Dmax), doses to small volumes (e.g., D0.2cc), and the volumes receiving a percentage of the prescription dose (V%, e.g., V66) were calculated. D0.2cc was investigated as a surrogate to the dose given to 1 cm(2) of skin (D1cm(2)). Pearson product-moment correlation (R(2)) was computed between metrics. Observed trends were consistent across brachytherapy technique. V% did not correlate well with any other metrics: median (range) R(2), 0.63 (0.43, 0.77) and 0.69 (0.3, 0.89) for PBSI and MC-HDR, respectively. Dmax was inconsistently correlated across contours and not well correlated with doses to small volumes: median (range) R(2), 0.85 (0.76, 0.93) and 0.88 (0.83, 0.93) for PBSI and MC-HDR, respectively. In contrast, doses to small volumes were consistently well correlated, even across skin layers: D0.1cc vs. D0.2cc median (range) R(2), 0.98 (0.97, 0.99) and 0.97 (0.94, 0.99) for PBSI and MC-HDR, respectively. Doses to small volumes are robust measures of breast skin dose and given skin's strong area effect, D0.2cc for a 2 mm thick skin layer, a simple surrogate of D1cm(2), is recommended for recording skin dose in any breast brachytherapy. Dmax is not robust and should be avoided. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  10. New equivalent sphere approximation for BFO dose estimation: solar particle events

    NASA Astrophysics Data System (ADS)

    Bier, S. G.; Townsend, L. W.; Maxson, W. L.

    The use of a 5 cm tissue equivalent sphere model to obtain dose estimates for the blood-forming organs from energetic space radiations has been widespread for some time. Recent studies have noted that calculated doses obtained using the 5 cm equivalent sphere model were very conservatively overestimated when compared to those obtained with a detailed body geometry. Such conservatism may introduce significant shield weight penalties if used in spacecraft design studies. The use of detailed human geometry models will yield more accurate estimates of blood-forming organ doses and dose equivalents, but with a concomitant reduction in computational ease. In this work we propose a preliminary, yet new blood-forming organ equivalent sphere approximation for use in estimating SPE exposure and in shield design studies that is more realistic than the existing 5-cm approximation.

  11. Unraveling barrier properties of three different in-house human skin equivalents.

    PubMed

    Thakoersing, Varsha S; Gooris, Gerrit S; Mulder, Aat; Rietveld, Marion; El Ghalbzouri, Abdoelwaheb; Bouwstra, Joke A

    2012-01-01

    Human skin equivalents (HSEs) are three-dimensional culture models that are used as a model for native human skin. In this study the barrier properties of two novel HSEs, the fibroblast-derived matrix model (FDM) and the Leiden epidermal model (LEM), were compared with the full-thickness collagen model (FTM) and human skin. Since the main skin barrier is located in the lipid regions of the upper layer of the skin, the stratum corneum (SC), we investigated the epidermal morphology, expression of differentiation markers, SC permeability, lipid composition, and lipid organization of all HSEs and native human skin. Our results demonstrate that the barrier function of the FDM and LEM improved compared with that of the FTM, but all HSEs are more permeable than human skin. Further, the FDM and LEM have a relatively lower free fatty acid content than the FTM and human skin. Several similarities between the FDM, LEM and FTM were observed: (1) the morphology and the expression of the investigated differentiation markers were similar to those observed in native human skin, except for the observed expression of keratin 16 and premature expression of involucrin that were detected in all HSEs, (2) the lipids in the SC of all HSEs were arranged in lipid lamellae, similar to human skin, but show an increase in the number of lipid lamellae in the intercellular regions and (3) the SC lipids of all HSEs show a less densely packed lateral lipid organization compared with human SC. These findings indicate that the HSEs mimic many aspects of native human skin, but differ in their barrier properties.

  12. The Influence of Radon (Gas and Progeny) and Weather Conditions on Ambient Dose Equivalent Rate.

    PubMed

    Márquez, J L; Benito, G; Saez, J C; Navarro, N; Alvarez, A; Quiñones, J

    2016-08-13

    The purpose of this study is to identify the influence of radon (gas and progeny) on the ambient dose equivalent rate measured at the reference station ESMERALDA, where continuous measurements of the ambient dose equivalent rate (every 10 min) combined with activity concentration measurements of radon gas and radon progeny as well as meteorological parameters have been collected. This study has been performed using a correlation study based on a principal components analysis and the Spearman's rank correlation coefficient.

  13. Measurement of skin dose variations produced by a silicon-based protective dressing in radiotherapy.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N; Metcalfe, Peter

    2002-06-07

    Variations in skin dose caused by a silicon-based burn dressing used in radiotherapy during treatment have been investigated. Measurement of these variations in skin dose has been achieved using thermoluminescent dosimeters (TLDs) and Gafchromic film. For a 6 MV x-ray beam results have shown that an approximately 0.4 mm thick silicon mesh dressing increases the average surface dose by approximately 12.5% to 14% of the maximum and average dose at 1 mm depth and by 4% to 6% of the maximum for field sizes ranging from 5 cm x 5 cm up to 40 cm x 40 cm at 100 cm source to surface distance (SSD). The radiation effective thickness of the silicon dressing was calculated to be 0.5 mm +/- 0.05 mm water equivalent. TLDs of various thicknesses provide point-dose assessment and Gafchromic film can provide a detailed two-dimensional dose map with a high spatial resolution. Results have shown that a large variation in skin dose is delivered under the dressing depending on the amount of material directly above it as defined by the silicon mesh outline.

  14. Peripheral equivalent neutron dose model implementation for radiotherapy patients.

    PubMed

    Irazola, L; Terrón, J A; Sánchez-Nieto, B; Roberto, B; Sánchez-Doblado, F

    2017-03-31

    Neutron peripheral contamination in high-energy radiotherapy implies an increase of secondary radiation-induced cancer risk. Although peripheral neutron dose (PND) has been evaluated in organs, few studies have been performed regarding patient size. This work aims to improve an existing methodology for adult patient PND estimations to generalize it to young and children, for its implementation in treatment planning systems (TPS). As a first step, we aimed to generalize the previous model to be usable with any thermal neutron detector. Then, taking into account total neutron spectra and dose-to-point thermal neutron fluence measurements for three phantom sizes (adult, teen and child) and two common treatment locations (H&N and abdomen), the new model was proposed. It represents an upgraded parameterization and extension of the existing one, including patient anatomy. Finally, comparison between estimations and measurements, as well as validation against the original model, was carried out for 510 measured patients. Concordance found between experimental and theoretical estimations makes us confident about later implementation in treatment planning systems. Comparison among the previous and upgraded models shows no significant differences for the adult case. However, an important underestimation (34.1% on average) can be observed regarding child case for the original one. An improved generalization of an existing PND model, considering patient anatomy has been validated and used in real patients. The final methodology is easily implementable in clinical routine and TPS thanks to the ready availability of input parameters (patient height and weight, high-energy MU and facility characterization). Copyright © 2017. Published by Elsevier Ltd.

  15. Skin Dose Impact from Vacuum Immobilization Device and Carbon Fiber Couch in Intensity Modulated Radiation Therapy for Prostate Cancer

    SciTech Connect

    Lee, K.-W.; Wu, J.-K.; Jeng, S.-C.; Hsueh Liu Yen-Wan; Cheng, Jason Chia-Hsien

    2009-10-01

    To investigate the unexpected skin dose increase from intensity-modulated radiation therapy (IMRT) on vacuum cushions and carbon-fiber couches and then to modify the dosimetric plan accordingly. Eleven prostate cancer patients undergoing IMRT were treated in prone position with a vacuum cushion. Two under-couch beams scattered the radiation from the vacuum cushion and carbon-fiber couch. The IMRT plans with both devices contoured were compared with the plans not contouring them. The skin doses were measured using thermoluminescent dosimeters (TLDs) placed on the inguinal regions in a single IMRT fraction. Tissue equivalent thickness was transformed for both devices with the relative densities. The TLD-measured skin doses (59.5 {+-} 9.5 cGy and 55.6 {+-} 5.9 cGy at left and right inguinal regions, respectively) were significantly higher than the calculated doses (28.7 {+-} 4.7 cGy; p = 2.2 x 10{sup -5} and 26.2 {+-} 4.3 cGy; p = 1.5 x 10{sup -5}) not contouring the vacuum cushion and carbon-fiber couch. The calculated skin doses with both devices contoured (59.1 {+-} 8.8 cGy and 55.5 {+-} 5.7 cGy) were similar to the TLD-measured doses. In addition, the calculated skin doses using the vacuum cushion and a converted thickness of the simulator couch were no different from the TLD-measured doses. The recalculated doses of rectum and bladder did not change significantly. The dose that covered 95% of target volume was less than the prescribed dose in 4 of 11 patients, and this problem was solved after re-optimization applying the corrected contours. The vacuum cushion and carbon-fiber couch contributed to increased skin doses. The tissue-equivalent-thickness method served as an effective way to correct the dose variations.

  16. Skin dose impact from vacuum immobilization device and carbon fiber couch in intensity modulated radiation therapy for prostate cancer.

    PubMed

    Lee, Kuo-Wei; Wu, Jian-Kuen; Jeng, Shiu-Chen; Hsueh Liu, Yen-Wan; Cheng, Jason Chia-Hsien

    2009-01-01

    To investigate the unexpected skin dose increase from intensity-modulated radiation therapy (IMRT) on vacuum cushions and carbon-fiber couches and then to modify the dosimetric plan accordingly. Eleven prostate cancer patients undergoing IMRT were treated in prone position with a vacuum cushion. Two under-couch beams scattered the radiation from the vacuum cushion and carbon-fiber couch. The IMRT plans with both devices contoured were compared with the plans not contouring them. The skin doses were measured using thermoluminescent dosimeters (TLDs) placed on the inguinal regions in a single IMRT fraction. Tissue equivalent thickness was transformed for both devices with the relative densities. The TLD-measured skin doses (59.5 +/- 9.5 cGy and 55.6 +/- 5.9 cGy at left and right inguinal regions, respectively) were significantly higher than the calculated doses (28.7 +/- 4.7 cGy; p = 2.2 x 10(-5) and 26.2 +/- 4.3 cGy; p = 1.5 x 10(-5)) not contouring the vacuum cushion and carbon-fiber couch. The calculated skin doses with both devices contoured (59.1 +/- 8.8 cGy and 55.5 +/- 5.7 cGy) were similar to the TLD-measured doses. In addition, the calculated skin doses using the vacuum cushion and a converted thickness of the simulator couch were no different from the TLD-measured doses. The recalculated doses of rectum and bladder did not change significantly. The dose that covered 95% of target volume was less than the prescribed dose in 4 of 11 patients, and this problem was solved after re-optimization applying the corrected contours. The vacuum cushion and carbon-fiber couch contributed to increased skin doses. The tissue-equivalent-thickness method served as an effective way to correct the dose variations.

  17. Retinoids suppress cysteine-rich protein 61 (CCN1), a negative regulator of collagen homeostasis, in skin equivalent cultures and aged human skin in vivo.

    PubMed

    Quan, Taihao; Qin, Zhaoping; Shao, Yuan; Xu, Yiru; Voorhees, John J; Fisher, Gary J

    2011-07-01

    Alterations in connective tissue collagen are prominent features of both chronologically aged and photoaged (ageing because of sun exposure) human skin. These age-related abnormalities are mediated in part by cysteine-rich protein 61 (CCN1). CCN1 is elevated in the dermis of both chronologically aged and photoaged human skin in vivo and promotes aberrant collagen homeostasis by down-regulating type I collagen, the major structural protein in skin, and promoting collagen degradation. Vitamin A and its metabolites have been shown to improve chronologically aged and photoaged skin by promoting deposition of new collagen and preventing its degradation. Here, we investigated regulation of CCN1 expression by retinoids in skin equivalent cultures and chronologically aged and photoaged human skin in vivo. In skin equivalent cultures, all-trans retinoic acid (RA), the major bioactive form of vitamin A in skin, significantly increased type I procollagen and reduced collagenase (matrix metalloproteinases-1, MMP-1). Addition of recombinant human CCN1 to skin equivalent cultures significantly reduced type I procollagen and increased MMP-1. Importantly, RA significantly reduced CCN1 expression in skin equivalent cultures. Topical treatment with retinol (vitamin A, 0.4%) for 7days significantly reduced CCN1 mRNA and protein expression in both chronologically aged (80+years) and photoaged human skin in vivo, compared to vehicle-treated skin. These data indicate that the mechanism by which retinoids improve aged skin, through increased collagen production, involves down-regulation of CCN1.

  18. Expression and induction of cytochrome p450 isoenzymes in human skin equivalents.

    PubMed

    Neis, M M; Wendel, A; Wiederholt, T; Marquardt, Y; Joussen, S; Baron, J M; Merk, H F

    2010-01-01

    Organotypic skin models are frequently used for a wide range of applications and latterly also for dermatotoxicological studies. To evaluate their practicability for the investigation of xenobiotic metabolism in human skin we compared three types of organotypic skin models, acquired by purchase from different manufacturers, to a self-constructed in-house model with regard to cytochrome P450 (CYP) isoenzyme expression on mRNA and protein level and the inducibility of these enzymes by aryl hydrocarbon receptor ligands. To induce enzyme activity, models were treated with benzanthracene, liquor carbonis detergens, pix lithanthracis or dimethyl sulfoxide as a solvent control. RNA was isolated by phenol-chloroform extraction and purified. Gene expression patterns were studied by cDNA microarray analysis. Microarray data were confirmed by real-time PCR. For quality control of the models and to detect and localize enzyme expression, immunofluorescence staining was performed with antibodies against CYPs and structure proteins. The immunofluorescence staining demonstrated the regular structure of our models. We could provide evidence for the expression of CYP types 1A1, 1B1, 2E1, 2C and 3A5 in organotypic skin models. The expression of CYP1A1 and CYP1B1 was highly inducible by treatment with liquor carbonis detergens. The proof of the expression and inducibility of CYP enzymes in organotypic skin models suggests that skin equivalents are a valuable tool that can emulate CYP-dependent metabolism of drugs and other xenobiotics in human skin.

  19. The disappearance of the pfotzer-regener maximum in dose equivalent measurements in the stratosphere

    NASA Astrophysics Data System (ADS)

    Hands, A. D. P.; Ryden, K. A.; Mertens, C. J.

    2016-10-01

    The NASA Radiation Dosimetry Experiment (RaD-X) successfully deployed four radiation detectors on a high-altitude balloon for a period of approximately 20 h. One of these detectors was the RaySure in-flight monitor, which is a solid-state instrument designed to measure ionizing dose rates to aircrew and passengers. Data from RaySure on RaD-X show absorbed dose rates rising steadily as a function of altitude up to a peak at approximately 60,000 feet, known as the Pfotzer-Regener maximum. Above this altitude absorbed dose rates level off before showing a small decline as the RaD-X balloon approaches its maximum altitude of around 125,000 feet. The picture for biological dose equivalent, however, is very different. At high altitudes the fraction of dose from highly ionizing particles increases significantly. Dose from these particles causes a disproportionate amount of biological damage compared to dose from more lightly ionizing particles, and this is reflected in the quality factors used to calculate the dose equivalent quantity. By calculating dose equivalent from RaySure data, using coefficients derived from previous calibrations, we show that there is no peak in the dose equivalent rate at the Pfotzer-Regener maximum. Instead, the dose equivalent rate keeps increasing with altitude as the influence of dose from primary cosmic rays becomes increasingly important. This result has implications for high altitude aviation, space tourism and, due to its thinner atmosphere, the surface radiation environment on Mars.

  20. 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

  1. Longterm Monitoring of Ambient Dose Equivalent Rates at Aviation Altitudes

    NASA Astrophysics Data System (ADS)

    Möller, Thomas; Briese, J.; Burda, O.; Burmeister, S.; Glaßmeier, K. H.; Haag, K. H.; Heber, B.; Klages, T.; Langner, F.; Luchtenberg, F.; Matthiae, D.; Meier, M.; Nezel, M.; Reitz, G.; Wissmann, F.

    Galactic Cosmic Rays (GCRs) are high energetic charged particles, mainly protons and alpha-particles, originating from galactic sources and impinging on the Earth from all directions. The intensity of these particles is modulated by the solar activity, the Earth's magnetosphere and its atmosphere. Depending on the geomagnetic latitude only particles above certain cut-off rigidities can reach the top of the atmosphere. The cut-off rigidity is independent of the par-ticle sort; it is lowest over the magnetic poles and highest close to the equator. In the Earth's atmosphere, interactions of incident cosmic particles with atoms of the atmosphere's compo-nents cause not only deceleration or absorption of the primary particles but also production of new secondary particles which in turn can generate further particles. This results in a sec-ondary radiation field in the lower layers of the atmosphere, the composition and dose rate of which is dependent on altitude and magnetic latitude respectively. Beside this slowly varying background, solar energetic particle events (SPEs) may temporarily change this radiation field. One of the scientific goals of the RAMONA cooperation (RAdiation Monitoring ON board Aircraft) is to investigate the impact of SPEs on the radiation environment at flight altitudes. Although different models for such Space Weather effects have been developed, it is still im-possible to forecast the occurrence of a relevant SPE. Therefore, the permanent operation of appropriate dosimetric instruments onboard aircraft is pursued in order to gain knowledge for further model developments. Three NAVIDOS dosimetry systems (NAVIgation DOSimeter) developed by the RAMONA cooperation, have already been installed in aircraft. First results of the corresponding measurements will be presented.

  2. Radiation effect in mouse skin: Dose fractionation and wound healing

    SciTech Connect

    Gorodetsky, R.; Mou, X.D.; Fisher, D.R.; Taylor, J.M.; Withers, H.R. )

    1990-05-01

    Radiation induced dermal injury was measured by the gain in the physical strength of healing wounds in mouse skin. A sigmoid dose response for the inhibition of wound healing 14 days after surgery was found for single doses of X rays. The sparing of dermal damage from fractionation of the X-ray dose was quantified in terms of the alpha/beta ratio in the linear-quadratic (LQ) model, at a wide range of doses per fraction reaching as low as about 1 Gy. The fit and the appropriateness of the LQ model for the skin wound healing assay was examined with the use of the Fe-plot in which inverse total dose is plotted versus dose per fraction for wound strength isoeffects. The alpha/beta ratio of the skin was about 2.5 Gy (95% confidence of less than +/- 1 Gy) and was appropriate over a dose range of 1 Gy to about 8 Gy. The low alpha/beta value is typical for a late responding tissue. This assay, therefore, has the advantage of measuring and forecasting late radiation responses of the dermis within a short time after irradiation.

  3. 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.

  4. Calculation of equivalent dose for Auger electron emitting radionuclides distributed in human organs.

    PubMed

    Goddu, S M; Howell, R W; Rao, D V

    1996-01-01

    Radionuclides that emit Auger electrons can be extremely radiotoxic depending on the subcellular distribution of the radiochemical. Despite this, ICRP 60 provides no guidance in the calculation of equivalent dose H(T) for Auger electrons. The recent report by the American Association of Physicists in Medicine recommends a radiation weighting factor wR of 20 for stochastic effects caused by Auger electrons, along with a method of calculating the equivalent dose that takes into account the subcellular distribution of the radionuclide. In view of these recommendations, it is important to reevaluate equivalent doses from Auger electron emitters. The mean absorbed dose per unit cumulated activity (S-value) from Auger electrons and other radiations is calculated for ninety Auger-electron-emitting radionuclides distributed in human ovaries, testes and liver. Using these S-values, and the formalism given in the recent AAPM report, the dependence of the organ equivalent doses on subcellular distribution of the Auger electron emitters is examined. The results show an increase in the mean equivalent dose for Auger electron emitters when a significant fraction of the organ activity localizes in the DNA.

  5. Validation of the photon dose calculation model in the VARSKIN 4 skin dose computer code.

    PubMed

    Sherbini, Sami; Decicco, Joseph; Struckmeyer, Richard; Saba, Mohammad; Bush-Goddard, Stephanie

    2012-12-01

    An updated version of the skin dose computer code VARSKIN, namely VARSKIN 4, was examined to determine the accuracy of the photon model in calculating dose rates with different combinations of source geometry and radionuclides. The reference data for this validation were obtained by means of Monte Carlo transport calculations using MCNP5. The geometries tested included the zero volume sources point and disc, as well as the volume sources sphere and cylinder. Three geometries were tested using source directly on the skin, source off the skin with an absorber material between source and skin, and source off the skin with only an air gap between source and skin. The results of these calculations showed that the non-volume sources produced dose rates that were in very good agreement with the Monte Carlo calculations, but the volume sources resulted in overestimates of the dose rates compared with the Monte Carlo results by factors that ranged up to about 2.5. The results for the air gap showed poor agreement with Monte Carlo for all source geometries, with the dose rates overestimated in all cases. The conclusion was that, for situations where the beta dose is dominant, these results are of little significance because the photon dose in such cases is generally a very small fraction of the total dose. For situations in which the photon dose is dominant, use of the point or disc geometries should be adequate in most cases except those in which the dose approaches or exceeds an applicable limit. Such situations will often require a more accurate dose assessment and may require the use of methods such as Monte Carlo transport calculations.

  6. A reproducible laser-wounded skin equivalent model to study the effects of aging in vitro.

    PubMed

    Vaughan, Melville B; Ramirez, Ruben D; Brown, Spencer A; Yang, Jimmy C; Wright, Woodring E; Shay, Jerry W

    2004-01-01

    Skin aging involves both chronological and photoaging processes. The effects of these processes are often overlapping and include changes in both the stratified epithelium and the fibroblast-rich dermis. Wound healing is frequently delayed with aging and can result in scarring. A skin equivalent model can be used to study the role of cells and the extracellular matrix in the process of wound healing. Current studies using this model employ a full-thickness wound placed atop a nonwounded dermis to mimic a partial-thickness wound. However, a true reproducible partial-thickness wound model has yet to be described. In this study, we investigated whether a laser-wounded skin equivalent would be a useful partial-thickness wound healing model. Three lasers were compared for the ability to generate a reproducible wound: an erbium-YAG, a high-powered excimer, and a low-powered excimer laser. Reepithelialization ability was tested using newborn and adult skin keratinocytes, adult esophageal keratinocytes, and cdk4-overexpressing newborn keratinocytes. Keratinocyte compartmentalization and basement membrane formation were assessed by immunofluorescence. The erbium-YAG and high-powered excimer laser cut reproducible wounds but left the remaining surface either discolored due to thermal damage and/or ragged; keratinocytes were unable to migrate into the wound area. The low-powered excimer laser cut reproducible wounds, leaving the cut surface intact and visibly unaltered; keratinocytes reepithelialized the wound in a collagenase-dependent manner within 3 days; and return of compartmentalization and basement membrane occurred within 14 days. The laser-wounded skin equivalent is an adjustable, reproducible partial-thickness wound model where keratinocyte biology akin to in vivo can be studied, and will be useful to study the effects of aging on wound healing.

  7. Study of neutron dose equivalent at the HIRFL deep tumor therapy terminal

    NASA Astrophysics Data System (ADS)

    Xu, Jun-Kui; Su, You-Wu; Li, Wu-Yuan; Yan, Wei-Wei; Li, Zong-Qiang; Mao, Wang; Pang, Cheng-Guo; Xu, Chong

    2017-06-01

    The secondary neutron fields at the deep tumor therapy terminal at HIRFL (Heavy Ion Research Facility in Lanzhou) were investigated. The distributions of neutron ambient dose equivalent were measured with a FHT762 Wendi-II neutron ambient dose equivalent meter as 12C ions with energies of 165, 207, 270, and 350 MeV/u were bombarded on thick tissue-like targets. The thickness of targets used in the experiments was larger than the range of the carbon ions. The neutron spectra and dose equivalent were simulated by using FLUKA code, and the results agree well with the experimental data. The experiment results showed that the neutron dose produced by fragmentation reactions in tissue can be neglected in carbon-ion therapy, even considering their enhanced biological effectiveness. These results are also valuable for radiation protection, especially in the shielding design of high energy heavy ion medical machines.

  8. Neutron spectra and dose equivalents calculated in tissue for high-energy radiation therapy

    PubMed Central

    Kry, Stephen F.; Howell, Rebecca M.; Salehpour, Mohammad; Followill, David S.

    2009-01-01

    Neutrons are by-products of high-energy radiation therapy and a source of dose to normal tissues. Thus, the presence of neutrons increases a patient’s risk of radiation-induced secondary cancer. Although neutrons have been thoroughly studied in air, little research has been focused on neutrons at depths in the patient where radiosensitive structures may exist, resulting in wide variations in neutron dose equivalents between studies. In this study, we characterized properties of neutrons produced during high-energy radiation therapy as a function of their depth in tissue and for different field sizes and different source-to-surface distances (SSD). We used a previously developed Monte Carlo model of an accelerator operated at 18 MV to calculate the neutron fluences, energy spectra, quality factors, and dose equivalents in air and in tissue at depths ranging from 0.1 to 25 cm. In conjunction with the sharply decreasing dose equivalent with increased depth in tissue, the authors found that the neutron energy spectrum changed drastically as a function of depth in tissue. The neutron fluence decreased gradually as the depth increased, while the average neutron energy decreased sharply with increasing depth until a depth of approximately 7.5 cm in tissue, after which it remained nearly constant. There was minimal variation in the quality factor as a function of depth. At a given depth in tissue, the neutron dose equivalent increased slightly with increasing field size and decreasing SSD; however, the percentage depth-dose equivalent curve remained constant outside the primary photon field. Because the neutron dose equivalent, fluence, and energy spectrum changed substantially with depth in tissue, we concluded that when the neutron dose equivalent is being determined at a depth within a patient, the spectrum and quality factor used should be appropriate for depth rather than for in-air conditions. Alternately, an appropriate percent depth-dose equivalent curve should

  9. 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

    2016-07-01

    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. PACS number(s): 87

  10. 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.

  11. Exposure reductions encouraged by the determination of the effective dose equivalent for non-uniform exposures

    SciTech Connect

    Matheny, M.D.; Brown, C.G.; Dyer, S.G.

    1994-08-01

    DOE Order 5480.11 requires calculation of the effective dose equivalent (EDE) due to non-uniform radiation fields using ICRP-26 weighting factors. To comply with this requirement, Westinghouse Savannah River Company (WSRC) developed a simple dose calculation scheme based on a draft report by the External Dosimetry Working Group of the Health Physics Society Standards Committee. The calculations involved are fairly simple and provide a conservative dose estimate. The resulting EDE estimate provides a much better representation of the risk to the monitored individual than the more prevalent practice of assigning the highest measured dose. Details of the dose assessment methodology are included as an attachment.

  12. Characterization of a MOSkin detector for in vivo skin dose measurements during interventional radiology procedures

    SciTech Connect

    Safari, M. J.; Wong, J. H. D.; Ng, K. H.; Jong, W. L.; Cutajar, D. L.; Rosenfeld, A. B.

    2015-05-15

    Purpose: The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures. Methods: The calibration and reproducibility of the MOSkin detector and its dependency on different radiation beam qualities were carried out using RQR standard radiation qualities in free-in-air geometry. Studies of the other characterization parameters, such as the dose linearity and dependency on exposure angle, field size, frame rate, depth-dose, and source-to-surface distance (SSD), were carried out using a solid water phantom under a clinical x-ray unit. Results: The MOSkin detector showed good reproducibility (94%) and dose linearity (99%) for the dose range of 2 to 213 cGy. The sensitivity did not significantly change with the variation of SSD (±1%), field size (±1%), frame rate (±3%), or beam energy (±5%). The detector angular dependence was within ±5% over 360° and the dose recorded by the MOSkin detector in different depths of a solid water phantom was in good agreement with the Markus parallel plate ionization chamber to within ±3%. Conclusions: The MOSkin detector proved to be reliable when exposed to different field sizes, SSDs, depths in solid water, dose rates, frame rates, and radiation incident angles within a clinical x-ray beam. The MOSkin detector with water equivalent depth equal to 0.07 mm is a suitable detector for in vivo skin dosimetry during interventional radiology procedures.

  13. Shelf-life evaluation of bilayered human skin equivalent, MyDerm™.

    PubMed

    Seet, Wan Tai; Manira, Maarof; Maarof, Manira; Khairul Anuar, Khairoji; Chua, Kien-Hui; Ahmad Irfan, Abdul Wahab; Ng, Min Hwei; Aminuddin, Bin Saim; Ruszymah, Bt Hj Idrus

    2012-01-01

    Skin plays an important role in defense against infection and other harmful biological agents. Due to its fragile structure, skin can be easily damaged by heat, chemicals, traumatic injuries and diseases. An autologous bilayered human skin equivalent, MyDerm™, was engineered to provide a living skin substitute to treat critical skin loss. However, one of the disadvantages of living skin substitute is its short shelf-life, hence limiting its distribution worldwide. The aim of this study was to evaluate the shelf-life of MyDerm™ through assessment of cell morphology, cell viability, population doubling time and functional gene expression levels before transplantation. Skin samples were digested with 0.6% Collagenase Type I followed by epithelial cells dissociation with TrypLE Select. Dermal fibroblasts and keratinocytes were culture-expanded to obtain sufficient cells for MyDerm™ construction. MyDerm™ was constructed with plasma-fibrin as temporary biomaterial and evaluated at 0, 24, 48 and 72 hours after storage at 4°C for its shelf-life determination. The morphology of skin cells derived from MyDerm™ remained unchanged across storage times. Cells harvested from MyDerm™ after storage appeared in good viability (90.5%±2.7% to 94.9%±1.6%) and had short population doubling time (58.4±8.7 to 76.9±19 hours). The modest drop in cell viability and increased in population doubling time at longer storage duration did not demonstrate a significant difference. Gene expression for CK10, CK14 and COL III were also comparable between different storage times. In conclusion, MyDerm™ can be stored in basal medium at 4°C for at least 72 hours before transplantation without compromising its functionality.

  14. Natural background dose and radium equivalent measurements at Ikogosi warm spring, Nigeria.

    PubMed

    Isinkaye, M O; Ajayi, I R

    2006-01-01

    The natural background dose and the radium equivalent due to the natural radioactivity levels in rocks and sediments collected around Ikogosi warm spring, Nigeria, has been determined in this study using a highly sensitive HpGe detector. The mean activity concentration of (40)K, (226)Ra and (228)Ac were measured to be 585.50 +/- 17.40 Bq kg(-1), 66.91 +/- 5.23 Bq kg(-1) and 48.91 +/- 2.10 Bq kg(-1), respectively, in rock samples while in sediment samples the activity concentrations were found to be 113.89 +/- 5.64 Bq kg(-1) for (40)K, 21.47 +/- 5.14 Bq kg(-1) for (226)Ra and 14.20 +/- 1.07 Bq kg(-1) for (228)Ac. This mean values give rise to average absorbed dose rate of 85.87 nGy h(-1) at a distance of 1.0 m above the ground level and a mean human effective dose equivalent of 0.53 man Sv y(-1) for rock samples. A radium equivalent of 50.55 Bq kg(-1) was measured for the sediment samples. The radium equivalent value is far less than the 370 Bq kg(-1) limit for materials that can be used as building materials while the human effective dose equivalent falls below the world average background dose of 2.4 man Sv y(-1).

  15. Calculation of total effective dose equivalent and collective dose in the event of a LOCA in Bushehr Nuclear Power Plant.

    PubMed

    Raisali, G; Davilu, H; Haghighishad, A; Khodadadi, R; Sabet, M

    2006-01-01

    In this research, total effective dose equivalent (TEDE) and collective dose (CD) are calculated for the most adverse potential accident in Bushehr Nuclear Power Plant from the viewpoint of radionuclides release to the environment. Calculations are performed using a Gaussian diffusion model and a slightly modified version of AIREM computer code to adopt for conditions in Bushehr. The results are comparable with the final safety analysis report which used DOZAM code. Results of our calculations show no excessive dose in populated regions. Maximum TEDE is determined to be in the WSW direction. CD in the area around the nuclear power plant by a distance of 30 km (138 man Sv) is far below the accepted limits. Thyroid equivalent dose is also calculated for the WSW direction (maximum 25.6 mSv) and is below the limits at various distances from the reactor stack.

  16. Dose evaluation for skin and organ in hepatocellular carcinoma during angiographic procedure

    PubMed Central

    2013-01-01

    Purpose The purpose of this study is to evaluate the radiation dose in patients undergoing liver angiographic procedure and verify the usefulness of different dose measurements to prevent deterministic effects. Gafchromic film, MicroMOSFET data and DIAMENTOR device of the X-ray system were used to characterize the examined interventional radiology (IR) procedure. Materials and methods A liver embolization procedure, the SIRT (Selective Internal Radiation Therapy), was investigated. The exposure parameters from the DIAMENTOR as well as patient and geometrical data were registered. Entrance skin dose map obtained using Gafchromic film (ESDGAF) in a standard phantom as well as in 12 patients were used to calculate the maximum skin dose (MSDGAF). MicroMOSFETs were used to assess ESD in relevant points/areas. Moreover, the maximum value of five MicroMOSFETs array, due to the extension of treated area and to the relative distance of 2–3 cm of two adjacent MicroMOSFETs, was useful to predict the MSD without interfering with the clinical practice. PCXMC vers.1.5 was used to calculate effective dose (E) and equivalent dose (H). Results The mean dose-area product (DAPDIAMENTOR) for SIRT procedures was 166 Gycm2, although a wide range was observed. The mean MSDGAF for SIRT procedures was 1090 mGy, although a wide range was experienced. A correlation was found between the MSDGAF measured on a patient and the DAPDIAMENTOR value for liver embolizations. MOSFET and Gafchromic data were in agreement within 5% in homogeneous area and within 20% in high dose gradient regions. The mean equivalent dose in critical organs was 89.8 mSv for kidneys, 22.9 mSv for pancreas, 20.2 mSv for small intestine and 21.0 mSv for spleen. Whereas the mean E was 3.7 mSv (range: 0.5-13.7). Conclusions Gafchromic films result useful to study patient exposure and determine localization and amplitude of high dose skin areas to better predict the skin injuries. Then, DAPDIAMENTOR or MOSFET data

  17. UV doses and skin effects during psoriasis climate therapy

    NASA Astrophysics Data System (ADS)

    Randeberg, Lise L.; Hernandez-Palacios, Julio; Lilleeng, Mila; Nilsen, Lill Tove; Krogstad, Anne-Lene

    2011-03-01

    Psoriasis is a common autoimmune disease with inflammatory symptoms affecting skin and joints. One way of dealing with psoriasis is by controlled solar UV exposure treatment. However, this treatment should be optimized to get the best possible treatment effect and to limit negative side effects such as erythema and an increased risk of skin cancer. In this study 24 patients at Valle Marina Treatment Center in Gran Canaria were monitored throughout a treatment period of three weeks starting at the beginning of November. The total UV dose to the location was monitored by UV-meters placed on the roof of the treatment centere, and the patients wore individual film dosimeters throughout the treatment period. Skin parameters were accessed by reflection spectroscopy (400-850nm). This paper presents preliminary findings from the skin measurements in the visible part of the spectrum, such as blood oxygenation, erythema and melanin indexes. Reflection spectroscopy was found to be a good tool for such treatment monitoring.

  18. Metoprolol Dose Equivalence in Adult Men and Women Based on Gender Differences: Pharmacokinetic Modeling and Simulations

    PubMed Central

    Eugene, Andy R.

    2016-01-01

    Recent meta-analyses and publications over the past 15 years have provided evidence showing there are considerable gender differences in the pharmacokinetics of metoprolol. Throughout this time, there have not been any research articles proposing a gender stratified dose-adjustment resulting in an equivalent total drug exposure. Metoprolol pharmacokinetic data was obtained from a previous publication. Data was modeled using nonlinear mixed effect modeling using the MONOLIX software package to quantify metoprolol concentration–time data. Gender-stratified dosing simulations were conducted to identify equivalent total drug exposure based on a 100 mg dose in adults. Based on the pharmacokinetic modeling and simulations, a 50 mg dose in adult women provides an approximately similar metoprolol drug exposure to a 100 mg dose in adult men. PMID:28035289

  19. Barrier Properties of an N/TERT-Based Human Skin Equivalent

    PubMed Central

    van Drongelen, Vincent; Danso, Mogbekeloluwa O.; Mulder, Aat; Mieremet, Arnout; van Smeden, Jeroen

    2014-01-01

    Human skin equivalents (HSEs) can be considered a valuable tool to study aspects of human skin, including the skin barrier, or to perform chemical or toxicological screenings. HSEs are three-dimensional skin models that are usually established using primary keratinocytes and closely mimic human skin. The use of primary keratinocytes has several drawbacks, including a limited in vitro life span and large donor–donor variation. This makes them less favorable for in vitro toxicity screenings. Usage of an established keratinocyte cell line circumvents these drawbacks and enables the generation of easy-to-generate and reproducible HSEs, which can be used for pharmacological and/or toxicological screenings. For such screenings, a proper barrier function is required. In this study, we investigated the barrier properties of HSEs established with the keratinocyte cell line N/TERT (N-HSEs). N-HSEs showed comparable tissue morphology and expression of several epidermal proteins compared with HSEs established with primary keratinocytes. Our results clearly demonstrate that N-HSEs not only contain several stratum corneum (SC) barrier properties similar to HSEs, including the presence of the long periodicity phase and a comparable SC permeability, but also show some differences in lipid composition. Nonetheless, the similarities in barrier properties makes N/TERT cells a promising alternative for primary keratinocytes to generate HSEs. PMID:24819925

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

    SciTech Connect

    Kok, H. Petra; Crezee, Johannes; Franken, Nicolaas A.P.; Barendsen, Gerrit W.

    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 normal 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

  1. Evaluation of 3D-human skin equivalents for assessment of human dermal absorption of some brominated flame retardants.

    PubMed

    Abdallah, Mohamed Abou-Elwafa; Pawar, Gopal; Harrad, Stuart

    2015-11-01

    Ethical and technical difficulties inherent to studies in human tissues are impeding assessment of the dermal bioavailability of brominated flame retardants (BFRs). This is further complicated by increasing restrictions on the use of animals in toxicity testing, and the uncertainties associated with extrapolating data from animal studies to humans due to inter-species variations. To overcome these difficulties, we evaluate 3D-human skin equivalents (3D-HSE) as a novel in vitro alternative to human and animal testing for assessment of dermal absorption of BFRs. The percutaneous penetration of hexabromocyclododecanes (HBCD) and tetrabromobisphenol-A (TBBP-A) through two commercially available 3D-HSE models was studied and compared to data obtained for human ex vivo skin according to a standard protocol. No statistically significant differences were observed between the results obtained using 3D-HSE and human ex vivo skin at two exposure levels. The absorbed dose was low (less than 7%) and was significantly correlated with log Kow of the tested BFR. Permeability coefficient values showed increasing dermal resistance to the penetration of γ-HBCD>β-HBCD>α-HBCD>TBBPA. The estimated long lag times (>30 min) suggests that frequent hand washing may reduce human exposure to HBCDs and TBBPA via dermal contact.

  2. Effective dose equivalent to the operator in intra-oral dental radiography

    SciTech Connect

    de Haan, R.A.; van Aken, J. )

    1990-08-01

    The effective dose equivalent to the operator in intra-oral dental radiography has been determined. The exposure from a bitewing radiograph and periapical views of the left maxillary incisors and first molar was measured at nine heights and 16 positions, all 1 m from the patient. The effective dose equivalent was determined using data from ICRP 51 (International Commission on Radiological Protection: Data for Use in Protection Against External Radiation). The values presented are related to an exposure of 1 C kg-1 (3876 R) measured free in air at the tube-end. They thus constitute ratios which are not influenced by the sensitivity of the film or other detector used and form standard tables which permit the calculation of the effective dose equivalent in clinical situations.

  3. Application of solid state integrating dosemeters to the determination of biologically equivalent doses in space.

    PubMed

    Yasuda, H

    2002-01-01

    If the biological responses are well approximated by the efficiencies of solid-state integrating dosemeters (SSID), the biologically equivalent doses can be simply estimated using SSID. For demonstrating the applicability of this method to space radiation dosimetry, biologically equivalent doses for two biological endpoints (enzyme inactivation and cell survival) were evaluated in the 8.8 d Shuttle-Mir mission (STS-89) using three commercial thermoluminescence dosemeters: Mg2SiO4:Tb, BeO:Na and 7LiF:Mg,Ti. The approximate biologically equivalent doses at two positions in the Spacehab module were found to be significantly different for trypsin inactivation, whereas they were almost identical for mammalian cell survival.

  4. Effective dose equivalent to the operator in intra-oral dental radiography.

    PubMed

    de Haan, R A; van Aken, J

    1990-08-01

    The effective dose equivalent to the operator in intra-oral dental radiography has been determined. The exposure from a bitewing radiograph and periapical views of the left maxillary incisors and first molar was measured at nine heights and 16 positions, all 1 m from the patient. The effective dose equivalent was determined using data from ICRP 51 (International Commission on Radiological Protection: Data for Use in Protection Against External Radiation). The values presented are related to an exposure of 1 C kg-1 (3876 R) measured free in air at the tube-end. They thus constitute ratios which are not influenced by the sensitivity of the film or other detector used and form standard tables which permit the calculation of the effective dose equivalent in clinical situations.

  5. Reconstruction of chronic dose equivalents for Rongelap and Utirik residents: 1954 to 1980

    SciTech Connect

    Lessard, E T; Greenhouse, N A; Miltenberger, R P

    1980-10-01

    From June 1946 to August 1958, the US Department of Defense and Atomic Energy Commission conducted nuclear weapons tests in the Northern Marshall Islands. BRAVO, an aboveground test in the Castle series, resulted in radioactive fallout contaminating Rongelap and Utirik Atolls. On March 3, 1954, the inhabitants of these atolls were relocated until radiation exposure rates declined to acceptable levels. Environmental and personnel radiological monitoring programs were begun in the mid 1950's by Brookhaven National Laboratory to ensure that dose equivalents received or committed remained within US Federal Radiation Council Guidelines for members of the general public. Body burden and dose equivalent histories along with activity ingestion patterns post return are presented. Dosimetric methods, results, and internal dose equivalent distributions for subgroups of the population are also described.

  6. Verification of the VARSKIN beta skin dose calculation computer code.

    PubMed

    Sherbini, Sami; DeCicco, Joseph; Gray, Anita Turner; Struckmeyer, Richard

    2008-06-01

    The computer code VARSKIN is used extensively to calculate dose to the skin resulting from contaminants on the skin or on protective clothing covering the skin. The code uses six pre-programmed source geometries, four of which are volume sources, and a wide range of user-selectable radionuclides. Some verification of this code had been carried out before the current version of the code, version 3.0, was released, but this was limited in extent and did not include all the source geometries that the code is capable of modeling. This work extends this verification to include all the source geometries that are programmed in the code over a wide range of beta radiation energies and skin depths. Verification was carried out by comparing the doses calculated using VARSKIN with the doses for similar geometries calculated using the Monte Carlo radiation transport code MCNP5. Beta end-point energies used in the calculations ranged from 0.3 MeV up to 2.3 MeV. The results showed excellent agreement between the MCNP and VARSKIN calculations, with the agreement being within a few percent for point and disc sources and within 20% for other sources with the exception of a few cases, mainly at the low end of the beta end-point energies. The accuracy of the VARSKIN results, based on the work in this paper, indicates that it is sufficiently accurate for calculation of skin doses resulting from skin contaminations, and that the uncertainties arising from the use of VARSKIN are likely to be small compared with other uncertainties that typically arise in this type of dose assessment, such as those resulting from a lack of exact information on the size, shape, and density of the contaminant, the depth of the sensitive layer of the skin at the location of the contamination, the duration of the exposure, and the possibility of the source moving over various areas of the skin during the exposure period if the contaminant is on protective clothing.

  7. Dose equivalence for high-dose-rate to low-dose-rate intracavitary irradiation in the treatment of cancer of the uterine cervix

    SciTech Connect

    Akine, Y.; Tokita, N.; Ogino, T.; Kajiura, Y.; Tsukiyama, I.; Egawa, S. )

    1990-12-01

    By comparing the incidence of major radiation injury, we estimated doses clinically equivalent for high-dose-rate (HDR) to conventional low-dose-rate (LDR) intracavitary irradiation in patients with Stages IIb and IIIb cancer of the uterine cervix. We reviewed a total of 300 patients who were treated with external beam therapy to the pelvis (50 Gy in 5 weeks) followed either by low-dose-rate (253 patients) or high-dose-rate (47 patients) intracavitary treatment. The high-dose-rate intracavitary treatment was given 5 Gy per session to point A, 4 fractions in 2 weeks, with a total dose of 20 Gy. The low-dose-rate treatment was given with one or two application(s) delivering 11-52 Gy to the point A. The local control rates were similar in both groups. The incidence of major radiation injury requiring surgical intervention were 5.1% (13/253) and 4.3% (2/47) for low-dose-rate and high-dose-rate groups, respectively. The 4.3% incidence corresponded to 29.8 Gy with low-dose-rate irradiation, thus, it was concluded that the clinically equivalent dose for high-dose-rate irradiation was approximately 2/3 (20/29.8) of the dose used in low-dose-rate therapy.

  8. Calculation of Ambient (H*(10)) and Personal (Hp(10)) Dose Equivalent from a 252Cf Neutron Source

    SciTech Connect

    Traub, Richard J.

    2010-03-26

    The purpose of this calculation is to calculate the neutron dose factors for the Sr-Cf-3000 neutron source that is located in the 318 low scatter room (LSR). The dose factors were based on the dose conversion factors published in ICRP-21 Appendix 6, and the Ambient dose equivalent (H*(10)) and Personal dose equivalent (Hp(10)) dose factors published in ICRP Publication 74.

  9. Prediction analysis of dose equivalent responses of neutron dosemeters used at a MOX fuel facility.

    PubMed

    Tsujimura, N; Yoshida, T; Takada, C

    2011-07-01

    To predict how accurately neutron dosemeters can measure the neutron dose equivalent (rate) in MOX fuel fabrication facility work environments, the dose equivalent responses of neutron dosemeters were calculated by the spectral folding method. The dosemeters selected included two types of personal dosemeter, namely a thermoluminescent albedo neutron dosemeter and an electronic neutron dosemeter, three moderator-based neutron survey meters, and one special instrument called an H(p)(10) monitor. The calculations revealed the energy dependences of the responses expected within the entire range of neutron spectral variations observed in neutron fields at workplaces.

  10. 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.

  11. 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.

  12. An effective dose assessment technique with NORM added consumer products using skin-point source on computational human phantom.

    PubMed

    Yoo, Do Hyeon; Shin, Wook-Geun; Lee, Hyun Cheol; Choi, Hyun Joon; Testa, Mauro; Lee, Jae Kook; Yeom, Yeon Soo; Kim, Chan Hyeong; Min, Chul Hee

    2016-12-01

    The aim of this study is to develop the assessment technique of the effective dose by calculating the organ equivalent dose with a Monte Carlo (MC) simulation and a computational human phantom for the naturally occurring radioactive material (NORM) added consumer products. In this study, we suggests the method determining the MC source term based on the skin-point source enabling the convenient and conservative modeling of the various type of the products. To validate the skin-point source method, the organ equivalent doses were compared with that by the product modeling source of the realistic shape for the pillow, waist supporter, sleeping mattress etc. Our results show that according to the source location, the organ equivalent doses were observed as the similar tendency for both source determining methods, however, it was observed that the annual effective dose with the skin-point source was conservative than that with the modeling source with the maximum 3.3 times higher dose. With the assumption of the gamma energy of 1MeV and product activity of 1Bqg(-1), the annual effective doses of the pillow, waist supporter and sleeping mattress with skin-point source was 3.09E-16SvBq(-1)year(-1), 1.45E-15SvBq(-1)year(-1), and 2,82E-16SvBq(-1)year(-1), respectively, while the product modeling source showed 9.22E-17SvBq(-1)year(-1), 9.29E-16SvBq(-1)year(-1), and 8.83E-17SvBq(-1)year(-1), respectively. In conclusion, it was demonstrated in this study that the skin-point source method could be employed to efficiently evaluate the annual effective dose due to the usage of the NORM added consumer products. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Personal dose equivalent conversion coefficients for electrons to 1 Ge V.

