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Sample records for absorbed dose delivered

  1. Absorbed dose water calorimeter

    SciTech Connect

    Domen, S.R.

    1982-01-26

    An absorbed dose water calorimeter that takes advantage of the low thermal diffusivity of water and the water-imperviousness of polyethylene film. An ultra-small bead thermistor is sandwiched between two thin polyethylene films stretched between insulative supports in a water bath. The polyethylene films insulate the thermistor and its leads, the leads being run out from between the films in insulated sleeving and then to junctions to form a wheatstone bridge circuit. Convection barriers may be provided to reduce the effects of convection from the point of measurement. Controlled heating of different levels in the water bath is accomplished by electrical heater circuits provided for controlling temperature drift and providing adiabatic operation of the calorimeter. The absorbed dose is determined from the known specific heat of water and the measured temperature change.

  2. 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.

  3. On the definition of absorbed dose

    NASA Astrophysics Data System (ADS)

    Grusell, Erik

    2015-02-01

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before.

  4. Absorbed dose thresholds and absorbed dose rate limitations for studies of electron radiation effects on polyetherimides

    NASA Technical Reports Server (NTRS)

    Long, Edward R., Jr.; Long, Sheila Ann T.; Gray, Stephanie L.; Collins, William D.

    1989-01-01

    The threshold values of total absorbed dose for causing changes in tensile properties of a polyetherimide film and the limitations of the absorbed dose rate for accelerated-exposure evaluation of the effects of electron radiation in geosynchronous orbit were studied. Total absorbed doses from 1 kGy to 100 MGy and absorbed dose rates from 0.01 MGy/hr to 100 MGy/hr were investigated, where 1 Gy equals 100 rads. Total doses less than 2.5 MGy did not significantly change the tensile properties of the film whereas doses higher than 2.5 MGy significantly reduced elongation-to-failure. There was no measurable effect of the dose rate on the tensile properties for accelerated electron exposures.

  5. Statistics of the doses absorbed by workers

    NASA Astrophysics Data System (ADS)

    Parisi, A.

    1982-10-01

    A statistical analysis of the distribution of the doses by individual workers is presented to assess existing norms. A log-normal distribution is assumed for the individual doses. A reference distribution is introduced, characterized by log-normal distribution of annual doses, average 0,5 rem (10% of the limit) and 0.1% of the individuals that will absorb more than 5 rem. Expressions are given for the probability of finding a dose in a given interval and for the fraction of the collective dose due to doses from a given interval. An example using data from medical professions in the United States shows that the fraction of workers with annual doses larger than 5 rem is not contained within the 0.1% recommended limit, and that the level of risk is not uniform between professions.

  6. An absorbed dose calorimeter for IMRT dosimetry

    NASA Astrophysics Data System (ADS)

    Duane, S.; Aldehaybes, M.; Bailey, M.; Lee, N. D.; Thomas, C. G.; Palmans, H.

    2012-10-01

    A new calorimeter for dosimetry in small and complex fields has been built. The device is intended for the direct determination of absorbed dose to water in moderately small fields and in composite fields such as IMRT treatments, and as a transfer instrument calibrated against existing absorbed dose standards in conventional reference conditions. The geometry, materials and mode of operation have been chosen to minimize detector perturbations when used in a water phantom, to give a reasonably isotropic response and to minimize the effects of heat transfer when the calorimeter is used in non-reference conditions in a water phantom. The size of the core is meant to meet the needs of measurement in IMRT treatments and is comparable to the size of the air cavity in a type NE2611 ionization chamber. The calorimeter may also be used for small field dosimetry. Initial measurements in reference conditions and in an IMRT head and neck plan, collapsed to gantry angle zero, have been made to estimate the thermal characteristics of the device, and to assess its performance in use. The standard deviation (estimated repeatability) of the reference absorbed dose measurements was 0.02 Gy (0.6%).

  7. Determination of neutron absorbed doses in lithium aluminates.

    PubMed

    Delfín Loya, A; Carrera, L M; Ureña-Núñez, F; Palacios, O; Bosch, P

    2003-04-01

    Lithium-based ceramics have been proposed as tritium breeders for fusion reactors. The lithium aluminate (gamma phase) seems to be thermally and structurally stable, the damages produced by neutron irradiation depend on the absorbed dose. A method based on the measurement of neutron activation of foils through neutron capture has been developed to obtain the neutron absorbed dose in lithium aluminates irradiated in the thermal column facility and in the fixed irradiation system of a Triga Mark III Nuclear Reactor. PMID:12672632

  8. Graphite calorimetry for absorbed dose measurements in heavy-ion beams

    NASA Astrophysics Data System (ADS)

    Sakama, M.; Kanai, T.; Fukumura, A.

    In order to sophisticate the radiotherapy high accuracy knowledge of the absorbed dose delivered to the patient is essential The main methods of absolute dosimetry are indicated as follows a Dosimetry by ion chamber b Fricke dosimetry and c Calorimetry The calorimetry is most direct method of dosimetry due to direct measurement of energy deposit in principle and no requirement of information of radiation fields for the calibration Many countries tend to adopt the calorimetry to determine the standard absorbed dose to water and become to be capable of deciding the absorbed dose in precision of about 0 6 for photon and electron beams Despite the recent progress of particle therapy the parameters such as w-value and stopping power ratio for ionization chambers in the particles is not obtained accurately Therefore that causes uncertainty in determination of the absolute dose For this reason we developed a graphite calorimeter to obtain high precision absorbed dose and reduce the uncertainty for various beams When the absorbed dose of 1 Gy is irradiated to the sensitive volume the temperature rise is about 1 4 milliKelvins The performance require the resolution of plus or minus 7 micro Kelvins to measure it in precision of plus or minus 0 5 The stability within several micro Kelvins per minute is necessary to obtain measurable background The miniature glass bead thermistors were embedded in the sensitive volume to perform active control of temperature The resistance change of these thermistors is approximately 0 68 Ohms and 488 micro Ohms at

  9. Neutron absorbed dose determination by calculations of recoil energy.

    PubMed

    Wrobel, F; Benabdesselam, M; Iacconi, P; Lapraz, D

    2004-01-01

    The aim of this work is to calculate the absorbed dose to matter due to neutrons in the 5-150 MeV energy range. Materials involved in the calculations are Al2O3, CaSO4 and CaS, which may be used as dosemeters and have already been studied for their luminescent properties. The absorbed dose is assumed to be mainly due to the energy deposited by the recoils. Elastic reactions are treated with the ECIS code while for the non-elastic ones, a Monte Carlo code has been developed and allowed to follow the nucleus decay and to determine its characteristics (nature and energy). Finally, the calculations show that the absorbed dose is mainly due to non-elastic process and that above 20 MeV this dose decreases slightly with the neutron energy. PMID:15353750

  10. Absorbed dose from traversing spherically symmetric, Gaussian radioactive clouds.

    PubMed

    Thompson, J M; Poston, J W

    1999-06-01

    If a large radioactive cloud is produced, sampling may require that an airplane traverse the cloud. A method to predict the absorbed dose to the aircrew from penetrating the radioactive cloud is needed. Dose rates throughout spherically symmetric Gaussian clouds of various sizes, and the absorbed doses from traversing the clouds, were calculated. Cloud size is a dominant parameter causing dose to vary by orders of magnitude for a given dose rate measured at some distance. A method to determine cloud size, based on dose rate readings at two or more distances from the cloud center, was developed. This method, however, failed to resolve the smallest cloud sizes from measurements made at 1,000 m to 2,000 m from the cloud center.

  11. Electronic compensation technique to deliver a total body dose

    NASA Astrophysics Data System (ADS)

    Lakeman, Tara E.

    Purpose: Total body irradiation (TBI) uses large parallel-opposed radiation fields to suppress the patient's immune system and eradicate the residual cancer cells in preparation of recipient for bone marrow transplant. The manual placement of lead compensators has been conventionally used to compensate for the varying thickness throughout the body in large-field TBI. The goal of this study is to pursue utilizing the modern electronic compensation technique to more accurately and efficiently deliver dose to patients in need of TBI. Method: Treatment plans utilizing the electronic compensation to deliver a total body dose were created retrospectively for patients for whom CT data had been previously acquired. Each treatment plan includes two pair of parallel opposed fields. One pair of large fields is used to encompass the majority of the patient's anatomy. The other pair are very small open fields focused only on the thin bottom portion of the patient's anatomy, which requires much less radiation than the rest of the body to reach 100% of the prescribed dose. A desirable fluence pattern was manually painted within each of the larger fields for each patient to provide a more uniform distribution. Results: Dose-volume histograms (DVH) were calculated for evaluating the electronic compensation technique. In the electronically compensated plans, the maximum body doses calculated from the DVH were reduced from the conventionally-compensated plans by an average of 15%, indicating a more uniform dose. The mean body doses calculated from the electronically compensated DVH remained comparable to that of the conventionally-compensated plans, indicating an accurate delivery of the prescription dose using electronic compensation. All calculated monitor units were within clinically acceptable limits. Conclusion: Electronic compensation technique for TBI will not increase the beam on time beyond clinically acceptable limits while it can substantially reduce the compensator setup

  12. Delivered dose estimate to standardize airway hyperresponsiveness assessment in mice.

    PubMed

    Robichaud, Annette; Fereydoonzad, Liah; Schuessler, Thomas F

    2015-04-15

    Airway hyperresponsiveness often constitutes a primary outcome in respiratory studies in mice. The procedure commonly employs aerosolized challenges, and results are typically reported in terms of bronchoconstrictor concentrations loaded into the nebulizer. Yet, because protocols frequently differ across studies, especially in terms of aerosol generation and delivery, direct study comparisons are difficult. We hypothesized that protocol variations could lead to differences in aerosol delivery efficiency and, consequently, in the dose delivered to the subject, as well as in the response. Thirteen nebulization patterns containing common protocol variations (nebulization time, duty cycle, particle size spectrum, air humidity, and/or ventilation profile) and using increasing concentrations of methacholine and broadband forced oscillations (flexiVent, SCIREQ, Montreal, Qc, Canada) were created, characterized, and studied in anesthetized naïve A/J mice. A delivered dose estimate calculated from nebulizer-, ventilator-, and subject-specific characteristics was introduced and used to account for protocol variations. Results showed that nebulization protocol variations significantly affected the fraction of aerosol reaching the subject site and the delivered dose, as well as methacholine reactivity and sensitivity in mice. From the protocol variants studied, addition of a slow deep ventilation profile during nebulization was identified as a key factor for optimization of the technique. The study also highlighted sensitivity differences within the lung, as well as the possibility that airway responses could be selectively enhanced by adequate control of nebulizer and ventilator settings. Reporting results in terms of delivered doses represents an important standardizing element for assessment of airway hyperresponsiveness in mice. PMID:25637610

  13. Absorbed dose to water reference dosimetry using solid phantoms in the context of absorbed-dose protocols

    SciTech Connect

    Seuntjens, Jan; Olivares, Marina; Evans, Michael; Podgorsak, Ervin

    2005-09-15

    For reasons of phantom material reproducibility, the absorbed dose protocols of the American Association of Physicists in Medicine (AAPM) (TG-51) and the International Atomic Energy Agency (IAEA) (TRS-398) have made the use of liquid water as a phantom material for reference dosimetry mandatory. In this work we provide a formal framework for the measurement of absorbed dose to water using ionization chambers calibrated in terms of absorbed dose to water but irradiated in solid phantoms. Such a framework is useful when there is a desire to put dose measurements using solid phantoms on an absolute basis. Putting solid phantom measurements on an absolute basis has distinct advantages in verification measurements and quality assurance. We introduce a phantom dose conversion factor that converts a measurement made in a solid phantom and analyzed using an absorbed dose calibration protocol into absorbed dose to water under reference conditions. We provide techniques to measure and calculate the dose transfer from solid phantom to water. For an Exradin A12 ionization chamber, we measured and calculated the phantom dose conversion factor for six Solid Water{sup TM} phantoms and for a single Lucite phantom for photon energies between {sup 60}Co and 18 MV photons. For Solid Water{sup TM} of certified grade, the difference between measured and calculated factors varied between 0.0% and 0.7% with the average dose conversion factor being low by 0.4% compared with the calculation whereas for Lucite, the agreement was within 0.2% for the one phantom examined. The composition of commercial plastic phantoms and their homogeneity may not always be reproducible and consistent with assumed composition. By comparing measured and calculated phantom conversion factors, our work provides methods to verify the consistency of a given plastic for the purpose of clinical reference dosimetry.

  14. Evaluation of absorbed dose in Gadolinium neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Abdullaeva, Gayane; Djuraeva, Gulnara; Kim, Andrey; Koblik, Yuriy; Kulabdullaev, Gairatulla; Rakhmonov, Turdimukhammad; Saytjanov, Shavkat

    2015-02-01

    Gadolinium neutron capture therapy (GdNCT) is used for treatment of radioresistant malignant tumors. The absorbed dose in GdNCT can be divided into four primary dose components: thermal neutron, fast neutron, photon and natural gadolinium doses. The most significant is the dose created by natural gadolinium. The amount of gadolinium at the irradiated region is changeable and depends on the gadolinium delivery agent and on the structure of the location where the agent is injected. To de- fine the time dependence of the gadolinium concentration ρ(t) in the irradiated region the pharmacokinetics of gadolinium delivery agent (Magnevist) was studied at intratumoral injection in mice and intramuscular injection in rats. A polynomial approximation was applied to the experimental data and the influence of ρ(t) on the relative change of the absorbed dose of gadolinium was studied.

  15. 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

  16. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 MgY for the parotid gland, 0.15 MgY for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field.

  17. Space radiation absorbed dose distribution in a human phantom.

    PubMed

    Badhwar, G D; Atwell, W; Badavi, F F; Yang, T C; Cleghorn, T F

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  18. Space radiation absorbed dose distribution in a human phantom

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  19. Space radiation absorbed dose distribution in a human phantom.

    PubMed

    Badhwar, G D; Atwell, W; Badavi, F F; Yang, T C; Cleghorn, T F

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  20. Developability assessment of clinical drug products with maximum absorbable doses.

    PubMed

    Ding, Xuan; Rose, John P; Van Gelder, Jan

    2012-05-10

    Maximum absorbable dose refers to the maximum amount of an orally administered drug that can be absorbed in the gastrointestinal tract. Maximum absorbable dose, or D(abs), has proved to be an important parameter for quantifying the absorption potential of drug candidates. The purpose of this work is to validate the use of D(abs) in a developability assessment context, and to establish appropriate protocol and interpretation criteria for this application. Three methods for calculating D(abs) were compared by assessing how well the methods predicted the absorption limit for a set of real clinical candidates. D(abs) was calculated for these clinical candidates by means of a simple equation and two computer simulation programs, GastroPlus and an program developed at Eli Lilly and Company. Results from single dose escalation studies in Phase I clinical trials were analyzed to identify the maximum absorbable doses for these compounds. Compared to the clinical results, the equation and both simulation programs provide conservative estimates of D(abs), but in general D(abs) from the computer simulations are more accurate, which may find obvious advantage for the simulations in developability assessment. Computer simulations also revealed the complex behavior associated with absorption saturation and suggested in most cases that the D(abs) limit is not likely to be achieved in a typical clinical dose range. On the basis of the validation findings, an approach is proposed for assessing absorption potential, and best practices are discussed for the use of D(abs) estimates to inform clinical formulation development strategies.

  1. Evaluation of lens absorbed dose with Cone Beam IGRT procedures.

    PubMed

    Palomo, R; Pujades, M C; Gimeno-Olmos, J; Carmona, V; Lliso, F; Candela-Juan, C; Vijande, J; Ballester, F; Perez-Calatayud, J

    2015-12-01

    The purpose of this work is to evaluate the absorbed dose to the eye lenses due to the cone beam computed tomography (CBCT) system used to accurately position the patient during head-and-neck image guided procedures. The on-board imaging (OBI) systems (v.1.5) of Clinac iX and TrueBeam (Varian) accelerators were used to evaluate the imparted dose to the eye lenses and some additional points of the head. All CBCT scans were acquired with the Standard-Dose Head protocol from Varian. Doses were measured using thermoluminescence dosimeters (TLDs) placed in an anthropomorphic phantom. TLDs were calibrated at the beam quality used to reduce their energy dependence. Average dose to the lens due to the OBI systems of the Clinac iX and the TrueBeam were 0.71  ±  0.07 mGy/CBCT and 0.70  ±  0.08 mGy/CBCT, respectively. The extra absorbed dose received by the eye lenses due to one CBCT acquisition with the studied protocol is far below the 500 mGy threshold established by ICRP for cataract formation (ICRP 2011 Statement on Tissue Reactions). However, the incremental effect of several CBCT acquisitions during the whole treatment should be taken into account. PMID:26457404

  2. Absorbed dose assessment in newborns during x-ray examinations

    NASA Astrophysics Data System (ADS)

    Taipe, Patricia K.; Berrocal, Mariella J.; Carita, Raúl F.

    2012-02-01

    Often a newborn presents breathing problems during the early days of life, i.e. bronchopneumonia, wich are caused in most of cases, by aspirating a mixture of meconium and amniotic fluid. In these cases, it is necessary to make use of a radiograph, requested by the physician to reach a diagnosis. This paper seeks to evaluate the absorbed doses in neonates undergoing a radiograph. For this reason we try to simulate the real conditions in a X-ray room from Lima hospitals. With this finality we perform a simulation made according a questionnaire related to technical data of X-ray equipment, distance between the source and the neonate, and its position to be irradiated. The information obtained has been used to determine the absorbed dose by infants, using the MCNP code. Finally, the results are compared with reference values of international health agencies.

  3. SU-FF-T-390: In-Vivo Prostate Brachytherapy Absorbed Dose Measurements

    SciTech Connect

    Gueye, Paul; Velasco, Carlos; Keppel, Cynthia; Murphy, B; Sinesi, C

    2009-06-01

    Purpose: In-vivo prostate brachytherapy absorbed dosimetrydetector using scintillating fibers. Method and Materials: Five pairs of 85.5 {+-} 0.05 cm long blue shifted scintillating fibers (model BCF-10) with 1 mm{sup 2} cross sectional area were placed in a mixture of gelatin (368.6 {+-} 0.5 grams) and water (3.78 {+-} 0.025 liters) to measured the absorbed dose delivered by a 12 Ci {sup 192}Ir HDR source. The fibers were held by a 7 x 7 cm{sup 2} template grid and optically connected to a 16-channel multianode photomultiplier tube (Hamamatsu, model H6568). Each pair consisted of one fiber 4 mm shorter than the other one to extract the dose by the subtraction method. A dose atlas was used for radiation delivered to the phantom. The plans followed delivered 5 and 7 Gy to a point located 2.0 centimeters away from the central dwelling positions. A total of 32 data points were acquired in a plan to assess the linearity and reproducibility of the measurements.Results: Reproducibility of the data was found to be within 5% and the overall accuracy of the system estimated to be {+-}5.5%. The linearity of the data for all 7 measureddose values (ranging from 0.6 to 7 Gy), gives a slope of 312 counts/Gy with a 1.4% relative deviation. Conclusion: This work indicates the possibility of measuring in real-time the dose effectively delivered to a biological system during prostate brachytherapy treatments. The availability of commercially thin (150 {micro}m) scintillating fibers opens the capability of using such system during clinical treatments (by embedding the fibers within the catheters) with the advantage of performing real-time adjustment of the dose delivery.

  4. Reduction of absorbed doses in radiography of the facial skeleton

    SciTech Connect

    Julin, P.; Kraepelien, T.

    1984-11-01

    Radiation absorbed doses from radiography of the paranasal sinuses and the facial skeleton were measured with thermoluminescent dosimeters (TLD) on a phantom head using high-sensitivity screens in an Orbix stand. The entrance doses to the skin of the head ranged from 0.31 to 2.9 mGy per exposure. The absorbed dose from a full series of sinus exposures averaged 0.33 mGy for the oral mucous membrane, 0.33 mGy for the maxillary sinus mucous membrane, 0.11 mGy for the parotid gland, 0.15 mGy for the submandibular gland, 0.61 mGy for the eye lens, and 0.75 mGy for the thyroid gland region. A leaded soft collar adapted to the thyroid region reduced the thyroid doses by more than one order of magnitude, but also reduced the image field. The mean energy imparted from a full series of paranasal sinus projections was 4.8 mJ and from a total series of the facial skeleton, 7.9 mJ.

  5. The absorbed dose to blood from blood-borne activity

    NASA Astrophysics Data System (ADS)

    Hänscheid, H.; Fernández, M.; Lassmann, M.

    2015-01-01

    The radiation absorbed dose to blood and organs from activity in the blood is relevant for nuclear medicine dosimetry and for research in biodosimetry. The present study provides coefficients for the average absorbed dose rates to the blood from blood-borne activity for radionuclides frequently used in targeted radiotherapy and in PET diagnostics. The results were deduced from published data for vessel radius-dependent dose rate coefficients and reasonable assumptions on the blood-volume distribution as a function of the vessel radius. Different parts of the circulatory system were analyzed separately. Vessel size information for heart chambers, aorta, vena cava, pulmonary artery, and capillaries was taken from published results of morphometric measurements. The remaining blood not contained in the mentioned vessels was assumed to reside in fractal-like vascular trees, the smallest branches of which are the arterioles or venules. The applied vessel size distribution is consistent with recommendations of the ICRP on the blood-volume distribution in the human. The resulting average absorbed dose rates to the blood per nuclear disintegration per milliliter (ml) of blood are (in 10-11 Gy·s-1·Bq-1·ml) Y-90: 5.58, I-131: 2.49, Lu-177: 1.72, Sm-153: 2.97, Tc-99m: 0.366, C-11: 4.56, F-18: 3.61, Ga-68: 5.94, I-124: 2.55. Photon radiation contributes 1.1-1.2·10-11 Gy·s-1·Bq-1·ml to the total dose rate for positron emitters but significantly less for the other nuclides. Blood self-absorption of the energy emitted by ß-particles in the whole blood ranges from 37% for Y-90 to 80% for Tc-99m. The correspondent values in vascular trees, which are important for the absorbed dose to organs, range from 30% for Y-90 to 82% for Tc-99m.

  6. Radiation environments and absorbed dose estimations on manned space missions

    NASA Astrophysics Data System (ADS)

    Curtis, S. B.; Atwell, W.; Beever, R.; Hardy, A.

    In order to make an assessment of radiation risk during manned missions in space, it is necessary first to have as accurate an estimation as possible of the radiation environment within the spacecraft to which the astronauts will be exposed. Then, with this knowledge and the inclusion of body self-shielding, estimations can be made of absorbed doses for various body organs (skin, eye, blood-forming organs, etc.). A review is presented of our present knowledge of the radiation environments and absorbed doses expected for several space mission scenarios selected for our development of the new radiation protection guidelines. The scenarios selected are a 90-day mission at an altitude (450 km) and orbital inclinations (28.5°, 57° and 90°) appropriate for NASA's Space Station, a 15-day sortie to geosynchronous orbit and a 90-day lunar mission. All scenarios chosen yielded dose equivalents between five and ten rem to the blood forming organs if no large solar particle event were encountered. Such particle events could add considerable exposure particularly to the skin and eye for all scenarios except the one at 28.5° orbital inclination.

  7. Strontium-89 therapy: measurement of absorbed dose to skeletal metastases.

    PubMed

    Blake, G M; Zivanovic, M A; Blaquiere, R M; Fine, D R; McEwan, A J; Ackery, D M

    1988-04-01

    We report measurements of absorbed dose to vertebral metastases in ten patients referred for 89Sr therapy for disseminated prostatic carcinoma. Patients received a tracer dose of 85Sr at the time of 89Sr treatment and metastatic strontium retention was monitored scintigraphically for 6 mo. Metastatic 85Sr activity corrected for tissue attenuation was measured using the conjugate view principle, with special care taken to eliminate errors due to the selection of the metastatic region of interest. Metastatic volume was determined from high resolution CT images, and density inferred from Hounsfield number using the QCT bone mineral calibration of Genant and Cann. The mean absorbed dose was 850 rad/mCi (23 cGy/MBq) with a range from 220-2260 rad/mCi (6 to 61 cGy/MBq). The wide range found was consistent with the variation expected to arise due to differences in strontium renal plasma clearance (range 0.1-11.81/day) and extent of skeletal metastatic disease (varying from two small metastases to a superscan on [99mTc]MDP images) among the patients studied. PMID:3351609

  8. 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.

  9. Delivered dialysis dose is suboptimal in hospitalized patients.

    PubMed

    Obialo, C I; Hernandez, B; Carter, D

    1998-01-01

    Underdialyzed patients have high hospitalization and mortality rates. It is unclear if such patients receive adequate dialysis during hospitalization. In this cross-sectional study, we evaluated single treatment delivered dialysis dose during hospitalization and compared this to the dosage received at the free-standing outpatient clinics in the same patients. Eighty-four patients (54% male) aged 23-63 years (means +/- SD 55.5 +/- 14.6) who have been on dialysis for at least 3 months were evaluated. Hypertension and diabetes were the most common diagnoses, while thrombosed graft or fistula accounted for 40% of admissions. The mean dialysis treatment time (Td) was 30 min longer in the outpatient (OP) setting than the hospital (H): 3.6 +/- 0.3 vs. 3.1 +/- 0.2 h (p < 0.0001). Attained blood flow (QB) was 15% greater in the OP than H: 394 +/- 40 vs. 331 +/- 54 ml/min (p < 0.0001). The Kt/V was analyzed in 49 of 84 patients; the OP Kt/V was 20% greater than the H Kt/V: 1.38 +/- 0.2 vs. 1.11 +/- 0.1 (p < 0.0001). A further breakdown of H Kt/V according to access and membrane types showed that patients with functional grafts/fistula had a higher Kt/V than those with temporary accesses 1.14 +/- 0.1 vs. 1.07 +/- 0.1 (p = 0.01). We conclude that hospitalized patients receive suboptimal dialysis dose, this could have a negative impact on survival if hospitalization is recurrent and prolonged. Kinetic modeling should be routinely performed in such patients and Td should be increased in patients with temporary accesses. PMID:9845829

  10. Efficacy of photothermal ablation using intravenously delivered NIR-absorbing nanorods in colon cancer

    NASA Astrophysics Data System (ADS)

    Goodrich, Glenn P.; Payne, J. Donald; Sharp, Kelly; Bao, LiLi; Sang, Kristina L.

    2009-02-01

    The use of near-infrared absorbing nanoparticles recently has been proposed for the minimally invasive photothermal ablation of solid tumors, and this approach currently is being investigated in the clinic. One class of nanoparticles, gold nanorods, has been investigated for the ablation of various cancer types using both direct injection and systemic delivery. Here we investigate the photothermal ablation of colon cancer in an animal model using intravenously delivered gold nanorods. Nanorods with an aspect ratio of ~3.2 and an extinction peak of 774 nm were PEGylated, suspended in an isotonic solution, and infused into the tail vein of BALB/c mice bearing subcutaneous CT26.wt murine colon cancer tumors. After 24 hrs, an isotropic laser fiber was inserted through a small incision in the skin to a point proximate to and beneath the tumor. The area was illuminated with 3.5 W average power for 3 minutes. Control groups consisted of laser-only, nanorod-only and untreated tumored animals. The survival of the animals receiving nanorod-based photothermal ablation was statistically longer than the control groups with >44% complete response. This work demonstrates the promise of systemically delivering nanoparticles to tumors for thermal ablation

  11. SU-E-I-85: Absorbed Dose Estimation for a Commercially Available MicroCT Scanner

    SciTech Connect

    Lau, A; Ahmad, S; Chen, Y; Ren, L; Liu, H; Yang, K

    2015-06-15

    Purpose: To quantify the simulated absorbed dose delivered for a typical scan from a commercially available microCT scanner in order to aid in the dose estimation. Methods: The simulations were conducted using the Geant4 Monte Carlo Toolkit (version 10) with the standard electromagnetic classes. The Quantum FX microCT scanner (PerkinElmer, Waltham, MA) was modeled incorporating the energy fluence and angular distributions of generated photons, spatial dimensions of nominal source-to-object and source-to-detector distances. The energy distribution was measured using a spectrometer (X-123CdTe, Amptek Inc., Bedford, USA) with a 300 angular spread from the source for the 90 kVp X-ray beams with no additional filtration. The nominal distances from the source to object consisted of three setups: 154.0 mm, 104.0 mm, and 51.96 mm. Our simulations recorded the dose absorbed in a cylindrical phantom of PMMA with a fixed length of 2 cm and varying radii (10, 20, 30 and 40 mm) using 100 million incident photons. The averaged absorbed dose in the object was then quantified for all setups. An exposure measurement of 417 mR was taken using a Radcal 9095 system utilizing 10×9–180 ion chamber with the given technique of 90 kVp, 63 μA, and 12 s. The exposure rate was also simulated with same setup to calculate the conversion factor of the beam current and the number of incident photons. Results: For a typical cone-beam scan with non-filtered 90kVp, the dose coefficients (the absorbed dose per mAs) were 2.614, 2.549 and 2.467 μGy/mAs under source to object distance of 104 mm for the object diameters of 10 mm, 20 mm and 30 mm, respectively. Conclusion: A look-up table was developed where an investigator can estimate the delivered dose using this particular microCT given the scanning protocol (kVp and mAs) as well as the size of the scanned object.

  12. Absorbed dose to water: Standards and traceability for radiation oncology

    SciTech Connect

    Almond, P.R.

    1995-12-31

    Although the need for appropriate quantities and units for ionizing radiation has existed since shortly after discovery of X-rays, the quantities and units in general use today were not completely formalized until about 15 years ago. The development of appropriate national and international standards have also been ongoing. For many years the quantity, exposure, measured in units of roentgen was the national standard and they were also the quantity and units in which radiotherapy was described. With the introduction of megavoltage X-ray and electron-beam equipment and the adoption of the quantity {open_quotes}absorbed-dose{close_quotes} measured in units of rad (or gray) different approaches to calibrating these beams were needed. This was especially the case since the national standard in terms of exposure at a maximum photon energy for {sup 60}Co gamma rays was only available. Since the late 1960s various machine calibration protocols have been published. These protocols have to accommodate changes in modality, energy, quantities and units between the national standard and the user. Because of this, a new definition of traceability is proposed to accommodate the present system. By recording all intercomparisons and parameters used, an auditable calibration chain can be maintained. Even with the introduction of calibration protocols based upon national absorbed dose standards, the proposed traceability definition will still be needed.

  13. Maximizing the biological effect of proton dose delivered with scanned beams via inhomogeneous daily dose distributions

    SciTech Connect

    Zeng Chuan; Giantsoudi, Drosoula; Grassberger, Clemens; Goldberg, Saveli; Niemierko, Andrzej; Paganetti, Harald; Efstathiou, Jason A.; Trofimov, Alexei

    2013-05-15

    Purpose: Biological effect of radiation can be enhanced with hypofractionation, localized dose escalation, and, in particle therapy, with optimized distribution of linear energy transfer (LET). The authors describe a method to construct inhomogeneous fractional dose (IFD) distributions, and evaluate the potential gain in the therapeutic effect from their delivery in proton therapy delivered by pencil beam scanning. Methods: For 13 cases of prostate cancer, the authors considered hypofractionated courses of 60 Gy delivered in 20 fractions. (All doses denoted in Gy include the proton's mean relative biological effectiveness (RBE) of 1.1.) Two types of plans were optimized using two opposed lateral beams to deliver a uniform dose of 3 Gy per fraction to the target by scanning: (1) in conventional full-target plans (FTP), each beam irradiated the entire gland, (2) in split-target plans (STP), beams irradiated only the respective proximal hemispheres (prostate split sagittally). Inverse planning yielded intensity maps, in which discrete position control points of the scanned beam (spots) were assigned optimized intensity values. FTP plans preferentially required a higher intensity of spots in the distal part of the target, while STP, by design, employed proximal spots. To evaluate the utility of IFD delivery, IFD plans were generated by rearranging the spot intensities from FTP or STP intensity maps, separately as well as combined using a variety of mixing weights. IFD courses were designed so that, in alternating fractions, one of the hemispheres of the prostate would receive a dose boost and the other receive a lower dose, while the total physical dose from the IFD course was roughly uniform across the prostate. IFD plans were normalized so that the equivalent uniform dose (EUD) of rectum and bladder did not increase, compared to the baseline FTP plan, which irradiated the prostate uniformly in every fraction. An EUD-based model was then applied to estimate tumor

  14. 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.

  15. Absorbed dose and LET spectra measurements on LDEF

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Csige, I.; Frank, A. L.; Benton, E. R.; Frigo, L. A.; Parnell, T. A.; Watts, J.; Harmon, A.

    1995-01-01

    Total absorbed doses measured with TLD's, linear energy transfer (LET) spectra measured with plastic track detectors, and low energy neutrons measured on LDEF have been compared with model calculations. The total absorbed doses measured in TLD's were higher than predicted in the calculations of Armstrong et al. and differ from the calculations of Atwell et al. LDEF LET spectra are dependent on detector orientation, shielding and experiment location. These factors need to be taken into account when modeling the LDEF LET spectra. LET spectra measured with plastic nuclear track detectors (PNTD's) also deviate significantly from calculations especially for high LET particles (LET(sub infinity) H2O greater than 100keV/micron). Modeling efforts to date do not include the contribution of proton induced secondaries. Analysis of polycarbonate PNTD's from the West-side of LDEF has revealed a very high fluence of tracks (greater than 1 x 10(exp 7) tracks/cm(exp 2) under 2 gm/cm(exp 2) shielding). Fluence drops off rapidly as shielding depth increases. Tracks only form in the region of the detector closest to the surface, not in the bulk of the detector. To date no adequate explanation for this observation has been found. We plan to measure range distribution of very high LET (LET (sub infinity) H2O greater than 500 keV/micron) secondary particles produced in silicon wafer by high energy primary cosmic ray particles. Refinements of experimental techniques and model calculations are being carried out in order to understand existing discrepancies between experimental measurements and calculations.

  16. Angular absorbed dose dependence of internal radiation-generating devices in radiotherapy.

    PubMed

    Bevelacqua, J J

    2012-01-01

    The angular dependence of the absorbed dose from internal radiation-generating devices located within a tumor mass is investigated. Given the systematics of proton and heavy-ion differential scattering cross sections, candidate internal radiation-generating devices will have a relatively constant absorbed dose output beyond a critical angle. Inside this angle, the absorbed dose output is suppressed because elastic and inelastic differential cross sections are peaked in the beam direction. This peaking increases in severity as the particle energy increases and suggests internal radiation-generating devices must have a limited rotation capability to compensate for the depression in the absorbed dose for angles near the beam direction.

  17. Nanoparticle-based cancer treatment: can delivered dose and biological dose be reliably modeled and quantified?

    NASA Astrophysics Data System (ADS)

    Hoopes, P. Jack; Petryk, Alicia A.; Giustini, Andrew J.; Stigliano, Robert V.; D'Angelo, Robert N.; Tate, Jennifer A.; Cassim, Shiraz M.; Foreman, Allan; Bischof, John C.; Pearce, John A.; Ryan, Thomas

    2011-03-01

    Essential developments in the reliable and effective use of heat in medicine include: 1) the ability to model energy deposition and the resulting thermal distribution and tissue damage (Arrhenius models) over time in 3D, 2) the development of non-invasive thermometry and imaging for tissue damage monitoring, and 3) the development of clinically relevant algorithms for accurate prediction of the biological effect resulting from a delivered thermal dose in mammalian cells, tissues, and organs. The accuracy and usefulness of this information varies with the type of thermal treatment, sensitivity and accuracy of tissue assessment, and volume, shape, and heterogeneity of the tumor target and normal tissue. That said, without the development of an algorithm that has allowed the comparison and prediction of the effects of hyperthermia in a wide variety of tumor and normal tissues and settings (cumulative equivalent minutes/ CEM), hyperthermia would never have achieved clinical relevance. A new hyperthermia technology, magnetic nanoparticle-based hyperthermia (mNPH), has distinct advantages over the previous techniques: the ability to target the heat to individual cancer cells (with a nontoxic nanoparticle), and to excite the nanoparticles noninvasively with a noninjurious magnetic field, thus sparing associated normal cells and greatly improving the therapeutic ratio. As such, this modality has great potential as a primary and adjuvant cancer therapy. Although the targeted and safe nature of the noninvasive external activation (hysteretic heating) are a tremendous asset, the large number of therapy based variables and the lack of an accurate and useful method for predicting, assessing and quantifying mNP dose and treatment effect is a major obstacle to moving the technology into routine clinical practice. Among other parameters, mNPH will require the accurate determination of specific nanoparticle heating capability, the total nanoparticle content and biodistribution in

  18. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1).

  19. Absorbed dose rate in air in metropolitan Tokyo before the Fukushima Daiichi Nuclear Power Plant accident.

    PubMed

    Inoue, K; Hosoda, M; Fukushi, M; Furukawa, M; Tokonami, S

    2015-11-01

    The monitoring of absorbed dose rate in air has been carried out continually at various locations in metropolitan Tokyo after the accident of the Fukushima Daiichi Nuclear Power Plant. While the data obtained before the accident are needed to more accurately assess the effects of radionuclide contamination from the accident, detailed data for metropolitan Tokyo obtained before the accident have not been reported. A car-borne survey of the absorbed dose rate in air in metropolitan Tokyo was carried out during August to September 2003. The average absorbed dose rate in air in metropolitan Tokyo was 49±6 nGy h(-1). The absorbed dose rate in air in western Tokyo was higher compared with that in central Tokyo. Here, if the absorbed dose rate indoors in Tokyo is equivalent to that outdoors, the annual effective dose would be calculated as 0.32 mSv y(-1). PMID:25944962

  20. Uncertainty analysis for absorbed dose from a brain receptor imaging agent

    SciTech Connect

    Aydogan, B.; Miller, L.F.; Sparks, R.B.; Stubbs, J.B.

    1999-01-01

    Absorbed dose estimates are known to contain uncertainties. A recent literature search indicates that prior to this study no rigorous investigation of uncertainty associated with absorbed dose has been undertaken. A method of uncertainty analysis for absorbed dose calculations has been developed and implemented for the brain receptor imaging agent {sup 123}I-IPT. The two major sources of uncertainty considered were the uncertainty associated with the determination of residence time and that associated with the determination of the S values. There are many sources of uncertainty in the determination of the S values, but only the inter-patient organ mass variation was considered in this work. The absorbed dose uncertainties were determined for lung, liver, heart and brain. Ninety-five percent confidence intervals of the organ absorbed dose distributions for each patient and for a seven-patient population group were determined by the ``Latin Hypercube Sampling`` method. For an individual patient, the upper bound of the 95% confidence interval of the absorbed dose was found to be about 2.5 times larger than the estimated mean absorbed dose. For the seven-patient population the upper bound of the 95% confidence interval of the absorbed dose distribution was around 45% more than the estimated population mean. For example, the 95% confidence interval of the population liver dose distribution was found to be between 1.49E+0.7 Gy/MBq and 4.65E+07 Gy/MBq with a mean of 2.52E+07 Gy/MBq. This study concluded that patients in a population receiving {sup 123}I-IPT could receive absorbed doses as much as twice as large as the standard estimated absorbed dose due to these uncertainties.

  1. Measured absorbed dose rates from semi-infinite hemispherical volumes of 133Xe.

    PubMed

    Munyon, W J; Barber, D E; Howley, J R

    1986-07-01

    Surface absorbed dose rates from different hemispheric volumes of 133Xe have been measured directly with an extrapolation chamber. The results indicate that a linear relationship exists between the radius of the cloud volume and the surface absorbed dose rate for radii between 0 and 23 cm. If cloud volumes with radii larger than 23 cm are taken to be infinite with respect to the range of the charged particles emitted, the absorbed dose rate calculated based on that assumption will be within the uncertainty of any measurement of absorbed dose rate that might be made. For hemispheric volumes having radii less than or equal to 23 cm, the surface absorbed dose rate in tissue-equivalent material, in mGy h-1, is approximated (+/- 20%) by the product of [1.30 mGy h-1 cm-1 kBq-1 cm3] X [cloud radius, cm] X [cloud activity concentration, kBq cm-3].