    PubMed

    Veinot, K G; Hertel, N E

    2012-04-01

    In a previous paper, conversion coefficients for the personal dose equivalent, H(p)(d), for photons were reported. This note reports values for electrons calculated using similar techniques. The personal dose equivalent is the quantity used to approximate the protection quantity effective dose when performing personal dosemeter calibrations and in practice the personal dose equivalent is determined using a 30×30×15 cm slab-type phantom. Conversion coefficients to 1 GeV have been calculated for H(p)(10), H(p)(3) and H(p)(0.07) in the recommended slab phantom. Although the conversion coefficients were determined for discrete incident energies, analytical fits of the conversion coefficients over the energy range are provided using a similar formulation as in the photon results previously reported. The conversion coefficients for the personal dose equivalent are compared with the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological Protection guidance. Effects of eyewear on H(p)(3) are also discussed.

  14. Sex-specific tissue weighting factors for effective dose equivalent calculations

    SciTech Connect

    Xu, X.G.; Reece, W.D.

    1996-01-01

    The effective dose equivalent was defined in the International Commission on Radiological Protection Publication 26 in 1977 and later adopted by the U.S. Nuclear REgulatory Commission. To calculate organ doses and effective dose equivalent for external exposures using Monte Carlo simulations, sex-specific anthropomorphic phantoms and sex-specific weighting factors are always employed. This paper presents detailed mathematical derivation of a set of sex-specific tissue weighting factors and the conditions which the weighting factors must satisfy. Results of effective dose equivalent calculations using female and male phantoms exposed to monoenergetic photon beams of 0.08, 0.3, and 1.0 MeV are provided and compared with results published by other authors using different sex-specific weighting factors and phantoms. The results indicate that females always receive higher effective dose equivalent than males for the photon energies and geometries considered and that some published data may be wrong due to mistakes in deriving the sex-specific weighting factors. 17 refs., 2 figs., 2 tabs.

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

    SciTech Connect

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

    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 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 {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).

  16. Mechanical Stretch on Human Skin Equivalents Increases the Epidermal Thickness and Develops the Basement Membrane

    PubMed Central

    Tokuyama, Eijiro; Nagai, Yusuke; Takahashi, Ken; Kimata, Yoshihiro; Naruse, Keiji

    2015-01-01

    All previous reports concerning the effect of stretch on cultured skin cells dealt with experiments on epidermal keratinocytes or dermal fibroblasts alone. The aim of the present study was to develop a system that allows application of stretch stimuli to human skin equivalents (HSEs), prepared by coculturing of these two types of cells. In addition, this study aimed to analyze the effect of a stretch on keratinization of the epidermis and on the basement membrane. HSEs were prepared in a gutter-like structure created with a porous silicone sheet in a silicone chamber. After 5-day stimulation with stretching, HSEs were analyzed histologically and immunohistologically. Stretch-stimulated HSEs had a thicker epidermal layer and expressed significantly greater levels of laminin 5 and collagen IV/VII in the basal layer compared with HSEs not subjected to stretch stimulation. Transmission electron microscopy revealed that the structure of the basement membrane was more developed in HSEs subjected to stretching. Our model may be relevant for extrapolating the effect of a stretch on the skin in a state similar to an in vivo system. This experimental system may be useful for analysis of the effects of stretch stimuli on skin properties and wound healing and is also expected to be applicable to an in vitro model of a hypertrophic scar in the future. PMID:26528823

  17. Mechanical Stretch on Human Skin Equivalents Increases the Epidermal Thickness and Develops the Basement Membrane.

    PubMed

    Tokuyama, Eijiro; Nagai, Yusuke; Takahashi, Ken; Kimata, Yoshihiro; Naruse, Keiji

    2015-01-01

    All previous reports concerning the effect of stretch on cultured skin cells dealt with experiments on epidermal keratinocytes or dermal fibroblasts alone. The aim of the present study was to develop a system that allows application of stretch stimuli to human skin equivalents (HSEs), prepared by coculturing of these two types of cells. In addition, this study aimed to analyze the effect of a stretch on keratinization of the epidermis and on the basement membrane. HSEs were prepared in a gutter-like structure created with a porous silicone sheet in a silicone chamber. After 5-day stimulation with stretching, HSEs were analyzed histologically and immunohistologically. Stretch-stimulated HSEs had a thicker epidermal layer and expressed significantly greater levels of laminin 5 and collagen IV/VII in the basal layer compared with HSEs not subjected to stretch stimulation. Transmission electron microscopy revealed that the structure of the basement membrane was more developed in HSEs subjected to stretching. Our model may be relevant for extrapolating the effect of a stretch on the skin in a state similar to an in vivo system. This experimental system may be useful for analysis of the effects of stretch stimuli on skin properties and wound healing and is also expected to be applicable to an in vitro model of a hypertrophic scar in the future.

  18. Fructose 1, 6-diphosphate regulates desmosomal proteins and collagen fibres in human skin equivalents.

    PubMed

    Choi, Hyun; Yang, Seung Ha; Bae, Il-Hong; Park, Ju-Yearl; Kim, Hyoung-June; Noh, Minsoo; Lee, Tae Ryong; Shin, Dong Wook

    2013-12-01

    We previously reported that fructose 1,6-diphosphate (FDP), a glycolytic metabolite, alleviates ultraviolet B-induced oxidative skin damage. Here, we further examined the effects of FDP on skin. FDP decreased the number of desmosomes, whereas it increased collagen fibres in skin equivalents (SEs). FDP significantly decreased the expression of corneodesmosomal components such as desmoglein 1 (DSG1), desmocollin 1 (DSC1) and corneodesmosin (CDSN), and desquamation-related proteases, kallikrein 5 (KLK 5) and kallikrein 7 (KLK7) in normal human epidermal keratinocytes (NHEKs). In addition, FDP treatment increased the phosphorylation of p38 MAPK, but the decreased expression of corneodesmosomal components is not recovered by the treatment of p38 MAPK inhibitors. Interestingly, FDP diminished the amplitude of Ca(2+) fluxes through down-regulation of SERCA2. Taken together, these results suggested that FDP induced a decrease in desmosomes and an increase in collagen fibres similar to the process of chemical peeling, the most common treatments for ageing skin.

  19. 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.

  20. Calculation of personal dose equivalent for positron-emitting radionuclides using Monte Carlo code EGS5.

    PubMed

    Kato, T; Aoki, K; Yokoyama, S; Ejiri, K; Minami, K; Yashima, H; Taniguchi, A; Nakamura, T; Hirayama, H

    2011-07-01

    The conversion coefficients, H'(d,α)/Φ, for monoenergetic positrons and positron-emitting radionuclides were calculated by using the user code UCICRPM of the Monte Carlo code EGS5 to estimate the radiation dose for medical staff involved in positron emission tomography examinations. From these coefficients, the dose equivalent rates per unit activity at 0.07 and 10 mm depths in a soft tissue for a straight-line source of 2-deoxy-2-[(18)F]fluoro-d-glucose ((18)F-FDG) were calculated by using the developed user code UCF18DOSE. The dose equivalent rates per unit activity at 0.07 and 10 mm depths were measured by using a personal dosemeter (DOSE(3)) under the same conditions as those considered in the calculation. The calculated dose equivalent rates per unit activity at 0.07 and 10 mm depths were 0.116 and 0.0352 pSv min(-1) Bq(-1), respectively, at 20 cm from the (18)F-FDG injection tube.

  1. Limitations of the TG-43 formalism for skin high-dose-rate brachytherapy dose calculations

    SciTech Connect

    Granero, Domingo; Perez-Calatayud, Jose; Vijande, Javier; Ballester, Facundo; Rivard, Mark J.

    2014-02-15

    Purpose: In skin high-dose-rate (HDR) brachytherapy, sources are located outside, in contact with, or implanted at some depth below the skin surface. Most treatment planning systems use the TG-43 formalism, which is based on single-source dose superposition within an infinite water medium without accounting for the true geometry in which conditions for scattered radiation are altered by the presence of air. The purpose of this study is to evaluate the dosimetric limitations of the TG-43 formalism in HDR skin brachytherapy and the potential clinical impact. Methods: Dose rate distributions of typical configurations used in skin brachytherapy were obtained: a 5 cm × 5 cm superficial mould; a source inside a catheter located at the skin surface with and without backscatter bolus; and a typical interstitial implant consisting of an HDR source in a catheter located at a depth of 0.5 cm. Commercially available HDR{sup 60}Co and {sup 192}Ir sources and a hypothetical {sup 169}Yb source were considered. The Geant4 Monte Carlo radiation transport code was used to estimate dose rate distributions for the configurations considered. These results were then compared to those obtained with the TG-43 dose calculation formalism. In particular, the influence of adding bolus material over the implant was studied. Results: For a 5 cm × 5 cm{sup 192}Ir superficial mould and 0.5 cm prescription depth, dose differences in comparison to the TG-43 method were about −3%. When the source was positioned at the skin surface, dose differences were smaller than −1% for {sup 60}Co and {sup 192}Ir, yet −3% for {sup 169}Yb. For the interstitial implant, dose differences at the skin surface were −7% for {sup 60}Co, −0.6% for {sup 192}Ir, and −2.5% for {sup 169}Yb. Conclusions: This study indicates the following: (i) for the superficial mould, no bolus is needed; (ii) when the source is in contact with the skin surface, no bolus is needed for either {sup 60}Co and {sup 192}Ir. For

  2. Limitations of the TG-43 formalism for skin high-dose-rate brachytherapy dose calculations

    SciTech Connect

    Granero, Domingo; Perez-Calatayud, Jose; Vijande, Javier; Ballester, Facundo; Rivard, Mark J.

    2014-02-15

    Purpose: In skin high-dose-rate (HDR) brachytherapy, sources are located outside, in contact with, or implanted at some depth below the skin surface. Most treatment planning systems use the TG-43 formalism, which is based on single-source dose superposition within an infinite water medium without accounting for the true geometry in which conditions for scattered radiation are altered by the presence of air. The purpose of this study is to evaluate the dosimetric limitations of the TG-43 formalism in HDR skin brachytherapy and the potential clinical impact. Methods: Dose rate distributions of typical configurations used in skin brachytherapy were obtained: a 5 cm × 5 cm superficial mould; a source inside a catheter located at the skin surface with and without backscatter bolus; and a typical interstitial implant consisting of an HDR source in a catheter located at a depth of 0.5 cm. Commercially available HDR{sup 60}Co and {sup 192}Ir sources and a hypothetical {sup 169}Yb source were considered. The Geant4 Monte Carlo radiation transport code was used to estimate dose rate distributions for the configurations considered. These results were then compared to those obtained with the TG-43 dose calculation formalism. In particular, the influence of adding bolus material over the implant was studied. Results: For a 5 cm × 5 cm{sup 192}Ir superficial mould and 0.5 cm prescription depth, dose differences in comparison to the TG-43 method were about −3%. When the source was positioned at the skin surface, dose differences were smaller than −1% for {sup 60}Co and {sup 192}Ir, yet −3% for {sup 169}Yb. For the interstitial implant, dose differences at the skin surface were −7% for {sup 60}Co, −0.6% for {sup 192}Ir, and −2.5% for {sup 169}Yb. Conclusions: This study indicates the following: (i) for the superficial mould, no bolus is needed; (ii) when the source is in contact with the skin surface, no bolus is needed for either {sup 60}Co and {sup 192}Ir. For

  3. Estimation of organ dose equivalents from residents of radiation-contaminated buildings with Rando phantom measurements.

    PubMed

    Lee, J S; Dong, S L; Wu, T H

    1999-05-01

    Since August 1996, a dose reconstruction model has been conducted with thermoluminescent dosimeter (TLD)-embedded chains, belts and badges for external dose measurements on the residents in radiation-contaminated buildings. The TLD dosimeters, worn on the front of the torso, would not be adequate for dose measurement in cases when the radiation is anisotropic or the incident angles of radiation sources are not directed in the front-to-back direction. The shielding and attenuation by the body would result in the dose equivalent estimation being somewhat skewed. An organ dose estimation method with a Rando phantom under various exposure geometries is proposed. The conversion factors, obtained from the phantom study, may be applicable to organ dose estimations for residents in the contaminated buildings if the incident angles correspond to the phantom simulation results. There is a great demand for developing a mathematical model or Monte Carlo calculation to deal with complicated indoor layout geometry problems involving ionizing radiation. Further research should be directed toward conducting laboratory simulation by investigating the relationship between doses delivered from multiple radiation sources. It is also necessary to collaborate with experimental biological dosimetry, such as chromosome aberration analysis, fluorescence in situ hybridization (FISH) and retrospective ESR-dosimetry with teeth, applied to the residents, so that the organ dose equivalent estimations may be more reliable for radio-epidemiological studies.

  4. Estimation of Radiobiologic Parameters and Equivalent Radiation Dose of Cytotoxic Chemotherapy in Malignant Glioma

    SciTech Connect

    Jones, Bleddyn . E-mail: b.jones.1@bham.ac.uk; Sanghera, Paul

    2007-06-01

    Purpose: To determine the radiobiologic parameters for high-grade gliomas. Methods and Materials: The biologic effective dose concept is used to estimate the {alpha}/{beta} ratio and K (dose equivalent for tumor repopulation/d) for high-grade glioma patients treated in a randomized fractionation trial. The equivalent radiation dose of temozolomide (Temodar) chemotherapy was estimated from another randomized study. The method assumes that the radiotherapy biologic effective dose is proportional to the adjusted radiotherapy survival duration of high-grade glioma patients. Results: The median tumor {alpha}/{beta} and K estimate is 9.32 Gy and 0.23 Gy/d, respectively. Using the published surviving fraction after 2-Gy exposure (SF{sub 2}) data, and the above {alpha}/{beta} ratio, the estimated median {alpha} value was 0.077 Gy{sup -1}, {beta} was 0.009 Gy{sup -2}, and the cellular doubling time was 39.5 days. The median equivalent biologic effective dose of temozolomide was 11.03 Gy{sub 9.3} (equivalent to a radiation dose of 9.1 Gy given in 2-Gy fractions). Random sampling trial simulations based on a cure threshold of 70 Gy in high-grade gliomas have shown the potential increase in tumor cure with dose escalation. Partial elimination of hypoxic cells (by chemical hypoxic cell sensitizers or carbon ion therapy) has suggested that considerable gains in tumor control, which are further supplemented by temozolomide, are achievable. Conclusion: The radiobiologic parameters for human high-grade gliomas can be estimated from clinical trials and could be used to inform future clinical trials, particularly combined modality treatments with newer forms of radiotherapy. Other incurable cancers should be studied using similar radiobiologic analysis.

  5. Verification of Calculated Skin Doses in Postmastectomy Helical Tomotherapy

    SciTech Connect

    Ito, Shima; Parker, Brent C.; Levine, Renee; Sanders, Mary Ella; Fontenot, Jonas; Gibbons, John; Hogstrom, Kenneth

    2011-10-01

    Purpose: To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). Methods and Materials: In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi.Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. Results: The mean difference and standard error of the mean difference between measurement and calculation for the scar measurements was -1.8% {+-} 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% {+-} 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% {+-} 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. Conclusions: The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%.

  6. Verification of calculated skin doses in postmastectomy helical tomotherapy.

    PubMed

    Ito, Shima; Parker, Brent C; Levine, Renee; Sanders, Mary Ella; Fontenot, Jonas; Gibbons, John; Hogstrom, Kenneth

    2011-10-01

    To verify the accuracy of calculated skin doses in helical tomotherapy for postmastectomy radiation therapy (PMRT). In vivo thermoluminescent dosimeters (TLDs) were used to measure the skin dose at multiple points in each of 14 patients throughout the course of treatment on a TomoTherapy Hi·Art II system, for a total of 420 TLD measurements. Five patients were evaluated near the location of the mastectomy scar, whereas 9 patients were evaluated throughout the treatment volume. The measured dose at each location was compared with calculations from the treatment planning system. The mean difference and standard error of the mean difference between measurement and calculation for the scar measurements was -1.8% ± 0.2% (standard deviation [SD], 4.3%; range, -11.1% to 10.6%). The mean difference and standard error of the mean difference between measurement and calculation for measurements throughout the treatment volume was -3.0% ± 0.4% (SD, 4.7%; range, -18.4% to 12.6%). The mean difference and standard error of the mean difference between measurement and calculation for all measurements was -2.1% ± 0.2% (standard deviation, 4.5%: range, -18.4% to 12.6%). The mean difference between measured and calculated TLD doses was statistically significant at two standard deviations of the mean, but was not clinically significant (i.e., was <5%). However, 23% of the measured TLD doses differed from the calculated TLD doses by more than 5%. The mean of the measured TLD doses agreed with TomoTherapy calculated TLD doses within our clinical criterion of 5%. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. SU-E-T-388: Evaluation of Electronic Brachytherapy Dose Distributions in Tissue Equivalent Materials

    SciTech Connect

    Johnson, M; Ahmad, S; Johnson, D

    2015-06-15

    Purpose: To study the measured and calculated dose distributions for electronic brachytherapy (EBT) in various tissue equivalent homogenous materials. Methods: Calculated dose distributions in water were generated using published TG-43 parameters in Varian BrachyVision software for a 50 kVp, 50 cm Xoft source. Dose distributions were measured within a 3D-scanning tank using dosimeters including: PTW 0.125 cc, pin-point, and parallel-plate ion chambers, Sun Nuclear “Edge” diode and Gafchromic EBT3 film. Multi-channel film dosimetry was used in film analysis. EBT3 film curves were calibrated via radial dose comparison to both independently measured and published data. The resulting film calibration was utilized to measure dose distributions created by titanium filtered source utilized in clinical brachytherapy applications. Data was collected within homogenous PMMA, vinyl, polystyrene, paraffin, and water-equivalent plastic phantoms. Results: Ion-chamber data was corrected to effective points of measurement and normalized prior to comparison between calculated and measured dose distributions. Measurements made in water and water equivalent materials compared well with results from treatment planning software. The maximum percent differences (relative to water) observed between 1 cm and 3.5 cm depth from source for each of the phantom materials are as follows: PMMA 35%, polystyrene 41%, plastic-water 23%, vinyl 115%, and paraffin 46%. Conclusion: The increased probability of photoelectric interactions occurring within the patient during electronic brachytherapy will emphasize the radiological differences between varying human tissues in dose deposition. These differences can Result in clinically significant dose perturbations and it is therefore recommended to move to a model based dose calculation, as outlined in TG-186, to improve the dosimetric accuracy of low energy EBT.

  8. Rituximab in severe skin diseases: target, disease, and dose

    PubMed Central

    Bennett, Daniel D; Ohanian, Maro; Cable, Christian T

    2010-01-01

    New clinical indications for rituximab seem to appear every day. This review will trace the use of this monoclonal antibody from lymphoid malignancy, to classic autoimmune disease, and specifically severe autoimmune skin diseases. The history leading to different dosing schema with associated pharmacokinetic data will be discussed. A case of livedoid vasculopathy (atrophie blanche) responding to rituximab will illustrate how the response to therapy can help to elucidate previously obscure pathophysiology. PMID:22291497

  9. Evaluation of dermal-epidermal skin equivalents ('composite-skin') of human keratinocytes in a collagen-glycosaminoglycan matrix(Integra artificial skin).

    PubMed

    Kremer, M; Lang, E; Berger, A C

    2000-09-01

    Integra artificial skin (Integra LifeSciences Corp., Plainsboro, NJ, USA) is a dermal template consisting of bovine collagen, chondroitin-6-sulphate and a silastic membrane manufactured as Integra. This product has gained widespread use in the clinical treatment of third degree burn wounds and full thickness skin defects of different aetiologies. The product was designed to significantly reduce the time needed to achieve final wound closure in the treatment of major burn wounds, to optimise the sparse autologous donor skin resources and to improve the durable mechanical quality of the skin substitute. The clinical procedure requires two stages. The first step creates a self neodermis, the second creates a self epidermis on the neodermis. However, it is desirable to cover major burn wounds early in a single step by a skin substitute consisting of a dermal equivalent seeded in vitro with autologous keratinocytes ('composite-skin') out of which a full thickness skin develops in vivo.The goal of this experimental study was to develop a method to integrate human keratinocytes in homogeneous distribution and depth into Integra Artificial Skin. The seeded cell-matrix composites were grafted onto athymic mice in order to evaluate their potential to reconstitute a human epidermis in vivo. We were able to demonstrate that the inoculated human keratinocytes reproducibly displayed a homogeneous pattern of distribution, adherence, proliferation and confluence. The cell-matrix composites grafted in this model exhibited good wound adherence, complete healing, minor wound contraction and had the potential to reconstitute an elastic, functional and durable human skin. Histologically we were able to show that the inoculated human keratinocytes in vivo colonised the matrix in a histomorphologically characteristic epidermal pattern (keratomorula, keratinocyte bubbling) and developed a persisting, stratified, keratinising epidermis which immunohistologically proved to be of human

  10. A pilot study of the photoprotective effect of almond phytochemicals in a 3D human skin equivalent

    USDA-ARS?s Scientific Manuscript database

    UV exposure causes oxidative stress, inflammation, erythema, and skin cancer. Alpha-Tocopherol (AT) and polyphenols (AP) present in almonds may serve as photoprotectants. Our objectives were to assess the feasibility of using a 3D human skin equivalent (HSE) in photoprotectant research and to deter...

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

    SciTech Connect

    Shinn, J.L.; Wilson, J.W.; Nealy, J.E.

    1990-04-01

    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.

  12. 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.

  13. Scattered neutron dose equivalent from an active scanning proton beam delivery system.

    PubMed

    Hecksel, Draik; Sandison, George A; Farr, Jonathan B; Edwards, Andrew C

    2007-12-01

    A study of neutron production from a novel active scanning proton beam delivery system at the Midwest Proton Radiotherapy Institute (MPRI) has been performed. The neutron dose equivalent was determined using a neutron rem (roentgen equivalent in man) detector which has an upper energy limit of 10 MeV. Measurement were taken at 0, 45, and 90 degrees from the proton beam central axis and for various proton beam energies (127-208 MeV) and scanned field sizes (25-144 cm2). The maximum neutron dose observed was 0.43 mSv / (proton treatment Gy) at 90 degrees from the beam axis for a beam energy of 208.4 MeV and a scanned field size of 144 cm2. It is still possible to further mitigate this secondary neutron dose during treatment by optimizing parameters within the treatment nozzle and using shielding.

  14. Characterization of MOSkin detector for in vivo skin dose measurement during megavoltage radiotherapy.

    PubMed

    Jong, Wei Loong; Wong, Jeannie Hsiu Ding; Ung, Ngie Min; Ng, Kwan Hoong; Ho, Gwo Fuang; Cutajar, Dean L; Rosenfeld, Anatoly B

    2014-09-08

    In vivo dosimetry is important during radiotherapy to ensure the accuracy of the dose delivered to the treatment volume. A dosimeter should be characterized based on its application before it is used for in vivo dosimetry. In this study, we characterize a new MOSFET-based detector, the MOSkin detector, on surface for in vivo skin dosimetry. The advantages of the MOSkin detector are its water equivalent depth of measurement of 0.07 mm, small physical size with submicron dosimetric volume, and the ability to provide real-time readout. A MOSkin detector was calibrated and the reproducibility, linearity, and response over a large dose range to different threshold voltages were determined. Surface dose on solid water phantom was measured using MOSkin detector and compared with Markus ionization chamber and GAFCHROMIC EBT2 film measurements. Dependence in the response of the MOSkin detector on the surface of solid water phantom was also tested for different (i) source to surface distances (SSDs); (ii) field sizes; (iii) surface dose; (iv) radiation incident angles; and (v) wedges. The MOSkin detector showed excellent reproducibility and linearity for dose range of 50 cGy to 300 cGy. The MOSkin detector showed reliable response to different SSDs, field sizes, surface, radiation incident angles, and wedges. The MOSkin detector is suitable for in vivo skin dosimetry.

  15. Comparison of the neutron ambient dose equivalent and ambient absorbed dose calculations with different GEANT4 physics lists

    NASA Astrophysics Data System (ADS)

    Ribeiro, Rosane Moreira; Souza-Santos, Denison

    2017-10-01

    A comparison between neutron physics lists given by GEANT4, is made in the calculation of the ambient dose equivalent, and ambient absorbed dose, per fluence conversion coefficients (H* (10) / ϕ and D* (10) / ϕ) for neutrons in the range of 10-9 MeV to 15 MeV. Physics processes are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles. Results obtained for QBBC, QGSP_BERT, QGSP_BIC and Neutron High Precision physics lists are compared with values published in ICRP 74 and previously published articles. Neutron high precision physics lists showed the best results in the studied energy range.

  16. Estimation of radiation-induced cancer from three-dimensional dose distributions: Concept of organ equivalent dose

    SciTech Connect

    Schneider, Uwe . E-mail: uwe.schneider@psi.ch; Zwahlen, Daniel; Ross, Dieter; Kaser-Hotz, Barbara

    2005-04-01

    Purpose: Estimates of secondary cancer risk after radiotherapy are becoming more important for comparative treatment planning. Modern treatment planning systems provide accurate three-dimensional dose distributions for each individual patient. These data open up new possibilities for more precise estimates of secondary cancer incidence rates in the irradiated organs. We report a new method to estimate organ-specific radiation-induced cancer incidence rates. The concept of an organ equivalent dose (OED) for radiation-induced cancer assumes that any two dose distributions in an organ are equivalent if they cause the same radiation-induced cancer incidence. Methods and Materials: The two operational parameters of the OED concept are the organ-specific cancer incidence rate at low doses, which is taken from the data of the atomic bomb survivors, and cell sterilization at higher doses. The effect of cell sterilization in various organs was estimated by analyzing the secondary cancer incidence data of patients with Hodgkin's disease who were treated with radiotherapy in between 1962 and 1993. The radiotherapy plans used at the time the patients had been treated were reconstructed on a fully segmented whole body CT scan. The dose distributions were calculated in individual organs for which cancer incidence data were available. The model parameter that described cell sterilization was obtained by analyzing the dose and cancer incidence rates for the individual organs. Results: We found organ-specific cell radiosensitivities that varied from 0.017 for the mouth and pharynx up to 1.592 for the bladder. Using the two model parameters (organ-specific cancer incidence rate and the parameter characterizing cell sterilization), the OED concept can be applied to any three-dimensional dose distribution to analyze cancer incidence. Conclusion: We believe that the concept of OED presented in this investigation represents a first step in assessing the potential risk of secondary

  17. Effects of erythropoietin in skin wound healing are dose related.

    PubMed

    Sorg, Heiko; Krueger, Christian; Schulz, Torsten; Menger, Michael D; Schmitz, Frank; Vollmar, Brigitte

    2009-09-01

    The hematopoietic growth factor erythropoietin (EPO) attracts attention due to its all-tissue-protective pleiotropic properties. We studied the effect of EPO on dermal regeneration using intravital microscopy in a model of full dermal thickness wounds in the skin-fold chamber of hairless mice. Animals received repetitive low doses or high doses of EPO (RLD-EPO or RHD-EPO) or a single high dose of EPO (SHD-EPO). SHD-EPO accelerated wound epithelialization, reduced wound cellularity, and induced maturation of newly formed microvascular networks. In contrast, RHD-EPO impaired the healing process, as indicated by delayed epithelialization, high wound cellularity, and lack of maturation of microvascular networks. Also, RHD-EPO caused an excessive erythrocyte mass and rheological malfunction, further deteriorating vessel and tissue maturation. Moreover, RHD-EPO altered fibroblast and keratinocyte migration in vitro, while both cell types exposed to RLD-EPO, and, in particular, to SHD-EPO showed accelerated wound scratch closure. In summary, our data show that a single application of a high dose of EPO accelerates and improves skin wound healing.

  18. Deuterons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2011-01-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons ((2)H(+)) in the energy range 10 MeV-1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by <3%. The greatest difference, 47%, occurred at 30 MeV.

  19. 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.

  20. Estimates of internal-dose equivalent from inhalation and ingestion of selected radionuclides

    SciTech Connect

    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 represented 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.

  1. Software for the estimation of organ equivalent and effective doses from diagnostic radiology procedures.

    PubMed

    Osei, Ernest K; Barnett, Rob

    2009-09-01

    Diagnostic radiological imaging such as conventional radiography, fluoroscopy and computed tomography (CT) examinations will continue to provide tremendous benefits in modern healthcare. The benefit derived by the patient should far outweigh the risk associated with a properly conducted imaging examination. Nonetheless, it is very important to be able to quantify the risk associated with any radiological examination of patients, and effective dose has been considered a useful indicator of patient exposure. Quantification of the risks associated with radiological imaging is very important as such information will be helpful to physicians and their patients for comparing risks from various imaging examinations and for making informed decisions whenever there is a need for any radiological imaging. The determination of equivalent and effective doses in diagnostic radiology is of interest as a basis for estimates of risk from medical exposures. In this paper we describe a simple computer program OrgDose, which calculates the doses to 27 organs in the body and then calculates the organ equivalent and effective doses and the risk from various procedures in the radiology department including conventional radiography, fluoroscopy and computed tomography examinations. The program will be a useful tool for the medical and paramedical personnel who are involved with assessing organ and effective doses and risks from diagnostic radiology procedures.

  2. Comparison of dose calculation algorithms in slab phantoms with cortical bone equivalent heterogeneities

    SciTech Connect

    Carrasco, P.; Jornet, N.; Duch, M. A.; Panettieri, V.; Weber, L.; Eudaldo, T.; Ginjaume, M.; Ribas, M.

    2007-08-15

    To evaluate the dose values predicted by several calculation algorithms in two treatment planning systems, Monte Carlo (MC) simulations and measurements by means of various detectors were performed in heterogeneous layer phantoms with water- and bone-equivalent materials. Percentage depth doses (PDDs) were measured with thermoluminescent dosimeters (TLDs), metal-oxide semiconductor field-effect transistors (MOSFETs), plane parallel and cylindrical ionization chambers, and beam profiles with films. The MC code used for the simulations was the PENELOPE code. Three different field sizes (10x10, 5x5, and 2x2 cm{sup 2}) were studied in two phantom configurations and a bone equivalent material. These two phantom configurations contained heterogeneities of 5 and 2 cm of bone, respectively. We analyzed the performance of four correction-based algorithms and one based on convolution superposition. The correction-based algorithms were the Batho, the Modified Batho, the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system (TPS), and the Helax-TMS Pencil Beam from the Helax-TMS (Nucletron) TPS. The convolution-superposition algorithm was the Collapsed Cone implemented in the Helax-TMS. All the correction-based calculation algorithms underestimated the dose inside the bone-equivalent material for 18 MV compared to MC simulations. The maximum underestimation, in terms of root-mean-square (RMS), was about 15% for the Helax-TMS Pencil Beam (Helax-TMS PB) for a 2x2 cm{sup 2} field inside the bone-equivalent material. In contrast, the Collapsed Cone algorithm yielded values around 3%. A more complex behavior was found for 6 MV where the Collapsed Cone performed less well, overestimating the dose inside the heterogeneity in 3%-5%. The rebuildup in the interface bone-water and the penumbra shrinking in high-density media were not predicted by any of the calculation algorithms except the Collapsed Cone, and only the MC simulations matched the experimental values

  3. Comparison of dose calculation algorithms in slab phantoms with cortical bone equivalent heterogeneities.

    PubMed

    Carrasco, P; Jornet, N; Duch, M A; Panettieri, V; Weber, L; Eudaldo, T; Ginjaume, M; Ribas, M

    2007-08-01

    To evaluate the dose values predicted by several calculation algorithms in two treatment planning systems, Monte Carlo (MC) simulations and measurements by means of various detectors were performed in heterogeneous layer phantoms with water- and bone-equivalent materials. Percentage depth doses (PDDs) were measured with thermoluminescent dosimeters (TLDs), metal-oxide semiconductor field-effect transistors (MOSFETs), plane parallel and cylindrical ionization chambers, and beam profiles with films. The MC code used for the simulations was the PENELOPE code. Three different field sizes (10 x 10, 5 x 5, and 2 x 2 cm2) were studied in two phantom configurations and a bone equivalent material. These two phantom configurations contained heterogeneities of 5 and 2 cm of bone, respectively. We analyzed the performance of four correction-based algorithms and one based on convolution superposition. The correction-based algorithms were the Batho, the Modified Batho, the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system (TPS), and the Helax-TMS Pencil Beam from the Helax-TMS (Nucletron) TPS. The convolution-superposition algorithm was the Collapsed Cone implemented in the Helax-TMS. All the correction-based calculation algorithms underestimated the dose inside the bone-equivalent material for 18 MV compared to MC simulations. The maximum underestimation, in terms of root-mean-square (RMS), was about 15% for the Helax-TMS Pencil Beam (Helax-TMS PB) for a 2 x 2 cm2 field inside the bone-equivalent material. In contrast, the Collapsed Cone algorithm yielded values around 3%. A more complex behavior was found for 6 MV where the Collapsed Cone performed less well, overestimating the dose inside the heterogeneity in 3%-5%. The rebuildup in the interface bone-water and the penumbra shrinking in high-density media were not predicted by any of the calculation algorithms except the Collapsed Cone, and only the MC simulations matched the experimental values

  4. 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.

  5. Estimation of the effects of normal tissue sparing using equivalent uniform dose-based optimization

    PubMed Central

    Senthilkumar, K.; Maria Das, K. J.; Balasubramanian, K.; Deka, A. C.; Patil, B. R.

    2016-01-01

    In this study, we intend to estimate the effects of normal tissue sparing between intensity modulated radiotherapy (IMRT) treatment plans generated with and without a dose volume (DV)-based physical cost function using equivalent uniform dose (EUD). Twenty prostate cancer patients were retrospectively selected for this study. For each patient, two IMRT plans were generated (i) EUD-based optimization with a DV-based physical cost function to control inhomogeneity (EUDWith DV) and (ii) EUD-based optimization without a DV-based physical cost function to allow inhomogeneity (EUDWithout DV). The generated plans were prescribed a dose of 72 Gy in 36 fractions to planning target volume (PTV). Mean dose, D30%, and D5% were evaluated for all organ at risk (OAR). Normal tissue complication probability was also calculated for all OARs using BioSuite software. The average volume of PTV for all patients was 103.02 ± 27 cm3. The PTV mean dose for EUDWith DV plans was 73.67 ± 1.7 Gy, whereas for EUDWithout DV plans was 80.42 ± 2.7 Gy. It was found that PTV volume receiving dose more than 115% of prescription dose was negligible in EUDWith DV plans, whereas it was 28% in EUDWithout DV plans. In almost all dosimetric parameters evaluated, dose to OARs in EUDWith DV plans was higher than in EUDWithout DV plans. Allowing inhomogeneous dose (EUDWithout DV) inside the target would achieve better normal tissue sparing compared to homogenous dose distribution (EUDWith DV). Hence, this inhomogeneous dose could be intentionally dumped on the high-risk volume to achieve high local control. Therefore, it was concluded that EUD optimized plans offer added advantage of less OAR dose as well as selectively boosting dose to gross tumor volume. PMID:27217624

  6. Universal Survival Curve and Single Fraction Equivalent Dose: Useful Tools in Understanding Potency of Ablative Radiotherapy

    SciTech Connect

    Park, Clint; Papiez, Lech; Zhang Shichuan; Story, Michael; Timmerman, Robert D.

    2008-03-01

    Purpose: Overprediction of the potency and toxicity of high-dose ablative radiotherapy such as stereotactic body radiotherapy (SBRT) by the linear quadratic (LQ) model led to many clinicians' hesitating to adopt this efficacious and well-tolerated therapeutic option. The aim of this study was to offer an alternative method of analyzing the effect of SBRT by constructing a universal survival curve (USC) that provides superior approximation of the experimentally measured survival curves in the ablative, high-dose range without losing the strengths of the LQ model around the shoulder. Methods and Materials: The USC was constructed by hybridizing two classic radiobiologic models: the LQ model and the multitarget model. We have assumed that the LQ model gives a good description for conventionally fractionated radiotherapy (CFRT) for the dose to the shoulder. For ablative doses beyond the shoulder, the survival curve is better described as a straight line as predicted by the multitarget model. The USC smoothly interpolates from a parabola predicted by the LQ model to the terminal asymptote of the multitarget model in the high-dose region. From the USC, we derived two equivalence functions, the biologically effective dose and the single fraction equivalent dose for both CFRT and SBRT. Results: The validity of the USC was tested by using previously published parameters of the LQ and multitarget models for non-small-cell lung cancer cell lines. A comparison of the goodness-of-fit of the LQ and USC models was made to a high-dose survival curve of the H460 non-small-cell lung cancer cell line. Conclusion: The USC can be used to compare the dose fractionation schemes of both CFRT and SBRT. The USC provides an empirically and a clinically well-justified rationale for SBRT while preserving the strengths of the LQ model for CFRT.

  7. Ambient neutron dose equivalent outside concrete vault rooms for 15 and 18 MV radiotherapy accelerators.

    PubMed

    Martínez-Ovalle, S A; Barquero, R; Gómez-Ros, J M; Lallena, A M

    2012-03-01

    In this work, the ambient dose equivalent, H*(10), due to neutrons outside three bunkers that house a 15- and a 18-MV Varian Clinac 2100C/D and a 15-MV Elekta Inor clinical linacs, has been calculated. The Monte Carlo code MCNPX (v. 2.5) has been used to simulate the neutron production and transport. The complete geometries including linacs and full installations have been built up according to the specifications of the manufacturers and the planes provided by the corresponding medical physical services of the hospitals where the three linacs operate. Two of these installations, those lodging the Varian linacs, have an entrance door to the bunker while the other one does not, although it has a maze with two bends. Various treatment orientations were simulated in order to establish plausible annual equivalent doses. Specifically anterior-posterior, posterior-anterior, left lateral, right lateral orientations and an additional one with the gantry rotated 30° have been studied. Significant dose rates have been found only behind the walls and the door of the bunker, near the entrance and the console, with a maximum of 12 µSv h(-1). Dose rates per year have been calculated assuming a conservative workload for the three facilities. The higher dose rates in the corresponding control areas were 799 µSv y(-1), in the case of the facility which operates the 15-MV Clinac, 159 µSv y(-1), for that with the 15-MV Elekta, and 21 µSv y(-1) for the facility housing the 18-MV Varian. A comparison with measurements performed in similar installations has been carried out and a reasonable agreement has been found. The results obtained indicate that the neutron contamination does not increase the doses above the legal limits and does not produce a significant enhancement of the dose equivalent calculated. When doses are below the detection limits provided by the measuring devices available today, MCNPX simulation provides an useful method to evaluate neutron dose equivalents based

  8. Alternatives to dose, quality factor and dose equivalent for low level irradiation

    SciTech Connect

    Sondhaus, C.A.; Bond, V.P.; Feinendegen, L.E.

    1988-01-01

    Randomly occurring energy deposition events produced by low levels of ionizing radiation interacting with tissue deliver variable amounts of energy to the sensitive target volumes within a small fraction of the cell population. A model is described in which an experimentally derived function relating event size to cell response probability operates mathematically on the microdosimetric event size distribution characterizing a given irradiation and thus determines the total fractional number of responding cells; this fraction measures the effectiveness of the given radiation. Normalizing to equal numbers of events produced by different radiations and applying this cell response or hit size effectiveness function (HSEF) should define radiation quality, or relative effectiveness, on a more nearly absolute basis than do the absorbed dose and dose evaluation, which are confounded when applied to low level irradiations. Examples using both calculation and experimental data are presented. 15 refs., 18 figs.

  9. Dose equivalents of antidepressants: Evidence-based recommendations from randomized controlled trials.

    PubMed

    Hayasaka, Yu; Purgato, Marianna; Magni, Laura R; Ogawa, Yusuke; Takeshima, Nozomi; Cipriani, Andrea; Barbui, Corrado; Leucht, Stefan; Furukawa, Toshi A

    2015-07-15

    Dose equivalence of antidepressants is critically important for clinical practice and for research. There are several methods to define and calculate dose equivalence but for antidepressants, only daily defined dose and consensus methods have been applied to date. The purpose of the present study is to examine dose equivalence of antidepressants by a less arbitrary and more systematic method. We used data from all randomized, double-blind, flexible-dose trials comparing fluoxetine or paroxetine as standard drugs with any other active antidepressants as monotherapy in the acute phase treatment of unipolar depression. We calculated the ratio of the mean doses for each study and weighted it by the total sample size to find the weighted mean ratio for each drug, which was then used to define the drug׳s dosage equivalent to fluoxetine 40mg/d. We included 83 studies (14 131 participants). In the primary analysis, fluoxetine 40mg/day was equivalent to paroxetine dosage of 34.0mg/day, agomelatine 53.2mg/day, amitriptyline, 122.3mg/day, bupropion 348.5mg/day, clomipramine 116.1mg/day, desipramine 196.3mg/day, dothiepin 154.8mg/day, doxepin 140.1mg/day, escitalopram 18.0mg/day, fluvoxamine 143.3mg/day, imipramine 137.2mg/day, lofepramine 250.2mg/day, maprotiline 118.0mg/day, mianserin, 101.1mg/day, mirtazapine 50.9mg/day, moclobemide 575.2mg/day, nefazodone 535.2mg/day, nortriptyline 100.9mg/day, reboxetine 11.5mg/day, sertraline 98.5mg/day, trazodone 401.4mg/day, and venlafaxine 149.4mg/day. Sensitivity analyses corroborated the results except for doxepin. The number of studies for some drugs was small. The current method assumes dose response relationship of antidepressants. Our findings can be useful for clinicians when they switch antidepressants and for researchers when they compare various antidepressants in their research. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  10. SU-E-T-185: Clinically-Relevant Investigation of Flattening Filter Free Skin Dose

    SciTech Connect

    Guy, C; Karki, K; Sharma, M; Kim, S

    2015-06-15

    Purpose: Flattening-filter-free (FFF) beams are increasingly used for small-field treatments due to inherent advantages like higher MU efficiency and reduced treatment time and scatter dose. Removal of the flattening-filter increases the electron contamination and low-energy x-rays. As such, surface-dose characteristics are different from traditional flattened (FF) beams. The goal of this work is to investigate surface dose of 6/10 MV FFF and FF beams under conditions representative of emerging complex techniques like small-field stereotactic treatments which use small fields formed with multi-leaf-collimators (MLCs) at closer SSDs. Methods: A parallel-plate PTW Markus-chamber (N23343) placed in custom air- and water-equivalent phantoms was used to measure surface-dose at 2/3/4/6/8/10/20/30 cm{sup 2} field sizes, at 80/90/100 cm source-to-surface distances, and at fields defined by jaws and MLCs. The effect of dose rate (600 and 1400/2400 MU/min) was also investigated at 100 cm SSD. Measurements were performed on TrueBeam linac (Varian Medical Systems, Palo Alto, CA) for 6X/6XFFF/10X/10XFFF beam energies. Results: No dose-rate dependence was seen for FFF skin-dose. Air-phantom measurements were, on average, 5±3% larger than for water-phantom measurements. With SSD increase from 80 to 100 cm, skin-dose decreased by an average of 3.9±2.5%. FFF beams were found to be more sensitive to SSD changes in comparison to FF beams. The difference in skin dose between MLC- and jaw-fields was less variable with field size for FFF compared to FF beams. 10 MV beams showed greater difference in FFF-to-FF ratio, 50% (jaws) and 22% (MLC), between the largest and smallest field sizes compared to 6 MV beams, 30% (jaws) and 9% (MLC). Conclusion: Under clinically-relevant conditions, surface dose for FFF beams was higher at small field size (<10 cm), lower at largest field size (30 cm), more sensitive to SSD changes, and had less variation with field size compared to dose for FF beams.

  11. Nuclear medicine dose equivalent a method for determination of radiation risk

    SciTech Connect

    Huda, W.

    1986-12-01

    Conventional nuclear medicine dosimetry involves specifying individual organ doses. The difficulties that can arise with this approach to radiation dosimetry are discussed. An alternative scheme is described that is based on the ICRP effective dose equivalent, H/sub E/, and which is a direct estimate of the average radiation risk to the patient. The mean value of H/sub E/ for seven common /sup 99m/Tc nuclear medicine procedures is 0.46 rem and the average radiation risk from this level of exposure is estimated to be comparable to the risk from smoking approx. 28 packs of cigarettes or driving approx. 1300 miles.

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

    PubMed

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

    2011-11-21

    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.

  13. 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.

  14. A comparison of analytic models for estimating dose equivalent rates in shielding with beam spill measurements

    SciTech Connect

    Frankle, S.C.; Fitzgerald, D.H.; Hutson, R.L.; Macek, R.J.; Wilkinson, C.A.

    1992-12-31

    A comparison of 800-MeV proton beam spill measurements at the Los Alamos Meson Physics Facility (LAMPF) with analytical model calculations of neutron dose equivalent rates (DER) show agreement within factors of 2-3 for simple shielding geometries. The DER estimates were based on a modified Moyer model for transverse angles and a Monte Carlo based forward angle model described in the proceeding paper.

  15. Considerations on Estimating Upper Bounds of Neutron Doses Equivalents to Military Participants at Atmospheric Nuclear Tests

    DTIC Science & Technology

    2007-04-01

    Tissue kerma for monoenergetic neutrons of energy up to 14 MeV and contributions from different interactions that produce charged ionizing particles...fluence for each energy group obtained from calculations for monoenergetic neutrons similar to calculations in Figure 2-I, and the energy dependence of the...Considerations on Estimating Upper Bounds of Neutron Dose Equivalents to Military Partici pants at Atmospheric Nuclear Tests Approved for public release

  16. Simultaneous optical coherence and multiphoton microscopy of skin-equivalent tissue models

    NASA Astrophysics Data System (ADS)

    Barton, Jennifer K.; Tang, Shuo; Lim, Ryan; Tromberg, Bruce J.

    2007-07-01

    Three-layer skin-equivalent models (rafts) were created consisting of a collagen/fibroblast layer and an air-exposed keratinocyte layer. Rafts were imaged with a tri-modality microscope including optical coherence (OC), two-photon excited fluorescence (TPEF), and second harmonic generation (SHG) channels. Some rafts were stained with Hoechst 33343 or rhodamine 123, and some were exposed to dimethyl sulfoxide (DMSO). OC microscopy revealed signal in cell cytoplasm and nuclear membranes, and a characteristic texture in the collagen/fibroblast layer. TPEF showed signal in cell cytoplasm and from collagen, and stained specimens revealed cell nuclei or mitochondria. There was little SHG in the keratinocyte layer, but strong signal from collagen bundles. Endogenous signals were severely attenuated in DMSO treated rafts; stained samples revealed shrunken and distorted cell structure. OC, TPEF, and SHG can provide complementary and non-destructive information about raft structure and effect of chemical agents.

  17. Measurement of neutron dose equivalent outside and inside of the treatment vault of GRID therapy

    SciTech Connect

    Wang, Xudong; Charlton, Michael A.; Esquivel, Carlos; Eng, Tony Y.; Li, Ying; Papanikolaou, Nikos

    2013-09-15

    Purpose: To evaluate the neutron and photon dose equivalent rates at the treatment vault entrance (H{sub n,D} and H{sub G}), and to study the secondary radiation to the patient in GRID therapy. The radiation activation on the grid was studied.Methods: A Varian Clinac 23EX accelerator was working at 18 MV mode with a grid manufactured by .decimal, Inc. The H{sub n,D} and H{sub G} 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{sup ®} phantom.Results: Within the measurement uncertainty, there is no significant difference between the H{sub n,D} and H{sub G} 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.Conclusions: This work indicates that there is no significant change of the H{sub n,D} and H{sub G} 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

  18. Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams.

    PubMed

    Zheng, Yuanshui; Liu, Yaxi; Zeidan, Omar; Schreuder, Andries Niek; Keole, Sameer

    2012-06-01

    Neutron exposure is of concern in proton therapy, and varies with beam delivery technique, nozzle design, and treatment conditions. Uniform scanning is an emerging treatment technique in proton therapy, but neutron exposure for this technique has not been fully studied. The purpose of this study is to investigate the neutron dose equivalent per therapeutic dose, H/D, under various treatment conditions for uniform scanning beams employed at our proton therapy center. Using a wide energy neutron dose equivalent detector (SWENDI-II, ThermoScientific, MA), the authors measured H/D at 50 cm lateral to the isocenter as a function of proton range, modulation width, beam scanning area, collimated field size, and snout position. They also studied the influence of other factors on neutron dose equivalent, such as aperture material, the presence of a compensator, and measurement locations. They measured H/D for various treatment sites using patient-specific treatment parameters. Finally, they compared H/D values for various beam delivery techniques at various facilities under similar conditions. H/D increased rapidly with proton range and modulation width, varying from about 0.2 mSv/Gy for a 5 cm range and 2 cm modulation width beam to 2.7 mSv/Gy for a 30 cm range and 30 cm modulation width beam when 18 × 18 cm(2) uniform scanning beams were used. H/D increased linearly with the beam scanning area, and decreased slowly with aperture size and snout retraction. The presence of a compensator reduced the H/D slightly compared with that without a compensator present. Aperture material and compensator material also have an influence on neutron dose equivalent, but the influence is relatively small. H/D varied from about 0.5 mSv/Gy for a brain tumor treatment to about 3.5 mSv/Gy for a pelvic case. This study presents H/D as a function of various treatment parameters for uniform scanning proton beams. For similar treatment conditions, the H/D value per uncollimated beam size for

  19. Measurements of neutron dose equivalent for a proton therapy center using uniform scanning proton beams

    SciTech Connect

    Zheng Yuanshui; Liu Yaxi; Zeidan, Omar; Schreuder, Andries Niek; Keole, Sameer

    2012-06-15

    Purpose: Neutron exposure is of concern in proton therapy, and varies with beam delivery technique, nozzle design, and treatment conditions. Uniform scanning is an emerging treatment technique in proton therapy, but neutron exposure for this technique has not been fully studied. The purpose of this study is to investigate the neutron dose equivalent per therapeutic dose, H/D, under various treatment conditions for uniform scanning beams employed at our proton therapy center. Methods: Using a wide energy neutron dose equivalent detector (SWENDI-II, ThermoScientific, MA), the authors measured H/D at 50 cm lateral to the isocenter as a function of proton range, modulation width, beam scanning area, collimated field size, and snout position. They also studied the influence of other factors on neutron dose equivalent, such as aperture material, the presence of a compensator, and measurement locations. They measured H/D for various treatment sites using patient-specific treatment parameters. Finally, they compared H/D values for various beam delivery techniques at various facilities under similar conditions. Results: H/D increased rapidly with proton range and modulation width, varying from about 0.2 mSv/Gy for a 5 cm range and 2 cm modulation width beam to 2.7 mSv/Gy for a 30 cm range and 30 cm modulation width beam when 18 Multiplication-Sign 18 cm{sup 2} uniform scanning beams were used. H/D increased linearly with the beam scanning area, and decreased slowly with aperture size and snout retraction. The presence of a compensator reduced the H/D slightly compared with that without a compensator present. Aperture material and compensator material also have an influence on neutron dose equivalent, but the influence is relatively small. H/D varied from about 0.5 mSv/Gy for a brain tumor treatment to about 3.5 mSv/Gy for a pelvic case. Conclusions: This study presents H/D as a function of various treatment parameters for uniform scanning proton beams. For similar treatment

  20. VARSKIN MOD 2 and SADDE MOD2: Computer codes for assessing skin dose from skin contamination

    SciTech Connect

    Durham, J.S. )

    1992-12-01

    The computer code VARSKIN has been modified to calculate dose to skin from three-dimensional sources, sources separated from the skin by layers of protective clothing, and gamma dose from certain radionuclides correction for backscatter has also been incorporated for certain geometries. This document describes the new code, VARSKIN Mod 2, including installation and operation instructions, provides detailed descriptions of the models used, and suggests methods for avoiding misuse of the code. The input data file for VARSKIN Mod 2 has been modified to reflect current physical data, to include the contribution to dose from internal conversion and Auger electrons, and to reflect a correction for low-energy electrons. In addition, the computer code SADDE: Scaled Absorbed Dose Distribution Evaluator has been modified to allow the generation of scaled absorbed dose distributions for mixtures of radionuclides and intereat conversion and Auger electrons. This new code, SADDE Mod 2, is also described in this document. Instructions for installation and operation of the code and detailed descriptions of the models used in the code are provided.

  1. Evaluation of external dose equivalent with thermoluminescent dosimeters from residents living in radiation-contaminated buildings.

    PubMed

    Lee, J S; Dong, S L; Chang, W P; Chan, C C

    1997-09-01

    As of October 1996 there are more than 90 radiation-contaminated steel supported rebar buildings (containing more than 1000 apartments) dispersed in the northern part of Taiwan. These apartments were contaminated with cobalt-60 at a total activity ranging from 1-140 microSv/yr. In this paper, a method is developed for evaluating external dose equivalent and dose equivalent rates encountered by the residents wearing specially designed thermoluminescent dosimeter (TLD)-embedded chains, belts and badges. Comparisons are also made between the TLD readings and the exposure readings from indoor layout personal dosimetry surveys and room occupancy adjustments to the buildings. The accuracy and sensitivity of the TLDs compared with the ionization chamber readings are judged to be considerable improvements over those of previous studies. From the present study, it is concluded that the reliability of the daily activity records provided by the residents during the entire TLD-wearing period is the most critical but challenging feature of the external dose equivalent measurement.

  2. Personal dose equivalent angular response factors for photons with energies up to 1 GeV.

    PubMed

    Veinot, K G

    2013-04-01

    When performing personal dosemeter calibrations, the dosemeters are typically irradiated while mounted on slab-type phantoms and oriented facing the source. Performance testing standards or intercomparison studies may also specify various rotational angles to test the response of the dosemeter and associated algorithm as this rotation introduces changes in the quantity of delivered dose. Correction factors for rotational effects are available, but many have not been updated in recent years and were typically calculated using the kerma approximation. The personal dose equivalent, Hp(d), is the quantity recommended by the International Commission on Radiation Units and Measurements 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, but typically the location of interest is the trunk where personal dosemeters are worn and in this instance a suitable approximation is a 30 cm × 30 cm × 15 cm slab-type phantom. In this work personal dose equivalent conversion coefficients for photons with energies up to 1 GeV have been calculated for depths of 0.007, 0.3 and 1.0 cm in the slab phantom for rotational angles ranging from 15° to 75°. Angular response factors have been determined by comparing the conversion coefficients for each angle and energy to those reported in an earlier work for a non-rotational (e.g. perpendicular to the phantom face) geometry. The angular response factors were determined for discrete angles, but fits of the factors are provided.

  3. How biophysical in vivo testing techniques can be used to characterize full thickness skin equivalents.

    PubMed

    Houcine, A; Delalleau, A; Heraud, S; Guiraud, B; Payre, B; Duplan, H; Delisle, M-B; Damour, O; Bessou-Touya, S

    2016-08-01

    The reliability of the biophysical properties of skin equivalents (SEs) remains a challenge for medical applications and for product efficacy tests following the European Directive 2003/15/EC2 on the prohibition of animal experiments for cosmetic products. We propose to adapt the biophysical in vivo testing techniques to compare full thickness model growth vs. time. The interest in using such techniques lies in possible comparisons between in vivo and in vitro skin as well as monitoring samples over the culture time. High frequency ultrasound technique, optical coherence tomography (OCT), and laser scanning microscopy were used to analyze SEs morphology at days D42 and D60 whereas their microstructure was assessed through transmission electron microscopy and classical histology. A correlation between these observations and mechanical measurements has been proposed so as to underline the consequence of both the development of the dermis elastic fibers and the epidermis differentiation. Ultrasounds measurements show a highly homogeneous dermis whereas the OCT technique clearly distinguishes the stratum corneum and the living epidermis. The increase in the thicknesses of these layers as well as the growth in elastin and collagen fibers results in strong modifications of the samples mechanical properties. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Increased presence of monounsaturated fatty acids in the stratum corneum of human skin equivalents.

    PubMed

    Thakoersing, Varsha S; van Smeden, Jeroen; Mulder, Aat A; Vreeken, Rob J; El Ghalbzouri, Abdoelwaheb; Bouwstra, Joke A

    2013-01-01

    Previous results showed that our in-house human skin equivalents (HSEs) differ in their stratum corneum (SC) lipid organization compared with human SC. To elucidate the cause of the altered SC lipid organization in the HSEs, a recently developed liquid chromatography/mass spectrometry method was used to study the free fatty acid (FFA) and ceramide composition in detail. In addition, the SC lipid composition of the HSEs and human skin was examined quantitatively with high-performance thin-layer chromatography. Our results reveal that all our HSEs have an increased presence of monounsaturated FFAs compared with human SC. Moreover, the HSEs display the presence of ceramide species with a monounsaturated acyl chain, which are not detected in human SC. All HSEs also exhibit an altered expression of stearoyl-CoA desaturase, the enzyme that converts saturated FFAs to monounsaturated FFAs. Furthermore, the HSEs show the presence of 12 ceramide subclasses, similar to native human SC. However, the HSEs have increased levels of ceramides EOS and EOH and ceramide species with short total carbon chains and a reduced FFA level compared with human SC. The presence of unsaturated lipid chains in HSE offers new opportunities to mimic the lipid properties of human SC more closely.

  5. Measured Head CT/CTA Skin Dose and Intensive Care Unit Patient Cumulative Exposure.

    PubMed

    Nawfel, R D; Young, G S

    2017-03-01

    Estimates of cumulative CT/CTA radiation dose based on volumetric CT dose index have raised concern that neurological intensive care unit patient exposures may reach thresholds for deterministic skin injury. Because the accuracy of volumetric CT dose index for this purpose in unknown, we set out to directly measure head CT and CTA peak skin dose, assess the relationship of volumetric CT dose index to measured peak skin dose, and determine whether multiple CT/CTA exposures in typical patients in the neurological intensive care unit produce cumulative doses approaching or exceeding single-dose deterministic thresholds for skin injury. In a prospective study from 2011-2013, nanoDot optical stimulated luminescence dosimeters were used to measure head CT/CTA peak skin dose in 52 patients (28 female, 24 male; mean age, 63 years) divided equally between 2 CT scanners. Volumetric CT dose index and dose-length product were recorded for each examination. Peak skin dose was also measured on an acrylic skull phantom in each scanner. A 2-tailed, unpaired t test was used to compare mean patient skin doses between the 2 scanners. The measured peak skin doses were then used to calculate cumulative peak skin dose in 4 typical patients in intensive care units who received multiple CT/CTA scans. Head CT/CTA peak skin dose agreed between scanners in patients and phantoms: (scanner 1 CT/CTA: patients, 39.2 ± 3.7 mGy and 98.9 ± 5.3 mGy, respectively, versus phantom, 40.0 mGy and 105.4 mGy, respectively; scanner 2 CT/CTA: patients, 42.9 ± 9.4 mGy and 98.8 ± 7.4 mGy, respectively, versus phantom, 37.6 mGy and 95.2 mGy, respectively). Volumetric CT dose index overestimated peak skin dose by a factor of 1.4-1.9 depending on examination and CT scanner. Cumulative doses in 4 patients in the intensive care unit estimated from measured CT/CTA peak skin dose ranged from 1.9-4.5 Gy. Directly measured radiation skin doses from head CT/CTA patient examinations are substantially lower than

  6. How accurately can the peak skin dose in fluoroscopy be determined using indirect dose metrics?

    SciTech Connect

    Jones, A. Kyle; Ensor, Joe E.; Pasciak, Alexander S.

    2014-07-15

    Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that result in skin reactions can be reached during these procedures. There is no consensus as to whether or not indirect skin dosimetry is sufficiently accurate for fluoroscopically-guided interventions. However, measuring PSD with film is difficult and the decision to do so must be madea priori. The purpose of this study was to assess the accuracy of different types of indirect dose estimates and to determine if PSD can be calculated within ±50% using indirect dose metrics for embolization procedures. Methods: PSD were measured directly using radiochromic film for 41 consecutive embolization procedures at two sites. Indirect dose metrics from the procedures were collected, including reference air kerma. Four different estimates of PSD were calculated from the indirect dose metrics and compared along with reference air kerma to the measured PSD for each case. The four indirect estimates included a standard calculation method, the use of detailed information from the radiation dose structured report, and two simplified calculation methods based on the standard method. Indirect dosimetry results were compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the different indirect estimates were examined. Results: When using the standard calculation method, calculated PSD were within ±35% for all 41 procedures studied. Calculated PSD were within ±50% for a simplified method using a single source-to-patient distance for all calculations. Reference air kerma was within ±50% for all but one procedure. Cases for which reference air kerma or calculated PSD exhibited large (±35%) differences from the measured PSD were analyzed, and two main causative factors were identified: unusually small or large source-to-patient distances and large contributions to reference air kerma from cone

  7. Method for preparing dosimeter for measuring skin dose

    DOEpatents

    Jones, Donald E.; Parker, DeRay; Boren, Paul R.

    1982-01-01

    A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with neutron-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

  8. Dosimeter for measuring skin dose and more deeply penetrating radiation

    DOEpatents

    Jones, Donald E.; Parker, DeRay; Boren, Paul R.

    1981-01-01

    A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with netruon-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

  9. Personal dose equivalent conversion coefficients for photons to 1 GeV.

    PubMed

    Veinot, K G; Hertel, N E

    2011-04-01

    The personal dose equivalent, H(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 × 30 × 15 cm(3) slab-type phantom. For this condition, the personal dose equivalent is denoted as H(p,slab)(d) and the depths, 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 megaelectronvolts, however, data to higher energies are limited. In this work, conversion coefficients up to 1 GeV have been calculated for H(p,slab)(10) and H(p,slab)(3) both by using the kerma approximation and tracking secondary charged particles. For H(p)(0.07), the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H(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 with the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on Radiological

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

    SciTech Connect

    Ma Lijun; Sahgal, Arjun; Descovich, Martina; Cho, Y.-B.; Chuang, Cynthia; Huang, Kim; Laperriere, Normand J.; Shrieve, Dennis C.; Larson, David A.

    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 (1 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.

  11. Relationship between fluoroscopic time, dose-area product, body weight, and maximum radiation skin dose in cardiac interventional procedures.

    PubMed

    Chida, Koichi; Saito, Haruo; Otani, Hiroki; Kohzuki, Masahiro; Takahashi, Shoki; Yamada, Shogo; Shirato, Kunio; Zuguchi, Masayuki

    2006-03-01

    Real-time maximum dose monitoring of the skin is unavailable on many of the X-ray machines that are used for cardiac intervention procedures. Therefore, some reports have recommended that physicians record the fluoroscopic time for patients undergoing fluoroscopically guided intervention procedures. However, the relationship between the fluoroscopic time and the maximum radiation skin dose is not clear. This article describes the correlation between the maximum radiation skin dose and fluoroscopic time for patients undergoing cardiac intervention procedures. In addition, we examined whether the correlations between maximum radiation skin dose and body weight, fluoroscopic time, and dose-area product (DAP) were useful for estimating the maximum skin dose during cardiac intervention procedures. Two hundred consecutive cardiac intervention procedures were studied: 172 percutaneous coronary interventions and 28 cardiac radiofrequency catheter ablation (RFCA) procedures. The patient skin dose and DAP were measured using Caregraph with skin-dose-mapping software. For the RFCA procedures, we found a good correlation between the maximum radiation skin dose and fluoroscopic time (r = 0.801, p < 0.0001), whereas we found a poor correlation between the maximum radiation skin dose and fluoroscopic time for the percutaneous coronary intervention procedures (r = 0.628, p < 0.0001). There was a strong correlation between the maximum radiation skin dose and DAP in RFCA procedures (r = 0.942, p < 0.0001). There was also a significant correlation between the maximum radiation skin dose and DAP (r = 0.724, p < 0.0001) and weight-fluoroscopic time product (WFP) (r = 0.709, p < 0.0001) in percutaneous coronary intervention procedures. The correlation between the maximum radiation skin dose with DAP is more striking than that with fluoroscopic time in both RFCA and percutaneous coronary intervention procedures. We recommend that physicians record the DAP when it can be monitored and

  12. Determination of the optical properties of melanin-pigmented human skin equivalents using terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Lipscomb, Dawn; Echchgadda, Ibtissam; Peralta, Xomalin G.; Wilmink, Gerald J.

    2013-02-01

    Terahertz time-domain spectroscopy (THz-TDS) methods have been utilized in previous studies in order to characterize the optical properties of skin and its primary constituents (i.e., water, collagen, and keratin). However, similar experiments have not yet been performed to investigate whether melanocytes and the melanin pigment that they synthesize contribute to skin's optical properties. In this study, we used THz-TDS methods operating in transmission geometry to measure the optical properties of in vitro human skin equivalents with or without normal human melanocytes. Skin equivalents were cultured for three weeks to promote gradual melanogenesis, and THz time domain data were collected at various time intervals. Frequency-domain analysis techniques were performed to determine the index of refraction (n) and absorption coefficient (μa) for each skin sample over the frequency range of 0.1-2.0 THz. We found that for all samples as frequency increased, n decreased exponentially and the μa increased linearly. Additionally, we observed that skin samples with higher levels of melanin exhibited greater n and μa values than the non-pigmented samples. Our results indicate that melanocytes and the degree of melanin pigmentation contribute in an appreciable manner to the skin's optical properties. Future studies will be performed to examine whether these contributions are observed in human skin in vivo.

  13. Dose-response effect of human equivalent radiation in the murine mandible: A radiomorphometric assessment

    PubMed Central

    Monson, Laura A.; Jing, X. Lin; Donneys, Alexis; Farberg, Aaron S.; Buchman, Steven R.

    2016-01-01

    Background Despite widespread use of adjuvant irradiation for head and neck cancer, the extent of damage to the underlying bone is not fully understood, but is associated with pathologic fractures, nonunion, and osteoradionecrosis. The authors’ laboratory previously demonstrated that radiation significantly impedes new bone formation in the murine mandible. We hypothesize that the detrimental effects of human equivalent radiation on the murine mandible results in a dose-dependent degradation in traditional micro-CT metrics. Methods Fifteen male Sprague-Dawley rats were randomized into three radiation dosage groups: low (5.91 Gy), middle (7 Gy), and high (8.89 Gy), delivered in five daily fractions. These dosages approximated 75, 100 and 150 percent, respectively, of the biologically equivalent dose that the human mandible receives during radiation treatment. Hemimandibles were harvested 56 days after radiation and scanned using microCT. Bone mineral density, tissue mineral density, and bone volume fraction were measured along with microdensitometry measurements. Results Animals demonstrated dose dependent side effects of mucositis, alopecia, weight loss and mandibular atrophy with increasing radiation. Traditional microCT parameters were not sensitive enough to demonstrate statistically significant differences between the radiated groups; however microdensitometry analysis showed clear differences between radiated groups and statistically significant changes between radiated and non-radiated groups. Conclusions The authors report dose-dependent and clinically significant side effects of fractionated human equivalent radiation to the murine mandible. The authors further report the limited capacity of traditional micro-CT metrics to adequately capture key changes in bone composition and present microdensitometric histogram analysis in order to demonstrate significant radiation induced changes in mineralization patterns. PMID:24036733

  14. Establishing an effective dose equivalent monitoring program for a commercial nuclear power station

    NASA Astrophysics Data System (ADS)

    Thompson, Barbara Jane

    The purpose of this thesis is to determine whether monitoring personnel with multiple dosimeter badges to determine effective dose equivalent (EDE) is both acceptable to the Nuclear Regulatory Commission (NRC) and practical for the nuclear power industry. Until now, most nuclear power plants have used a single dosimeter or occasionally multiple dosimeters to monitor the "deep dose equivalent (DDE)" as defined by the International Commission on Radiological Units (ICRU). The measurement of EDE, to replace DDE, is now deemed by international and regulatory agencies to better approximate a worker's dose related to long-term risks of occupational radiation exposure. The definition of DDE, and the formulation of EDE for use as a new indicator of occupational exposure, are presented in this thesis. Radiation exposure measurements using multiple dosimeters on each worker for certain tasks were collected for this thesis on workers at a Dominion/Virginia Company nuclear power plant. These multiple dosimeter measurements have been examined to determine how such a new personnel monitoring system compares to the former one at the Dominion plant, in which only one dosimeter reading was used predominately to calculated deep dose equivalent. This is based on the assumption that most workers were exposed to uniform radiation fields and that the single dosimeter reading was representative of the highest average exposure for the worker's task. These multiple dosimetry measurements show that it is both feasible and advantageous to provide such dosimetry in situations where exposures may be non-uniform and significant enough to approach yearly exposure limits in a single day, such as in the tasks required during refueling outages.

  15. Skin dose saving of the staff in 90Y/177Lu peptide receptor radionuclide therapy with the automatic dose dispenser.

    PubMed

    Fioroni, Federica; Grassi, Elisa; Giorgia, Cavatorta; Sara, Rubagotti; Piccagli, Vando; Filice, Angelina; Mostacci, Domiziano; Versari, Annibale; Iori, Mauro

    2016-10-01

    When handling Y-labelled and Lu-labelled radiopharmaceuticals, skin exposure is mainly due to β-particles. This study aimed to investigate the equivalent dose saving of the staff when changing from an essentially manual radiolabelling procedure to an automatic dose dispenser (ADD). The chemist and physician were asked to wear thermoluminescence dosimeters on their fingertips to evaluate the quantity of Hp(0.07) on the skin. Data collected were divided into two groups: before introducing ADD (no ADD) and after introducing ADD. For the chemist, the mean values (95th percentile) of Hp(0.07) for no ADD and ADD are 0.030 (0.099) and 0.019 (0.076) mSv/GBq, respectively, for Y, and 0.022 (0.037) and 0.007 (0.023) mSv/GBq, respectively, for Lu. The reduction for ADD was significant (t-test with P<0.05) for both isotopes. The relative differences before and after ADD collected for every finger were treated using the Wilcoxon test, proving a significantly higher reduction in extremity dose to each fingertip for Lu than for Y (P<0.05). For the medical staff, the mean values of Hp(0.07) (95th percentile) for no ADD and ADD are 0.021 (0.0762) and 0.0143 (0.0565) mSv/GBq, respectively, for Y, and 0.0011 (0.00196) and 0.0009 (0.00263) mSv/GBq, respectively, for Lu. The t-test provided a P-value less than 0.05 for both isotopes, making the difference between ADD and no ADD significant. ADD positively affects the dose saving of the chemist in handling both isotopes. For the medical staff not directly involved with the introduction of the ADD system, the analysis shows a learning curve of the workers over a 5-year period. Specific devices and procedures allow staff skin dose to be limited.

  16. On relating the generalized equivalent uniform dose formalism to the linear-quadratic model.

    PubMed

    Djajaputra, David; Wu, Qiuwen

    2006-12-01

    Two main approaches are commonly used in the literature for computing the equivalent uniform dose (EUD) in radiotherapy. The first approach is based on the cell-survival curve as defined in the linear-quadratic model. The second approach assumes that EUD can be computed as the generalized mean of the dose distribution with an appropriate fitting parameter. We have analyzed the connection between these two formalisms by deriving explicit formulas for the EUD which are applicable to normal distributions. From these formulas we have established an explicit connection between the two formalisms. We found that the EUD parameter has strong dependence on the parameters that characterize the distribution, namely the mean dose and the standard deviation around the mean. By computing the corresponding parameters for clinical dose distributions, which in general do not follow the normal distribution, we have shown that our results are also applicable to actual dose distributions. Our analysis suggests that caution should be used in using generalized EUD approach for reporting and analyzing dose distributions.

  17. Tritons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-12-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to tritons ((3)H(+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Coefficients were calculated using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and calculation of gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 3%. The greatest difference, 43%, occurred at 30 MeV.

  18. Helions at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    PubMed

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2010-12-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent, for isotropic exposure of an adult male and an adult female to helions ((3)He(2+)) in the energy range of 10 MeV to 1 TeV (0.01-1000 GeV). Calculations were performed using Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms modified to allow calculation of effective dose using tissues and tissue weighting factors from either the 1990 or 2007 recommendations of the International Commission on Radiological Protection (ICRP), and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. At 15 of the 19 energies for which coefficients for effective dose were calculated, coefficients based on ICRP 2007 and 1990 recommendations differed by less than 2%. The greatest difference, 62%, occurred at 100 MeV.

  19. 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.

  20. 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.

  1. Focused neutron beam dose deposition profiles in tissue equivalent materials: a pilot study for BNCT

    NASA Astrophysics Data System (ADS)

    Mayer, Rulon R.; Welsh, James; Chen-Mayer, Huaiyu H.

    1997-02-01

    Boron Neutron Capture Therapy (BNCT) has been limited by the inability to direct neutrons toward the therapeutic target and away from sensitive normal tissues. The recently developed Kumakhov lens has focused a broad incident low energy neutron beam in air to a sub-mm spot. This study examines the radiation does distribution of a converging beam passing through tissue equivalent materials. A neutron beam exiting a focusing lens is directed toward a stack of thin radiochromic media sandwiched between plastic sheets. The depth dose and beam profile within the tissue equivalent materials are determined by optical scanning and image processing of the individual radiochromic media sheets, a polymer based dosimetry medium which darkens upon exposure to ionizing radiation. The alpha particle emission from boron is examined by substituting a plastic sheet with a 6Li enriched lithium carbonate sheet positioned at the focal plane. The information will help determine the feasibility of applying the focused neutron beam to BNCT for therapy.

  2. Evaluation of neutron dose equivalent from the Mevion S250 proton accelerator: measurements and calculations

    NASA Astrophysics Data System (ADS)

    Chen, Kuan Ling; Bloch, Charles D.; Hill, Patrick M.; Klein, Eric E.

    2013-12-01

    Neutron production is of concern for proton therapy, especially for passive scattering proton beam delivery methods. The levels of neutron dose equivalent vary significantly with system design and treatment parameters. The purpose of this study was to examine neutron dose equivalent per therapeutic dose (H/D) around the Mevion S250 proton therapy system, a novel design of proton therapy systems. The benchmark comparisons between measurement and simulation were found to be within a factor of 2 for most cases. The H/D values were evaluated as a function of various parameters. The results showed that, at a standard reference condition (10 × 10 cm2 field size, distance 1 m detector-to-isocenter lateral to the primary proton beam direction), the H/D values range from 0.72 to 3.37 mSv Gy-1 for all configurations studied. The H/D values generally (1) decreased as the neutron detectors moved away from the isocenter, (2) decreased with increasing aperture field sizes, (3) increased with increasing angle from the initial beam axis and (4) were independent of treatment nozzle position. The H/D trends were consistent with other existing passive scattering proton accelerators reported in the literature.

  3. Time-dependent estimates of organ dose and dose equivalent rates for human crews in deep space from the 26 October 2003 solar energetic particle event (Halloween event) using the Earth-Moon-Mars Radiation Environment Module

    NASA Astrophysics Data System (ADS)

    PourArsalan, M.; Townsend, L. W.; Schwadron, N. A.; Kozarev, K.; Dayeh, M. A.; Desai, M. I.

    2010-08-01

    The Earth-Moon-Mars Radiation Environment Module is being developed for use by a broad spectrum of researchers to predict energetic particle intensities and radiation exposures at any location in deep space. In this work we demonstrate the capabilities of the module for performing analyses of time-dependent exposures from solar energetic particle events at various locations in space by calculating cumulative dose and dose equivalent, and their time rates of change, for the skin and bone marrow of crew members shielded by as much as 10 g/cm2 of aluminum shielding for the Halloween events of late October 2003.

  4. A new online detector for estimation of peripheral neutron equivalent dose in organ.

    PubMed

    Irazola, L; Lorenzoli, M; Bedogni, R; Pola, A; Terrón, J A; Sanchez-Nieto, B; Expósito, M R; Lagares, J I; Sansaloni, F; Sanchez-Doblado, F

    2014-11-01

    Peripheral dose in radiotherapy treatments represents a potential source of secondary neoplasic processes. As in the last few years, there has been a fast-growing concern on neutron collateral effects, this work focuses on this component. A previous established methodology to estimate peripheral neutron equivalent doses relied on passive (TLD, CR39) neutron detectors exposed in-phantom, in parallel to an active [static random access memory (SRAMnd)] thermal neutron detector exposed ex-phantom. A newly miniaturized, quick, and reliable active thermal neutron detector (TNRD, Thermal Neutron Rate Detector) was validated for both procedures. This first miniaturized active system eliminates the long postprocessing, required for passive detectors, giving thermal neutron fluences in real time. To validate TNRD for the established methodology, intrinsic characteristics, characterization of 4 facilities [to correlate monitor value (MU) with risk], and a cohort of 200 real patients (for second cancer risk estimates) were evaluated and compared with the well-established SRAMnd device. Finally, TNRD was compared to TLD pairs for 3 generic radiotherapy treatments through 16 strategic points inside an anthropomorphic phantom. The performed tests indicate similar linear dependence with dose for both detectors, TNRD and SRAMnd, while a slightly better reproducibility has been obtained for TNRD (1.7% vs 2.2%). Risk estimates when delivering 1000 MU are in good agreement between both detectors (mean deviation of TNRD measurements with respect to the ones of SRAMnd is 0.07 cases per 1000, with differences always smaller than 0.08 cases per 1000). As far as the in-phantom measurements are concerned, a mean deviation smaller than 1.7% was obtained. The results obtained indicate that direct evaluation of equivalent dose estimation in organs, both in phantom and patients, is perfectly feasible with this new detector. This will open the door to an easy implementation of specific

  5. Impact of sweating on equivalent dose of patients treated with 131Iiodine

    PubMed Central

    Haghighatafshar, Mahdi; Banani, Aida; Gheisari, Farshid; Alikhani, Mohammad

    2016-01-01

    Background: Radioiodine therapy is used for the treatment of patients with differentiated thyroid cancer (DTC) who undergo total thyroidectomy. After radioiodine administration, regulations require to quarantine these patients until their retained activity reduces to <33 mCi. Some of the injected radioiodine is excreted by perspiration which helps dose reduction so that performing the activities which stimulate sweating such as exercise may shorten the time of dose reduction. To the best of our knowledge, this is the first study in the literature that has evaluated the impact of specific exercise program on the ambient equivalent dose of 131I gamma rays. Materials and Methods: Patients with DTC without metastasis who had undergone total thyroidectomy and were treated with radioiodine were included in this study. 30 patients were chosen among patients who were able to exercise, did not have renal failure, and did not use diuretics. Patients were divided into two control and intervention groups. Intervention group members walked on treadmills under a specific program, in 3 time intervals. The control group did not have any specific activity. Immediately after each exercise process, both groups took a shower, and their doses were measured by a survey dosimeter. Results: It was revealed that there was a significant difference between mean values before and after each exercise time. The calculated P value which evaluates the overall impact was 0.939 which revealed that there was no significant difference between total ambient equivalent dose reductions of both groups. Conclusion: According to the study, it may conclude that sweating is an effective alternative way for radioiodine excretion, and if sweating is accompanied with well-hydrated status they may have synergism effect to shorten quarantine period. This could be an important consideration in patients which over-hydration is intolerable especially those with cardiac, liver, or renal problems. PMID:27385884

  6. Assessment of penetration of quantum dots through in vitro and in vivo human skin using the human skin equivalent model and the tape stripping method

    SciTech Connect

    Jeong, Sang Hoon; Kim, Jae Hwan; Yi, Sang Min; Lee, Jung Pyo; Kim, Jin Ho; Sohn, Kyung Hee; Park, Kui Lea; Kim, Meyoung-Kon; Son, Sang Wook

    2010-04-09

    Quantum dots (QDs) are rapidly emerging as an important class of nanoparticles (NPs) with potential applications in medicine. However, little is known about penetration of QDs through human skin. This study investigated skin penetration of QDs in both in vivo and in vitro human skin. Using the tape stripping method, this study demonstrates for the first time that QDs can actually penetrate through the stratum corneum (SC) of human skin. Transmission electron microscope (TEM) and energy diverse X-ray (EDX) analysis showed accumulation of QDs in the SC of a human skin equivalent model (HSEM) after dermal exposure to QDs. These findings suggest possible transdermal absorption of QDs after dermal exposure over a relatively long period of time.

  7. Incorporation of functional imaging data in the evaluation of dose distributions using the generalized concept of equivalent uniform dose

    NASA Astrophysics Data System (ADS)

    Miften, Moyed M.; Das, Shiva K.; Su, Min; Marks, Lawrence B.

    2004-05-01

    Advances in the fields of IMRT and functional imaging have greatly increased the prospect of escalating the dose to highly active or hypoxic tumour sub-volumes and steering the dose away from highly functional critical structure regions. However, current clinical treatment planning and evaluation tools assume homogeneous activity/function status in the tumour/critical structures. A method was developed to incorporate tumour/critical structure heterogeneous functionality in the generalized concept of equivalent uniform dose (EUD). The tumour and critical structures functional EUD (FEUD) values were calculated from the dose-function histogram (DFH), which relates dose to the fraction of total function value at that dose. The DFH incorporates flouro-deoxyglucose positron emission tomography (FDG-PET) functional data for tumour, which describes the distribution of metabolically active tumour clonogens, and single photon emission computed tomography (SPECT) perfusion data for critical structures. To demonstrate the utility of the method, the lung dose distributions of two non-small cell lung caner patients, who received 3D conformal external beam radiotherapy treatment with curative intent, were evaluated. Differences between the calculated lungs EUD and FEUD values of up to 50% were observed in the 3D conformal plans. In addition, a non-small cell lung cancer patient was inversely planned with a target dose prescription of 76 Gy. Two IMRT plans (plan-A and plan-B) were generated for the patient based on the CT, FDG-PET and SPECT treatment planning images using dose-volume objective functions. The IMRT plans were generated with the goal of achieving more critical structures sparing in plan-B than plan-A. Results show the target volume EUD in plan-B is lower than plan-A by 5% with a value of 73.31 Gy, and the FEUD in plan-B is lower than plan-A by 2.6% with a value of 75.77 Gy. The FEUD plan-B values for heart and lungs were lower than plan-A by 22% and 18%, respectively

  8. In vivo skin dose measurement using MOSkin detectors in tangential breast radiotherapy.

    PubMed

    Jong, W L; Ung, N M; Wong, J H D; Ng, K H; Wan Ishak, W Z; Abdul Malik, R; Phua, V C E; Cutajar, D L; Metcalfe, P E; Rosenfeld, A B; Ho, G F

    2016-11-01

    The purpose of this study is to measure patient skin dose in tangential breast radiotherapy. Treatment planning dose calculation algorithm such as Pencil Beam Convolution (PBC) and in vivo dosimetry techniques such as radiochromic film can be used to accurately monitor radiation doses at tissue depths, but they are inaccurate for skin dose measurement. A MOSFET-based (MOSkin) detector was used to measure skin dose in this study. Tangential breast radiotherapies ("bolus" and "no bolus") were simulated on an anthropomorphic phantom and the skin doses were measured. Skin doses were also measured in 13 patients undergoing each of the techniques. In the patient study, the EBT2 measurements and PBC calculation tended to over-estimate the skin dose compared with the MOSkin detector (p<0.05) in the "no bolus radiotherapy". No significant differences were observed in the "bolus radiotherapy" (p>0.05). The results from patients were similar to that of the phantom study. This shows that the EBT2 measurement and PBC calculation, while able to predict accurate doses at tissue depths, are inaccurate in predicting doses at build-up regions. The clinical application of the MOSkin detectors showed that the average total skin doses received by patients were 1662±129cGy (medial) and 1893±199cGy (lateral) during "no bolus radiotherapy". The average total skin doses were 4030±72cGy (medial) and 4004±91cGy (lateral) for "bolus radiotherapy". In some cases, patient skin doses were shown to exceed the dose toxicity level for skin erythema. Hence, a suitable device for in vivo dosimetry is necessary to accurately determine skin dose. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  9. A response function calculation for a dose-equivalent neutron dosimeter using superheated drops

    SciTech Connect

    Wang, C.K. )

    1991-01-01

    A neutron dosimeter using superheated drops in gel was invented by Apfel. The SDD-100 or BD-100, which uses Freon-12 (CF{sub 2}Cl{sub 2}) for the superheated drops, is most useful in neutron dosimetry because it was claimed that the neutron response function of such a dosimeter is nearly dose equivalent. An ideal dose-equivalent neutron dosimeter should be totally independent of the energies of incident neutrons. Lo and Apfel have performed calculations and experiments to study the neutron response functions for various types of superheated drops, including Freon-12. Both their calculational and the experimental results demonstrated the dose-equivalent-like response function for the Freon-12. The agreement between the calculational results and the experimental results is not satisfactory, however, especially for neutrons with energies < 100 keV. One important factor, which was not considered and may have contributed to the disagreement, is the neutron-slowing-down effect. That is, kilo-electron-volt neutrons, although not energetic enough to trigger bubbles in Freon-12, have a short mean-free-path (< 1 cm) and can easily slow down or thermalize in the gel matrix and then trigger bubbles in Freon-12 via a {sup 35}Cl(n,p){sup 35}S reaction. To consider the slowing-down effect in the dosimeter, a neutron transport calculation must be performed. This paper describes the set of Monte Carlo neutron transport calculations that were performed to calculate the response function for a bare SDD-100 surrounded with various thicknesses of polyethylene (CH{sub 2}).

  10. Determination of the cosmic-ray-induced neutron flux and ambient dose equivalent at flight altitude

    NASA Astrophysics Data System (ADS)

    Pazianotto, M. T.; Cortés-Giraldo, M. A.; Federico, C. A.; Gonçalez, O. L.; Quesada, J. M.; Carlson, B. V.

    2015-07-01

    There is interest in modeling the atmosphere in the South Atlantic Magnetic Anomaly in order to obtain information about the cosmic-ray induced neutron spectrum and angular distribution as functions of altitude. In this work we use the Monte Carlo codes MCNPX and Geant4 to determine the cosmic-ray-induced neutron flux in the atmosphere produced by the cosmic ray protons incident on the top of the atmosphere and to estimate the ambient dose equivalent rate as function of altitude. The results present a reasonable conformity to other codes (QARM and EXPACS) based on other parameterizations.

  11. Out-of-field photon and neutron dose equivalents from step-and-shoot intensity-modulated radiation therapy

    SciTech Connect

    Kry, Stephen F.; Salehpour, Mohammad . E-mail: msalehpour@mdanderson.org; Followill, David S.; Stovall, Marilyn; Kuban, Deborah A.; White, R. Allen; Rosen, Isaac I.

    2005-07-15

    Purpose: To measure the photon and neutron out-of-treatment-field dose equivalents to various organs from different treatment strategies (conventional vs. intensity-modulated radiation therapy [IMRT]) at different treatment energies and delivered by different accelerators. Methods and Materials: Independent measurements were made of the photon and neutron out-of-field dose equivalents resulting from one conventional and six IMRT treatments for prostate cancer. The conventional treatment used an 18-MV beam from a Clinac 2100; the IMRT treatments used 6-MV, 10-MV, 15-MV, and 18-MV beams from a Varian Clinac 2100 accelerator and 6-MV and 15-MV beams from a Siemens Primus accelerator. Photon doses were measured with thermoluminescent dosimeters in a Rando phantom, and neutron fluence was measured with gold foils. Dose equivalents to the colon, liver, stomach, lung, esophagus, thyroid, and active bone marrow were determined for each treatment approach. Results: For each treatment approach, the relationship between dose equivalent per MU, distance from the treatment field, and depth in the patient was examined. Photon dose equivalents decreased approximately exponentially with distance from the treatment field. Neutron dose equivalents were independent of distance from the treatment field and decreased with increasing tissue depth. Neutrons were a significant contributor to the out-of field dose equivalent for beam energies {>=}15 MV. Conclusions: Out-of-field photon and neutron dose equivalents can be estimated to any point in a patient undergoing a similar treatment approach from the distance of that point to the central axis and from the tissue depth. This information is useful in determining the dose to critical structures and in evaluating the risk of associated carcinogenesis.

  12. Natural radioactivity and evaluation of effective dose equivalent of granites in Turkey.

    PubMed

    Osmanlioglu, Ahmet Erdal

    2006-01-01

    Annual effective dose equivalent due to natural gamma radiation from (238)U, (232)Th and (40)K have been evaluated from granites in Turkey. Forty samples were taken for spectrometric analysis. Specific concentrations of (238)U, (232)Th and (40)K in granite samples were determined. Spectroscopy system was used with 1.8 keV (FWHM) coaxial high purity germanium (HPGe) detector. Average values of concentrations of (238)U, (232)Th and (40)K were detected at 15.85, 33.76 and 359 Bq kg(-1), respectively. The average value of radon varies from 0.073 to 0.185 Bq m(-2) h(-1) exhalation depends on the specific concentration of uranium. The dose rate due to this highest activity which have been evaluated by a Monte Carlo transport calculations does not exceed 0.4 mSv a(-1).

  13. Predictive ability of reconstructed human epidermis equivalents for the assessment of skin irritation of cosmetics.

    PubMed

    Faller, C; Bracher, M; Dami, N; Roguet, R

    2002-10-01

    The aim of this study was to examine the concordance between human in vivo and in vitro skin irritation classifications of cosmetic products and to evaluate the correlations between the different parameters. For that purpose, 22 formulations from product development test series, covering the full range of in vivo scores and representing different cosmetic product classes, were tested in vivo (modified Frosch-Kligman Soap Chamber Patch Test with repetitive occlusive application) and in vitro using two epidermis equivalents commercially available as kits (EpiDerm and EPISKIN) and one in-house model (Cosmital). In vivo, skin reactions (erythema, dryness and fissures) were visually evaluated and, in addition, skin redness and transepidermal water loss (TEWL) were measured by means of technical instruments. The parameters measured in vitro were the percent cell viability in the MTT reduction assay, with ET(50) determination, and the extracellular release of the pro-inflammatory mediator IL-1alpha and of the cytosolic enzyme lactate dehydrogenase (LDH), into the culture medium collected after topical application of the products for different exposure times (time-course assay). In general, good Spearman rank correlations could be observed between the different in vivo parameters (with the exception of TEWL and dryness at day 2). Furthermore, high correlation coefficients were obtained by comparing the different in vitro parameters (except for LDH release) and different models, which allowed to conclude that the results obtained with the different reconstructed epidermis models were very similar. A comparison between in vivo and in vitro parameters resulted in the best rank correlation for ET(50), then in decreasing order, for the percent MTT viability at 16 h, the IL-1alpha release and finally, for LDH release, where the correlation was generally low. A direct comparison of the mean total scores (sum of erythema, dryness and fissures at day 5) of the 22 products with the

  14. Neutron yield and dose equivalent from heavy ion interactions on thick target

    NASA Astrophysics Data System (ADS)

    Sunil, C.; Saxena, A.; Choudhury, R. K.; Pant, L. M.

    2004-12-01

    Thick target neutron yields and angular distributions are essential for shielding calculations for ion beam accelerators. Most of such measurements available in the literature are for proton and alpha particle bombardments. In case of heavy ions, very few data are available in the energy region of 20 MeV amu -1 and below. We report here the neutron yield, double differential neutron yields and neutron dose equivalent values obtained from the double differential yields at 0° and 90° with respect to the beam for various heavy ions in the energy range of 3.5-7.0 MeV amu -1. Pulse shape discrimination was used to separate neutrons from gamma rays and time of flight technique was used for energy measurement. The double differential neutron yields were fitted using the moving source model and the nuclear temperature and source intensity are also determined. The neutron yield increases inversely with the mass of the projectile except in the case of 7Li where the yields are much lower than that obtained from 11B. This could be due to the structure of the loosely bound 7Li projectile. The neutron dose equivalent shows increasing trend with the decrease of the mass of the projectile.

  15. Spatial analysis of ambient gamma dose equivalent rate data by means of digital image processing techniques.

    PubMed

    Szabó, Katalin Zsuzsanna; Jordan, Gyozo; Petrik, Attila; Horváth, Ákos; Szabó, Csaba

    2017-01-01

    A detailed ambient gamma dose equivalent rate mapping based on field measurements at ground level and at 1 m height was carried out at 142 sites in 80 × 90 km area in Pest County, Hungary. Detailed digital image processing analysis was carried out to identify and characterise spatial features such as outlying points, anomalous zones and linear edges in a smoothed TIN interpolated surface. The applied method proceeds from the simple shaded relief model and digital cross-sections to the more complex gradient magnitude and gradient direction maps, 2nd derivative profile curvature map, relief map and lineament density map. Each map is analysed for statistical characteristics and histogram-based image segmentation is used to delineate areas homogeneous with respect to the parameter values in these maps. Assessment of spatial anisotropy is implemented by 2D autocorrelogram and directional variogram analyses. The identified spatial features are related to underlying geological and tectonic conditions using GIS technology. Results show that detailed digital image processing is efficient in revealing the pattern present in field-measured ambient gamma dose equivalent rates and they are related to regional scale tectonic zones and surface sedimentary lithological conditions in the study area. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Characterization of a Human Skin Equivalent Model to Study the Effects of Ultraviolet B Radiation on Keratinocytes

    PubMed Central

    Van Lonkhuyzen, Derek R.; Dawson, Rebecca A.; Kimlin, Michael G.; Upton, Zee

    2014-01-01

    The incidences of skin cancers resulting from chronic ultraviolet radiation (UVR) exposure are on the incline in both Australia and globally. Hence, the cellular and molecular pathways that are associated with UVR-induced photocarcinogenesis need to be urgently elucidated, in order to develop more robust preventative and treatment strategies against skin cancers. In vitro investigations into the effects of UVR (in particular, the highly mutagenic UVB wavelength) have, to date, mainly involved the use of cell culture and animal models. However, these models possess biological disparities to native skin, which, to some extent, have limited their relevance to the in vivo situation. To address this, we characterized a three-dimensional, tissue-engineered human skin equivalent (HSE) model (consisting of primary human keratinocytes cultured on a dermal-derived scaffold) as a representation of a more physiologically relevant platform to study keratinocyte responses to UVB. Significantly, we demonstrate that this model retains several important epidermal properties of native skin. Moreover, UVB irradiation of the HSE constructs was shown to induce key markers of photodamage in the HSE keratinocytes, including the formation of cyclobutane pyrimidine dimers, the activation of apoptotic pathways, the accumulation of p53, and the secretion of inflammatory cytokines. Importantly, we also demonstrate that the UVB-exposed HSE constructs retain the capacity for epidermal repair and regeneration after photodamage. Together, our results demonstrate the potential of this skin equivalent model as a tool to study various aspects of the acute responses of human keratinocytes to UVB radiation damage. PMID:24219750

  17. Cellular response of the rat brain to single doses of (137)Cs γ rays does not predict its response to prolonged 'biologically equivalent' fractionated doses.

    PubMed

    Greene-Schloesser, Dana M; Kooshki, Mitra; Payne, Valerie; D'Agostino, Ralph B; Wheeler, Kenneth T; Metheny-Barlow, Linda J; Robbins, Mike E

    2014-09-01

    To determine if the brain's response to single doses predicts its response to 'biologically equivalent' fractionated doses. Young adult male Fischer 344 rats were whole-brain irradiated with either single 11, 14, or 16.5 Gy doses of (137)Cs γ rays or their 'biologically equivalent' 20, 30, or 40 Gy fractionated doses (fWBI) delivered in 5 Gy fractions, twice/week for 2, 3, or 4 weeks, respectively. At 2 months post-irradiation, cellular markers of inflammation (total, activated, and newborn microglia) and neurogenesis (newborn neurons) were measured in 40 μm sections of the dentate gyrus (DG). Although the total number of microglia in the DG/hilus was not significantly different (p > 0.7) in unirradiated, single dose, and fWBI rats, single doses produced a significant (p < 0.003) increase in the percent-activated microglia; fWBI did not (p > 0.1). Additionally, single doses produced a significant (p < 0.002) dose-dependent increase in surviving newborn microglia; fWBI did not (p < 0.8). Although total proliferation in the DG was reduced equally by single and fWBI doses, single doses produced a significant dose-dependent (p < 0.02) decrease in surviving newborn neurons; fWBI did not (p > 0.6). These data demonstrate that the rat brain's cellular response to single doses often does not predict its cellular response to 'biologically equivalent' fWBI doses.