  2. Experimental evaluation of actual delivered dose using mega-voltage cone-beam CT and direct point dose measurement

    SciTech Connect

    Matsubara, Kana; Kohno, Ryosuke; Nishioka, Shie; Shibuya, Toshiyuki; Ariji, Takaki; Akimoto, Tetsuo; Saitoh, Hidetoshi

    2013-07-01

    Radiation therapy in patients is planned by using computed tomography (CT) images acquired before start of the treatment course. Here, tumor shrinkage or weight loss or both, which are common during the treatment course for patients with head-and-neck (H and N) cancer, causes unexpected differences from the plan, as well as dose uncertainty with the daily positional error of patients. For accurate clinical evaluation, it is essential to identify these anatomical changes and daily positional errors, as well as consequent dosimetric changes. To evaluate the actual delivered dose, the authors proposed direct dose measurement and dose calculation with mega-voltage cone-beam CT (MVCBCT). The purpose of the present study was to experimentally evaluate dose calculation by MVCBCT. Furthermore, actual delivered dose was evaluated directly with accurate phantom setup. Because MVCBCT has CT-number variation, even when the analyzed object has a uniform density, a specific and simple CT-number correction method was developed and applied for the H and N site of a RANDO phantom. Dose distributions were calculated with the corrected MVCBCT images of a cylindrical polymethyl methacrylate phantom. Treatment processes from planning to beam delivery were performed for the H and N site of the RANDO phantom. The image-guided radiation therapy procedure was utilized for the phantom setup to improve measurement reliability. The calculated dose in the RANDO phantom was compared to the measured dose obtained by metal-oxide-semiconductor field-effect transistor detectors. In the polymethyl methacrylate phantom, the calculated and measured doses agreed within about +3%. In the RANDO phantom, the dose difference was less than +5%. The calculated dose based on simulation-CT agreed with the measured dose within±3%, even in the region with a high dose gradient. The actual delivered dose was successfully determined by dose calculation with MVCBCT, and the point dose measurement with the image

  3. Simultaneous measurements of absorbed dose and linear energy transfer in therapeutic proton beams.

    PubMed

    Granville, Dal A; Sahoo, Narayan; Sawakuchi, Gabriel O

    2016-02-21

    The biological response resulting from proton therapy depends on both the absorbed dose in the irradiated tissue and the linear energy transfer (LET) of the beam. Currently, optimization of proton therapy treatment plans is based only on absorbed dose. However, recent advances in proton therapy delivery have made it possible to vary the LET distribution for potential therapeutic gain, leading to investigations of using LET as an additional parameter in plan optimization. Having a method to measure and verify both absorbed dose and LET as part of a quality assurance program would be ideal for the safe delivery of such plans. Here we demonstrated the potential of an optically stimulated luminescence (OSL) technique to simultaneously measure absorbed dose and LET. We calibrated the ratio of ultraviolet (UV) to blue emission intensities from Al2O3:C OSL detectors as a function of LET to facilitate LET measurements. We also calibrated the intensity of the blue OSL emission for absorbed dose measurements and introduced a technique to correct for the LET-dependent dose response of OSL detectors exposed to therapeutic proton beams. We demonstrated the potential of our OSL technique by using it to measure LET and absorbed dose under new irradiation conditions, including patient-specific proton therapy treatment plans. In the beams investigated, we found the OSL technique to measure dose-weighted LET within 7.9% of Monte Carlo-simulated values and absorbed dose within 2.5% of ionization chamber measurements.

  4. Simultaneous measurements of absorbed dose and linear energy transfer in therapeutic proton beams.

    PubMed

    Granville, Dal A; Sahoo, Narayan; Sawakuchi, Gabriel O

    2016-02-21

    The biological response resulting from proton therapy depends on both the absorbed dose in the irradiated tissue and the linear energy transfer (LET) of the beam. Currently, optimization of proton therapy treatment plans is based only on absorbed dose. However, recent advances in proton therapy delivery have made it possible to vary the LET distribution for potential therapeutic gain, leading to investigations of using LET as an additional parameter in plan optimization. Having a method to measure and verify both absorbed dose and LET as part of a quality assurance program would be ideal for the safe delivery of such plans. Here we demonstrated the potential of an optically stimulated luminescence (OSL) technique to simultaneously measure absorbed dose and LET. We calibrated the ratio of ultraviolet (UV) to blue emission intensities from Al2O3:C OSL detectors as a function of LET to facilitate LET measurements. We also calibrated the intensity of the blue OSL emission for absorbed dose measurements and introduced a technique to correct for the LET-dependent dose response of OSL detectors exposed to therapeutic proton beams. We demonstrated the potential of our OSL technique by using it to measure LET and absorbed dose under new irradiation conditions, including patient-specific proton therapy treatment plans. In the beams investigated, we found the OSL technique to measure dose-weighted LET within 7.9% of Monte Carlo-simulated values and absorbed dose within 2.5% of ionization chamber measurements. PMID:26859539

  5. Direct absorbed dose to water determination based on water calorimetry in scanning proton beam delivery

    SciTech Connect

    Sarfehnia, A.; Clasie, B.; Chung, E.; Lu, H. M.; Flanz, J.; Cascio, E.; Engelsman, M.; Paganetti, H.; Seuntjens, J.

    2010-07-15

    Purpose: The aim of this manuscript is to describe the direct measurement of absolute absorbed dose to water in a scanned proton radiotherapy beam using a water calorimeter primary standard. Methods: The McGill water calorimeter, which has been validated in photon and electron beams as well as in HDR {sup 192}Ir brachytherapy, was used to measure the absorbed dose to water in double scattering and scanning proton irradiations. The measurements were made at the Massachusetts General Hospital proton radiotherapy facility. The correction factors in water calorimetry were numerically calculated and various parameters affecting their magnitude and uncertainty were studied. The absorbed dose to water was compared to that obtained using an Exradin T1 Chamber based on the IAEA TRS-398 protocol. Results: The overall 1-sigma uncertainty on absorbed dose to water amounts to 0.4% and 0.6% in scattered and scanned proton water calorimetry, respectively. This compares to an overall uncertainty of 1.9% for currently accepted IAEA TRS-398 reference absorbed dose measurement protocol. The absorbed dose from water calorimetry agrees with the results from TRS-398 well to within 1-sigma uncertainty. Conclusions: This work demonstrates that a primary absorbed dose standard based on water calorimetry is feasible in scattered and scanned proton beams.

  6. The changes in optical absorbance of ZrO2 thin film with the rise of the absorbed dose

    NASA Astrophysics Data System (ADS)

    Abayli, D.; Baydogan, N.

    2016-03-01

    In this study, zirconium oxide (ZrO2) thin film samples prepared by sol-gel method were irradiated using Co-60 radioisotope as gamma source. Then, it was investigated the ionizing effect on optical properties of ZrO2 thin film samples with the rise of the absorbed dose. The changes in the optical absorbance of ZrO2 thin films were determined by using optical transmittance and the reflectance measurements in the range between 190 - 1100 nm obtained from PG Instruments T80 UV-Vis spectrophotometer.

  7. 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.

  8. SU-E-J-21: Advantages of Ultra Fast Radiation Dose Delivering

    SciTech Connect

    Feng, Y

    2014-06-01

    Purpose: For delivering conformed dose to a moving tumor and sparing normal tissue, we presented an innovation that was combined a linear accelerator and a storage ring to generate ultra high dose rate. This innovation allows delivering prescribed dose to a moving target in such a short time period, for an example 0.1 second, during which the displacement of the target could be ignored. Methods: The advantages of this approach were evaluated based on normal tissue sparing, feasibility, accuracy, and time saving in clinical treatment. The target volume reduction with this innovation approach was demonstrated by analyzing the values of GTVs, ITVs, and PTVs obtained from 15 patients who had been diagnosed with malignant neoplasm of lung and treated with SBRT. The processes of SBRT treatment were investigated and advantages of this innovation in improving SBRT lung treatment were evaluated. Results: With the ultra-high dose rate, the target volumes could be reduced by ∼30% to 50%. The innovation combining with IGRT technique could deliver prescribed dose to moving target accurately with simpler procedures than that of adaptive approach. This new approach could reduce the time of guiding treatment by many times. The new technique make a new strategy became feasible that was to deliver the dose to a target when it moved to a desirable location, such as away from critical organs. Conclusion: Combining with IGRT technique, this innovation could significantly improve the accuracy to deliver dose to moving targets with a shorter time than conventional techniques. The innovation opens a door for new strategies to deliver dose to moving targets.

  9. Secondary neutron dose measurement for proton eye treatment using an eye snout with a borated neutron absorber

    PubMed Central

    2013-01-01

    Background We measured and assessed ways to reduce the secondary neutron dose from a system for proton eye treatment. Methods Proton beams of 60.30 MeV were delivered through an eye-treatment snout in passive scattering mode. Allyl diglycol carbonate (CR-39) etch detectors were used to measure the neutron dose in the external field at 0.00, 1.64, and 6.00 cm depths in a water phantom. Secondary neutron doses were measured and compared between those with and without a high-hydrogen–boron-containing block. In addition, the neutron energy and vertices distribution were obtained by using a Geant4 Monte Carlo simulation. Results The ratio of the maximum neutron dose equivalent to the proton absorbed dose (H(10)/D) at 2.00 cm from the beam field edge was 8.79 ± 1.28 mSv/Gy. The ratio of the neutron dose equivalent to the proton absorbed dose with and without a high hydrogen-boron containing block was 0.63 ± 0.06 to 1.15 ± 0.13 mSv/Gy at 2.00 cm from the edge of the field at depths of 0.00, 1.64, and 6.00 cm. Conclusions We found that the out-of-field secondary neutron dose in proton eye treatment with an eye snout is relatively small, and it can be further reduced by installing a borated neutron absorbing material. PMID:23866307

  10. Preliminary in vivo studies on the osteogenic potential of bone morphogenetic proteins delivered from an absorbable puttylike polymer matrix.

    PubMed

    Andriano, K P; Chandrashekar, B; McEnery, K; Dunn, R L; Moyer, K; Balliu, C M; Holland, K M; Garrett, S; Huffer, W E

    2000-01-01

    This article describes preliminary in vivo studies evaluating the osteogeneic potential of bone morphogenetic proteins (BMPs) delivered from an absorbable puttylike polymer matrix. In the first study, bovine-derived bone morphogenetic proteins were incorporated in an polymer matrix consisting of 50:50 poly(DL-lactide-co-glycolide) dissolved in N-methyl-2-pyrrolidone. The matrix was implanted in an 8 mm critical-size calvarial defect created in the skull of adult Sprague-Dawley rats (n = 5 per treatment group). After 28 days, the implant sites were removed and examined for new bone formation, polymer degradation, and tissue reaction. Gamma-irradiated polymer matrices appeared to give more bone formation than nonirradiated samples (histological analysis; 2. 76 + 1.34 mm(2) of bone versus 1.30 + 0.90 mm(2) of bone, respectively and x-ray analysis; 27.2 + 15.9 mm(2) of bone versus 20. 7 + 16.7 mm(2) of bone, respectively) and less residual polymer (0.0 + 0.0 versus 0.2 + 0.4, respectively). The polymer implants with bone morphogenetic protein also gave less inflammatory response than the polymer controls (gamma irradiated polymer/BMP = 1.8 + 0.4 and nonirradiated polymer/BMP = 1.2 + 0.4 versus polymer only = 3.0 + 1. 2, respectively). However, despite trends in both the x-ray and histological data there was no statistical difference in the amount of new bone formed among the four treatment groups (P > 0.05). This was most likely due to the large variance in the data scatter and the small number of animals per group. In the second animal study, bovine-derived BMPs and the polymeric carrier were gamma irradiated separately, at doses of 1.5 or 2.5 Mrad, and their ability to form bone in a rat skull onlay model was evaluated using Sprague-Dawley rats (n = 5 per treatment group). Histomorphometry of skull caps harvested 28 days after implantation showed no significant differences as compared to non-irradiated samples, in implant area, new bone area, and percent new bone (P

  11. Measuring absorbed dose for i-CAT CBCT examinations in child, adolescent and adult phantoms

    PubMed Central

    Choi, E

    2015-01-01

    Objectives: Design and construct child and adolescent head phantoms to measure the absorbed doses imparted during dental CBCT and compare with the absorbed dose measured in an adult phantom. Methods: A child phantom was developed to represent the smallest patients receiving CBCT, usually for craniofacial developmental concerns, and an adolescent phantom was developed to represent healthy orthodontic patients. Absorbed doses were measured using a thimble ionization chamber for the custom-built child and adolescent phantoms and compared with measurements using a commercially available adult phantom. Imaging was performed with an i-CAT Next Generation (Imaging Sciences International, Hatfield, PA) CBCT using two different fields of view covering the craniofacial complex (130 mm high) or maxilla/mandible (60 mm high). Results: Measured absorbed doses varied depending on the location of the ionization chamber within the phantoms. For CBCT images obtained using the same protocol for all phantoms, the highest absorbed dose was measured in all locations of the small child phantom. The lowest absorbed dose was measured in the adult phantom. Conclusions: Images were obtained with the same protocol for the adult, adolescent and child phantoms. A consistent trend was observed with the highest absorbed dose being measured in the smallest phantom (child), while the lowest absorbed dose was measured in the largest phantom (adult). This study demonstrates the importance of child-sizing the dose by using dedicated paediatric protocols optimized for the imaging task, which is critical as children are more sensitive to harmful effects of radiation and have a longer life-span post-irradiation for radiation-induced symptoms to develop than do adults. PMID:25785822

  12. Genetic effects induced by neutrons in Drosophila melanogaster I. Determination of absorbed dose.

    PubMed

    Delfin, A; Paredes, L C; Zambrano, F; Guzmán-Rincón, J; Ureña-Nuñez, F

    2001-12-01

    A method to obtain the absorbed dose in Drosophila melanogaster irradiated in the thermal column facility of the Triga Mark III Reactor has been developed. The method is based on the measurements of neutron activation of gold foils produced by neutron capture to obtain the neutron fluxes. These fluxes, combined with the calculations of kinetic energy released per unit mass, enables one to obtain the absorbed doses in Drosophila melanogaster. PMID:11761104

  13. SU-E-T-371: Validation of Organ Doses Delivered During Craniospinal Irradiation with Helical Tomotherapy

    SciTech Connect

    Perez-Andujar, A; Chen, J; Garcia, A; Haas-Kogan, D

    2014-06-01

    Purpose: New techniques have been developed to deliver more conformal treatments to the craniospinal axis. One concern, however, is the widespread low dose delivered and implications for possible late effects. The purpose of this work is for the first time to validate the organ doses calculated by the treatment planning system (TPS), including out-of-field doses for a pediatric craniospinal treatment (CSI). Methods: A CSI plan prescribed to 23.4 Gy and a posterior fossa boost plan to 30.6 Gy (total dose 54.0 Gy) was developed for a pediatric anthropomorphic phantom representing a 13 yearold- child. For the CSI plan, the planning target volumes (PTV) consisted of the brain and spinal cord with 2 mm and 5 mm expansions, respectively. Organs at risk (OAR) were contoured and included in the plan optimization. The plans were delivered on a helical tomotherapy unit. Thermoluminescent dosimeters (TLDs) were used to measure the dose at 54 positions within the PTV and OARs. Results: For the CSI treatment, the mean percent difference between TPS dose calculations and measurements was 5% for the PTV and 10% for the OARs. For the boost, the average was 3% for the PTV. The percent difference for the OARs, which lie outside the field and received a small fraction of the prescription dose, varied from 15% to 200%. However in terms of absolute dose, the average difference between measurement and TPS per treatment Gy was 2 cGy/Gy and 3 mGy/Gy for the CSI and boost plans, respectively. Conclusion: There was good agreement between doses calculated by the TPS and measurements for the CSI treatment. Higher percent differences were observed for out-of-field doses in the boost plan, but absolute dose differences were very small compared to the prescription dose. These findings can help in the estimation of late effects after radiotherapy for pediatric patients.

  14. Space Radiation Absorbed Dose Distribution in a Human Phantom Torso

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Yang, T.; Atwell, W.

    2000-01-01

    The flight of a human phantom torso with head that containing active dosimeters at 5 organ sites and 1400 TLDs distributed in 34 1" thick sections is described. Experimental dose rates and quality factors are compared with calculations for shielding distributions at the sites using the Computerized Anatomical Male (CAM) model. The measurements were complemented with those obtained from other instruments. These results have provided the most comprehensive data set to map the dose distribution inside a human and to assess the accuracy of radiation transport models and astronaut radiation risk.

  15. Estimating the actual dose delivered by intravascular coronary brachytherapy using geometrically correct 3D modeling

    NASA Astrophysics Data System (ADS)

    Wahle, Andreas; Lopez, John J.; Pennington, Edward C.; Meeks, Sanford L.; Braddy, Kathleen C.; Fox, James M.; Brennan, Theresa M. H.; Buatti, John M.; Rossen, James D.; Sonka, Milan

    2003-05-01

    Intravascular brachytherapy has shown to reduce re-occurrence of in-stent restenosis in coronary arteries. For beta radiation, application time is determined from source activity and the angiographically estimated vessel diameter. Conventionally used dosing models assume a straight vessel with the catheter centered and a constant-diameter circular cross section. Aim of this study was to compare the actual dose delivered during in-vivo intravascular brachytherapy with the target range determined from the patient's prescribed dose. Furthermore, differences in dose distribution between a simplified tubular model (STM) and a geometrically correct 3-D model (GCM) obtained from fusion between biplane angiography and intravascular ultrasound were quantified. The tissue enclosed by the segmented lumen/plaque and media/adventitia borders was simulated using a structured finite-element mesh. The beta-radiation sources were modeled as 3-D objects in their angiographically determined locations. The accumulated dose was estimated using a fixed distance function based on the patient-specific radiation parameters. For visualization, the data was converted to VRML with the accumulated doses represented by color encoding. The statistical comparison between STM and GCM models in 8 patients showed that the STM significantly underestimates the dose delivered and its variability. The analysis revealed substantial deviations from the target dose range in curved vessels.

  16. Morphological transformation of Syrian hamster embryo cells by low doses of fission neutrons delivered at different dose rates

    SciTech Connect

    Jones, C.A.; Sedita, B.A. ); Hill, C.K. . Cancer Research Lab.); Elkind, M.M. . Dept. of Radiology and Radiation Biology)

    1991-01-01

    Both induction of cell transformation and killing were examined with Syrian hamster embryo (SHE) fibroblasts exposed to low doses of JANUS fission-spectrum neutrons delivered at high (10.3 cGy/min) and low (0.43 and 0.086 cGy/min) dose rates. Second-passage cells were irradiated in mass cultures, then cloned over feeder cells. Morphologically transformed colonies were identified 8-10 days later. Cell killing was independent of dose rate, but the yield of transformation was greater after low-dose-rate irradiations. Decreasing the neutron dose-rate from 10.3 to 0.086 cGy/min resulted in a two- to threefold increase in the yield of transformation for neutron exposures below 50 cGy, and enhancement which was consistently observed in repetitive experiments in different radiosensitive SHE cell preparations. 43 refs., 5 figs., 1 tab.

  17. Absorbed dose simulations in near-surface regions using high dose rate Iridium-192 sources applied for brachytherapy

    NASA Astrophysics Data System (ADS)

    Moura, E. S.; Zeituni, C. A.; Sakuraba, R. K.; Gonçalves, V. D.; Cruz, J. C.; Júnior, D. K.; Souza, C. D.; Rostelato, M. E. C. M.

    2014-02-01

    Brachytherapy treatment with Iridium-192 high dose rate (HDR) sources is widely used for various tumours and it could be developed in many anatomic regions. Iridium-192 sources are inserted inside or close to the region that will be treated. Usually, the treatment is performed in prostate, gynaecological, lung, breast and oral cavity regions for a better clinical dose coverage compared with other techniques, such as, high energy photons and Cobalt-60 machines. This work will evaluate absorbed dose distributions in near-surface regions around Ir-192 HDR sources. Near-surface dose measurements are a complex task, due to the contribution of beta particles in the near-surface regions. These dose distributions should be useful for non-tumour treatments, such as keloids, and other non-intracavitary technique. For the absorbed dose distribution simulations the Monte Carlo code PENELOPE with the general code penEasy was used. Ir-192 source geometry and a Polymethylmethacrylate (PMMA) tube, for beta particles shield were modelled to yield the percentage depth dose (PDD) on a cubic water phantom. Absorbed dose simulations were realized at the central axis to yield the Ir-192 dose fall-off along central axis. The results showed that more than 99.2% of the absorbed doses (relative to the surface) are deposited in 5 cm depth but with slower rate at higher distances. Near-surface treatments with Ir-192 HDR sources yields achievable measurements and with proper clinical technique and accessories should apply as an alternative for treatment of lesions where only beta sources were used.

  18. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G. ); Poston, J.W. . Dept. of Nuclear Engineering)

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No diffusion of the radionuclide into the blood vessel was assumed nor cross fire between vessel was assumed. Results are useful in assessing the dose in blood and blood vessel walls for different nuclear medicine procedures. 6 refs., 6 figs., 5 tabs.

  19. Absorbed dose calculations to blood and blood vessels for internally deposited radionuclides

    SciTech Connect

    Akabani, G.; Poston, J.W. Sr. )

    1991-05-01

    At present, absorbed dose calculations for radionuclides in the human circulatory system used relatively simple models and are restricted in their applications. To determine absorbed doses to the blood and to the surface of the blood vessel wall, EGS4 Monte Carlo calculations were performed. Absorbed doses were calculated for the blood and the blood vessel wall (lumen) for different blood vessels sizes. The radionuclides chosen for this study were those commonly used in nuclear medicine. No penetration of the radionuclide into the blood vessel was assumed nor was cross fire between the vessel assumed. The results are useful in assessing the dose to blood and blood vessel walls for different nuclear medicine procedures.

  20. New absorbed dose measurement with cylindrical water phantoms for multidetector CT

    NASA Astrophysics Data System (ADS)

    Ohno, Takeshi; Araki, Fujio; Onizuka, Ryota; Hioki, Kazunari; Tomiyama, Yuuki; Yamashita, Yusuke

    2015-06-01

    The aim of this study was to develop new dosimetry with cylindrical water phantoms for multidetector computed tomography (MDCT). The ionization measurement was performed with a Farmer ionization chamber at the center and four peripheral points in the body-type and head-type cylindrical water phantoms. The ionization was converted to the absorbed dose using a 60Co absorbed-dose-to-water calibration factor and Monte Carlo (MC) -calculated correction factors. The correction factors were calculated from MDCT (Brilliance iCT, 64-slice, Philips Electronics) modeled with GMctdospp (IMPS, Germany) software based on the EGSnrc MC code. The spectrum of incident x-ray beams and the configuration of a bowtie filter for MDCT were determined so that calculated photon intensity attenuation curves for aluminum (Al) and calculated off-center ratio (OCR) profiles in air coincided with those measured. The MC-calculated doses were calibrated by the absorbed dose measured at the center in both cylindrical water phantoms. Calculated doses were compared with measured doses at four peripheral points and the center in the phantom for various beam pitches and beam collimations. The calibration factors and the uncertainty of the absorbed dose determined using this method were also compared with those obtained by CTDIair (CT dose index in air). Calculated Al half-value layers and OCRs in air were within 0.3% and 3% agreement with the measured values, respectively. Calculated doses at four peripheral points and the centers for various beam pitches and beam collimations were within 5% and 2% agreement with measured values, respectively. The MC-calibration factors by our method were 44-50% lower than values by CTDIair due to the overbeaming effect. However, the calibration factors for CTDIair agreed within 5% with those of our method after correction for the overbeaming effect. Our method makes it possible to directly measure the absorbed dose for MDCT and is more robust and accurate than the

  1. New absorbed dose measurement with cylindrical water phantoms for multidetector CT.

    PubMed

    Ohno, Takeshi; Araki, Fujio; Onizuka, Ryota; Hioki, Kazunari; Tomiyama, Yuuki; Yamashita, Yusuke

    2015-06-01

    The aim of this study was to develop new dosimetry with cylindrical water phantoms for multidetector computed tomography (MDCT). The ionization measurement was performed with a Farmer ionization chamber at the center and four peripheral points in the body-type and head-type cylindrical water phantoms. The ionization was converted to the absorbed dose using a (60)Co absorbed-dose-to-water calibration factor and Monte Carlo (MC) -calculated correction factors. The correction factors were calculated from MDCT (Brilliance iCT, 64-slice, Philips Electronics) modeled with GMctdospp (IMPS, Germany) software based on the EGSnrc MC code. The spectrum of incident x-ray beams and the configuration of a bowtie filter for MDCT were determined so that calculated photon intensity attenuation curves for aluminum (Al) and calculated off-center ratio (OCR) profiles in air coincided with those measured. The MC-calculated doses were calibrated by the absorbed dose measured at the center in both cylindrical water phantoms. Calculated doses were compared with measured doses at four peripheral points and the center in the phantom for various beam pitches and beam collimations. The calibration factors and the uncertainty of the absorbed dose determined using this method were also compared with those obtained by CTDIair (CT dose index in air). Calculated Al half-value layers and OCRs in air were within 0.3% and 3% agreement with the measured values, respectively. Calculated doses at four peripheral points and the centers for various beam pitches and beam collimations were within 5% and 2% agreement with measured values, respectively. The MC-calibration factors by our method were 44-50% lower than values by CTDIair due to the overbeaming effect. However, the calibration factors for CTDIair agreed within 5% with those of our method after correction for the overbeaming effect. Our method makes it possible to directly measure the absorbed dose for MDCT and is more robust and accurate than the

  2. 3D delivered dose assessment using a 4DCT-based motion model

    SciTech Connect

    Cai, Weixing; Hurwitz, Martina H.; Williams, Christopher L.; Dhou, Salam; Berbeco, Ross I.; Mishra, Pankaj E-mail: jhlewis@lroc.harvard.edu; Lewis, John H. E-mail: jhlewis@lroc.harvard.edu; Seco, Joao

    2015-06-15

    Purpose: The purpose of this work is to develop a clinically feasible method of calculating actual delivered dose distributions for patients who have significant respiratory motion during the course of stereotactic body radiation therapy (SBRT). Methods: A novel approach was proposed to calculate the actual delivered dose distribution for SBRT lung treatment. This approach can be specified in three steps. (1) At the treatment planning stage, a patient-specific motion model is created from planning 4DCT data. This model assumes that the displacement vector field (DVF) of any respiratory motion deformation can be described as a linear combination of some basis DVFs. (2) During the treatment procedure, 2D time-varying projection images (either kV or MV projections) are acquired, from which time-varying “fluoroscopic” 3D images of the patient are reconstructed using the motion model. The DVF of each timepoint in the time-varying reconstruction is an optimized linear combination of basis DVFs such that the 2D projection of the 3D volume at this timepoint matches the projection image. (3) 3D dose distribution is computed for each timepoint in the set of 3D reconstructed fluoroscopic images, from which the total effective 3D delivered dose is calculated by accumulating deformed dose distributions. This approach was first validated using two modified digital extended cardio-torso (XCAT) phantoms with lung tumors and different respiratory motions. The estimated doses were compared to the dose that would be calculated for routine 4DCT-based planning and to the actual delivered dose that was calculated using “ground truth” XCAT phantoms at all timepoints. The approach was also tested using one set of patient data, which demonstrated the application of our method in a clinical scenario. Results: For the first XCAT phantom that has a mostly regular breathing pattern, the errors in 95% volume dose (D95) are 0.11% and 0.83%, respectively for 3D fluoroscopic images

  3. 3D delivered dose assessment using a 4DCT-based motion model

    PubMed Central

    Cai, Weixing; Hurwitz, Martina H.; Williams, Christopher L.; Dhou, Salam; Berbeco, Ross I.; Seco, Joao; Mishra, Pankaj; Lewis, John H.

    2015-01-01

    Purpose: The purpose of this work is to develop a clinically feasible method of calculating actual delivered dose distributions for patients who have significant respiratory motion during the course of stereotactic body radiation therapy (SBRT). Methods: A novel approach was proposed to calculate the actual delivered dose distribution for SBRT lung treatment. This approach can be specified in three steps. (1) At the treatment planning stage, a patient-specific motion model is created from planning 4DCT data. This model assumes that the displacement vector field (DVF) of any respiratory motion deformation can be described as a linear combination of some basis DVFs. (2) During the treatment procedure, 2D time-varying projection images (either kV or MV projections) are acquired, from which time-varying “fluoroscopic” 3D images of the patient are reconstructed using the motion model. The DVF of each timepoint in the time-varying reconstruction is an optimized linear combination of basis DVFs such that the 2D projection of the 3D volume at this timepoint matches the projection image. (3) 3D dose distribution is computed for each timepoint in the set of 3D reconstructed fluoroscopic images, from which the total effective 3D delivered dose is calculated by accumulating deformed dose distributions. This approach was first validated using two modified digital extended cardio-torso (XCAT) phantoms with lung tumors and different respiratory motions. The estimated doses were compared to the dose that would be calculated for routine 4DCT-based planning and to the actual delivered dose that was calculated using “ground truth” XCAT phantoms at all timepoints. The approach was also tested using one set of patient data, which demonstrated the application of our method in a clinical scenario. Results: For the first XCAT phantom that has a mostly regular breathing pattern, the errors in 95% volume dose (D95) are 0.11% and 0.83%, respectively for 3D fluoroscopic images

  4. Contrast-enhanced radiotherapy: feasibility and characteristics of the physical absorbed dose distribution for deep-seated tumors

    NASA Astrophysics Data System (ADS)

    Garnica-Garza, H. M.

    2009-09-01

    Radiotherapy using kilovoltage x-rays in conjunction with contrast agents incorporated into the tumor, gold nanoparticles in particular, could represent a potential alternative to current techniques based on high-energy linear accelerators. In this paper, using the voxelized Zubal phantom in conjunction with the Monte Carlo code PENELOPE to model a prostate cancer treatment, it is shown that in combination with a 360° arc delivery technique, tumoricidal doses of radiation can be delivered to deep-seated tumors while still providing acceptable doses to the skin and other organs at risk for gold concentrations in the tumor within the range of 7-10 mg-Au per gram of tissue. Under these conditions and using a x-ray beam with 90% of the fluence within the range of 80-200 keV, a 72 Gy physical absorbed dose to the prostate can be delivered, while keeping the rectal wall, bladder, skin and femoral heads below 65 Gy, 55 Gy, 40 Gy and 30 Gy, respectively. However, it is also shown that non-uniformities in the contrast agent concentration lead to a severe degradation of the dose distribution and that, therefore, techniques to locally quantify the presence of the contrast agent would be necessary in order to determine the incident x-ray fluence that best reproduces the dosimetry obtained under conditions of uniform contrast agent distribution.

  5. Contrast-enhanced radiotherapy: feasibility and characteristics of the physical absorbed dose distribution for deep-seated tumors.

    PubMed

    Garnica-Garza, H M

    2009-09-21

    Radiotherapy using kilovoltage x-rays in conjunction with contrast agents incorporated into the tumor, gold nanoparticles in particular, could represent a potential alternative to current techniques based on high-energy linear accelerators. In this paper, using the voxelized Zubal phantom in conjunction with the Monte Carlo code PENELOPE to model a prostate cancer treatment, it is shown that in combination with a 360 degrees arc delivery technique, tumoricidal doses of radiation can be delivered to deep-seated tumors while still providing acceptable doses to the skin and other organs at risk for gold concentrations in the tumor within the range of 7-10 mg-Au per gram of tissue. Under these conditions and using a x-ray beam with 90% of the fluence within the range of 80-200 keV, a 72 Gy physical absorbed dose to the prostate can be delivered, while keeping the rectal wall, bladder, skin and femoral heads below 65 Gy, 55 Gy, 40 Gy and 30 Gy, respectively. However, it is also shown that non-uniformities in the contrast agent concentration lead to a severe degradation of the dose distribution and that, therefore, techniques to locally quantify the presence of the contrast agent would be necessary in order to determine the incident x-ray fluence that best reproduces the dosimetry obtained under conditions of uniform contrast agent distribution.

  6. Estimating absorbed dose of pesticides in a field setting using biomonitoring data and pharmacokinetic models.

    PubMed

    Scher, Deanna P; Sawchuk, Ronald J; Alexander, Bruce H; Adgate, John L

    2008-01-01

    Linking biomarker data to pharmacokinetic (PK) models permits comparison of absorbed dose with a toxicological benchmark, which is an important step to understanding the health implications of pesticide exposure. The purpose of this analysis was to evaluate the feasibility of reconstructing the absorbed dose of two pesticides using PK models developed from biomarker data in a study of occupational application of these compounds. Twenty-four-hour urine samples were collected from farmers 24 h before through 96 h after a typical application of chlorpyrifos or 2,4-D. PK models were used to link the amounts found in urine samples to absorbed dose. Modeled total body dose estimates (in micrograms) were compared to measured dose from time 0-96 h. Despite the complexities surrounding the interpretation of biomonitoring data from a field setting, the models developed as part of this analysis accurately estimated the absorbed dose of 2,4-D and chlorpyrifos when collection of urine samples was largely complete. Over half of the farmers were excluded from modeling due to suspected noncompliance with urine collection or confounding exposure events, which highlights the importance of these issues for designing and interpreting biomonitoring data in future studies. Further evaluation of PK models in scenarios using single void samples is warranted for improving field-based dose assessments.

  7. Acne Treatment Based on Selective Photothermolysis of Sebaceous Follicles with Topically Delivered Light-Absorbing Gold Microparticles

    PubMed Central

    Paithankar, Dilip Y; Sakamoto, Fernanda H; Farinelli, William A; Kositratna, Garuna; Blomgren, Richard D; Meyer, Todd J; Faupel, Linda J; Kauvar, Arielle N B; Lloyd, Jenifer R; Cheung, Wang L; Owczarek, Witold D; Suwalska, Anna M; Kochanska, Katarzyna B; Nawrocka, Agnieszka K; Paluchowska, Elwira B; Podolec, Katarzyna M; Pirowska, Magdalena M; Wojas-Pelc, Anna B; Anderson, R Rox

    2015-01-01

    The pathophysiology of acne vulgaris depends on active sebaceous glands, implying that selective destruction of sebaceous glands could be an effective treatment. We hypothesized that light-absorbing microparticles could be delivered into sebaceous glands, enabling local injury by optical pulses. A suspension of topically applied gold-coated silica microparticles exhibiting plasmon resonance with strong absorption at 800 nm was delivered into human pre-auricular and swine sebaceous glands in vivo, using mechanical vibration. After exposure to 10–50 J cm−2, 30 milliseconds, 800 nm diode laser pulses, microscopy revealed preferential thermal injury to sebaceous follicles and glands, consistent with predictions from a computational model. Inflammation was mild; gold particles were not retained in swine skin 1 month after treatment, and uptake in other organs was negligible. Two independent prospective randomized controlled clinical trials were performed for treatment of moderate-to-severe facial acne, using unblinded and blinded assessments of disease severity. Each trial showed clinically and statistically significant improvement of inflammatory acne following three treatments given 1–2 weeks apart. In Trial 2, inflammatory lesions were significantly reduced at 12 weeks (P=0.015) and 16 weeks (P=0.04) compared with sham treatments. Optical microparticles enable selective photothermolysis of sebaceous glands. This appears to be a well-tolerated, effective treatment for acne vulgaris. PMID:25748556

  8. Nominal effective radiation doses delivered during clinical trials of boron neutron capture therapy

    SciTech Connect

    Capala, J.; Diaz, A.Z.; Chanana, A.D.

    1997-12-31

    Boron neutron capture therapy (BNCT) is a binary system that, in theory, should selectively deliver lethal, high linear energy transfer (LET) radiation to tumor cells dispersed within normal tissues. It is based on the nuclear reaction 10-B(n, {alpha})7-Li, which occurs when the stable nucleus of boron-10 captures a thermal neutron. Due to the relatively high cross-section of the 10-B nucleus for thermal neutron capture and short ranges of the products of this reaction, tumor cells in the volume exposed to thermal neutrons and containing sufficiently high concentration of 10-B would receive a much higher radiation dose than the normal cells contained within the exposed volume. Nevertheless, radiation dose deposited in normal tissue by gamma and fast neutron contamination of the neutron beam, as well as neutron capture in nitrogen, 14-N(n,p)14-C, hydrogen, 1-H(n,{gamma})2-H, and in boron present in blood and normal cells, limits the dose that can be delivered to tumor cells. It is, therefore, imperative for the success of the BNCT the dosed delivered to normal tissues be accurately determined in order to optimize the irradiation geometry and to limit the volume of normal tissue exposed to thermal neutrons. These are the major objectives of BNCT treatment planning.

  9. Absorbed Dose in the Uterus of a Three Months Pregnant Woman Due to 131I

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, Héctor René; Manzanares-Acuña, Eduardo; Hernández-Dávila, Víctor Martín; Arcos-Pichardo, Areli; Barquero, Raquel; Iñiguez, M. Pilar

    2006-09-01

    The use of 131I is widely used in diagnostic and treatment of patients. If the patient is pregnant the 131I presence in the thyroid it becomes a source of constant exposition to other organs and the fetus. In this study the absorbed dose in the uterus of a 3 months pregnant woman with 131I in her thyroid gland has been calculated. The dose was determined using Monte Carlo methods in which a detailed model of the woman has been developed. The dose was also calculated using a simple procedure that was refined including the photons' attenuation in the woman organs and body. To verify these results an experiment was carried out using a neck phantom with 131I. Comparing the results it was found that the simple calculation tend to overestimate the absorbed dose, by doing the corrections due to body and organs photon attenuation the dose is 0.14 times the Monte Carlo estimation.

  10. Absorbed XFEL Dose in the Components of the LCLS X-Ray Optics

    SciTech Connect

    Hau-Riege, Stefan

    2010-12-03

    There is great concern that the short, intense XFEL pulse of the LCLS will damage the optics that will be placed into the beam. We have analyzed the extent of the problem by considering the anticipated materials and position of the optical components in the beam path, calculated the absorbed dose as a function of photon energy, and compared these doses with the expected doses required (i) to observe rapid degradation due to thermal fatigue, (ii) to reach the melting temperature, or (iii) to actually melt the material. We list the materials that are anticipated to be placed into the Linac Coherent Light Source (LCLS) x-ray free electron laser (XFEL) beam line, their positions, and the absorbed dose, and compare this dose with anticipated damage thresholds.

  11. Absorbed Dose in the Uterus of a Three Months Pregnant Woman Due to 131I

    SciTech Connect

    Vega-Carrillo, Hector Rene; Manzanares-Acuna, Eduardo; Hernandez-Davila, Victor Martin; Arcos-Pichardo, Areli; Barquero, Raquel; Iniguez, M. Pilar

    2006-09-08

    The use of 131I is widely used in diagnostic and treatment of patients. If the patient is pregnant the 131I presence in the thyroid it becomes a source of constant exposition to other organs and the fetus. In this study the absorbed dose in the uterus of a 3 months pregnant woman with 131I in her thyroid gland has been calculated. The dose was determined using Monte Carlo methods in which a detailed model of the woman has been developed. The dose was also calculated using a simple procedure that was refined including the photons' attenuation in the woman organs and body. To verify these results an experiment was carried out using a neck phantom with 131I. Comparing the results it was found that the simple calculation tend to overestimate the absorbed dose, by doing the corrections due to body and organs photon attenuation the dose is 0.14 times the Monte Carlo estimation.

  12. Air kerma and absorbed dose standards for reference dosimetry in brachytherapy

    PubMed Central

    2014-01-01

    This article reviews recent developments in primary standards for the calibration of brachytherapy sources, with an emphasis on the currently most common photon-emitting radionuclides. The introduction discusses the need for reference dosimetry in brachytherapy in general. The following section focuses on the three main quantities, i.e. reference air kerma rate, air kerma strength and absorbed dose rate to water, which are currently used for the specification of brachytherapy photon sources and which can be realized with primary standards from first principles. An overview of different air kerma and absorbed dose standards, which have been independently developed by various national metrology institutes over the past two decades, is given in the next two sections. Other dosimetry techniques for brachytherapy will also be discussed. The review closes with an outlook on a possible transition from air kerma to absorbed dose to water-based calibrations for brachytherapy sources in the future. PMID:24814696

  13. Average fetal depth in utero: data for estimation of fetal absorbed radiation dose

    SciTech Connect

    Ragozzino, M.W.; Breckle, R.; Hill, L.M.; Gray, J.E.

    1986-02-01

    To estimate fetal absorbed dose from radiographic examinations, the depth from the anterior maternal surface to the midline of the fetal skull and abdomen was measured by ultrasound in 97 pregnant women. The relationships between fetal depth, fetal presentation, and maternal parameters of height, weight, anteroposterior (AP) thickness, gestational age, placental location, and bladder volume were analyzed. Maternal AP thickness (MAP) can be estimated from gestational age, maternal height, and maternal weight. Fetal midskull and abdominal depths were nearly equal. Fetal depth normalized to MAP was independent or nearly independent of maternal parameters and fetal presentation. These data enable a reasonable estimation of absorbed dose to fetal brain, abdomen, and whole body.

  14. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator

    NASA Astrophysics Data System (ADS)

    Puchalska, Monika; Sihver, Lembit

    2015-06-01

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18 MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature.

  15. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator.

    PubMed

    Puchalska, Monika; Sihver, Lembit

    2015-06-21

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18 MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature.

  16. Plasma Membrane Permeabilization by 60- and 600-ns Electric Pulses Is Determined by the Absorbed Dose

    PubMed Central

    Ibey, Bennett L.; Xiao, Shu; Schoenbach, Karl H.; Murphy, Michael R.; Pakhomov, Andrei G.