  18. 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.

  19. Switch from epoetin to darbepoetin alfa in hemodialysis: dose equivalence and hemoglobin stability

    PubMed Central

    Arrieta, Javier; Moina, Iñigo; Molina, José; Gallardo, Isabel; Muñiz, María Luisa; Robledo, Carmen; García, Oscar; Vidaur, Fernando; Muñoz, Rosa Inés; Iribar, Izaskun; Aguirre, Román; Maza, Antonio

    2014-01-01

    Aim The objective of the study reported here was to describe dose equivalence and hemoglobin (Hb) stability in a cohort of unselected hemodialysis patients who were switched simultaneously from epoetin alfa to darbepoetin alfa. Methods This was a multicenter, observational, retrospective study in patients aged ≥18 years who switched from intravenous (IV) epoetin alfa to IV darbepoetin alfa in October 2007 (Month 0) and continued on hemodialysis for at least 24 months. The dose was adjusted to maintain Hb within 1.0 g/dL of baseline. Results We included 125 patients (59.7% male, mean [standard deviation (SD)] age 70.4 [13.4] years). No significant changes were observed in Hb levels (mean [SD] 11.9 [1.3] g/dL, 12.0 [1.5], 12.0 [1.5], and 12.0 [1.7] at Months −12, 0, 12 and 24, respectively, P=0.409). After conversion, the erythropoiesis-stimulating agent (ESA) dose decreased significantly (P<0.0001), with an annual mean of 174.7 (88.7) international units (IU)/kg/week for epoetin versus 95.7 (43.4) (first year) and 91.4 (42.7) IU/kg/week (second year) for darbepoetin (65% and 64% reduction, respectively). The ESA resistance index decreased from 15.1 (8.5) IU/kg/week/g/dL with epoetin to 8.1 (3.9) (first year) and 7.9 (4.0) (second year) with darbepoetin (P<0.0001). The conversion rate was 354:1 in patients requiring high (>200 IU/kg/week) doses of epoetin and 291:1 in patients requiring low doses. Conclusion In patients on hemodialysis receiving ESAs, conversion from epoetin alfa to darbepoetin alfa was associated with an approximate and persistent reduction of 65% of the required dose. To maintain Hb stability, a conversion rate of 300:1 seems to be appropriate for most patients receiving low doses of epoetin alfa (≤200 IU/kg/week), while 350:1 would be better for patients receiving higher doses. PMID:25336984

  20. Low-dose UVB irradiation prevents MMP2-induced skin hyperplasia by inhibiting inflammation and ROS.

    PubMed

    Dang, Lin; Wang, Yan; Xue, Yadong; He, Lei; Li, Yuzhen; Xiong, Jikui

    2015-09-01

    Skin cancer is one of the most common types of malignancy in the world. UV radiation is known as the primary environmental carcinogen responsible for skin cancer development. However, UV radiation is a ubiquitous substance existing in the environment and the physiological effect of UV radiation is consistently ignored. Therefore, in the present study, the physiological effect of UV radiation on inhibition of skin cancer was investigated. Normal mouse skin was processing by no pre-radiation or pre-radiation of low-dose UV before a medium or high dose of UV radiation. We found that the low-dose pre-radiated mouse skin tissue exhibited low skin inflammation, skin ROS production and consequently low skin epithelial hyperplasia after the medium-dose UV radiation compared with the no pre-radiated mouse. However, this inhibition was not indicated in the high-dose UV radiation group after low-dose pre-radiation. Furthermore, western blot analysis and gelatin zymography showed low expression and activation of MMP2 in the skin tissues processed following medium-dose radiation, but not in tissues treated with high-dose radiation after a low-dose pre-radiation. Further investigation of MMP2 inhibitors of TIMP2/TIMP4 showed an upregulated TIMP2 expression, but not TIMP4. Collectively, these data indicate that low-dose pre-radiation attenuates the skin inflammation and ROS production induced by medium-dose UV radiation and also elevates TIMP2 to withstand MMP2, therefore suppressing skin hyperplasia. The present study indicates a novel concept or prophylactic function of moderate UV radiation as a preventative strategy.

  1. LL-37-Derived Peptides Eradicate Multidrug-Resistant Staphylococcus aureus from Thermally Wounded Human Skin Equivalents

    PubMed Central

    de Breij, Anna; Chan, Heelam; van Dissel, Jaap T.; Drijfhout, Jan W.; Hiemstra, Pieter S.; El Ghalbzouri, Abdoelwaheb; Nibbering, Peter H.

    2014-01-01

    Burn wound infections are often difficult to treat due to the presence of multidrug-resistant bacterial strains and biofilms. Currently, mupirocin is used to eradicate methicillin-resistant Staphylococcus aureus (MRSA) from colonized persons; however, mupirocin resistance is also emerging. Since we consider antimicrobial peptides to be promising candidates for the development of novel anti-infective agents, we studied the antibacterial activities of a set of synthetic peptides against different strains of S. aureus, including mupirocin-resistant MRSA strains. The peptides were derived from P60.4Ac, a peptide based on the human cathelicidin LL-37. The results showed that peptide 10 (P10) was the only peptide more efficient than P60.4Ac, which is better than LL-37, in killing MRSA strain LUH14616. All three peptides displayed good antibiofilm activities. However, both P10 and P60.4Ac were more efficient than LL-37 in eliminating biofilm-associated bacteria. No toxic effects of these three peptides on human epidermal models were detected, as observed morphologically and by staining for mitochondrial activity. In addition, P60.4Ac and P10, but not LL-37, eradicated MRSA LUH14616 and the mupirocin-resistant MRSA strain LUH15051 from thermally wounded human skin equivalents (HSE). Interestingly, P60.4Ac and P10, but not mupirocin, eradicated LUH15051 from the HSEs. None of the peptides affected the excretion of interleukin 8 (IL-8) by thermally wounded HSEs upon MRSA exposure. In conclusion, the synthetic peptides P60.4Ac and P10 appear to be attractive candidates for the development of novel local therapies to treat patients with burn wounds infected with multidrug-resistant bacteria. PMID:24841266

  2. LL-37-derived peptides eradicate multidrug-resistant Staphylococcus aureus from thermally wounded human skin equivalents.

    PubMed

    Haisma, Elisabeth M; de Breij, Anna; Chan, Heelam; van Dissel, Jaap T; Drijfhout, Jan W; Hiemstra, Pieter S; El Ghalbzouri, Abdoelwaheb; Nibbering, Peter H

    2014-08-01

    Burn wound infections are often difficult to treat due to the presence of multidrug-resistant bacterial strains and biofilms. Currently, mupirocin is used to eradicate methicillin-resistant Staphylococcus aureus (MRSA) from colonized persons; however, mupirocin resistance is also emerging. Since we consider antimicrobial peptides to be promising candidates for the development of novel anti-infective agents, we studied the antibacterial activities of a set of synthetic peptides against different strains of S. aureus, including mupirocin-resistant MRSA strains. The peptides were derived from P60.4Ac, a peptide based on the human cathelicidin LL-37. The results showed that peptide 10 (P10) was the only peptide more efficient than P60.4Ac, which is better than LL-37, in killing MRSA strain LUH14616. All three peptides displayed good antibiofilm activities. However, both P10 and P60.4Ac were more efficient than LL-37 in eliminating biofilm-associated bacteria. No toxic effects of these three peptides on human epidermal models were detected, as observed morphologically and by staining for mitochondrial activity. In addition, P60.4Ac and P10, but not LL-37, eradicated MRSA LUH14616 and the mupirocin-resistant MRSA strain LUH15051 from thermally wounded human skin equivalents (HSE). Interestingly, P60.4Ac and P10, but not mupirocin, eradicated LUH15051 from the HSEs. None of the peptides affected the excretion of interleukin 8 (IL-8) by thermally wounded HSEs upon MRSA exposure. In conclusion, the synthetic peptides P60.4Ac and P10 appear to be attractive candidates for the development of novel local therapies to treat patients with burn wounds infected with multidrug-resistant bacteria.

  3. MUTZ-3 derived Langerhans cells in human skin equivalents show differential migration and phenotypic plasticity after allergen or irritant exposure.

    PubMed

    Kosten, Ilona J; Spiekstra, Sander W; de Gruijl, Tanja D; Gibbs, Susan

    2015-08-15

    After allergen or irritant exposure, Langerhans cells (LC) undergo phenotypic changes and exit the epidermis. In this study we describe the unique ability of MUTZ-3 derived Langerhans cells (MUTZ-LC) to display similar phenotypic plasticity as their primary counterparts when incorporated into a physiologically relevant full-thickness skin equivalent model (SE-LC). We describe differences and similarities in the mechanisms regulating LC migration and plasticity upon allergen or irritant exposure. The skin equivalent consisted of a reconstructed epidermis containing primary differentiated keratinocytes and CD1a(+) MUTZ-LC on a primary fibroblast-populated dermis. Skin equivalents were exposed to a panel of allergens and irritants. Topical exposure to sub-toxic concentrations of allergens (nickel sulfate, resorcinol, cinnamaldehyde) and irritants (Triton X-100, SDS, Tween 80) resulted in LC migration out of the epidermis and into the dermis. Neutralizing antibody to CXCL12 blocked allergen-induced migration, whereas anti-CCL5 blocked irritant-induced migration. In contrast to allergen exposure, irritant exposure resulted in cells within the dermis becoming CD1a(-)/CD14(+)/CD68(+) which is characteristic of a phenotypic switch of MUTZ-LC to a macrophage-like cell in the dermis. This phenotypic switch was blocked with anti-IL-10. Mechanisms previously identified as being involved in LC activation and migration in native human skin could thus be reproduced in the in vitro constructed skin equivalent model containing functional LC. This model therefore provides a unique and relevant research tool to study human LC biology in situ under controlled in vitro conditions, and will provide a powerful tool for hazard identification, testing novel therapeutics and identifying new drug targets.

  4. Integration of Mature Adipocytes to Build-Up a Functional Three-Layered Full-Skin Equivalent

    PubMed Central

    Huber, Birgit; Link, Antonia; Linke, Kirstin; Gehrke, Sandra A.; Winnefeld, Marc

    2016-01-01

    Large, deep full-thickness skin wounds from high-graded burns or trauma are not able to reepithelialize sufficiently, resulting in scar formation, mobility limitations, and cosmetic deformities. In this study, in vitro-constructed tissue replacements are needed. Furthermore, such full-skin equivalents would be helpful as in vivo-like test systems for toxicity, cosmetic, and pharmaceutical testing. Up to date, no skin equivalent is available containing the underlying subcutaneous fatty tissue. In this study, we composed a full-skin equivalent and evaluated three different media for the coculture of mature adipocytes, fibroblasts, and keratinocytes. Therefore, adipocyte medium was supplemented with ascorbyl-2-phosphate and calcium chloride, which are important for successful epidermal stratification (Air medium). This medium was further supplemented with two commercially available factor combinations often used for the in vitro culture of keratinocytes (Air-HKGS and Air-KGM medium). We showed that in all media, keratinocytes differentiated successfully to build a stratified epidermal layer and expressed cytokeratin 10 and 14. Perilipin A-positive adipocytes could be found in all tissue models for up to 14 days, whereas adipocytes in the Air-HKGS and Air-KGM medium seemed to be smaller. Adipocytes in all tissue models were able to release adipocyte-specific factors, whereas the supplementation of keratinocyte-specific factors had a slightly negative effect on adipocyte functionality. The permeability of the epidermis of all models was comparable since they were able to withstand a deep penetration of cytotoxic Triton X in the same manner. Taken together, we were able to compose functional three-layered full-skin equivalents by using the Air medium. PMID:27334067

  5. Integration of Mature Adipocytes to Build-Up a Functional Three-Layered Full-Skin Equivalent.

    PubMed

    Huber, Birgit; Link, Antonia; Linke, Kirstin; Gehrke, Sandra A; Winnefeld, Marc; Kluger, Petra J

    2016-08-01

    Large, deep full-thickness skin wounds from high-graded burns or trauma are not able to reepithelialize sufficiently, resulting in scar formation, mobility limitations, and cosmetic deformities. In this study, in vitro-constructed tissue replacements are needed. Furthermore, such full-skin equivalents would be helpful as in vivo-like test systems for toxicity, cosmetic, and pharmaceutical testing. Up to date, no skin equivalent is available containing the underlying subcutaneous fatty tissue. In this study, we composed a full-skin equivalent and evaluated three different media for the coculture of mature adipocytes, fibroblasts, and keratinocytes. Therefore, adipocyte medium was supplemented with ascorbyl-2-phosphate and calcium chloride, which are important for successful epidermal stratification (Air medium). This medium was further supplemented with two commercially available factor combinations often used for the in vitro culture of keratinocytes (Air-HKGS and Air-KGM medium). We showed that in all media, keratinocytes differentiated successfully to build a stratified epidermal layer and expressed cytokeratin 10 and 14. Perilipin A-positive adipocytes could be found in all tissue models for up to 14 days, whereas adipocytes in the Air-HKGS and Air-KGM medium seemed to be smaller. Adipocytes in all tissue models were able to release adipocyte-specific factors, whereas the supplementation of keratinocyte-specific factors had a slightly negative effect on adipocyte functionality. The permeability of the epidermis of all models was comparable since they were able to withstand a deep penetration of cytotoxic Triton X in the same manner. Taken together, we were able to compose functional three-layered full-skin equivalents by using the Air medium.

  6. Measurement of dose equivalent distribution on-board commercial jet aircraft.

    PubMed

    Kubančák, J; Ambrožová, I; Ploc, O; Pachnerová Brabcová, K; Štěpán, V; Uchihori, Y

    2014-12-01

    The annual effective doses of aircrew members often exceed the limit of 1 mSv for the public due to the increased level of cosmic radiation at the flight altitudes, and thus, it is recommended to monitor them [International Commission on Radiation Protection. 1990 Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Ann. ICRP 21: (1-3), (1991)]. According to the Monte Carlo simulations [Battistoni, G., Ferrari, A., Pelliccioni, M. and Villari, R. Evaluation of the doses to aircrew members taking into consideration the aircraft structures. Adv. Space Res. 36: , 1645-1652 (2005) and Ferrari, A., Pelliccioni, M. and Villari, R. Evaluation of the influence of aircraft shielding on the aircrew exposure through an aircraft mathematical model. Radiat. Prot. Dosim. 108: (2), 91-105 (2004)], the ambient dose equivalent rate Ḣ*(10) depends on the location in the aircraft. The aim of this article is to experimentally evaluate Ḣ*(10) on-board selected types of aircraft. The authors found that Ḣ*(10) values are higher in the front and the back of the cabin and lesser in the middle of the cabin. Moreover, total dosimetry characteristics obtained in this way are in a reasonable agreement with other data, in particular with the above-mentioned simulations. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Vibrational spectroscopy and microscopic imaging: novel approaches for comparing barrier physical properties in native and human skin equivalents

    NASA Astrophysics Data System (ADS)

    Yu, Guo; Zhang, Guojin; Flach, Carol R.; Mendelsohn, Richard

    2013-06-01

    Vibrational spectroscopy and imaging have been used to compare barrier properties in human skin, porcine skin, and two human skin equivalents, Epiderm 200X with an enhanced barrier and Epiderm 200 with a normal barrier. Three structural characterizations were performed. First, chain packing and conformational order were compared in isolated human stratum corneum (SC), isolated porcine SC, and in the Epiderm 200X surface layers. The infrared (IR) spectrum of isolated human SC revealed a large proportion of orthorhombically packed lipid chains at physiological temperatures along with a thermotropic phase transition to a state with hexagonally packed chains. In contrast, the lipid phase at physiological temperatures in both porcine SC and in Epiderm 200X, although dominated by conformationally ordered chains, lacked significant levels of orthorhombic subcell packing. Second, confocal Raman imaging of cholesterol bands showed extensive formation of cholesterol-enriched pockets within the human skin equivalents (HSEs). Finally, IR imaging tracked lipid barrier dimensions as well as the spatial disposition of ordered lipids in human SC and Epiderm 200X. These approaches provide a useful set of experiments for exploring structural differences between excised human skin and HSEs, which in turn may provide a rationale for the functional differences observed among these preparations.

  8. Estimation of the radiation dose from radiotherapy for skin haemangiomas in childhood: the ICTA software for epidemiology

    NASA Astrophysics Data System (ADS)

    Shamsaldin, A.; Lundell, M.; Diallo, I.; Ligot, L.; Chavaudra, J.; de Vathaire, F.

    2000-12-01

    Radium applicators and pure beta emitters have been widely used in the past to treat skin haemangioma in early childhood. A well defined relationship between the low doses received from these applicators and radiation-induced cancers requires accurate dosimetry. A human-based CT scan phantom has been used to simulate every patient and treatment condition and then to calculate the source-target distance when radium and pure beta applicators were used. The effective transmission factor ϕ(r) for the gamma spectrum emitted by the radium sources applied on the skin surface was modelled using Monte Carlo simulations. The well-known quantization approach was used to calculate gamma doses delivered from radium applicators to various anatomical points. For 32P, 90Sr/90Y applicators and 90Y needles we have used the apparent exponential attenuation equation. The dose calculation algorithm was integrated into the ICTA software (standing for a model that constructs an Individualized phantom based on CT slices and Auxological data), which has been developed for epidemiological studies of cohorts of patients who received radium and beta-treatments for skin haemangioma. The ϕ(r) values obtained for radium skin applicators are in good agreement with the available values in the first 10 cm but higher at greater distances. Gamma doses can be calculated with this algorithm at 165 anatomical points throughout the body of patients treated with radium applicators. Lung heterogeneity and air crossed by the gamma rays are considered. Comparison of absorbed doses in water from a 10 mg equivalent radium source simulated by ICTA with those measured at the Radiumhemmet, Karolinska Hospital (RAH) showed good agreement, but ICTA estimation of organ doses did not always correspond those estimated at the RAH. Beta doses from 32P, 90Sr/90Y applicators and 90Y needles are calculated up to the maximum beta range (11 mm).

  9. Megavoltage x-ray skin dose variation with an angle using grid carbon fibre couch tops.

    PubMed

    Butson, Martin J; Cheung, Tsang; Yu, Peter K N

    2007-10-21

    It is well known that a skin dose from high-energy x-ray radiation varies with the angle of beam incidence or the presence of a radiotherapy linear accelerator couch top material. This note investigates changes produced to the skin dose from a Varian carbon fibre grid couch top at differing angles of incidence for 6 MV x-rays as is often the case clinically. Results have shown that the skin dose can easily be measured using an EBT Gafchromic film whereby the delivered skin dose can be quantified to a high level of spatial resolution, not easily achieved with other skin dose detectors. Results have shown a significant increase in the skin dose specifically at the point of a cross-sectional carbon fibre grid. Values in % of the skin dose increased from approximately 27% (an open area within a 10 cm x 10 cm field) up to 55% (same field size) at the centre of the carbon fibre mesh strip (0 degrees incidence). This is compared to 19% of the skin dose for an open field of a 10 cm x 10 cm beam without the couch material present. At larger angles similar effects occur with values changing from 52% to 75% (60 degrees , 10 cm x 10 cm) in the open area and under the grid, respectively. This produces a wave effect for the skin dose. The average skin dose magnitude increases with the angle of incidence of the beam, ranging from 37.5% to 66% from 0 degrees to 60 degrees (10 x 10 cm), respectively. The symmetric wave nature of the skin dose profile skews to deliver an increased dose on the posterior side of the carbon fibre grid as the angle of incidence increases. Simulated fractional dose delivery on a phantom has shown that over 30 fractions the wave nature of the delivered skin dose is minimized due to the random nature of most patient positioning on the treatment couch. However, some variations are still present as the ratio of the open to grid area is approximately 4:1 and the dose spread is not necessarily completely averaged during a typical fractionated radiotherapy

  10. Simulation studies on a prototype ionisation chamber for measurement of personal dose equivalent, Hp(10).

    PubMed

    Cardoso, J; Carvalho, A F; Oliveira, C

    2007-01-01

    A prototype ionisation chamber for direct measurement of the personal dose equivalent, Hp(10), similar to the one developed by the Physikalisch-Technische Bundesantalt (PTB), was designed and constructed by the Metrological Laboratory of Ionizing Radiation (LMRI) of Nuclear and Technological Institute (ITN). Tests already performed have shown that the behaviour of this chamber is very similar to the PTB chamber, mainly the energy dependence for the X-ray radiation qualities of the ISO 4037-1 narrow series N-30, N-40, N-60, N-80, N-100 and N-120 and also for gamma radiation of 137Cs and 60Co. However, the results obtained also show a dependence on the energy and angles of incident radiation and a low magnitude of the electrical response of the ionisation chamber. In order to optimise the performance of the chamber, the LMRI initiated numerical simulation of this ionisation chamber by Monte Carlo method using the MCNPX code.

  11. Investigation of real tissue water equivalent path lengths using an efficient dose extinction method

    NASA Astrophysics Data System (ADS)

    Zhang, Rongxiao; Baer, Esther; Jee, Kyung-Wook; Sharp, Gregory C.; Flanz, Jay; Lu, Hsiao-Ming

    2017-07-01

    For proton therapy, an accurate conversion of CT HU to relative stopping power (RSP) is essential. Validation of the conversion based on real tissue samples is more direct than the current practice solely based on tissue substitutes and can potentially address variations over the population. Based on a novel dose extinction method, we measured water equivalent path lengths (WEPL) on animal tissue samples to evaluate the accuracy of CT HU to RSP conversion and potential variations over a population. A broad proton beam delivered a spread out Bragg peak to the samples sandwiched between a water tank and a 2D ion-chamber detector. WEPLs of the samples were determined from the transmission dose profiles measured as a function of the water level in the tank. Tissue substitute inserts and Lucite blocks with known WEPLs were used to validate the accuracy. A large number of real tissue samples were measured. Variations of WEPL over different batches of tissue samples were also investigated. The measured WEPLs were compared with those computed from CT scans with the Stoichiometric calibration method. WEPLs were determined within  ±0.5% percentage deviation (% std/mean) and  ±0.5% error for most of the tissue surrogate inserts and the calibration blocks. For biological tissue samples, percentage deviations were within  ±0.3%. No considerable difference (<1%) in WEPL was observed for the same type of tissue from different sources. The differences between measured WEPLs and those calculated from CT were within 1%, except for some bony tissues. Depending on the sample size, each dose extinction measurement took around 5 min to produce ~1000 WEPL values to be compared with calculations. This dose extinction system measures WEPL efficiently and accurately, which allows the validation of CT HU to RSP conversions based on the WEPL measured for a large number of samples and real tissues.

  12. Variations of the ambient dose equivalent rate in the ground level air.

    PubMed

    Lebedyte, M; Butkus, D; Morkŭnas, G

    2003-01-01

    The ambient dose equivalent rate is caused by ionizing radiation of radionuclides in the atmosphere and on the ground surface as well as by cosmic radiation. Seasonal and diurnal variations of the ambient dose equivalent rate (ADER) in the ground level air are influenced by the concentration of 222Rn daughters. The 222Rn concentration in the ground level atmosphere, in turn, depends on the rate of the 222Rn exhalation from soil and turbulent air mixing. Its diurnal and seasonal variations depend on meteorological conditions. The aim of this study is to estimate the influence of variations of the rate of the 222Rn exhalation from soil and its concentrations in the ground level air on variations of ADER in the ground level air, as well as the dependence of these parameters on meteorological conditions. The 222Rn diffusion coefficient and its exhalation rate in undisturbed loamy soil have been determined. The 222Rn concentration in the soil air and its concentration in the ground level air correlate inversely (correlation coefficient is r = -0.62). The main factors determining the 222Rn exhalation from soil are: the soil temperature (r = 0.64), the difference in temperature of soil and air (r = 0.57), and the precipitation amount (r = 0.50). The intensity of gamma radiation in the ground level air is mostly related to the 222Rn concentration in the air (r = 0.62), while the effect of the exhalation rate from soil is relatively low (r = 0.36). It has been shown that ADER due to 222Rn progeny causes only 7-16% of the total ADER and influences its variation. The comparison of variations of ADER due to 222Rn progeny and the total ADER during several years shows that these parameters correlate positively.

  13. Development of a Full-Thickness Human Skin Equivalent In Vitro Model Derived from TERT-Immortalized Keratinocytes and Fibroblasts.

    PubMed

    Reijnders, Christianne M A; van Lier, Amanda; Roffel, Sanne; Kramer, Duco; Scheper, Rik J; Gibbs, Susan

    2015-09-01

    Currently, human skin equivalents (HSEs) used for in vitro assays (e.g., for wound healing) make use of primary human skin cells. Limitations of primary keratinocytes and fibroblasts include availability of donor skin and donor variation. The use of physiologically relevant cell lines could solve these limitations. The aim was to develop a fully differentiated HSE constructed entirely from human skin cell lines, which could be applied for in vitro wound-healing assays. Skin equivalents were constructed from human TERT-immortalized keratinocytes and fibroblasts (TERT-HSE) and compared with native skin and primary HSEs. HSEs were characterized by hematoxylin-eosin and immunohistochemical stainings with markers for epidermal proliferation and differentiation, basement membrane (BM), fibroblasts, and the extracellular matrix (ECM). Ultrastructure was determined with electron microscopy. To test the functionality of the TERT-HSE, burn and cold injuries were applied, followed by immunohistochemical stainings, measurement of reepithelialization, and determination of secreted wound-healing mediators. The TERT-HSE was composed of a fully differentiated epidermis and a fibroblast-populated dermis comparable to native skin and primary HSE. The epidermis consisted of proliferating keratinocytes within the basal layer, followed by multiple spinous layers, a granular layer, and cornified layers. Within the TERT-HSE, the membrane junctions such as corneosomes, desmosomes, and hemidesmosomes were well developed as shown by ultrastructure pictures. Furthermore, the BM consisted of a lamina lucida and lamina densa comparable to native skin. The dermal matrix of the TERT-HSE was more similar to native skin than the primary construct, since collagen III, an ECM marker, was present in TERT-HSEs and absent in primary HSEs. After wounding, the TERT-HSE was able to reepithelialize and secrete inflammatory wound-healing mediators. In conclusion, the novel TERT-HSE, constructed entirely

  14. Development of a Full-Thickness Human Skin Equivalent In Vitro Model Derived from TERT-Immortalized Keratinocytes and Fibroblasts

    PubMed Central

    Reijnders, Christianne M.A.; van Lier, Amanda; Roffel, Sanne; Kramer, Duco; Scheper, Rik J.

    2015-01-01

    Currently, human skin equivalents (HSEs) used for in vitro assays (e.g., for wound healing) make use of primary human skin cells. Limitations of primary keratinocytes and fibroblasts include availability of donor skin and donor variation. The use of physiologically relevant cell lines could solve these limitations. The aim was to develop a fully differentiated HSE constructed entirely from human skin cell lines, which could be applied for in vitro wound-healing assays. Skin equivalents were constructed from human TERT-immortalized keratinocytes and fibroblasts (TERT-HSE) and compared with native skin and primary HSEs. HSEs were characterized by hematoxylin–eosin and immunohistochemical stainings with markers for epidermal proliferation and differentiation, basement membrane (BM), fibroblasts, and the extracellular matrix (ECM). Ultrastructure was determined with electron microscopy. To test the functionality of the TERT-HSE, burn and cold injuries were applied, followed by immunohistochemical stainings, measurement of reepithelialization, and determination of secreted wound-healing mediators. The TERT-HSE was composed of a fully differentiated epidermis and a fibroblast-populated dermis comparable to native skin and primary HSE. The epidermis consisted of proliferating keratinocytes within the basal layer, followed by multiple spinous layers, a granular layer, and cornified layers. Within the TERT-HSE, the membrane junctions such as corneosomes, desmosomes, and hemidesmosomes were well developed as shown by ultrastructure pictures. Furthermore, the BM consisted of a lamina lucida and lamina densa comparable to native skin. The dermal matrix of the TERT-HSE was more similar to native skin than the primary construct, since collagen III, an ECM marker, was present in TERT-HSEs and absent in primary HSEs. After wounding, the TERT-HSE was able to reepithelialize and secrete inflammatory wound-healing mediators. In conclusion, the novel TERT-HSE, constructed entirely

  15. Toward a molecular equivalent dose: use of the medaka model in comparative risk assessment.

    PubMed

    Hobbie, Kristen R; Deangelo, Anthony B; King, Leon C; Winn, Richard N; Law, J McHugh

    2009-03-01

    Recent changes in the risk assessment landscape underscore the need to be able to compare the results of toxicity and dose-response testing between a growing list of animal models and, quite possibly, an array of in vitro screening assays. How do we compare test results for a given compound between vastly different species? For example, what dose level in the ambient water of a small fish model would be equivalent to 10 ppm of a given compound in the rat's drinking water? Where do we begin? To initially address these questions, and in order to compare dose-response tests in a standard rodent model with a fish model, we used the concept of molecular dose. Assays that quantify types of DNA damage that are directly relevant to carcinogenesis integrate the factors such as chemical exposure, uptake, distribution, metabolism, etc. that tend to vary so widely between different phyletic levels. We performed parallel exposures in F344 rats and Japanese medaka (Oryzias latipes) to the alkylating hepatocarcinogen, dimethylnitrosamine (DMN). In both models, we measured the DNA adducts 8-hydroxyguanine, N(7)-methylguanine and O(6)-methylguanine in the liver; mutation frequency using lambda cII transgenic medaka and lambda cII transgenic (Big Blue(R)) rats; and early morphological changes in the livers of both models using histopathology and immunohistochemistry. Pulse dose levels in fish were 0, 10, 25, 50, or 100 ppm DMN in the ambient water for 14 days. Since rats are reported to be especially sensitive to DMN, they received 0, 0.1, 1, 5, 10, or 25 ppm DMN in the drinking water for the same time period. While liver DNA adduct concentrations were similar in magnitude, mutant frequencies in the DMN-exposed medaka were up to 20 times higher than in the Big Blue rats. Future work with other compounds will generate a more complete picture of comparative dose response between different phyletic levels and will help guide risk assessors using "alternative" models.

  16. Equivalent Lung Dose and Systemic Exposure of Budesonide/Formoterol Combination via Easyhaler and Turbuhaler

    PubMed Central

    Sairanen, Ulla; Haikarainen, Jussi; Korhonen, Jani; Vahteristo, Mikko; Fuhr, Rainard; Kirjavainen, Merja

    2015-01-01

    Abstract Background: Easyhaler® device-metered dry powder inhaler containing budesonide and formoterol fumarate dihydrate (hereafter formoterol) for the treatment of asthma and chronic obstructive pulmonary disease has been developed. The current approvals of the product in Europe were based on several pharmacokinetic (PK) bioequivalence (BE) studies, and in vitro-in vivo correlation (IVIVC) modeling. Methods: Four PK studies were performed to compare the lung deposition and total systemic exposure of budesonide and formoterol after administration of budesonide/formoterol Easyhaler and the reference product, Symbicort Turbuhaler. The products were administered concomitantly with oral charcoal (lung deposition) and in two of the studies also without charcoal (total systemic exposure). Demonstration of BE for lung deposition (surrogate marker for efficacy) and non-inferiority for systemic exposure (surrogate marker for safety) were considered a proof of therapeutic equivalence. In addition, IVIVC models were constructed to predict study outcomes with different reference product fine particle doses (FPDs). Results: In the first pivotal study, the exposure and lung dose via Easyhaler were higher compared to the reference product (mean comparison estimates between 1.07 and 1.28) as the FPDs of the reference product batch were low. In the following studies, reference product batches with higher FPDs were utilized. In the second pivotal study, non-inferiority of Easyhaler compared to Turbuhaler was shown in safety and BE in efficacy for all other parameters except the formoterol AUCt. In the fourth study where two reference batches were compared to each other and Easyhaler, budesonide/formoterol Easyhaler was bioequivalent with one reference batch but not with the other having the highest FPDs amongst the 28 reference batches studied. In the IVIVC based study outcome predictions, the test product was bioequivalent with great proportion of the reference batches. For the

  17. MUTZ-3 derived Langerhans cells in human skin equivalents show differential migration and phenotypic plasticity after allergen or irritant exposure

    SciTech Connect

    Kosten, Ilona J.; Spiekstra, Sander W.; Gruijl, Tanja D. de; Gibbs, Susan

    2015-08-15

    After allergen or irritant exposure, Langerhans cells (LC) undergo phenotypic changes and exit the epidermis. In this study we describe the unique ability of MUTZ-3 derived Langerhans cells (MUTZ-LC) to display similar phenotypic plasticity as their primary counterparts when incorporated into a physiologically relevant full-thickness skin equivalent model (SE-LC). We describe differences and similarities in the mechanisms regulating LC migration and plasticity upon allergen or irritant exposure. The skin equivalent consisted of a reconstructed epidermis containing primary differentiated keratinocytes and CD1a{sup +} MUTZ-LC on a primary fibroblast-populated dermis. Skin equivalents were exposed to a panel of allergens and irritants. Topical exposure to sub-toxic concentrations of allergens (nickel sulfate, resorcinol, cinnamaldehyde) and irritants (Triton X-100, SDS, Tween 80) resulted in LC migration out of the epidermis and into the dermis. Neutralizing antibody to CXCL12 blocked allergen-induced migration, whereas anti-CCL5 blocked irritant-induced migration. In contrast to allergen exposure, irritant exposure resulted in cells within the dermis becoming CD1a{sup −}/CD14{sup +}/CD68{sup +} which is characteristic of a phenotypic switch of MUTZ-LC to a macrophage-like cell in the dermis. This phenotypic switch was blocked with anti-IL-10. Mechanisms previously identified as being involved in LC activation and migration in native human skin could thus be reproduced in the in vitro constructed skin equivalent model containing functional LC. This model therefore provides a unique and relevant research tool to study human LC biology in situ under controlled in vitro conditions, and will provide a powerful tool for hazard identification, testing novel therapeutics and identifying new drug targets. - Highlights: • MUTZ-3 derived Langerhans cells integrated into skin equivalents are fully functional. • Anti-CXCL12 blocks allergen-induced MUTZ-LC migration.

  18. 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.

  19. Measured Neutron Spectra and Dose Equivalents From a Mevion Single-Room, Passively Scattered Proton System Used for Craniospinal Irradiation.

    PubMed

    Howell, Rebecca M; Burgett, Eric A; Isaacs, Daniel; Price Hedrick, Samantha G; Reilly, Michael P; Rankine, Leith J; Grantham, Kevin K; Perkins, Stephanie; Klein, Eric E

    2016-05-01

    To measure, in the setting of typical passively scattered proton craniospinal irradiation (CSI) treatment, the secondary neutron spectra, and use these spectra to calculate dose equivalents for both internal and external neutrons delivered via a Mevion single-room compact proton system. Secondary neutron spectra were measured using extended-range Bonner spheres for whole brain, upper spine, and lower spine proton fields. The detector used can discriminate neutrons over the entire range of the energy spectrum encountered in proton therapy. To separately assess internally and externally generated neutrons, each of the fields was delivered with and without a phantom. Average neutron energy, total neutron fluence, and ambient dose equivalent [H* (10)] were calculated for each spectrum. Neutron dose equivalents as a function of depth were estimated by applying published neutron depth-dose data to in-air H* (10) values. For CSI fields, neutron spectra were similar, with a high-energy direct neutron peak, an evaporation peak, a thermal peak, and an intermediate continuum between the evaporation and thermal peaks. Neutrons in the evaporation peak made the largest contribution to dose equivalent. Internal neutrons had a very low to negligible contribution to dose equivalent compared with external neutrons, largely attributed to the measurement location being far outside the primary proton beam. Average energies ranged from 8.6 to 14.5 MeV, whereas fluences ranged from 6.91 × 10(6) to 1.04 × 10(7) n/cm(2)/Gy, and H* (10) ranged from 2.27 to 3.92 mSv/Gy. For CSI treatments delivered with a Mevion single-gantry proton therapy system, we found measured neutron dose was consistent with dose equivalents reported for CSI with other proton beamlines. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  20. 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 Hp(0.07) on a monthly basis, placing optically stimulated luminescence dosimeters (OSLDs) on goggles. The Hp(0.07) personal dose equivalent was measured over aprons with whole-body OSLDs. Data on patient dose as recorded by the kerma-area product (PKA) 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 PKA 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.

  1. Improvement Accuracy of Assessment of Total Equivalent Dose Rate during Air Travel

    NASA Astrophysics Data System (ADS)

    Dorenskiy, Sergey; Minligareev, Vladimir

    For radiation safety on the classic flight altitudes 8-11 km is necessary to develop a methodology for calculating the total equivalent dose rate (EDR) to prevent excess exposure of passengers and crews of airliners. During development it became necessary to assess all components affecting the calculation of EDR Comprehensive analysis of the solution to this problem, based on the developed program basis, allowing to automate calculations , as well as on the assessment of the statistical data is introduced. The results have shown that: 1) Limiting accuracy of error of geomagnetic cutoff rigidity (GCR) in the period from 2005 to 2010 was 5% This error is not significant within the considered problems. 2) It is necessary to take into account seasonal variations of atmospheric parameters in the calculation of the EDR. The difference in the determination of dose rate can reach 31% Diurnal variations of atmospheric parameters are offered to consider to improve reliability of EDR estimates. 3) Introduction in the GCR calculations of additional parameters is necessary for reliability improvement and estimation accuracy of EDR on flight routs (Kp index of geomagnetic activity , etc.).

  2. Depth-dose equivalent relationship for cosmic rays at various solar minima

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Cucinotta, F. A.; O'Neill, P. M.

    1993-01-01

    Galactic cosmic rays (GCR) pose a serious radiation hazard for long-duration missions. In designing a lunar habitat or a Mars transfer vehicle, the radiation exposure determines the GCR shielding thickness, and hence the weight of spacecraft. Using the spherically symmetric diffusion theory of the solar modulation of GCR, and data on the differential energy spectra of H, He, O, and Fe, from 1965 to 1989, it has been shown that (1) the flux is determined by the diffusion parameter which is a function of the time in the solar cycle, and (2) the fluxes in the 1954 and 1976-1977 solar minima were similar and higher than those in 1965. In this paper, we have extended the spherical solar modulation theory back to 1954. The 1954-1955 GCR flux was nearly the same as that from 1976 to 1977; the 1965 flux values were nearly the same as those in 1986. Using this theory we have obtained the GCR spectra for all the nuclei, and calculated the depth dose as a function of Al thickness. It is shown that the shielding required to stay below 0.5 Sv is 17.5 -3/+8 g/sq cm of Al, and 9 -1.5/+5 g/sq cm to stay below 0.6 Sv. The calculated dose equivalent using the ICRP 60 values for quality factors is about 15 percent higher than that calculated using the ICRP 26 value.

  3. In vivo evaluating skin doses for lung cancer patients undergoing volumetric modulated arc therapy treatment.

    PubMed

    Tseng, Hsien-Chun; Pan, Lung-Kang; Chen, Hsin-Yu; Liu, Wen-Shan; Hsu, Chang-Chieh; Chen, Chien-Yi

    2015-01-01

    This study is the first to use 10- to 90-kg tissue-equivalent phantoms as patient surrogates to measure peripheral skin doses (Dskin) in lung cancer treatment through Volumetric Modulated Arc Therapy of the Axesse linac. Five tissue-equivalent and Rando phantoms were used to simulate lung cancer patients using the thermoluminescent dosimetry (TLD-100H) approach. TLD-100H was calibrated using 6 MV photons coming from the Axesse linac. Then it was inserted into phantom positions that closely corresponded with the position of the represented organs and tissues. TLDs were measured using the Harshaw 3500 TLD reader. The ICRP 60 evaluated the mean Dskin to the lung cancer for 1 fraction (7 Gy) undergoing VMAT. The Dskin of these phantoms ranged from 0.51±0.08 (10-kg) to 0.22±0.03 (90-kg) mSv/Gy. Each experiment examined the relationship between the Dskin and the distance from the treatment field. These revealed strong variations in positions close to the tumor center. The correlation between Dskin and body weight was Dskin (mSv) = -0.0034x + 0.5296, where x was phantom's weight in kg. R2 is equal to 0.9788. This equation can be used to derive an equation for lung cancer in males. Finally, the results are compared to other published research. These findings are pertinent to patients, physicians, radiologists, and the public.

  4. Monte Carlo study of neutron-ambient dose equivalent to patient in treatment room.

    PubMed

    Mohammadi, A; Afarideh, H; Abbasi Davani, F; Ghergherehchi, M; Arbabi, A

    2016-12-01

    This paper presents an analytical method for the calculation of the neutron ambient dose equivalent H* (10) regarding patients, whereby the different concrete types that are used in the surrounding walls of the treatment room are considered. This work has been performed according to a detailed simulation of the Varian 2300C/D linear accelerator head that is operated at 18MV, and silver activation counter as a neutron detector, for which the Monte Carlo MCNPX 2.6 code is used, with and without the treatment room walls. The results show that, when compared to the neutrons that leak from the LINAC, both the scattered and thermal neutrons are the major factors that comprise the out-of field neutron dose. The scattering factors for the limonite-steel, magnetite-steel, and ordinary concretes have been calculated as 0.91±0.09, 1.08±0.10, and 0.371±0.01, respectively, while the corresponding thermal factors are 34.22±3.84, 23.44±1.62, and 52.28±1.99, respectively (both the scattering and thermal factors are for the isocenter region); moreover, the treatment room is composed of magnetite-steel and limonite-steel concretes, so the neutron doses to the patient are 1.79 times and 1.62 times greater than that from an ordinary concrete composition. The results also confirm that the scattering and thermal factors do not depend on the details of the chosen linear accelerator head model. It is anticipated that the results of the present work will be of great interest to the manufacturers of medical linear accelerators.

  5. A new water absorbable mechanical Epidermal skin equivalent: the combination of hydrophobic PDMS and hydrophilic PVA hydrogel.

    PubMed

    Morales-Hurtado, M; Zeng, X; Gonzalez-Rodriguez, P; Ten Elshof, J E; van der Heide, E

    2015-06-01

    Research on human skin interactions with healthcare and lifestyle products is a topic continuously attracting scientific studies over the past years. It is possible to evaluate skin mechanical properties based on human or animal experimentation, yet in addition to possible ethical issues, these samples are hard to obtain, expensive and give rise to highly variable results. Therefore, the design of a skin equivalent is essential. This paper describes the design and characterization of a new Epidermal Skin Equivalent (ESE). The material resembles the properties of epidermis and is a first approach to mimic the mechanical properties of the human skin structure, variable with the length scale. The ESE is based on a mixture of Polydimethyl Siloxane (PDMS) and Polyvinyl Alcohol (PVA) hydrogel cross-linked with Glutaraldehyde (GA). It was chemically characterized by XPS and FTIR measurements and its cross section was observed by macroscopy and cryoSEM. Confocal Microscope analysis on the surface of the ESE showed an arithmetic roughness (Ra) between 14-16 μm and contact angle (CA) values between 50-60°, both of which are close to the values of in vivo human skins reported in the literature. The Equilibrium Water Content (ECW) was around 33.8% and Thermo Gravimetric Analysis (TGA) confirmed the composition of the ESE samples. Moreover, the mechanical performance was determined by indentation tests and Dynamo Thermo Mechanical Analysis (DTMA) shear measurements. The indentation results were in good agreement with that of the target epidermis reported in the literature with an elastic modulus between 0.1-1.5 MPa and it showed dependency on the water content. According to the DTMA measurements, the ESE exhibits a viscoelastic behavior, with a shear modulus between 1-2.5MPa variable with temperature, frequency and the hydration of the samples.

  6. Monte Carlo skin dose simulation in intraoperative radiotherapy of breast cancer using spherical applicators

    NASA Astrophysics Data System (ADS)

    Moradi, F.; Ung, N. M.; Khandaker, M. U.; Mahdiraji, G. A.; Saad, M.; Malik, R. Abdul; Bustam, A. Z.; Zaili, Z.; Bradley, D. A.

    2017-08-01

    The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators. Highlights: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin

  7. Skin and gonadal dose reduction during hip radiography of the bull.

    PubMed

    Wood, A K; Blockey, B; Reynolds, K M; Leith, I S; Burns, P A

    1979-10-01

    Radiology is being used to an increasing extent in the clinical diagnosis of hip lameness in bulls. Consequent gonadal doses may have important implications in later breeding programmes. Skin and gonadal doses were recorded during hip radiography of 18 bulls. An additional 0.13 mm copper filtration reduced skin dose by more than one third, but had no effect on gonadal dose. The average radiation dose to the gonads was approximately halved by completely surrounding the scrotum with lead sheeting 0.95 mm in thickness.

  8. Differential innate immune responses of a living skin equivalent model colonized by Staphylococcus epidermidis or Staphylococcus aureus.

    PubMed

    Holland, Diana B; Bojar, Richard A; Farrar, Mark D; Holland, Keith T

    2009-01-01

    Staphylococcus epidermidis is a commensal on skin, whereas Staphylococcus aureus is a transient pathogen. The aim was to determine whether the skin's innate defence systems responded differently to these microorganisms. Differential gene expression of a human skin equivalent (SE) model was assessed by microarray technology, in response to colonization by S. epidermidis or S. aureus. Only a small number of transcripts were significantly (P<0.0001) increased (12) or decreased (35) with gene expression changes of >2-fold on SEs colonized with S. epidermidis compared with controls (no colonization). Expression of one innate defence gene, pentraxin 3 (PTX3), was upregulated, while psoriasin, S100A12, S100A15, beta defensin 4, beta defensin 3, lipocalin 2 and peptidoglycan recognition protein 2 were downregulated. In contrast, large numbers of transcripts were significantly increased (480) or decreased (397) with gene expression changes of >2-fold on SEs colonized with S. aureus compared with controls. There was upregulation in gene expression of many skin defence factors including Toll-like receptor 2, beta defensin 4, properdin, PTX3, proinflammatory cytokines tumour necrosis factor-alpha, IL-1 alpha, IL-1 beta, IL-17C, IL-20, IL-23A and chemokines IL-8, CCL4, CCL5, CCL20 and CCL27. These differences may partly explain why S. epidermidis is a normal skin resident and S. aureus is not.

  9. Calculating the peak skin dose resulting from fluoroscopically guided interventions. Part I: Methods.

    PubMed

    Jones, A Kyle; Pasciak, Alexander S

    2011-11-15

    While direct measurement of the peak skin dose resulting from a fluoroscopically-guided procedure is possible, the decision must be made a priori at additional cost and time. It is most often the case that the need for accurate knowledge of the peak skin dose is realized only after a procedure has been completed, or after a suspected reaction has been discovered. Part I of this review article discusses methods for calculating the peak skin dose across a range of clinical scenarios. In some cases, a wealth of data are available, while in other cases few data are available and additional data must be measured in order to estimate the peak skin dose. Data may be gathered from a dose report, the DICOM headers of images, or from staff and physician interviews. After data are gathered, specific steps must be followed to convert dose metrics, such as the reference point air kerma (K(a,r)) or the kerma area product (KAP), into peak skin dose. These steps require knowledge of other related factors, such as the f-factor and the backscatter factor, tables of which are provided in this manuscript. Sources of error and the impact of these errors on the accuracy of the final estimate of the peak skin dose are discussed.

  10. Technical advance: Langerhans cells derived from a human cell line in a full-thickness skin equivalent undergo allergen-induced maturation and migration.

    PubMed

    Ouwehand, Krista; Spiekstra, Sander W; Waaijman, Taco; Scheper, Rik J; de Gruijl, Tanja D; Gibbs, Susan

    2011-11-01

    In this report, the construction of a functional, immunocompetent, full-thickness skin equivalent (SE) is described, consisting of an epidermal compartment containing keratinocytes, melanocytes, and human LCs derived from the MUTZ-3 cell line (MUTZ-LC) and a fibroblast-populated dermal compartment. The CD1a(+)Langerin(+)HLA-DR(+) MUTZ-LCs populate the entire epidermis at a similar density to that found in native skin. Exposure of the SE to subtoxic concentrations of the allergens NiSO(4) and resorcinol resulted in LC migration out of the epidermis toward the fibroblast-populated dermal compartment. A significant dose-dependent up-regulation of the DC maturation-related CCR7 and IL-1β transcripts and of CD83 at the protein level upon epidermal exposure to both allergens was observed, indicative of maturation and migration of the epidermally incorporated LC. We have thus successfully developed a reproducible and functional full-thickness SE model containing epidermal MUTZ-LC. This model offers an alternative to animal testing for identifying potential chemical sensitizers and for skin-based vaccination strategies and provides a unique research tool to study human LC biology in situ under controlled in vitro conditions.

  11. Relevance of Biologically Equivalent Dose Values in Outcome Evaluation of Stereotactic Radiotherapy for Lung Nodules

    SciTech Connect

    Casamassima, Franco Masi, Laura; Bonucci, Ivano; Polli, Caterina; Menichelli, Claudia; Gulisano, Massimo; Pacini, Stefania; Aterini, Stefano; Cavedon, Carlo

    2008-05-01

    Purpose: Different biologically equivalent dose (BED) values associated with stereotactic radiotherapy (SRT) of patients with primary and metastatic pulmonary nodules were studied. The BED values were calculated for tumoral tissue and low {alpha}/{beta} ratio, assuming that better local response could be obtained by using stereotactic high-BED treatment. Methods and Materials: Fifty-eight patients with T1-T3 N0 non-small-cell lung cancer and 46 patients with metastatic lung nodules were treated with SRT. The BED was calculated for {alpha}/{beta} ratios of 3 and 10. Overall survival (OS) was assessed according to Kaplan-Meier and appraised as a function of three BED levels: low (30-50 Gy), medium (50-70 Gy), and high (70-98 Gy; {alpha}/{beta} = 10). Results: The OS rates for all 104 patients at 12, 24, and 36 months were 73%, 48.3%, and 35.8%, respectively. Local response greater than 50% for low, medium, and high BED values was observed in 54%, 47%, and 73%, respectively. In the high-BED treated group, OS rates at 12, 24, and 36 months (80.9%, 70%, and 53.6%, respectively) were significantly improved compared with low- (69%, 46.1%, and 30.7%, respectively) and medium-BED (67%, 28%, and 21%, respectively) treated patients. Results are also discussed in terms of BED calculated on {alpha}/{beta} 3 Gy characteristic of the microcapillary bed. No acute toxicity higher than Grade 1 was observed. Conclusions: Radioablation of pulmonary neoplastic nodules may be achieved with SRT delivered by using a high-dose fraction with high BED value.

  12. Evaluation of HIFU-induced lesion region using temperature threshold and equivalent thermal dose methods

    NASA Astrophysics Data System (ADS)

    Chang, Shihui; Xue, Fanfan; Zhou, Wenzheng; Zhang, Ji; Jian, Xiqi

    2017-03-01

    Usually, numerical simulation is used to predict the acoustic filed and temperature distribution of high intensity focused ultrasound (HIFU). In this paper, the simulated lesion volumes obtained by temperature threshold (TRT) 60 °C and equivalent thermal dose (ETD) 240 min were compared with the experimental results which were obtained by animal tissue experiment in vitro. In the simulation, the calculated model was established according to the vitro tissue experiment, and the Finite Difference Time Domain (FDTD) method was used to calculate the acoustic field and temperature distribution in bovine liver by the Westervelt formula and Pennes bio-heat transfer equation, and the non-linear characteristics of the ultrasound was considered. In the experiment, the fresh bovine liver was exposed for 8s, 10s, 12s under different power conditions (150W, 170W, 190W, 210W), and the exposure was repeated 6 times under the same dose. After the exposures, the liver was sliced and photographed every 0.2mm, and the area of the lesion region in every photo was calculated. Then, every value of the areas was multiplied by 0.2mm, and summed to get the approximation volume of the lesion region. The comparison result shows that the lesion volume of the region calculated by TRT 60 °C in simulation was much closer to the lesion volume obtained in experiment, and the volume of the region above 60 °C was larger than the experimental results, but the volume deviation was not exceed 10%. The volume of the lesion region calculated by ETD 240 min was larger than that calculated by TRT 60 °C in simulation, and the volume deviations were ranged from 4.9% to 23.7%.

  13. 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

  14. Estimation of ambient dose equivalent distribution in the (18)F-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 %.

  15. An Evaluation of Dose Equivalence between Synchrotron Microbeam Radiation Therapy and Conventional Broadbeam Radiation Using Clonogenic and Cell Impedance Assays

    PubMed Central

    Ibahim, Mohammad Johari; Crosbie, Jeffrey C.; Yang, Yuqing; Zaitseva, Marina; Stevenson, Andrew W.; Rogers, Peter A. W.; Paiva, Premila

    2014-01-01

    Background High-dose synchrotron microbeam radiation therapy (MRT) has shown the potential to deliver improved outcomes over conventional broadbeam (BB) radiation therapy. To implement synchrotron MRT clinically for cancer treatment, it is necessary to undertake dose equivalence studies to identify MRT doses that give similar outcomes to BB treatments. Aim To develop an in vitro approach to determine biological dose equivalence between MRT and BB using two different cell-based assays. Methods The acute response of tumour and normal cell lines (EMT6.5, 4T1.2, NMuMG, EMT6.5ch, 4T1ch5, SaOS-2) to MRT (50–560 Gy) and BB (1.5–10 Gy) irradiation was investigated using clonogenic and real time cell impedance sensing (RT-CIS)/xCELLigence assays. MRT was performed using a lattice of 25 or 50 µm-wide planar, polychromatic kilovoltage X-ray microbeams with 200 µm peak separation. BB irradiations were performed using a Co60 teletherapy unit or a synchrotron radiation source. BB doses that would generate biological responses similar to MRT were calculated by data interpolation and verified by clonogenic and RT-CIS assays. Results For a given cell line, MRT equivalent BB doses identified by RT-CIS/xCELLigence were similar to those identified by clonogenic assays. Dose equivalence between MRT and BB were verified in vitro in two cell lines; EMT6.5ch and SaOS-2 by clonogenic assays and RT-CIS/xCELLigence. We found for example, that BB doses of 3.4±0.1 Gy and 4.40±0.04 Gy were radiobiologically equivalent to a peak, microbeam dose of 112 Gy using clonogenic and RT-CIS assays respectively on EMT6.5ch cells. Conclusion Our data provides the first determination of biological dose equivalence between BB and MRT modalities for different cell lines and identifies RT-CIS/xCELLigence assays as a suitable substitute for clonogenic assays. These results will be useful for the safe selection of MRT doses for future veterinary and clinical trials. PMID:24945301

  16. Evaluation of a human bio-engineered skin equivalent for drug permeation studies.

    PubMed

    Asbill, C; Kim, N; El-Kattan, A; Creek, K; Wertz, P; Michniak, B

    2000-09-01

    To test the barrier function of a bio-engineered human skin (BHS) using three model drugs (caffeine, hydrocortisone, and tamoxifen) in vitro. To investigate the lipid composition and microscopic structure of the BHS. The human skin substitute was composed of both epidermal and dermal layers, the latter having a bovine collagen matrix. The permeability of the BHS to three model drugs was compared to that obtained in other percutaneous testing models (human cadaver skin, hairless mouse skin, and EpiDerm). Lipid analysis of the BHS was performed by high performance thin layered chromatography. Histological evaluation of the BHS was performed using routine H&E staining. The BHS mimicked human skin in terms of lipid composition, gross ultrastructure, and the formation of a stratum corneum. However, the permeability of the BHS to caffeine, hydrocortisone, and tamoxifen was 3-4 fold higher than that of human cadaver skin. In summary, the results indicate that the BHS may be an acceptable in vitro model for drug permeability testing.

  17. 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.

  18. MALDI MSI analysis of lipid changes in living skin equivalents in response to emollient creams containing palmitoylethanolamide.

    PubMed

    Mitchell, Christopher A; Donaldson, Michael; Francese, Simona; Clench, Malcolm R

    2016-07-15

    Mass spectrometry imaging (MSI) is a powerful tool for the study of intact tissue sections. The use of matrix-assisted laser desorption/ionisation (MALDI) MSI for the study of the distribution and effect of emollient treatment on sections of reconstructed living skin equivalents during their development and maturation is described. Living skin equivalent (LSE) samples were obtained at 14days development, re-suspended in maintenance medium and incubated for 24h after delivery. The medium was changed, the LSE treated with either Physiogel A.I.® or Oilatum Junior® emollients and then re-incubated and samples taken at 4, 6 and 24h time points. Mass spectra and mass spectral images were recorded from 12μm sections of the LSE taken at each time point for comparison using MALDI mass spectrometry (MS). It was possible to detect ions characteristic of each emollient in the LSE. In addition a number of lipid species previously reported as being significant in the maturation of the LSE were observable. At the 24h time point, the images revealed what appeared to be differences in the organisation of the skin cells observed across the Physiogel A.I.® treatment group tissue sections when directly compared to the untreated tissue group. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. TGF-β1 induces differentiation of papillary fibroblasts to reticular fibroblasts in monolayer culture but not in human skin equivalents.

    PubMed

    Janson, David; Saintigny, Gaëlle; Zeypveld, Jeroen; Mahé, Christian; El Ghalbzouri, Abdoelwaheb

    2014-01-01

    Fibroblasts isolated from the papillary and reticular dermis are different from each other in vitro. If papillary fibroblasts are subjected to prolonged serial passaging they will differentiate into reticular fibroblasts. Reticular fibroblasts have been shown to resemble myofibroblasts in several ways. TGF-β1 is the most important factor involved in myofibroblast differentiation. we investigated if TGF-β1 can induce differentiation of papillary fibroblasts into reticular fibroblasts, in monolayer cultures and in human skin equivalents. Monolayer cultures of and human skin equivalents generated with papillary fibroblasts were stimulated with TGF-β1. The expression of markers specific for reticular and papillary fibroblasts was measured by qPCR and immunohistochemical analysis in monolayer cultures. In human skin equivalents, the morphology and the expression of several markers was analysed and compared to untreated papillary and reticular human skin equivalents. Monolayer cultures of papillary fibroblasts started to express a reticular marker profile after stimulation with TGF-β1. Human skin equivalents generated with papillary fibroblast and stimulated with TGF-β1 were similar to papillary control equivalents and did not obtain reticular characteristics. Expression of reticular markers was only found in the lower layers of TGF-β1-stimulated papillary skin equivalents. TGF-β1 can induce differentiation to reticular fibroblasts in monolayer cultures of papillary fibroblasts. In skin equivalents no such effects were found. The major difference between these experiments is the presence of extracellular matrix in skin equivalents. Therefore, we hypothesize that the matrix secreted by papillary fibroblasts protects them from TGF-β1 induced differentiation.

  20. 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).

  1. Monte Carlo simulation of the neutron spectral fluence and dose equivalent for use in shielding a proton therapy vault.

    PubMed

    Zheng, Yuanshui; Newhauser, Wayne; Klein, Eric; Low, Daniel

    2009-11-21

    Neutron production is of principal concern when designing proton therapy vault shielding. Conventionally, neutron calculations are based on analytical methods, which do not accurately consider beam shaping components and nozzle shielding. The goal of this study was to calculate, using Monte Carlo modeling, the neutron spectral fluence and neutron dose equivalent generated by a realistic proton therapy nozzle and evaluate how these data could be used in shielding calculations. We modeled a contemporary passive scattering proton therapy nozzle in detail with the MCNPX simulation code. The neutron spectral fluence and dose equivalent at various locations in the treatment room were calculated and compared to those obtained from a thick iron target bombarded by parallel proton beams, the simplified geometry on which analytical methods are based. The neutron spectral fluence distributions were similar for both methods, with deeply penetrating high-energy neutrons (E > 10 MeV) being most prevalent along the beam central axis, and low-energy neutrons predominating the neutron spectral fluence in the lateral region. However, unlike the inverse square falloff used in conventional analytical methods, this study shows that the neutron dose equivalent per therapeutic dose in the treatment room decreased with distance approximately following a power law, with an exponent of about -1.63 in the lateral region and -1.73 in the downstream region. Based on the simulated data according to the detailed nozzle modeling, we developed an empirical equation to estimate the neutron dose equivalent at any location and distance in the treatment vault, e.g. for cases in which detailed Monte Carlo modeling is not feasible. We applied the simulated neutron spectral fluence and dose equivalent to a shielding calculation as an example.

  2. Monte Carlo simulation of the neutron spectral fluence and dose equivalent for use in shielding a proton therapy vault

    PubMed Central

    Zheng, Yuanshui; Newhauser, Wayne; Klein, Eric; Low, Daniel

    2014-01-01

    Neutron production is of principal concern when designing proton therapy vault shielding. Conventionally, neutron calculations are based on analytical methods, which do not accurately consider beam shaping components and nozzle shielding. The goal of this study was to calculate, using Monte Carlo modeling, the neutron spectral fluence and neutron dose equivalent generated by a realistic proton therapy nozzle and evaluate how these data could be used in shielding calculations. We modeled a contemporary passive scattering proton therapy nozzle in detail with the MCNPX simulation code. The neutron spectral fluence and dose equivalent at various locations in the treatment room were calculated and compared to those obtained from a thick iron target bombarded by parallel proton beams, the simplified geometry on which analytical methods are based. The neutron spectral fluence distributions were similar for both methods, with deeply penetrating high-energy neutrons (E > 10 MeV) being most prevalent along the beam central axis, and low-energy neutrons predominating the neutron spectral fluence in the lateral region. However, unlike the inverse square falloff used in conventional analytical methods, this study shows that the neutron dose equivalent per therapeutic dose in the treatment room decreased with distance approximately following a power law, with an exponent of about −1.63 in the lateral region and −1.73 in the downstream region. Based on the simulated data according to the detailed nozzle modeling, we developed an empirical equation to estimate the neutron dose equivalent at any location and distance in the treatment vault, e.g. for cases in which detailed Monte Carlo modeling is not feasible. We applied the simulated neutron spectral fluence and dose equivalent to a shielding calculation as an example. PMID:19887713

  3. Monte Carlo simulation of the neutron spectral fluence and dose equivalent for use in shielding a proton therapy vault

    NASA Astrophysics Data System (ADS)

    Zheng, Yuanshui; Newhauser, Wayne; Klein, Eric; Low, Daniel

    2009-11-01

    Neutron production is of principal concern when designing proton therapy vault shielding. Conventionally, neutron calculations are based on analytical methods, which do not accurately consider beam shaping components and nozzle shielding. The goal of this study was to calculate, using Monte Carlo modeling, the neutron spectral fluence and neutron dose equivalent generated by a realistic proton therapy nozzle and evaluate how these data could be used in shielding calculations. We modeled a contemporary passive scattering proton therapy nozzle in detail with the MCNPX simulation code. The neutron spectral fluence and dose equivalent at various locations in the treatment room were calculated and compared to those obtained from a thick iron target bombarded by parallel proton beams, the simplified geometry on which analytical methods are based. The neutron spectral fluence distributions were similar for both methods, with deeply penetrating high-energy neutrons (E > 10 MeV) being most prevalent along the beam central axis, and low-energy neutrons predominating the neutron spectral fluence in the lateral region. However, unlike the inverse square falloff used in conventional analytical methods, this study shows that the neutron dose equivalent per therapeutic dose in the treatment room decreased with distance approximately following a power law, with an exponent of about -1.63 in the lateral region and -1.73 in the downstream region. Based on the simulated data according to the detailed nozzle modeling, we developed an empirical equation to estimate the neutron dose equivalent at any location and distance in the treatment vault, e.g. for cases in which detailed Monte Carlo modeling is not feasible. We applied the simulated neutron spectral fluence and dose equivalent to a shielding calculation as an example.

  4. SU-E-T-567: Neutron Dose Equivalent Evaluation for Pencil Beam Scanning Proton Therapy with Apertures

    SciTech Connect

    Geng, C; Schuemann, J; Moteabbed, M; Paganetti, H

    2015-06-15

    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 equivalent 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)

  5. 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.

  6. Replacement of animal-derived collagen matrix by human fibroblast-derived dermal matrix for human skin equivalent products.

    PubMed

    El Ghalbzouri, Abdoelwaheb; Commandeur, Suzan; Rietveld, Marion H; Mulder, Aat A; Willemze, Rein

    2009-01-01

    Reconstructed human skin equivalents (HSEs) are representative models of human skin and widely used for research purposes and clinical applications. Traditional methods to generate HSEs are based on the seeding of human keratinocytes onto three-dimensional human fibroblast-populated non-human collagen matrices. Current HSEs have a limited lifespan of approximately 8 weeks, rendering them unsuitable for long-term studies. Here we present a new generation of HSEs being fully composed of human components and which can be cultured up to 20 weeks. This model is generated on a primary human fibroblast-derived dermal matrix. Pro-collagen type I secretion by human fibroblasts stabilized during long-term culture, providing a continuous and functional human dermal matrix. In contrast to rat-tail collagen-based HSEs, the present fibroblast-derived matrix-based HSEs contain more continuity in the number of viable cell layers in long-term cultures. In addition, these new skin models exhibit normal differentiation and proliferation, based on expression of K10/K15, and K16/K17, respectively. Detection of collagen types IV and VII and laminin 332 was confined to the epidermal-dermal junction, as in native skin. The presence of hemidesmosomes and anchoring fibrils was demonstrated by electron microscopy. Finally, we show that the presented HSE contained a higher concentration of the normal moisturizing factor compared to rat-tail collagen-based skin models, providing a further representation of functional normal human skin in vitro. This study, therefore, demonstrates the role of the dermal microenvironment on epidermal regeneration and lifespan in vitro.

  7. Measurements of radioactivity in Jamaican building materials and gamma dose equivalents in a prototype red mud house

    SciTech Connect

    Pinnock, W.R. )

    1991-11-01

    Concentrations of 226Ra, 232Th, and 40K measured in bauxite waste, local building materials, and soils are presented and used in model equations to estimate the effective gamma dose-equivalent increments over background in the center of a standard-sized room in a prototype house. Calculated and measured values compare reasonably well.

  8. Ambient dose equivalent rate in Goiânia 12 years after the 137Cs radiological accident.

    PubMed

    Yoshimura, E M; Umisedo, N K; Facure, A; Anjos, R M; Okuno, E

    2001-06-01

    This paper describes the situation of ambient dose equivalent rates in four of the main foci of 137Cs contamination in the city of Goiânia, Brazil, in 1999, 12 y after one of the worst radiological accidents in the world. During the decontamination, all the buildings of the three highly contaminated sites were demolished and the top soil removed. Afterwards, the soil of two of these lots was covered with concrete, and they remain vacant today. The soil of the third of these lots, identified here as E, previously known as junkyard II, was covered only with clean soil. Three to four years after the accident, new houses were constructed on this lot, and some very poor people live and work there collecting recyclable material. Gamma ray spectrometry, with a portable survey meter, was performed in the quoted places along with outdoor measurements in many other locations of Goiânia. The average ambient dose equivalent rate due to natural background radiation from radionuclides in the soil and cosmic radiation in non-contaminated areas of the city of Goiânia is 62 nSv h(-1). In most of the highly contaminated sites during the accident, the average ambient dose equivalent rate ranged from around 100 to 1,000 nSv h(-1). The only exception was site E, where values of ambient dose equivalent rate as high as 2.6 microSv h(-1) were found.

  9. Association Between Maximal Skin Dose and Breast Brachytherapy Outcome: A Proposal for More Rigorous Dosimetric Constraints

    SciTech Connect

    Cuttino, Laurie W.; Heffernan, Jill; Vera, Robyn; Rosu, Mihaela; Ramakrishnan, V. Ramesh; Arthur, Douglas W.

    2011-11-01

    Purpose: Multiple investigations have used the skin distance as a surrogate for the skin dose and have shown that distances <6 mm have been associated with late toxicity after MammoSite brachytherapy. No publications have yet described the relationship between the actual maximal skin dose and the outcome. The present study analyzed the maximal skin dose delivered and the occurrence of late toxicity in a large cohort of patients with prolonged follow-up. Methods: A total of 96 patients treated with breast brachytherapy between 2000 and 2007 for whom complete planning and follow-up data were available were included in the present analysis. The median follow-up was 48 months (range, 24-111). Of the 96 patients, 40 were treated with multicatheter interstitial brachytherapy and 56 with MammoSite. A multivariate statistical analysis was performed to determine the relationship between several dosimetric parameters and patient outcome. Results: The treatment was well tolerated, with 98% of patients experiencing good to excellent cosmesis. Significant late toxicity was uncommon. The maximal dose delivered to the skin was significantly associated with the incidence of any degree of telangiectasia (p = .009) and moderate to severe fibrosis (p = .010). The incidence of late toxicity was significantly increased when the dose to the skin was >4.05 Gy/fraction. Conclusion: The initial skin dose recommendations have been based on safe use and the avoidance of significant toxicity. The results from the present study have suggested that patients might further benefit if more rigorous constraints were applied and if the skin dose were limited to 120% of the prescription dose.

  10. A system to track skin dose for neuro-interventional cone-beam computed tomography (CBCT)

    NASA Astrophysics Data System (ADS)

    Vijayan, Sarath; Xiong, Zhenyu; Rudin, Stephen; Bednarek, Daniel R.

    2016-03-01

    The skin-dose tracking system (DTS) provides a color-coded illustration of the cumulative skin-dose distribution on a closely-matching 3D graphic of the patient during fluoroscopic interventions in real-time for immediate feedback to the interventionist. The skin-dose tracking utility of DTS has been extended to include cone-beam computed tomography (CBCT) of neurointerventions. While the DTS was developed to track the entrance skin dose including backscatter, a significant part of the dose in CBCT is contributed by exit primary radiation and scatter due to the many overlapping projections during the rotational scan. The variation of backscatter inside and outside the collimated beam was measured with radiochromic film and a curve was fit to obtain a scatter spread function that could be applied in the DTS. Likewise, the exit dose distribution was measured with radiochromic film for a single projection and a correction factor was determined as a function of path length through the head. Both of these sources of skin dose are added for every projection in the CBCT scan to obtain a total dose mapping over the patient graphic. Results show the backscatter to follow a sigmoidal falloff near the edge of the beam, extending outside the beam as far as 8 cm. The exit dose measured for a cylindrical CTDI phantom was nearly 10 % of the entrance peak skin dose for the central ray. The dose mapping performed by the DTS for a CBCT scan was compared to that measured with radiochromic film and a CTDI-head phantom with good agreement.

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

    PubMed

    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 133Xe 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 133Xe. Material samples were placed at selected distances from the detector phantom, both individually and in various combinations. 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.

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

    SciTech Connect

    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. 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.

  13. Comparison of equivalent doses of fentanyl buccal tablets and arteriovenous differences in fentanyl pharmacokinetics.

    PubMed

    Darwish, Mona; Kirby, Mary; Robertson, Philmore; Hellriegel, Edward; Jiang, John G

    2006-01-01

    The fentanyl buccal tablet (FBT) is designed to enhance the rate and extent of fentanyl absorption through the buccal mucosa. To evaluate the bioequivalence of microg-equivalent doses of FBT administered as single and multiple tablets and assess differences in the arterial and venous pharmacokinetics of FBT in healthy volunteers. Twenty-seven healthy adults, aged 19-45 years, participated in the randomised, open-label, three-period, crossover study. In the first two periods, FBT was administered as four 100 microg tablets simultaneously or one FBT 400 microg to assess bioequivalence. Venous blood samples were obtained over a 72-hour period to measure plasma fentanyl concentrations. In the third period, arterial and venous blood samples were obtained simultaneously from before administration of one FBT 400 microg through 4 hours after administration to evaluate the impact of arterial versus venous sampling on the pharmacokinetic profile. As subjects were not opioid tolerant, naltrexone was administered to block opioid receptor-mediated effects of fentanyl. Adverse events were recorded throughout. Maximum plasma concentration (C(max)) and area under the plasma concentration-time curve from time zero to infinity (AUC(infinity)) on average were approximately 12% and 13% higher, respectively, for FBT administered as four 100 microg tablets simultaneously compared with one FBT 400 microg. Maximum plasma concentrations in the arterial circulation were approximately 60% higher and occurred 15 minutes earlier than those measured from the venous circulation. No serious adverse events were reported during the study. Despite small differences in C(max) and AUC(infinity) (on average 12% and 13%, respectively), FBT administered as four 100 microg tablets simultaneously compared with one 400 microg tablet did not meet the criteria for bioequivalence. An increased surface area exposure with four tablets compared with one tablet may account for the slightly higher maximum

  14. 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.

  15. 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.

  16. Neutron dose equivalent and neutron spectra in tissue for clinical linacs operating at 15, 18 and 20 MV.

    PubMed

    Martínez-Ovalle, S A; Barquero, R; Gómez-Ros, J M; Lallena, A M

    2011-11-01

    In this work, the dose equivalent due to photoneutrons and the neutron spectra in tissue was calculated for various linacs (Varian Clinac 2100C, Elekta Inor, Elekta SL25 and Siemens Mevatron KDS) operating at energies between 15 and 20 MV, using the Monte Carlo code MCNPX (v. 2.5). The dose equivalent in an ICRU tissue phantom has been calculated for anteroposterior treatments with a detailed simulation of the geometry of the linac head and the coupled electron-photon-neutron transport. Neutron spectra at the phantom entrance and at 1-cm depth in the phantom, depth distribution of the neutron fluence in the beam axis and dose distributions outside the beam axis at various depths have also been calculated and compared with previously published results. The differences between the neutron production of the various linacs considered has been analysed. Varian linacs show a larger neutron production than the Elekta and Siemens linacs at the same operating energy. The dose equivalent due to neutrons produced by medical linacs operating at energies >15 MeV is relevant and should not be neglected because of the additional doses that patients can receive.

  17. Intercomparison 2013 on measurements of the personal dose equivalent Hp(10) in photon fields in the African region.

    PubMed

    Arib, M; Herrati, A; Dari, F; Ma, J; Lounis-Mokrani, Z

    2015-02-01

    An intercomparison exercise on the measurement of personal dose equivalent Hp(10) was jointly organised by the International Atomic Energy Agency and the Nuclear Research Centre of Algiers through its Secondary Standard Dosimetry Laboratory in the African region. This intercomparison exercise was aimed at verifying the performance of the individual monitoring services of the participants in order to assess their capabilities to measure the quantity Hp(10) in photon (gamma and X ray) fields helping them to comply with dose limitation requirements. The scope of this intercomparison was aimed at passive dosemeters, which determine the personal dose equivalent in photon radiation fields, mainly for thermoluminescence and optically stimulated luminescence dosemeters. Twenty-seven countries from the Africa region and from outside Africa participated in this exercise. The intercomparison protocol, including the preparation of the dosemeters and the irradiation procedures, is described and the results are presented, analysed and discussed.

  18. Dosimetric optimization of a conical breast brachytherapy applicator for improved skin dose sparing

    SciTech Connect

    Yang Yun; Rivard, Mark J.

    2010-11-15

    Purpose: Both the AccuBoost D-shaped and round applicators have been dosimetrically characterized and clinically used to treat patients with breast cancer. While the round applicators provide conformal dose coverage, under certain clinical circumstances the breast skin dose may be higher than preferred. The purpose of this study was to modify the round applicators to minimize skin dose while not substantially affecting dose uniformity within the target volume and reducing the treatment time. Methods: In order to irradiate the intended volume while sparing critical structures such as the skin, the current round applicator design has been augmented through the addition of an internal truncated cone (i.e., frustum) shield. Monte Carlo methods and clinical constraints were used to design the optimal cone applicator. With the cone applicator now defined as the entire assembly including the surrounding tungsten-alloy shell holding the HDR {sup 192}Ir source catheter, the applicator height was reduced to diminish the treatment time while minimizing skin dose. Monte Carlo simulation results were validated using both radiochromic film and ionization chamber measurements based on established techniques. Results: The optimal cone applicators diminished the maximum skin dose by 15%-32% (based on the applicator diameter and breast separation) with the tumor dose reduced by less than 3% for a constant exposure time. Furthermore, reduction in applicator height diminished the treatment time by up to 30%. Radiochromic film and ionization chamber dosimetric results in phantom agreed with Monte Carlo simulation results typically within 3%. Larger differences were outside the treatment volume in low dose regions or associated with differences between the measurement and Monte Carlo simulation environments. Conclusions: A new radiotherapy treatment device was developed and dosimetrically characterized. This set of applicators significantly reduces the skin dose and treatment time while

  19. Dosimetric optimization of a conical breast brachytherapy applicator for improved skin dose sparing.

    PubMed

    Yang, Yun; Rivard, Mark J

    2010-11-01

    Both the AccuBoost D-shaped and round applicators have been dosimetrically characterized and clinically used to treat patients with breast cancer. While the round applicators provide conformal dose coverage, under certain clinical circumstances the breast skin dose may be higher than preferred. The purpose of this study was to modify the round applicators to minimize skin dose while not substantially affecting dose uniformity within the target volume and reducing the treatment time. In order to irradiate the intended volume while sparing critical structures such as the skin, the current round applicator design has been augmented through the addition of an internal truncated cone (i.e., frustum) shield. Monte Carlo methods and clinical constraints were used to design the optimal cone applicator. With the cone applicator now defined as the entire assembly including the surrounding tungsten-alloy shell holding the HDR 192Ir source catheter, the applicator height was reduced to diminish the treatment time while minimizing skin dose. Monte Carlo simulation results were validated using both radiochromic film and ionization chamber measurements based on established techniques. The optimal cone applicators diminished the maximum skin dose by 15%-32% (based on the applicator diameter and breast separation) with the tumor dose reduced by less than 3% for a constant exposure time. Furthermore, reduction in applicator height diminished the treatment time by up to 30%. Radiochromic film and ionization chamber dosimetric results in phantom agreed with Monte Carlo simulation results typically within 3%. Larger differences were outside the treatment volume in low dose regions or associated with differences between the measurement and Monte Carlo simulation environments. A new radiotherapy treatment device was developed and dosimetrically characterized. This set of applicators significantly reduces the skin dose and treatment time while retaining uniform target dose.

  20. Investigating the sonophoresis effect on the permeation of diclofenac sodium using 3D skin equivalent.

    PubMed

    Aldwaikat, Mai; Alarjah, Mohammed

    2015-01-01

    Ultrasound temporally increases skin permeability by altering stratum corneum SC function (sonophoresis). The objective of this study was to evaluate the effect of variable ultrasound conditions on the permeation of diclofenac sodium DS with range of physicochemical properties through EpiDerm™. Permeation studies were carried out in vitro using Franz diffusion cell. HPLC method was used for the determination of the concentration of diclofenac sodium in receiving compartment. Parameters like ultrasound frequency, application time, amplitude, and mode of sonication and distance of ultrasound horn from skin were investigated, and the conditions where the maximum enhancement rate obtained were determined. Application of ultrasound enhanced permeation of diclofenac sodium across EpiDerm™ by fivefolds. The most effective enhancing parameters were power sonication of 20kHz frequency, 20% amplitude at continuous mode for 5min.

  1. 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.

  2. Time and dose-response effects of honokiol on UVB-induced skin cancer development.

    PubMed

    Guillermo, Ruth F; Chilampalli, Chandeshwari; Zhang, Xiaoying; Zeman, David; Fahmy, Hesham; Dwivedi, Chandradhar

    2012-06-01

    Honokiol has shown chemopreventive effects in chemically-induced and UVB-induced skin cancer in mice. In this investigation, we assessed the time-effects of a topical low dose of honokiol (30 μg), and then the effects of different honokiol doses (30, 45, and 60 μg) on a UVB-induced skin cancer model to find an optimal dose and time for desirable chemopreventive effects. UVB radiation (30 mJ/cm(2), 5 days/week for 25 or 27 weeks) was used to induce skin carcinogenesis in SKH-1 mice. For the time-response experiment 30 μg honokiol in acetone was applied topically to the animals before the UVB exposure (30 min, 1 h, and 2 h) and after the UVB exposure (immediately, 30 min, and 1 h). Control groups were treated with acetone. For the dose-response study, animals were treated topically with acetone or honokiol (30, 45, and 60 μg) one hour before the UVB exposure. In the time-response experiment, honokiol inhibited skin tumor multiplicity by 49-58% while reducing tumor volumes by 70-89%. In the dose-response study, honokiol (30, 45, and 60 μg) significantly decreased skin tumor multiplicity by 36-78% in a dose-dependent manner, while tumor area was reduced by 76-94%. Honokiol (60 μg) significantly reduced tumor incidence by 40% as compared to control group. Honokiol applied in very low doses (30 μg) either before or after UVB radiation shows chemopreventive effects. Honokiol (30, 45, and 60 μg) prevents UVB-induced skin cancer in a dose-dependent manner. Honokiol can be an effective chemopreventive agent against skin cancer.

  3. Attenuated kallikrein-related peptidase activity disrupts desquamation and leads to stratum corneum thickening in human skin equivalent models.

    PubMed

    McGovern, J A; Meinert, C; de Veer, S J; Hollier, B G; Parker, T J; Upton, Z

    2017-01-01

    Epidermal homeostasis is maintained through the balance between keratinocyte proliferation, differentiation and desquamation; however, human skin equivalent (HSE) models are known to differentiate excessively. In native tissue, proteases such as kallikrein-related peptidase (KLK) 5 and KLK7 cleave the extracellular components of corneodesmosomes; proteins corneodesmosin, desmocollin 1 and desmoglein 1, loosening the cellular connections and enabling desquamation. The actions of KLK7 are tightly controlled by protease inhibitors, skin-derived antileucoproteinase (SKALP) and lymphoepithelial Kazal-type-related inhibitor (LEKTI), which also inhibits KLK5, localizing protease activity to the stratum corneum. To investigate the mechanisms that inhibit the desquamation cascade in HSE models. Human skin tissue and HSE models were investigated using gene microarray, real-time polymerase chain reaction (PCR), immunohistochemistry and Western blot analysis to examine key components of the desquamation pathway. To elucidate proteolytic activity in HSEs and native skin, in situ and gel zymography was performed. Histological analysis indicated that HSE models form a well-organized epidermis, yet develop an excessively thick and compact stratum corneum. Gene microarray analysis revealed that the desquamation cascade was dysregulated in HSE models and this was confirmed using real-time PCR and immunohistochemistry. Immunohistochemistry and Western blot indicated overexpression of LEKTI and SKALP in HSEs. Although KLK7 was also highly expressed in HSEs, zymography indicated that protease activation and activity was lower than in native skin. These findings demonstrate that stratum corneum thickening is due to inhibited KLK5 and KLK7 activation and a subsequent lack of corneodesmosome degradation in the HSE model epidermis. © 2016 British Association of Dermatologists.

  4. CCL5 and CCL20 mediate immigration of Langerhans cells into the epidermis of full thickness human skin equivalents.

    PubMed

    Ouwehand, Krista; Spiekstra, Sander W; Waaijman, Taco; Breetveld, Melanie; Scheper, Rik J; de Gruijl, Tanja D; Gibbs, Susan

    2012-10-01

    Epidermal Langerhans cells (LC) play a key role in initiation and regulation of immune responses. Whereas LC migration out of the epidermis upon environmental assault is extensively studied, the mechanisms involved in the (re)population of the epidermis with LC are poorly understood. Here, we investigated the immigration of LC derived from the human MUTZ-3 cell line (MUTZ-LC) into the epidermis of a full thickness skin equivalent, comprising a fully differentiated epidermis on a fibroblast-populated dermis. MUTZ-LC were used to determine which epidermis-derived chemokines play a role in mediating LC trans-dermal migration into the epidermis. We found evidence for a role of keratinocyte-derived CCL5 and CCL20 in the chemo-attraction of MUTZ-LC. Neutralizing antibodies against CCL5 and CCL20 blocked LC migration towards keratinocytes. Secretion of these two chemokines was associated with incorporation of MUTZ-LC into the epidermis of full thickness skin equivalents. In conclusion, our findings suggest that epidermis derived CCL5 and CCL20 are pivotal mediators in recruitment of LC into the epidermis.

  5. 10 CFR 20.1201 - Occupational dose limits for adults.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) The annual limits to the lens of the eye, to the skin of the whole body, and to the skin of the... 50 rem (0.5 Sv) to the skin of the whole body or to the skin of any extremity. (b) Doses received in... equivalent must be the dose averaged over the contiguous 10 square centimeters of skin receiving the...

  6. 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.

  7. Acceleration of Apoptosis by Extracellular Basic pH in a 3D Human Skin Equivalent System.

    PubMed

    Park, Gunhyuk; Oh, Dal-Seok; Kim, Yong-Ung; Park, Moon Ki

    2017-01-01

    Previously, we have shown that extracellular basic pH plays a significant role in both the direct and indirect regulation of cellular processes in a wound; this in turn affects the wound-healing process. Several studies have demonstrated the importance of apoptosis modulation in the wound-healing process, especially in removing inflammatory cells and in inhibiting scar formation. However, the effects of extracellular basic pH on wound healing-related skin damage are yet to be examined. Therefore, we investigated the induction of accelerated apoptosis by extracellular basic pH in skin. Apoptosis-related protein levels were measured using an array kit, target protein expression levels were detected by immunostaining, lactate dehydrogenase was analyzed spectrophotometrically, and Annexin V levels were measured by fluorescence staining. Basic pH (8.40) strongly upregulated extrinsic apoptosis proteins (Fas, high temperature requirement A, and p21) and slightly upregulated intrinsic apoptosis proteins (cytochrome c, B-cell lymphoma 2 [Bcl-2], Bcl-2-associated death promoter, and Bcl-2-like protein 4) in a 3D human skin equivalent system. Moreover, basic pH (8.40) induced heat shock protein (HSP) 60 and 70. In addition, basic pH-exposed Fas- and HSP60-knockdown cells showed significantly decreased levels of apoptosis. Taken together, these results indicate that extracellular basic pH increases early-stage apoptosis through Fas/FasL via modulation of HSP60 and HSP70. © 2017 S. Karger AG, Basel.

  8. Electrospun poly(hydroxybutyrate) scaffolds promote engraftment of human skin equivalents via macrophage M2 polarization and angiogenesis.

    PubMed

    Castellano, Delia; Sanchis, Ana; Blanes, María; Pérez Del Caz, Mª Dolores; Ruiz-Saurí, Amparo; Piquer-Gil, Marina; Pelacho, Beatriz; Marco, Bruno; Garcia, Nahuel; Ontoria-Oviedo, Imelda; Cambra, Vicente; Prosper, Felipe; Sepúlveda, Pilar

    2017-01-23

    Human dermo-epidermal skin equivalents (DE) comprising in vitro expanded autologous keratinocytes and fibroblasts are a good option for massive burn treatment. However, the lengthy expansion time required to obtain sufficient surface to cover an extensive burn together with the challenging surgical procedure limits their clinical use. The integration of DE and biodegradable scaffolds has been proposed in an effort to enhance their mechanical properties. Here, it is shown that poly(hydroxybutyrate) electrospun scaffolds (PHB) present good biocompatibility both in vitro and in vivo and are superior to poly-ε-caprolactone electrospun scaffolds as a substrate for skin reconstruction. Implantation of PHB scaffolds in healthy rats polarized macrophages to an M2-type that promoted constructive in vivo remodelling. Moreover, implantation of DE-PHB composites in a NOD/SCID mouse xenograft model resulted in engraftment accompanied by an increase in angiogenesis that favoured the survival of the human graft. Thus, PHB scaffolds are an attractive substrate for further exploration in skin reconstruction procedures, probably due in part to their greater angiogenic and M2 macrophage polarization properties. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  9. Histiocytic tumor of Meckel's cave. An intracranial equivalent of juvenile xanthogranuloma of the skin.

    PubMed

    Paulus, W; Kirchner, T; Michaela, M; Kühl, J; Warmuth-Metz, M; Sörensen, N; Müller-Hermelink, H K; Roggendorf, W

    1992-01-01

    We present the case of a 7-year-old boy who had a solitary mass within Meckel's cave that recurred 6 weeks after the initial resection. The histological, immunohistochemical, electron-microscopical, and molecular genetical features established the lesion's histiocytic nature. Our findings showed that it was closely related to juvenile xanthogranuloma, a benign lesion that usually occurs in the skin but has not yet been histologically confirmed in the brain. The present tumor is different from other intracranial histiocytic and xanthogranulomatous lesions.

  10. Measuring the skin dose protection afforded by protective apparel with a beta spectrometer

    SciTech Connect

    Martz, D.E.; Rich, B.L.; Johnson, L.O. )

    1986-10-01

    This paper reports that the protective apparel worn by radiation workers to avoid skin contamination also provides measurable protection against external beta sources. The beta contribution to the skin dose rate depends on the residual energy spectrum of the beta particles after they have penetrated the protective apparel. The shift in the beta energy spectra and consequent reduction in the shallow dose rates afforded by various items of protective apparel were investigated for a few laboratory beta sources using a beta spectrometer that is capable of dose calculations. The results presented here indicate that significant dose rates to the skin can occur despite the presence of protective apparel if high energy beta emitting isotopes are present.

  11. Evaluating the consistency of location of the most severe acute skin reaction and highest skin dose measured by thermoluminescent dosimeter during radiotherapy for breast cancer.

    PubMed

    Sun, Li-Min; Huang, Chih-Jen; Chen, Hsiao-Yun; Chang, Gia-Hsin; Tsao, Min-Jen

    2016-01-01

    We conducted this prospective study to evaluate whether the location of the most severe acute skin reaction matches the highest skin dose measured by thermoluminescent dosimeter (TLD) during adjuvant radiotherapy (RT) for patients with breast cancer after breast conservative surgery. To determine whether TLD measurement can reflect the location of the most severe acute skin reaction, 80 consecutive patients were enrolled in this prospective study. We divided the irradiated field into breast, axillary, inframammary fold, and areola/nipple areas. In 1 treatment session when obvious skin reaction occurred, we placed the TLD chips onto the 4 areas and measured the skin dose. We determined whether the highest measured skin dose area is consistent with the location of the most severe skin reaction. The McNemar test revealed that the clinical skin reaction and TLD measurement are more consistent when the most severe skin reaction occurred at the axillary area, and the p = 0.0108. On the contrary, TLD measurement of skin dose is less likely consistent with clinical observation when the most severe skin reaction occurred at the inframammary fold, breast, and areola/nipple areas (all the p > 0.05). Considering the common site of severe skin reaction over the axillary area, TLD measurement may be an appropriate way to predict skin reaction during RT. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  12. Assessment of the effective dose equivalent for external photon radiation. Volume 1, Calculational results for beam and point source geometries: Final report

    SciTech Connect

    Reece, W.D.; Poston, J.W.; Xu, X.G.

    1993-02-01

    Beginning in January 1994, US nuclear power plants must change the way that they determine the radiation exposure to their workforce. At that time, revisions to Title 10 Part 20 of the Code of Federal Regulations will be in force requiring licensees to evaluate worker radiation exposure using a risk-based methodology termed the ``effective dose equivalent.`` A research project was undertaken to improve upon the conservative method presently used for assessing effective dose equivalent. In this project effective dose equivalent was calculated using a mathematical model of the human body, and tracking photon interactions for a wide variety of radiation source geometries using Monte Carlo computer code simulations. Algorithms were then developed to relate measurements of the photon flux on the surface of the body (as measured by dosimeters) to effective dose equivalent. This report (Volume I of a two-part study) describes: the concept of effective dose equivalent, the evolution of the concept and its incorporation into regulations, the variations in human organ susceptibility to radiation, the mathematical modeling and calculational techniques used, the results of effective dose equivalent calculations for a broad range of photon energiesand radiation source geometries. The study determined that for beam radiation sources the highest effective dose equivalent occurs for beams striking the front of the torso. Beams striking the rear of the torsoproduce the next highest effective dose equivalent, with effective dose equivalent falling significantly as one departs from these two orientations. For point sources, the highest effective dose equivalent occurs when the sources are in contact with the body on the front of the torso. For females the highest effective dose equivalent occurs when the source is on the sternum, for males when it is on the gonads.

  13. Maculopapular skin rashes associated with high-dose chemotherapy: prevalence and risk factors.

    PubMed

    Wright, Lynette G

    2006-11-27

    To determine the prevalence of and risk factors for maculopapular skin rashes associated with high-dose chemotherapy. Observational pilot study. A bone marrow transplant hematology-oncology unit in a private city hospital. Data were collected on 14 patients who developed maculopapular rashes out of 127 patients who received high-dose chemotherapy (purposive sampling). Observation of the distribution and nature of skin rashes in relation to chemotherapy, disease, adjuvant medications, and white blood cell counts. Diseases, chemotherapy protocols and doses, adjuvant medications, and blood counts. Skin reactions ranged from mild, scattered macular or maculopapular rashes to severe rashes. Patients newly diagnosed with acute myelogenous leukemia (AML) who received induction protocols containing cytarabine had the most rashes, affecting 6 of 11 patients (55%). No rashes were observed on patients treated with the protocol that included high-dose corticosteroids. Patients rarely had recurrence of the rash with further courses of chemotherapy. Cytarabine doses higher than 700 mg/m2 may be a cause of maculopapular skin rashes. Patients most at risk were those newly diagnosed with AML who received induction therapy. Corticosteroids may prevent the development of skin rashes. No useful nursing strategy exists to prevent, lessen the intensity of, or shorten the course of a delayed hypersensitivity rash. Knowing which patients are most at risk is useful to enable close monitoring and patient and staff education.

  14. Potent response of QS-21 as a vaccine adjuvant in the skin when delivered with the Nanopatch, resulted in adjuvant dose sparing

    PubMed Central

    Ng, Hwee-Ing; Fernando, Germain J. P.; Depelsenaire, Alexandra C. I.; Kendall, Mark A. F.

    2016-01-01

    Adjuvants play a key role in boosting immunogenicity of vaccines, particularly for subunit protein vaccines. In this study we investigated the induction of antibody response against trivalent influenza subunit protein antigen and a saponin adjuvant, QS-21. Clinical trials of QS-21 have demonstrated the safety but, also a need of high dose for optimal immunity, which could possibly reduce patient acceptability. Here, we proposed the use of a skin delivery technology – the Nanopatch – to reduce both adjuvant and antigen dose but also retain its immune stimulating effects when compared to the conventional needle and syringe intramuscular (IM) delivery. We have demonstrated that Nanopatch delivery to skin requires only 1/100th of the IM antigen dose to induce equivalent humoral response. QS-21 enhanced humoral response in both skin and muscle route. Additionally, Nanopatch has demonstrated 30-fold adjuvant QS-21 dose sparing while retaining immune stimulating effects compared to IM. QS-21 induced localised, controlled cell death in the skin, suggesting that the danger signals released from dead cells contributed to the enhanced immunogenicity. Taken together, these findings demonstrated the suitability of reduced dose of QS-21 and the antigen using the Nanopatch to enhance humoral responses, and the potential to increase patient acceptability of QS-21 adjuvant. PMID:27404789

  15. Potent response of QS-21 as a vaccine adjuvant in the skin when delivered with the Nanopatch, resulted in adjuvant dose sparing.

    PubMed

    Ng, Hwee-Ing; Fernando, Germain J P; Depelsenaire, Alexandra C I; Kendall, Mark A F

    2016-07-11

    Adjuvants play a key role in boosting immunogenicity of vaccines, particularly for subunit protein vaccines. In this study we investigated the induction of antibody response against trivalent influenza subunit protein antigen and a saponin adjuvant, QS-21. Clinical trials of QS-21 have demonstrated the safety but, also a need of high dose for optimal immunity, which could possibly reduce patient acceptability. Here, we proposed the use of a skin delivery technology - the Nanopatch - to reduce both adjuvant and antigen dose but also retain its immune stimulating effects when compared to the conventional needle and syringe intramuscular (IM) delivery. We have demonstrated that Nanopatch delivery to skin requires only 1/100(th) of the IM antigen dose to induce equivalent humoral response. QS-21 enhanced humoral response in both skin and muscle route. Additionally, Nanopatch has demonstrated 30-fold adjuvant QS-21 dose sparing while retaining immune stimulating effects compared to IM. QS-21 induced localised, controlled cell death in the skin, suggesting that the danger signals released from dead cells contributed to the enhanced immunogenicity. Taken together, these findings demonstrated the suitability of reduced dose of QS-21 and the antigen using the Nanopatch to enhance humoral responses, and the potential to increase patient acceptability of QS-21 adjuvant.