    2008-01-01

    We explored how the effect of plasma membrane permeabilization by nanosecond-duration electric pulses (nsEP) depends on the physical characteristics of exposure. The resting membrane resistance (Rm) and membrane potential (MP) were measured in cultured GH3 and CHO cells by conventional whole-cell patch-clamp technique. Intact cells were exposed to a single nsEP (60 or 600 ns duration, 0-22 kV/cm), followed by patch-clamp measurements after a 2-3 min delay. Consistent with earlier findings, nsEP caused long-lasting Rm decrease, accompanied by the loss of MP. The threshold for these effects was about 6 kV/cm for 60 ns pulses, and about 1 kV/cm for 600 ns pulses. Further analysis established that it was neither pulse duration nor the E-field amplitude per se, but the absorbed dose that determined the magnitude of the biological effect. In other words, exposure to nsEP at either pulse duration caused equal effects if the absorbed doses were equal. The threshold absorbed dose to produce plasma membrane effects in either GH3 or CHO cells at either pulse duration was found to be at or below 10 mJ/g. Despite being determined by the dose, the nsEP effect clearly is not thermal, as the maximum heating at the threshold dose is less than 0.01 °C. The use of the absorbed dose as a universal exposure metric may help to compare and quantify nsEP sensitivity of different cell types and of cells in different physiological conditions. The absorbed dose may also prove to be a more useful metric than the incident E-field in determining safety limits for high peak, lowaverage power EMF emissions. PMID:18839412

  17. Absorbed doses of lungs from radon retained in airway lumens of mice and rats.

    PubMed

    Sakoda, Akihiro; Ishimori, Yuu; Yamaoka, Kiyonori; Kataoka, Takahiro; Mitsunobu, Fumihiro

    2013-08-01

    This paper provides absorbed doses arising from radon gas in air retained in lung airway lumens. Because radon gas exposure experiments often use small animals, the calculation was performed for mice and rats. For reference, the corresponding computations were also done for humans. Assuming that radon concentration in airway lumens is the same as that in the environment, its progeny's production in and clearance from airways were simulated. Absorbed dose rates were obtained for three lung regions and the whole lung, considering that secretory and basal cells are sensitive to radiation. The results showed that absorbed dose rates for all lung regions and whole lung generally increase from mice to rats to humans. For example, the dose rates for the whole lung were 25.4 in mice, 41.7 in rats, and 59.9 pGy (Bq m⁻³)⁻¹ h⁻¹ in humans. Furthermore, these values were also compared with lung dose rates from two other types of exposures, that is, due to inhalation of radon or its progeny, which were already reported. It was confirmed that the direct inhalation of radon progeny in the natural environment, which is known as a cause of lung cancer, results in the highest dose rates for all species. Based on the present calculations, absorbed dose rates of the whole lung from radon gas were lower by a factor of about 550 (mice), 200 (rats), or 70 (humans) than those from radon progeny inhalation. The calculated dose rate values are comparatively small. Nevertheless, the present study is considered to contribute to our understanding of doses from inhalation of radon and its progeny.

  18. Uncertainties of organ-absorbed doses to patients from 18f-choline

    NASA Astrophysics Data System (ADS)

    Li, W. B.; Janzen, T.; Zankl, M.; Giussani, A.; Hoeschen, C.

    2011-03-01

    Radiation doses of radiopharmaceuticals to patients in nuclear medicine are, as the standard method, estimated by the administered activity, medical imaging (e.g. PET imaging), compartmental modeling and Monte Carlo simulation of radiation with reference digital human phantoms. However, in each of the contributing terms, individual uncertainty due to measurement techniques, patient variability and computation methods may propagate to the uncertainties of the calculated organ doses to the individual patient. To evaluate the overall uncertainties and the quality assurance of internal absorbed doses, a method was developed within the framework of the MADEIRA Project (Minimizing Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations) to quantitatively analyze the uncertainties in each component of the organ absorbed doses after administration of 18F-choline to prostate cancer patients undergoing nuclear medicine diagnostics. First, on the basis of the organ PET and CT images of the patients as well as blood and urine samples, a model structure of 18F-choline was developed and the uncertainties of the model parameters were determined. Second, the model parameter values were sampled and biokinetic modeling using these sampled parameter values were performed. Third, the uncertainties of the new specific absorbed fraction (SAF) values derived with different phantoms representing individual patients were presented. Finally, the uncertainties of absorbed doses to the patients were calculated by applying the ICRP/ICRU adult male reference computational phantom. In addition to the uncertainty analysis, the sensitivity of the model parameters on the organ PET images and absorbed doses was indicated by coupling the model input and output using regression and partial correlation analysis. The results showed that the uncertainty factors of absorbed dose to patients are in most cases less than a factor of 2 without taking into account the uncertainties

  19. Improved estimates of the radiation absorbed dose to the urinary bladder wall

    NASA Astrophysics Data System (ADS)

    Andersson, Martin; Minarik, David; Johansson, Lennart; Mattsson, Sören; Leide-Svegborn, Sigrid

    2014-05-01

    Specific absorbed fractions (SAFs) have been calculated as a function of the content in the urinary bladder in order to allow more realistic calculations of the absorbed dose to the bladder wall. The SAFs were calculated using the urinary bladder anatomy from the ICRP male and female adult reference computational phantoms. The urinary bladder and its content were approximated by a sphere with a wall of constant mass, where the thickness of the wall depended on the amount of urine in the bladder. SAFs were calculated for males and females with 17 different urinary bladder volumes from 10 to 800 mL, using the Monte Carlo computer program MCNP5, at 25 energies of mono-energetic photons and electrons ranging from 10 KeV to 10 MeV. The decay was assumed to be homogeneously distributed in the urinary bladder content and the urinary bladder wall, and the mean absorbed dose to the urinary bladder wall was calculated. The Monte Carlo simulations were validated against measurements made with thermoluminescent dosimeters. The SAFs obtained for a urine volume of 200 mL were compared to the values calculated for the urinary bladder wall using the adult reference computational phantoms. The mean absorbed dose to the urinary wall from 18F-FDG was found to be 77 µGy/MBq formales and 86 µGy/MBq for females, while for 99mTc-DTPA the mean absorbed doses were 80 µGy/MBq for males and 86 µGy/MBq for females. Compared to calculations using a constant value of the SAF from the adult reference computational phantoms, the mean absorbed doses to the bladder wall were 60% higher for 18F-FDG and 30% higher for 99mTc-DTPA using the new SAFs.

  20. Diamond detector in absorbed dose measurements in high-energy linear accelerator photon and electron beams.

    PubMed

    Ravichandran, Ramamoorthy; Binukumar, John Pichy; Al Amri, Iqbal; Davis, Cheriyathmanjiyil Antony

    2016-01-01

    Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue-equivalent properties. We investigated a commercially available 'microdiamond' detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm3, radius 1.1mm, thickness 1 x10(-3) mm, the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ± 0.17% (1 SD) (n = 11). The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stop-ping power ratios compared well with Nd, water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long-term stability and reproducibility. Based on micro-dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance. PMID:27074452

  1. Daily variations in delivered doses in patients treated with radiotherapy for localized prostate cancer

    SciTech Connect

    Kupelian, Patrick A. . E-mail: patrick.kupelian@orhs.org; Langen, Katja M.; Zeidan, Omar A.; Meeks, Sanford L.; Willoughby, Twyla R.; Wagner, Thomas H.; Jeswani, Sam; Ruchala, Kenneth J.; Haimerl, Jason; Olivera, Gustavo H.

    2006-11-01

    Purpose: The aim of this work was to study the variations in delivered doses to the prostate, rectum, and bladder during a full course of image-guided external beam radiotherapy. Methods and Materials: Ten patients with localized prostate cancer were treated with helical tomotherapy to 78 Gy at 2 Gy per fraction in 39 fractions. Daily target localization was performed using intraprostatic fiducials and daily megavoltage pelvic computed tomography (CT) scans, resulting in a total of 390 CT scans. The prostate, rectum, and bladder were manually contoured on each CT by a single physician. Daily dosimetric analysis was performed with dose recalculation. The study endpoints were D95 (dose to 95% of the prostate), rV2 (absolute rectal volume receiving 2 Gy), and bV2 (absolute bladder volume receiving 2 Gy). Results: For the entire cohort, the average D95 ({+-}SD) was 2.02 {+-} 0.04 Gy (range, 1.79-2.20 Gy). The average rV2 ({+-}SD) was 7.0 {+-} 8.1 cc (range, 0.1-67.3 cc). The average bV2 ({+-}SD) was 8.7 {+-} 6.8 cc (range, 0.3-36.8 cc). Unlike doses for the prostate, there was significant daily variation in rectal and bladder doses, mostly because of variations in volume and shape of these organs. Conclusion: Large variations in delivered doses to the rectum and bladder can be documented with daily megavoltage CT scans. Image guidance for the targeting of the prostate, even with intraprostatic fiducials, does not take into account the variation in actual rectal and bladder doses. The clinical impact of techniques that take into account such dosimetric parameters in daily patient set-ups should be investigated.

  2. A method to efficiently simulate absorbed dose in radio-sensitive instrumentation components

    NASA Astrophysics Data System (ADS)

    Santana Leitner, M.

    2015-12-01

    Components installed in tunnels of high-power accelerators are prone to radiation-induced damage and malfunction. Such machines are usually modeled in detail and the radiation cascades are transported through the three-dimensional models in Monte Carlo codes. Very often those codes are used to compute energy deposition in beam components or radiation fields to the public and the environment. However, sensitive components such as electronic boards or insulator cables are less easily simulated, as their small size makes dose scoring a (statistically) inefficient process. Moreover the process to decide their location is iterative, as in order to define where these will be safely installed, the dose needs to be computed, but to do so the location needs to be known. This note presents a different approach to indirectly asses the potential absorbed dose by certain components when those are installed within a given radiation field. The method consists first in finding the energy and particle-dependent absorbed dose to fluence response function, and then programming those in a radiation transport Monte Carlo code, so that fluences in vacuum/air can be automatically converted real-time into potential absorbed doses and then mapped in the same way as fluences or dose equivalent magnitudes.

  3. A Graphite Absorbed-Dose Calorimeter in the Quasi-Isothermal Mode of Operation

    NASA Astrophysics Data System (ADS)

    Witzani, J.; Duftschmid, K. E.; Strachotinsky, Ch; Leitner, A.

    1984-01-01

    A quasi-isothermal method of operating an absorbed-dose graphite calorimeter is described in theory and practice. In contrast with the well-known quasi-adiabatic operation, which entails temperature increases during measurements, in the quasi-isothermal mode the temperatures of the different graphite bodies remain constant except for small temperature drifts throughout the measurement. This implies that the temperature dependence of the specific heat of the absorber and of the sensitivity of the temperature sensor influence the absorbed-dose determination significantly less. The method is characterized by a power-compensating measuring principle which is illustrated with a 3-body graphite calorimeter. Comparisons of the quasi-isothermal with the quasi-adiabatic method of operation showed good agreement.

  4. Absorbed dose rates in tissue from prompt gamma emissions from near-thermal neutron absorption

    DOE PAGES

    Schwahn, Scott O.

    2015-10-01

    Prompt gamma emission data from the International Atomic Energy Agency s Prompt Gamma-ray Neutron Activation Analysis database are analyzed to determine the absorbed dose rates in tissue to be expected when natural elements are exposed in a near-thermal neutron environment.

  5. Dose delivered from Varian's CBCT to patients receiving IMRT for prostate cancer

    NASA Astrophysics Data System (ADS)

    Wen, Ning; Guan, Huaiqun; Hammoud, Rabih; Pradhan, Deepak; Nurushev, T.; Li, Shidong; Movsas, Benjamin

    2007-04-01

    With the increased use of cone beam CT (CBCT) for daily patient setup, the accumulated dose from CBCT may be significantly higher than that from simulation CT or portal imaging. The objective of this work is to measure the dose from daily pelvic scans with fixed technical settings and collimations. CBCT scans were acquired in half-fan mode using a half bowtie and x-rays were delivered in pulsed-fluoro mode. The skin doses for seven prostate patients were measured on an IRB-approved protocol. TLD capsules were placed on the patient's skin at the central axis of three beams: AP, left lateral (Lt Lat) and right lateral (Rt Lat). To avoid the ring artefacts centred in the prostate, the treatment couch was dropped 3 cm from the patient's tattoo (central axis). The measured AP skin doses ranged 3-6 cGy for 20-33 cm separation. The larger the patient size the less the AP skin dose. Lateral doses did not change much with patient size. The Lt Lat dose was ~4.0 cGy, which was ~40% higher than the Rt Lat dose of ~2.6 cGy. To verify this dose asymmetry, surface doses on an IMRT QA phantom (oval shaped, 30 cm × 20 cm) were measured at the same three sites using TLD capsules with 3 cm table-drop. The dose asymmetry was due to: (1) kV source rotation which always starts from the patient's Lt Lat and ends at Lt Lat. Gantry rotation gets much slower near the end of rotation but dose rate stays constant and (2) 370° scan rotation (10° scan overlap on the Lt Lat side). In vivo doses were measured inside a Rando pelvic heterogeneous phantom using TLDs. The left hip (femoral head and neck) received the highest doses of ~10-11 cGy while the right hip received ~6-7 cGy. The surface and in vivo doses were also measured for phantoms at the central-axis setup. The difference was less than ~12% to the table-drop setup.

  6. Initial beam size study for passive scatter proton therapy. II. Changes in delivered depth dose profiles

    SciTech Connect

    Polf, Jerimy C.; Harvey, Mark C.; Smith, Alfred R.

    2007-11-15

    In passively scattered proton radiotherapy, a clinically useful treatment beam is produced by spreading a small proton 'pencil beam' extracted from the accelerator to create both a uniform dose profile laterally and a uniform spread-out Bragg peak (SOBP) in depth. Lateral spreading and range modulation of the beam are accomplished using specially designed components within the treatment delivery nozzle. The purpose of this study was to determine how changes in the size of the initial proton pencil beam affect the delivery of dose with a passive scatter treatment nozzle. Monte Carlo calculations were used to study changes of the beam's in-air energy distribution at the exit of the nozzle and the central axis depth dose profiles in water resulting from changes in the incident beam size. Our results indicate that the width of the delivered SOBP decreases as the size of the initial beam increases.

  7. Verification of absorbed dose using diodes in cobalt-60 radiation therapy.

    PubMed

    Gadhi, Muhammad Asghar; Fatmi, Shahab; Chughtai, Gul M; Arshad, Muhammad; Shakil, Muhammad; Rahmani, Uzma Mahmood; Imran, Malik Younas; Buzdar, Saeed Ahmad

    2016-03-01

    The objective of this work was to enhance the quality and safety of dose delivery in the practice of radiation oncology. To achieve this goal, the absorbed dose verification program was initiated by using the diode in vivo dosimetry (IVD) system (for entrance and exit). This practice was implemented at BINO, Bahawalpur, Pakistan. Diodes were calibrated for making absorbed dose measurements. Various correction factors (SSD, dose non-linearity, field size, angle of incidence, and wedge) were determined for diode IVD system. The measurements were performed in phantom in order to validate the IVD procedure. One hundred and nineteen patients were monitored and 995 measurements were performed. For phantom, the percentage difference between measured and calculated dose for entrance setting remained within ±2% and for exit setting ±3%. For patient measurements, the percentage difference between measured and calculated dose remained within ±5% for entrance/open fields and ±7% for exit/wedge/oblique fields. One hundred and nineteen patients and 995 fields have been monitored during the period of 6 months. The analysis of all available measurements gave a mean percent deviation of ±1.19% and standard deviation of ±2.87%. Larger variations have been noticed in oblique, wedge and exit measurements. This investigation revealed that clinical dosimetry using diodes is simple, provides immediate results and is a useful quality assurance tool for dose delivery. It has enhanced the quality of radiation dose delivery and increased/improved the reliability of the radiation therapy practice in BINO.

  8. Fetus absorbed dose evaluation in head and neck radiotherapy procedures of pregnant patients.

    PubMed

    da Costa, Etieli C; da Rosa, Luiz Antonio R; Batista, Delano Valdivino S

    2015-06-01

    In this work the head and neck cancer treatment of a pregnant patient was experimentally simulated. A female anthropomorphic Alderson phantom was used and the absorbed dose to the fetus was evaluated protecting the patient's abdomen with a 7cm lead layer and using no abdomen shielding. The target volume dose was 50Gy. The fetus doses evaluated with and without the lead shielding were, respectively, 0.52±0.039 and 0.88±0.052cGy. PMID:25620113

  9. Reduced radiation-absorbed dose to tissues with partial panoramic radiography for evaluation of third molars.

    PubMed

    Kircos, L T; Eakle, W S; Smith, R A

    1986-05-01

    The radiation-absorbed doses from panoramic radiography, distal molar radiography, and a partial panoramic radiographic technique that exposes only the third molar region to radiation are compared. Doses of radiation to the submandibular salivary gland were comparable by all three techniques, but doses of radiation to the head and neck were reduced greatly by the partial panoramic radiographic technique. Partial panoramic radiography is a diagnostically satisfactory and a radiologically safer technique for evaluation of third molar pathosis than is panoramic or distal molar radiography. PMID:3458783

  10. Reduced radiation-absorbed dose to tissues with partial panoramic radiography for evaluation of third molars

    SciTech Connect

    Kircos, L.T.; Eakle, W.S.; Smith, R.A.

    1986-05-01

    The radiation-absorbed doses from panoramic radiography, distal molar radiography, and a partial panoramic radiographic technique that exposes only the third molar region to radiation are compared. Doses of radiation to the submandibular salivary gland were comparable by all three techniques, but doses of radiation to the head and neck were reduced greatly by the partial panoramic radiographic technique. Partial panoramic radiography is a diagnostically satisfactory and a radiologically safer technique for evaluation of third molar pathosis than is panoramic or distal molar radiography.

  11. Electron paramagnetic resonance measurements of absorbed dose in teeth from citizens of Ozyorsk.

    PubMed

    Wieser, A; Vasilenko, E; Aladova, E; Fattibene, P; Semiochkina, N; Smetanin, M

    2014-05-01

    In 1945, within the frame of the Uranium Project for the production of nuclear weapons, the Mayak nuclear facilities were constructed at the Lake Irtyash in the Southern Urals, Russia. The nuclear workers of the Mayak Production Association (MPA), who lived in the city of Ozyorsk, are the focus of epidemiological studies for the assessment of health risks due to protracted exposure to ionising radiation. Electron paramagnetic resonance measurements of absorbed dose in tooth enamel have already been used in the past, in an effort to validate occupational external doses that were evaluated in the Mayak Worker Dosimetry System. In the present study, 229 teeth of Ozyorsk citizens not employed at MPA were investigated for the assessment of external background exposure in Ozyorsk. The annually absorbed dose in tooth enamel from natural background radiation was estimated to be (0.7 ± 0.3) mGy. For citizens living in Ozyorsk during the time of routine noble gas releases of the MPA, which peaked in 1953, the average excess absorbed dose in enamel above natural background was (36 ± 29) mGy, which is consistent with the gamma dose obtained by model calculations. In addition, there were indications of possible accidental gaseous MPA releases that affected the population of Ozyorsk, during the early and late MPA operation periods, before 1951 and after 1960. PMID:24604722

  12. Uneven surface absorbed dose distribution in electron-accelerator irradiation of rubber items

    SciTech Connect

    Gorbunov, I.F.; Pashinin, V.I.; Vanyushkin, B.M.

    1988-02-01

    Electron accelerators for industrial use are equipped with scanning devices, where the scan frequency or linear velocity along the window may vary. In a flow technology, where the items are transported to the irradiation zone at a set rate, the speed of an item may be comparable with the scan speed, so there is substantial nonuniformity in the absorbed dose, which adversely affects the quality. We have examined the dose nonuniformity for long rubber items during vulcanization by means of LUE-8-5RV and ELV-2 accelerators. The absorbed dose is calculated for an elementary part along which the irradiation is uniform on the assumption that current density distribution in the unswept beam is uniform as a result of scattering in the foil.

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    Single-arc intensity-modulated arc therapy (IMAT) has gained worldwide interest in both research and clinical implementation due to its superior plan quality and delivery efficiency. Single-arc IMAT techniques such as the Varian RapidArc™ deliver conformal dose distributions to the target in one single gantry rotation, resulting in a delivery time in the order of 2 min. The segments in these techniques are evenly distributed within an arc and are allowed to have different monitor unit (MU) weightings. Therefore, a variable dose-rate (VDR) is required for delivery. Because the VDR requirement complicates the control hardware and software of the linear accelerators (linacs) and prevents most existing linacs from delivering IMAT, we propose an alternative planning approach for IMAT using constant dose-rate (CDR) delivery with variable angular spacing. We prove the equivalence by converting VDR-optimized RapidArc plans to CDR plans, where the evenly spaced beams in the VDR plan are redistributed to uneven spacing such that the segments with larger MU weighting occupy a greater angular interval. To minimize perturbation in the optimized dose distribution, the angular deviation of the segments was restricted to <=± 5°. This restriction requires the treatment arc to be broken into multiple sectors such that the local MU fluctuation within each sector is reduced, thereby lowering the angular deviation of the segments during redistribution. The converted CDR plans were delivered with a single gantry sweep as in the VDR plans but each sector was delivered with a different value of CDR. For four patient cases, including two head-and-neck, one brain and one prostate, all CDR plans developed with the variable spacing scheme produced similar dose distributions to the original VDR plans. For plans with complex angular MU distributions, the number of sectors increased up to four in the CDR plans in order to maintain the original plan quality. Since each sector was delivered

  14. Pain and Mean Absorbed Dose to the Pubic Bone After Radiotherapy Among Gynecological Cancer Survivors

    SciTech Connect

    Waldenstroem, Ann-Charlotte; Olsson, Caroline; Wilderaeng, Ulrica; Dunberger, Gail; Lind, Helena; Al-Abany, Massoud; Palm, Asa; Avall-Lundqvist, Elisabeth; Johansson, Karl-Axel; Steineck, Gunnar

    2011-07-15

    Purpose: To analyze the relationship between mean absorbed dose to the pubic bone after pelvic radiotherapy for gynecological cancer and occurrence of pubic bone pain among long-term survivors. Methods and Materials: In an unselected, population-based study, we identified 823 long-term gynecological cancer survivors treated with pelvic radiotherapy during 1991-2003. For comparison, we used a non-radiation-treated control population of 478 matched women from the Swedish Population Register. Pain, intensity of pain, and functional impairment due to pain in the pubic bone were assessed with a study-specific postal questionnaire. Results: We analyzed data from 650 survivors (participation rate 79%) with median follow-up of 6.3 years (range, 2.3-15.0 years) along with 344 control women (participation rate, 72 %). Ten percent of the survivors were treated with radiotherapy; ninety percent with surgery plus radiotherapy. Brachytherapy was added in 81%. Complete treatment records were recovered for 538/650 survivors, with dose distribution data including dose-volume histograms over the pubic bone. Pubic bone pain was reported by 73 survivors (11%); 59/517 (11%) had been exposed to mean absorbed external beam doses <52.5 Gy to the pubic bone and 5/12 (42%) to mean absorbed external beam doses {>=}52.5 Gy. Thirty-three survivors reported pain affecting sleep, a 13-fold increased prevalence compared with control women. Forty-nine survivors reported functional impairment measured as pain walking indoors, a 10-fold increased prevalence. Conclusions: Mean absorbed external beam dose above 52.5 Gy to the pubic bone increases the occurrence of pain in the pubic bone and may affect daily life of long-term survivors treated with radiotherapy for gynecological cancer.

  15. The impact of modeling nuclear fragmentation on delivered dose and radiobiology in ion therapy.

    PubMed

    Lühr, Armin; Hansen, David C; Teiwes, Ricky; Sobolevsky, Nikolai; Jäkel, Oliver; Bassler, Niels

    2012-08-21

    The importance of nuclear interactions for ion therapy arises from the influence of the particle spectrum on, first, radiobiology and therefore also on treatment planning, second, the accuracy of measuring dose and, third, the delivered dose distribution. This study tries to determine the qualitative as well as the quantitative influence of the modeling of inelastic nuclear interactions on ion therapy. Thereby, three key disciplines are investigated, namely dose delivery, dose assessment and radiobiology. In order to perform a quantitative analysis, a relative comparison between six different descriptions of nuclear interactions is carried out for carbon ions. The particle transport is simulated with the Monte Carlo code SHIELD-HIT10A while dose planning and radiobiology are covered by the analytic treatment planning program for particles TRiP, which determines the relative biological effectiveness (RBE) with the local effect model. The obtained results show that the physical dose distribution can in principle be significantly influenced by the modeling of fragmentation (about 10% for a 20% change in all inelastic nuclear cross sections for a target volume ranging from 15 to 25 cm). While the impact of nuclear fragmentation on stopping power ratios can be neglected, the fluence correction factor may be influenced by the applied nuclear models. In contrast to the results for the physical dose, the variation of the RBE is only small (about 1% for a 20% change in all inelastic nuclear cross sections) suggesting a relatively weak dependence of radiobiology on the detailed composition of the particle energy spectrum of the mixed radiation field. Also, no significant change (about 0.2 mm) of the lateral penumbra of the RBE-weighted dose is observed.

  16. Graves' disease radioiodine-therapy: Choosing target absorbed doses for therapy planning

    SciTech Connect

    Willegaignon, J. Sapienza, M. T.; Coura-Filho, G. B.; Buchpiguel, C. A.; Watanabe, T.; Traino, A. C.

    2014-01-15

    Purpose: The precise determination of organ mass (m{sub th}) and total number of disintegrations within the thyroid gland (A{sup ~}) are essential for thyroid absorbed-dose calculations for radioiodine therapy. Nevertheless, these parameters may vary according to the method employed for their estimation, thus introducing uncertainty in the estimated thyroid absorbed dose and in any dose–response relationship derived using such estimates. In consideration of these points, thyroid absorbed doses for Graves’ disease (GD) treatment planning were calculated using different approaches to estimating the m{sub th} and the A{sup ~}. Methods: Fifty patients were included in the study. Thyroid{sup 131}I uptake measurements were performed at 2, 6, 24, 48, 96, and 220 h postadministration of a tracer activity in order to estimate the effective half-time (T{sub eff}) of {sup 131}I in the thyroid; the thyroid cumulated activity was then estimated using the T{sub eff} thus determined or, alternatively, calculated by numeric integration of the measured time-activity data. Thyroid mass was estimated by ultrasonography (USG) and scintigraphy (SCTG). Absorbed doses were calculated with the OLINDA/EXM software. The relationships between thyroid absorbed dose and therapy response were evaluated at 3 months and 1 year after therapy. Results: The average ratio (±1 standard deviation) betweenm{sub th} estimated by SCTG and USG was 1.74 (±0.64) and that between A{sup ~} obtained by T{sub eff} and the integration of measured activity in the gland was 1.71 (±0.14). These differences affect the calculated absorbed dose. Overall, therapeutic success, corresponding to induction of durable hypothyroidism or euthyroidism, was achieved in 72% of all patients at 3 months and in 90% at 1 year. A therapeutic success rate of at least 95% was found in the group of patients receiving doses of 200 Gy (p = 0.0483) and 330 Gy (p = 0.0131) when m{sub th} was measured by either USG or SCTG and A

  17. Microdosimetric measurements for neutron-absorbed dose determination during proton therapy

    PubMed Central

    Pérez-Andújar, Angélica; DeLuca, Paul M.; Thornton, Allan F.; Fitzek, Markus; Hecksel, Draik; Farr, Jonathan

    2012-01-01

    This work presents microdosimetric measurements performed at the Midwest Proton Radiotherapy Institute in Bloomington, Indiana, USA. The measurements were done simulating clinical setups with a water phantom and for a variety of stopping targets. The water phantom was irradiated by a proton spread out Bragg peak (SOBP) and by a proton pencil beam. Stopping target measurements were performed only for the pencil beam. The targets used were made of polyethylene, brass and lead. The objective of this work was to determine the neutron-absorbed dose for a passive and active proton therapy delivery, and for the interactions of the proton beam with materials typically in the beam line of a proton therapy treatment nozzle. Neutron doses were found to be higher at 45° and 90° from the beam direction for the SOBP configuration by a factor of 1.1 and 1.3, respectively, compared with the pencil beam. Meanwhile, the pencil beam configuration produced neutron-absorbed doses 2.2 times higher at 0° than the SOBP. For stopping targets, lead was found to dominate the neutron-absorbed dose for most angles due to a large production of low-energy neutrons emitted isotropically. PMID:22334761

  18. Comparison between Three Promising ß-emitting Radionuclides, 67Cu, 47Sc and 161Tb, with Emphasis on Doses Delivered to Minimal Residual Disease

    PubMed Central

    Champion, Christophe; Quinto, Michele A.; Morgat, Clément; Zanotti-Fregonara, Paolo; Hindié, Elif

    2016-01-01

    PURPOSE: Radionuclide therapy is increasingly seen as a promising option to target minimal residual disease. Copper-67, scandium-47 and terbium-161 have a medium-energy β- emission which is similar to that of lutetium-177, but offer the advantage of having diagnostic partner isotopes suitable for pretreatment imaging. The aim of this study was to compare the efficacy of 67Cu, 47Sc and 161Tb to irradiate small tumors. METHODS: The absorbed dose deriving from a homogeneous distribution of 67Cu, 47Sc or 161Tb in water-density spheres was calculated with the Monte Carlo code CELLDOSE. The diameters of the spheres ranged from 5 mm to 10 µm, thus simulating micrometastases or single tumor cells. All electron emissions, including β- spectra, Auger and conversion electrons were taken into account. Because these radionuclides differ in electron energy per decay, the simulations were run assuming that 1 MeV was released per µm3, which would result in a dose of 160 Gy if totally absorbed. RESULTS: The absorbed dose was similar for the three radionuclides in the 5-mm sphere (146-149 Gy), but decreased differently in smaller spheres. In particular, 161Tb delivered higher doses compared to the other radionuclides. For instance, in the 100-µm sphere, the absorbed dose was 24.1 Gy with 67Cu, 14.8 Gy with 47Sc and 44.5 Gy with 161Tb. Auger and conversion electrons accounted for 71% of 161Tb dose. The largest dose differences were found in cell-sized spheres. In the 10-µm sphere, the dose delivered by 161Tb was 4.1 times higher than that from 67Cu and 8.1 times that from 47Sc. CONCLUSION: 161Tb can effectively irradiate small tumors thanks to its decay spectrum that combines medium-energy β- emission and low-energy conversion and Auger electrons. Therefore 161Tb might be a better candidate than 67Cu and 47Sc for treating minimal residual disease in a clinical setting. PMID:27446495

  19. Absorbed Dose Determination Using Experimental and Analytical Predictions of X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Edwards, D. L.; Carruth, Ralph (Technical Monitor)

    2001-01-01

    Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the U.S. Space Shuttle. This series of experiments was named the international space welding experiment (ISWE). The hardware associated with the ISWE was leased to NASA by the Paton Welding Institute (PWI) in Ukraine for ground-based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used thermoluminescence dosimeters (TLD's) shielded with material currently used by astronauts during extravehicular activities to measure the radiation dose. The TLD's were exposed to x-ray radiation generated by operation of the ISWE in-vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore, alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure, then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during actual operation of the ISWE in-vacuum electron beam welding tool. The calculated absorbed dose

  20. An international dosimetry exchange for boron neutron capture therapy. Part I: Absorbed dose measurements.

    PubMed

    Binns, P J; Riley, K J; Harling, O K; Kiger, W S; Munck af Rosenschöld, P M; Giusti, V; Capala, J; Sköld, K; Auterinen, I; Serén, T; Kotiluoto, P; Uusi-Simola, J; Marek, M; Viererbl, L; Spurny, F

    2005-12-01

    An international collaboration was organized to undertake a dosimetry exchange to enable the future combination of clinical data from different centers conducting neutron capture therapy trials. As a first step (Part I) the dosimetry group from the Americas, represented by MIT, visited the clinical centers at Studsvik (Sweden), VTT Espoo (Finland), and the Nuclear Research Institute (NRI) at Rez (Czech Republic). A combined VTT/NRI group reciprocated with a visit to MIT. Each participant performed a series of dosimetry measurements under equivalent irradiation conditions using methods appropriate to their clinical protocols. This entailed in-air measurements and dose versus depth measurements in a large water phantom. Thermal neutron flux as well as fast neutron and photon absorbed dose rates were measured. Satisfactory agreement in determining absorbed dose within the experimental uncertainties was obtained between the different groups although the measurement uncertainties are large, ranging between 3% and 30% depending upon the dose component and the depth of measurement. To improve the precision in the specification of absorbed dose amongst the participants, the individually measured dose components were normalized to the results from a single method. Assuming a boron concentration of 15 microg g(-1) that is typical of concentrations realized clinically with the boron delivery compound boronophenylalanine-fructose, systematic discrepancies in the specification of the total biologically weighted dose of up to 10% were apparent between the different groups. The results from these measurements will be used in future to normalize treatment plan calculations between the different clinical dosimetry protocols as Part II of this study.

  1. Radiation absorbed dose estimates for [1-carbon-11]-glucose in adults: The effects of hyperinsulinemia

    SciTech Connect

    Powers, W.J. |

    1996-10-01

    As preparation for studies of blood-brain glucose transport in diabetes mellitus, radiation absorbed dose estimates from intravenous administration of [1-{sup 11}C]-glucose for 24 internal organs, lens, blood and total body were calculated for three physiologic conditions: euinsulinemic euglycemia, hyperinsulinemic euglycemia and hyperinsulinemic hyperglycemia. Cumulated activities in blood, insulin-independent and insulin-dependent compartments were calculated from blood time-activity curves in normal human volunteers and macaques. Apportionment of cumulated activity to individual organs in insulin-dependent and insulin-independent compartments was based on previously published data. Absorbed doses were calculated with the computer program MIRDOSE 3 for the 70-kg adult phantom. S for blood was calculated separately. The heart wall, lungs and spleen were the organs receiving the highest dose. The effect of hyperinsulinemia was demonstrated by the increase in adsorbed dose to the muscle, heart and blood with a decrease to other internal organs. This effect was more pronounced during hyperinsulinemic hyperglycemia. Hyperinsulinemia produced a decrease in effective dose due to the decrease in cumulated activity in organs with specified weighting factors greater than 0.05. The effective dose per study for [1-{sup 11}C]-glucose is comparable to that reported for 2-deoxy-[2-{sup 18}F]-glucose. 43 refs., 1 fig., 4 tabs.

  2. Determination of the absorbed dose and the average LET of space radiation in dependence on shielding conditions.

    PubMed

    Vana, N; Schoner, W; Noll, M; Fugger, M; Akatov, Y; Shurshakov, V

    1999-01-01

    The HTR method, developed for determination of absorbed dose and average LET of mixed radiation fields in space, was applied during several space missions on space station MIR, space shuttles and satellites. The method utilises the changes of peak height ratios in the glow curves in dependence on the linear energy transfer LET. Due to the small size of the dosemeters the evaluation of the variation of absorbed dose and average LET in dependence on the position of the dosemeters inside the space station is possible. The dose and LET distribution was determined during the experiment ADLET where dosemeters were exposed in two positions with different shielding conditions and during two following experiments (MIR-95, MIR-96) using six positions inside the space station. The results were compared with the shielding conditions of the positions. Calculations of the absorbed dose were carried out for comparison. Results have shown that the average LET increases with increasing absorbing thickness while the absorbed dose decreases.

  3. The Fricke dosimeter as an absorbed dose to water primary standard for Ir-192 brachytherapy

    NASA Astrophysics Data System (ADS)

    El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcolm

    2015-06-01

    The aim of this project was to develop an absorbed dose to water primary standard for Ir-192 brachytherapy based on the Fricke dosimeter. To achieve this within the framework of the existing TG-43 protocol, a determination of the absorbed dose to water at the reference position, D(r0,θ0), was undertaken. Prior to this investigation, the radiation chemical yield of the ferric ions (G-value) at the Ir-192 equivalent photon energy (0.380 MeV) was established by interpolating between G-values obtained for Co-60 and 250 kV x-rays. An irradiation geometry was developed with a cylindrical holder to contain the Fricke solution and allow irradiations in a water phantom to be conducted using a standard Nucletron microSelectron V2 HDR Ir-192 afterloader. Once the geometry and holder were optimized, the dose obtained with the Fricke system was compared to the standard method used in North America, based on air-kerma strength. Initial investigations focused on reproducible positioning of the ring-shaped holder for the Fricke solution with respect to the Ir-192 source and obtaining an acceptable type A uncertainty in the optical density measurements required to yield the absorbed dose. Source positioning was found to be reproducible to better than 0.3 mm, and a careful cleaning and control procedure reduced the variation in optical density reading due to contamination of the Fricke solution by the PMMA holder. It was found that fewer than 10 irradiations were required to yield a type A standard uncertainty of less than 0.5%. Correction factors to take account of the non-water components of the geometry and the volume averaging effect of the Fricke solution volume were obtained from Monte Carlo calculations. A sensitivity analysis showed that the dependence on the input data used (e.g. interaction cross-sections) was small with a type B uncertainty for these corrections estimated to be 0.2%. The combined standard uncertainty in the determination of absorbed dose to water

  4. The Fricke dosimeter as an absorbed dose to water primary standard for Ir-192 brachytherapy.

    PubMed

    El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcolm

    2015-06-01

    The aim of this project was to develop an absorbed dose to water primary standard for Ir-192 brachytherapy based on the Fricke dosimeter. To achieve this within the framework of the existing TG-43 protocol, a determination of the absorbed dose to water at the reference position, D(r0,θ0), was undertaken. Prior to this investigation, the radiation chemical yield of the ferric ions (G-value) at the Ir-192 equivalent photon energy (0.380 MeV) was established by interpolating between G-values obtained for Co-60 and 250 kV x-rays.An irradiation geometry was developed with a cylindrical holder to contain the Fricke solution and allow irradiations in a water phantom to be conducted using a standard Nucletron microSelectron V2 HDR Ir-192 afterloader. Once the geometry and holder were optimized, the dose obtained with the Fricke system was compared to the standard method used in North America, based on air-kerma strength.Initial investigations focused on reproducible positioning of the ring-shaped holder for the Fricke solution with respect to the Ir-192 source and obtaining an acceptable type A uncertainty in the optical density measurements required to yield the absorbed dose. Source positioning was found to be reproducible to better than 0.3 mm, and a careful cleaning and control procedure reduced the variation in optical density reading due to contamination of the Fricke solution by the PMMA holder. It was found that fewer than 10 irradiations were required to yield a type A standard uncertainty of less than 0.5%.Correction factors to take account of the non-water components of the geometry and the volume averaging effect of the Fricke solution volume were obtained from Monte Carlo calculations. A sensitivity analysis showed that the dependence on the input data used (e.g. interaction cross-sections) was small with a type B uncertainty for these corrections estimated to be 0.2%.The combined standard uncertainty in the determination of absorbed dose to water at

  5. Deterministic absorbed dose estimation in computed tomography using a discrete ordinates method

    SciTech Connect

    Norris, Edward T.; Liu, Xin; Hsieh, Jiang

    2015-07-15

    Purpose: Organ dose estimation for a patient undergoing computed tomography (CT) scanning is very important. Although Monte Carlo methods are considered gold-standard in patient dose estimation, the computation time required is formidable for routine clinical calculations. Here, the authors instigate a deterministic method for estimating an absorbed dose more efficiently. Methods: Compared with current Monte Carlo methods, a more efficient approach to estimating the absorbed dose is to solve the linear Boltzmann equation numerically. In this study, an axial CT scan was modeled with a software package, Denovo, which solved the linear Boltzmann equation using the discrete ordinates method. The CT scanning configuration included 16 x-ray source positions, beam collimators, flat filters, and bowtie filters. The phantom was the standard 32 cm CT dose index (CTDI) phantom. Four different Denovo simulations were performed with different simulation parameters, including the number of quadrature sets and the order of Legendre polynomial expansions. A Monte Carlo simulation was also performed for benchmarking the Denovo simulations. A quantitative comparison was made of the simulation results obtained by the Denovo and the Monte Carlo methods. Results: The difference in the simulation results of the discrete ordinates method and those of the Monte Carlo methods was found to be small, with a root-mean-square difference of around 2.4%. It was found that the discrete ordinates method, with a higher order of Legendre polynomial expansions, underestimated the absorbed dose near the center of the phantom (i.e., low dose region). Simulations of the quadrature set 8 and the first order of the Legendre polynomial expansions proved to be the most efficient computation method in the authors’ study. The single-thread computation time of the deterministic simulation of the quadrature set 8 and the first order of the Legendre polynomial expansions was 21 min on a personal computer

  6. High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin's Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes

    SciTech Connect

    Rajendran, Joseph G.; Fisher, Darrell R.; Gopal, A K.; Durack, L. D.; Press, O. W.; Eary, Janet F.