  16. 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.

  17. 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.

  18. 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.

  19. Reconstruction of dose equivalents to the public from the sup 60 Co Irradiator Facility at the Laboratory for Energy-Related Health Research

    SciTech Connect

    Chapman, T.E.; Scherpelz, R.I.

    1991-03-01

    Because of the uncertainties associated with the dose equivalents received by the public, the DOE has tasked Environmental Management Operations (EMO), as part of the LEHR Environmental Restoration project commissioned by DOE, to reconstruct the dose equivalents received by the public adjacent to the LEHR site. The purpose of this study was to determine the potential radiation dose equivalents received by individuals in publicly accessible areas and to provide estimates of the associated risks to these individuals from the outdoor irradiations. EMO has reconstructed the radiation dose equivalent rates to the offsite areas using actual environmental radiation monitoring data augmented by Monte Carlo computer modeling of the radiation dose equivalent rates where necessary. This report describes the irradiator and adjacent areas, available environmental radiation data, the computer modeling and dose equivalent rate projections, occupancy determinations, and reconstructed dose equivalents. A risk factor is estimated for each of the dose equivalents calculated for the public. Traditional units are used throughout this report rather than SI (metric) units for reasons of clarity. 4 refs., 3 figs., 6 tabs.

  20. Non-invasive continuous imaging of drug release from soy-based skin equivalent using wide-field interferometry

    NASA Astrophysics Data System (ADS)

    Gabai, Haniel; Baranes-Zeevi, Maya; Zilberman, Meital; Shaked, Natan T.

    2013-04-01

    We propose an off-axis interferometric imaging system as a simple and unique modality for continuous, non-contact and non-invasive wide-field imaging and characterization of drug release from its polymeric device used in biomedicine. In contrast to the current gold-standard methods in this field, usually based on chromatographic and spectroscopic techniques, our method requires no user intervention during the experiment, and only one test-tube is prepared. We experimentally demonstrate imaging and characterization of drug release from soy-based protein matrix, used as skin equivalent for wound dressing with controlled anesthetic, Bupivacaine drug release. Our preliminary results demonstrate the high potential of our method as a simple and low-cost modality for wide-field imaging and characterization of drug release from drug delivery devices.

  1. Preparation of a skin equivalent phantom with interior micron-scale vessel structures for optical imaging experiments

    PubMed Central

    Chen, Chen; Klämpfl, Florian; Knipfer, Christian; Riemann, Max; Kanawade, Rajesh; Stelzle, Florian; Schmidt, Michael

    2014-01-01

    A popular alternative of preparing multilayer or microfluidic chip based phantoms could have helped to simulate the subsurface vascular network, but brought inevitable problems. In this work, we describe the preparation method of a single layer skin equivalent tissue phantom containing interior vessel channels, which mimick the superficial microvascular structure. The fabrication method does not disturb the optical properties of the turbiding matrix material. The diameter of the channels reaches a value of 50 μm. The size, as well as the geometry of the generated vessel structures are investigated by using the SD-OCT system. Our preliminary results confirm that fabrication of such a phantom is achievable and reproducible. Prospectively, this phantom is used to calibrate the optical angiographic imaging approaches. PMID:25401027

  2. Preparation of a skin equivalent phantom with interior micron-scale vessel structures for optical imaging experiments.

    PubMed

    Chen, Chen; Klämpfl, Florian; Knipfer, Christian; Riemann, Max; Kanawade, Rajesh; Stelzle, Florian; Schmidt, Michael

    2014-09-01

    A popular alternative of preparing multilayer or microfluidic chip based phantoms could have helped to simulate the subsurface vascular network, but brought inevitable problems. In this work, we describe the preparation method of a single layer skin equivalent tissue phantom containing interior vessel channels, which mimick the superficial microvascular structure. The fabrication method does not disturb the optical properties of the turbiding matrix material. The diameter of the channels reaches a value of 50 μm. The size, as well as the geometry of the generated vessel structures are investigated by using the SD-OCT system. Our preliminary results confirm that fabrication of such a phantom is achievable and reproducible. Prospectively, this phantom is used to calibrate the optical angiographic imaging approaches.

  3. Estimation of Errors Associated With Use of Linear-Quadratic Formalism for Evaluation of Biologic Equivalence Between Single and Hypofractionated Radiation Doses: An In Vitro Study

    SciTech Connect

    Iwata, Hiromitsu Shibamoto, Yuta; Murata, Rumi; Tomita, Natsuo; Ayakawa, Shiho; Ogino, Hiroyuki; Ito, Masato

    2009-10-01

    Purpose: To investigate the reliability of the linear-quadratic (LQ) formalism and the magnitude of errors associated with its use in assessing biologic equivalence between single, high radiation doses and hypofractionated radiation doses. Methods and Materials: V79 and EMT6 single cells received single doses of 2-12 Gy or two or three fractions of 4 or 5 Gy, each at 4-h intervals. Single and fractionated doses to actually reduce the cell survival to the same level were determined by a colony assay. The {alpha}/{beta} ratio was obtained from the cell survival curves. Using the {alpha}/{beta} ratio and the LQ formalism, equivalent single doses for the hypofractionated doses were calculated. They were then compared with the actually determined equivalent single doses for the hypofractionated doses. The V79 spheroids received single doses of 5-26 Gy or two to five fractions of 5-12 Gy at 2 or 4-h interval, and then were assayed for cell survival. Next, equivalent single doses for the hypofractionated doses were determined, as were done for the single cells. Results: The {alpha}/{beta} ratio was 5.1 Gy for the V79 single cells and 0.36 Gy for EMT6. In V79, the equivalent single doses for the hypofractionated doses calculated using the LQ formalism were 12-19% lower than the actually measured biologically equivalent single doses. In the EMT6 cells, this trend was also seen, but the differences were not significant. In the V79 spheroids, the calculated doses were 18-30% lower than the measured doses. Conclusion: Conversion of hypofractionated radiation doses to single doses using the LQ formalism could underestimate the effect of hypofractionated radiation by {<=}30%.

  4. Off-axis dose equivalent due to secondary neutrons from uniform scanning proton beams during proton radiotherapy.

    PubMed

    Islam, M R; Collums, T L; Zheng, Y; Monson, J; Benton, E R

    2013-11-21

    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.

  5. 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.

  6. Evaluation of equivalent and effective dose by KAP for patient and orthopedic surgeon in vertebral compression fracture surgery

    NASA Astrophysics Data System (ADS)

    Santos, Felipe A.; Galeano, Diego C.; Santos, William S.; Silva, Ademir X.; Souza, Susana O.; Carvalho Júnior, Albérico B.

    2017-03-01

    Clinical scenarios were virtually modeled to estimate both the equivalent and effective doses normalized by KAP (Kerma Area Product) to vertebra compression fracture surgery in patient and surgeon. This surgery is known as kyphoplasty and involves the use of X-ray equipment, the C-arm, which provides real-time images to assist the surgeon in conducting instruments inserted into the patient and in the delivery of surgical cement into the fractured vertebra. The radiation transport code used was MCNPX (Monte Carlo N-Particle eXtended) and a pair of UFHADM (University of Florida Hybrid ADult Male) virtual phantoms. The developed scenarios allowed us to calculate a set of equivalent dose (HT) and effective dose (E) for patients and surgeons. In additional, the same scenario was calculated KAP in the tube output and was used for calculating conversion coefficients (E/KAP and HT/KAP). From the knowledge of the experimental values of KAP and the results presented in this study, it is possible to estimate absolute values of effective doses for different exposure conditions. In this work, we developed scenarios with and without the surgical table with the purpose of comparison with the existing data in the literature. The absence of the bed in the scenario promoted a percentage absolute difference of 56% in the patient effective doses in relation to scenarios calculated with a bed. Regarding the surgeon, the use of the personal protective equipment (PPE) reduces between 75% and 79% the effective dose and the use of the under table shield (UTS) reduces the effective dose of between 3% and 7%. All these variations emphasize the importance of the elaboration of virtual scenarios that approach the actual clinical conditions generating E/KAP and HT/KAP closer to the actual values.

  7. Dose equivalent near the bone-soft tissue interface from nuclear fragments produced by high-energy protons

    NASA Technical Reports Server (NTRS)

    Shavers, M. R.; Poston, J. W.; Cucinotta, F. A.; Wilson, J. W.

    1996-01-01

    During manned space missions, high-energy nucleons of cosmic and solar origin collide with atomic nuclei of the human body and produce a broad linear energy transfer spectrum of secondary particles, called target fragments. These nuclear fragments are often more biologically harmful than the direct ionization of the incident nucleon. That these secondary particles increase tissue absorbed dose in regions adjacent to the bone-soft tissue interface was demonstrated in a previous publication. To assess radiological risks to tissue near the bone-soft tissue interface, a computer transport model for nuclear fragments produced by high energy nucleons was used in this study to calculate integral linear energy transfer spectra and dose equivalents resulting from nuclear collisions of 1-GeV protons transversing bone and red bone marrow. In terms of dose equivalent averaged over trabecular bone marrow, target fragments emitted from interactions in both tissues are predicted to be at least as important as the direct ionization of the primary protons-twice as important, if recently recommended radiation weighting factors and "worst-case" geometry are used. The use of conventional dosimetry (absorbed dose weighted by aa linear energy transfer-dependent quality factor) as an appropriate framework for predicting risk from low fluences of high-linear energy transfer target fragments is discussed.

  8. Dose equivalent near the bone-soft tissue interface from nuclear fragments produced by high-energy protons

    NASA Technical Reports Server (NTRS)

    Shavers, M. R.; Poston, J. W.; Cucinotta, F. A.; Wilson, J. W.

    1996-01-01

    During manned space missions, high-energy nucleons of cosmic and solar origin collide with atomic nuclei of the human body and produce a broad linear energy transfer spectrum of secondary particles, called target fragments. These nuclear fragments are often more biologically harmful than the direct ionization of the incident nucleon. That these secondary particles increase tissue absorbed dose in regions adjacent to the bone-soft tissue interface was demonstrated in a previous publication. To assess radiological risks to tissue near the bone-soft tissue interface, a computer transport model for nuclear fragments produced by high energy nucleons was used in this study to calculate integral linear energy transfer spectra and dose equivalents resulting from nuclear collisions of 1-GeV protons transversing bone and red bone marrow. In terms of dose equivalent averaged over trabecular bone marrow, target fragments emitted from interactions in both tissues are predicted to be at least as important as the direct ionization of the primary protons-twice as important, if recently recommended radiation weighting factors and "worst-case" geometry are used. The use of conventional dosimetry (absorbed dose weighted by aa linear energy transfer-dependent quality factor) as an appropriate framework for predicting risk from low fluences of high-linear energy transfer target fragments is discussed.

  9. A practical method for skin dose estimation in interventional cardiology based on fluorographic DICOM information.

    PubMed

    Matthews, Lucy; Dixon, Matthew; Rowles, Nick; Stevens, Greg

    2016-03-01

    A practical method for skin dose estimation for interventional cardiology patients has been developed to inform pre-procedure planning and post-procedure patient management. Absorbed dose to the patient skin for certain interventional radiology procedures can exceed thresholds for deterministic skin injury, requiring documentation within the patient notes and appropriate patient follow-up. The primary objective was to reduce uncertainty associated with current methods, particularly surrounding field overlap. This was achieved by considering rectangular field geometry incident on a spherical patient model in a polar coordinate system. The angular size of each field was quantified at surface of the sphere, i.e. the skin surface. Computer-assisted design software enabled the modelling of a sufficient dataset that was subsequently validated with radiochromic film. Modelled overlap was found to agree with overlap measured using film to within 2.2° ± 2.0°, showing that the overall error associated with the model was < 1 %. Mathematical comparison against exposure data extracted from procedural Digital Imaging and Communication in Medicine files was used to generate a graphical skin dose map, demonstrating the dose distribution over a sphere centred at the interventional reference point. Dosimetric accuracy of the software was measured as between 3.5 and 17 % for different variables.

  10. Clinical implementation of total skin electron irradiation treatment with a 6 MeV electron beam in high-dose total skin electron mode

    NASA Astrophysics Data System (ADS)

    Lucero, J. F.; Rojas, J. I.

    2016-07-01

    Total skin electron irradiation (TSEI) is a special treatment technique offered by modern radiation oncology facilities, given for the treatment of mycosis fungoides, a rare skin disease, which is type of cutaneous T-cell lymphoma [1]. During treatment the patient's entire skin is irradiated with a uniform dose. The aim of this work is to present implementation of total skin electron irradiation treatment using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films.

  11. Milk phospholipid's protective effects against UV damage in skin equivalent models

    NASA Astrophysics Data System (ADS)

    Dargitz, Carl; Russell, Ashley; Bingham, Michael; Achay, Zyra; Jimenez-Flores, Rafael; Laiho, Lily H.

    2012-03-01

    Exposure of skin tissue to UV radiation has been shown to cause DNA photodamage. If this damaged DNA is allowed to replicate, carcinogenesis may occur. DNA damage is prevented from being passed on to daughter cells by upregulation of the protein p21. p21 halts the cells cycle allowing the cell to undergo apoptosis, or repair its DNA before replication. Previous work suggested that milk phospholipids may possess protective properties against UV damage. In this study, we observed cell morphology, cell apoptosis, and p21 expression in tissue engineered epidermis through the use of Hematoxylin and Eosin staining, confocal microscopy, and western blot respectively. Tissues were divided into four treatment groups including: a control group with no UV and no milk phospholipid treatment, a group exposed to UV alone, a group incubated with milk phospholipids alone, and a group treated with milk phospholipids and UV. All groups were incubated for twenty-four hours after treatment. Tissues were then fixed, processed, and embedded in paraffin. Performing western blots resulted in visible p21 bands for the UV group only, implying that in every other group, p21 expression was lesser. Numbers of apoptotic cells were determined by observing the tissues treated with Hoechst dye under a confocal microscope, and counting the number of apoptotic and total cells to obtain a percentage of apoptotic cells. We found a decrease in apoptotic cells in tissues treated with milk phospholipids and UV compared to tissues exposed to UV alone. Collectively, these results suggest that milk phospholipids protect cell DNA from damage incurred from UV light.

  12. A Real-Time Skin Dose Tracking System for Biplane Neuro-Interventional Procedures

    PubMed Central

    Rana, Vijay K.; Rudin, Stephen; Bednarek, Daniel R.

    2015-01-01

    A biplane dose-tracking system (Biplane-DTS) that provides a real-time display of the skin-dose distribution on a 3D-patient graphic during neuro-interventional fluoroscopic procedures was developed. Biplane-DTS calculates patient skin dose using geometry and exposure information for the two gantries of the imaging system acquired from the digital system bus. The dose is calculated for individual points on the patient graphic surface for each exposure pulse and cumulative dose for both x-ray tubes is displayed as color maps on a split screen showing frontal and lateral projections of a 3D-humanoid graphic. Overall peak skin dose (PSD), FOV-PSD and current dose rates for the two gantries are also displayed. Biplane-DTS uses calibration files of mR/mAs for the frontal and lateral tubes measured with and without the table in the beam at the entrance surface of a 20 cm thick PMMA phantom placed 15 cm tube-side of the isocenter. For neuro-imaging, conversion factors are applied as a function of entrance field area to scale the calculated dose to that measured with a Phantom Laboratory head phantom which contains a human skull to account for differences in backscatter between PMMA and the human head. The software incorporates inverse-square correction to each point on the skin and corrects for angulation of the beam through the table. Dose calculated by Biplane DTS and values measured by a 6-cc ionization chamber placed on the head phantom at multiple points agree within a range of −3% to +7% with a standard deviation for all points of less than 3%. PMID:26430290

  13. A real-time skin dose tracking system for biplane neuro-interventional procedures

    NASA Astrophysics Data System (ADS)

    Rana, Vijay K.; Rudin, Stephen R.; Bednarek, Daniel R.

    2015-03-01

    A biplane dose-tracking system (Biplane-DTS) that provides a real-time display of the skin-dose distribution on a 3D-patient graphic during neuro-interventional fluoroscopic procedures was developed. Biplane-DTS calculates patient skin dose using geometry and exposure information for the two gantries of the imaging system acquired from the digital system bus. The dose is calculated for individual points on the patient graphic surface for each exposure pulse and cumulative dose for both x-ray tubes is displayed as color maps on a split screen showing frontal and lateral projections of a 3D-humanoid graphic. Overall peak skin dose (PSD), FOV-PSD and current dose rates for the two gantries are also displayed. Biplane- TS uses calibration files of mR/mAs for the frontal and lateral tubes measured with and without the table in the beam at the entrance surface of a 20 cm thick PMMA phantom placed 15 cm tube-side of the isocenter. For neuro-imaging, conversion factors are applied as a function of entrance field area to scale the calculated dose to that measured with a Phantom Laboratory head phantom which contains a human skull to account for differences in backscatter between PMMA and the human head. The software incorporates inverse-square correction to each point on the skin and corrects for angulation of the beam through the table. Dose calculated by Biplane DTS and values measured by a 6-cc ionization chamber placed on the head phantom at multiple points agree within a range of -3% to +7% with a standard deviation for all points of less than 3%.

  14. Idarubicin appears equivalent to dose-intense daunorubicin for remission induction in patients with acute myeloid leukemia.

    PubMed

    Trifilio, Steven; Zhou, Zheng; Mehta, Jayesh; Czerniak, Colleen; Pi, Judy; Greenberg, Deborah; Koslosky, Molly; Pantiru, Mihaela; Altman, Jessica

    2013-08-01

    Daunorubicin has historically been considered the anthracycline of choice at many cancer centers for the treatment of acute myeloid leukemia (AML). Drug shortages have required the substitution of daunorubicin with idarubicin. Randomized studies have shown idarubicin (10-12mg/m(2)) to be comparable or superior to standard dose daunorubicin (45-60mg/m(2)) for achieving complete remission (CR). Whether these results can be extrapolated to dose-intense daunorubicin (90mg/m(2)), recently shown to improve CR rates when compared to standard daunorubicin doses remains uncertain. This observational study was conducted at Northwestern Memorial Hospital (NMH) to compare CR rates. The results suggest idarubicin is equivalent to daunorubicin, and for some subsets of patients, idarubicin may have superior CR rates.

  15. 40 CFR Appendix A to Part 197 - Calculation of Annual Committed Effective Dose Equivalent

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., being gradually delivered as the radionuclide decays. The time distribution of the absorbed dose rate... following an intake of radioactive material into the body: ER15OC08.002 for a single intake of activity...

  16. 40 CFR Appendix A to Part 197 - Calculation of Annual Committed Effective Dose Equivalent

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., being gradually delivered as the radionuclide decays. The time distribution of the absorbed dose rate... following an intake of radioactive material into the body: ER15OC08.002 for a single intake of activity...

  17. 40 CFR Appendix A to Part 197 - Calculation of Annual Committed Effective Dose Equivalent

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., being gradually delivered as the radionuclide decays. The time distribution of the absorbed dose rate... following an intake of radioactive material into the body: ER15OC08.002 for a single intake of activity...

  18. 40 CFR Appendix A to Part 197 - Calculation of Annual Committed Effective Dose Equivalent

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., being gradually delivered as the radionuclide decays. The time distribution of the absorbed dose rate... following an intake of radioactive material into the body: ER15OC08.002 for a single intake of activity...

  19. 40 CFR Appendix A to Part 197 - Calculation of Annual Committed Effective Dose Equivalent

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., being gradually delivered as the radionuclide decays. The time distribution of the absorbed dose rate... following an intake of radioactive material into the body: ER15OC08.002 for a single intake of activity...

  20. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC.

    PubMed

    Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

    2015-11-01

    A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed (28)Al, (24)Na, (54)Mn and (60)Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is (28)Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several (28)Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received.

  1. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC

    PubMed Central

    Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

    2015-01-01

    A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed 28Al, 24Na, 54Mn and 60Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is 28Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several 28Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received. PMID:26265661

  2. Evaluation of ambient dose equivalent rates influenced by vertical and horizontal distribution of radioactive cesium in soil in Fukushima Prefecture.

    PubMed

    Malins, Alex; Kurikami, Hiroshi; Nakama, Shigeo; Saito, Tatsuo; Okumura, Masahiko; Machida, Masahiko; Kitamura, Akihiro

    2016-01-01

    The air dose rate in an environment contaminated with (134)Cs and (137)Cs depends on the amount, depth profile and horizontal distribution of these contaminants within the ground. This paper introduces and verifies a tool that models these variables and calculates ambient dose equivalent rates at 1 m above the ground. Good correlation is found between predicted dose rates and dose rates measured with survey meters in Fukushima Prefecture in areas contaminated with radiocesium from the Fukushima Dai-ichi Nuclear Power Plant accident. This finding is insensitive to the choice for modeling the activity depth distribution in the ground using activity measurements of collected soil layers, or by using exponential and hyperbolic secant fits to the measurement data. Better predictions are obtained by modeling the horizontal distribution of radioactive cesium across an area if multiple soil samples are available, as opposed to assuming a spatially homogeneous contamination distribution. Reductions seen in air dose rates above flat, undisturbed fields in Fukushima Prefecture are consistent with decrement by radioactive decay and downward migration of cesium into soil. Analysis of remediation strategies for farmland soils confirmed that topsoil removal and interchanging a topsoil layer with a subsoil layer result in similar reductions in the air dose rate. These two strategies are more effective than reverse tillage to invert and mix the topsoil.

  3. Measurement of neutron ambient dose equivalent in carbon-ion radiotherapy with an active scanned delivery system.

    PubMed

    Yonai, S; Furukawa, T; Inaniwa, T

    2014-10-01

    In ion beam radiotherapy, secondary neutrons contribute to an undesired dose outside the target volume, and consequently the increase of secondary cancer risk is a growing concern. In this study, neutron ambient dose equivalents in carbon-ion radiotherapy (CIRT) with an active beam delivery system were measured with a rem meter, WENDI-II, at National Institute of Radiological Sciences. When the same irradiation target was assumed, the measured neutron dose with an active beam was at most ∼15 % of that with a passive beam. This percentage became smaller as larger distances from the iso-centre. Also, when using an active beam delivery system, the neutron dose per treatment dose in CIRT was comparable with that in proton radiotherapy. Finally, it was experimentally demonstrated that the use of an active scanned beam in CIRT can greatly reduce the secondary neutron dose. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Beta skin dose determination using TLDs, Monte-Carlo calculations, and extrapolation chamber.

    PubMed

    Ben-Shachar, B; Levine, S H; Hoffman, J M

    1989-12-01

    The beta doses produced by 90Sr-Y and 204 Tl beta sources were determined using three methods: Monte-Carlo calculations, measurements with TLDs, and measurements with an extrapolation chamber. Excellent agreement was obtained by all three methods, except a TLD nonlinear response to beta s was observed, which gives doses approximately 20% high for the 90Sr-Y source and 5% low for the 204Tl source. Also, analyses performed with low-energy beta s using these methods can determine errors in shield thickness covering TLD elements. Direct measurement of skin dose is not possible by the TLDs because the minimum shield thickness for the elements is 13 mg cm-2. A thinner shield for the elements must be used or the data must be extrapolated. Presently, thinner shields for TLD elements are not available, and the thick shields can lead to significant errors in skin dose when exposed to low-energy beta s.

  5. Radiation Dose to the Skin and to the Gonads from Diagnostic X-Ray Procedures

    PubMed Central

    Duggan, H. E.; Olde, G. L.

    1963-01-01

    The design of a study to assess the hazard to patients from radiation received during diagnostic radiological procedures is described. The long-term accumulation of data relating to the skin and gonadal doses received by patients in a large x-ray department has been initiated. This will serve as a model for any situation involving small recurrent radiation doses to a significant proportion of the population. A description is given of the basic dose measurements made and the method used in calculating and recording the skin and gonadal doses for each patient. Although no definite conclusions concerning the presence or absence of a radiation hazard have yet been made, the proposed future course of this study is discussed. ImagesFig. 3Fig. 4 PMID:14079142

  6. Pharmacodynamic equivalence study of CFC-free and CFC-containing procaterol hydrochloride metered-dose inhalers.

    PubMed

    Kawai, M; Nakashima, M; Takaori, S; Nakamura, Y; Akamatsu, K; Nakashima, M; Miyamoto, T

    2005-10-01

    Equivalence between a CFC-free procaterol hydrochloride metered-dose inhaler using HFA-227 as a propellant (Meptin [HFA]) and a CFC-containing procaterol hydrochloride metered-dose inhaler (Meptin [CFC]) was assessed in 28 patients with bronchial asthma. The study was conducted in a randomized, double-dummy, double-blind crossover manner, using forced expiratory volume in the first second (FEV1) as an index of bronchodilatory effect. In Period I, the patients received 20 microg of either Meptin [HFA] or Meptin [CFC] and then crossed over in Period II after a washout interval of 3-28 days. Pharmacodynamic equivalence was assessed using AUC (FEV1)/h and peak FEV1 as indices, and the data was analyzed by analysis of variance. Factors used for the analysis were the treatment group and/or carryover effect, patients within each group, period, and treatment. The 90% confidence intervals for the differences between the two treatments were -0.0507 to 0.0039 (L) for mean AUC (FEV1)/h and -0.056 to 0.026 (L) for mean peak FEV1, both within the acceptance criteria of -0.15 to 0.15 (L). Meptin [HFA] was therefore assessed as being equivalent to the current Meptin [CFC]. (c) 2005 Prous Science. All rights reserved.

  7. Differential cytokine induction by doses of lipopolysaccharide and monophosphoryl lipid A that result in equivalent early endotoxin tolerance.

    PubMed Central

    Henricson, B E; Benjamin, W R; Vogel, S N

    1990-01-01

    The phenomenon of early endotoxin tolerance, which is induced by sublethal injection of lipopolysaccharide (LPS), results in a protracted period of hyporesponsiveness that is most profound at 3 to 4 days after injection and is marked by reduced cytokine production after a challenge injection of LPS. Early endotoxin tolerance is also induced by the nontoxic LPS derivative monophosphoryl lipid A (MPL), although much more of the monophosphoryl derivative is required to produce a state of tolerance equivalent to that evoked by LPS. In this study, equivalent tolerance-inducing doses of LPS and MPL were tested, and the levels of cytokines induced by LPS and MPL were compared. Although induced levels of colony-stimulating factor were comparable following doses of LPS and MPL that elicited an equivalent state of early endotoxin tolerance, levels of tumor necrosis factor, interleukin-6, and interferon were significantly lower in MPL-injected animals. These results suggest that the lowered toxicity of MPL may be related to its elicitation of significantly lower levels of potentially toxic intermediaries such as tumor necrosis factor, interferon, and interleukin-6. PMID:1695201

  8. Lack of correlation between minimal erythema dose and skin phototype in a Colombian scholar population.

    PubMed

    Sanclemente, Gloria; Zapata, José-F; García, José-J; Gaviria, Angela; Gómez, Luis-F; Barrera, Marcela

    2008-11-01

    Sun exposure and skin phototype are the most relevant risk factors for skin cancer. Colombia has high levels of ultraviolet radiation during the whole year, therefore, both, high UVI's and outdoor worker's daily activities, in our country are very important risk factors for the development of cutaneous cancer. To date no study has evaluated the usefulness of Fitzpatrick's skin phototype classification in Colombians and its correlation with the minimal erythema dose (MED) and constitutional skin color. Such information is gaining importance in other nations due to the fact that several country's population is becoming more ethnically diverse. To determine the skin phototype, accumulated sun exposure, sun protection behavior, MED and phenotype in a Colombian school population. Last year high school students from the western Antioquia were invited to participate by phone and letter through their respective school directors. A self-questionnaire was handled to each student. A representative sample of the universe was selected for a medical examination by a dermatologist in order to validate the results of the self-questionnaire. The constitutional skin color was determined with the chromameter CR 300 Minolta. The MED was defined as the minimal dose of UVB being able to induce erythema 24 h later. Eight schools of the area agreed to participate in the study, and a total of 911 students (58% girls and 42% boys) filled-out the self-questionnaire. Sun exposure in the majority of individuals was in a level between moderate and very high. Ninety percent of students do not use any sun protection device or cream. Only a 50% of concordance between self-assessed skin phototype vs. medical skin phototype was found, and the highest concordance corresponded to skin phototype II (82%). There was a marked difference in skin photosensitivity of Colombians compared with reports in Caucasians. We observed a marked overlapping in MED's and L* values in phototypes II and III. The

  9. Measurement of skin dose from cone-beam computed tomography imaging

    PubMed Central

    2013-01-01

    Objective To measure surface skin dose from various cone-beam computed tomography (CBCT) scanners using point-dosimeters. Materials & methods A head anthropomorphic phantom was used with nanoDOT optically stimulated luminescence (OSL) dosimeters (Landauer Corp., Glenwood, IL) attached to various anatomic landmarks. The phantom was scanned using multiple exposure protocols for craniofacial evaluations in three different CBCT units and a conventional x-ray imaging system. The dosimeters were calibrated for each of the scan protocols on the different imaging systems. Peak skin dose and surface doses at the eye lens, thyroid, submandibular and parotid gland levels were measured. Results The measured skin doses ranged from 0.09 to 4.62 mGy depending on dosimeter positions and imaging systems. The average surface doses to the lens locations were ~4.0 mGy, well below the threshold for cataractogenesis (500 mGy). The results changed accordingly with x-ray tube output (mAs and kV) and also were sensitive to scan field of view (SFOV). As compared to the conventional panoramic and cephalometric imaging system, doses from all three CBCT systems were at least an order of magnitude higher. Conclusions Peak skin dose and surface doses at the eye lens, thyroid, and salivary gland levels measured from the CBCT imaging systems were lower than the thresholds to induce deterministic effects. However, our findings do not justify the routine use of CBCT imaging in orthodontics considering the lifetime-attributable risk to the individual. PMID:24192155

  10. High-dose immunosuppressant alters the immunological status of New Zealand white rabbits following skin transplantation.

    PubMed

    Cheng, Peilun; Zhong, Liming; Jiang, Zesheng; Wang, Yan; Pan, Mingxin; Gao, Y I

    2015-09-01

    The aim of this study was to investigate the effect of an immunosuppressant on the immunological status of New Zealand white rabbits after skin grafting, and to evaluate a method for monitoring the immunological status of subjects with skin transplants. The rabbits were randomly divided into allograft rejection, autograft tolerance, nontransplant, allograft low-dose immunosuppressant and allograft high-dose immunosuppressant groups. The rabbits in the low- and high-dose immunosuppressant groups were treated with cyclosporine A intravenously 8 h prior to skin transplantation and once daily following transplantation at doses of 2 and 25 mg/kg, respectively. At 12 days after skin transplantation, the spleens of donor (female) rabbits and recipient (male) rabbits were harvested for the preparation of single-cell suspensions. The splenocytes from recipient and donor rabbits were labeled with 0.3 or 6 µM carboxy fluorescein diacetate succinimidyl ester, respectively, and a mixed cell suspension was prepared. The final preparation was intravenously injected into recipient New Zealand white rabbits. The ratio of the two fluorescently labeled cell populations in the peripheral blood was measured using flow cytometry at 1, 2, 4 and 8 h after the injection, and the cell death rate was calculated. Histological analysis was also performed on samples collected at the time of splenectomy. The cell death rates of the allograft rejection and low-dose immunosuppressant groups reached their highest levels 8 h after the injection of spleen cell suspension. Allogeneic spleen cells from donor male rabbits were almost completely removed within 8 h of injection. The cell death rate increased slowly in the nontransplant, autograft and high-dose immunosuppressant groups without specificity. This study provides a specific method for the in vivo monitoring of the immunological status of patients after skin grafting. This method can quickly and accurately detect the immunological status of

  11. Automatic monitoring of localized skin dose with fluoroscopic and interventional procedures.

    PubMed

    Khodadadegan, Yasaman; Zhang, Muhong; Pavlicek, William; Paden, Robert G; Chong, Brian; Schueler, Beth A; Fetterly, Kenneth A; Langer, Steve G; Wu, Teresa

    2011-08-01

    This software tool locates and computes the intensity of radiation skin dose resulting from fluoroscopically guided interventional procedures. It is comprised of multiple modules. Using standardized body specific geometric values, a software module defines a set of male and female patients arbitarily positioned on a fluoroscopy table. Simulated X-ray angiographic (XA) equipment includes XRII and digital detectors with or without bi-plane configurations and left and right facing tables. Skin dose estimates are localized by computing the exposure to each 0.01 × 0.01 m(2) on the surface of a patient irradiated by the X-ray beam. Digital Imaging and Communications in Medicine (DICOM) Structured Report Dose data sent to a modular dosimetry database automatically extracts the 11 XA tags necessary for peak skin dose computation. Skin dose calculation software uses these tags (gantry angles, air kerma at the patient entrance reference point, etc.) and applies appropriate corrections of exposure and beam location based on each irradiation event (fluoroscopy and acquistions). A physicist screen records the initial validation of the accuracy, patient and equipment geometry, DICOM compliance, exposure output calibration, backscatter factor, and table and pad attenuation once per system. A technologist screen specifies patient positioning, patient height and weight, and physician user. Peak skin dose is computed and localized; additionally, fluoroscopy duration and kerma area product values are electronically recorded and sent to the XA database. This approach fully addresses current limitations in meeting accreditation criteria, eliminates the need for paper logs at a XA console, and provides a method where automated ALARA montoring is possible including email and pager alerts.

  12. A dosimetric evaluation of tissue equivalent phantom prepared using 270 Bloom gelatin for absorbed dose imaging in Gamma knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Cavinato, C. C.; Rodrigues, O., Jr.; Cervantes, J. H.; Rabbani, S. R.; Campos, L. L.

    2009-05-01

    Tissue equivalent gel phantoms have been widely studied in radiation therapy for both relative and reference dosimetry. A Fricke xylenol gel (FXG) spherical phantom was evaluated by means of magnetic resonance image method (MRI) to measure absorbed dose distribution resulted from gamma knife irradiation. The FXG phantom was prepared using 270 Bloom gelatin. The gelatin is a tissue equivalent material, of easy preparation, can be used to mold phantoms into different shapes and volumes, is commercially available and inexpensive. The results show that the Fricke gel phantom prepared with 270 Bloom gelatin satisfy the requirements to be used for the quality control in stereotactic radiosurgery using Gamma Knife technique and may constitute one more option of dosimeter in radiation therapy applications.

  13. kVCT, MVCT, and hybrid CT image studies-Treatment planning and dose delivery equivalence on helical tomotherapy.

    PubMed

    Martin, Spencer; Yartsev, Slav

    2010-06-01

    To determine the equivalence of radiation therapy treatment planning and delivery for various imaging options on helical tomotherapy. Seven treatment plans using identical anatomy and planning parameters were created based on the following CT studies: Standard kilovoltage CT (kVCT); 2, 4, and 6 mm spacing megavoltage CT (MVCT); and 2, 4, and 6 mm hybrid MVCT/kVCT studies. In addition, two kVCT based plans were created to explore the effect of the choice of dose calculation grid for optimization. Calculated and measured dose distributions were compared via volumetric and dosimetric analysis at the planning stage, point dose measurements with ion chamber, along with EDR2 film data for gamma function analysis for distance to agreement of 3 mm and dose differences of 3%, 5%, and 7% using both the commercially available "cheese" phantom and the new QUASAR Verification (QVer) phantom. Plans created for each imaging option showed residual error increasing as image slice spacing increased and critical structure size decreased. With the exception of the low dose area in hybrid studies, point dose measurements were within the calculated/measured dose acceptance criteria of 5% on both the QVer and cheese phantoms. Gamma analysis for the original kVCT plan delivery showed an average of 98.5%±0.5% and 98.8%±0.3% of dose pixels passing kVCT study treatment and delivery quality assurance procedures, respectively. The QVer phantom allows for delivery quality assurance with simultaneous use of two films and more convenient gamma function assessment but shows some measurement discrepancy up to 10% compared to the cheese phantom. The kVCT, MVCT, and kVCT/MVCT hybrid studies showed considerable agreement at both planning and delivery stages. The choice of calculation grid is more important when dealing with smaller anatomical structures. © 2010 American Association of Physicists in Medicine.

  14. The risk equivalent of an exposure to-, versus a dose of radiation

    SciTech Connect

    Bond, V.P.

    1986-01-01

    The long-term potential carcinogenic effects of low-level exposure (LLE) are addressed. The principal point discussed is linear, no-threshold dose-response curve. That the linear no-threshold, or proportional relationship is widely used is seen in the way in which the values for cancer risk coefficients are expressed - in terms of new cases, per million persons exposed, per year, per unit exposure or dose. This implies that the underlying relationship is proportional, i.e., ''linear, without threshold''. 12 refs., 9 figs., 1 tab.

  15. An Analytical Model of Leakage Neutron Equivalent Dose for Passively-Scattered Proton Radiotherapy and Validation with Measurements

    PubMed Central

    Schneider, Christopher; Newhauser, Wayne; Farah, Jad

    2015-01-01

    Exposure to stray neutrons increases the risk of second cancer development after proton therapy. Previously reported analytical models of this exposure were difficult to configure and had not been investigated below 100 MeV proton energy. The purposes of this study were to test an analytical model of neutron equivalent dose per therapeutic absorbed dose (H/D) at 75 MeV and to improve the model by reducing the number of configuration parameters and making it continuous in proton energy from 100 to 250 MeV. To develop the analytical model, we used previously published H/D values in water from Monte Carlo simulations of a general-purpose beamline for proton energies from 100 to 250 MeV. We also configured and tested the model on in-air neutron equivalent doses measured for a 75 MeV ocular beamline. Predicted H/D values from the analytical model and Monte Carlo agreed well from 100 to 250 MeV (10% average difference). Predicted H/D values from the analytical model also agreed well with measurements at 75 MeV (15% average difference). The results indicate that analytical models can give fast, reliable calculations of neutron exposure after proton therapy. This ability is absent in treatment planning systems but vital to second cancer risk estimation. PMID:25993009

  16. An analytical model of leakage neutron equivalent dose for passively-scattered proton radiotherapy and validation with measurements.

    PubMed

    Schneider, Christopher; Newhauser, Wayne; Farah, Jad

    2015-05-18

    Exposure to stray neutrons increases the risk of second cancer development after proton therapy. Previously reported analytical models of this exposure were difficult to configure and had not been investigated below 100 MeV proton energy. The purposes of this study were to test an analytical model of neutron equivalent dose per therapeutic absorbed dose  at 75 MeV and to improve the model by reducing the number of configuration parameters and making it continuous in proton energy from 100 to 250 MeV. To develop the analytical model, we used previously published H/D values in water from Monte Carlo simulations of a general-purpose beamline for proton energies from 100 to 250 MeV. We also configured and tested the model on in-air neutron equivalent doses measured for a 75 MeV ocular beamline. Predicted H/D values from the analytical model and Monte Carlo agreed well from 100 to 250 MeV (10% average difference). Predicted H/D values from the analytical model also agreed well with measurements at 75 MeV (15% average difference). The results indicate that analytical models can give fast, reliable calculations of neutron exposure after proton therapy. This ability is absent in treatment planning systems but vital to second cancer risk estimation.

  17. MR-guided breast radiotherapy: feasibility and magnetic-field impact on skin dose

    NASA Astrophysics Data System (ADS)

    van Heijst, Tristan C. F.; den Hartogh, Mariska D.; Lagendijk, Jan J. W.; Desirée van den Bongard, H. J. G.; van Asselen, Bram

    2013-09-01

    The UMC Utrecht MRI/linac (MRL) design provides image guidance with high soft-tissue contrast, directly during radiotherapy (RT). Breast cancer patients are a potential group to benefit from better guidance in the MRL. However, due to the electron return effect, the skin dose can be increased in presence of a magnetic field. Since large skin areas are generally involved in breast RT, the purpose of this study is to investigate the effects on the skin dose, for whole-breast irradiation (WBI) and accelerated partial-breast irradiation (APBI). In ten patients with early-stage breast cancer, targets and organs at risk (OARs) were delineated on postoperative CT scans co-registered with MRI. The OARs included the skin, comprising the first 5 mm of ipsilateral-breast tissue, plus extensions. Three intensity-modulated RT techniques were considered (2× WBI, 1× APBI). Individual beam geometries were used for all patients. Specially developed MRL treatment-planning software was used. Acceptable plans were generated for 0 T, 0.35 T and 1.5 T, using a class solution. The skin dose was augmented in WBI in the presence of a magnetic field, which is a potential drawback, whereas in APBI the induced effects were negligible. This opens possibilities for developing MR-guided partial-breast treatments in the MRL.

  18. Arsenic in drinking water and skin lesions: dose-response data from West Bengal, India.

    PubMed

    Haque, Reina; Mazumder, D N Guha; Samanta, Sambit; Ghosh, Nilima; Kalman, David; Smith, Meera M; Mitra, Soma; Santra, Amal; Lahiri, Sarbari; Das, Subhankar; De, Binay K; Smith, Allan H

    2003-03-01

    Over 6 million people live in areas of West Bengal, India, where groundwater sources are contaminated with naturally occurring arsenic. The key objective of this nested case-control study was to characterize the dose-response relation between low arsenic concentrations in drinking water and arsenic-induced skin keratoses and hyperpigmentation. We selected cases (persons with arsenic-induced skin lesions) and age- and sex-matched controls from participants in a 1995-1996 cross-sectional survey in West Bengal. We used a detailed assessment of arsenic exposure that covered at least 20 years. Participants were reexamined between 1998 and 2000. Consensus agreement by four physicians reviewing the skin lesion photographs confirmed the diagnosis in 87% of cases clinically diagnosed in the field. The average peak arsenic concentration in drinking water was 325 microg/liter for cases and 180 microg/liter for controls. The average latency for skin lesions was 23 years from first exposure. We found strong dose-response gradients with both peak and average arsenic water concentrations. The lowest peak arsenic ingested by a confirmed case was 115 microg/liter. Confirmation of case diagnosis and intensive longitudinal exposure assessment provide the basis for a detailed dose-response evaluation of arsenic-caused skin lesions.

  19. Photoneutron depth dose equivalent distributions in high-energy X-ray medical accelerators by a novel position-sensitive dosimeter.

    PubMed

    Hakimi, Amir; Sohrabi, Mehdi

    2017-04-01

    The purpose of this study was to; (1) investigate employing a novel position-sensitive mega-size polycarbonate (MSPC) dosimeter for photoneutron (PN) depth, profile and dose equivalent distributions studies in a multilayer polyethylene phantom in a Siemens ONCOR accelerator, and (2) develop depth dose equivalent distribution matrix data at different depths and positions of the phantom for patient PN dose equivalent determination and in particular for PN secondary cancer risk estimation. Position-sensitive MSPC dosimeters were successfully exposed at 9 different depths of the phantom in a 10×10cm(2) X-ray field. The dosimeters were processed in mega-size electrochemical chambers at optimum conditions. Each MSPC dosimeter was placed at a known phantom depth for PN depth dose equivalents and profiles on transverse, longitudinal and diagonal axes and isodose equivalent distribution studies in and out of the X-ray beam. PN dose equivalent distributions at any depth showed the highest value at the beam central axis and decreases as the distance increases. PN dose equivalent at any position studied in the axes has a maximum value on the phantom surface which decreases as depth increases due to flux reduction by multi-elastic scattering interactions. Extensive PN dose equivalent matrix data at different depths and positions in the phantom were determined. The position-sensitive MSPC dosimeters proved to be highly efficient for PN depth, profile and isodose equivalent distribution studies. The extensive data obtained highly assists for determining PN dose equivalent of a patient undergoing high-energy X-ray therapy and for PN secondary cancer risk estimation. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  20. Dosimetric advantages of generalised equivalent uniform dose-based optimisation on dose-volume objectives in intensity-modulated radiotherapy planning for bilateral breast cancer.

    PubMed

    Lee, T-F; Ting, H-M; Chao, P-J; Wang, H-Y; Shieh, C-S; Horng, M-F; Wu, J-M; Yeh, S-A; Cho, M-Y; Huang, E-Y; Huang, Y-J; Chen, H-C; Fang, F-M

    2012-11-01

    We compared and evaluated the differences between two models for treating bilateral breast cancer (BBC): (i) dose-volume-based intensity-modulated radiation treatment (DV plan), and (ii) dose-volume-based intensity-modulated radiotherapy with generalised equivalent uniform dose-based optimisation (DV-gEUD plan). The quality and performance of the DV plan and DV-gEUD plan using the Pinnacle(3) system (Philips, Fitchburg, WI) were evaluated and compared in 10 patients with stage T2-T4 BBC. The plans were delivered on a Varian 21EX linear accelerator (Varian Medical Systems, Milpitas, CA) equipped with a Millennium 120 leaf multileaf collimator (Varian Medical Systems). The parameters analysed included the conformity index, homogeneity index, tumour control probability of the planning target volume (PTV), the volumes V(20 Gy) and V(30 Gy) of the organs at risk (OAR, including the heart and lungs), mean dose and the normal tissue complication probability. Both plans met the requirements for the coverage of PTV with similar conformity and homogeneity indices. However, the DV-gEUD plan had the advantage of dose sparing for OAR: the mean doses of the heart and lungs, lung V(20) (Gy), and heart V(30) (Gy) in the DV-gEUD plan were lower than those in the DV plan (p<0.05). A better result can be obtained by starting with a DV-generated plan and then improving it by adding gEUD-based improvements to reduce the number of iterations and to improve the optimum dose distribution. Advances to knowledge The DV-gEUD plan provided superior dosimetric results for treating BBC in terms of PTV coverage and OAR sparing than the DV plan, without sacrificing the homogeneity of dose distribution in the PTV.

  1. A reappraisal of the reported dose equivalents at the boundary of the University of California Radiation Laboratory during the early days of Bevatron operation.

    PubMed

    Donahue, R J; Smith, A R; Thomas, R H; Zeman, G H

    2002-01-01

    The Bevatron of the Lawrence Berkeley National Laboratory operated with no permanent shielding-roof from 1954 to 1962. Neutron fluences measured at the laboratory perimeter reached a maximum in 1959, and were reported as an annual dose equivalent of 8.1 mSv (54% of the then operative radiation limit). The addition of temporary local shielding and improved operational techniques subsequently led to a steady decline in dose equivalent at the laboratory perimeter. A permanent concrete shielding-roof was constructed in 1962. In those early years of operation the reported dose equivalent, H, was derived from a measured total neutron fluence, phi, and an estimated spectrum-weighted fluence to dose equivalent conversion coefficient, (g), where H= (g) phi. The uncertainty in H was almost entirely due to the uncertainty in (g). While the measurements of phi were accurate the estimates of (g) were quite crude and depended upon measurements of average neutron energy, on assumptions about the shape of the neutron energy spectrum, and primitive values of fluence to dose equivalent conversion coefficients for monoenergetic neutrons. These early reported dose equivalents were known to be overestimated. This paper has reappraised the dose equivalents in the light of better information now available. Environmental neutron spectra have been calculated which more accurately correspond to the operational conditions of the Bevatron in the 1950s and early 1960s. than did those spectra available at that time. A new fluence to dose equivalent conversion function based on the latest data and for isotropic irradiation geometry was developed. From these two parameters better estimates of the coefficient (g) were determined and compared with the earlier values. From this reappraisal it is shown that the early reported dose equivalents were conservative by a factor of at least five.

  2. Toward a Molecular Equivalent Dose: Use of the Medaka Model in Comparative Risk Assessment.

    EPA Science Inventory

    Recent challenges in risk assessment underscore the need to compare the results of toxicity and dose-response testing among a growing list of animal models and, possibly, an array of in vitro screening assays. Assays that quantify types of DNA damage that are directly relevant to...

  3. Toward a Molecular Equivalent Dose: Use of the Medaka Model in Comparative Risk Assessment.

    EPA Science Inventory

    Recent challenges in risk assessment underscore the need to compare the results of toxicity and dose-response testing among a growing list of animal models and, possibly, an array of in vitro screening assays. Assays that quantify types of DNA damage that are directly relevant to...

  4. Toward a molecular equivalent dose: use of the medaka model in comparative risk assessment

    EPA Science Inventory

    Recent challenges in risk assessment underscore the need to compare the results of toxicity and dose-response testing among a growing list of animal models and, possibly, an array of in vitro screening assays. Assays that quantify types of DNA damage that are directly relevant to...

  5. Toward a molecular equivalent dose: use of the medaka model in comparative risk assessment

    EPA Science Inventory

    Recent challenges in risk assessment underscore the need to compare the results of toxicity and dose-response testing among a growing list of animal models and, possibly, an array of in vitro screening assays. Assays that quantify types of DNA damage that are directly relevant to...

  6. The cyclophosphamide equivalent dose as an approach for quantifying alkylating agent exposure: a report from the Childhood Cancer Survivor Study.

    PubMed

    Green, Daniel M; Nolan, Vikki G; Goodman, Pamela J; Whitton, John A; Srivastava, DeoKumar; Leisenring, Wendy M; Neglia, Joseph P; Sklar, Charles A; Kaste, Sue C; Hudson, Melissa M; Diller, Lisa R; Stovall, Marilyn; Donaldson, Sarah S; Robison, Leslie L

    2014-01-01

    Estimation of the risk of adverse long-term outcomes such as second malignant neoplasms and infertility often requires reproducible quantification of exposures. The method for quantification should be easily utilized and valid across different study populations. The widely used Alkylating Agent Dose (AAD) score is derived from the drug dose distribution of the study population and thus cannot be used for comparisons across populations as each will have a unique distribution of drug doses. We compared the performance of the Cyclophosphamide Equivalent Dose (CED), a unit for quantifying alkylating agent exposure independent of study population, to the AAD. Comparisons included associations from three Childhood Cancer Survivor Study (CCSS) outcome analyses, receiver operator characteristic (ROC) curves and goodness of fit based on the Akaike's Information Criterion (AIC). The CED and AAD performed essentially identically in analyses of risk for pregnancy among the partners of male CCSS participants, risk for adverse dental outcomes among all CCSS participants and risk for premature menopause among female CCSS participants, based on similar associations, lack of statistically significant differences between the areas under the ROC curves and similar model fit values for the AIC between models including the two measures of exposure. The CED is easily calculated, facilitating its use for patient counseling. It is independent of the drug dose distribution of a particular patient population, a characteristic that will allow direct comparisons of outcomes among epidemiological cohorts. We recommend the use of the CED in future research assessing cumulative alkylating agent exposure. © 2013 Wiley Periodicals, Inc.

  7. Personal dose equivalent conversion coefficients for neutron fluence over the energy range of 20-250 MeV.

    PubMed

    Olsher, R H; McLean, T D; Justus, A L; Devine, R T; Gadd, M S

    2010-03-01

    Monte Carlo simulations were performed to extend existing neutron personal dose equivalent fluence-to-dose conversion coefficients to an energy of 250 MeV. Presently, conversion coefficients, H(p,slab)(10,alpha)/Phi, are given by ICRP-74 and ICRU-57 for a range of angles of radiation incidence (alpha = 0, 15, 30, 45, 60 and 75 degrees ) in the energy range from thermal to 20 MeV. Standard practice has been to base operational dose quantity calculations <20 MeV on the kerma approximation, which assumes that charged particle secondaries are locally deposited, or at least that charged particle equilibrium exists within the tally cell volume. However, with increasing neutron energy the kerma approximation may no longer be valid for some energetic secondaries such as protons. The Los Alamos Monte Carlo radiation transport code MCNPX was used for all absorbed dose calculations. Transport models and collision-based energy deposition tallies were used for neutron energies >20 MeV. Both light and heavy ions (HIs) (carbon, nitrogen and oxygen recoil nuclei) were transported down to a lower energy limit (1 keV for light ions and 5 MeV for HIs). Track energy below the limit was assumed to be locally deposited. For neutron tracks <20 MeV, kerma factors were used to obtain absorbed dose. Results are presented for a discrete set of angles of incidence on an ICRU tissue slab phantom.

  8. Comparison of dose calculation algorithms in phantoms with lung equivalent heterogeneities under conditions of lateral electronic disequilibrium

    SciTech Connect

    Carrasco, P.; Jornet, N.; Duch, M.A.; Weber, L.; Ginjaume, M.; Eudaldo, T.; Jurado, D.; Ruiz, A.; Ribas, M.

    2004-10-01

    An extensive set of benchmark measurement of PDDs and beam profiles was performed in a heterogeneous layer phantom, including a lung equivalent heterogeneity, by means of several detectors and compared against the predicted dose values by different calculation algorithms in two treatment planning systems. PDDs were measured with TLDs, plane parallel and cylindrical ionization chambers and beam profiles with films. Additionally, Monte Carlo simulations by meansof the PENELOPE code were performed. Four different field sizes (10x10, 5x5, 2x2, and1x1 cm{sup 2}) and two lung equivalent materials (CIRS, {rho}{sub e}{sup w}=0.195 and St. Bartholomew Hospital, London, {rho}{sub e}{sup w}=0.244-0.322) were studied. The performance of four correction-based algorithms and one based on convolution-superposition was analyzed. The correction-based algorithms were the Batho, the Modified Batho, and the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system and the TMS Pencil Beam from the Helax-TMS (Nucletron) treatment planning system. The convolution-superposition algorithm was the Collapsed Cone implemented in the Helax-TMS. The only studied calculation methods that correlated successfully with the measured values with a 2% average inside all media were the Collapsed Cone and the Monte Carlo simulation. The biggest difference between the predicted and the delivered dose in the beam axis was found for the EqTAR algorithm inside the CIRS lung equivalent material in a 2x2 cm{sup 2} 18 MV x-ray beam. In these conditions, average and maximum difference against the TLD measurements were 32% and 39%, respectively. In the water equivalent part of the phantom every algorithm correctly predicted the dose (within 2%) everywhere except very close to the interfaces where differences up to 24% were found for 2x2 cm{sup 2} 18 MV photon beams. Consistent values were found between the reference detector (ionization chamber in water and TLD in lung) and Monte Carlo

  9. Comparison of dose calculation algorithms in phantoms with lung equivalent heterogeneities under conditions of lateral electronic disequilibrium.

    PubMed

    Carrasco, P; Jornet, N; Duch, M A; Weber, L; Ginjaume, M; Eudaldo, T; Jurado, D; Ruiz, A; Ribas, M

    2004-10-01

    An extensive set of benchmark measurement of PDDs and beam profiles was performed in a heterogeneous layer phantom, including a lung equivalent heterogeneity, by means of several detectors and compared against the predicted dose values by different calculation algorithms in two treatment planning systems. PDDs were measured with TLDs, plane parallel and cylindrical ionization chambers and beam profiles with films. Additionally, Monte Carlo simulations by means of the PENELOPE code were performed. Four different field sizes (10 x 10, 5 x 5, 2 x 2, and 1 x 1 cm2) and two lung equivalent materials (CIRS, p(w)e=0.195 and St. Bartholomew Hospital, London, p(w)e=0.244-0.322) were studied. The performance of four correction-based algorithms and one based on convolution-superposition was analyzed. The correction-based algorithms were the Batho, the Modified Batho, and the Equivalent TAR implemented in the Cadplan (Varian) treatment planning system and the TMS Pencil Beam from the Helax-TMS (Nucletron) treatment planning system. The convolution-superposition algorithm was the Collapsed Cone implemented in the Helax-TMS. The only studied calculation methods that correlated successfully with the measured values with a 2% average inside all media were the Collapsed Cone and the Monte Carlo simulation. The biggest difference between the predicted and the delivered dose in the beam axis was found for the EqTAR algorithm inside the CIRS lung equivalent material in a 2 x 2 cm2 18 MV x-ray beam. In these conditions, average and maximum difference against the TLD measurements were 32% and 39%, respectively. In the water equivalent part of the phantom every algorithm correctly predicted the dose (within 2%) everywhere except very close to the interfaces where differences up to 24% were found for 2 x 2 cm2 18 MV photon beams. Consistent values were found between the reference detector (ionization chamber in water and TLD in lung) and Monte Carlo simulations, yielding minimal

  10. Using two detectors concurrently to monitor ambient dose equivalent rates in vehicle surveys of radiocesium contaminated land.

    PubMed

    Takeishi, Minoru; Shibamichi, Masaru; Malins, Alex; Kurikami, Hiroshi; Murakami, Mitsuhiro; Saegusa, Jun; Yoneya, Masayuki

    2017-10-01

    In response to the accident at Tokyo Electric Power Company's Fukushima Dai-ichi Nuclear Power Plant (FDNPP), vehicle-borne monitoring was used to map radiation levels for radiological protection of the public. By convention measurements from vehicle-borne surveys are converted to the ambient dose equivalent rate at 1 m height in the absence of the vehicle. This allows for comparison with results from other types of survey, including surveys with hand-held or airborne instruments. To improve the accuracy of the converted results from vehicle-borne surveys, we investigated combining measurements from two detectors mounted on the vehicle at different heights above the ground. A dual-detector setup was added to a JAEA monitoring car and compared against hand-held survey meter measurements in Fukushima Prefecture. The results obtained by combining measurements from two detectors were within ±20% of the hand-held reference measurements. The mean absolute percentage deviation from the reference measurements was 7.2%. The combined results from the two detectors were more accurate than those from either the roof-mounted detector, or the detector inside the vehicle, taken alone. One issue with vehicle-borne surveys is that ambient dose equivalent rates above roads are not necessarily representative of adjacent areas. This is because radiocesium is often deficient on asphalt surfaces, as it is easily scrubbed off by rain, wind and vehicle tires. To tackle this issue, we investigated mounting heights for vehicle-borne detectors using Monte Carlo gamma-ray simulations. When radiocesium is deficient on a road compared to the adjacent land, mounting detectors high on vehicles yields results closer to the values adjacent to the road. The ratio of ambient dose equivalent rates reported by detectors mounted at different heights in a dual-detector setup indicates whether radiocesium is deficient on the road compared to the adjacent land. Copyright © 2017 Elsevier Ltd. All rights

  11. Does digital acquisition reduce patients' skin dose in cardiac interventional procedures? An experimental study.

    PubMed

    Chida, Koichi; Saito, Haruo; Zuguchi, Masayuki; Shirotori, Kazutoshi; Kumagai, Shinsaku; Nakayama, Hiromi; Matsubara, Kana; Kohzuki, Masahiro

    2004-10-01

    It is necessary to reduce the exposure doses from both fluoroscopy and angiocardiography. Pulsed fluoroscopy clearly reduces patients' exposure. By contrast, whether digital acquisition reduces patients' exposure is not clear. This study simulated the skin radiation doses of patients in cardiac catheterization laboratories with various radiography systems used in percutaneous transluminal coronary angioplasty to determine whether digital acquisition reduces patient exposure as compared with cine film recording. The entrance surface doses with cineangiography and fluoroscopy of acrylic phantoms were compared for 11 radiography systems at seven facilities; each performs more than 100 cardiac intervention procedures per year. The entrance surface dose for an acrylic plate (20 cm thick) was measured using a skin-dose monitor. The maximum dose exceeded the minimum dose by 6.44 times for cineangiography and by 3.42 times for fluoroscopy. The entrance surface dose with acrylic plate was lower with digital-only acquisition (mean +/- SD, 3.07 +/- 0.84 mGy/sec) than with film recording (6.00 +/- 3.04 mGy/sec). By contrast, the entrance surface frame dose, after correction for the cine frame rate, tended to be higher with digital acquisition than with film recording (0.210 +/- 0.053 vs 0.179 +/- 0.058 mGy/frame, respectively). CONCLUSION. The entrance surface dose was approximately 50% less with digital-only acquisition than with film recording. However, after correcting the dose for cine frame rate, filmless acquisition did not in itself reduce the exposure. For the surface dose to be reduced for cardiac interventional radiography, even with digital filmless radiography systems, a low recording speed is necessary for angiocardiography.

  12. Degradation of proton depth dose distributions attributable to microstructures in lung-equivalent material

    SciTech Connect

    Titt, Uwe Mirkovic, Dragan; Mohan, Radhe; Sell, Martin; Unkelbach, Jan; Bangert, Mark; Oelfke, Uwe

    2015-11-15

    Purpose: The purpose of the work reported here was to investigate the influence of sub-millimeter size heterogeneities on the degradation of the distal edges of proton beams and to validate Monte Carlo (MC) methods’ ability to correctly predict such degradation. Methods: A custom-designed high-resolution plastic phantom approximating highly heterogeneous, lung-like structures was employed in measurements and in Monte Carlo simulations to evaluate the degradation of proton Bragg curves penetrating heterogeneous media. Results: Significant differences in distal falloff widths and in peak dose values were observed in the measured and the Monte Carlo simulated curves compared to pristine proton Bragg curves. Furthermore, differences between simulations of beams penetrating CT images of the phantom did not agree well with the corresponding experimental differences. The distal falloff widths in CT image-based geometries were underestimated by up to 0.2 cm in water (corresponding to 0.8–1.4 cm in lung tissue), and the peak dose values of pristine proton beams were overestimated by as much as ~35% compared to measured curves or depth-dose curves simulated on the basis of true geometry. The authors demonstrate that these discrepancies were caused by the limited spatial resolution of CT images that served as a basis for dose calculations and lead to underestimation of the impact of the fine structure of tissue heterogeneities. A convolution model was successfully applied to mitigate the underestimation. Conclusions: The results of this study justify further development of models to better represent heterogeneity effects in soft-tissue geometries, such as lung, and to correct systematic underestimation of the degradation of the distal edge of proton doses.

  13. Degradation of proton depth dose distributions attributable to microstructures in lung-equivalent material

    PubMed Central

    Titt, Uwe; Sell, Martin; Unkelbach, Jan; Bangert, Mark; Mirkovic, Dragan; Oelfke, Uwe; Mohan, Radhe

    2015-01-01

    Purpose: The purpose of the work reported here was to investigate the influence of sub-millimeter size heterogeneities on the degradation of the distal edges of proton beams and to validate Monte Carlo (MC) methods’ ability to correctly predict such degradation. Methods: A custom-designed high-resolution plastic phantom approximating highly heterogeneous, lung-like structures was employed in measurements and in Monte Carlo simulations to evaluate the degradation of proton Bragg curves penetrating heterogeneous media. Results: Significant differences in distal falloff widths and in peak dose values were observed in the measured and the Monte Carlo simulated curves compared to pristine proton Bragg curves. Furthermore, differences between simulations of beams penetrating CT images of the phantom did not agree well with the corresponding experimental differences. The distal falloff widths in CT image-based geometries were underestimated by up to 0.2 cm in water (corresponding to 0.8–1.4 cm in lung tissue), and the peak dose values of pristine proton beams were overestimated by as much as ˜35% compared to measured curves or depth-dose curves simulated on the basis of true geometry. The authors demonstrate that these discrepancies were caused by the limited spatial resolution of CT images that served as a basis for dose calculations and lead to underestimation of the impact of the fine structure of tissue heterogeneities. A convolution model was successfully applied to mitigate the underestimation. Conclusions: The results of this study justify further development of models to better represent heterogeneity effects in soft-tissue geometries, such as lung, and to correct systematic underestimation of the degradation of the distal edge of proton doses. PMID:26520732

  14. A four-organ-chip for interconnected long-term co-culture of human intestine, liver, skin and kidney equivalents.

    PubMed

    Maschmeyer, Ilka; Lorenz, Alexandra K; Schimek, Katharina; Hasenberg, Tobias; Ramme, Anja P; Hübner, Juliane; Lindner, Marcus; Drewell, Christopher; Bauer, Sophie; Thomas, Alexander; Sambo, Naomia Sisoli; Sonntag, Frank; Lauster, Roland; Marx, Uwe

    2015-06-21

    Systemic absorption and metabolism of drugs in the small intestine, metabolism by the liver as well as excretion by the kidney are key determinants of efficacy and safety for therapeutic candidates. However, these systemic responses of applied substances lack in most in vitro assays. In this study, a microphysiological system maintaining the functionality of four organs over 28 days in co-culture has been established at a minute but standardized microsystem scale. Preformed human intestine and skin models have been integrated into the four-organ-chip on standard cell culture inserts at a size 100,000-fold smaller than their human counterpart organs. A 3D-based spheroid, equivalent to ten liver lobules, mimics liver function. Finally, a barrier segregating the media flow through the organs from fluids excreted by the kidney has been generated by a polymeric membrane covered by a monolayer of human proximal tubule epithelial cells. A peristaltic on-chip micropump ensures pulsatile media flow interconnecting the four tissue culture compartments through microfluidic channels. A second microfluidic circuit ensures drainage of the fluid excreted through the kidney epithelial cell layer. This four-organ-chip system assures near to physiological fluid-to-tissue ratios. In-depth metabolic and gene analysis revealed the establishment of reproducible homeostasis among the co-cultures within two to four days, sustainable over at least 28 days independent of the individual human cell line or tissue donor background used for each organ equivalent. Lastly, 3D imaging two-photon microscopy visualised details of spatiotemporal segregation of the two microfluidic flows by proximal tubule epithelia. To our knowledge, this study is the first approach to establish a system for in vitro microfluidic ADME profiling and repeated dose systemic toxicity testing of drug candidates over 28 days.

  15. Increased Skin Dose With the Use of a Custom Mattress for Prone Breast Radiotherapy

    SciTech Connect

    Becker, Stewart J. Patel, Rakesh R.; Mackie, Thomas R.

    2007-10-01

    The purpose of this study was to measure and compare the loss of buildup to the skin of the breast in the prone position due to 2 different positioning systems during tangential external beam irradiation. Two experiments were performed; one with a standard nylon-covered foam support and another with a novel helium-filled Mylar bag support. The choice of helium-filled Mylar was to reduce the contamination to as low as possible. The experiments were designed to allow a surface dose measurement and a depth dose profile with the pads placed in the path of the beam in front of the detector. All measurements were taken using a Capintec PS-033 thin-window parallel plate ionization chamber. The standard nylon-covered foam pad caused the surface dose to rise as it got closer to the skin. When the pad was directly touching the surface, the surface dose increased by 300% compared to the result when no pad was present. This loss of buildup to the surface was similar to that of a custom bolus material. The opposite effect occurred with the use of the helium-filled Mylar bag, namely the surface dose gradually decreased as the pad got closer to the phantom. When the Mylar pad was directly touching the phantom, the surface dose was decreased by 7% compared to when no pad was present. The use of a foam pad could potentially result in a significant higher dose to the skin, resulting in an enhanced acute skin reaction. Therefore, special care should be taken in this clinical scenario and further investigation of an air- or helium-based mylar support pad should be investigated in the context of definitive breast radiation treatment.

  16. Structural changes of skin and amnion grafts for transplantation purposes following different doses of irradiation.

    PubMed

    Mrázová, H; Koller, J; Fujeríková, G; Babál, P

    2014-09-01

    An important part of the preparation of biological material for transplantation is sterilization. The aim of our study was to assess the impact of ionizing radiation on three types of biological tissues and the impact of different doses on cells and extracellular matrix. Three types of frozen tissues (porcine skin xenografts, human skin allografts and human amnion) were divided into five groups, control and groups according to the dose of radiation to which these samples were exposed (12.5, 25, 35 and 50 kGy). The tissue samples were fixed by formalin, processed by routine paraffin technique and stained with hematoxylin and eosin, alcian blue at pH 2.5, orcein, periodic acid schiff reaction and silver impregnation. The staining with hematoxylin and eosin showed hydropic degeneration of the cells of epidermis in xenografts by the dose of 12.5 kGy, in human skin it was observed by the dose of 35 kGy. The staining for elastic fibers revealed damage of fine elastic fibers in the xenografts dermis by the dose of 12.5 kGy, in the allografts by 35 kGy. Another change was the disintegration of basement membrane of epithelium, especially in the human amnion at the dose of 50 kGy. The silver impregnation visualized nuclear chromatin condensation mainly in human amnion at the dose of 12.5 kGy. Our results have shown that the porcine xenografts and human amnion were more sensitive to irradiation than the human skin. In the next phase of the project we will focus at more detailed changes in the tissues using immunohistochemical techniques.

  17. Preliminary On-Orbit Neutron Dose Equivalent and Energy Spectrum Results from the ISS-RAD Fast Neutron Detector (FND)

    NASA Technical Reports Server (NTRS)

    Semones, Edward; Leitgab, Martin

    2016-01-01

    The ISS-RAD instrument was activated on ISS on February 1st, 2016. Integrated in ISS-RAD, the Fast Neutron Detector (FND) performs, for the first time on ISS, routine and precise direct neutron measurements between 0.5 and 8 MeV. Preliminary results for neutron dose equivalent and neutron flux energy distributions from online/on-board algorithms and offline ground analyses will be shown, along with comparisons to simulated data and previously measured neutron spectral data. On-orbit data quality and pre-launch analysis validation results will be discussed as well.

  18. Evaluation of dose equivalent by the electronic personal dosemeter for neutron 'Saphydose-N' at different workplaces of nuclear facilities.

    PubMed

    Chau, Q; Lahaye, T

    2007-01-01

    This paper presents the results of measurements made with the electronic personal neutron Saphydose-N during the four campaigns of the European contract EVIDOS (EValuation of Individual DOSimetry in mixed neutron and photon radiation fields). These measurements were performed at Institute for Radiological Protection and Nuclear Safety (IRSN) in France (C0), at the Krümmel Nuclear Power Plant in Germany (C1), at the VENUS Research Reactor and the Belgonucléaire fuel processing plant in Belgium (C2) and at the Ringhals Nuclear Power Plant in Sweden (C3). The results for Saphydose-N are compared with reference values for dose equivalent.

  19. Skin equivalent tissue-engineered construct: co-cultured fibroblasts/ keratinocytes on 3D matrices of sericin hope cocoons.

    PubMed

    Nayak, Sunita; Dey, Sancharika; Kundu, Subhas C

    2013-01-01

    The development of effective and alternative tissue-engineered skin replacements to autografts, allografts and xenografts has became a clinical requirement due to the problems related to source of donor tissue and the perceived risk of disease transmission. In the present study 3D tissue engineered construct of sericin is developed using co-culture of keratinocytes on the upper surface of the fabricated matrices and with fibroblasts on lower surface. Sericin is obtained from "Sericin Hope" silkworm of Bombyx mori mutant and is extracted from cocoons by autoclave. Porous sericin matrices are prepared by freeze dried method using genipin as crosslinker. The matrices are characterized biochemically and biophysically. The cell proliferation and viability of co-cultured fibroblasts and keratinocytes on matrices for at least 28 days are observed by live/dead assay, Alamar blue assay, and by dual fluorescent staining. The growth of the fibroblasts and keratinocytes in co-culture is correlated with the expression level of TGF-β, b-FGF and IL-8 in the cultured supernatants by enzyme-linked immunosorbent assay. The histological analysis further demonstrates a multi-layered stratified epidermal layer of uninhibited keratinocytes in co-cultured constructs. Presence of involucrin, collagen IV and the fibroblast surface protein in immuno-histochemical stained sections of co-cultured matrices indicates the significance of paracrine signaling between keratinocytes and fibroblasts in the expression of extracellular matrix protein for dermal repair. No significant amount of pro inflammatory cytokines (TNF-α, IL-1β and nitric oxide) production are evidenced when macrophages grown on the sericin matrices. The results all together depict the potentiality of sericin 3D matrices as skin equivalent tissue engineered construct in wound repair.

  20. Skin Equivalent Tissue-Engineered Construct: Co-Cultured Fibroblasts/ Keratinocytes on 3D Matrices of Sericin Hope Cocoons

    PubMed Central

    Nayak, Sunita; Dey, Sancharika; Kundu, Subhas C.

    2013-01-01

    The development of effective and alternative tissue-engineered skin replacements to autografts, allografts and xenografts has became a clinical requirement due to the problems related to source of donor tissue and the perceived risk of disease transmission. In the present study 3D tissue engineered construct of sericin is developed using co-culture of keratinocytes on the upper surface of the fabricated matrices and with fibroblasts on lower surface. Sericin is obtained from “Sericin Hope” silkworm of Bombyx mori mutant and is extracted from cocoons by autoclave. Porous sericin matrices are prepared by freeze dried method using genipin as crosslinker. The matrices are characterized biochemically and biophysically. The cell proliferation and viability of co-cultured fibroblasts and keratinocytes on matrices for at least 28 days are observed by live/dead assay, Alamar blue assay, and by dual fluorescent staining. The growth of the fibroblasts and keratinocytes in co-culture is correlated with the expression level of TGF-β, b-FGF and IL-8 in the cultured supernatants by enzyme-linked immunosorbent assay. The histological analysis further demonstrates a multi-layered stratified epidermal layer of uninhibited keratinocytes in co-cultured constructs. Presence of involucrin, collagen IV and the fibroblast surface protein in immuno-histochemical stained sections of co-cultured matrices indicates the significance of paracrine signaling between keratinocytes and fibroblasts in the expression of extracellular matrix protein for dermal repair. No significant amount of pro inflammatory cytokines (TNF-α, IL-1β and nitric oxide) production are evidenced when macrophages grown on the sericin matrices. The results all together depict the potentiality of sericin 3D matrices as skin equivalent tissue engineered construct in wound repair. PMID:24058626

  1. Assessment of the in vitro dermal irritation potential of cerium, silver, and titanium nanoparticles in a human skin equivalent model.

    PubMed

    Miyani, Vivek A; Hughes, Michael F

    2017-06-01

    Metal nanoparticles can potentially contact human skin during their manufacture and use in commercial products. This study examined the potential of metal nanoparticles to elicit irritant contact dermatitis in a human skin equivalent model (HSEM) derived from keratinocytes. Ag (10-100 nm), TiO2 (22-214 nm), and CeO2 (15-40 nm) nanoparticles were studied. The Ag particles were either coated/shelled with silica or capped with citrate or polyvinylpyrrolidone and were in water. The TiO2 and CeO2 particles were suspended in media containing 10% fetal bovine serum. The particles (1 mg/ml) were applied to the epidermal surface of the HSEM. Positive (5% sodium dodecyl sulfate (SDS)) and negative controls (saline or media) were included. After 1-h exposure at 37 °C, the HSEM was washed with saline to remove the nanoparticles. Following a 42-h incubation (37 °C), HSEM viability was assessed using the MTT assay. A test substance is considered a dermal irritant if the HSEM viability is < 50%. The mean viability for the SDS-treated HSEM was 7.8%. The viabilities of the nanoparticle-treated HSEM were 91% or greater. The Ag, TiO2, and CeO2 nanoparticles examined were not dermal irritants under the conditions used in this study. The stratum corneum of the HSEM may limit penetration of metal nanoparticles to induce toxicity.

  2. A Comparison of Skin and Chest Wall Dose Delivered With Multicatheter, Contura Multilumen Balloon, and MammoSite Breast Brachytherapy

    SciTech Connect

    Cuttino, Laurie W.; Todor, Dorin; Rosu, Mihaela; Arthur, Douglas W.

    2011-01-01

    Purpose: Skin and chest wall doses have been correlated with toxicity in patients treated with breast brachytherapy . This investigation compared the ability to control skin and chest wall doses between patients treated with multicatheter (MC), Contura multilumen balloon (CMLB), and MammoSite (MS) brachytherapy. Methods and Materials: 43 patients treated with the MC technique, 45 patients treated with the CMLB, and 83 patients treated with the MS were reviewed. The maximum doses delivered to the skin and chest wall were calculated for all patients. Results: The mean maximum skin doses for the MC, CMLB, and MS were 2.3 Gy (67% of prescription dose), 2.8 Gy (82% of prescription dose), and 3.2 Gy per fraction (94% of prescription dose), respectively. Although the skin distances were similar (p = 0.23) for the two balloon techniques, the mean skin dose with the CMLB was significantly lower than with the MS (p = 0.05). The mean maximum rib doses for the MC, CMLB, and MS were 2.3 Gy (67% of prescription dose), 2.8 Gy (82% of prescription dose), and 3.6 Gy per fraction (105% of prescription dose), respectively. Again, the mean rib dose with the CMLB was significantly lower than with the MS (p = 0.002). Conclusion: The MC and CMLB techniques are associated with significantly lower mean skin and rib doses than is the MS. Treatment with the MS was associated with significantly more patients receiving doses to the skin or rib in excess of 125% of the prescription. Treatment with the CMLB may prove to yield less normal tissue toxicity than treatment with the MS.

  3. Influence of Th2 Cytokines on the Cornified Envelope, Tight Junction Proteins, and ß-Defensins in Filaggrin-Deficient Skin Equivalents.

    PubMed

    Hönzke, Stefan; Wallmeyer, Leonie; Ostrowski, Anja; Radbruch, Moritz; Mundhenk, Lars; Schäfer-Korting, Monika; Hedtrich, Sarah

    2016-03-01

    Atopic dermatitis is a chronic skin condition with complex etiology. It is characterized by skin barrier defects and T helper type 2 (Th2)-polarized inflammation. Although mutations in the filaggrin gene are known to be prominent genetic risk factors for the development of atopic dermatitis, the interdependency between these and an altered cytokine milieu is not fully understood. In this study, we evaluated the direct effects of filaggrin deficiency on the cornified envelope, tight junction proteins, and innate immune response, and report the effects of Th2 cytokines in normal and filaggrin-deficient skin equivalents. Supplementation with IL-4 and IL-13 led to distinct histologic changes and significantly increased skin surface pH, both of which were enhanced in filaggrin knockdown skin equivalents. We detected a compensatory up-regulation of involucrin and occludin in filaggrin-deficient skin that was dramatically disturbed when simultaneous inflammation occurred. Furthermore, we found that a lack of filaggrin triggered an up-regulation of human ?-defensin 2 via an unknown mechanism, which was abolished by Th2 cytokine supplementation. Taken together, these results indicate that defects in the epidermal barrier, skin permeability, and cutaneous innate immune response are not primarily linked to filaggrin deficiency but are rather secondarily induced by Th2 inflammation.

  4. The minimal melanogenesis dose/minimal erythema dose ratio declines with increasing skin pigmentation using solar simulator and narrowband ultraviolet B exposure.

    PubMed

    Ravnbak, Mette H; Philipsen, Peter A; Wulf, Hans Christian

    2010-06-01

    To investigate the relation between pre-exposure skin pigmentation and the minimal melanogenesis dose (MMD)/minimal erythema dose (MED) ratio after a single narrowband ultraviolet B (nUVB) and solar simulator (Solar) exposure. In fair-skinned individuals, it is well known that the UV dose to give pigmentation (MMD) after a single exposure to UVB is larger than the UV dose to elicit erythema (MED) (MEDskinned individuals. Eighty-four volunteers with a wide variation in skin pigmentation (Fitzpatrick skin types I-V) were included. After a single Solar or nUVB exposure we found that the ratio MMD/MED depends on skin pigmentation. In light-pigmented individuals, up to 1.9 MED is required to induce pigmentation (MMD). The MMD/MED ratio is about 1.5 in medium-pigmented and dark-pigmented individuals. In very brown-pigmented individuals the MMD/MED ratio is 1 (MED=MMD). This connection was most pronounced for facultative skin at wintertime. The ratio was almost stable for constitutive pigmentation with MMD/MED=1.3. The ratios were almost independent of skin type. The ratio MMD/MED is highly dependent on skin pigmentation after a single exposure to Solar or nUVB and is independent of skin type.

  5. High and Low Doses of Ionizing Radiation Induce Different Secretome Profiles in a Human Skin Model

    SciTech Connect

    Zhang, Qibin; Matzke, Melissa M.; Schepmoes, Athena A.; Moore, Ronald J.; Webb-Robertson, Bobbie-Jo M.; Hu, Zeping; Monroe, Matthew E.; Qian, Weijun; Smith, Richard D.; Morgan, William F.

    2014-03-18

    It is postulated that secreted soluble factors are important contributors of bystander effect and adaptive responses observed in low dose ionizing radiation. Using multidimensional liquid chromatography-mass spectrometry based proteomics, we quantified the changes of skin tissue secretome – the proteins secreted from a full thickness, reconstituted 3-dimensional skin tissue model 48 hr after exposure to 3, 10 and 200 cGy of X-rays. Overall, 135 proteins showed statistical significant difference between the sham (0 cGy) and any of the irradiated groups (3, 10 or 200 cGy) on the basis of Dunnett adjusted t-test; among these, 97 proteins showed a trend of downregulation and 9 proteins showed a trend of upregulation with increasing radiation dose. In addition, there were 21 and 8 proteins observed to have irregular trends with the 10 cGy irradiated group either having the highest or the lowest level among all three radiated doses. Moreover, two proteins, carboxypeptidase E and ubiquitin carboxyl-terminal hydrolase isozyme L1 were sensitive to ionizing radiation, but relatively independent of radiation dose. Conversely, proteasome activator complex subunit 2 protein appeared to be sensitive to the dose of radiation, as rapid upregulation of this protein was observed when radiation doses were increased from 3, to 10 or 200 cGy. These results suggest that different mechanisms of action exist at the secretome level for low and high doses of ionizing radiation.

  6. Measured and Calculated Neutron Spectra and Dose Equivalent Rates at High Altitudes; Relevance to SST Operations and Space Research

    NASA Technical Reports Server (NTRS)

    Foelsche, T.; Mendell, R. B.; Wilson, J. W.; Adams, R. R.

    1974-01-01

    Results of the NASA Langley-New York University high-altitude radiation study are presented. Measurements of the absorbed dose rate and of secondary fast neutrons (1 to 10 MeV energy) during the years 1965 to 1971 are used to determine the maximum radiation exposure from galactic and solar cosmic rays of supersonic transport (SST) and subsonic jet occupants. The maximum dose equivalent rates that the SST crews might receive turn out to be 13 to 20 percent of the maximum permissible dose rate (MPD) for radiation workers (5 rem/yr). The exposure of passengers encountering an intense giant-energy solar particle event could exceed the MPD for the general population (0.5 rem/yr), but would be within these permissible limits if in such rare cases the transport descends to subsonic altitude; it is in general less than 12 percent of the MPD. By Monte Carlo calculations of the transport and buildup of nucleons in air for incident proton energies E of 0.02 to 10 GeV, the measured neutron spectra were extrapolated to lower and higher energies and for galactic cosmic rays were found to continue with a relatively high intensity to energies greater than 400 MeV, in a wide altitude range. This condition, together with the measured intensity profiles of fast neutrons, revealed that the biologically important fast and energetic neutrons penetrate deep into the atmosphere and contribute approximately 50 percent of the dose equivalant rates at SST and present subsonic jet altitudes.

  7. Prednisone dosing per body weight or body surface area in children with nephrotic syndrome: is it equivalent?

    PubMed

    Feber, Janusz; Al-Matrafi, Jamila; Farhadi, Elham; Vaillancourt, Régis; Wolfish, Norman

    2009-05-01

    The current guidelines recommend a dosage of prednisone of 60 mg/m(2) body surface area per day (BSA PRED) for the initial therapy of nephrotic syndrome (NS). Alternatively, a dosage of 2 mg/kg body weight per day (W PRED) can be used. We hypothesized that the BSA PRED and W PRED are not equivalent and analyzed the differences between BSA PRED calculated with various formulas for body surface area (BSA), W PRED and the dose of prednisone prescribed for our patients. We performed a retrospective chart review of the patients at their initial presentation of NS. Thirty-three children were included, of median age 3.34 years at presentation. The W PRED was significantly lower than BSA PRED (P < 0.05), with a median W PRED:BSA PRED ratio of 0.85 [interquartile range (IQR) 0.8 to 0.9]. The difference between W PRED and BSA PRED decreased proportionally to patients' weights up to 30 kg. No differences were noted between the various BSA formulas using both weight and height for the calculation of BSA. The Bland-Altman analysis showed a proportional error between W PRED and BSA PRED up to the average daily dose of 60 mg, with a mean bias of 0.86 (95% limits of agreement = 0.68 to 1.05). Ten out of the 33 patients (30%) were given a lower than recommended BSA PRED dose by more than 5 mg/day. In conclusion, the dosage of prednisone at 2 mg/kg per day versus 60 mg/m(2) per day is not equivalent for patients with weights <30 kg and/or dose <60 mg/day.

  8. Expression of proliferative and inflammatory markers in a full-thickness human skin equivalent following exposure to the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide

    SciTech Connect

    Black, Adrienne T.; Hayden, Patrick J.; Casillas, Robert P.; Heck, Diane E.; Gerecke, Donald R.; Sinko, Patrick J.; Laskin, Debra L.; Laskin, Jeffrey D.

    2010-12-01

    Sulfur mustard is a potent vesicant that induces inflammation, edema and blistering following dermal exposure. To assess molecular mechanisms mediating these responses, we analyzed the effects of the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide, on EpiDerm-FT{sup TM}, a commercially available full-thickness human skin equivalent. CEES (100-1000 {mu}M) caused a concentration-dependent increase in pyknotic nuclei and vacuolization in basal keratinocytes; at high concentrations (300-1000 {mu}M), CEES also disrupted keratin filament architecture in the stratum corneum. This was associated with time-dependent increases in expression of proliferating cell nuclear antigen, a marker of cell proliferation, and poly(ADP-ribose) polymerase (PARP) and phosphorylated histone H2AX, markers of DNA damage. Concentration- and time-dependent increases in mRNA and protein expression of eicosanoid biosynthetic enzymes including COX-2, 5-lipoxygenase, microsomal PGE{sub 2} synthases, leukotriene (LT) A{sub 4} hydrolase and LTC{sub 4} synthase were observed in CEES-treated skin equivalents, as well as in antioxidant enzymes, glutathione S-transferases A1-2 (GSTA1-2), GSTA3 and GSTA4. These data demonstrate that CEES induces rapid cellular damage, cytotoxicity and inflammation in full-thickness skin equivalents. These effects are similar to human responses to vesicants in vivo and suggest that the full thickness skin equivalent is a useful in vitro model to characterize the biological effects of mustards and to develop potential therapeutics.

  9. Expression of proliferative and inflammatory markers in a full-thickness human skin equivalent following exposure to the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide

    PubMed Central

    Black, Adrienne T.; Hayden, Patrick J.; Casillas, Robert P.; Heck, Diane E.; Gerecke, Donald R.; Sinko, Patrick J.; Laskin, Debra L.; Laskin, Jeffrey D.

    2010-01-01

    Sulfur mustard is a potent vesicant that induces inflammation, edema and blistering following dermal exposure. To assess molecular mechanisms mediating these responses, we analyzed the effects of the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide, on EpiDerm-FT™, a commercially available full-thickness human skin equivalent. CEES (100–1000 μM) caused a concentration-dependent increase in pyknotic nuclei and vacuolization in basal keratinocytes; at high concentrations (300–1000 μM), CEES also disrupted keratin filament architecture in the stratum corneum. This was associated with time-dependent increases in expression of proliferating cell nuclear antigen, a marker of cell proliferation, and poly(ADP-ribose) polymerase (PARP) and phosphorylated histone H2AX, markers of DNA damage. Concentration- and time-dependent increases in mRNA and protein expression of eicosanoid biosynthetic enzymes including COX-2, 5-lipoxygenase, microsomal PGE2 synthases, leukotriene (LT) A4 hydrolase and LTC4 synthase were observed in CEES-treated skin equivalents, as well as in antioxidant enzymes, glutathione S-transferases A1–2 (GSTA1–2), GSTA3 and GSTA4. These data demonstrate that CEES induces rapid cellular damage, cytotoxicity and inflammation in full-thickness skin equivalents. These effects are similar to human responses to vesicants in vivo and suggest that the full thickness skin equivalent is a useful in vitro model to characterize the biological effects of mustards and to develop potential therapeutics. PMID:20840853

  10. Equivalent intraperitoneal doses of ibuprofen supplemented in drinking water or in diet: a behavioral and biochemical assay using antinociceptive and thromboxane inhibitory dose-response curves in mice.

    PubMed

    Salama, Raghda A M; El Gayar, Nesreen H; Georgy, Sonia S; Hamza, May

    2016-01-01

    Background. Ibuprofen is used chronically in different animal models of inflammation by administration in drinking water or in diet due to its short half-life. Though this practice has been used for years, ibuprofen doses were never assayed against parenteral dose-response curves. This study aims at identifying the equivalent intraperitoneal (i.p.) doses of ibuprofen, when it is administered in drinking water or in diet. Methods. Bioassays were performed using formalin test and incisional pain model for antinociceptive efficacy and serum TXB2 for eicosanoid inhibitory activity. The dose-response curve of i.p. administered ibuprofen was constructed for each test using 50, 75, 100 and 200 mg/kg body weight (b.w.). The dose-response curves were constructed of phase 2a of the formalin test (the most sensitive phase to COX inhibitory agents), the area under the 'change in mechanical threshold'-time curve in the incisional pain model and serum TXB2 levels. The assayed ibuprofen concentrations administered in drinking water were 0.2, 0.35, 0.6 mg/ml and those administered in diet were 82, 263, 375 mg/kg diet. Results. The 3 concentrations applied in drinking water lay between 73.6 and 85.5 mg/kg b.w., i.p., in case of the formalin test; between 58.9 and 77.8 mg/kg b.w., i.p., in case of the incisional pain model; and between 71.8 and 125.8 mg/kg b.w., i.p., in case of serum TXB2 levels. The 3 concentrations administered in diet lay between 67.6 and 83.8 mg/kg b.w., i.p., in case of the formalin test; between 52.7 and 68.6 mg/kg b.w., i.p., in case of the incisional pain model; and between 63.6 and 92.5 mg/kg b.w., i.p., in case of serum TXB2 levels. Discussion. The increment in pharmacological effects of different doses of continuously administered ibuprofen in drinking water or diet do not parallel those of i.p. administered ibuprofen. It is therefore difficult to assume the equivalent parenteral daily doses based on mathematical calculations.

  11. Estimates of absorbed dose in different organs in children treated with radium for skin hemangiomas

    SciTech Connect

    Lundell, M.

    1994-12-01

    Between 1930 and 1959, more than 10,000 infants were treated at Radiumhemmet, Stockholm, with radium ({sup 226}Ra) needles and/or tubes for hemangioma of the skin. Absorbed dose to the brain, eye lenses, parotid glands, thyroid gland, breast enlarge, lungs, stomach, intestine, ovaries, testicles and bone marrow were calculated for each individual. The mean absorbed dose to the different organs ranged from 0.06 to 0.48 Gy. The highest absorbed dose was given to the breast (maximum 47.7 Gy). There was a wide dose range for each organ which was due mainly to differences in the distance between the applicator and the organ. The absorbed dose to all organs decreased on average by 32% during the study period. This was due to a 25% decrease in the treatment time and a change in the distribution of the treatment sites. 17 refs., 4 figs., 4 tabs.

  12. Morphological differences in the response of mouse small intestine to radiobiologically equivalent doses of X and neutron irradiation

    SciTech Connect

    Carr, K.E.; Hamlet, R.; Nias, A.H.; Watt, C.

    1984-01-01

    A scale has been developed to describe the effects of radiation on small intestinal villi. The scale has been used to compare the damage done to the villi in the period 0-5 days after irradiation by X-irradiation or neutron irradiation, using 10 Gy X-rays and 5 Gy neutrons, doses which are radiobiologically equivalent when assessed by the microcolony assay method. Use of the scale indicates that the damage done to the villi by neutrons is greater than that produced by X-rays. This has implications for the interpretation of radiobiological equivalent doses (R.B.E.). Resin light microscopy and transmission electron microscopy (T.E.M.) have also been used to examine small intestinal damage after 10 Gy X-irradiation and 5 Gy neutron irradiation. Differences include variations in crypt shape, mitotic activity and the proportion of crypts which are heavily parasitised. As well as the differences in villous shape which have been reflected in the different values on the scoring system, there are also variations in the response of the constituent cells of the epithelial compartment of the villi. In general, the effect of the neutron irradiation is more severe than that of the X-rays, particularly as would be suggested by a simple quantitation of crypt regeneration.

  13. Improvement in severe onchocercal skin disease after a single dose of ivermectin.

    PubMed

    Pacqué, M; Elmets, C; Dukuly, Z D; Muñoz, B; White, A T; Taylor, H R; Greene, B M

    1991-05-01

    Skin disease is the most common clinically important manifestation of onchocerciasis. Ivermectin, a newly available drug, is well tolerated and effective in Onchocerca volvulus infection. However, little information is available regarding its effect on onchocercal skin disease. The purpose of this study was to examine, in patients with well-characterized onchodermatitis, the effect of a single dose of ivermectin. Twenty-one persons with severe onchodermatitis were followed over a 6-month period. In order to evaluate the effect of ivermectin on their skin lesions, photographic transparencies were made before treatment and at 3 and 6 months after treatment. These were then evaluated in a blinded fashion. Following a single dose of 150 micrograms/kg, there was a significant improvement in dermatitis in the first 3 months after treatment. All 14 persons with the worst skin disease showed improvement. The drug had no demonstrable effect on depigmented lesions over the period of observation. Treatment was well tolerated. Single-dose ivermectin shows promise as the first acceptable treatment for severe onchocercal dermatitis.

  14. In vitro evaluation of chloroaluminum phthalocyanine nanoemulsion and low-level laser therapy on human skin dermal equivalents and bone marrow mesenchymal stem cells.

    PubMed

    Primo, F L; da Costa Reis, M B; Porcionatto, M A; Tedesco, A C

    2011-01-01

    Nanotechnology and tissue engineering are promising scientific fields in the development of advanced materials useful to human health. This article describes the preparation of a nanocarrier for the controlled release of a photosensitizer compound associated with low-level light therapy for skin wound healing treatment and applicable to other skin diseases. A biological model was used as an in vitro skin equivalent based on a three-dimensional culture of fibroblasts and mesenchymal stem cells and denominated by dermal equivalent (DE). Results show that it is possible to use the photomodulation process to control the wound healing in a scratching process and to induce the biomolecules release, both of which are related with the inflammatory wound healing process. In the studies, the MMP-2 and MMP-9 expression from zymography analyses were evaluated. All results showed a dependence on enzymatic activity relating to lowlevel laser applications which indicates a potential application in wound healing processes based on phototherapy and nanotechnology.

  15. Efficacy of a single high dose versus multiple low doses of LLLT on wounded skin fibroblasts

    NASA Astrophysics Data System (ADS)

    Hawkins, Denise H.; Abrahamse, Heidi

    2007-07-01

    Background/purpose: In vivo studies have demonstrated that phototherapy accelerates wound healing in the clinical environment; however the exact mechanism is still not completely understood. The main focus of this study was to use in vitro laboratory results to establish an effective treatment regimen that may be practical and applicable to the clinical environment. This in vitro study aimed to compare the cellular responses of wounded fibroblasts following a single exposure of 5 J/cm2 or multiple exposures of low doses (2.5 J/cm2 or 5 J/cm2) on one day of the week to a single application of a higher dose (16 J/cm2) on day 1 and day 4. Methodology: Cellular responses to Helium-Neon (632.8 nm) laser irradiation were evaluated by measuring changes in cell morphology, cell viability, cell proliferation, membrane integrity and DNA damage. Results: Wounded cells exposed to 5 J/cm2 on day 1 and day 4 showed an increase in cell viability, increase in the release of bFGF, increase in cell density, decrease in ALP enzyme activity and decrease in caspase 3/7 activity indicating a stimulatory effect. Wounded cells exposed to three doses of 5 J/cm2 on day 1 showed a decrease in cell viability and cell proliferation and an increase in LDH cytotoxicity and DNA damage indicating an inhibitory effect. Conclusion: Results indicate that cellular responses are influenced by the combination of dose administered, number of exposures and time between exposures. Single doses administered with sufficient time between exposures is more beneficial to restoring cell function than multiple doses within a short period. Although this work confirms previous reports on the cumulative effect of laser irradiation it provides essential information for the initiation of in vivo clinical studies.

  16. Objective method to report planner-independent skin/rib maximal dose in balloon-based high dose rate (HDR) brachytherapy for breast cancer

    SciTech Connect

    Kim, Yongbok; Trombetta, Mark G.