    2004-06-01

    Radioimmunotherapy (RIT) using 131I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on radiation absorbed close to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific absorbed dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 131I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar -camera images and whole-body Nal probe counts were obtained to estimate 131I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean radiation absorbed doses (in mGy/MBq) for our data using the MIRD model were lungs= 1.67; liver= 1.03; kidneys= 1.08; spleen= 2.67; and whole body= 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs= 1.30; liver= 0.92; kidneys= 0.76; spleen= 1.40; and whole body= 0.22. We determined the following correlation coefficients between the 2 methods for the various organs; lungs, 0.49; (P= 0.0001); liver, 0.64 (P= 0.004); kidneys, 0.45 (P= 0.0001), for the residence times. For therapy, patients received mean 131I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes--a statistically significant difference (P= 0.0001). Conclusion: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated radiation dose to the dose-limiting normal organ. This work provides a simplified method for calculating patient-specific radiation

  7. The lateral plane delivers higher dose than the frontal plane in biplane cardiac catheterization systems.

    PubMed

    Aldoss, Osamah; Patel, Sonali; Harris, Kyle; Divekar, Abhay

    2015-06-01

    The objective of the study is to compare radiation dose between the frontal and lateral planes in a biplane cardiac catheterization laboratory. Tube angulation progressively increases patient and operator radiation dose in single-plane cardiac catheterization laboratories. This retrospective study captured biplane radiation dose in a pediatric cardiac catheterization laboratory between April 2010 and January 2014. Raw and time-indexed fluoroscopic, cineangiographic and total (fluoroscopic + cineangiographic) air kerma (AK, mGy) and kerma area product (PKA, µGym(2)/Kg) for each plane were compared. Data for 716 patients were analyzed: 408 (56.98 %) were male, the median age was 4.86 years, and the median weight was 17.35 kg. Although median beam-on time (minutes) was 4.2 times greater in the frontal plane, there was no difference in raw median total PKA between the two planes. However, when indexed to beam-on time, the lateral plane had a higher median-indexed fluoroscopic (0.75 vs. 1.70), cineangiographic (16.03 vs. 24.92), and total (1.43 vs. 5.15) PKA (p < 0.0001). The median time-indexed total PKA in the lateral plane is 3.6 times the frontal plane. This is the first report showing that the lateral plane delivers a higher dose than the frontal plane per unit time. Operators should consciously reduce the lateral plane beam-on time and incorporate this practice in radiation reduction protocols.

  8. Doses delivered to normal brain under different treatment protocols at Brookhaven National Laboratory

    SciTech Connect

    Capala, J.; Coderre, J.A.; Liu, H.B.

    1996-12-31

    As of October 31, 1996, 23 glioblastoma multiforme patients underwent BNCT under several treatment protocols at the Brookhaven Medical Research Reactor. For treatment planning and dosimetry purposes, these protocols may be divided into four groups. The first group comprises protocols that used an 8-cm collimator and allowed a peak normal brain dose of 10.5 Gy-Eq to avolume of 1 cm{sup 3} were the thermal neutron flux was maximal (even if it happened to be in the tumor volume). The second group differs from the first in that it allowed a peak normal brain dose of 12.6 Gy-Eq. The protocols of the third and fourth groups allowed the prescribed peak normal brain dose of 12.6 Gy-Eq to be outside of the tumor volume, used a 12-cm collimator and, respectively, uni- or bilateral irradiations. We describe the treatment planning procedures and report the doses delivered to various structures of the brain.

  9. SU-E-T-517: Analytic Formalism to Compute in Real Time Dose Distributions Delivered by HDR Units

    SciTech Connect

    Pokhrel, S; Loyalka, S; Palaniswaamy, G; Rangaraj, D; Izaguirre, E

    2014-06-01

    Purpose: Develop an analytical algorithm to compute the dose delivered by Ir-192 dwell positions with high accuracy using the 3-dimensional (3D) dose distribution of an HDR source. Using our analytical function, the dose delivered by an HDR unit as treatment progresses can be determined using the actual delivered temporal and positional data of each individual dwell. Consequently, true delivered dose can be computed when each catheter becomes active. We hypothesize that the knowledge of such analytical formulation will allow developing HDR systems with a real time treatment evaluation tool to avoid mistreatments. Methods: In our analytic formulation, the dose is computed by using the full anisotropic function data of the TG 43 formalism with 3D ellipsoidal function. The discrepancy between the planned dose and the delivered dose is computed using an analytic perturbation method over the initial dose distribution. This methodology speeds up the computation because only changes in dose discrepancies originated by spatial and temporal deviations are computed. A dose difference map at the point of interest is obtained from these functions and this difference can be shown during treatment in real time to examine the treatment accuracy. Results: We determine the analytical solution and a perturbation function for the 3 translational 3 rotational, and 1D temporal errors in source distributions. The analytic formulation is a sequence of simple equations that can be processed in any modern computer in few seconds. Because computations are based in an analytical solution, small deviations of the dose when sub-millimeter positional changes occur can be detected. Conclusions: We formulated an analytical method to compute 4D dose distributions and dose differences based on an analytical solution and perturbations to the original dose. This method is highly accurate and can be.

  10. Absorbed doses and energy imparted from radiographic examination of velopharyngeal function during speech

    SciTech Connect

    Isberg, A.; Julin, P.; Kraepelien, T.; Henrikson, C.O. )

    1989-04-01

    Absorbed doses of radiation were measured by thermoluminescent dosimeters (TLDs) using a skull phantom during simulated cinefluorographic and videofluorographic examination of velopharyngeal function in frontal and lateral projections. Dosages to the thyroid gland, the parotid gland, the pituitary gland, and ocular lens were measured. Radiation dosage was found to be approximately 10 times less for videofluoroscopy when compared with that of cinefluoroscopy. In addition, precautionary measures were found to reduce further the exposure of radiation-sensitive tissues. Head fixation and shielding resulted in dose reduction for both video- and cinefluoroscopy. Pulsing exposure for cinefluoroscopy also reduced the dosage.

  11. Equilibration of a Graphite Absorbed-Dose Calorimeter and the Quasi-Isothermal Mode of Operation

    NASA Astrophysics Data System (ADS)

    Janssens, A.; Cottens, E.; Paulsen, A.; Poffijn, A.

    1986-01-01

    From a mathematical model of a three-body absorbed-dose calorimeter a procedure for achieving thermal equilibrium is developed which uses calculational methods to determine the exact amount and timing of electrical energy to be dissipated in the calorimetric bodies. This procedure is applied to the quasi-isothermal mode of operation in which a radiation beam and equivalent electrical heating are alternately used to keep the calorimetric bodies at temperatures as constant as possible. Measurements of the dose rate of a 60Co beam in graphite using this technique are reported.

  12. Mycosis Fungoides electron beam absorbed dose distribution using Fricke xylenol gel dosimetry

    NASA Astrophysics Data System (ADS)

    da Silveira, Michely C.; Sampaio, Francisco G. A.; Petchevist, Paulo C. D.; de Oliveira, André L.; Almeida, Adelaide de

    2011-12-01

    Radiotherapy uses ionizing radiation to destroy tumor cells. The absorbed dose control in the target volume is realized through radiation sensors, such as Fricke dosimeters and radiochromic film, which permit to realize bi-dimensional evaluations at once and because of that, they will be used in this study as well. Among the several types of cancer suitable for ionizing radiation treatment, the Mycosis Fungoides, a lymphoma that spreads on the skin surface and depth, requires for its treatment total body irradiation by high-energy electrons. In this work the Fricke xylenol gel (FXG) was used in order to obtain information about the absorbed dose distribution induced by the electron interactions with the irradiated tissues and to control this type of treatment. FXG can be considered as an alternative dosimeter, since up to now only films have been used. FXG sample cuvettes, simulating two selected tomos (cranium and abdomen) of the Rando anthropomorphic phantom, were positioned along with radiochromic films for comparison. The phantom was subjected to Stanford total body irradiation using 6 MeV electrons. Tomographic images were acquired for both dosimeters and evaluated through horizontal and vertical profiles along the tomographic centers. These profiles were obtained through a Matlab routine developed for this purpose. From the obtained results, one could infer that, for a superficial and internal patient irradiation, the FXG dosimeter showed an absorbed dose distribution similar to the one of the film. These results can validate the FXG dosimeter as an alternative dosimeter for the Mycosis Fungoides treatment planning.

  13. Verification of absorbed dose using diodes in cobalt-60 radiation therapy.

    PubMed

    Gadhi, Muhammad Asghar; Fatmi, Shahab; Chughtai, Gul M; Arshad, Muhammad; Shakil, Muhammad; Rahmani, Uzma Mahmood; Imran, Malik Younas; Buzdar, Saeed Ahmad

    2016-03-01

    The objective of this work was to enhance the quality and safety of dose delivery in the practice of radiation oncology. To achieve this goal, the absorbed dose verification program was initiated by using the diode in vivo dosimetry (IVD) system (for entrance and exit). This practice was implemented at BINO, Bahawalpur, Pakistan. Diodes were calibrated for making absorbed dose measurements. Various correction factors (SSD, dose non-linearity, field size, angle of incidence, and wedge) were determined for diode IVD system. The measurements were performed in phantom in order to validate the IVD procedure. One hundred and nineteen patients were monitored and 995 measurements were performed. For phantom, the percentage difference between measured and calculated dose for entrance setting remained within ±2% and for exit setting ±3%. For patient measurements, the percentage difference between measured and calculated dose remained within ±5% for entrance/open fields and ±7% for exit/wedge/oblique fields. One hundred and nineteen patients and 995 fields have been monitored during the period of 6 months. The analysis of all available measurements gave a mean percent deviation of ±1.19% and standard deviation of ±2.87%. Larger variations have been noticed in oblique, wedge and exit measurements. This investigation revealed that clinical dosimetry using diodes is simple, provides immediate results and is a useful quality assurance tool for dose delivery. It has enhanced the quality of radiation dose delivery and increased/improved the reliability of the radiation therapy practice in BINO. PMID:26753835

  14. Parotid Glands Dose-Effect Relationships Based on Their Actually Delivered Doses: Implications for Adaptive Re-Planning in Radiotherapy of Head and Neck Cancer

    PubMed Central

    Hunter, Klaudia U.; Fernandes, Laura; Vineberg, Karen A.; McShan, Daniel; Antonuk, Alan E.; Cornwall, Craig; Feng, Mary; Schipper, Mathew; Balter, James; Eisbruch, Avraham

    2013-01-01

    Purpose Doses actually delivered to the parotid glands during radiotherapy often exceed planned doses. We hypothesized that the delivered doses correlate better with parotid salivary output than the planned doses, used in all previous studies, and that determining these correlations will help decisions regarding adaptive re-planning (ART) aimed at reducing the delivered doses. Methods and Materials Prospective study: oropharyngeal cancer patients treated definitively with chemo-irradiation underwent daily cone beam CT (CBCT) with clinical set-up alignment based on C2 posterior edge. Parotid glands in the CBCTs were aligned by deformable registration to calculate cumulative delivered doses. Stimulated salivary flow rates were measured separately from each parotid gland pretherapy and periodically posttherapy. Results 36 parotid glands of 18 patients were analyzed. Average mean planned doses was 32 Gy and differences from planned to delivered mean gland doses were −4.9 to +8.4 Gy, median difference +2.2 Gy in glands whose delivered doses increased relative to planned. Both planned and delivered mean doses were significantly correlated with post-treatment salivary outputs at almost all post-therapy time points, without statistically significant differences in the correlations. Large dispersions [on average, standard deviation (SD) 3.6 Gy] characterized the dose/effect relationships for both. The differences between the cumulative delivered doses and planned doses were evident already at first fraction (r=0.92, p<0.0001) due to complex set-up deviations, e.g. rotations and neck articulations, uncorrected by the translational clinical alignments. Conclusions After daily translational set-up corrections, differences between planned and delivered doses in most glands were small relative to the SDs of the dose/saliva data, suggesting that ART is not likely to gain measurable salivary output improvement in most cases. These differences were observed already at first

  15. Fine-Resolution Voxel S Values for Constructing Absorbed Dose Distributions at Variable Voxel Size

    PubMed Central

    Dieudonné, Arnaud; Hobbs, Robert F.; Bolch, Wesley E.; Sgouros, George; Gardin, Isabelle

    2010-01-01

    This article presents a revised voxel S values (VSVs) approach for dosimetry in targeted radiotherapy, allowing dose calculation for any voxel size and shape of a given SPECT or PET dataset. This approach represents an update to the methodology presented in MIRD pamphlet no. 17. Methods VSVs were generated in soft tissue with a fine spatial sampling using the Monte Carlo (MC) code MCNPX for particle emissions of 9 radionuclides: 18F, 90Y, 99mTc, 111In, 123I, 131I, 177Lu, 186Re, and 201Tl. A specific resampling algorithm was developed to compute VSVs for desired voxel dimensions. The dose calculation was performed by convolution via a fast Hartley transform. The fine VSVs were calculated for cubic voxels of 0.5 mm for electrons and 1.0 mm for photons. Validation studies were done for 90Y and 131I VSV sets by comparing the revised VSV approach to direct MC simulations. The first comparison included 20 spheres with different voxel sizes (3.8–7.7 mm) and radii (4–64 voxels) and the second comparison a hepatic tumor with cubic voxels of 3.8 mm. MC simulations were done with MCNPX for both. The third comparison was performed on 2 clinical patients with the 3D-RD (3-Dimensional Radiobiologic Dosimetry) software using the EGSnrc (Electron Gamma Shower National Research Council Canada)-based MC implementation, assuming a homogeneous tissue-density distribution. Results For the sphere model study, the mean relative difference in the average absorbed dose was 0.20% ± 0.41% for 90Y and −0.36% ± 0.51% for 131I (n = 20). For the hepatic tumor, the difference in the average absorbed dose to tumor was 0.33% for 90Y and −0.61% for 131I and the difference in average absorbed dose to the liver was 0.25% for 90Y and −1.35% for 131I. The comparison with the 3D-RD software showed an average voxel-to-voxel dose ratio between 0.991 and 0.996. The calculation time was below 10 s with the VSV approach and 50 and 15 h with 3D-RD for the 2 clinical patients. Conclusion This new

  16. In vivo absorbed dose measurements in mammography using a new real-time luminescence technique.

    PubMed

    Aznar, M C; Hemdal, B; Medin, J; Marckmann, C J; Andersen, C E; Bøtter-Jensen, L; Andersson, I; Mattsson, S

    2005-04-01

    A dosimetry system based on radioluminescence (RL) and optically stimulated luminescence (OSL) from carbon doped aluminium oxide (Al2O3:C) crystals was developed for in vivo absorbed dose measurements in mammography. A small cylindrical crystal of Al2O3:C (diameter 0.48 mm and length 2 mm) was coupled to the end of a 1 mm diameter optical fibre cable. Owing to their small size and characteristic shape, these probes can be placed on the body surface in the field of view during the examination, without compromising the reading of the mammogram. Our new technique was tested with a mammography unit (Siemens Mammomat 3000) and screen-film technique over a range of clinically relevant X-ray energies. The results were compared with those obtained from an ionization chamber usually used for the determination of absorbed dose in mammography. The reproducibility of measurements was around 3% (1 standard deviation) at 4.5 mGy for both RL and OSL data. The dose response was found to be linear between 4.5 mGy and 30 mGy. The energy dependence of the system is around 18% between 23 kV and 35 kV. In vivo measurements were performed during three patient examinations. It was shown that entrance and exit doses could be measured. The presence of the small probes did not significantly interfere with the diagnostic quality of the images. Entrance doses estimated by RL/OSL results agreed within 3% with entrance surface dose values calculated from the ionization chamber measurements. These results indicate a considerable potential for use in routine control and in vivo dose measurements in mammography.

  17. The estimation of absorbed dose rates for non-human biota : an extended inter-comparison.

    SciTech Connect

    Batlle, J. V. I.; Beaugelin-Seiller, K.; Beresford, N. A.; Copplestone, D.; Horyna, J.; Hosseini, A.; Johansen, M.; Kamboj, S.; Keum, D.-K.; Kurosawa, N.; Newsome, L.; Olyslaegers, G.; Vandenhove, H.; Ryufuku, S.; Lynch, S. V.; Wood, M. D.; Yu, C.

    2011-05-01

    An exercise to compare 10 approaches for the calculation of unweighted whole-body absorbed dose rates was conducted for 74 radionuclides and five of the ICRP's Reference Animals and Plants, or RAPs (duck, frog, flatfish egg, rat and elongated earthworm), selected for this exercise to cover a range of body sizes, dimensions and exposure scenarios. Results were analysed using a non-parametric method requiring no specific hypotheses about the statistical distribution of data. The obtained unweighted absorbed dose rates for internal exposure compare well between the different approaches, with 70% of the results falling within a range of variation of {+-}20%. The variation is greater for external exposure, although 90% of the estimates are within an order of magnitude of one another. There are some discernible patterns where specific models over- or under-predicted. These are explained based on the methodological differences including number of daughter products included in the calculation of dose rate for a parent nuclide; source-target geometry; databases for discrete energy and yield of radionuclides; rounding errors in integration algorithms; and intrinsic differences in calculation methods. For certain radionuclides, these factors combine to generate systematic variations between approaches. Overall, the technique chosen to interpret the data enabled methodological differences in dosimetry calculations to be quantified and compared, allowing the identification of common issues between different approaches and providing greater assurance on the fundamental dose conversion coefficient approaches used in available models for assessing radiological effects to biota.

  18. The estimation of absorbed dose rates for non-human biota: an extended intercomparison.

    PubMed

    Vives i Batlle, J; Beaugelin-Seiller, K; Beresford, N A; Copplestone, D; Horyna, J; Hosseini, A; Johansen, M; Kamboj, S; Keum, D-K; Kurosawa, N; Newsome, L; Olyslaegers, G; Vandenhove, H; Ryufuku, S; Vives Lynch, S; Wood, M D; Yu, C

    2011-05-01

    An exercise to compare 10 approaches for the calculation of unweighted whole-body absorbed dose rates was conducted for 74 radionuclides and five of the ICRP's Reference Animals and Plants, or RAPs (duck, frog, flatfish egg, rat and elongated earthworm), selected for this exercise to cover a range of body sizes, dimensions and exposure scenarios. Results were analysed using a non-parametric method requiring no specific hypotheses about the statistical distribution of data. The obtained unweighted absorbed dose rates for internal exposure compare well between the different approaches, with 70% of the results falling within a range of variation of ±20%. The variation is greater for external exposure, although 90% of the estimates are within an order of magnitude of one another. There are some discernible patterns where specific models over- or under-predicted. These are explained based on the methodological differences including number of daughter products included in the calculation of dose rate for a parent nuclide; source-target geometry; databases for discrete energy and yield of radionuclides; rounding errors in integration algorithms; and intrinsic differences in calculation methods. For certain radionuclides, these factors combine to generate systematic variations between approaches. Overall, the technique chosen to interpret the data enabled methodological differences in dosimetry calculations to be quantified and compared, allowing the identification of common issues between different approaches and providing greater assurance on the fundamental dose conversion coefficient approaches used in available models for assessing radiological effects to biota. PMID:21113609

  19. A geochemical assessment of terrestrial gamma-ray absorbed dose rates.

    PubMed

    Wollenberg, H A; Smith, A R

    1990-02-01

    A survey of the geochemical literature and unpublished data has resulted in the classification of the concentrations of the naturally occurring radioelements U, Th, and K by their associated rock types. A data base of over 2500 entries has been compiled, permitting calculation of terrestrial gamma-ray absorbed dose rates. The general lithology of terrains may be distinguished by their radioelement ratios, relative abundances, and total gamma radioactivities. The gamma-ray absorbed dose rates in air above igneous rocks generally vary with their silica contents, and with the exception of shale, sedimentary rocks have lower K:U and K:Th ratios than most igneous rocks. The appreciable difference between the overall mean terrestrial gamma-ray dose rate for rock of the continental surface (approximately 7 X 10(-8) Gy h-1) and the mean dose rate from field measurements over soil (approximately 5 X 10(-8) Gy h-1) is explained by the substantial differences between radioelement concentrations of soil and rock, differences that may vary markedly with rock type.

  20. Estimation of radiation absorbed doses to the red marrow in radioimmunotherapy

    SciTech Connect

    Macey, D.J.; DeNardo, S.J.; DeNardo, G.L.; DeNardo, D.A.; Sui Shen

    1995-02-01

    Myelotoxicity is the dose-limiting factor in radioimmunotherapy. Traditional methods most commonly used to estimate the radiation adsorbed dose to the bone marrow of patients consider contribution from radionuclide in the blood and/or total body. Targeted therapies, such as radioimmunotherapy, add a third potential source for radiation to the bone marrow because the radiolabeled targeting molecules can accumulate specifically on malignant target cells infiltrating the bone marrow. A non-invasive method for estimating the radiation absorbed dose to the red marrow of patients who have received radiolabeled monoclonal antibodies (MoAb) has been developed and explored. The method depends on determining the cumulated activity in three contributing sources: (1) marrow; (2) blood; and (3) total body. The novel aspect of this method for estimating marrow radiation dose is derivation of the radiation dose for the entire red marrow from radiation dose estimates obtained by detection of cumulated activity in three lumbar vertebrae using a gamma camera. Contributions to the marrow radiation dose form marrow, blood, and total body cumulated activity were determined for patients who received an I-131 labeled MoAb, Lym-1, that reacts with malignant B-lymphocytes of chronic lymphocytic leukemia and nonHodgkin`s lymphoma. Six patients were selected for illustrative purposes because their vertebrae were readily visualized on lumbar images. 32 refs., 6 figs., 1 tab.

  1. Assessment of indoor absorbed gamma dose rate from natural radionuclides in concrete by the method of build-up factors.

    PubMed

    Manić, Vesna; Nikezic, Dragoslav; Krstic, Dragana; Manić, Goran

    2014-12-01

    The specific absorbed gamma dose rates, originating from natural radionuclides in concrete, were calculated at different positions of a detection point inside the standard room, as well as inside an example room. The specific absorbed dose rates corresponding to a wall with arbitrary dimensions and thickness were also evaluated, and appropriate fitting functions were developed, enabling dose rate calculation for most realistic rooms. In order to make calculation simpler, the expressions fitting the exposure build-up factors for whole (238)U and (232)Th radionuclide series and (40)K were derived in this work, as well as the specific absorbed dose rates from a point source in concrete. Calculated values of the specific absorbed dose rates at the centre point of the standard room for (238)U, (232)Th and (40)K are in the ranges of previously obtained data.

  2. Calculation of absorbed doses to water pools in severe accident sequences

    SciTech Connect

    Weber, C.F.

    1991-12-01

    A methodology is presented for calculating the radiation dose to a water pool from the decay of uniformly distributed nuclides in that pool. Motivated by the need to accurately model radiolysis reactions of iodine, direct application is made to fission product sources dissolved or suspended in containment sumps or pools during a severe nuclear reactor accident. Two methods of calculating gamma absorption are discussed - one based on point-kernal integration and the other based on Monte Carlo techniques. Using least-squares minimization, the computed results are used to obtain a correlation that relates absorbed dose to source energy and surface-to-volume ratio of the pool. This correlation is applied to most relevant fission product nuclides and used to actually calculate transient sump dose rate in a pressurized-water reactor (PWR) severe accident sequence.

  3. Effect of gamma ray absorbed dose on the FET transistor parameters

    NASA Astrophysics Data System (ADS)

    Eslami, Baharak; Ashrafi, Saleh

    This article tries to explain a modified method on dosimetry, based on electronic solid state including MOSFET (metal oxide semiconductor field effect) transistors. For this purpose, behavior of two models of MOSFETs has been studied as a function of the absorbed dose. The MOSFETs were irradiated at room temperature by 137Cs gamma ray source in the dose range of 1-5 Gy. Threshold voltage variation of investigated samples has been studied based on their transfer characteristic curves (TF) and also using the readout circuit (RC). For evaluation of laboratory samples sensitivity at different operating conditions, different biases were applied on the gate. In practical applications of radiation dosimetry, a significant change occurs in the threshold voltage of irradiated MOSFETs. And sensitivity of these MOSFETs is increased with increasing the bias values. Therefore, these transistors can be excellent candidates as low-cost sensors for systems that are capable of measuring gamma radiation dose.

  4. Absorbed dose determination using experimental and analytical predictions of x-ray spectra

    NASA Astrophysics Data System (ADS)

    Edwards, David Lee

    1999-10-01

    Electron beam welding in a vacuum is a technology that NASA is investigating as a joining technique for manufacture of space structures. The interaction of energetic electrons with metal produces x-rays. This investigation characterizes the x-ray environment due to operation of an in-vacuum electron beam welding tool and provides recommendations for adequate radiation shielding for astronauts performing the in-vacuum electron beam welding. NASA, in a joint venture with the Russian Space Agency, was scheduled to perform a series of welding in space experiments on board the United States Space Shuttle. This series of experiments was named the International Space Welding Experiment (ISWE). The hardware associated with the ISWE was leased to NASA, by the Paton Welding Institute (PWI) in Ukraine, for ground based welding experiments in preparation for flight. Two ground tests were scheduled, using the ISWE electron beam welding tool, to characterize the radiation exposure to an astronaut during the operation of the ISWE. These radiation exposure tests used Thermoluminescence Dosimeters (TLD's) shielded with material currently used by astronauts during Extra Vehicular Activities (EVA) to measure the radiation dose. The TLD's were exposed to x- ray radiation generated by operation of the ISWE in- vacuum electron beam welding tool. This investigation was the first known application of TLD's to measure absorbed dose from x-rays of energy less than 10 keV. The ISWE hardware was returned to Ukraine before the issue of adequate shielding for the astronauts was completely verified. Therefore alternate experimental and analytical methods were developed to measure and predict the x-ray spectral and intensity distribution generated by ISWE electron beam impact with metal. These x-ray spectra were normalized to an equivalent ISWE exposure then used to calculate the absorbed radiation dose to astronauts. These absorbed dose values were compared to TLD measurements obtained during

  5. Relative Efficiency of TLD-100 to Linear Energy Transfer Radiation: Correction to Astronaut Absorbed Dose

    NASA Technical Reports Server (NTRS)

    Badhwar, Gautam D.; Cash, B. L.; Semones, E. J.; Yasuda, H.; Fujitaka, K.

    1999-01-01

    Response of thermoluminescent detectors (TLD-100) to high linear energy transfer (LET) particles has been studied using helium, carbon, silicon, and iron ions from the Heavy Ion Medical Accelerator at Chiba (Japan), iron ions from the Brookhaven National Laboratory (NY) Alternate Gradient Synchrotron, and 53, 134, 185, and 232 MeV protons from the Loma Linda accelerator. Using the measured relative (to (137)Cs dose efficiency, and measured LET spectra from a tissue equivalent proportional counter (TEPC) on 20 Space Shuttle flights, and 7 Mir flights, the underestimation of absorbed dose by these detectors has been evaluated. The dose underestimation is between 15-20% depending upon the flight inclination and shielding location. This has been confirmed by direct correlation of measured dose by TEPC and TLD-100 at a low shielded location in the Shuttle mid-deck. A comparison of efficiency- LET data with a compilation of similar data from TLD-700, shows that shapes of the two curves are nearly identical, but that the TLD-100 curve is systematically lower by about 13%, and is the major cause of dose underestimation. These results strongly suggest that TLDs used for crew dose estimation be regularly calibrated using heavy ions.

  6. Relative Efficiency of TLD-100 to High Linear Energy Transfer Radiation: Correction to Astronaut Absorbed Dose

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Cash, B. L.; Semones, E. J.; Yasuda, H.; Fujitaka, K.

    1999-01-01

    Response of thermoluminescent detectors (TLD-100) to high linear energy transfer (LET) particles has been studied using helium, carbon, silicon, and iron ions from the Heavy Ion Medical Accelerator at Chiba (Japan), iron ions from the Brookhaven National Laboratory (NY) Alternate Gradient Synchrotron, and 53, 134, 185, and 232 MeV protons from the Loma Linda accelerator. Using the measured relative (to 137Cs) dose efficiency, and measured LET spectra from a tissue equivalent proportional counter (TEPC) on 20 Space Shuttle flights, and 7 Mir flights, the underestimation of absorbed dose by these detectors has been evaluated. The dose underestimation is between 15-20% depending upon the flight inclination and shielding location. This has been confirmed by direct correlation of measured dose by TEPC and TLD-100 at a low shielded location in the Shuttle mid-deck. A comparison of efficiency- LET data with a compilation of similar data from TLD-700, shows that shapes of the two curves are nearly identical, but that the TLD-100 curve is systematically lower by about 13%, and is the major cause of dose underestimation. These results strongly suggest that TLDs used for crew dose estimation be regularly calibrated using heavy ions.

  7. Response functions for computing absorbed dose to skeletal tissues from photon irradiation—an update

    NASA Astrophysics Data System (ADS)

    Johnson, Perry B.; Bahadori, Amir A.; Eckerman, Keith F.; Lee, Choonsik; Bolch, Wesley E.

    2011-04-01

    A comprehensive set of photon fluence-to-dose response functions (DRFs) is presented for two radiosensitive skeletal tissues—active and total shallow marrow—within 15 and 32 bone sites, respectively, of the ICRP reference adult male. The functions were developed using fractional skeletal masses and associated electron-absorbed fractions as reported for the UF hybrid adult male phantom, which in turn is based upon micro-CT images of trabecular spongiosa taken from a 40 year male cadaver. The new DRFs expand upon both the original set of seven functions produced in 1985, and a 2007 update calculated under the assumption of secondary electron escape from spongiosa. In this study, it is assumed that photon irradiation of the skeleton will yield charged particle equilibrium across all spongiosa regions at energies exceeding 200 keV. Kerma coefficients for active marrow, inactive marrow, trabecular bone and spongiosa at higher energies are calculated using the DRF algorithm setting the electron-absorbed fraction for self-irradiation to unity. By comparing kerma coefficients and DRF functions, dose enhancement factors and mass energy-absorption coefficient (MEAC) ratios for active marrow to spongiosa were derived. These MEAC ratios compared well with those provided by the NIST Physical Reference Data Library (mean difference of 0.8%), and the dose enhancement factors for active marrow compared favorably with values calculated in the well-known study published by King and Spiers (1985 Br. J. Radiol. 58 345-56) (mean absolute difference of 1.9 percentage points). Additionally, dose enhancement factors for active marrow were shown to correlate well with the shallow marrow volume fraction (R2 = 0.91). Dose enhancement factors for the total shallow marrow were also calculated for 32 bone sites representing the first such derivation for this target tissue.

  8. Impact of Gastric Filling on Radiation Dose Delivered to Gastroesophageal Junction Tumors

    SciTech Connect

    Bouchard, Myriam; McAleer, Mary Frances; Starkschall, George

    2010-05-01

    Purpose: This study examined the impact of gastric filling variation on target coverage of gastroesophageal junction (GEJ) tumors in three-dimensional conformal radiation therapy (3DCRT), intensity-modulated radiation therapy (IMRT), or IMRT with simultaneous integrated boost (IMRT-SIB) plans. Materials and Methods: Eight patients previously receiving radiation therapy for esophageal cancer had computed tomography (CT) datasets acquired with full stomach (FS) and empty stomach (ES). We generated treatment plans for 3DCRT, IMRT, or IMRT-SIB for each patient on the ES-CT and on the FS-CT datasets. The 3DCRT and IMRT plans were planned to 50.4 Gy to the clinical target volume (CTV), and the same for IMRT-SIB plus 63.0 Gy to the gross tumor volume (GTV). Target coverage was evaluated using dose-volume histogram data for patient treatments simulated with ES-CT sets, assuming treatment on an FS for the entire course, and vice versa. Results: FS volumes were a mean of 3.3 (range, 1.7-7.5) times greater than ES volumes. The volume of the GTV receiving >=50.4 Gy (V{sub 50.4Gy}) was 100% in all situations. The planning GTV V{sub 63Gy} became suboptimal when gastric filling varied, regardless of whether simulation was done on the ES-CT or the FS-CT set. Conclusions: Stomach filling has a negligible impact on prescribed dose delivered to the GEJ GTV, using either 3DCRT or IMRT planning. Thus, local relapses are not likely to be related to variations in gastric filling. Dose escalation for GEJ tumors with IMRT-SIB may require gastric filling monitoring.

  9. Mercury exposure from dental amalgam fillings: absorbed dose and the potential for adverse health effects.

    PubMed

    Mackert, J R; Berglund, A

    1997-01-01

    This review examines the question of whether adverse health effects are attributable to amalgam-derived mercury. The issue of absorbed dose of mercury from amalgam is addressed first. The use of intra-oral Hg vapor measurements to estimate daily uptake must take into account the differences between the collection volume and flow rate of the measuring instrument and the inspiratory volume and flow rate of air through the mouth during inhalation of a single breath. Failure to account for these differences will result in substantial overestimation of the absorbed dose. Other factors that must be considered when making estimates of Hg uptake from amalgam include the accurate measurement of baseline (unstimulated) mercury release rates and the greater stimulation of Hg release afforded by chewing gum relative to ordinary food. The measured levels of amalgam-derived mercury in brain, blood, and urine are shown to be consistent with low absorbed doses (1-3 micrograms/day). Published relationships between the number of amalgam surfaces and urine levels are used to estimate the number of amalgam surfaces that would be required to produce the 30 micrograms/g creatinine urine mercury level stated by WHO to be associated with the most subtle, pre-clinical effects in the most sensitive individuals. From 450 to 530 amalgam surfaces would be required to produce the 30 micrograms/g creatinine urine mercury level for people without any excessive gum-chewing habits. The potential for adverse health effects and for improvement in health following amalgam removal is also addressed. Finally, the issue of whether any material can ever be completely exonerated of claims of producing adverse health effects is considered.

  10. Uncertainties in electron-absorbed fractions and lung doses from inhaled beta-emitters.

    PubMed

    Farfán, Eduardo B; Bolch, Wesley E; Huston, Thomas E; Rajon, Didier A; Huh, Chulhaeng; Bolch, W Emmett

    2005-01-01

    The computer code LUDUC (Lung Dose Uncertainty Code), developed at the University of Florida, was originally used to investigate the range of potential doses from the inhalation of either plutonium or uranium oxides. The code employs the ICRP Publication 66 Human Respiratory Tract model; however, rather than using simple point estimates for each of the model parameters associated with particle deposition, clearance, and lung-tissue dosimetry, probability density functions are ascribed to these parameters based upon detailed literature review. These distributions are subsequently sampled within LUDUC using Latin hypercube sampling techniques to generate multiple (e.g., approximately 1,000) sets of input vectors (i.e., trials), each yielding a unique estimate of lung dose. In the present study, the dosimetry component of the ICRP-66 model within LUDUC has been extended to explicitly consider variations in the beta particle absorbed fraction due to corresponding uncertainties and biological variabilities in both source and target tissue depths and thicknesses within the bronchi and bronchioles of the thoracic airways. Example dose distributions are given for the inhalation of absorption Type S compounds of 90Sr (Tmax = 546 keV) and 90Y (Tmax = 2,284 keV) as a function of particle size. Over the particle size range of 0.001 to 1 microm, estimates of total lung dose vary by a factor of 10 for 90Sr particles and by a factor of 4 to 10 for 90Y particles. As the particle size increases to 10 microm, dose uncertainties reach a factor of 100 for both radionuclides. In comparisons to identical exposures scenarios run by the LUDEP 2.0 code, Reference Man doses for inhaled beta-emitters were shown to provide slightly conservative estimates of lung dose compared to those in this study where uncertainties in lung airway histology are considered.

  11. Uncertainties in electron-absorbed fractions and lung doses from inhaled beta-emitters.

    PubMed

    Farfán, Eduardo B; Bolch, Wesley E; Huston, Thomas E; Rajon, Didier A; Huh, Chulhaeng; Bolch, W Emmett

    2005-01-01

    The computer code LUDUC (Lung Dose Uncertainty Code), developed at the University of Florida, was originally used to investigate the range of potential doses from the inhalation of either plutonium or uranium oxides. The code employs the ICRP Publication 66 Human Respiratory Tract model; however, rather than using simple point estimates for each of the model parameters associated with particle deposition, clearance, and lung-tissue dosimetry, probability density functions are ascribed to these parameters based upon detailed literature review. These distributions are subsequently sampled within LUDUC using Latin hypercube sampling techniques to generate multiple (e.g., approximately 1,000) sets of input vectors (i.e., trials), each yielding a unique estimate of lung dose. In the present study, the dosimetry component of the ICRP-66 model within LUDUC has been extended to explicitly consider variations in the beta particle absorbed fraction due to corresponding uncertainties and biological variabilities in both source and target tissue depths and thicknesses within the bronchi and bronchioles of the thoracic airways. Example dose distributions are given for the inhalation of absorption Type S compounds of 90Sr (Tmax = 546 keV) and 90Y (Tmax = 2,284 keV) as a function of particle size. Over the particle size range of 0.001 to 1 microm, estimates of total lung dose vary by a factor of 10 for 90Sr particles and by a factor of 4 to 10 for 90Y particles. As the particle size increases to 10 microm, dose uncertainties reach a factor of 100 for both radionuclides. In comparisons to identical exposures scenarios run by the LUDEP 2.0 code, Reference Man doses for inhaled beta-emitters were shown to provide slightly conservative estimates of lung dose compared to those in this study where uncertainties in lung airway histology are considered. PMID:15596988

  12. Theory, performance, and measured results with an improved absorbed dose water calorimeter. Final report

    SciTech Connect

    Domen, S.T.

    1982-01-01

    The feasibility of this calorimeter is mainly the result of the low thermal diffusivity of water that retards a temperature change at a point along a temperature profile. The temperature change is sensed by two calibrated thermistors sandwiched between two polyethylene films that electrically insulate the thermistors from water. The product of the temperature rise and the specific heat of water gives the combined effect of the absorbed dose and any heat defect. Temperature drifts are quickly controlled by making slight changes in electrical power dissipated in the water. Compared to solid-bodied calorimeters requiring vacuum systems, it was easy to construct, to get into operation, and to operate.

  13. Estimation of the absorbed dose in radiation-processed food. 4. EPR measurements on eggshell

    SciTech Connect

    Desrosiers, M.F.; Le, F.G. ); Harewood, P.M.; Josephson, E.S. ); Montesalvo, M. )

    1993-09-01

    Fresh whole eggs treated with ionizing radiation for Salmonellae control testing. The eggshell was then removed and examined by electron paramagnetic resonance (EPR) spectroscopy to determine if EPR could be used to (1) distinguish irradiated from unirradiated eggs and (2) assess the absorbed dose. No EPR signals were detected in unirradiated eggs, while strong signals were measurable for more than 200 days after irradiation. Although a number of EPR signals were measured, the most intense resonance (g = 2.0019) was used for dosimetry throughout the study. This signal was observed to increase linearly with dose (up to [approximately]6 kGy), which decayed [approximately]20% within the first 5 days after irradiation and remained relatively constant thereafter. The standard added-dose method was used to assess, retrospectively, the dose to eggs processed at 0.2, 0.7, and 1.4 kGy. Relatively good results were obtained when measurement was made on the day the shell was reirradiated; with this procedure estimates were better for shell processed at the lower doses.

  14. Radiobiologic risk estimation from dental radiology. Part I. Absorbed doses to critical organs

    SciTech Connect

    Underhill, T.E.; Chilvarquer, I.; Kimura, K.; Langlais, R.P.; McDavid, W.D.; Preece, J.W.; Barnwell, G.

    1988-07-01

    The aim of the present study was to generate one consistent set of data for evaluating and comparing radiobiologic risks from different dental radiographic techniques. To accomplish this goal, absorbed doses were measured in fourteen anatomic sites from (1) five different panoramic machines with the use of rare-earth screens, (2) a twenty-film complete-mouth survey with E-speed film, long round cone, (3) a twenty-film complete-mouth survey with E-speed film, long rectangular cone, (4) a four-film interproximal survey with E-speed film, long round cone, and (5) a four-film interproximal survey with E-speed film, long rectangular cone. The dose to the thyroid gland, the active bone marrow, the brain, and the salivary glands was evaluated by means of exposure of a tissue-equivalent phantom, fitted with lithium fluoride thermoluminescent dosimeters (TLDs) at the relevant locations.

  15. Radiation-induced biomarkers for the detection and assessment of absorbed radiation doses

    PubMed Central

    Rana, Sudha; Kumar, Raj; Sultana, Sarwat; Sharma, Rakesh Kumar

    2010-01-01

    Radiation incident involving living organisms is an uncommon but a very serious situation. The first step in medical management including triage is high-throughput assessment of the radiation dose received. Radiation exposure levels can be assessed from viability of cells, cellular organelles such as chromosome and different intermediate metabolites. Oxidative damages by ionizing radiation result in carcinogenesis, lowering of the immune response and, ultimately, damage to the hematopoietic system, gastrointestinal system and central nervous system. Biodosimetry is based on the measurement of the radiation-induced changes, which can correlate them with the absorbed dose. Radiation biomarkers such as chromosome aberration are most widely used. Serum enzymes such as serum amylase and diamine oxidase are the most promising biodosimeters. The level of gene expression and protein are also good biomarkers of radiation. PMID:21829314

  16. Radiobiologic risk estimation from dental radiology. Part I. Absorbed doses to critical organs.

    PubMed

    Underhill, T E; Chilvarquer, I; Kimura, K; Langlais, R P; McDavid, W D; Preece, J W; Barnwell, G

    1988-07-01

    The aim of the present study was to generate one consistent set of data for evaluating and comparing radiobiologic risks from different dental radiographic techniques. To accomplish this goal, absorbed doses were measured in fourteen anatomic sites from (1) five different panoramic machines with the use of rare-earth screens, (2) a twenty-film complete-mouth survey with E-speed film, long round cone, (3) a twenty-film complete-mouth survey with E-speed film, long rectangular cone, (4) a four-film interproximal survey with E-speed film, long round cone, and (5) a four-film interproximal survey with E-speed film, long rectangular cone. The dose to the thyroid gland, the active bone marrow, the brain, and the salivary glands was evaluated by means of exposure of a tissue-equivalent phantom, fitted with lithium fluoride thermoluminescent dosimeters (TLDs) at the relevant locations.