    2011-04-15

    Purpose: An objective method was proposed and compared with a manual selection method to determine planner-independent skin and rib maximal dose in balloon-based high dose rate (HDR) brachytherapy planning. Methods: The maximal dose to skin and rib was objectively extracted from a dose volume histogram (DVH) of skin and rib volumes. A virtual skin volume was produced by expanding the skin surface in three dimensions (3D) external to the breast with a certain thickness in the planning computed tomography (CT) images. Therefore, the maximal dose to this volume occurs on the skin surface the same with a conventional manual selection method. The rib was also delineated in the planning CT images and its maximal dose was extracted from its DVH. The absolute (Abdiff=|D{sub max}{sup Man}-D{sub max}{sup DVH}|) and relative (Rediff[%]=100x(|D{sub max}{sup Man}-D{sub max}{sup DVH}|)/D{sub max}{sup DVH}) maximal skin and rib dose differences between the manual selection method (D{sub max}{sup Man}) and the objective method (D{sub max}{sup DVH}) were measured for 50 balloon-based HDR (25 MammoSite and 25 Contura) patients. Results: The average{+-}standard deviation of maximal dose difference was 1.67%{+-}1.69% of the prescribed dose (PD). No statistical difference was observed between MammoSite and Contura patients for both Abdiff and Rediff[%] values. However, a statistically significant difference (p value <0.0001) was observed in maximal rib dose difference compared with maximal skin dose difference for both Abdiff (2.30%{+-}1.71% vs 1.05%{+-}1.43%) and Rediff[%] (2.32%{+-}1.79% vs 1.21%{+-}1.41%). In general, rib has a more irregular contour and it is more proximally located to the balloon for 50 HDR patients. Due to the inverse square law factor, more dose difference was observed in higher dose range (D{sub max}>90%) compared with lower dose range (D{sub max}<90%): 2.16%{+-}1.93% vs 1.19%{+-}1.25% with p value of 0.0049. However, the Rediff[%] analysis eliminated the

  17. Fentanyl tolerance in the treatment of cancer pain: a case of successful opioid switching from fentanyl to oxycodone at a reduced equivalent dose.

    PubMed

    Sutou, Ichiro; Nakatani, Toshihiko; Hashimoto, Tatsuya; Saito, Yoji

    2015-06-01

    Opioids are not generally deemed to have an analgesic ceiling effect on cancer pain. However, there have been occasional reports of tolerance to opioid development induced by multiple doses of fentanyl. The authors report a case of suspected tolerance to the analgesic effect of opioid, in which an increasing dose of fentanyl failed to relieve the patient's cancer pain symptoms, but opioid switching to oxycodone injections enabled a dose reduction to below the equivalent dose conversion ratio. The patient was a 60-year-old man diagnosed with pancreatic body carcinoma with multiple metastases. The base dose consisted of 12 mg/day of transdermal fentanyl patches (equivalent to 3.6 mg/day, 150 μg/h fentanyl injection), and rescue therapy consisted of 10 mg immediate-release oxycodone powders. Despite the total daily dose of fentanyl reaching 5.6 mg (equivalent to 560 mg oral morphine), the analgesic effect was inadequate; thus, an urgent adjustment was necessary. Due to the moderate dose of fentanyl, the switch to oxycodone injection was done incrementally at a daily dose equivalent to 25% of the fentanyl injection. The total dose of oxycodone was replaced approximately 53.5% of the dose of fentanyl prior to opioid switching.

  18. Changing Default Fluoroscopy Equipment Settings Decreases Entrance Skin Dose in Patients.

    PubMed

    Canales, Benjamin K; Sinclair, Lindsay; Kang, Diana; Mench, Anna M; Arreola, Manuel; Bird, Vincent G

    2016-04-01

    Proper fluoroscopic education and protocols may reduce the patient radiation dose but few prospective studies in urology have been performed. Using optically stimulated luminescent dosimeters we tested whether fluoroscopy time and/or entrance skin dose would decrease after educational and radiation reduction protocols. At default manufacturer settings fluoroscopy time and entrance skin dose were prospectively measured using optically stimulated luminescent dosimeters in patients undergoing ureteroscopy, retrograde pyelogram/stent or percutaneous nephrolithotomy with access for stone disease. A validated radiation safety competency test was administered to urology faculty and residents before and after web based, hands-on fluoroscopy training. Default fluoroscopy settings were changed from continuous to intermittent pulse rate and from standard to half-dose output. Fluoroscopy time and entrance skin dose were then measured again. The cohorts of 44 pre-protocol and 50 post-protocol patients with stones were similarly matched. The change in mean fluoroscopy time and entrance skin dose from pre-protocol to post-protocol was -0.6 minutes and -11.6 mGy (33%) for percutaneous nephrolithotomy (p = 0.62 and <0.001), 0.5 minutes and -0.1 mGy (34%) for ureteroscopy (p = 0.42 and 0.31), and 0.1 minute and -0.1 mGy (29%) for retrograde pyelogram/stent (p = 0.85 and 0.49, respectively). Urologist post-training test scores increased 30% from pretraining scores (p = 0.1). Radiation safety training protocols improved clinical knowledge but did not significantly alter fluoroscopy time. Changing equipment default settings to intermittent pulse rate (12 frames per second) and half-dose lowered the entrance skin dose by 30% across all endourology patients but most significantly during percutaneous nephrolithotomy. To limit patient radiation exposure fluoroscopy default settings should be decreased before all endourology procedures and image equipment manufacturers should consider

  19. NOTE: Variations in skin dose associated with linac bed material at 6 MV x-ray energy

    NASA Astrophysics Data System (ADS)

    Butson, Martin J.; Cheung, Tsang; Yu, Peter K. N.; Webb, Belinda

    2002-01-01

    Treatment with radiotherapy x-rays at 6 MV energy produces a build-up effect whereby a smaller dose is delivered to the patient's skin compared to the tumour dose. With anterior fields, no material is normally placed over the patient's skin, thus providing the maximum skin sparing possible with the beam configuration used. A posterior beam normally passes through the treatment couch top and increases the dose delivered to the patient's skin. Both the Mylar sheeting and the support ribbing material produce a significant increase in skin dose. Measurements at 6 MV have shown that the basal cell layer dose can be increased by up to 51% of maximum dose with a carbon fibre/Mylar couch and by 28% for a tennis string/Mylar couch when compared to anterior beams. These values are associated with the position of the carbon fibre or tennis string ribbing. Dermal layer doses are increased by up to 30 and 24% of maximum dose for carbon fibre and tennis string, respectively. These values include a combination of dose due to the support ribbing and the Mylar sheeting. Due to the variability in patient positioning on the couch top, these increases would be spread out over the skin surface producing an average increase per unit area at the basal layer of up to 32 and 20% of the maximum, respectively, for carbon fibre and tennis string couch tops and 21 and 12% at the dermal layer compared to dose at Dmax.

  20. Estimating neutron dose equivalent rates from heavy ion reactions around 10 MeV amu(-1) using the PHITS code.

    PubMed

    Iwamoto, Yosuke; Ronningen, R M; Niita, Koji

    2010-04-01

    It has been sometimes necessary for personnel to work in areas where low-energy heavy ions interact with targets or with beam transport equipment and thereby produce significant levels of radiation. Methods to predict doses and to assist shielding design are desirable. The Particle and Heavy Ion Transport code System (PHITS) has been typically used to predict radiation levels around high-energy (above 100 MeV amu(-1)) heavy ion accelerator facilities. However, predictions by PHITS of radiation levels around low-energy (around 10 MeV amu(-1)) heavy ion facilities to our knowledge have not yet been investigated. The influence of the "switching time" in PHITS calculations of low-energy heavy ion reactions, defined as the time when the JAERI Quantum Molecular Dynamics model (JQMD) calculation stops and the Generalized Evaporation Model (GEM) calculation begins, was studied using neutron energy spectra from 6.25 MeV amu(-1) and 10 MeV amu(-1) (12)C ions and 10 MeV amu(-1) (16)O ions incident on a copper target. Using a value of 100 fm c(-1) for the switching time, calculated neutron energy spectra obtained agree well with the experimental data. PHITS was then used with the switching time of 100 fm c(-1) to simulate an experimental study by Ohnesorge et al. by calculating neutron dose equivalent rates produced by 3 MeV amu(-1) to 16 MeV amu(-1) (12)C, (14)N, (16)O, and (20)Ne beams incident on iron, nickel and copper targets. The calculated neutron dose equivalent rates agree very well with the data and follow a general pattern which appears to be insensitive to the heavy ion species but is sensitive to the target material.

  1. Measurement of Neutron Dose Equivalent and its Dependence on Beam Configuration for a Passive Scattering Proton Delivery System

    SciTech Connect

    Wang Xin; Sahoo, Narayan; Zhu, Ronald X.; Zullo, John R.; Gillin, Michael T.

    2010-04-15

    Purpose: To measure the neutron dose equivalent per therapeutic proton dose (H/D) in a passive scattering proton therapy system and study its dependence on the proton energy, aperture-to-isocenter distance, spread-out Bragg peak (SOBP) width, and field size. Methods and Materials: We performed four experiments of varying proton energies, aperture-to-isocenter distances, SOBP widths, and field sizes. Etched track detectors were used to measure the neutron dose equivalent at both an in-field (isocenter, beyond the protons' range) and out-of-field (30 cm lateral to the isocenter) location in air. Results: For a nonmodulated beam with all the protons stopping in the aperture and an aperture-to-isocenter distance of 30 cm, the H/D values measured at the isocenter were approximately 0.3 mSv/Gy for all snouts with a 100-MeV beam. The H/D values increased to 10.7, 14.5, and 15.1 mSv/Gy, respectively, for small, medium, and large snouts when the beam energy increased to 250 MeV. At the out-of-field location, H/D values increased from 0.1 to 2.7, 3.0, and 3.2 mSv/Gy, respectively, for small, medium, and large snouts. When the aperture-to-isocenter distance was changed from 10 to 40 cm, the H/D value at the isocenter dropped 70%. The H/D value doubled for the modulated beam relative to the nonmodulated beam. Open apertures reduced the neutrons produced in the nozzle, but increased those produced in the phantom. Conclusions: Our data showed that changes in the four factors studied affect the H/D value in predictable ways which permits an estimate of a patient's neutron exposure.

  2. Measurement of neutron dose equivalent and its dependence on beam configuration for a passive scattering proton delivery system.

    PubMed

    Wang, Xin; Sahoo, Narayan; Zhu, Ronald X; Zullo, John R; Gillin, Michael T

    2010-04-01

    To measure the neutron dose equivalent per therapeutic proton dose (H/D) in a passive scattering proton therapy system and study its dependence on the proton energy, aperture-to-isocenter distance, spread-out Bragg peak (SOBP) width, and field size. We performed four experiments of varying proton energies, aperture-to-isocenter distances, SOBP widths, and field sizes. Etched track detectors were used to measure the neutron dose equivalent at both an in-field (isocenter, beyond the protons' range) and out-of-field (30 cm lateral to the isocenter) location in air. For a nonmodulated beam with all the protons stopping in the aperture and an aperture-to-isocenter distance of 30 cm, the H/D values measured at the isocenter were approximately 0.3 mSv/Gy for all snouts with a 100-MeV beam. The H/D values increased to 10.7, 14.5, and 15.1 mSv/Gy, respectively, for small, medium, and large snouts when the beam energy increased to 250 MeV. At the out-of-field location, H/D values increased from 0.1 to 2.7, 3.0, and 3.2 mSv/Gy, respectively, for small, medium, and large snouts. When the aperture-to-isocenter distance was changed from 10 to 40 cm, the H/D value at the isocenter dropped 70%. The H/D value doubled for the modulated beam relative to the nonmodulated beam. Open apertures reduced the neutrons produced in the nozzle, but increased those produced in the phantom. Our data showed that changes in the four factors studied affect the H/D value in predictable ways which permits an estimate of a patient's neutron exposure.

  3. Measurement of 238U and 232Th in Petrol, Gas-oil and Lubricant Samples by Using Nuclear Track Detectors and Resulting Radiation Doses to the Skin of Mechanic Workers.

    PubMed

    Misdaq, M A; Chaouqi, A; Ouguidi, J; Touti, R; Mortassim, A

    2015-10-01

    Workers in repair shops of vehicles (cars, buses, truck, etc.) clean carburetors, check fuel distribution, and perform oil changes and greasing. To explore the exposure pathway of (238)U and (232)Th and its decay products to the skin of mechanic workers, these radionuclides were measured inside petrol, gas-oil, and lubricant material samples by means of CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs), and corresponding annual committed equivalent doses to skin were determined. The maximum total equivalent effective dose to skin due to the (238)U and (232)Th series from the application of different petrol, gas-oil, and lubricant samples by mechanic workers was found equal to 1.2 mSv y(-1) cm(-2).

  4. Reconstruction of dose equivalent to the public on University of California, Davis, property from the sup 60 Co Irradiator Facility. [Contains glossary

    SciTech Connect

    Chapman, T.E.

    1991-05-01

    The {sup 60}Co Irradiator Facility, located at the Laboratory for Energy-Related Health Research (LEHR) was an indoor-outdoor gamma irradiation facility designed to study the effects of low-level continuous whole body exposure to mammals. From 1970 to 1985 outdoor radiation exposure experiments were conducted at the facility to study the effects of continuous low-level radiation exposure on beagles. Although direct exposure to the outdoor portion of the irradiator beam was controlled to within a fenced area, environmental monitoring data show that low-level radiation exposure rates were present outside of the fence perimeter. The US Department of Energy (DOE) has tasked Environmental Management Operations (EMO) to determine the potential radiation dose equivalents received by the public in UCD-operated areas adjacent to the LEHR site and to provide estimates of the associated risks to these individuals from the outdoor irradiations. EMO has reconstructed the radiation dose equivalent rates to the off-site areas using actual environmental radiation monitoring data augmented by Monte Carlo computer modeling of the radiation dose equivalent rates where necessary. This report describes the irradiator and adjacent areas, the available environmental radiation data, the computer modeling and dose equivalent rate projections, occupancy determinations, and reconstructed dose equivalents. Also a risk factor is estimated for each of the dose equivalents calculated for the public. 5 refs., 4 figs., 6 tabs.

  5. SU-F-P-44: A Direct Estimate of Peak Skin Dose for Interventional Fluoroscopy Procedures

    SciTech Connect

    Weir, V; Zhang, J

    2016-06-15

    Purpose: There is an increasing demand for medical physicist to calculate peak skin dose (PSD) for interventional fluoroscopy procedures. The dose information (Dose-Area-Product and Air Kerma) displayed in the console cannot directly be used for this purpose. Our clinical experience shows that the use of the existing methods may overestimate or underestimate PSD. This study attempts to develop a direct estimate of PSD from the displayed dose metrics. Methods: An anthropomorphic torso phantom was used for dose measurements for a common fluoroscopic procedure. Entrance skin doses were measured with a Piranha solid state point detector placed on the table surface below the torso phantom. An initial “reference dose rate” (RE) measurement was conducted by comparing the displayed dose rate (mGy/min) to the dose rate measured. The distance from table top to focal spot was taken as the reference distance (RD at the RE. Table height was then adjusted. The displayed air kerma and DAP were recorded and sent to three physicists to estimate PSD. An inverse square correction was applied to correct displayed air kerma at various table heights. The PSD estimated by physicists and the PSD by the proposed method were then compared with the measurements. The estimated DAPs were compared to displayed DAP readings (mGycm2). Results: The difference between estimated PSD by the proposed method and direct measurements was less than 5%. For the same set of data, the estimated PSD by each of three physicists is different from measurements by ±52%. The DAP calculated by the proposed method and displayed DAP readings in the console is less than 20% at various table heights. Conclusion: PSD may be simply estimated from displayed air kerma or DAP if the distance between table top and tube focal spot or if x-ray beam area on table top is available.

  6. Chip-based human liver-intestine and liver-skin co-cultures--A first step toward systemic repeated dose substance testing in vitro.

    PubMed

    Maschmeyer, Ilka; Hasenberg, Tobias; Jaenicke, Annika; Lindner, Marcus; Lorenz, Alexandra Katharina; Zech, Julie; Garbe, Leif-Alexander; Sonntag, Frank; Hayden, Patrick; Ayehunie, Seyoum; Lauster, Roland; Marx, Uwe; Materne, Eva-Maria

    2015-09-01

    Systemic repeated dose safety assessment and systemic efficacy evaluation of substances are currently carried out on laboratory animals and in humans due to the lack of predictive alternatives. Relevant international regulations, such as OECD and ICH guidelines, demand long-term testing and oral, dermal, inhalation, and systemic exposure routes for such evaluations. So-called "human-on-a-chip" concepts are aiming to replace respective animals and humans in substance evaluation with miniaturized functional human organisms. The major technical hurdle toward success in this field is the life-like combination of human barrier organ models, such as intestine, lung or skin, with parenchymal organ equivalents, such as liver, at the smallest biologically acceptable scale. Here, we report on a reproducible homeostatic long-term co-culture of human liver equivalents with either a reconstructed human intestinal barrier model or a human skin biopsy applying a microphysiological system. We used a multi-organ chip (MOC) platform, which provides pulsatile fluid flow within physiological ranges at low media-to-tissue ratios. The MOC supports submerse cultivation of an intact intestinal barrier model and an air-liquid interface for the skin model during their co-culture with the liver equivalents respectively at (1)/100.000 the scale of their human counterparts in vivo. To increase the degree of organismal emulation, microfluidic channels of the liver-skin co-culture could be successfully covered with human endothelial cells, thus mimicking human vasculature, for the first time. Finally, exposure routes emulating oral and systemic administration in humans have been qualified by applying a repeated dose administration of a model substance - troglitazone - to the chip-based co-cultures. Copyright © 2015. Published by Elsevier B.V.

  7. MOSFET dosimeter depth-dose measurements in heterogeneous tissue-equivalent phantoms at diagnostic x-ray energies

    SciTech Connect

    Jones, A.K.; Pazik, F.D.; Hintenlang, D.E.; Bolch, W.E.

    2005-10-15

    The objective of the present study was to explore the use of the TN-1002RD metal-oxide-semiconductor field effect transistor (MOSFET) dosimeter for measuring tissue depth dose at diagnostic photon energies in both homogeneous and heterogeneous tissue-equivalent materials. Three cylindrical phantoms were constructed and utilized as a prelude to more complex measurements within tomographic physical phantoms of pediatric patients. Each cylindrical phantom was constructed as a stack of seven 5-cm-diameter and 1-cm-thick discs of materials radiographically representative of either soft tissue (S), bone (B), or lung tissue (L) at diagnostic photon energies. In addition to a homogeneous phantom of soft tissue (SSSSSSS), two heterogeneous phantoms were constructed: SSBBSSS and SBLLBSS. MOSFET dosimeters were then positioned at the interface of each disc, and the phantoms were then irradiated at 66 kVp and 200 mAs. Measured values of absorbed dose at depth were then compared to predicated values of point tissue dose as determined via Monte Carlo radiation transport modeling. At depths exceeding 2 cm, experimental results matched the computed values of dose with high accuracy regardless of the dosimeter orientation (epoxy bubble facing toward or away from the x-ray beam). Discrepancies were noted, however, between measured and calculated point doses near the surface of the phantom (surface to 2 cm depth) when the dosimeters were oriented with the epoxy bubble facing the x-ray beam. These discrepancies were largely eliminated when the dosimeters were placed with the flat side facing the x-ray beam. It is therefore recommended that the MOSFET dosimeters be oriented with their flat sides facing the beam when they are used at shallow depths or on the surface of either phantoms or patients.

  8. 10 CFR 835.202 - Occupational dose limits for general employees.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... External Exposure § 835.202 Occupational dose limits for general employees. (a) Except for planned special... equivalent dose to the whole body for external exposures and the committed equivalent dose to any organ or... extremity for external exposures and the committed equivalent dose to the skin or to any extremity of...

  9. Determination of minimal erythema dose and anomalous reactions to UVA radiation by skin phototype.

    PubMed

    Pérez Ferriols, A; Aguilera, J; Aguilera, P; de Argila, D; Barnadas, M A; de Cabo, X; Carrrascosa, J M; de Gálvez Aranda, M V; Gardeazábal, J; Giménez-Arnau, A; Lecha, M; Lorente, J; Martínez-Lozano, J A; Rodríguez Granados, M T; Sola, Y; Utrillas, M P

    2014-10-01

    Phototesting is a technique that assesses the skin's sensitivity to UV radiation by determining the smallest dose of radiation capable of inducing erythema (minimal erythema dose [MED]) and anomalous responses to UV-A radiation. No phototesting protocol guidelines have been published to date. This was a multicenter prospective cohort study in which 232 healthy volunteers were recruited at 9 hospitals. Phototests were carried out with solar simulators or fluorescent broadband UV-B lamps. Each individual received a total of 5 or 6 incremental doses of erythemal radiation and 4 doses of UV-A radiation. The results were read at 24hours. At hospitals where solar simulators were used, the mean (SD) MED values were 23 (8), 28 (4), 35 (4), and 51 (6) mJ/cm(2) for skin phototypes i to iv, respectively. At hospitals where broadband UV-B lamps were used, these values were 28 (5), 32 (3), and 34 (5) mJ/cm(2) for phototypes ii to iv, respectively. MED values lower than 7, 19, 27, and 38 mJ/cm(2) obtained with solar simulators were considered to indicate a pathologic response for phototypes I to IV, respectively. MED values lower than 18, 24, and 24mJ/cm(2) obtained with broadband UV-B lamps were considered to indicate a pathologic response for phototypes ii to iv, respectively. No anomalous responses were observed at UV-A radiation doses of up to 20J/cm(2). Results were homogeneous across centers, making it possible to standardize diagnostic phototesting for the various skin phototypes and establish threshold doses that define anomalous responses to UV radiation. Copyright © 2014 Elsevier España, S.L.U. y AEDV. All rights reserved.

  10. Main clinical, therapeutic and technical factors related to patient's maximum skin dose in interventional cardiology procedures

    PubMed Central

    Journy, N; Sinno-Tellier, S; Maccia, C; Le Tertre, A; Pirard, P; Pagès, P; Eilstein, D; Donadieu, J; Bar, O

    2012-01-01

    Objective The study aimed to characterise the factors related to the X-ray dose delivered to the patient's skin during interventional cardiology procedures. Methods We studied 177 coronary angiographies (CAs) and/or percutaneous transluminal coronary angioplasties (PTCAs) carried out in a French clinic on the same radiography table. The clinical and therapeutic characteristics, and the technical parameters of the procedures, were collected. The dose area product (DAP) and the maximum skin dose (MSD) were measured by an ionisation chamber (Diamentor; Philips, Amsterdam, The Netherlands) and radiosensitive film (Gafchromic; International Specialty Products Advanced Materials Group, Wayne, NJ). Multivariate analyses were used to assess the effects of the factors of interest on dose. Results The mean MSD and DAP were respectively 389 mGy and 65 Gy cm−2 for CAs, and 916 mGy and 69 Gy cm−2 for PTCAs. For 8% of the procedures, the MSD exceeded 2 Gy. Although a linear relationship between the MSD and the DAP was observed for CAs (r=0.93), a simple extrapolation of such a model to PTCAs would lead to an inadequate assessment of the risk, especially for the highest dose values. For PTCAs, the body mass index, the therapeutic complexity, the fluoroscopy time and the number of cine frames were independent explanatory factors of the MSD, whoever the practitioner was. Moreover, the effect of technical factors such as collimation, cinematography settings and X-ray tube orientations on the DAP was shown. Conclusion Optimising the technical options for interventional procedures and training staff on radiation protection might notably reduce the dose and ultimately avoid patient skin lesions. PMID:22457404

  11. Increased dose near the skin due to electromagnetic surface beacon transponder.

    PubMed

    Ahn, Kang-Hyun; Manger, Ryan; Halpern, Howard J; Aydogan, Bulent

    2015-05-08

    The purpose of this study was to evaluate the increased dose near the skin from an electromagnetic surface beacon transponder, which is used for localization and tracking organ motion. The bolus effect due to the copper coil surface beacon was evaluated with radiographic film measurements and Monte Carlo simulations. Various beam incidence angles were evaluated for both 6 MV and 18 MV experimentally. We performed simulations using a general-purpose Monte Carlo code MCNPX (Monte Carlo N-Particle) to supplement the experimental data. We modeled the surface beacon geometry using the actual mass of the glass vial and copper coil placed in its L-shaped polyethylene terephthalate tubing casing. Film dosimetry measured factors of 2.2 and 3.0 enhancement in the surface dose for normally incident 6 MV and 18 MV beams, respectively. Although surface dose further increased with incidence angle, the relative contribution from the bolus effect was reduced at the oblique incidence. The enhancement factors were 1.5 and 1.8 for 6 MV and 18 MV, respectively, at an incidence angle of 60°. Monte Carlo simulation confirmed the experimental results and indicated that the epidermal skin dose can reach approximately 50% of the dose at dmax at normal incidence. The overall effect could be acceptable considering the skin dose enhancement is confined to a small area (~ 1 cm2), and can be further reduced by using an opposite beam technique. Further clinical studies are justified in order to study the dosimetric benefit versus possible cosmetic effects of the surface beacon. One such clinical situation would be intact breast radiation therapy, especially large-breasted women.

  12. The use of Monte Carlo technique to optimize the dose distribution in total skin irradiation

    NASA Astrophysics Data System (ADS)

    Poli, M. E. R.; Pereira, S. A.; Yoriyaz, H.

    2001-06-01

    Cutaneous T-cell lymphoma (mycosis fungoides) is an indolent disease with a low percentage of cure. Total skin irradiation using an electron beam has become an efficient treatment of mycosis fungoides with curative intention, with success in almost 40% of the patients. In this work, we propose the use of a Monte Carlo technique to simulate the dose distribution in the patients during total skin irradiation treatments. Use was made of MCNP-4B, a well known and established code used to simulate transport of electrons, photons and neutrons through matter, especially in the area of reactor physics, and also finding increasing utility in medical physics. The goal of our work is to simulate different angles between each beam with a fixed treatment distance in order to obtain a uniform dose distribution in the patient.

  13. Measurement of radiotherapy x-ray skin dose on a chest wall phantom.

    PubMed

    Quach, K Y; Morales, J; Butson, M J; Rosenfeld, A B; Metcalfe, P E

    2000-07-01

    Sufficient skin dose needs to be delivered by a radiotherapy chest wall treatment regimen to ensure the probability of a near surface tumor recurrence is minimized. To simulate a chest wall treatment a hemicylindrical solid water phantom of 7.5 cm radius was irradiated with 6 MV x-rays using 20x20 cm2 and 10x20 cm2 fields at 100 cm source surface distance (SSD) to the base of the phantom. A surface dose profile was obtained from 0 to 180 degrees, in 10 degrees increments around the circumference of the phantom. Dosimetry results obtained from radiochromic film (effective depth of 0.17 mm) were used in the investigation, the superficial doses were found to be 28% (of Dmax) at the 0 degrees beam entry position and 58% at the 90 degrees oblique beam position. Superficial dose results were also obtained using extra thin thermoluminescent dosimeters (TLD) (effective depth 0.14 mm) of 30% at 0 degrees, 57% at 90 degrees, and a metal oxide semiconductor field effect transistor (MOSFET) detector (effective depth 0.5 mm) of 43% at 0 degrees, 62% at 90 degrees. Because the differences in measured superficial doses were significant and beyond those related to experimental error, these differences are assumed to be mostly attributable to the effective depth of measurement of each detector. We numerically simulated a bolus on/bolus off technique and found we could increase the coverage to the skin. Using an alternate "bolus on," "bolus off" regimen, the skin would receive 36.8 Gy at 0 degrees incidence and 46.4 Gy at 90 degrees incidence for a prescribed midpoint dose of 50 Gy. From this work it is evident that, as the circumference of the phantom is traversed the SSD increases and hence there is an inverse square fluence fall-off, this is more than offset by the increase in skin dose due to surface curvature to a plateau at about 90 degrees. Beyond this angle it is assumed that beam attenuation through the phantom and inverse square fall-off is causing the surface dose to

  14. High-dose immunosuppressant alters the immunological status of New Zealand white rabbits following skin transplantation

    PubMed Central

    CHENG, PEILUN; ZHONG, LIMING; JIANG, ZESHENG; WANG, YAN; PAN, MINGXIN; GAO, YI

    2015-01-01

    The aim of this study was to investigate the effect of an immunosuppressant on the immunological status of New Zealand white rabbits after skin grafting, and to evaluate a method for monitoring the immunological status of subjects with skin transplants. The rabbits were randomly divided into allograft rejection, autograft tolerance, nontransplant, allograft low-dose immunosuppressant and allograft high-dose immunosuppressant groups. The rabbits in the low- and high-dose immunosuppressant groups were treated with cyclosporine A intravenously 8 h prior to skin transplantation and once daily following transplantation at doses of 2 and 25 mg/kg, respectively. At 12 days after skin transplantation, the spleens of donor (female) rabbits and recipient (male) rabbits were harvested for the preparation of single-cell suspensions. The splenocytes from recipient and donor rabbits were labeled with 0.3 or 6 µM carboxy fluorescein diacetate succinimidyl ester, respectively, and a mixed cell suspension was prepared. The final preparation was intravenously injected into recipient New Zealand white rabbits. The ratio of the two fluorescently labeled cell populations in the peripheral blood was measured using flow cytometry at 1, 2, 4 and 8 h after the injection, and the cell death rate was calculated. Histological analysis was also performed on samples collected at the time of splenectomy. The cell death rates of the allograft rejection and low-dose immunosuppressant groups reached their highest levels 8 h after the injection of spleen cell suspension. Allogeneic spleen cells from donor male rabbits were almost completely removed within 8 h of injection. The cell death rate increased slowly in the nontransplant, autograft and high-dose immunosuppressant groups without specificity. This study provides a specific method for the in vivo monitoring of the immunological status of patients after skin grafting. This method can quickly and accurately detect the immunological status of

  15. Effects of ISS equivalent ionizing radiation dose on Human T-lymphocytes

    NASA Astrophysics Data System (ADS)

    Meloni, Maria Antonia; Pani, Giuseppe; Benotmane, Rafi; Mastroleo, Felice; Aboul-El-Ardat, Khalil; Janssen, Ann; Leysen, Liselotte; Vanhavere, Filip; Leys, Natalie; Galleri, Grazia; Pippia, Proto; Baatout, Sarah

    One of the objectives of the current international space programs is to investigate the effects of cosmic environment on Humans. It is known that during a long exposure to the space conditions, including ionizing radiations and microgravity, the immune system of the astronauts is impaired. In past years several experiments were performed to identify responsible factors of in vitro mitogenic activation process in human T-lymphocytes under simulated microgravity effect and during dedicated space missions. It come out that the lack of immune response in microgravity occurs at the cellular and molecular level. In order to evaluate effects on pure primary T-lymphocytes from peripheral blood exposed to International Space Station (ISS)-like ionizing radiation, we applied a mixture of Cesium-137, as representative of low energy particles, and Californium-252, as representative of hight energy particles, with rate similar to those monitored inside the ISS during previous space mission (Goossens et all. 2006). This facility is available at SCK•CEN (Belgium) (Mastroleo et al., 2009). Although the dose received by the cells was relatively low, flow cytometry analysis 24 hours after irradiation showed a decrease in cell viability coupled with the increase of the caspase-3 activity. However, Bcl-2 activity did not seem to be affected by the radiation. Furthermore, activation of cells induced an increase of the cell size and alteration of cellular morphology. Cell cycle as well as 8-oxo-G were also modified upon radiation and activation. Gene expression analysis shows a modulation of genes rather as a consequence of exposure than with the activation status. 330 genes have been identified to be significantly modulated in function of the time and have been grouped in four different cluster representing significant expression profiles. Preliminary functional analysis shows mainly genes involved in the immune response and inflammatory diseases as well as oxidative stress and

  16. Clinical implementation of total skin electron irradiation treatment with a 6 MeV electron beam in high-dose total skin electron mode

    SciTech Connect

    Lucero, J. F.; Rojas, J. I.

    2016-07-07

    Total skin electron irradiation (TSEI) is a special treatment technique offered by modern radiation oncology facilities, given for the treatment of mycosis fungoides, a rare skin disease, which is type of cutaneous T-cell lymphoma [1]. During treatment the patient’s entire skin is irradiated with a uniform dose. The aim of this work is to present implementation of total skin electron irradiation treatment using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films.

  17. Low-dose radiation modifies skin response to acute gamma-rays and protons.

    PubMed

    Mao, Xiao Wen; Pecaut, Michael J; Cao, Jeffrey D; Moldovan, Maria; Gridley, Daila S

    2013-01-01

    The goal of the present study was to obtain pilot data on the effects of protracted low-dose/low-dose-rate (LDR) γ-rays on the skin, both with and without acute gamma or proton irradiation (IR). Six groups of C57BL/6 mice were examined: a) 0 Gy control, b) LDR, c) Gamma, d) LDR+Gamma, e) Proton, and f) LDR+Proton. LDR radiation was delivered to a total dose of 0.01 Gy (0.03 cGy/h), whereas the Gamma and Proton groups received 2 Gy (0.9 Gy/min and 1.0 Gy/min, respectively). Assays were performed 56 days after exposure. Skin samples from all irradiated groups had activated caspase-3, indicative of apoptosis. The significant (p<0.05) increases in immunoreactivity in the Gamma and Proton groups were not present when LDR pre-exposure was included. However, the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay for DNA fragmentation and histological examination of hematoxylin and eosin-stained sections revealed no significant differences among groups, regardless of radiation regimen. The data demonstrate that caspase-3 activation initially triggered by both forms of acute radiation was greatly elevated in the skin nearly two months after whole-body exposure. In addition, LDR γ-ray priming ameliorated this response.

  18. Feasibility of a semiconductor dosimeter to monitor skin dose in interventional radiology.

    PubMed

    Meyer, P; Regal, R; Jung, M; Siffert, P; Mertz, L; Constantinesco, A

    2001-10-01

    The design and preliminary test results of a semiconductor silicon dosimeter are presented in this article. Use of this dosimeter is foreseen for real-time skin dose control in interventional radiology. The strong energy dependence of this kind of radiation detector is well overcome by filtering the silicon diode. Here, the optimal filter features have been calculated by numerical Monte Carlo simulations. A prototype has been built and tested in a radiological facility. The first experimental results show a good match between the filtered semiconductor diode response and an ionization chamber response, within 2% fluctuation in a 2.2 to 4.1 mm Al half-value layer (HVL) energy range. Moreover, the semiconductor sensor response is linear from 0.02 Gy/min to at least 6.5 Gy/min, covering the whole dose rate range found in interventional radiology. The results show that a semiconductor dosimeter could be used to monitor skin dose during the majority of procedures using x-rays below 150 keV. The use of this device may assist in avoiding radiation-induced skin injuries and lower radiation levels during interventional procedures.

  19. 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

  20. Dose doubling, relative potency, and dose equivalence of potassium-sparing diuretics affecting blood pressure and serum potassium: systematic review and meta-analyses.

    PubMed

    Roush, George C; Ernst, Michael E; Kostis, John B; Yeasmin, Shamima; Sica, Domenic A

    2016-01-01

    Potassium-sparing diuretics (PSDs) are valuable antihypertensives with additional benefits unrelated to control of systolic blood pressure (SBP). However, their key parameters affecting SBP and serum potassium are poorly defined, fostering underutilization. Consequently, we conducted systematic reviews and meta-analyses, yielding 3668 articles and ultimately 84 randomized comparisons. For office SBP, overall placebo-adjusted changes were triamterene -1.9 (low dose only), amiloride -9.9, spironolactone -13.2, and eplerenone -9.2. Differences in antihypertensive effect were due to potency rather than efficacy. Doubling amiloride, eplerenone, and spironolactone doses reduced SBP (95% confidence limits) on average by -2.3 (-3.1, -1.5). Relative antihypertensive potencies were spironolactone>amiloride>eplerenone. Spironolactone had significantly greater antihypertensive potency than amiloride, -4.0 (-7.4, -0.6), and eplerenone, -5.5 (-7.4, -3.6). Dose equivalencies were eplerenone-spironolactone 4.5-to-1 (e.g., eplerenone 125∼spironolactone 25), amiloride-spironolactone 3.3-to-1, and eplerenone-amiloride 1.4-to-1. Increases in serum potassium from amiloride and spironolactone at commonly used doses averaged 0.14-0.29 mEq/l; the dose doubling effect was 0.16 (0.10, 0.22). Spironolactone caused greater hyperkalemia than amiloride across their dose ranges: 0.14, P = 0.043. Seven features make important bias unlikely: a comprehensive literature search, adjustment for covariates, all models explaining 95-100% of the between-study variability, similar dose doubling effects among PSDs, two different methods giving the same potency sequence, similar results from double blind comparisons, and similar results for eplerenone versus spironolactone from analysing direct comparison data (i.e., no meta-regression) for office and 24-h SBP. This synthesis accomplishes for PSDs what has already been achieved for thiazide-type diuretics and other antihypertensives and can guide

  1. Quantitative Proteomic Profiling of Low Dose Ionizing Radiation Effects in a Human Skin Model

    SciTech Connect

    Hengel, Shawna; Aldrich, Joshua T.; Waters, Katrina M.; Pasa-Tolic, Ljiljana; Stenoien, David L.

    2014-07-29

    To assess molecular responses to low doses of radiation that may be encountered during medical diagnostic procedures, nuclear accidents, or terrorist acts, a quantitative global proteomic approach was used to identify protein alterations in a reconstituted human skin tissue treated with 10 cGy of ionizing radiation. Subcellular fractionation was employed to remove highly abundant structural proteins and provide insight on radiation induced alterations in protein abundance and localization. In addition, peptides were post-fractionated using high resolution 2-dimensional liquid chromatography to increase the dynamic range of detection of protein abundance and translocation changes. Quantitative data was obtained by labeling peptides with 8-plex isobaric iTRAQ tags. A total of 207 proteins were detected with statistically significant alterations in abundance and/or subcellular localization compared to sham irradiated tissues. Bioinformatics analysis of the data indicated that the top canonical pathways affected by low dose radiation are related to cellular metabolism. Among the proteins showing alterations in abundance, localization and proteolytic processing was the skin barrier protein filaggrin which is consistent with our previous observation that ionizing radiation alters profilaggrin processing with potential effects on skin barrier functions. In addition, a large number of proteases and protease regulators were affected by low dose radiation exposure indicating that altered proteolytic activity may be a hallmark of low dose radiation exposure. While several studies have demonstrated altered transcriptional regulation occurs following low dose radiation exposures, the data presented here indicates post-transcriptional regulation of protein abundance, localization, and proteolytic processing play an important role in regulating radiation responses in complex human tissues.

  2. Multiple Methods for Assessing the Dose to Skin Exposed to Radioactive Contamination.

    PubMed

    Dubeau, J; Heinmiller, B E; Corrigan, M

    2017-04-28

    There is the possibility for a worker at a nuclear installation, such as a nuclear power reactor, a fuel production facility or a medical facility, to come in contact with radioactive contaminants. When such an event occurs, the first order of business is to care for the worker by promptly initiating a decontamination process. Usually, the radiation protection personnel performs a G-M pancake probe measurement of the contamination in situ and collects part or all of the radioactive contamination for further laboratory analysis. The health physicist on duty must then perform, using the available information, a skin dose assessment that will go into the worker's permanent dose record. The contamination situations are often complex and the dose assessment can be laborious. This article compares five dose assessment methods that involve analysis, new technologies and new software. The five methods are applied to 13 actual contamination incidents consisting of direct skin contact, contamination on clothing and contamination on clothing in the presence of an air gap between the clothing and the skin. This work shows that, for the cases studied, the methods provided dose estimates that were usually within 12% (1σ) of each other, for those cases where absolute activity information for every radionuclide was available. One method, which relies simply on a G-M pancake probe measurement, appeared to be particularly useful in situations where a contamination sample could not be recovered for laboratory analysis. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Comparison of skin stripping, in vitro release, and skin blanching response methods to measure dose response and similarity of triamcinolone acetonide cream strengths from two manufactured sources.

    PubMed

    Pershing, Lynn K; Bakhtian, Shahrzad; Poncelet, Craig E; Corlett, Judy L; Shah, Vinod P

    2002-05-01

    The collective studies compare in vitro drug release, in vivo skin stripping, and skin blanching response methods for dose responsiveness and bioequivalence assessment of triamcinolone acetonide cream products, as a function of application duration, drug concentration, and manufacturer source. Commercially available triamcinolone acetonide creams (0.025%, 0.1%, and 0.5%) from two manufacturers were evaluated in vitro for rate and extent of drug release across synthetic membranes and in vivo for rate, extent, and variability of drug uptake into human stratum corneum and skin blanching response in human forearm skin. Data demonstrate that increasing triamcinolone acetonide cream concentration applied increased the rate and extent of drug released in vitro as well as the extent of drug uptake and skin blanching response in human skin in vivo. No difference (p < 0.05) between the two sources of 0.1% or 0.5% creams was measured by the skin stripping or skin blanching response methods. Dermatopharmacokinetic analysis of triamcinonide acetonide in vivo is therefore dose responsive to drug concentration applied and application duration and agrees with in vivo skin blanching results. Data support the use of dermatopharmacokinetic methods for bioequivalence and bioavailability assessment of topical drug products.

  4. Direct measurement of patient's entrance skin dose during neurointerventional procedure to avoid further radiation-induced skin injuries.

    PubMed

    Hayakawa, Mikito; Moritake, Takashi; Kataoka, Fumikatsu; Takigawa, Tomoji; Koguchi, Yasuhiro; Miyamoto, Yuka; Akahane, Keiichi; Matsumaru, Yuji

    2010-07-01

    Although several cases of radiation-induced skin injury (RSI) have been reported in association with neurointerventional procedures such as endovascular embolization for cerebral aneurysm, cerebral arteriovenous malformation, and dural arteriovenous fistula, in most cases the absorbed doses are not measured directly; therefore, we built the first direct measurement system that enables the ideal dosimetry for entrance skin dose (ESD) during neurointerventional procedures to be easily determined. This system was then applied to a 55-year-old man who underwent two transvenous embolizations with a 2-month interval, for a right cavernous sinus dural arteriovenous fistula, to establish the efficacy of precise mapping of ESDs. Throughout the procedures, the patient wore a fitted dosimetry cap that contained 60 radiophotoluminescence glass dosimeter (RPLGD) chips. After the first procedure, temporary epilation occurred in the occipital region. Precise mapping of ESDs revealed that this region was exposed to 4.2Gy. In the first procedure, the X-ray tube was generally positioned straight for an optimal posterior-anterior view; however, in the second procedure we intermittently used the second-best position to prevent further RSI. In this position, the maximum ESD was 1.0Gy in the right posterior-temporal region and the epilation site was exposed to

  5. Persistent DNA Damage after High Dose In Vivo Gamma Exposure of Minipig Skin

    PubMed Central

    Ahmed, Emad A.; Agay, Diane; Schrock, Gerrit; Drouet, Michel; Meineke, Viktor; Scherthan, Harry

    2012-01-01

    Background Exposure to high doses of ionizing radiation (IR) can lead to localized radiation injury of the skin and exposed cells suffer dsDNA breaks that may elicit cell death or stochastic changes. Little is known about the DNA damage response after high-dose exposure of the skin. Here, we investigate the cellular and DNA damage response in acutely irradiated minipig skin. Methods and Findings IR-induced DNA damage, repair and cellular survival were studied in 15 cm2 of minipig skin exposed in vivo to ∼50 Co-60 γ rays. Skin biopsies of control and 4 h up to 96 days post exposure were investigated for radiation-induced foci (RIF) formation using γ-H2AX, 53BP1, and active ATM-p immunofluorescence. High-dose IR induced massive γ-H2AX phosphorylation and high 53BP1 RIF numbers 4 h, 20 h after IR. As time progressed RIF numbers dropped to a low of <1% of keratinocytes at 28–70 days. The latter contained large RIFs that included ATM-p, indicating the accumulation of complex DNA damage. At 96 days most of the cells with RIFs had disappeared. The frequency of active-caspase-3-positive apoptotic cells was 17-fold increased 3 days after IR and remained >3-fold elevated at all subsequent time points. Replicating basal cells (Ki67+) were reduced 3 days post IR followed by increased proliferation and recovery of epidermal cellularity after 28 days. Conclusions Acute high dose irradiation of minipig epidermis impaired stem cell replication and induced elevated apoptosis from 3 days onward. DNA repair cleared the high numbers of DBSs in skin cells, while RIFs that persisted in <1% cells marked complex and potentially lethal DNA damage up to several weeks after exposure. An elevated frequency of keratinocytes with persistent RIFs may thus serve as indicator of previous acute radiation exposure, which may be useful in the follow up of nuclear or radiological accident scenarios. PMID:22761813

  6. SU-E-T-233: Modeling Linac Couch Effects On Attenuation and Skin Dose

    SciTech Connect

    Xiong, L; Halvorsen, P

    2014-06-01

    Purpose: Treatment couch tops in medical LINAC rooms lead to attenuation to beams penetrating them, plus higher skin dose which can become a significant concern with the high fraction doses associated with Stereotactic Body Radiation Therapy. This work measures the attenuation and shallow depth dose due to a BrainLab couch, and studies the modeling of the couch top in our treatment planning system (TPS) as a uniform solid material with homogeneous density. Methods: LINAC photon beams of size 10×10 cm and nominal energy 6 MV were irradiated from different gantry angles on a stack of solid water. Depth dose were measured with two types of parallel plate chambers, MPPK and Markus. In the Philips Pinnacle TPS, the couch was modeled as a slab with varying thickness and density. A digital phantom of size 30×30×10 cm with density 1 g/cc was created to simulate the measurement setup. Both the attenuation and skin dose effects due to the couch were studied. Results: An orthogonal attenuation rate of 3.2% was observed with both chamber measurements. The attenuation can be modeled by couch models of varying thicknesses. Once the orthogonal attenuation was modeled well, the oblique beam attenuation in TPS agreed with measurement within 1.5%. The depth dose at shallow depth (0.5 cm) was also shown to be modeled correctly within 1.5% of the measurement using a 12 mm thick couch model with density of 0.9 g/cc. Agreement between calculation and measurement diverges at very shallow depths (≤1 mm) but remains acceptable (<5%) with the aforementioned couch model parameters. Conclusion: Modeling the couch top as a uniform solid in a treatment planning system can predict both the attenuation and surface dose simultaneously well within clinical tolerance in the same model.

  7. Comparison of cutaneous bioavailability of cosmetic preparations containing caffeine or alpha-tocopherol applied on human skin models or human skin ex vivo at finite doses.

    PubMed

    Dreher, Frank; Fouchard, Frédéric; Patouillet, Claire; Andrian, Michèle; Simonnet, Jean-Thierry; Benech-Kieffer, Florence

    2002-01-01

    The use of human skin models for performing cutaneous bioavailability studies has been little investigated. For instance, only few studies have been reported on human skin models dealing with vehicle effects on percutaneous penetration. The present study aimed at evaluating the influence on caffeine's and alpha-tocopherol's cutaneous bioavailability of cosmetic vehicles such as a water-in-oil emulsion, an oil-in-water emulsion, a liposome dispersion and a hydrogel applied at finite dose using the reconstructed human skin models EpiDerm and Episkin. The results were compared with those obtained in human skin ex vivo using similar experimental conditions. It was demonstrated that the rank order of solute permeability could be correctly predicted when the preparation was applied at a finite dose in human skin models, at least when solutes with far different physicochemical properties such as caffeine and alpha-tocopherol were used. If only slight effects of cosmetic vehicle on skin bioavailability were observed in human skin ex vivo, they were less predictable using skin models. Especially, alcohol-containing vehicles seemed to behave differently in EpiDerm as well as in Episkin than on human skin ex vivo. Stratum corneum intercellular lipid composition and organization of human skin models differ to some extent from that of human stratum corneum ex vivo, which contributes to less pronounced barrier properties, together with the increased hydration of the outermost stratum corneum layers of the models. These features, as well as still unknown factors, may explain the differences observed in vehicle effects in human skin ex vivo versus human skin models. Copyright 2002 S. Karger AG, Basel