  17. Absorbed dose distribution visualization for superficial treatments through the Fricke Xylenol Gel dosimeter (FXG)

    NASA Astrophysics Data System (ADS)

    Alva, M.; Sampaio, F. G. A.; Moreira, M. V.; Petchevist, P. C. D.; de Almeida, A.

    2010-11-01

    Electrons, orthovoltage X-rays and betas are used for superficial treatments. It has been shown that it is practical to measure these three types of radiation using gel dosimetry, which is an accurate dosimetric tool, from which one can infer the absorbed dose. The Fricke Xylenol Gel (FXG) dosimeter has presented adequate results due to its spatial resolution, effective atomic number and density that are near to those of soft tissue. The aim of this work is to compare three types of radiation for skin treatments like orthovoltage (X-rays), brachytherapy (beta rays) and megavoltage (electrons) using the FXG-CCD dosimetric system to determine the calibration curves (CC), beam profiles (BP) and percentage depth dose curves (PDD), evidencing why for clinical applications a specific type of radiation is selected for superficial treatment. From the results obtained we can infer that the FXG-CCD system is adequate for linear, area and volume measurements.

  18. A Comparison of Model Calculation and Measurement of Absorbed Dose for Proton Irradiation. Chapter 5

    NASA Technical Reports Server (NTRS)

    Zapp, N.; Semones, E.; Saganti, P.; Cucinotta, F.

    2003-01-01

    With the increase in the amount of time spent EVA that is necessary to complete the construction and subsequent maintenance of ISS, it will become increasingly important for ground support personnel to accurately characterize the radiation exposures incurred by EVA crewmembers. Since exposure measurements cannot be taken within the organs of interest, it is necessary to estimate these exposures by calculation. To validate the methods and tools used to develop these estimates, it is necessary to model experiments performed in a controlled environment. This work is such an effort. A human phantom was outfitted with detector equipment and then placed in American EMU and Orlan-M EVA space suits. The suited phantom was irradiated at the LLUPTF with proton beams of known energies. Absorbed dose measurements were made by the spaceflight operational dosimetrist from JSC at multiple sites in the skin, eye, brain, stomach, and small intestine locations in the phantom. These exposures are then modeled using the BRYNTRN radiation transport code developed at the NASA Langley Research Center, and the CAM (computerized anatomical male) human geometry model of Billings and Yucker. Comparisons of absorbed dose calculations with measurements show excellent agreement. This suggests that there is reason to be confident in the ability of both the transport code and the human body model to estimate proton exposure in ground-based laboratory experiments.

  19. Thyroid absorbed dose for people at Rongelap, Utirik, and Sifo on March 1, 1954

    SciTech Connect

    Lessard, E.T.; Miltenberger, R.P.; Conrad, R.A.; Musoline, S.V.; Naidu, J.R.; Moorthy, A.; Schopfer, C.J.

    1985-03-01

    A study was undertaken to reexamine thyroid absorbed dose estimates for people accidentally exposed to fallout at Rongelap, Sifo, and Utirik Islands from the Pacific weapon test known as Operation Castle BRAVO. The study included: (1) reevaluation of radiochemical analysis, to relate results from pooled urine to intake, retention, and excretion functions; (2) analysis of neutron-irradiation studies of archival soil samples, to estimate areal activities of the iodine isotopes; (3) analysis of source term, weather data, and meteorological functions used in predicting atmospheric diffusion and fallout deposition, to estimate airborne concentrations of the iodine isotopes; and (4) reevaluation of radioactive fallout, which contaminated a Japanese fishing vessel in the vicinity of Rongelap Island on March 1, 1954, to determine fallout components. The conclusions of the acute exposure study were that the population mean thyroid absorbed doses were 21 gray (2100 rad) at Rongelap, 6.7 gray (670 rad) at Sifo, and 2.8 gray (280 rad) at Utirik. The overall thyroid cancer risk we estimated was in agreement with results published on the Japanese exposed at Nagasaki and Hiroshima. We now postulate that the major route for intake of fallout was by direct ingestion of food prepared and consumed outdoors. 66 refs., 13 figs., 25 tabs.

  20. ESR spectroscopy for detecting gamma-irradiated dried vegetables and estimating absorbed doses

    NASA Astrophysics Data System (ADS)

    Kwon, Joong-Ho; Chung, Hyung-Wook; Byun, Myung-Woo

    2000-03-01

    In view of an increasing demand for food irradiation technology, the development of a reliable means of detection for the control of irradiated foods has become necessary. Various vegetable food materials (dried cabbage, carrot, chunggyungchae, garlic, onion, and green onion), which can be legally irradiated in Korea, were subjected to a detection study using ESR spectroscopy. Correlation coefficients ( R2) between absorbed doses (2.5-15 kGy) and their corresponding ESR signals were identified from ESR signals. Pre-established threshold values were successfully applied to the detection of 54 coded unknown samples of dried clean vegetables ( chunggyungchae, Brassica camestris var. chinensis), both non-irradiated and irradiated. The ESR signals of irradiated chunggyungchae decreased over a longer storage time, however, even after 6 months of ambient storage, these signals were still distinguishable from those of non-irradiated samples. The most successful estimates of absorbed dose (5 and 8 kGy) were obtained immediately after irradiation using a quadratic fit with average values of 4.85 and 8.65 kGy being calculated.

  1. Fraction of a dose absorbed estimation for structurally diverse low solubility compounds.

    PubMed

    Sugano, Kiyohiko

    2011-02-28

    The purpose of the present study was to investigate the prediction accuracy of the fully mechanistic gastrointestinal unified theoretical (GUT) framework for in vivo oral absorption of low solubility drugs. Solubility in biorelevant media, molecular weight, logP(oct), pK(a), Caco-2 permeability, dose and particle size were used as the input parameters. To neglect the effect of the low stomach pH on dissolution of a drug, the fraction of a dose absorbed (Fa%) of undissociable and free acids were used. In addition, Fa% of free base drugs with the high pH stomach was also included to increase the number of model drugs. In total twenty nine structurally diverse compounds were used as the model drugs. Fa% data at several doses and particle sizes in humans and dogs were collated from the literature (total 110 Fa% data). In approximately 80% cases, the prediction error was within 2 fold, suggesting that the GUT framework has practical predictability for drug discovery, but not for drug development. The GUT framework appropriately captured the dose and particle size dependency of Fa% as the particle drifting effect was taken into account. It should be noted that the present validation results cannot be applied for salt form cases and other special formulations such as solid dispersions and emulsion formulations.

  2. Absolute calibration of the Gamma Knife{sup ®} Perfexion™ and delivered dose verification using EPR/alanine dosimetry

    SciTech Connect

    Hornbeck, Amaury E-mail: tristan.garcia@cea.fr; Garcia, Tristan E-mail: tristan.garcia@cea.fr; Cuttat, Marguerite; Jenny, Catherine

    2014-06-15

    Purpose: Elekta Leksell Gamma Knife{sup ®} (LGK) is a radiotherapy beam machine whose features are not compliant with the international calibration protocols for radiotherapy. In this scope, the Laboratoire National Henri Becquerel and the Pitié-Salpêtrière Hospital decided to conceive a new LKG dose calibration method and to compare it with the currently used one. Furthermore, the accuracy of the dose delivered by the LGK machine was checked using an “end-to-end” test. This study also aims to compare doses delivered by the two latest software versions of the Gammaplan treatment planning system (TPS). Methods: The dosimetric method chosen is the electron paramagnetic resonance (EPR) of alanine. Dose rate (calibration) verification was done without TPS using a spherical phantom. Absolute calibration was done with factors calculated by Monte Carlo simulation (MCNP-X). For “end-to-end” test, irradiations in an anthropomorphic head phantom, close to real treatment conditions, are done using the TPS in order to verify the delivered dose. Results: The comparison of the currently used calibration method with the new one revealed a deviation of +0.8% between the dose rates measured by ion chamber and EPR/alanine. For simple fields configuration (less than 16 mm diameter), the “end-to-end” tests showed out average deviations of −1.7% and −0.9% between the measured dose and the calculated dose by Gammaplan v9 and v10, respectively. Conclusions: This paper shows there is a good agreement between the new calibration method and the currently used one. There is also a good agreement between the calculated and delivered doses especially for Gammaplan v10.

  3. Absorbed dose-to-water protocol applied to synchrotron-generated x-rays at very high dose rates

    NASA Astrophysics Data System (ADS)

    Fournier, P.; Crosbie, J. C.; Cornelius, I.; Berkvens, P.; Donzelli, M.; Clavel, A. H.; Rosenfeld, A. B.; Petasecca, M.; Lerch, M. L. F.; Bräuer-Krisch, E.

    2016-07-01

    Microbeam radiation therapy (MRT) is a new radiation treatment modality in the pre-clinical stage of development at the ID17 Biomedical Beamline of the European synchrotron radiation facility (ESRF) in Grenoble, France. MRT exploits the dose volume effect that is made possible through the spatial fractionation of the high dose rate synchrotron-generated x-ray beam into an array of microbeams. As an important step towards the development of a dosimetry protocol for MRT, we have applied the International Atomic Energy Agency’s TRS 398 absorbed dose-to-water protocol to the synchrotron x-ray beam in the case of the broad beam irradiation geometry (i.e. prior to spatial fractionation into microbeams). The very high dose rates observed here mean the ion recombination correction factor, k s , is the most challenging to quantify of all the necessary corrections to apply for ionization chamber based absolute dosimetry. In the course of this study, we have developed a new method, the so called ‘current ramping’ method, to determine k s for the specific irradiation and filtering conditions typically utilized throughout the development of MRT. Using the new approach we deduced an ion recombination correction factor of 1.047 for the maximum ESRF storage ring current (200 mA) under typical beam spectral filtering conditions in MRT. MRT trials are currently underway with veterinary patients at the ESRF that require additional filtering, and we have estimated a correction factor of 1.025 for these filtration conditions for the same ESRF storage ring current. The protocol described herein provides reference dosimetry data for the associated Treatment Planning System utilized in the current veterinary trials and anticipated future human clinical trials.

  4. Absorbed dose-to-water protocol applied to synchrotron-generated x-rays at very high dose rates.

    PubMed

    Fournier, P; Crosbie, J C; Cornelius, I; Berkvens, P; Donzelli, M; Clavel, A H; Rosenfeld, A B; Petasecca, M; Lerch, M L F; Bräuer-Krisch, E

    2016-07-21

    Microbeam radiation therapy (MRT) is a new radiation treatment modality in the pre-clinical stage of development at the ID17 Biomedical Beamline of the European synchrotron radiation facility (ESRF) in Grenoble, France. MRT exploits the dose volume effect that is made possible through the spatial fractionation of the high dose rate synchrotron-generated x-ray beam into an array of microbeams. As an important step towards the development of a dosimetry protocol for MRT, we have applied the International Atomic Energy Agency's TRS 398 absorbed dose-to-water protocol to the synchrotron x-ray beam in the case of the broad beam irradiation geometry (i.e. prior to spatial fractionation into microbeams). The very high dose rates observed here mean the ion recombination correction factor, k s , is the most challenging to quantify of all the necessary corrections to apply for ionization chamber based absolute dosimetry. In the course of this study, we have developed a new method, the so called 'current ramping' method, to determine k s for the specific irradiation and filtering conditions typically utilized throughout the development of MRT. Using the new approach we deduced an ion recombination correction factor of 1.047 for the maximum ESRF storage ring current (200 mA) under typical beam spectral filtering conditions in MRT. MRT trials are currently underway with veterinary patients at the ESRF that require additional filtering, and we have estimated a correction factor of 1.025 for these filtration conditions for the same ESRF storage ring current. The protocol described herein provides reference dosimetry data for the associated Treatment Planning System utilized in the current veterinary trials and anticipated future human clinical trials. PMID:27366861

  5. An Absorbed-Dose/Dose-Rate Dependence for the Alanine-EPR Dosimetry System and Its Implications in High-Dose Ionizing Radiation Metrology

    PubMed Central

    Desrosiers, M. F.; Puhl, J. M.; Cooper, S. L.

    2008-01-01

    NIST developed the alanine dosimetry system in the early 1990s to replace radiochromic dye film dosimeters. Later in the decade the alanine system was firmly established as a transfer service for high-dose radiation dosimetry and an integral part of the internal calibration scheme supporting these services. Over the course of the last decade, routine monitoring of the system revealed a small but significant observation that, after examination, led to the characterization of a previously unknown absorbed-dose-dependent, dose-rate effect for the alanine system. Though the potential impact of this effect is anticipated to be extremely limited for NIST’s customer-based transfer dosimetry service, much greater implications may be realized for international measurement comparisons between National Measurement Institutes. PMID:27096113

  6. Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark.

    PubMed

    Renner, F; Wulff, J; Kapsch, R-P; Zink, K

    2015-10-01

    There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values. However, there is a lack of absolute benchmarks, i.e. benchmarks without involved normalization which may cause some quantities to be cancelled. Therefore, at the Physikalisch-Technische Bundesanstalt a benchmark experiment was performed, which aimed at the absolute verification of radiation transport calculations for dosimetry in radiation therapy. A thimble-type ionization chamber in a solid phantom was irradiated by high-energy bremsstrahlung and the mean absorbed dose in the sensitive volume was measured per incident electron of the target. The characteristics of the accelerator and experimental setup were precisely determined and the results of a corresponding Monte Carlo simulation with EGSnrc are presented within this study. For a meaningful comparison, an analysis of the uncertainty of the Monte Carlo simulation is necessary. In this study uncertainties with regard to the simulation geometry, the radiation source, transport options of the Monte Carlo code and specific interaction cross sections are investigated, applying the general methodology of the Guide to the expression of uncertainty in measurement. Besides studying the general influence of changes in transport options of the EGSnrc code, uncertainties are analyzed by estimating the sensitivity coefficients of various input quantities in a first step. Secondly, standard uncertainties are assigned to each quantity which are known from the experiment, e.g. uncertainties for geometric dimensions. Data for more fundamental quantities such as photon cross sections and the I-value of electron stopping powers are taken from literature. The significant uncertainty contributions are identified as

  7. Uncertainties in Monte Carlo-based absorbed dose calculations for an experimental benchmark.

    PubMed

    Renner, F; Wulff, J; Kapsch, R-P; Zink, K

    2015-10-01

    There is a need to verify the accuracy of general purpose Monte Carlo codes like EGSnrc, which are commonly employed for investigations of dosimetric problems in radiation therapy. A number of experimental benchmarks have been published to compare calculated values of absorbed dose to experimentally determined values. However, there is a lack of absolute benchmarks, i.e. benchmarks without involved normalization which may cause some quantities to be cancelled. Therefore, at the Physikalisch-Technische Bundesanstalt a benchmark experiment was performed, which aimed at the absolute verification of radiation transport calculations for dosimetry in radiation therapy. A thimble-type ionization chamber in a solid phantom was irradiated by high-energy bremsstrahlung and the mean absorbed dose in the sensitive volume was measured per incident electron of the target. The characteristics of the accelerator and experimental setup were precisely determined and the results of a corresponding Monte Carlo simulation with EGSnrc are presented within this study. For a meaningful comparison, an analysis of the uncertainty of the Monte Carlo simulation is necessary. In this study uncertainties with regard to the simulation geometry, the radiation source, transport options of the Monte Carlo code and specific interaction cross sections are investigated, applying the general methodology of the Guide to the expression of uncertainty in measurement. Besides studying the general influence of changes in transport options of the EGSnrc code, uncertainties are analyzed by estimating the sensitivity coefficients of various input quantities in a first step. Secondly, standard uncertainties are assigned to each quantity which are known from the experiment, e.g. uncertainties for geometric dimensions. Data for more fundamental quantities such as photon cross sections and the I-value of electron stopping powers are taken from literature. The significant uncertainty contributions are identified as

  8. A Feasibility Study of Fricke Dosimetry as an Absorbed Dose to Water Standard for 192Ir HDR Sources

    PubMed Central

    deAlmeida, Carlos Eduardo; Ochoa, Ricardo; de Lima, Marilene Coelho; David, Mariano Gazineu; Pires, Evandro Jesus; Peixoto, José Guilherme; Salata, Camila; Bernal, Mario Antônio

    2014-01-01

    High dose rate brachytherapy (HDR) using 192Ir sources is well accepted as an important treatment option and thus requires an accurate dosimetry standard. However, a dosimetry standard for the direct measurement of the absolute dose to water for this particular source type is currently not available. An improved standard for the absorbed dose to water based on Fricke dosimetry of HDR 192Ir brachytherapy sources is presented in this study. The main goal of this paper is to demonstrate the potential usefulness of the Fricke dosimetry technique for the standardization of the quantity absorbed dose to water for 192Ir sources. A molded, double-walled, spherical vessel for water containing the Fricke solution was constructed based on the Fricke system. The authors measured the absorbed dose to water and compared it with the doses calculated using the AAPM TG-43 report. The overall combined uncertainty associated with the measurements using Fricke dosimetry was 1.4% for k = 1, which is better than the uncertainties reported in previous studies. These results are promising; hence, the use of Fricke dosimetry to measure the absorbed dose to water as a standard for HDR 192Ir may be possible in the future. PMID:25521914

  9. A feasibility study of Fricke dosimetry as an absorbed dose to water standard for 192Ir HDR sources.

    PubMed

    deAlmeida, Carlos Eduardo; Ochoa, Ricardo; Lima, Marilene Coelho de; David, Mariano Gazineu; Pires, Evandro Jesus; Peixoto, José Guilherme; Salata, Camila; Bernal, Mario Antônio

    2014-01-01

    High dose rate brachytherapy (HDR) using 192Ir sources is well accepted as an important treatment option and thus requires an accurate dosimetry standard. However, a dosimetry standard for the direct measurement of the absolute dose to water for this particular source type is currently not available. An improved standard for the absorbed dose to water based on Fricke dosimetry of HDR 192Ir brachytherapy sources is presented in this study. The main goal of this paper is to demonstrate the potential usefulness of the Fricke dosimetry technique for the standardization of the quantity absorbed dose to water for 192Ir sources. A molded, double-walled, spherical vessel for water containing the Fricke solution was constructed based on the Fricke system. The authors measured the absorbed dose to water and compared it with the doses calculated using the AAPM TG-43 report. The overall combined uncertainty associated with the measurements using Fricke dosimetry was 1.4% for k = 1, which is better than the uncertainties reported in previous studies. These results are promising; hence, the use of Fricke dosimetry to measure the absorbed dose to water as a standard for HDR 192Ir may be possible in the future. PMID:25521914

  10. Late Effects After Radiotherapy for Locally Advanced Cervical Cancer: Comparison of Two Brachytherapy Schedules and Effect of Dose Delivered Weekly

    SciTech Connect

    Paulsen Hellebust, Taran; Kristensen, Gunnar B.; Olsen, Dag Rune

    2010-03-01

    Purpose: To compare the severe late effects (Grade 3 or greater) for two groups of cervical cancer patients treated with the same external beam radiotherapy and two high-dose-rate intracavitary brachytherapy regimens and to investigate the influence of the dose delivered each week. Methods and Materials: For 120 patients, intracavitary brachytherapy was delivered with 33.6 Gy in eight fractions to Point A (HD group), and for 119, intracavitary brachytherapy was delivered with 29.4 Gy in seven fractions to Point A (LD group). The cumulative incidence of severe gastrointestinal and genitourinary late effects were calculated for both dose groups using Kaplan-Meier survival analysis. This method was also used to explore whether the number of weeks with different dose levels could predict the cumulative incidence of late effects. Results: The actuarial rate of developing severe gastrointestinal morbidity at 7 years was 10.7% and 8.3% for HD and LD groups, respectively. The rate for genitourinary morbidity was 6.6% for the HD group and 5.0% for the LD group, respectively. No significant difference was found between the two groups. The analyses showed that a marginally significant increase occurred in severe gastrointestinal complications as the number of weeks with a physical dose >20 Gy increased in the HD group (p = .047). Conclusion: To establish dose-response relationships for late complications, three-dimensional imaging and dose-volume histogram parameters are needed. We found some indications that 20 Gy/wk is an upper tolerance level when the dose to the International Commission on Radiation Units and Measurements rectum point is 81 Gy{sub {alpha}/{beta}=3} (isoeffective [equivalent] dose of 2-Gy fractions). However, additional investigations using three-dimensional data are needed.

  11. Assessment of personnel absorbed dose at production of medical radioisotopes by a cyclotron.

    PubMed

    Sadat-Eshkevar, S M; Karimian, A; Mirzaee, M

    2011-09-01

    The medical radioisotope (201)Tl is produced by a cyclotron through the (203)Tl(p, 3n)(201)Pb reaction in the nuclear medicine research group of Agricultural, Medical and Industrial Research Schools in Iran. The produced (201)Pb decays to (201)Tl by electron capture. One of the most important problems that may occur is malfunction of a part of target or beam line, so that it needs the bombardment to be stopped and the problem fixed. In this work, induced radioactivity of the target, aluminium case of target, beam line and concrete walls of the thallium target room were calculated by Monte Carlo method. Then by using the results of the Monte Carlo simulation, the whole body absorbed dose to cyclotron personnel during repair and after stopping the bombardment, were assessed at different places of target room.

  12. Estimation of Organ Absorbed Doses in Patients from 99mTc-diphosphonate Using the Data of MIRDose Software

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Cheki, Mohsen; Moslehi, Masoud

    2012-01-01

    The purpose of this study was to compare estimation of radiation absorbed doses to patients following bone scans with technetium-99m-labeled methylene diphosphonate (MDP) with the estimates given in MIRDose software. In this study, each patient was injected 25 mCi of 99mTc-MDP. Whole-body images from thirty patients were acquired by gamma camera at 10, 60, 90, 180 minutes after 99mTc-MDP injection. To determine the amount of activity in each organ, conjugate view method was applied on images. MIRD equation was then used to estimate absorbed doses in different organs of patients. At the end, absorbed dose values obtained in this study were compared with the data of MIRDose software. The absorbed doses per unit of injected activity (mGy/MBq × 10–4) for liver, kidneys, bladder wall and spleen were 3.86 ± 1.1, 38.73 ± 4.7, 4.16 ± 1.8 and 3.91 ± 1.3, respectively. The results of this study may be useful to estimate the amount of activity that can be administered to the patient and also showed that methods used in the study for absorbed dose calculation is in good agreement with the data of MIRDose software and it is possible to use by a clinician. PMID:23724374

  13. Response functions for computing absorbed dose to skeletal tissues from neutron irradiation

    NASA Astrophysics Data System (ADS)

    Bahadori, Amir A.; Johnson, Perry; Jokisch, Derek W.; Eckerman, Keith F.; Bolch, Wesley E.

    2011-11-01

    Spongiosa in the adult human skeleton consists of three tissues—active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM50), defined as all tissues lying within the first 50 µm of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM50 targets in each bone of the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM50 and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM50 DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 Me

  14. Magnetic Resonance Imaging-Based Radiation-Absorbed Dose Estimation of {sup 166}Ho Microspheres in Liver Radioembolization

    SciTech Connect

    Seevinck, Peter R.; Maat, Gerrit H. van de; Wit, Tim C. de; Vente, Maarten A.D.; Nijsen, Johannes F.W.; Bakker, Chris J.G.

    2012-07-01

    Purpose: To investigate the potential of magnetic resonance imaging (MRI) for accurate assessment of the three-dimensional {sup 166}Ho activity distribution to estimate radiation-absorbed dose distributions in {sup 166}Ho-loaded poly (L-lactic acid) microsphere ({sup 166}Ho-PLLA-MS) liver radioembolization. Methods and Materials: MRI, computed tomography (CT), and single photon emission CT (SPECT) experiments were conducted on an anthropomorphic gel phantom with tumor-simulating gel samples and on an excised human tumor-bearing liver, both containing known amounts of {sup 166}Ho-PLLA-MS. Three-dimensional radiation-absorbed dose distributions were estimated at the voxel level by convolving the {sup 166}Ho activity distribution, derived from quantitative MRI data, with a {sup 166}Ho dose point-kernel generated by MCNP (Monte Carlo N-Particle transport code) and from Medical Internal Radiation Dose Pamphlet 17. MRI-based radiation-absorbed dose distributions were qualitatively compared with CT and autoradiography images and quantitatively compared with SPECT-based dose distributions. Both MRI- and SPECT-based activity estimations were validated against dose calibrator measurements. Results: Evaluation on an anthropomorphic phantom showed that MRI enables accurate assessment of local {sup 166}Ho-PLLA-MS mass and activity distributions, as supported by a regression coefficient of 1.05 and a correlation coefficient of 0.99, relating local MRI-based mass and activity calculations to reference values obtained with a dose calibrator. Estimated MRI-based radiation-absorbed dose distributions of {sup 166}Ho-PLLA-MS in an ex vivo human liver visually showed high correspondence to SPECT-based radiation-absorbed dose distributions. Quantitative analysis revealed that the differences in local and total amounts of {sup 166}Ho-PLLA-MS estimated by MRI, SPECT, and the dose calibrator were within 10%. Excellent agreement was observed between MRI- and SPECT-based dose

  15. Measurement of effects of nasal and facial shields on delivered radiation dose for superficial x-ray treatments

    NASA Astrophysics Data System (ADS)

    Yu, Peter K. N.; Butson, Martin J.

    2013-03-01

    Kilovoltage x-ray beams are used for the treatment of facial cancers when located on the patient's skin or subcutaneous tissue. This is of course due to the sharp depth dose characteristics of these beams delivering much lower doses at depth, than high energy x-ray beams. When treatment is performed, lead shields are often used within the nasal passage, or behind the lips and ears. These shields affect the backscattering patterns of the x-ray beams producing perturbations to upstream dose thus reducing delivered dose to the tumour. Experimental results using radiochromic films have shown that up to 10.5% ± 1.9% reduction in tumour dose can occur for field sizes less than 5 cm circle diameter for x-ray beams of 50 to 150 kVp. These results were confirmed using EGSnrc Monte Carlo techniques. Clinically more than 70% of treatments used fields of diameters less than 3 cm where the reductions were up to 6% ± 1.3%. Using a 1 cm diameter field, which can be used for skin cancer treatment on the nose, reductions up to 2.5% ± 1.3% were seen. Thus corrections need to be applied for dose calculations when underlying lead shields are used clinically in kilovoltage x-rays. The size of the reduction was also found to be dependent on the depth of the shield which will normally clinically vary from approximately 0.5 cm for nasal shields or behind eye lobes and up to approximately 1 cm for lips or cheek areas. We recommend that clinics utilize data for corrections to delivered dose in kilovoltage x-ray beams when lead shields are used in nasal passages, behind lips or behind ears for dose reduction. This can be easily and accurately measured with EBT2 Gafchromic film.

  16. Monte Carlo Analysis of Pion Contribution to Absorbed Dose from Galactic Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Aghara, S.K.; Battnig, S.R.; Norbury, J.W.; Singleterry, R.C.

    2009-01-01

    Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV - GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

  17. Monte Carlo analysis of pion contribution to absorbed dose from Galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Aghara, S. K.; Blattnig, S. R.; Norbury, J. W.; Singleterry, R. C.

    2009-04-01

    Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV-GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

  18. Study of natural radionuclide and absorbed gamma dose in Ukhimath area of Garhwal Himalaya, India.

    PubMed

    Rautela, B S; Yadav, M; Bourai, A A; Joshi, V; Gusain, G S; Ramola, R C

    2012-11-01

    Natural radiation is the largest contributor to the collective radiation dose of the world population. It is widely distributed in different geological formations such as soil, rocks, air and groundwater. In the present investigation, (226)Ra, (232)Th and (40)K were measured in soil samples of the Ukhimath region of Garhwal Himalaya, India using NaI(Tl) gamma-ray spectrometry. The activity concentrations of naturally occurring radionuclides (226)Ra, (232)Th and (40)K were found to vary from 38.4 ± 6.1 to 141.7 ± 11.9 Bq kg(-1) with an average of 80.5 Bq kg(-1), 57.0 ± 7.5 to 155.9 ± 12.4 Bq kg(-1) with an average of 118.9 Bq kg(-1) and 9.0 ± 3.0 to 672.8 ± 25.9 Bq kg(-1) with an average of 341 Bq kg(-1), respectively. The total absorbed gamma dose rate varies from 70.4 to 169.1 nGy h(-1) with an average of 123.4 nGy h(-1). This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details.

  19. Dependence of TLD thermoluminescence yield on absorbed dose in a thermal neutron field.

    PubMed

    Gambarini, G; Roy, M S

    1997-01-01

    The emission from 6LiF and 7LiF thermoluminescence dosimeters (TLDs) exposed to the mixed field of thermal neutrons and gamma-rays of the thermal facility of a TRIGA MARK II nuclear reactor has been investigated for various thermal neutron fluences of the order of magnitude of those utilised in radiotherapy, with the purpose of investigating the reliability of TLD readouts in such radiation fields and of giving some information for better obtainment of the absorbed dose values. The emission after exposure in this mixed field is compared with the emission after gamma-rays only. The glow curves have been deconvoluted into gaussian peaks, and the differences in the characteristics of the peaks observed for the two radiation fields, having different linear energy transfers, and for different doses are shown. Irreversible radiation damage in dosimeters having high sensitivity to thermal neutrons is also reported, showing a memory effect of the previous thermal neutron irradiation history which is not restored by anneal treatment. PMID:9463872

  20. A simplified technique for delivering total body irradiation (TBI) with improved dose homogeneity

    SciTech Connect

    Yao Rui; Bernard, Damian; Turian, Julius; Abrams, Ross A.; Sensakovic, William; Fung, Henry C.; Chu, James C. H.

    2012-04-15

    Purpose: Total body irradiation (TBI) with megavoltage photon beams has been accepted as an important component of management for a number of hematologic malignancies, generally as part of bone marrow conditioning regimens. The purpose of this paper is to present and discuss the authors' TBI technique, which both simplifies the treatment process and improves the treatment quality. Methods: An AP/PA TBI treatment technique to produce uniform dose distributions using sequential collimator reductions during each fraction was implemented, and a sample calculation worksheet is presented. Using this methodology, the dosimetric characteristics of both 6 and 18 MV photon beams, including lung dose under cerrobend blocks was investigated. A method of estimating midplane lung doses based on measured entrance and exit doses was proposed, and the estimated results were compared with measurements. Results: Whole body midplane dose uniformity of {+-}10% was achieved with no more than two collimator-based beam modulations. The proposed model predicted midplane lung doses 5% to 10% higher than the measured doses for 6 and 18 MV beams. The estimated total midplane doses were within {+-}5% of the prescribed midplane dose on average except for the lungs where the doses were 6% to 10% lower than the prescribed dose on average. Conclusions: The proposed TBI technique can achieve dose uniformity within {+-}10%. This technique is easy to implement and does not require complicated dosimetry and/or compensators.

  1. Analysis of the Body Distribution of Absorbed Dose in the Organs of Three Species of Fish from Sepetiba Bay

    SciTech Connect

    Pereira, Wagner de S; Kelecom, Alphonse; Santos Gouvea, Rita de Cassia dos; Azevedo Py Junior, Delcy de

    2008-08-07

    The body distribution of Polonium-210 in three fishes from the Sepetiba Bay (Macrodon ancylodon, Micropogonias furnieri and Mugil curema) has been studied under the approach of the Department of Energy of the United States of America (DOE) that set the limit of absorbed dose rate in biota equal to 3.5x10{sup 3} {mu}Gy/y, and that also established the relation between dose rate (D) and radionuclide concentration (c) on a fish muscle fresh weight basis, as follows: D = 5.05 ExNxC, assuming that the radionuclide distribution is homogenous among organs. Two hypotheses were tested here, using statistical tools: 1) is the body distribution of absorbed dose homogenous among organs? and 2) is the body distribution of absorbed dose identical among studied fishes? It was concluded, as expected, that the distribution among organs is heterogeneous; but, unexpectedly, that the three fishes display identical body distribution pattern, although they belong to different trophic levels. Hence, concerning absorbed dose calculation, the statement that data distribution is homogenous must be understood merely as an approximation, at least in the case of Polonium-210.

  2. Computational Modeling of Cellular Effects Post-Irradiation with Low- and High-Let Particles and Different Absorbed Doses

    PubMed Central

    Tavares, Adriana Alexandre S.; Tavares, João Manuel R. S.

    2013-01-01

    The use of computational methods to improve the understanding of biological responses to various types of radiation is an approach where multiple parameters can be modelled and a variety of data is generated. This study compares cellular effects modelled for low absorbed doses against high absorbed doses. The authors hypothesized that low and high absorbed doses would contribute to cell killing via different mechanisms, potentially impacting on targeted tumour radiotherapy outcomes. Cellular kinetics following irradiation with selective low- and high-linear energy transfer (LET) particles were investigated using the Virtual Cell (VC) radiobiology algorithm. Two different cell types were assessed using the VC radiobiology algorithm: human fibroblasts and human crypt cells. The results showed that at lower doses (0.01 to 0.2 Gy), all radiation sources used were equally able to induce cell death (p>0.05, ANOVA). On the other hand, at higher doses (1.0 to 8.0 Gy), the radiation response was LET and dose dependent (p<0.05, ANOVA). The data obtained suggests that the computational methods used might provide some insight into the cellular effects following irradiation. The results also suggest that it may be necessary to re-evaluate cellular radiation-induced effects, particularly at low doses that could affect therapeutic effectiveness. PMID:23930101

  3. Transcriptional Response in Mouse Thyroid Tissue after 211At Administration: Effects of Absorbed Dose, Initial Dose-Rate and Time after Administration

    PubMed Central

    Rudqvist, Nils; Spetz, Johan; Schüler, Emil; Parris, Toshima Z.; Langen, Britta; Helou, Khalil; Forssell-Aronsson, Eva

    2015-01-01

    Background 211At-labeled radiopharmaceuticals are potentially useful for tumor therapy. However, a limitation has been the preferential accumulation of released 211At in the thyroid gland, which is a critical organ for such therapy. The aim of this study was to determine the effect of absorbed dose, dose-rate, and time after 211At exposure on genome-wide transcriptional expression in mouse thyroid gland. Methods BALB/c mice were i.v. injected with 1.7, 7.5 or 100 kBq 211At. Animals injected with 1.7 kBq were killed after 1, 6, or 168 h with mean thyroid absorbed doses of 0.023, 0.32, and 1.8 Gy, respectively. Animals injected with 7.5 and 100 kBq were killed after 6 and 1 h, respectively; mean thyroid absorbed dose was 1.4 Gy. Total RNA was extracted from pooled thyroids and the Illumina RNA microarray platform was used to determine mRNA levels. Differentially expressed transcripts and enriched GO terms were determined with adjusted p-value <0.01 and fold change >1.5, and p-value <0.05, respectively. Results In total, 1232 differentially expressed transcripts were detected after 211At administration, demonstrating a profound effect on gene regulation. The number of regulated transcripts increased with higher initial dose-rate/absorbed dose at 1 or 6 h. However, the number of regulated transcripts decreased with mean absorbed dose/time after 1.7 kBq 211At administration. Furthermore, similar regulation profiles were seen for groups administered 1.7 kBq. Interestingly, few previously proposed radiation responsive genes were detected in the present study. Regulation of immunological processes were prevalent at 1, 6, and 168 h after 1.7 kBq administration (0.023, 0.32, 1.8 Gy). PMID:26177204

  4. Parotid Glands Dose–Effect Relationships Based on Their Actually Delivered Doses: Implications for Adaptive Replanning in Radiation Therapy of Head-and-Neck Cancer

    SciTech Connect

    Hunter, Klaudia U.; Fernandes, Laura L.; Vineberg, Karen A.; McShan, Daniel; Antonuk, Alan E.; Cornwall, Craig; Feng, Mary; Schipper, Mathew J.; Balter, James M.; Eisbruch, Avraham

    2013-11-15

    Purpose: Doses actually delivered to the parotid glands during radiation therapy often exceed planned doses. We hypothesized that the delivered doses correlate better with parotid salivary output than the planned doses, used in all previous studies, and that determining these correlations will help make decisions regarding adaptive radiation therapy (ART) aimed at reducing the delivered doses. Methods and Materials: In this prospective study, oropharyngeal cancer patients treated definitively with chemoirradiation underwent daily cone-beam computed tomography (CBCT) with clinical setup alignment based on the C2 posterior edge. Parotid glands in the CBCTs were aligned by deformable registration to calculate cumulative delivered doses. Stimulated salivary flow rates were measured separately from each parotid gland pretherapy and periodically posttherapy. Results: Thirty-six parotid glands of 18 patients were analyzed. Average mean planned doses was 32 Gy, and differences from planned to delivered mean gland doses were −4.9 to +8.4 Gy, median difference +2.2 Gy in glands in which delivered doses increased relative to planned. Both planned and delivered mean doses were significantly correlated with posttreatment salivary outputs at almost all posttherapy time points, without statistically significant differences in the correlations. Large dispersions (on average, SD 3.6 Gy) characterized the dose–effect relationships for both. The differences between the cumulative delivered doses and planned doses were evident at first fraction (r=.92, P<.0001) because of complex setup deviations (eg, rotations and neck articulations), uncorrected by the translational clinical alignments. Conclusions: After daily translational setup corrections, differences between planned and delivered doses in most glands were small relative to the SDs of the dose–saliva data, suggesting that ART is not likely to gain measurable salivary output improvement in most cases. These differences were

  5. Proton and photon absorbed-dose conversion coefficients for embryo and foetus from top-down irradiation geometry.

    PubMed

    Chen, Jing

    2007-01-01

    Absorbed-dose conversion coefficients are calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months when the mother's body is exposed to protons and photons from top-down (TOP) direction. It provides data sets in addition to other standard irradiation geometries published previously. The TOP-irradiation geometry is considered here, because high-energy particles are often peaked from the TOP direction onboard aircrafts. The results show that absorbed-doses from high-energy particles could be underestimated significantly if isotropic (ISO) irradiation geometry is assumed. For protons of 100 GeV, absorbed-doses from TOP irradiation are approximately 2.3-2.9 times higher than the doses from ISO irradiation for different foetal ages. For 10 GeV photons, foetal doses from TOP irradiation are approximately 6.8-12 times higher than the doses from ISO irradiation. The coefficients from TOP-irradiation geometry are given in wide energy ranges, from 100 MeV to 100 GeV for protons and from 50 keV to 10 GeV for photons. They can, therefore, be used in various applications whenever exposure from the TOP-irradiation direction is concerned.

  6. Assessment of absorbed dose to thyroid, parotid and ovaries in patients undergoing Gamma Knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Hasanzadeh, H.; Sharafi, A.; Allah Verdi, M.; Nikoofar, A.

    2006-09-01

    Stereotactic radiosurgery was originally introduced by Lars Leksell in 1951. This treatment refers to the noninvasive destruction of an intracranial target localized stereotactically. The purpose of this study was to identify the dose delivered to the parotid, ovaries, testis and thyroid glands during the Gamma Knife radiosurgery procedure. A three-dimensional, anthropomorphic phantom was developed using natural human bone, paraffin and sodium chloride as the equivalent tissue. The phantom consisted of a thorax, head and neck and hip. In the natural places of the thyroid, parotid (bilateral sides) and ovaries (midline), some cavities were made to place TLDs. Three TLDs were inserted in a batch with 1 cm space between the TLDs and each batch was inserted into a single cavity. The final depth of TLDs was 3 cm from the surface for parotid and thyroid and was 15 cm for the ovaries. Similar batches were placed superficially on the phantom. The phantom was gamma irradiated using a Leksell model C Gamma Knife unit. Subsequently, the same batches were placed superficially over the thyroid, parotid, testis and ovaries in 30 patients (15 men and 15 women) who were undergoing radiosurgery treatment for brain tumours. The mean dosage for treating these patients was 14.48 ± 3.06 Gy (10.5-24 Gy) to a mean tumour volume of 12.30 ± 9.66 cc (0.27-42.4 cc) in the 50% isodose curve. There was no significant difference between the superficial and deep batches in the phantom studies (P-value < 0.05). The mean delivered doses to the parotid, thyroid, ovaries and testis in human subjects were 21.6 ± 15.1 cGy, 9.15 ± 3.89 cGy, 0.47 ± 0.3 cGy and 0.53 ± 0.31 cGy, respectively. The data can be used in making decisions for special clinical situations such as treating pregnant patients or young patients with benign lesions who need radiosurgery for eradication of brain tumours.

  7. Visible photoluminescence of color centers in LiF crystals for absorbed dose evaluation in clinical dosimetry

    NASA Astrophysics Data System (ADS)

    Villarreal-Barajas, J. E.; Piccinini, M.; Vincenti, M. A.; Bonfigli, F.; Khan, R. F.; Montereali, R. M.

    2015-04-01

    Among insulating materials, lithium fluoride (LiF) has been successfully used as ionizing radiation dosemeter for more than 60 years. Thermoluminescence (TL) has been the most commonly used reading technique to evaluate the absorbed dose. Lately, optically stimulated luminescence (OSL) of visible emitting color centers (CCs) has also been explored in pure and doped LiF. This work focuses on the experimental behaviour of nominally pure LiF crystals dosemeters for 6 MV x rays at low doses based on photoluminescence (PL) of radiation induced CCs. Polished LiF crystals were irradiated using 6 MV x rays produced by a clinical linear accelerator. The doses (absorbed dose to water) covered the 1-100 Gy range. Optical absorption spectra show stable formation of primary F defects up to a maximum concentration of 2×1016 cm-3, while no significant M absorption band at around 450 nm was detected. On the other hand, under Argon laser excitation at 458 nm, PL spectra of the irradiated LiF crystals clearly exhibited the characteristic F2 and F+3 visible broad emission bands. Their sum intensity is linearly proportional to the absorbed dose in the investigated range. PL integrated intensity was also measured using a conventional fluorescence optical microscope under blue lamp illumination. The relationship between the absorbed dose and the integrated F2 and F+3 PL intensities, represented by the net average pixel number in the optical fluorescence images, is also fairly linear. Even at the low point defect densities obtained at the investigated doses, these preliminary experimental results are encouraging for further investigation of CCs PL in LiF crystals for clinical dosimetry.

  8. In vivo verification of radiation dose delivered to healthy tissue during radiotherapy for breast cancer

    NASA Astrophysics Data System (ADS)

    Lonski, P.; Taylor, M. L.; Hackworth, W.; Phipps, A.; Franich, R. D.; Kron, T.

    2014-03-01

    Different treatment planning system (TPS) algorithms calculate radiation dose in different ways. This work compares measurements made in vivo to the dose calculated at out-of-field locations using three different commercially available algorithms in the Eclipse treatment planning system. LiF: Mg, Cu, P thermoluminescent dosimeter (TLD) chips were placed with 1 cm build-up at six locations on the contralateral side of 5 patients undergoing radiotherapy for breast cancer. TLD readings were compared to calculations of Pencil Beam Convolution (PBC), Anisotropic Analytical Algorithm (AAA) and Acuros XB (XB). AAA predicted zero dose at points beyond 16 cm from the field edge. In the same region PBC returned an unrealistically constant result independent of distance and XB showed good agreement to measured data although consistently underestimated by ~0.1 % of the prescription dose. At points closer to the field edge XB was the superior algorithm, exhibiting agreement with TLD results to within 15 % of measured dose. Both AAA and PBC showed mixed agreement, with overall discrepancies considerably greater than XB. While XB is certainly the preferable algorithm, it should be noted that TPS algorithms in general are not designed to calculate dose at peripheral locations and calculation results in such regions should be treated with caution.

  9. An estimate by two methods of thyroid absorbed doses due to BRAVO fallout in several northern Marshall Islands

    SciTech Connect

    Musolino, S.V.; Hull, A.P.; Greenhouse, N.A.

    1997-10-01

    Estimates of the thyroid absorbed doses due to fallout originating from the 1 March 1954 BRAVO thermonuclear test on Bikini Atoll have been made for several inhabited locations in the Northern Marshall Islands. Rongelap, Utirik, Rongerik and Ailinginae Atolls were also inhabited on 1 March 1954, where retrospective thyroid absorbed doses have previously been reconstructed. Current estimates are based primarily on external exposure data, which were recorded shortly after each nuclear test in the Castle Series, and secondarily on soil concentrations of {sup 137}Cs in samples collected in 1978 and 1988, along with aerial monitoring done in 1978. External exposures and {sup 137}Cs Soil concentrations were representative of the atmospheric transport and deposition patterns of the entire Castle Series tests and show that the BRAVO test was the major contributor to fallout exposure during the Castle series and other test series which were carried out in the Marshall Islands. These data have been used as surrogates for fission product radioiodines and telluriums in order to estimate the range of thyroid absorbed doses that may have occurred throughout the Marshall Islands. Dosimetry based on these two sets of estimates agreed within a factor of 4 at the locations where BRAVO was the dominant contributor to the total exposure and deposition. Both methods indicate that thyroid absorbed doses in the range of 1 Gy (100 rad) may have been incurred in some of the northern locations, whereas the doses at southern locations did not significantly exceed levels comparable to those from worldwide fallout. The results of these estimates indicate that a systematic medical survey for thyroid disease should be conducted, and that a more definitive dose reconstruction should be made for all the populated atolls and islands in the Northern Marshall Islands beyond Rongelap, Utirik, Rongerik and Ailinginae, which were significantly contaminated by BRAVO fallout. 30 refs., 2 figs., 10 tabs.

  10. Determination of the Absorbed Dose Rate to Water for the 18-mm Helmet of a Gamma Knife

    SciTech Connect

    Chung, Hyun-Tai; Park, Youngho; Hyun, Sangil; Choi, Yongsoo; Kim, Gi Hong; Kim, Dong Gyu; Chun, Kook Jin

    2011-04-01

    Purpose: To measure the absorbed dose rate to water of {sup 60}Co gamma rays of a Gamma Knife Model C using water-filled phantoms (WFP). Methods and Materials: Spherical WFP with an equivalent water depth of 5, 7, 8, and 9 cm were constructed. The dose rates at the center of an 18-mm helmet were measured in an 8-cm WFP (WFP-3) and two plastic phantoms. Two independent measurement systems were used: one was calibrated to an air kerma (Set I) and the other was calibrated to the absorbed dose to water (Set II). The dose rates of WFP-3 and the plastic phantoms were converted to dose rates for an 8-cm water depth using the attenuation coefficient and the equivalent water depths. Results: The dose rate measured at the center of WFP-3 using Set II was 2.2% and 1.0% higher than dose rates measured at the center of the two plastic phantoms. The measured effective attenuation coefficient of Gamma Knife photon beam in WFPs was 0.0621 cm{sup -1}. After attenuation correction, the difference between the dose rate at an 8-cm water depth measured in WFP-3 and dose rates in the plastic phantoms was smaller than the uncertainty of the measurements. Conclusions: Systematic errors related to the characteristics of the phantom materials in the dose rate measurement of a Gamma Knife need to be corrected for. Correction of the dose rate using an equivalent water depth and attenuation provided results that were more consistent.

  11. 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.

  12. Absorbed dose measurements for kV-cone beam computed tomography in image-guided radiation therapy

    NASA Astrophysics Data System (ADS)

    Hioki, Kazunari; Araki, Fujio; Ohno, Takeshi; Nakaguchi, Yuji; Tomiyama, Yuuki

    2014-12-01

    In this study, we develope a novel method to directly evaluate an absorbed dose-to-water for kilovoltage-cone beam computed tomography (kV-CBCT) in image-guided radiation therapy (IGRT). Absorbed doses for the kV-CBCT systems of the Varian On-Board Imager (OBI) and the Elekta X-ray Volumetric Imager (XVI) were measured by a Farmer ionization chamber with a 60Co calibration factor. The chamber measurements were performed at the center and four peripheral points in body-type (30 cm diameter and 51 cm length) and head-type (16 cm diameter and 33 cm length) cylindrical water phantoms. The measured ionization was converted to the absorbed dose-to-water by using a 60Co calibration factor and a Monte Carlo (MC)-calculated beam quality conversion factor, kQ, for 60Co to kV-CBCT. The irradiation for OBI and XVI was performed with pelvis and head modes for the body- and the head-type phantoms, respectively. In addition, the dose distributions in the phantom for both kV-CBCT systems were calculated with MC method and were compared with measured values. The MC-calculated doses were calibrated at the center in the water phantom and compared with measured doses at four peripheral points. The measured absorbed doses at the center in the body-type phantom were 1.96 cGy for OBI and 0.83 cGy for XVI. The peripheral doses were 2.36-2.90 cGy for OBI and 0.83-1.06 cGy for XVI. The doses for XVI were lower up to approximately one-third of those for OBI. Similarly, the measured doses at the center in the head-type phantom were 0.48 cGy for OBI and 0.21 cGy for XVI. The peripheral doses were 0.26-0.66 cGy for OBI and 0.16-0.30 cGy for XVI. The calculated peripheral doses agreed within 3% in the pelvis mode and within 4% in the head mode with measured doses for both kV-CBCT systems. In addition, the absorbed dose determined in this study was approximately 4% lower than that in TG-61 but the absorbed dose by both methods was in agreement within their combined

  13. Influence of lead apron shielding on absorbed doses from panoramic radiography

    PubMed Central

    Rottke, D; Grossekettler, L; Sawada, K; Poxleitner, P; Schulze, D

    2013-01-01

    Objectives: This study investigated the absorbed doses in a full anthropomorphic body phantom from two different panoramic radiography devices, performing protocols with and without applying a lead apron. Methods: A RANDO® full body phantom (Alderson Research Laboratories Inc., Stamford, CT) was equipped with 110 thermoluminescent dosemeters at 55 different sites and set up in two different panoramic radiography devices [SCANORA® three-dimensional (3D) (SOREDEX, Tuusula, Finland) and ProMax® 3D (Planmeca, Helsinki, Finland)] and exposed. Two different protocols were performed in the two devices. The first protocol was performed without any lead shielding, whereas the phantom was equipped with a standard adult lead apron for the second protocol. Results: A two-tailed paired samples t-test for the SCANORA 3D revealed that there is no difference between the protocol using lead apron shielding (m = 87.99, s = 102.98) and the protocol without shielding (m = 87.34, s = 107.49), t(54) = −0.313, p > 0.05. The same test for the ProMax 3D showed that there is also no difference between the protocol using shielding (m = 106.48, s = 117.38) and the protocol without shielding (m = 107.75, s = 114,36), t(54) = 0.938, p > 0.05. Conclusions: In conclusion, the results of this study showed no statistically significant differences between a panoramic radiography with or without the use of lead apron shielding. PMID:24174012

  14. Radiation absorbed dose estimates for oxygen-15 radiopharmaceuticals (H2( V)O, C VO, O VO) in newborn infants

    SciTech Connect

    Powers, W.J.; Stabin, M.; Howse, D.; Eichling, J.O.; Herscovitch, P.

    1988-12-01

    In preparation for measurement of regional cerebral oxygen metabolism by positron emission tomography, radiation absorbed dose estimates for 19 internal organs, blood, and total body were calculated for newborn infants following bolus intravenous administration of H2( V)O and brief inhalation of C VO and O VO. Cumulated activity for each radiopharmaceutical was calculated from a compartmental model based on the known biologic behavior of the compound. Values for mean absorbed dose/unit cumulated activity (S) for internal organs and total body were based on a newborn phantom. S was separately calculated for blood. Total radiopharmaceutical absorbed dose estimates necessary to measure cerebral oxygen metabolism in a 3.51-kg infant based on 0.7 mCi/kg H2( V)O and 1 mCi/kg C VO and O VO were determined to be 1.6 rad to the lung (maximum organ dose), 0.28 rad to the marrow, 0.46 rad to the gonads, and 0.22 rad to total body. These values are similar to those for current clinical nuclear medicine procedures employing /sup 99m/Tc in newborn infants.

  15. The PTB primary standard for the absorbed-dose to water for I-125 interstitial brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Schneider, T.

    2012-10-01

    The German national metrology institute (PTB) developed a primary standard in terms of absorbed-dose to water Dw for low-energy interstitial brachytherapy sources, which is based on an extrapolation chamber in a phantom of water-equivalent material. The method to determine Dw from extrapolation chamber measurements has been newly developed and is already described in the literature. With the chamber the absorbed-dose at 30 cm distance from the source is measured and the quantity is converted into the desired quantity, the absorbed-dose to water measured at 1 cm distance perpendicular to the source axis. In this paper, a synthesis of the work done within the EMRP Project: ‘TP2.JRP6: Increasing Cancer Treatment Efficacy Using 3D Brachytherapy’ is given and the final results and the final uncertainty budget are presented. Furthermore, an experimentally determined dose-rate constant for this seed type (BEBIG Symmetra I25.S16) is given based on the measurement of four different instances.

  16. SU-E-J-176: Characterization of Inter-Fraction Breast Variability and the Implications On Delivered Dose

    SciTech Connect

    Sudhoff, M; Lamba, M; Kumar, N; Ward, A; Elson, H

    2015-06-15

    Purpose: To systematically characterize inter-fraction breast variability and determine implications on delivered dose. Methods: Weekly port films were used to characterize breast setup variability. Five evenly spaced representative positions across the contour of each breast were chosen on the electronic port film in reference to graticule, and window and level was set such that the skin surface of the breast was visible. Measurements from the skin surface to treatment field edge were taken on each port film at each position and compared to the planning DRR, quantifying the variability. The systematic measurement technique was repeated for all port films for 20 recently treated breast cancer patients. Measured setup variability for each patient was modeled as a normal distribution. The distribution was randomly sampled from the model and applied as isocentric shifts in the treatment planning computer, representing setup variability for each fraction. Dose was calculated for each shifted fraction and summed to obtain DVHs and BEDs that modeled the dose with daily setup variability. Patients were categorized in to relevant groupings that were chosen to investigate the rigorousness of immobilization types, treatment techniques, and inherent anatomical difficulties. Mean position differences and dosimetric differences were evaluated between planned and delivered doses. Results: The setup variability was found to follow a normal distribution with mean position differences between the DRR and port film between − 8.6–3.5 mm with sigma range of 5.3–9.8 mm. Setup position was not found to be significantly different than zero. The mean seroma or whole breast PTV dosimetric difference, calculated as BED, ranged from a −0.23 to +1.13Gy. Conclusion: A systematic technique to quantify and model setup variability was used to calculate the dose in 20 breast cancer patients including variable setup. No statistically significant PTV or OAR BED differences were found between

  17. Development of a water calorimetry-based standard for absorbed dose to water in HDR {sup 192}Ir brachytherapy

    SciTech Connect

    Sarfehnia, Arman; Seuntjens, Jan

    2010-04-15

    Purpose: The aim of this article is to develop and evaluate a primary standard for HDR {sup 192}Ir brachytherapy based on 4 deg. C stagnant water calorimetry. Methods: The absolute absorbed dose to water was directly measured for several different Nucletron microSelectron {sup 192}Ir sources of air kerma strength ranging between 21 000 and 38 000 U and for source-to-detector separations ranging between 25 and 70 mm. The COMSOL MULTIPHYSICS software was used to accurately calculate the heat transport in a detailed model geometry. Through a coupling of the ''conduction and convection'' module with the ''Navier-Stokes incompressible fluid'' module in the software, both the conductive and convective effects were modeled. Results: A detailed uncertainty analysis resulted in an overall uncertainty in the absorbed dose of 1.90%(1{sigma}). However, this includes a 1.5% uncertainty associated with a nonlinear predrift correction which can be substantially reduced if sufficient time is provided for the system to come to a new equilibrium in between successive calorimetric runs, an opportunity not available to the authors in their clinical setting due to time constraints on the machine. An average normalized dose rate of 361{+-}7 {mu}Gy/(h U) at a source-to-detector separation of 55 mm was measured for the microSelectron {sup 192}Ir source based on water calorimetry. The measured absorbed dose per air kerma strength agreed to better than 0.8%(1{sigma}) with independent ionization chamber and EBT-1 Gafchromic film reference dosimetry as well as with the currently accepted AAPM TG-43 protocol measurements. Conclusions: This work paves the way toward a primary absorbed dose to water standard in {sup 192}Ir brachytherapy.

  18. Direct determination of the absorbed dose to water from 125I low dose-rate brachytherapy seeds using the new absorbed dose primary standard developed at ENEA-INMRI

    NASA Astrophysics Data System (ADS)

    Toni, M. P.; Pimpinella, M.; Pinto, M.; Quini, M.; Cappadozzi, G.; Silvestri, C.; Bottauscio, O.

    2012-10-01

    Low-intensity radioactive sources emitting low-energy photons are used in the clinic for low dose-rate brachytherapy treatments of tumours. The dosimetry of these sources is based on reference air kerma rate measurements. The absorbed dose rate to water at the reference depth d0 = 1 cm, \\dot {D}_{w,1\\,cm} , is then obtained by a conversion procedure with a large relative standard uncertainty of about 5%. This paper describes a primary standard developed at ENEA-INMRI to directly measure \\dot {D}_{w,1\\,cm} due to LDR sources. The standard is based on a large-angle and variable-volume ionization chamber, embedded in a graphite phantom and operating under ‘wall-less air chamber’ conditions. A set of correction and conversion factors, based on experiments and Monte Carlo simulations, are determined to obtain the value of Dw,1 cm from measurements of increment of ionization current with increasing chamber volume. The relative standard uncertainty on \\dot {D}_{w,1\\,cm} is 2.6%, which is appreciably lower than the current uncertainty. Characteristics of the standard, its associated uncertainty budget, and some experimental results are given for 125I BEBIG I25.S16.C brachytherapy seeds. Finally, results of the experimental determination of the dose-rate constant Λ1 cm, traceable to the Dw,1 cm and the low-energy air kerma ENEA-INMRI standards, are given. The relative standard uncertainty on Λ1 cm is 2.9%, appreciably lower than the typical uncertainty (4.8%) of the values available in the literature.

  19. Reduction of Dose Delivered to Organs at Risk in Prostate Cancer Patients via Image-Guided Radiation Therapy

    SciTech Connect

    Pawlowski, Jason M.; Yang, Eddy S.; Malcolm, Arnold W.; Coffey, Charles W.; Ding, George X.

    2010-03-01

    Purpose: To determine whether image guidance can improve the dose delivered to target organs and organs at risk (OARs) for prostate cancer patients treated with intensity-modulated radiotherapy (IMRT). Methods and Materials: Eight prostate cancer patients were treated with IMRT to 76 Gy at 2 Gy per fraction. Daily target localization was performed via alignment of three intraprostatic fiducials and weekly kV-cone beam computed tomography (CBCT) scans. The prostate and OARs were manually contoured on each CBCT by a single physician. Daily patient setup shifts were obtained by comparing alignment of skin tattoos with the treatment position based on fiducials. Treatment fields were retrospectively applied to CBCT scans. The dose distributions were calculated using actual treatment plans (an 8-mm PTV margin everywhere except for 6-mm posteriorly) with and without image guidance shifts. Furthermore, the feasibility of margin reduction was evaluated by reducing planning margins to 4 mm everywhere except for 3 mm posteriorly. Results: For the eight treatment plans on the 56 CBCT scans, the average doses to 98% of the prostate (D98) were 102% (range, 99-104%) and 99% (range, 45-104%) with and without image guidance, respectively. Using margin reduction, the average D98s were 100% (range, 84-104%) and 92% (range, 40-104%) with and without image guidance, respectively. Conclusions: Currently, margins used in IMRT plans are adequate to deliver a dose to the prostate with conventional patient positioning using skin tattoos or bony anatomy. The use of image guidance may facilitate significant reduction of planning margins. Future studies to assess the efficacy of decreasing margins and improvement of treatment-related toxicities are warranted.

  20. Design and implementation of a film dosimetry audit tool for comparison of planned and delivered dose distributions in high dose rate (HDR) brachytherapy.

    PubMed

    Palmer, Antony L; Lee, Chris; Ratcliffe, Ailsa J; Bradley, David; Nisbet, Andrew

    2013-10-01

    A novel phantom is presented for 'full system' dosimetric audit comparing planned and delivered dose distributions in HDR gynaecological brachytherapy, using clinical treatment applicators. The brachytherapy applicator dosimetry test object consists of a near full-scatter water tank with applicator and film supports constructed of Solid Water, accommodating any typical cervix applicator. Film dosimeters are precisely held in four orthogonal planes bisecting the intrauterine tube, sampling dose distributions in the high risk clinical target volume, points A and B, bladder, rectum and sigmoid. The applicator position is fixed prior to CT scanning and through treatment planning and irradiation. The CT data is acquired with the applicator in a near clinical orientation to include applicator reconstruction in the system test. Gamma analysis is used to compare treatment planning system exported RTDose grid with measured multi-channel film dose maps. Results from two pilot audits are presented, using Ir-192 and Co-60 HDR sources, with a mean gamma passing rate of 98.6% using criteria of 3% local normalization and 3 mm distance to agreement (DTA). The mean DTA between prescribed dose and measured film dose at point A was 1.2 mm. The phantom was funded by IPEM and will be used for a UK national brachytherapy dosimetry audit.

  1. Linear energy transfer dependence of a normoxic polymer gel dosimeter investigated using proton beam absorbed dose measurements

    NASA Astrophysics Data System (ADS)

    Gustavsson, Helen; Bäck, Sven Å. J.; Medin, Joakim; Grusell, Erik; Olsson, Lars E.

    2004-09-01

    Three-dimensional dosimetry with good spatial resolution can be performed using polymer gel dosimetry, which has been investigated for dosimetry of different types of particles. However, there are only sparse data concerning the influence of the linear energy transfer (LET) properties of the radiation on the gel absorbed dose response. The purpose of this study was to investigate possible LET dependence for a polymer gel dosimeter using proton beam absorbed dose measurements. Polymer gel containing the antioxidant tetrakis(hydroxymethyl)phosphonium (THP) was irradiated with 133 MeV monoenergetic protons, and the gel absorbed dose response was evaluated using MRI. The LET distribution for a monoenergetic proton beam was calculated as a function of depth using the Monte Carlo code PETRA. There was a steep increase in the Monte Carlo calculated LET starting at the depth corresponding to the front edge of the Bragg peak. This increase was closely followed by a decrease in the relative detector sensitivity (Srel = Dgel/Ddiode), indicating that the response of the polymer gel detector was dependent on LET. The relative sensitivity was 0.8 at the Bragg peak, and reached its minimum value at the end of the proton range. No significant effects in the detector response were observed for LET < 4.9 keV µm-1, thus indicating that the behaviour of the polymer gel dosimeter would not be altered for the range of LET values expected in the case of photons or electrons in a clinical range of energies.

  2. Mean Absorbed Dose to the Anal-Sphincter Region and Fecal Leakage among Irradiated Prostate Cancer Survivors

    SciTech Connect

    Alsadius, David; Hedelin, Maria; Lundstedt, Dan; Pettersson, Niclas; Wilderaeng, Ulrica; Steineck, Gunnar

    2012-10-01

    Purpose: To supplement previous findings that the absorbed dose of ionizing radiation to the anal sphincter or lower rectum affects the occurrence of fecal leakage among irradiated prostate-cancer survivors. We also wanted to determine whether anatomically defining the anal-sphincter region as the organ at risk could increase the degree of evidence underlying clinical guidelines for restriction doses to eliminate this excess risk. Methods and Materials: We identified 985 men irradiated for prostate cancer between 1993 and 2006. In 2008, we assessed long-term gastrointestinal symptoms among these men using a study-specific questionnaire. We restrict the analysis to the 414 men who had been treated with external beam radiation therapy only (no brachytherapy) to a total dose of 70 Gy in 2-Gy daily fractions to the prostate or postoperative prostatic region. On reconstructed original radiation therapy dose plans, we delineated the anal-sphincter region as an organ at risk. Results: We found that the prevalence of long-term fecal leakage at least once per month was strongly correlated with the mean dose to the anal-sphincter region. Examining different dose intervals, we found a large increase at 40 Gy; {>=}40 Gy compared with <40 Gy gave a prevalence ratio of 3.8 (95% confidence interval 1.6-8.6). Conclusions: This long-term study shows that mean absorbed dose to the anal-sphincter region is associated with the occurrence of long-term fecal leakage among irradiated prostate-cancer survivors; delineating the anal-sphincter region separately from the rectum and applying a restriction of a mean dose <40 Gy will, according to our data, reduce the risk considerably.

  3. Simulation studies on the effect of absorbers on dose distribution in rotational radiotherapy.

    PubMed

    Ivanova, T; Bliznakova, K; Malatara, G; Kardamakis, D; Kolitsi, Z; Pallikarakis, N

    2009-12-01

    The effect of cylindrical protector dimensions, material and distance from the source on the dose distribution in rotational radiotherapy was studied to assess the potential protection possibilities of small-sized radiosensitive structures, such as spinal cord. The dose distributions were evaluated in terms of dose at the protected region and surface dose, ratio of the dose at the protected region to the maximum dose, and dose gradient. High-density materials, such as lead, tungsten, gold and cerrobend, along with new polymer-metal composite ones were used in simulation studies, performed by an in-house developed Monte Carlo Radiotherapy Simulator. To ensure correct modeling of the composite materials, simulated attenuation data were verified against experimentally measured data. The dependence of the dose at the protected region from the protector diameter and the field size was established. Protectors of higher density and larger diameter provide not only lower dose at the protected region, but also steeper dose gradient and lower ratio of the dose at the protected region to the treatment dose. For the protection of small structures, high-density protectors placed further from the source allow thicker protectors to be used. The surface dose increases insignificantly for the studied protector-surface distances. The results have shown that shielding properties of composite materials are close to those of lead. PMID:19186088

  4. Reconstruction of Absorbed Doses to Fibroglandular Tissue of the Breast of Women undergoing Mammography (1960 to the Present)

    PubMed Central

    Thierry-Chef, Isabelle; Simon, Steven L.; Weinstock, Robert M.; Kwon, Deukwoo; Linet, Martha S.

    2013-01-01

    The assessment of potential benefits versus harms from mammographic examinations as described in the controversial breast cancer screening recommendations of the U.S. Preventive Task Force included limited consideration of absorbed dose to the fibroglandular tissue of the breast (glandular tissue dose), the tissue at risk for breast cancer. Epidemiological studies on cancer risks associated with diagnostic radiological examinations often lack accurate information on glandular tissue dose, and there is a clear need for better estimates of these doses. Our objective was to develop a quantitative summary of glandular tissue doses from mammography by considering sources of variation over time in key parameters including imaging protocols, x-ray target materials, voltage, filtration, incident air kerma, compressed breast thickness, and breast composition. We estimated the minimum, maximum, and mean values for glandular tissue dose for populations of exposed women within 5-year periods from 1960 to the present, with the minimum to maximum range likely including 90% to 95% of the entirety of the dose range from mammography in North America and Europe. Glandular tissue dose from a single view in mammography is presently about 2 mGy, about one-sixth the dose in the 1960s. The ratio of our estimates of maximum to minimum glandular tissue doses for average-size breasts was about 100 in the 1960s compared to a ratio of about 5 in recent years. Findings from our analysis provide quantitative information on glandular tissue doses from mammographic examinations which can be used in epidemiologic studies of breast cancer. PMID:21988547

  5. 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.

  6. Absorbed dose to man from the Se-75 labeled conjugated bile salt SeHCAT: concise communication

    SciTech Connect

    Soundy, R.G.; Simpson, J.D.; Ross, H.M.; Merrick, M.V.

    1982-02-01

    The absorbed radiation dose that would result from the oral or intravenous administration of SeHCAT (23-(75Se)selena-25-homotaurocholate) has been calculated using the MIRD tables and formulas and data from measurements of whole-body distribution and from long-term whole-body counting in rats, mice, and man. When SeHCAT is administered to normal subjects, the gallbladder is the critical organ, receiving 12 mrad (oral dose) or 22 mrad (i.v.) per microcurie. The whole-body dose is 1 mrad/microCi, whatever the route of administration. In severe hepatic failure the liver might receive 200 mrad/microCi. The activity likely to be used in routine clinical practice is 10 microCi. Where a whole-body counter is used, an activity of 1 microCi has proved adequate. Even at an administered activity of 25 microCi, the absorbed dose is small compared with established techniques of investigating the gastrointestinal tract.

  7. Absorbed dose to man from the Se-75 labeled conjugated bile salt SeHCAT: concise communication

    SciTech Connect

    Soundy, R.G.; Simpson, J.D.; Ross, H.M.; Merrick, M.V.

    1982-02-01

    The absorbed radiation dose that would result from the oral or intravenous administration of SeHCAT (23-(/sup 75/Se)selena-25-homotaurocholate) has been calculated using the MIRD tables and formulas and data from measurements of whole-body distribution and from long-term whole-body counting in rats, mice, and man. When SeHCAT is administered to normal subjects, the gallbladder is the critical organ, receiving 12 mrad (oral dose) or 22 mrad (i.v.) per microcurie. The whole-body dose is 1 mrad/..mu..Ci, whatever the route of administration. In severe hepatic failure the liver might receive 200 mrad/..mu..Ci. The activity likely to be used in routine clinical practice is 10 ..mu..Ci. Where a whole-body counter is used, an activity of 1 ..mu..Ci has proved adequate. Even at an administered activity of 25 ..mu..Ci, the absorbed dose is small compared with established techniques of investigating the gastrointestinal tract.

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

    SciTech Connect

    Wroe, Andrew Clasie, Ben; Kooy, Hanne; Flanz, Jay; Schulte, Reinhard; Rosenfeld, Anatoly

    2009-01-01

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

  9. Comparison of mathematical models for red marrow and blood absorbed dose estimation in the radioiodine treatment of advanced differentiated thyroid carcinoma

    NASA Astrophysics Data System (ADS)

    Miranti, A.; Giostra, A.; Richetta, E.; Gino, E.; Pellerito, R. E.; Stasi, M.

    2015-02-01

    Metastatic and recurrent differentiated thyroid carcinoma is preferably treated with 131I, whose administered activity is limited by red marrow (RM) toxicity, originally correlated by Benua to a blood absorbed dose higher than 2 Gy. Afterward a variety of dosimetric approaches has been proposed. The aim of this work is to compare the results of the Benua formula with the ones of other three blood and RM absorbed dose formulae. Materials and methods have been borrowed by the dosimetric protocol of the Italian Internal Dosimetry group and adapted to the routine of our centre. Wilcoxon t-tests and percentage differences have been applied for comparison purposes. Results are significantly different (p < 0.05) from each other, with an average percentage difference between Benua versus other results of -22%. The dosimetric formula applied to determine blood or RM absorbed dose may contribute significantly to increase heterogeneity in absorbed dose and dose-response results. Standardization should be a major objective.

  10. On the suitability of ultrathin detectors for absorbed dose assessment in the presence of high-density heterogeneities

    SciTech Connect

    Bueno, M. Duch, M. A.; Carrasco, P.; Jornet, N.; Muñoz-Montplet, C.

    2014-08-15

    Purpose: The aim of this study was to evaluate the suitability of several detectors for the determination of absorbed dose in bone. Methods: Three types of ultrathin LiF-based thermoluminescent dosimeters (TLDs)—two LiF:Mg,Cu,P-based (MCP-Ns and TLD-2000F) and a{sup 7}Li-enriched LiF:Mg,Ti-based (MTS-7s)—as well as EBT2 Gafchromic films were used to measure percentage depth-dose distributions (PDDs) in a water-equivalent phantom with a bone-equivalent heterogeneity for 6 and 18 MV and a set of field sizes ranging from 5×5 cm{sup 2} to 20×20 cm{sup 2}. MCP-Ns, TLD-2000F, MTS-7s, and EBT2 have active layers of 50, 20, 50, and 30 μm, respectively. Monte Carlo (MC) dose calculations (PENELOPE code) were used as the reference and helped to understand the experimental results and to evaluate the potential perturbation of the fluence in bone caused by the presence of the detectors. The energy dependence and linearity of the TLDs’ response was evaluated. Results: TLDs exhibited flat energy responses (within 2.5%) and linearity with dose (within 1.1%) within the range of interest for the selected beams. The results revealed that all considered detectors perturb the electron fluence with respect to the energy inside the bone-equivalent material. MCP-Ns and MTS-7s underestimated the absorbed dose in bone by 4%–5%. EBT2 exhibited comparable accuracy to MTS-7s and MCP-Ns. TLD-2000F was able to determine the dose within 2% accuracy. No dependence on the beam energy or field size was observed. The MC calculations showed that a50 μm thick detector can provide reliable dose estimations in bone regardless of whether it is made of LiF, water or EBT’s active layer material. Conclusions: TLD-2000F was found to be suitable for providing reliable absorbed dose measurements in the presence of bone for high-energy x-ray beams.

  11. Monte Carlo calculations and measurements of absorbed dose per monitor unit for the treatment of uveal melanoma with proton therapy

    PubMed Central

    Koch, Nicholas; Newhauser, Wayne D; Titt, Uwe; Gombos, Dan; Coombes, Kevin; Starkschall, George

    2014-01-01

    The treatment of uveal melanoma with proton radiotherapy has provided excellent clinical outcomes. However, contemporary treatment planning systems use simplistic dose algorithms that limit the accuracy of relative dose distributions. Further, absolute predictions of absorbed dose per monitor unit are not yet available in these systems. The purpose of this study was to determine if Monte Carlo methods could predict dose per monitor unit (D/MU) value at the center of a proton spread-out Bragg peak (SOBP) to within 1% on measured values for a variety of treatment fields relevant to ocular proton therapy. The MCNPX Monte Carlo transport code, in combination with realistic models for the ocular beam delivery apparatus and a water phantom, was used to calculate dose distributions and D/MU values, which were verified by the measurements. Measured proton beam data included central-axis depth dose profiles, relative cross-field profiles and absolute D/MU measurements under several combinations of beam penetration ranges and range-modulation widths. The Monte Carlo method predicted D/MU values that agreed with measurement to within 1% and dose profiles that agreed with measurement to within 3% of peak dose or within 0.5 mm distance-to-agreement. Lastly, a demonstration of the clinical utility of this technique included calculations of dose distributions and D/MU values in a realistic model of the human eye. It is possible to predict D/MU values accurately for clinical relevant range-modulated proton beams for ocular therapy using the Monte Carlo method. It is thus feasible to use the Monte Carlo method as a routine absolute dose algorithm for ocular proton therapy. PMID:18367789

  12. Spatial variations in natural background radiation: absorbed dose rates in air in Colorado.

    PubMed

    Stone, J M; Whicker, R D; Ibrahim, S A; Whicker, F W

    1999-05-01

    Large and small-scale spatial variations in natural ambient background radiation dose rates in Colorado were investigated at 1,150 specific locations with particular attention to 40 of the more populated areas along the Front Range of the Rocky Mountains. Total dose rates (including cosmic and terrestrial components) in Front Range communities below 2,000 m elevation averaged 135 nGy h(-1). Terrestrial dose rates had a coefficient of variation of 17%. Communities above 2,000 m had a mean total dose rate of 196 nGy h(-1), and a terrestrial dose rate coefficient of variation of 17%. Across all Front Range communities, the coefficient of variation for terrestrial dose rates was 22%. Within individual communities, coefficient of variation values for terrestrial dose rates ranged from 3 to 21%. Smaller-scale spatial variability (to within a few meters) was relatively small (coefficient of variation values generally ranged from 3 to 7%). A significant linear relationship (r2 = 0.83) between the size of area surveyed (km2) and coefficient of variation value for terrestrial dose rates was found. West of the Continental Divide, the terrestrial component accounted for roughly 60% of total measured dose rates, while east of the Continental Divide, where enriched granitic source rocks and associated soils are prevalent, the terrestrial component generally accounted for two-thirds or more of total dose rates. PMID:10201565

  13. Multiple myeloma among atomic bomb survivors in Hiroshima and Nagasaki, 1950-76: relationship to radiation dose absorbed by marrow

    SciTech Connect

    Ichimaru, M.; Ishimaru, T.; Mikami, M.; Matsunaga, M.

    1982-08-01

    The relationship between atomic bomb exposure and the incidence of multiple myeloma has been examined in a fixed cohort of atomic bomb survivors and controls in the life-span study sample for Hiroshima and Nagasaki. From October 1950 to December 1976, 29 cases of multiple myeloma were confirmed in this sample. Our analysis shows that the standardized relative risk (RR) adjusted for city, sex, and age at the time of bombings (ATB) increased with marrow-absorbed radiation dose. The increased RR does not appear to differ between cities or sexes and is demonstrable only for those survivors whose age ATB was between 20 and 59 years. The estimated risk in these individuals is approximately 0.48 cases/million person-years/rad for bone marrow total dose. This excess risk did not become apparent in individuals receiving 50 rad or more in marrow total dose until 20 years or more after exposure.

  14. Multiple myeloma among atomic bomb survivors in Hiroshima and Nagasaki, 1950-76: relationship to radiation dose absorbed by marrow

    SciTech Connect

    Ichimaru, M.; Ishimaru, T.; Mikami, M.; Matsunaga, M.

    1982-08-01

    The relationship between atomic bomb exposure and the incidence of multiple myeloma has been examined in a fixed cohort of atomic bomb survivors and controls in the life-span study sample for Hiroshima and Nagasaki. From October 1950 to December 1976, 29 cases of multiple myeloma were confirmed in this sample. Our analysis shows that the standardized relative risk (RR) adjusted for city, sex, and age at the time of bombings (ATB) increased with marrow-absorbed radiation dose. The increased RR does not appear to differ between cities or sexes and is demonstrable only for those survivors whose age ATB was between 20 and 59 years. The estimaged risk in these individuals is approximately 0.48 cases/million person-years/rad for bone marrow total dose. This excess risk did not become apparent in individuals receiving 50 rad or more in marrow total dose until 20 years or more after exposure.

  15. Calculation of. beta. -ray absorbed dose rate for /sup 131/I applied to the inflorescence of Tradescantia

    SciTech Connect

    Bingo, K.; Tano, S.; Numakunai, T.; Yoshida, Y.; Yamaguchi, H.

    1981-03-01

    Effects of /sup 131/I applied to the inflorescence on the induction of somatic mutations in Tradescantia stamen hairs were previously investigated, and the doubling dose (activity) was estimated to be 4 nCi. In the present paper, the absorbed dose rate in stamen hairs of Tradescantia for ..beta.. rays from the applied /sup 131/I was calculated. The doubling dose for the /sup 131/I (4 nCi) applied to the inflorescence was estimated to be higher than 0.3 rad (assuming uniform distribution of /sup 131/I on the surface of the buds and assuming that the shape of the buds was a sphere) and lower than 1.0 rad.

  16. Human absorbed dose estimation for a new (175)Yb-phosphonate based on rats data: Comparison with similar bone pain palliation agents.

    PubMed

    Vaez-Tehrani, Mahdokht; Zolghadri, Samaneh; Yousefnia, Hassan; Afarideh, Hossein

    2016-09-01

    In this work, the absorbed dose to human organs for (175)Yb-BPAMD was evaluated based on the biodistribution studies in rats. The results showed that the bone surface would receive the highest absorbed dose after injection of (175)Yb-BPAMD with 13.32mGy/MBq, while the other organs receive insignificant absorbed dose. Also, the comparison of (175)Yb-BPAMD with other therapeutic phosphonate complexes demonstrated noticeable characteristics for this new agent. Generally, based on the obtained results, (175)Yb-BPAMD can be considered as a promising agent for bone pain palliative therapy in near future. PMID:27337650

  17. Duration of salbutamol-induced bronchodilation delivered by metered-dose inhaler in mechanically ventilated COPD patients.

    PubMed

    Mouloudi, E; Maliotakis, C; Kondili, E; Kafetzakis, A; Georgopoulos, D

    2001-06-01

    The delivery of bronchodilators with metered-dose inhaler (MDI) and a spacer in mechanically ventilated patients has become a widespread practice. However, the duration of action of bronchodilators delivered with this technique is not well established. The purpose of the study was to examine the duration of bronchodilation induced by short-term beta 2-agonists administered with an MDI and a spacer in a group of mechanically ventilated patients with exacerbation of chronic obstructive pulmonary disease (COPD). Ten patients with COPD, mechanically ventilated on volume-controlled mode, received 6 puffs of salbutamol (S, 100 micrograms/puff). S was administered with an MDI adapted to the inspiratory limb of the ventilator circuit using an aerosol cloud enhance spacer. Static and dynamic airway pressures, minimum (Rint) and maximum (Rrs) inspiratory resistance, the difference between Rrs and Rint (delta R), static end-inspiratory system compliance (Cst, rs), intrinsic positive end-expiratory pressure (PEEPi) and heart rate (HR) were measured before and at 15, 30, 60, 120, 180, 240, 300, 360 min after S. S caused a significant decrease in dynamic and static airway pressures, PEEPi, Rint and Rrs. These changes were evident at 15 minutes and remained significant for 2 hours after S. The duration of bronchodilation was highly variable and unpredictable among patients, lasting in some patients more than 4 hours while in others wearing off in less than 2 hours. We conclude that 6 puffs of S delivered with an MDI and a spacer device induces significant bronchodilation in mechanically ventilated patients with COPD, the duration of which is highly variable precluding guidelines regarding the time scheduled for dosing.

  18. Accidental embryo irradiation during barium enema examinations: An estimation of absorbed dose

    SciTech Connect

    Damilakis, J.; Perisinakis, K.; Grammatikakis, J.

    1996-04-01

    The purpose of this report is to investigate the possibility of an embryo to receive a dose of more than 10 cGy, the threshold of malformation induction in embryos reported by the International Commission on Radiological Protection, during barium enema examinations. Thermoluminescent dosimeters were place in a phantom to calculate the depth-to-skin conversion coefficient needed for dose estimation at the average embryo depth in patients. Barium enema examinations were performed in 20 women of childbearing age with diagnostic problems demanding longer fluoroscopy times. Doses at 6 cm, the average embryo depth, were determined by measurements at the patients` skin followed by dose calculation at the site of interest. The range of doses estimated at embryo depth for patients was 1.9 to 8.2 cGy. The dose always exceeded 5 cGy when fluoroscopy time was longer than 7 minutes. The dose at the embryo depth never exceeded 10 cGy. This study indicates that fluoroscopy time should not exceed 7 minutes in childbearing-age female patients undergoing barium enema examinations. 6 refs., 1 fig., 2 tabs.

  19. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    SciTech Connect

    Aguiar, Vitor A. P.; Medina, Nilberto H.; Moreira, Ramon H.; Silveira, Marcilei A. G.

    2010-05-21

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely {sup 40}K, {sup 232}Th and {sup 238}U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

  20. Absorbed Gamma-Ray Doses due to Natural Radionuclides in Building Materials

    NASA Astrophysics Data System (ADS)

    Aguiar, Vitor A. P.; Medina, Nilberto H.; Moreira, Ramon H.; Silveira, Marcilei A. G.

    2010-05-01

    This work is devoted to the application of high-resolution gamma-ray spectrometry in the study of the effective dose coming from naturally occurring radionuclides, namely 40K, 232Th and 238U, present in building materials such as sand, cement, and granitic gravel. Four models were applied to estimate the effective dose and the hazard indices. The maximum estimated effective dose coming from the three reference rooms considered is 0.90(45) mSv/yr, and maximum internal hazard index is 0.77(24), both for the compact clay brick reference room. The principal gamma radiation sources are cement, sand and bricks.

  1. Evaluation of a deterministic grid-based Boltzmann solver (GBBS) for voxel-level absorbed dose calculations in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Mikell, Justin; Cheenu Kappadath, S.; Wareing, Todd; Erwin, William D.; Titt, Uwe; Mourtada, Firas

    2016-06-01

    To evaluate the 3D Grid-based Boltzmann Solver (GBBS) code ATTILA ® for coupled electron and photon transport in the nuclear medicine energy regime for electron (beta, Auger and internal conversion electrons) and photon (gamma, x-ray) sources. Codes rewritten based on ATTILA are used clinically for both high-energy photon teletherapy and 192Ir sealed source brachytherapy; little information exists for using the GBBS to calculate voxel-level absorbed doses in nuclear medicine. We compared DOSXYZnrc Monte Carlo (MC) with published voxel-S-values to establish MC as truth. GBBS was investigated for mono-energetic 1.0, 0.1, and 0.01 MeV electron and photon sources as well as 131I and 90Y radionuclides. We investigated convergence of GBBS by analyzing different meshes ({{M}0},{{M}1},{{M}2} ), energy group structures ({{E}0},{{E}1},{{E}2} ) for each radionuclide component, angular quadrature orders (≤ft. {{S}4},{{S}8},{{S}16}\\right) , and scattering order expansions ({{P}0} –{{P}6} ); higher indices imply finer discretization. We compared GBBS to MC in (1) voxel-S-value geometry for soft tissue, lung, and bone, and (2) a source at the interface between combinations of lung, soft tissue, and bone. Excluding Auger and conversion electrons, MC agreed within  ≈5% of published source voxel absorbed doses. For the finest discretization, most GBBS absorbed doses in the source voxel changed by less than 1% compared to the next finest discretization along each phase space variable indicating sufficient convergence. For the finest discretization, agreement with MC in the source voxel ranged from  ‑3% to  ‑20% with larger differences at lower energies (‑3% for 1 MeV electron in lung to  ‑20% for 0.01 MeV photon in bone); similar agreement was found for the interface geometries. Differences between GBBS and MC in the source voxel for 90Y and 131I were  ‑6%. The GBBS ATTILA was benchmarked against MC in the nuclear medicine regime. GBBS can be a

  2. Evaluation of a deterministic grid-based Boltzmann solver (GBBS) for voxel-level absorbed dose calculations in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Mikell, Justin; Cheenu Kappadath, S.; Wareing, Todd; Erwin, William D.; Titt, Uwe; Mourtada, Firas

    2016-06-01

    To evaluate the 3D Grid-based Boltzmann Solver (GBBS) code ATTILA ® for coupled electron and photon transport in the nuclear medicine energy regime for electron (beta, Auger and internal conversion electrons) and photon (gamma, x-ray) sources. Codes rewritten based on ATTILA are used clinically for both high-energy photon teletherapy and 192Ir sealed source brachytherapy; little information exists for using the GBBS to calculate voxel-level absorbed doses in nuclear medicine. We compared DOSXYZnrc Monte Carlo (MC) with published voxel-S-values to establish MC as truth. GBBS was investigated for mono-energetic 1.0, 0.1, and 0.01 MeV electron and photon sources as well as 131I and 90Y radionuclides. We investigated convergence of GBBS by analyzing different meshes ({{M}0},{{M}1},{{M}2} ), energy group structures ({{E}0},{{E}1},{{E}2} ) for each radionuclide component, angular quadrature orders (≤ft. {{S}4},{{S}8},{{S}16}\\right) , and scattering order expansions ({{P}0} -{{P}6} ); higher indices imply finer discretization. We compared GBBS to MC in (1) voxel-S-value geometry for soft tissue, lung, and bone, and (2) a source at the interface between combinations of lung, soft tissue, and bone. Excluding Auger and conversion electrons, MC agreed within  ≈5% of published source voxel absorbed doses. For the finest discretization, most GBBS absorbed doses in the source voxel changed by less than 1% compared to the next finest discretization along each phase space variable indicating sufficient convergence. For the finest discretization, agreement with MC in the source voxel ranged from  -3% to  -20% with larger differences at lower energies (-3% for 1 MeV electron in lung to  -20% for 0.01 MeV photon in bone); similar agreement was found for the interface geometries. Differences between GBBS and MC in the source voxel for 90Y and 131I were  -6%. The GBBS ATTILA was benchmarked against MC in the nuclear medicine regime. GBBS can be a viable

  3. Evaluation of a deterministic grid-based Boltzmann solver (GBBS) for voxel-level absorbed dose calculations in nuclear medicine.

    PubMed

    Mikell, Justin; Cheenu Kappadath, S; Wareing, Todd; Erwin, William D; Titt, Uwe; Mourtada, Firas

    2016-06-21

    To evaluate the 3D Grid-based Boltzmann Solver (GBBS) code ATTILA (®) for coupled electron and photon transport in the nuclear medicine energy regime for electron (beta, Auger and internal conversion electrons) and photon (gamma, x-ray) sources. Codes rewritten based on ATTILA are used clinically for both high-energy photon teletherapy and (192)Ir sealed source brachytherapy; little information exists for using the GBBS to calculate voxel-level absorbed doses in nuclear medicine. We compared DOSXYZnrc Monte Carlo (MC) with published voxel-S-values to establish MC as truth. GBBS was investigated for mono-energetic 1.0, 0.1, and 0.01 MeV electron and photon sources as well as (131)I and (90)Y radionuclides. We investigated convergence of GBBS by analyzing different meshes ([Formula: see text]), energy group structures ([Formula: see text]) for each radionuclide component, angular quadrature orders ([Formula: see text], and scattering order expansions ([Formula: see text]-[Formula: see text]); higher indices imply finer discretization. We compared GBBS to MC in (1) voxel-S-value geometry for soft tissue, lung, and bone, and (2) a source at the interface between combinations of lung, soft tissue, and bone. Excluding Auger and conversion electrons, MC agreed within  ≈5% of published source voxel absorbed doses. For the finest discretization, most GBBS absorbed doses in the source voxel changed by less than 1% compared to the next finest discretization along each phase space variable indicating sufficient convergence. For the finest discretization, agreement with MC in the source voxel ranged from  -3% to  -20% with larger differences at lower energies (-3% for 1 MeV electron in lung to  -20% for 0.01 MeV photon in bone); similar agreement was found for the interface geometries. Differences between GBBS and MC in the source voxel for (90)Y and (131)I were  -6%. The GBBS ATTILA was benchmarked against MC in the nuclear medicine regime. GBBS can be a

  4. Evaluation of a deterministic grid-based Boltzmann solver (GBBS) for voxel-level absorbed dose calculations in nuclear medicine.

    PubMed

    Mikell, Justin; Cheenu Kappadath, S; Wareing, Todd; Erwin, William D; Titt, Uwe; Mourtada, Firas

    2016-06-21

    To evaluate the 3D Grid-based Boltzmann Solver (GBBS) code ATTILA (®) for coupled electron and photon transport in the nuclear medicine energy regime for electron (beta, Auger and internal conversion electrons) and photon (gamma, x-ray) sources. Codes rewritten based on ATTILA are used clinically for both high-energy photon teletherapy and (192)Ir sealed source brachytherapy; little information exists for using the GBBS to calculate voxel-level absorbed doses in nuclear medicine. We compared DOSXYZnrc Monte Carlo (MC) with published voxel-S-values to establish MC as truth. GBBS was investigated for mono-energetic 1.0, 0.1, and 0.01 MeV electron and photon sources as well as (131)I and (90)Y radionuclides. We investigated convergence of GBBS by analyzing different meshes ([Formula: see text]), energy group structures ([Formula: see text]) for each radionuclide component, angular quadrature orders ([Formula: see text], and scattering order expansions ([Formula: see text]-[Formula: see text]); higher indices imply finer discretization. We compared GBBS to MC in (1) voxel-S-value geometry for soft tissue, lung, and bone, and (2) a source at the interface between combinations of lung, soft tissue, and bone. Excluding Auger and conversion electrons, MC agreed within  ≈5% of published source voxel absorbed doses. For the finest discretization, most GBBS absorbed doses in the source voxel changed by less than 1% compared to the next finest discretization along each phase space variable indicating sufficient convergence. For the finest discretization, agreement with MC in the source voxel ranged from  -3% to  -20% with larger differences at lower energies (-3% for 1 MeV electron in lung to  -20% for 0.01 MeV photon in bone); similar agreement was found for the interface geometries. Differences between GBBS and MC in the source voxel for (90)Y and (131)I were  -6%. The GBBS ATTILA was benchmarked against MC in the nuclear medicine regime. GBBS can be a

  5. Experimental determination of the absorbed dose to water in a scanned proton beam using a water calorimeter and an ionization chamber

    NASA Astrophysics Data System (ADS)

    Gagnebin, Solange; Twerenbold, Damian; Pedroni, Eros; Meer, David; Zenklusen, Silvan; Bula, Christian

    2010-03-01

    The absorbed dose to water is the reference physical quantity for the energy absorbed in tissue when exposed to beams of ionizing radiation in radiotherapy. The SI unit of absorbed dose to water is the gray (Gy = 1 J/kg). Ionization chambers are used as the dosimeters of choice in the clinical environment because they show a high reproducibility and are easy to use. However, ionization chambers have to be calibrated in order to convert the measured electrical charge into absorbed dose to water. In addition, protocols require these conversion factors to be SI traceable to a primary standard of absorbed dose to water. We present experimental results where the ionization chamber used for the dosimetry for the scanned proton beam facility at PSI is compared with the direct determination of absorbed dose to water from the METAS primary standard water calorimeter. The agreement of 3.2% of the dose values measured by the two techniques are within their respective statistical uncertainties.

  6. Verification of Entrance Dose Measurements with Thermoluminescent Dosimeters in Conventional Radiotherapy Procedures Delivered with Co-60 Teletherapy Machine

    PubMed Central

    Evwierhurhoma, OB; Ibitoye, ZA; Ojieh, CA; Duncan, JTK

    2015-01-01

    Background: The use of in vivo dosimetry with thermolumiscent dosimeters (TLDs) as a veritable means of quality control in conventional radiotherapy procedures was determined in this work. Aim: The objective of this study was to determine the role of in vivo dosimetry with thermoluminescent dosimeters (TLDs) as part of quality control and audit in conventional radiotherapy procedures delivered with Co-60 teletherapy machine. Subjects and Methods: Fifty-seven patients with cancers of the breast, pelvis, head and neck were admitted for this study. TLD system at the Radiation Monitoring and Protection Centre, Lagos State University, Ojo, Lagos-Nigeria was used for the in vivo entrance dose readings. All patients were treated with Co-60 (T780c) teletherapy machine at 80 cm source to surface distance located at Eko Hospitals, Lagos. Two TLDs were placed on the patient surface within 1 cm from the center of the field of treatment. Build-up material made of paraffin wax with a density of 0.939 g/cm3 and a thickness 0.5 cm was placed on top of the TLDs. A RADOS RE 200 TLD reader was used to read out the TLDs over 12 s and at a temperature of 300°C. Results: The results showed that there was no significant difference between the expected dose and measured dose of breast (P = 0.11), H and N (P = 0.52), and pelvis (P = 0.31) patients. Furthermore, percentage difference between expected dose and measured dose of the three treatment sites were not significantly different (P = 0.11). More so, 88.9% (16/18) treated breast, 91.3% (21/23) pelvis, and 86.7% (13/15) H and N patients had percentage deviation difference less than 5%. In general, 89.3% (50/56) patients admitted for this study had their percentage deviation difference below 5% recommended standard limit. Conclusion: The values obtained establish that there are no major differences from similar studies reported in literature. This study was also part of quality control and audit of the radiotherapy procedures in the

  7. SU-E-T-29: A Web Application for GPU-Based Monte Carlo IMRT/VMAT QA with Delivered Dose Verification

    SciTech Connect

    Folkerts, M; Graves, Y; Tian, Z; Gu, X; Jia, X; Jiang, S

    2014-06-01

    Purpose: To enable an existing web application for GPU-based Monte Carlo (MC) 3D dosimetry quality assurance (QA) to compute “delivered dose” from linac logfile data. Methods: We added significant features to an IMRT/VMAT QA web application which is based on existing technologies (HTML5, Python, and Django). This tool interfaces with python, c-code libraries, and command line-based GPU applications to perform a MC-based IMRT/VMAT QA. The web app automates many complicated aspects of interfacing clinical DICOM and logfile data with cutting-edge GPU software to run a MC dose calculation. The resultant web app is powerful, easy to use, and is able to re-compute both plan dose (from DICOM data) and delivered dose (from logfile data). Both dynalog and trajectorylog file formats are supported. Users upload zipped DICOM RP, CT, and RD data and set the expected statistic uncertainty for the MC dose calculation. A 3D gamma index map, 3D dose distribution, gamma histogram, dosimetric statistics, and DVH curves are displayed to the user. Additional the user may upload the delivery logfile data from the linac to compute a 'delivered dose' calculation and corresponding gamma tests. A comprehensive PDF QA report summarizing the results can also be downloaded. Results: We successfully improved a web app for a GPU-based QA tool that consists of logfile parcing, fluence map generation, CT image processing, GPU based MC dose calculation, gamma index calculation, and DVH calculation. The result is an IMRT and VMAT QA tool that conducts an independent dose calculation for a given treatment plan and delivery log file. The system takes both DICOM data and logfile data to compute plan dose and delivered dose respectively. Conclusion: We sucessfully improved a GPU-based MC QA tool to allow for logfile dose calculation. The high efficiency and accessibility will greatly facilitate IMRT and VMAT QA.

  8. Development and verification of an analytical algorithm to predict absorbed dose distributions in ocular proton therapy using Monte Carlo simulations.

    PubMed

    Koch, Nicholas C; Newhauser, Wayne D

    2010-02-01

    Proton beam radiotherapy is an effective and non-invasive treatment for uveal melanoma. Recent research efforts have focused on improving the dosimetric accuracy of treatment planning and overcoming the present limitation of relative analytical dose calculations. Monte Carlo algorithms have been shown to accurately predict dose per monitor unit (D/MU) values, but this has yet to be shown for analytical algorithms dedicated to ocular proton therapy, which are typically less computationally expensive than Monte Carlo algorithms. The objective of this study was to determine if an analytical method could predict absolute dose distributions and D/MU values for a variety of treatment fields like those used in ocular proton therapy. To accomplish this objective, we used a previously validated Monte Carlo model of an ocular nozzle to develop an analytical algorithm to predict three-dimensional distributions of D/MU values from pristine Bragg peaks and therapeutically useful spread-out Bragg peaks (SOBPs). Results demonstrated generally good agreement between the analytical and Monte Carlo absolute dose calculations. While agreement in the proximal region decreased for beams with less penetrating Bragg peaks compared with the open-beam condition, the difference was shown to be largely attributable to edge-scattered protons. A method for including this effect in any future analytical algorithm was proposed. Comparisons of D/MU values showed typical agreement to within 0.5%. We conclude that analytical algorithms can be employed to accurately predict absolute proton dose distributions delivered by an ocular nozzle.

  9. Modeling of Dose Distribution for a Proton Beam Delivering System with the use of the Multi-Particle Transport Code 'Fluka'

    SciTech Connect

    Mumot, Marta; Agapov, Alexey

    2007-11-26

    We have developed a new delivering system for hadron therapy which uses a multileaf collimator and a range shifter. We simulate our delivering beam system with the multi-particle transport code 'Fluka'. From these simulations we obtained information about the dose distributions, about stars generated in the delivering system elements and also information about the neutron flux. All the informations obtained were analyzed from the point of view of radiation protection, homogeneity of beam delivery to patient body, and also in order to improve some modifiers used.

  10. [Spatial distribution of local absorbed doses inside the Russian segment of the International Space Station].

    PubMed

    Bondarenko, V A; Mitrikas, V G; Tsetlin, V V

    2011-01-01

    The article discusses the procedure of operational radiation safety monitoring with the use of portable Pille-MKS dosimeters, presents the results of ISS dose measurements from September 22, 2003 (after Pille deployment on board the ISS) to March 16, 2011 (completion of the ISS-25 mission). The necessity of continuous dynamic tracking of the radiation environment in ISS compartments arises from the character and uniqueness of space ionizing radiation effects on crew. Radiation loading in the ISS compartments was analyzed and results of using different dosimeters were compared. Experimental radiation studies of the ISS piloted compartments are needed for reliable prediction of doses for the crew that still defy precise estimation. PMID:21970039

  11. Detector photon response and absorbed dose and their applications to rapid triage techniques

    NASA Astrophysics Data System (ADS)

    Voss, Shannon Prentice

    As radiation specialists, one of our primary objectives in the Navy is protecting people and the environment from the effects of ionizing and non-ionizing radiation. Focusing on radiological dispersal devices (RDD) will provide increased personnel protection as well as optimize emergency response assets for the general public. An attack involving an RDD has been of particular concern because it is intended to spread contamination over a wide area and cause massive panic within the general population. A rapid method of triage will be necessary to segregate the unexposed and slightly exposed from those needing immediate medical treatment. Because of the aerosol dispersal of the radioactive material, inhalation of the radioactive material may be the primary exposure route. The primary radionuclides likely to be used in a RDD attack are Co-60, Cs-137, Ir-192, Sr-90 and Am-241. Through the use of a MAX phantom along with a few Simulink MATLAB programs, a good anthropomorphic phantom was created for use in MCNPX simulations that would provide organ doses from internally deposited radionuclides. Ludlum model 44-9 and 44-2 detectors were used to verify the simulated dose from the MCNPX code. Based on the results, acute dose rate limits were developed for emergency response personnel that would assist in patient triage.

  12. Tumoral fibrosis effect on the radiation absorbed dose of (177)Lu-Tyr(3)-octreotate and (177)Lu-Tyr(3)-octreotate conjugated to gold nanoparticles.

    PubMed

    Azorín-Vega, E P; Zambrano-Ramírez, O D; Rojas-Calderón, E L; Ocampo-García, B E; Ferro-Flores, G

    2015-06-01

    The aim of this work was to evaluate the tumoral fibrosis effect on the radiation absorbed dose of the radiopharmaceuticals (177)Lu-Tyr(3)-octreotate (monomeric) and (177)Lu-Tyr(3)-octreotate-gold nanoparticles (multimeric) using an experimental HeLa cells tumoral model and the Monte Carlo PENELOPE code. Experimental and computer micro-environment models with or without fibrosis were constructed. Results showed that fibrosis increases up to 33% the tumor radiation absorbed dose, although the major effect on the dose was produced by the type of radiopharmaceutical (112Gy-multimeric vs. 43Gy-monomeric).

  13. Tumoral fibrosis effect on the radiation absorbed dose of (177)Lu-Tyr(3)-octreotate and (177)Lu-Tyr(3)-octreotate conjugated to gold nanoparticles.

    PubMed

    Azorín-Vega, E P; Zambrano-Ramírez, O D; Rojas-Calderón, E L; Ocampo-García, B E; Ferro-Flores, G

    2015-06-01

    The aim of this work was to evaluate the tumoral fibrosis effect on the radiation absorbed dose of the radiopharmaceuticals (177)Lu-Tyr(3)-octreotate (monomeric) and (177)Lu-Tyr(3)-octreotate-gold nanoparticles (multimeric) using an experimental HeLa cells tumoral model and the Monte Carlo PENELOPE code. Experimental and computer micro-environment models with or without fibrosis were constructed. Results showed that fibrosis increases up to 33% the tumor radiation absorbed dose, although the major effect on the dose was produced by the type of radiopharmaceutical (112Gy-multimeric vs. 43Gy-monomeric). PMID:25305748

  14. Absorbed Radiation Dose in Radiosensitive Organs Using 64- and 320-Row Multidetector Computed Tomography: A Comparative Study

    PubMed Central

    Khan, Atif N.; Nikolic, Boris; Khan, Mohammad K.; Kang, Jian; Khosa, Faisal

    2014-01-01

    Aim. To determine absorbed radiation dose (ARD) in radiosensitive organs during prospective and full phase dose modulation using ECG-gated MDCTA scanner under 64- and 320-row detector modes. Methods. Female phantom was used to measure organ radiation dose. Five DP-3 radiation detectors were used to measure ARD to lungs, breast, and thyroid using the Aquilion ONE scanner in 64- and 320-row modes using both prospective and dose modulation in full phase acquisition. Five measurements were made using three tube voltages: 100, 120, and 135 kVp at 400 mA at heart rate (HR) of 60 and 75 bpm for each protocol. Mean acquisition was recorded in milligrays (mGy). Results. Mean ARD was less for 320-row versus 64-row mode for each imaging protocol. Prospective EKG-gated imaging protocol resulted in a statistically lower ARD using 320-row versus 64-row modes for midbreast (6.728 versus 19.687 mGy, P < 0.001), lung (6.102 versus 21.841 mGy, P < 0.001), and thyroid gland (0.208 versus 0.913 mGy; P < 0.001). Retrospective imaging using 320- versus 64-row modes showed lower ARD for midbreast (10.839 versus 43.169 mGy, P < 0.001), lung (8.848 versus 47.877 mGy, P < 0.001), and thyroid gland (0.057 versus 2.091 mGy; P < 0.001). ARD reduction was observed at lower kVp and heart rate. Conclusions. Dose reduction to radiosensitive organs is achieved using 320-row compared to 64-row modes for both prospective and retrospective gating, whereas 64-row mode is equivalent to the same model 64-row MDCT scanner. PMID:25170427

  15. A radiochromic folm dosimeter for gamma radiation in the absorbed-dose range 0.1-10 kGy

    NASA Astrophysics Data System (ADS)

    Khan, Hasan M.; Farahani, Mahnaz; William L., McLaughlin

    A commercially available leuco-dye film (FWT-63-02), having a thickness of 0.55 mm, has been investigated spectrophotometrically for its characteristics as a radiochromic dosimeter and for its potential use in food-irradiation applications. The γ-ray irradiation of the nearly colorless, transparent film induces blue color with an absorption maximum at 600 nm. The increase in absorbance at 600 nm per unit thickness of film (Δ A mm -1) is linear with dose in the dose range up to 8 kGy, with a slope of 0.91 mm -1·kGy -1. After a modest additional increase during the first day following irradiation, the radiation-induced color is stable when stored at room temperature at least for 5 weeks. The response slope is 16% higher when stored at 60°C, however, after the initial 1-day increase it is stable for several weeks when stored at that temperature. The response of the dosimeter is independent of dose rate in the range 0.5-170 Gy min -1.

  16. Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Flampouri, Stella; Jiang, Steve B.; Sharp, Greg C.; Wolfgang, John; Patel, Abhijit A.; Choi, Noah C.

    2006-06-01

    The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the

  17. Estimation of the delivered patient dose in lung IMRT treatment based on deformable registration of 4D-CT data and Monte Carlo simulations.

    PubMed

    Flampouri, Stella; Jiang, Steve B; Sharp, Greg C; Wolfgang, John; Patel, Abhijit A; Choi, Noah C

    2006-06-01

    The purpose of this study is to accurately estimate the difference between the planned and the delivered dose due to respiratory motion and free breathing helical CT artefacts for lung IMRT treatments, and to estimate the impact of this difference on clinical outcome. Six patients with representative tumour motion, size and position were selected for this retrospective study. For each patient, we had acquired both a free breathing helical CT and a ten-phase 4D-CT scan. A commercial treatment planning system was used to create four IMRT plans for each patient. The first two plans were based on the GTV as contoured on the free breathing helical CT set, with a GTV to PTV expansion of 1.5 cm and 2.0 cm, respectively. The third plan was based on the ITV, a composite volume formed by the union of the CTV volumes contoured on free breathing helical CT, end-of-inhale (EOI) and end-of-exhale (EOE) 4D-CT. The fourth plan was based on GTV contoured on the EOE 4D-CT. The prescribed dose was 60 Gy for all four plans. Fluence maps and beam setup parameters of the IMRT plans were used by the Monte Carlo dose calculation engine MCSIM for absolute dose calculation on both the free breathing CT and 4D-CT data. CT deformable registration between the breathing phases was performed to estimate the motion trajectory for both the tumour and healthy tissue. Then, a composite dose distribution over the whole breathing cycle was calculated as a final estimate of the delivered dose. EUD values were computed on the basis of the composite dose for all four plans. For the patient with the largest motion effect, the difference in the EUD of CTV between the planed and the delivered doses was 33, 11, 1 and 0 Gy for the first, second, third and fourth plan, respectively. The number of breathing phases required for accurate dose prediction was also investigated. With the advent of 4D-CT, deformable registration and Monte Carlo simulations, it is feasible to perform an accurate calculation of the

  18. The development of early pediatric models and their application to radiation absorbed dose calculations

    SciTech Connect

    Poston, J.W.

    1989-12-31

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The ``pediatric`` models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing ``individual`` pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. will be discussed.

  19. The development of early pediatric models and their application to radiation absorbed dose calculations

    SciTech Connect

    Poston, J.W.

    1989-01-01

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The pediatric'' models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing individual'' pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. will be discussed.

  20. SU-E-CAMPUS-T-01: Analysis of the Precision of Patient Set-Up, and Fidelity of the Delivered Dose Distribution in Proton Therapy of Ocular Tumors

    SciTech Connect

    Trofimov, A; Carpenter, K; Shih, HA

    2014-06-15

    Purpose: To quantify daily set-up variations in fractionated proton therapy of ocular melanomas, and to assess the effect on the fidelity of delivered distribution to the plan. Methods: In a typical five-fraction course, daily set-up is achieved by matching the position of fiducial markers in orthogonal radiographs to the images generated by treatment planning program. A patient maintains the required gaze direction voluntarily, without the aid of fixation devices. Confirmation radiographs are acquired to assess intrafractional changes. For this study, daily radiographs were analyzed to determine the daily iso-center position and apparent gaze direction, which were then transferred to the planning system to calculate the dose delivered in individual fractions, and accumulated dose for the entire course. Dose-volume metrics were compared between the planned and accumulated distributions for the tumor and organs at risk, for representative cases that varied by location within the ocular globe. Results: The analysis of the first set of cases (3 posterior, 3 transequatorial and 4 anterior tumors) revealed varying dose deviation patterns, depending on the tumor location. For anterior and posterior tumors, the largest dose increases were observed in the lens and ciliary body, while for the equatorial tumors, macula, optic nerve and disk, were most often affected. The iso-center position error was below 1.3 mm (95%-confidence interval), and the standard deviation of daily polar and azimuthal gaze set-up were 1.5 and 3 degrees, respectively. Conclusion: We quantified interfractional and intrafractional set-up variation, and estimated their effect on the delivered dose for representative cases. Current safety margins are sufficient to maintain the target coverage, however, the dose delivered to critical structures often deviates from the plan. The ongoing analysis will further explore the patterns of dose deviation, and may help to identify particular treatment scenarios

  1. TOPICAL REVIEW: Advances in the determination of absorbed dose to water in clinical high-energy photon and electron beams using ionization chambers

    NASA Astrophysics Data System (ADS)

    Saiful Huq, M.; Andreo, Pedro

    2004-02-01

    During the last two decades, absorbed dose to water in clinical photon and electron beams was determined using dosimetry protocols and codes of practice based on radiation metrology standards of air kerma. It is now recommended that clinical reference dosimetry be based on standards of absorbed dose to water. Newer protocols for the dosimetry of radiotherapy beams, based on the use of an ionization chamber calibrated in terms of absorbed dose to water, ND,w, in a standards laboratory's reference quality beam, have been published by several national or regional scientific societies and international organizations. Since the publication of these protocols multiple theoretical and experimental dosimetry comparisons between the various ND,w based recommendations, and between the ND,w and the former air kerma (NK) based protocols, have been published. This paper provides a comprehensive review of the dosimetry protocols based on these standards and of the intercomparisons of the different protocols published in the literature, discussing the reasons for the observed discrepancies between them. A summary of the various types of standards of absorbed dose to water, together with an analysis of the uncertainties along the various steps of the dosimetry chain for the two types of formalism, is also included. It is emphasized that the NK-ND,air and ND,w formalisms have very similar uncertainty when the same criteria are used for both procedures. Arguments are provided in support of the recommendation for a change in reference dosimetry based on standards of absorbed dose to water.

  2. Influence of the characteristic curve on the clinical image quality and patient absorbed dose in lumbar spine radiography

    NASA Astrophysics Data System (ADS)

    Tingberg, Anders; Herrmann, Clemens; Lanhede, Birgitta; Almen, Anja; Mattsson, Saron; Panzer, Werner; Besjakov, Jack; Mansson, Lars G.; Kheddache, Susanne; Zankl, Maria

    2001-06-01

    The 'European Guidelines on Quality Criteria for Diagnostic Radiographic Images' do not address the choice of film characteristic (H/D) curve, which is an important parameter for the description of a radiographic screen-film system. Since it is not possible to investigate this influence by taking repeated exposures of the same patients on films with systematically varied H/D curves, patient images of lumbar spine were digitised in the current study. The image contrast was altered by digital image processing techniques, simulating images with H/D curves varying from flat over standard latitude to a film type steeper than a mammography film. The manipulated images were printed on film for evaluation. Seven European radiologists evaluated the clinical image quality of in total 224 images by analysing the fulfilment of the European Image Criteria and by visual grading analysis of the images. The results show that the local quality can be significantly improved by the application of films with a steeper film H/D curve compared to the standard latitude film. For images with an average optical density of about 1.25, the application of the steeper film results in a reduction of patient absorbed dose by about 10-15% without a loss of diagnostically relevant image information. The results also show that the patient absorbed dose reduction obtained by altering the tube voltage from 70 kV to 90 kV coincides with a loss of image information that cannot be compensated for by simply changing the shape of the H/D curve.

  3. A graphite calorimeter for absolute measurements of absorbed dose to water: application in medium-energy x-ray filtered beams

    NASA Astrophysics Data System (ADS)

    Pinto, M.; Pimpinella, M.; Quini, M.; D'Arienzo, M.; Astefanoaei, I.; Loreti, S.; Guerra, A. S.

    2016-02-01

    The Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI) has designed and built a graphite calorimeter that, in a water phantom, has allowed the determination of the absorbed dose to water in medium-energy x-rays with generating voltages from 180 to 250 kV. The new standard is a miniaturized three-bodies calorimeter, with a disc-shaped core of 21 mm diameter and 2 mm thickness weighing 1.134 g, sealed in a PMMA waterproof envelope with air-evacuated gaps. The measured absorbed dose to graphite is converted into absorbed dose to water by means of an energy-dependent conversion factor obtained from Monte Carlo simulations. Heat-transfer correction factors were determined by FEM calculations. At a source-to-detector distance of 100 cm, a depth in water of 2 g cm-2, and at a dose rate of about 0.15 Gy min-1, results of calorimetric measurements of absorbed dose to water, D w, were compared to experimental determinations, D wK, obtained via an ionization chamber calibrated in terms of air kerma, according to established dosimetry protocols. The combined standard uncertainty of D w and D wK were estimated as 1.9% and 1.7%, respectively. The two absorbed dose to water determinations were in agreement within 1%, well below the stated measurement uncertainties. Advancements are in progress to extend the measurement capability of the new in-water-phantom graphite calorimeter to other filtered medium-energy x-ray qualities and to reduce the D w uncertainty to around 1%. The new calorimeter represents the first implementation of in-water-phantom graphite calorimetry in the kilovoltage range and, allowing independent determinations of D w, it will contribute to establish a robust system of absorbed dose to water primary standards for medium-energy x-ray beams.

  4. SU-E-T-86: Comparison of Two Commercially Available Programs for the Evaluation of Delivered Daily Dose Using Cone Beam CT (CBCT)

    SciTech Connect

    Tuohy, R; Bosse, C; Mavroidis, P; Shi, Z; Crownover, R; Papanikolaou, N; Stathakis, S

    2014-06-01

    Purpose: In this study, two commercially available programs were compared for the evaluation of delivered daily dose using cone beam CT (CBCT). Methods: Thirty (n=30) patients previously treated in our clinic (10 prostate, 10 SBRT lung and 10 abdomen) were used in this study. The patients' plans were optimized and calculated using the Pinnacle treatment planning system. The daily CBCT scans were imported into Velocity and RayStation along with the corresponding planning CTs, structure sets and 3D dose distributions for each patient. The organs at risk (OAR) were contoured on each CBCT by the prescribing physician and were included in the evaluation of the daily delivered dose. Each CBCT was registered to the planning CT, once with rigid registration and then again, separately, with deformable registration. After registering each CBCT, the dose distribution from the planning CT was overlaid and the dose volume histograms (DVH) for the OAR and the planning target volumes (PTV) were calculated. Results: For prostate patients, we observed daily volume changes for the OARs. The DVH analysis for those patients showed variation in the sparing of the OARs while PTV coverage remained virtually unchanged using both Velocity and RayStation systems. Similar results were observed for abdominal patients. In contrast, for SBRT lung patients, the DVH for the OARs and target were comparable to those from the initial treatment plan. Differences in organ volume and organ doses were also observed when comparing the daily fractions using deformable and rigid registrations. Conclusion: By using daily CBCT dose reconstruction, we proved PTV coverage for prostate and abdominal targets is adequate. However, there is significant dosimetric change for the OARs. For lung SBRT patients, the delivered daily dose for both PTV and OAR is comparable to the planned dose with no significant differences.

  5. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    NASA Astrophysics Data System (ADS)

    Bakar, Khomsaton Abu; Ahmad, Pauzi; Zulkafli, Hashim, Siti A'aisah

    2014-09-01

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD5, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  6. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    SciTech Connect

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A'aisah; Ahmad, Pauzi

    2014-09-03

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD{sub 5}, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  7. Toward the development of transcriptional biodosimetry for the identification of irradiated individuals and assessment of absorbed radiation dose.

    PubMed

    Brzóska, Kamil; Kruszewski, Marcin

    2015-08-01

    The most frequently used and the best established method of biological dosimetry at present is the dicentric chromosome assay, which is poorly suitable for a mass casualties scenario. This gives rise to the need for the development of new, high-throughput assays for rapid identification of the subjects exposed to ionizing radiation. In the present study, we tested the usefulness of gene expression analysis in blood cells for biological dosimetry. Human peripheral blood from three healthy donors was X-irradiated with doses of 0 (control), 0.6, and 2 Gy. The mRNA level of 16 genes (ATF3, BAX, BBC3, BCL2, CDKN1A, DDB2, FDXR, GADD45A, GDF15, MDM2, PLK3, SERPINE1, SESN2, TNFRSF10B, TNFSF4, and VWCE) was assessed by reverse transcription quantitative PCR 6, 12, 24, and 48 h after exposure with ITFG1 and DPM1 used as a reference genes. The panel of radiation-responsive genes was selected comprising GADD45A, CDKN1A, BAX, BBC3, DDB2, TNFSF4, GDF15, and FDXR. Cluster analysis showed that ΔC t values of the selected genes contained sufficient information to allow discrimination between irradiated and non-irradiated blood samples. The samples were clearly grouped according to the absorbed doses of radiation and not to the time interval after irradiation or to the blood donor. PMID:25972268

  8. Estimated human absorbed dose of ¹⁷⁷Lu-BPAMD based on mice data: Comparison with ¹⁷⁷Lu-EDTMP.

    PubMed

    Yousefnia, Hassan; Zolghadri, Samaneh; Shanehsazzadeh, Saeed

    2015-10-01

    In this work, the absorbed dose of human organs for (177)Lu-BPAMD was evaluated based on biodistribution studies into the Syrian mice by RADAR method and was compared with (177)Lu-EDTMP as the only clinically used Lu-177 bone-seeking agent. The highest absorbed dose for both (177)Lu-BPAMD and (177)Lu-EDTMP is observed on the bone surface with 8.007 and 4.802 mSv/MBq. Generally, (177)Lu-BPAMD has considerable characteristics compared with (177)Lu-EDTMP and can be considered as a promising agent for the bone pain palliation therapy. PMID:26163291

  9. Accuracy and optimal timing of activity measurements in estimating the absorbed dose of radioiodine in the treatment of Graves' disease

    NASA Astrophysics Data System (ADS)

    Merrill, S.; Horowitz, J.; Traino, A. C.; Chipkin, S. R.; Hollot, C. V.; Chait, Y.

    2011-02-01

    Calculation of the therapeutic activity of radioiodine 131I for individualized dosimetry in the treatment of Graves' disease requires an accurate estimate of the thyroid absorbed radiation dose based on a tracer activity administration of 131I. Common approaches (Marinelli-Quimby formula, MIRD algorithm) use, respectively, the effective half-life of radioiodine in the thyroid and the time-integrated activity. Many physicians perform one, two, or at most three tracer dose activity measurements at various times and calculate the required therapeutic activity by ad hoc methods. In this paper, we study the accuracy of estimates of four 'target variables': time-integrated activity coefficient, time of maximum activity, maximum activity, and effective half-life in the gland. Clinical data from 41 patients who underwent 131I therapy for Graves' disease at the University Hospital in Pisa, Italy, are used for analysis. The radioiodine kinetics are described using a nonlinear mixed-effects model. The distributions of the target variables in the patient population are characterized. Using minimum root mean squared error as the criterion, optimal 1-, 2-, and 3-point sampling schedules are determined for estimation of the target variables, and probabilistic bounds are given for the errors under the optimal times. An algorithm is developed for computing the optimal 1-, 2-, and 3-point sampling schedules for the target variables. This algorithm is implemented in a freely available software tool. Taking into consideration 131I effective half-life in the thyroid and measurement noise, the optimal 1-point time for time-integrated activity coefficient is a measurement 1 week following the tracer dose. Additional measurements give only a slight improvement in accuracy.

  10. Comparison of testicular dose delivered by intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with prostate cancer.

    PubMed

    Martin, Jeffrey M; Handorf, Elizabeth A; Price, Robert A; Cherian, George; Buyyounouski, Mark K; Chen, David Y; Kutikov, Alexander; Johnson, Matthew E; Ma, Chung-Ming Charlie; Horwitz, Eric M

    2015-01-01

    A small decrease in testosterone level has been documented after prostate irradiation, possibly owing to the incidental dose to the testes. Testicular doses from prostate external beam radiation plans with either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) were calculated to investigate any difference. Testicles were contoured for 16 patients being treated for localized prostate cancer. For each patient, 2 plans were created: 1 with IMRT and 1 with VMAT. No specific attempt was made to reduce testicular dose. Minimum, maximum, and mean doses to the testicles were recorded for each plan. Of the 16 patients, 4 received a total dose of 7800 cGy to the prostate alone, 7 received 8000 cGy to the prostate alone, and 5 received 8000 cGy to the prostate and pelvic lymph nodes. The mean (range) of testicular dose with an IMRT plan was 54.7 cGy (21.1 to 91.9) and 59.0 cGy (25.1 to 93.4) with a VMAT plan. In 12 cases, the mean VMAT dose was higher than the mean IMRT dose, with a mean difference of 4.3 cGy (p = 0.019). There was a small but statistically significant increase in mean testicular dose delivered by VMAT compared with IMRT. Despite this, it unlikely that there is a clinically meaningful difference in testicular doses from either modality.

  11. Comparison of testicular dose delivered by intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with prostate cancer

    SciTech Connect

    Martin, Jeffrey M.; Handorf, Elizabeth A.; Price, Robert A.; Cherian, George; Buyyounouski, Mark K.; Chen, David Y.; Kutikov, Alexander; Johnson, Matthew E.; Ma, Chung-Ming Charlie; Horwitz, Eric M.

    2015-10-01

    A small decrease in testosterone level has been documented after prostate irradiation, possibly owing to the incidental dose to the testes. Testicular doses from prostate external beam radiation plans with either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) were calculated to investigate any difference. Testicles were contoured for 16 patients being treated for localized prostate cancer. For each patient, 2 plans were created: 1 with IMRT and 1 with VMAT. No specific attempt was made to reduce testicular dose. Minimum, maximum, and mean doses to the testicles were recorded for each plan. Of the 16 patients, 4 received a total dose of 7800 cGy to the prostate alone, 7 received 8000 cGy to the prostate alone, and 5 received 8000 cGy to the prostate and pelvic lymph nodes. The mean (range) of testicular dose with an IMRT plan was 54.7 cGy (21.1 to 91.9) and 59.0 cGy (25.1 to 93.4) with a VMAT plan. In 12 cases, the mean VMAT dose was higher than the mean IMRT dose, with a mean difference of 4.3 cGy (p = 0.019). There was a small but statistically significant increase in mean testicular dose delivered by VMAT compared with IMRT. Despite this, it unlikely that there is a clinically meaningful difference in testicular doses from either modality.

  12. SU-E-T-205: Improving Quality Assurance of HDR Brachytherapy: Verifying Agreement Between Planned and Delivered Dose Distributions Using DICOM RTDose and Advanced Film Dosimetry

    SciTech Connect

    Palmer, A L; Bradley, D A; Nisbet, A

    2014-06-01

    Purpose: HDR brachytherapy is undergoing significant development, and quality assurance (QA) checks must keep pace. Current recommendations do not adequately verify delivered against planned dose distributions: This is particularly relevant for new treatment planning system (TPS) calculation algorithms (non TG-43 based), and an era of significant patient-specific plan optimisation. Full system checks are desirable in modern QA recommendations, complementary to device-centric individual tests. We present a QA system incorporating TPS calculation, dose distribution export, HDR unit performance, and dose distribution measurement. Such an approach, more common in external beam radiotherapy, has not previously been reported in the literature for brachytherapy. Methods: Our QA method was tested at 24 UK brachytherapy centres. As a novel approach, we used the TPS DICOM RTDose file export to compare planned dose distribution with that measured using Gafchromic EBT3 films placed around clinical brachytherapy treatment applicators. Gamma analysis was used to compare the dose distributions. Dose difference and distance to agreement were determined at prescription Point A. Accurate film dosimetry was achieved using a glass compression plate at scanning to ensure physically-flat films, simultaneous scanning of known dose films with measurement films, and triple-channel dosimetric analysis. Results: The mean gamma pass rate of RTDose compared to film-measured dose distributions was 98.1% at 3%(local), 2 mm criteria. The mean dose difference, measured to planned, at Point A was -0.5% for plastic treatment applicators and -2.4% for metal applicators, due to shielding not accounted for in TPS. The mean distance to agreement was 0.6 mm. Conclusion: It is recommended to develop brachytherapy QA to include full-system verification of agreement between planned and delivered dose distributions. This is a novel approach for HDR brachytherapy QA. A methodology using advanced film

  13. Angular distributions of absorbed dose of Bremsstrahlung and secondary electrons induced by 18-, 28- and 38-MeV electron beams in thick targets.

    PubMed

    Takada, Masashi; Kosako, Kazuaki; Oishi, Koji; Nakamura, Takashi; Sato, Kouichi; Kamiyama, Takashi; Kiyanagi, Yoshiaki

    2013-03-01

    Angular distributions of absorbed dose of Bremsstrahlung photons and secondary electrons at a wide range of emission angles from 0 to 135°, were experimentally obtained using an ion chamber with a 0.6 cm(3) air volume covered with or without a build-up cap. The Bremsstrahlung photons and electrons were produced by 18-, 28- and 38-MeV electron beams bombarding tungsten, copper, aluminium and carbon targets. The absorbed doses were also calculated from simulated photon and electron energy spectra by multiplying simulated response functions of the ion chambers, simulated with the MCNPX code. Calculated-to-experimental (C/E) dose ratios obtained are from 0.70 to 1.57 for high-Z targets of W and Cu, from 15 to 135° and the C/E range from 0.6 to 1.4 at 0°; however, the values of C/E for low-Z targets of Al and C are from 0.5 to 1.8 from 0 to 135°. Angular distributions at the forward angles decrease with increasing angles; on the other hand, the angular distributions at the backward angles depend on the target species. The dependences of absorbed doses on electron energy and target thickness were compared between the measured and simulated results. The attenuation profiles of absorbed doses of Bremsstrahlung beams at 0, 30 and 135° were also measured.

  14. SU-E-CAMPUS-I-06: Y90 PET/CT for the Instantaneous Determination of Both Target and Non-Target Absorbed Doses Following Hepatic Radioembolization

    SciTech Connect

    Pasciak, A; Kao, J

    2014-06-15

    Purpose The process of converting Yttrium-90 (Y90) PET/CT images into 3D absorbed dose maps will be explained. The simple methods presented will allow the medical physicst to analyze Y90 PET images following radioembolization and determine the absorbed dose to tumor, normal liver parenchyma and other areas of interest, without application of Monte-Carlo radiation transport or dose-point-kernel (DPK) convolution. Methods Absorbed dose can be computed from Y90 PET/CT images based on the premise that radioembolization is a permanent implant with a constant relative activity distribution after infusion. Many Y90 PET/CT publications have used DPK convolution to obtain 3D absorbed dose maps. However, this method requires specialized software limiting clinical utility. The Local Deposition method, an alternative to DPK convolution, can be used to obtain absorbed dose and requires no additional computer processing. Pixel values from regions of interest drawn on Y90 PET/CT images can be converted to absorbed dose (Gy) by multiplication with a scalar constant. Results There is evidence that suggests the Local Deposition method may actually be more accurate than DPK convolution and it has been successfully used in a recent Y90 PET/CT publication. We have analytically compared dose-volume-histograms (DVH) for phantom hot-spheres to determine the difference between the DPK and Local Deposition methods, as a function of PET scanner point-spread-function for Y90. We have found that for PET/CT systems with a FWHM greater than 3.0 mm when imaging Y90, the Local Deposition Method provides a more accurate representation of DVH, regardless of target size than DPK convolution. Conclusion Using the Local Deposition Method, post-radioembolization Y90 PET/CT images can be transformed into 3D absorbed dose maps of the liver. An interventional radiologist or a Medical Physicist can perform this transformation in a clinical setting, allowing for rapid prediction of treatment efficacy by

  15. First international comparison of primary absorbed dose to water standards in the medium-energy X-ray range

    NASA Astrophysics Data System (ADS)

    Büermann, Ludwig; Guerra, Antonio Stefano; Pimpinella, Maria; Pinto, Massimo; de Pooter, Jacco; de Prez, Leon; Jansen, Bartel; Denoziere, Marc; Rapp, Benjamin

    2016-01-01

    This report presents the results of the first international comparison of primary measurement standards of absorbed dose to water for the medium-energy X-ray range. Three of the participants (VSL, PTB, LNE-LNHB) used their existing water calorimeter based standards and one participant (ENEA) recently developed a new standard based on a water-graphite calorimeter. The participants calibrated three transfer chambers of the same type in terms of absorbed dose to water (NDw) and in addition in terms of air kerma (NK) using the CCRI radiation qualities in the range 100 kV to 250 kV. The additional NK values were intended to be used for a physical analysis of the ratios NDw/NK. All participants had previously participated in the BIPM.RI(I)-K3 key comparison of air kerma standards. Ratios of pairs of NMI's NK results of the current comparison were found to be consistent with the corresponding key comparison results within the expanded uncertainties of 0.6 % - 1 %. The NDw results were analysed in terms of the degrees of equivalence with the comparison reference values which were calculated for each beam quality as the weighted means of all results. The participant's results were consistent with the reference value within the expanded uncertainties. However, these expanded uncertainties varied significantly and ranged between about 1-1.8 % for the water calorimeter based standards and were estimated at 3.7 % for the water-graphite calorimeter. It was shown previously that the ratios NDw/NK for the type of ionization chamber used as transfer chamber in this comparison were very close (within less than 1 %) to the calculated values of (bar muen/ρ)w,ad, the mean values of the water-to-air ratio of the mass-energy-absorption coefficients at the depth d in water. Some of the participant's results deviated significantly from the expected behavior. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of

  16. Multimodality image guided total marrow irradiation and verification of the dose delivered to the lung, PTV, and thoracic bone in a patient: a case study.

    PubMed

    Hui, Susanta K; Verneris, M R; Froelich, Jerry; Dusenbery, K; Welsh, James S

    2009-02-01

    This work reports our initial experience using multimodality image guidance to improve total marrow irradiation (TMI) using helical tomotherapy. We also monitored the details of the treatment delivery to glean information necessary for the implementation of future adaptive processes. A patient with metastatic Ewing's sarcoma underwent MRI, and bone scan imaging prior to TMI. A whole body kilovoltage CT (kVCT) scan was obtained for intensity modulated TMI treatment planning, including a boost treatment to areas of bony involvement. The delivered dose was estimated by using MVCT images from the helical tomotherapy treatment unit, compared to the expected dose distributions mapped onto the kVCT images. Clinical concerns regarding patient treatment and dosimetric uncertainties were also evaluated. A small fraction of thoracic bone volume received lower radiation dose than the prescribed dose. Reconstructed planned treatment volume (PTV) and the dose delivered to the lung were identical to planned dose. Bone scan imaging had a higher sensitivity for detecting skeletal metastasis compared to MR imaging. However the bone scan lacked sufficient specificity in three dimensions to be useful for planning conformal radiation boost treatments. Inclusion of appropriate imaging modalities improves detection of metastases, which allows the possibility of a radiation dose boost to metastases during TMI. Conformal intensity modulated radiation therapy via helical tomotherapy permitted radiation delivery to metastases in the skull with reduced dose to brain in conjunction with TMI. While TMI reduces irradiation to the lungs, onboard megavoltage computed tomography (MVCT) to verify accurate volumetric dose coverage to marrow-containing thoracic bones may be essential for successful conformal TMI treatment.

  17. SU-E-T-516: Measurement of the Absorbed Dose Rate in Water Under Reference Conditions in a CyberKnife Unit

    SciTech Connect

    Aragon-Martinez, N; Hernandez-Guzman, A; Gomez-Munoz, A; Massillon-JL, G

    2014-06-01

    Purpose: This paper aims to measure the absorbed-dose-rate in a CyberKnife unit reference-field (6cm diameter) using three ionization chambers (IC) following the new IAEA/AAPM formalism and Gafchromic film (MD-V3-55 and EBT3) protocol according to our work reported previously. Methods: The absorbed-dose-rates were measured at 90cm and 70cm SSD in a 10cmx10cm field and at 70cm SSD in a 5.4cmx5.4cm equivalent to 6cm diameter field using a linac Varian iX. All measurements were performed at 10cm depth in water. The correction factors that account for the difference between the IC response on the reference field and the CyberKnife reference field, k-(Q-msr,Q)^(f-msr,f-ref), were evaluated and Gafchromic film were calibrated using the results obtained above. Under the CyberKnife reference conditions, the factors were used to measure the absorbed-dose-rate with IC according to the new formalism and the calibrated film was irradiated in water. The film calibration curve was used to evaluate the absorbed-dose-rate in the CyberKnife unit. Results: Difference up to 2.56% is observed between dose-rate measured with IC in the reference 10cmx10cm field, depending where the chamber was calibrated, which was not reflected in the correction factor k-(Q-msr,Q)^(f-msr,f-ref ) where variations of ~0.15%-0.5% were obtained. Within measurements uncertainties, maximum difference of 1.8% on the absorbed-dose-rate in the CyberKnife reference field is observed between all IC and the films Conclusion: Absorbed-dose-rate to water was measured in a CyberKnife reference field with acceptable accuracy (combined uncertainties ~1.32%-1.73%, k=1) using three IC and films. The MD-V3-55 film as well as the new IAEA/AAPM formalism can be considered as a suitable dosimetric method to measure absorbed-dose-rate to water in small and non-standard CyberKnife fields used in clinical treatments However, the EBT3 film is not appropriated due to the high uncertainty provided (combined uncertainty ~9%, k=1

  18. Relative Importance of Hip and Sacral Pain Among Long-Term Gynecological Cancer Survivors Treated With Pelvic Radiotherapy and Their Relationships to Mean Absorbed Doses

    SciTech Connect

    Waldenstroem, Ann-Charlotte; Olsson, Caroline; Wilderaeng, Ulrica; Dunberger, Gail; Lind, Helena; Alevronta, Eleftheria; Al-Abany, Massoud; Tucker, Susan; Avall-Lundqvist, Elisabeth; Johansson, Karl-Axel; Steineck, Gunnar

    2012-10-01

    Purpose: To investigate the relative importance of patient-reported hip and sacral pain after pelvic radiotherapy (RT) for gynecological cancer and its relationship to the absorbed doses in these organs. Methods and Materials: We used data from a population-based study that included 650 long-term gynecological cancer survivors treated with pelvic RT in the Gothenburg and Stockholm areas in Sweden with a median follow-up of 6 years (range, 2-15) and 344 population controls. Symptoms were assessed through a study-specific postal questionnaire. We also analyzed the hip and sacral dose-volume histogram data for 358 of the survivors. Results: Of the survivors, one in three reported having or having had hip pain after completing RT. Daily pain when walking was four times as common among the survivors compared to controls. Symptoms increased in frequency with a mean absorbed dose >37.5 Gy. Also, two in five survivors reported pain in the sacrum. Sacral pain also affected their walking ability and tended to increase with a mean absorbed dose >42.5 Gy. Conclusions: Long-term survivors of gynecological cancer treated with pelvic RT experience hip and sacral pain when walking. The mean absorbed dose was significantly related to hip pain and was borderline significantly related to sacral pain. Keeping the total mean absorbed hip dose below 37.5 Gy during treatment might lower the occurrence of long-lasting pain. In relation to the controls, the survivors had a lower occurrence of pain and pain-related symptoms from the hips and sacrum compared with what has previously been reported for the pubic bone.

  19. The effect of systematic set-up deviations on the absorbed dose distribution for left-sided breast cancer treated with respiratory gating

    NASA Astrophysics Data System (ADS)

    Edvardsson, A.; Ceberg, S.

    2013-06-01

    The aim of this study was 1) to investigate interfraction set-up uncertainties for patients treated with respiratory gating for left-sided breast cancer, 2) to investigate the effect of the inter-fraction set-up on the absorbed dose-distribution for the target and organs at risk (OARs) and 3) optimize the set-up correction strategy. By acquiring multiple set-up images the systematic set-up deviation was evaluated. The effect of the systematic set-up deviation on the absorbed dose distribution was evaluated by 1) simulation in the treatment planning system and 2) measurements with a biplanar diode array. The set-up deviations could be decreased using a no action level correction strategy. Not using the clinically implemented adaptive maximum likelihood factor for the gating patients resulted in better set-up. When the uncorrected set-up deviations were simulated the average mean absorbed dose was increased from 1.38 to 2.21 Gy for the heart, 4.17 to 8.86 Gy to the left anterior descending coronary artery and 5.80 to 7.64 Gy to the left lung. Respiratory gating can induce systematic set-up deviations which would result in increased mean absorbed dose to the OARs if not corrected for and should therefore be corrected for by an appropriate correction strategy.

  20. A 3-Dimensional Absorbed Dose Calculation Method Based on Quantitative SPECT for Radionuclide Therapy: Evaluation for 131I Using Monte Carlo Simulation

    PubMed Central

    Ljungberg, Michael; Sjögreen, Katarina; Liu, Xiaowei; Frey, Eric; Dewaraja, Yuni; Strand, Sven-Erik

    2009-01-01

    A general method is presented for patient-specific 3-dimensional absorbed dose calculations based on quantitative SPECT activity measurements. Methods The computational scheme includes a method for registration of the CT image to the SPECT image and position-dependent compensation for attenuation, scatter, and collimator detector response performed as part of an iterative reconstruction method. A method for conversion of the measured activity distribution to a 3-dimensional absorbed dose distribution, based on the EGS4 (electron-gamma shower, version 4) Monte Carlo code, is also included. The accuracy of the activity quantification and the absorbed dose calculation is evaluated on the basis of realistic Monte Carlo–simulated SPECT data, using the SIMIND (simulation of imaging nuclear detectors) program and a voxel-based computer phantom. CT images are obtained from the computer phantom, and realistic patient movements are added relative to the SPECT image. The SPECT-based activity concentration and absorbed dose distributions are compared with the true ones. Results Correction could be made for object scatter, photon attenuation, and scatter penetration in the collimator. However, inaccuracies were imposed by the limited spatial resolution of the SPECT system, for which the collimator response correction did not fully compensate. Conclusion The presented method includes compensation for most parameters degrading the quantitative image information. The compensation methods are based on physical models and therefore are generally applicable to other radionuclides. The proposed evaluation methodology may be used as a basis for future intercomparison of different methods. PMID:12163637

  1. Comparison of Accuracy in Calculation of Absorbed Dose to Patients Following Bone Scan with 99mTc-Marked Diphosphonates by Two Different Background Correction Methods

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Damoori, Mehri; Tavakoli, Mohammad Bagher; Moslehi, Masoud

    2016-01-01

    To improve the accuracy of the activity quantification and the image quality in scintigraphy, scatter correction is a vital procedure. The aim of this study is to compare the accuracy in calculation of absorbed dose to patients following bone scan with 99mTc-marked diphosphonates (99mTc-MDP) by two different methods of background correction in conjugate view method. This study involved 22 patients referring to the Nuclear Medicine Center of Shahid Chamran Hospital, Isfahan, Iran. After the injection of 99mTc-MDP, whole-body images from patients were acquired at 10, 60, 90, and 180 min. Organ activities were calculated using the conjugate view method by Buijs and conventional background correction. Finally, the absorbed dose was calculated using the Medical Internal Radiation Dosimetry (MIRD) technique. The results of this study showed that the absorbed dose per unit of injected activity (rad/mCi) ± standard deviation for pelvis bone, bladder, and kidneys by Buijs method was 0.19 ± 0.05, 0.08 ± 0.01, and 0.03 ± 0.01 and by conventional method was 0.13 ± 0.04, 0.08 ± 0.01, and 0.024 ± 0.01, respectively. This showed that Buijs background correction method had a high accuracy compared to conventional method for the estimated absorbed dose of bone and kidneys whereas, for the bladder, its accuracy was low. PMID:27014610

  2. Absorbed dose estimates for positron emission tomography (PET): C/sup 15/O, /sup 11/CO, and CO/sup 15/O

    SciTech Connect

    Kearfott, K.J.

    1982-11-01

    Regional cerebral blood volume and blood flow may be determined using PET and C/sup 15/O, /sup 11/CO, and CO/sup 15/O. Detailed estimates of radiation absorbed dose for 22 organs and the whole body are reported and compared for these gases administered by continuous or bolus inhalation and by infusion techniques.

  3. Evaluation of absorbed dose in irradiated sugar-containing plant material (peony roots) by an ESR method

    NASA Astrophysics Data System (ADS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2015-12-01

    The relationship between electron spin resonance (ESR) signal intensity of irradiated plant materials and sugar content was investigated by spectral analysis using peony roots. A weak background signal near g=2.005 was observed in the roots. After a 10 kGy irradiation, the ESR line broadened and the intensity increased, and the spectral characteristics were similar to a typical spectrum of irradiated food containing crystalline sugars. The free radical concentration was nearly stable 30 days after irradiation. The spectrum of peony root 30 days after irradiation was simulated using the summation of the intensities of six assumed components: radical signals derived from (a) sucrose, (b) glucose, (c) fructose, (d) cellulose, (e) the background signal near g=2.005 and (f) unidentified component. The simulated spectra using the six components were in agreement with the observed sample spectra. The intensity of sucrose radical signal in irradiated samples increased proportionally up to 20 kGy. In addition, the intensity of sucrose radical signals was strongly correlated with the sucrose contents of the samples. The results showed that the radiation sensitivity of sucrose in peony roots was influenced little by other plant constituents. There was also a good correlation between the total area of the spectra and the sucrose content, because the sucrose content was higher than that of other sugars in the samples. In peony roots, estimation of the absorbed dose from the ESR signal intensity may be possible by a calibration method based on the sucrose content.

  4. Determination of absorbed dose of ozone (O3) in animals and humans using stable-isotope (oxygen-18) tracing

    SciTech Connect

    Hatch, G.E.; Aissa, M.

    1987-05-01

    A method for the determination of absorbed dose of ozone (O3) in animals and humans using oxygen-18 YO as a physiological tracer is presented. The experimental aspects of the method are based on the instantaneous pyrolysis of tissue samples and subsequent conversion of the sample oxygen to carbon monoxide then to carbon dioxide whose isotopic composition is determined by isotope-ratio mass spectrometry. A mathematical procedure is then used to correct the isotopic data for interferences from the blank and memory effects and from the iodine pentoxide oxidation of CO to CO2. Laboratory animals were exposed to YO3 (1 ppm, 1 hr) then tissues were dried and processed for YO measurement. Enrichments in YO over natural abundance YO was observed in lung homogenates, nasal cavities, trachea, and pulmonary lavage fluids but not in blood of mice, rats, and rabbits. Thus, the YO tracing method appears to be sensitive enough to detect the reaction products of YO in animals exposed to near environmental concentrations of this gas.

  5. Comparison of the NMIJ and the ARPANSA standards for absorbed dose to water in high-energy photon beams.

    PubMed

    Shimizu, M; Morishita, Y; Kato, M; Tanaka, T; Kurosawa, T; Takata, N; Saito, N; Ramanathan, G; Harty, P D; Oliver, C; Wright, T; Butler, D J

    2015-04-01

    The authors report the results of an indirect comparison of the standards of absorbed dose to water in high-energy photon beams from a clinical linac and (60)Co radiation beam performed between the National Metrology Institute of Japan (NMIJ) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Three ionisation chambers were calibrated by the NMIJ in April and June 2013 and by the ARPANSA in May 2013. The average ratios of the calibration coefficients for the three ionisation chambers obtained by the NMIJ to those obtained by the ARPANSA were 0.9994, 1.0040 and 1.0045 for 6-, 10- and 15-MV (18 MV at the ARPANSA) high-energy photon beams, respectively. The relative standard uncertainty of the value was 7.2 × 10(-3). The ratio for (60)Co radiation was 0.9986(66), which is consistent with the results published in the key comparison of BIPM.RI(I)-K4.

  6. Determination of absorbed dose in high-energy electron and photon radiation by means of an uncalibrated ionization chamber.

    PubMed

    Klevenhagen, S C

    1991-02-01

    The aim of this study was to develop a dosimetric method based on an ionization chamber which has an uncalibrated sensitive volume but which behaves as a Bragg-Gray cavity in high-energy radiation. The new type of chamber developed in the course of this study has a variable volume and is constructed from water-similar materials. It can be used in a water phantom directly in a beam of a therapy megavoltage machine under clinical conditions. The chamber allows absorbed dose to be determined from first principles, overcoming many of the problems encountered with conventional dosimetry based on calibrated chambers. The study involved an intercomparison of the performance of the new chamber in high-energy electron and photon radiation with the conventional calibrated chambers employed according to the established dosimetry protocols. Good agreement was found between these dosimetric methods and it may therefore be concluded that the method developed in this work can be successfully employed for absolute dosimetry. The new chamber is a promising device for research in various aspects of dosimetry.

  7. Evaluation of radiation dose delivered by cone beam CT and tomosynthesis employed for setup of external breast irradiation

    SciTech Connect

    Winey, Brian; Zygmanski, Piotr; Lyatskaya, Yulia

    2009-01-15

    A systematic set of measurements is reported for evaluation of doses to critical organs resulting from cone-beam CT (CB-CT) and cone-beam tomosynthesis (CB-TS) as applied to breast setup for external beam irradiation. The specific focus of this study was on evaluation of doses from these modalities in a setting of volumetric breast imaging for target localization in radiotherapy treatments with the goal of minimizing radiation to healthy organs. Ion chamber measurements were performed in an anthropomorphic female thorax phantom at the center of each breast and lung and on the phantom surface at one anterior and two lateral locations (seven points total). The measurements were performed for three different isocenters located at the center of the phantom and at offset locations of the right and left breast. The dependence of the dose on angle selection for the CB-TS arc was also studied. For the most typical situation of centrally located CB-CT isocenter the measured doses ranged between 3 and 7 cGy, in good agreement with previous reports. Dose measurements were performed for a range of start/stop angles commonly used for CB-TS and the impact of direct and scatter dose on organs at risk was analyzed. All measured CB-TS doses were considerably lower than CB-CT doses, with greater decrease in dose for the organs outside of the beam (up to 98% decrease in dose). Remarkably, offsetting the isocenter towards the ipsilateral breast resulted on average to additional 46% dose reduction to organs at risk. The lowest doses to the contralateral breast and lung were less than 0.1 cGy when they were measured for the offset isocenter. The biggest reduction in dose was obtained by using CB-TS beams that completely avoid the critical organ. For points inside the CB-TS beam, the dose was reduced in a linear relation with distance from the center of the imaging arc. The data indicate that it is possible to reduce substantially radiation doses to the contralateral organs by proper

  8. Do We Need Daily Image-Guided Radiotherapy by Megavoltage Computed Tomography in Head and Neck Helical Tomotherapy? The Actual Delivered Dose to the Spinal Cord

    SciTech Connect

    Duma, Marciana Nona; Kampfer, Severin; Schuster, Tibor; Aswathanarayana, Nandana; Fromm, Laura-Sophie; Molls, Michael; Andratschke, Nicolaus; Geinitz, Hans

    2012-09-01

    Purpose: To quantify the actual delivered dose to the cervical spinal cord with different image-guided radiotherapy (IGRT) approaches during head and neck (HN) cancer helical tomotherapy. Methods and Materials: Twenty HN patients (HNpts) treated with bilateral nodal irradiation were analyzed. Daily megavoltage computed tomography MVCT) scans were performed for setup purposes. The maximum dose on the planning CT scan (plan-Dmax) and the magnitude and localization of the actual delivered Dmax (a-Dmax) were analyzed for four scenarios: daily image-guided radiotherapy (dIGRT), twice weekly IGRT (2 Multiplication-Sign WkIGRT), once weekly IGRT (1 Multiplication-Sign WkIGRT), and no IGRT at all (non-IGRT). The spinal cord was recontoured on 236 MVCTs for each scenario (total, 944 fractions), and the delivered dose was recalculated for each fraction (fx) separately. Results: Fifty-one percent of the analyzed fx for dIGRT, 56% of the analyzed fx for the 2 Multiplication-Sign WkIGRT, 62% of the analyzed fx for the 1 Multiplication-Sign WkIGRT, and 63% of the analyzed fx for the non-IGRT scenarios received a higher a-Dmax than the plan-Dmax. The median increase of dose in these fx was 3.3% more for dIGRT, 5.8% more for 2 Multiplication-Sign WkIGRT, 10.0% more for 1 Multiplication-Sign WkIGRT, and 9.5% more for non-IGRT than the plan-Dmax. The median spinal cord volumes receiving a higher dose than the plan-Dmax were 0.02 cm{sup 3} for dIGRT, 0.11 cm{sup 3} for 2 Multiplication-Sign WkIGRT, 0.31 cm{sup 3} for 1 Multiplication-Sign WkIGRT, and 0.22 cm{sup 3} for non-IGRT. Differences between the dIGRT and all other scenarios were statistically significant (p < 0.05). Conclusions: Compared to the Dmax of the initial plan, daily IGRT had the smallest increase in dose. Furthermore, daily IGRT had the lowest proportion of fractions and the smallest volumes affected by a dose that was higher than the planned dose. For patients treated with doses close to the tolerance dose of the

  9. Case control study to assess the possibility of decrease the risk of osteoradionecrosis in relation to the dose of radiation absorbed by the jaw

    PubMed Central

    Carini, Fabrizio; Bucalo, Concetta; Saggese, Vito; Monai, Dario; Porcaro, Gianluca

    2012-01-01

    Summary Aims the assessment of the limit dose for the organs at risk in external radiotherapy is a fundamental step to guarantee an optimal risk-benefit ratio. The aim of this study was to assess, through contouring the single dental cavities, the absorbed radiation dose on irradiated alveolar bones during the treatment of cervico-facial tumours, so as to test the correlation between the absorbed dose of radiation at alveolar level and the level of individual surgical risk for osteonecrosis. Materials and methods we selected 45 out of 89 patients on the basis of different exclusion criteria. Nine of these patients showed evidence of osteoradionecrosis. The patients were treated either with 3D conformational radiation therapy (3D-CRT) or with intensity-modulated radiation therapy (IMRT), there after alveolar bones were contoured using computed axial tomography (CAT scans) carried out following oncological and dental treatment. The dose-volume histograms (DVH) were obtained on the basis of such data, which included those relating to the dental cavities in addition to those inherent to the tumours and the organs at risk. Results all patients, irrespective of type of treatment, received an average of 60 to 70 grays in 30/35 sittings. The patients treated with IMRT showed higher variation in absorbed radiation dose than those treated with 3D-CRT. The alveolar encirclement allowed the assessment of the absorbed radiation dose, and consequently it also allowed to assess the individual surgical risk for osteonecrosis in patients with head and neck tumours who underwent radiography treatment. Conclusions the study of DVH allows the assessment of limit dose and the detection of the areas at greater risk for osteoradionecrosis before dental surgery. PMID:23285316

  10. Efficiency of Ipratropium Bromide and Albuterol Deposition in the Lung Delivered via a Soft Mist Inhaler or Chlorofluorocarbon Metered-Dose Inhaler.

    PubMed

    MacGregor, T R; ZuWallack, R; Rubano, V; Castles, M A; Dewberry, H; Ghafouri, M; Wood, C C

    2016-04-01

    The propellant-free Combivent Respimat Soft Mist Inhaler (CVT-R) was developed to replace the chlorofluorocarbon-propelled Combivent metered-dose inhaler (CVT-MDI). This steady-state pharmacokinetic (PK) substudy evaluated drug lung-delivery efficiency, using data from two phase III safety and efficacy trials. PK parameters were obtained from well-controlled population PK analyses. Area under the plasma concentration-time curve (AUC), maximum observed plasma concentration (C(max)), and minimum observed plasma concentration (C(min)) showed systemic exposure to ipratropium bromide and albuterol delivered via the CVT-R was proportional to ex-mouthpiece delivered dose. Although the labeled dose of ipratropium bromide in the CVT-R was half that in the CVT-MDI, the systemic exposure was comparable. No PK interaction for the ipratropium bromide and albuterol Respimat drug components was demonstrated. Ipratropium bromide alone resulted in similar exposure to the combination of ipratropium bromide and albuterol. These results show that CVT-R delivers drug more efficiently to the lung than CVT-MDI. PMID:26945929

  11. Efficiency of Ipratropium Bromide and Albuterol Deposition in the Lung Delivered via a Soft Mist Inhaler or Chlorofluorocarbon Metered-Dose Inhaler.

    PubMed

    MacGregor, T R; ZuWallack, R; Rubano, V; Castles, M A; Dewberry, H; Ghafouri, M; Wood, C C

    2016-04-01

    The propellant-free Combivent Respimat Soft Mist Inhaler (CVT-R) was developed to replace the chlorofluorocarbon-propelled Combivent metered-dose inhaler (CVT-MDI). This steady-state pharmacokinetic (PK) substudy evaluated drug lung-delivery efficiency, using data from two phase III safety and efficacy trials. PK parameters were obtained from well-controlled population PK analyses. Area under the plasma concentration-time curve (AUC), maximum observed plasma concentration (C(max)), and minimum observed plasma concentration (C(min)) showed systemic exposure to ipratropium bromide and albuterol delivered via the CVT-R was proportional to ex-mouthpiece delivered dose. Although the labeled dose of ipratropium bromide in the CVT-R was half that in the CVT-MDI, the systemic exposure was comparable. No PK interaction for the ipratropium bromide and albuterol Respimat drug components was demonstrated. Ipratropium bromide alone resulted in similar exposure to the combination of ipratropium bromide and albuterol. These results show that CVT-R delivers drug more efficiently to the lung than CVT-MDI.

  12. Measurement of absorbed dose-to-water for an HDR {sup 192}Ir source with ionization chambers in a sandwich setup

    SciTech Connect

    Araki, Fujio; Kouno, Tomohiro; Ohno, Takeshi; Kakei, Kiyotaka; Yoshiyama, Fumiaki; Kawamura, Shinji

    2013-09-15

    Purpose: In this study, a dedicated device for ion chamber measurements of absorbed dose-to-water for a Nucletron microSelectron-v2 HDR {sup 192}Ir brachytherapy source is presented. The device uses two ionization chambers in a so-called sandwich assembly. Using this setup and by taking the average reading of the two chambers, any dose error due to difficulties in absolute positioning (centering) of the source in between the chambers is cancelled to first order. The method's accuracy was examined by comparing measurements with absorbed dose-to-water determination based on the AAPM TG-43 protocol.Methods: The optimal source-to-chamber distance (SCD) for {sup 192}Ir dosimetry was determined from ion chamber measurements in a water phantom. The {sup 192}Ir source was sandwiched between two Exradin A1SL chambers (0.057 cm{sup 3}) at the optimal SCD separation. The measured ionization was converted to the absorbed dose-to-water using a {sup 60}Co calibration factor and a Monte Carlo-calculated beam quality conversion factor, k{sub Q}, for {sup 60}Co to {sup 192}Ir. An uncertainty estimate of the proposed method was determined based on reproducibility of measurements at different institutions for the same type of source.Results: The optimal distance for the A1SL chamber measurements was determined to be 5 cm from the {sup 192}Ir source center, considering the depth dependency of k{sub Q} for {sup 60}Co to {sup 192}Ir and the chamber positioning. The absorbed dose to water measured at (5 cm, 90°) on the transverse axis was 1.3% lower than TG-43 values and its reproducibility and overall uncertainty were 0.8% and 1.7%, respectively. The measurement doses at anisotropic points agreed within 1.5% with TG-43 values.Conclusions: The ion chamber measurement of absorbed dose-to-water with a sandwich method for the {sup 192}Ir source provides a more accurate, direct, and reference dose compared to the dose-to-water determination based on air-kerma strength in the TG-43 protocol

  13. SU-D-201-02: Prediction of Delivered Dose Based On a Joint Histogram of CT and FDG PET Images

    SciTech Connect

    Park, M; Choi, Y; Cho, A; Hwang, S; Cha, J; Lee, N; Yun, M

    2015-06-15

    Purpose: To investigate whether pre-treatment images can be used in predicting microsphere distribution in tumors. When intra-arterial radioembolization using Y90 microspheres was performed, the microspheres were often delivered non-uniformly within the tumor, which could lead to an inefficient therapy. Therefore, it is important to estimate the distribution of microspheres. Methods: Early arterial phase CT and FDG PET images were acquired for patients with primary liver cancer prior to radioembolization (RE) using Y90 microspheres. Tumor volume was delineated on CT images and fused with FDG PET images. From each voxel (3.9×3.9×3.3 mm3) in the tumor, the Hounsfield unit (HU) from the CT and SUV values from the FDG PET were harvested. We binned both HU and SUV into 11 bins and then calculated a normalized joint-histogram in an 11×11 array.Patients also underwent a post-treatment Y90 PET imaging. Radiation dose for the tumor was estimated using convolution of the Y90 distribution with a dose-point kernel. We also calculated a fraction of the tumor volume that received a radiation dose great than 100Gy. Results: Averaged over 40 patients, 55% of tumor volume received a dose greater than 100Gy (range : 1.1 – 100%). The width of the joint histogram was narrower for patients with a high dose. For patients with a low dose, the width was wider and a larger fraction of tumor volume had low HU. Conclusion: We have shown the pattern of joint histogram of the HU and SUV depends on delivered dose. The patterns can predict the efficacy of uniform intra-arterial delivery of Y90 microspheres.

  14. A graphite calorimeter for absolute measurements of absorbed dose to water: application in medium-energy x-ray filtered beams.

    PubMed

    Pinto, M; Pimpinella, M; Quini, M; D'Arienzo, M; Astefanoaei, I; Loreti, S; Guerra, A S

    2016-02-21

    The Italian National Institute of Ionizing Radiation Metrology (ENEA-INMRI) has designed and built a graphite calorimeter that, in a water phantom, has allowed the determination of the absorbed dose to water in medium-energy x-rays with generating voltages from 180 to 250 kV. The new standard is a miniaturized three-bodies calorimeter, with a disc-shaped core of 21 mm diameter and 2 mm thickness weighing 1.134 g, sealed in a PMMA waterproof envelope with air-evacuated gaps. The measured absorbed dose to graphite is converted into absorbed dose to water by means of an energy-dependent conversion factor obtained from Monte Carlo simulations. Heat-transfer correction factors were determined by FEM calculations. At a source-to-detector distance of 100 cm, a depth in water of 2 g cm(-2), and at a dose rate of about 0.15 Gy min(-1), results of calorimetric measurements of absorbed dose to water, D(w), were compared to experimental determinations, D wK, obtained via an ionization chamber calibrated in terms of air kerma, according to established dosimetry protocols. The combined standard uncertainty of D(w) and D(wK) were estimated as 1.9% and 1.7%, respectively. The two absorbed dose to water determinations were in agreement within 1%, well below the stated measurement uncertainties. Advancements are in progress to extend the measurement capability of the new in-water-phantom graphite calorimeter to other filtered medium-energy x-ray qualities and to reduce the D(w) uncertainty to around 1%. The new calorimeter represents the first implementation of in-water-phantom graphite calorimetry in the kilovoltage range and, allowing independent determinations of D(w), it will contribute to establish a robust system of absorbed dose to water primary standards for medium-energy x-ray beams. PMID:26841127

  15. Postprandial metabolic responses of serum calcium, parathyroid hormone and C-telopeptide of type I collagen to three doses of calcium delivered in milk.

    PubMed

    Kruger, Marlena C; von Hurst, Pamela R; Booth, Christine L; Kuhn-Sherlock, Barbara; Todd, Joanne M; Schollum, Linda M

    2014-01-01

    Acute doses of Ca rapidly increase serum Ca and reduce bone resorption concomitant with a reduction in serum parathyroid hormone (PTH) levels. The physiological response to a dose of Ca in milk and to a Ca salt may be different. The present study investigated Ca absorption patterns with increasing levels of fortification in milk, and the response to one dose of a Ca salt. A group of twenty-eight Asian women aged 20-45 years volunteered to attend the laboratory over several weeks. The fasted volunteers were randomised to one of three experimental drinks: 200 ml skimmed milk containing 250, 500 or 1000 mg Ca. A subgroup of seven volunteers also received a calcium gluconate/carbonate salt containing 1000 mg Ca in 200 ml water. Serial blood samples and urine were collected for 5 h from baseline. Different doses of Ca in milk resulted in a graded response in serum corrected Ca, PTH and C-telopeptide of type I collagen (CTx) but not ionised Ca. Serum Ca increased in response to all milk drinks and from 2 to 5 h the blood Ca levels were significantly different for the 250 and 1000 mg doses, as was the integrated response between the loads. The PTH response to the two higher doses was significantly more than following the 250 mg dose. The integrated response for CTx and urinary Ca between all three doses of Ca in milk was significantly different. A dose of Ca salt elicited a more immediate response reaching a plateau faster, and declining faster to baseline. Fortified milk is a safe matrix for delivering larger doses of Ca. PMID:25191614

  16. Direct measurement of absorbed dose to water in HDR {sup 192}Ir brachytherapy: Water calorimetry, ionization chamber, Gafchromic film, and TG-43

    SciTech Connect

    Sarfehnia, Arman; Kawrakow, Iwan; Seuntjens, Jan

    2010-04-15

    Purpose: Gafchromic film and ionometric calibration procedures for HDR {sup 192}Ir brachytherapy sources in terms of dose rate to water are presented and the experimental results are compared to the TG-43 protocol as well as with the absolute dose measurement results from a water calorimetry-based primary standard. Methods: EBT-1 Gafchromic films, an A1SL Exradin miniature Shonka thimble type chamber, and an SI HDR 1000 Plus well-type chamber (Standard Imaging, Inc., Middleton, WI) with an ADCL traceable S{sub k} calibration coefficient (following the AAPM TG-43 protocol) were used. The Farmer chamber and Gafchromic film measurements were performed directly in water. All results were compared to direct and absolute absorbed dose to water measurements from a 4 deg. C stagnant water calorimeter. Results: Based on water calorimetry, the authors measured the dose rate to water to be 361{+-}7 {mu}Gy/(h U) at a 55 mm source-to-detector separation. The dose rate normalized to air-kerma strength for all the techniques agree with the water calorimetry results to within 0.83%. The overall 1-sigma uncertainty on water calorimetry, ionization chamber, Gafchromic film, and TG-43 dose rate measurement amounts to 1.90%, 1.44%, 1.78%, and 2.50%, respectively. Conclusions: This work allows us to build a more realistic uncertainty estimate for absorbed dose to water determination using the TG-43 protocol. Furthermore, it provides the framework necessary for a shift from indirect HDR {sup 192}Ir brachytherapy dosimetry to a more accurate, direct, and absolute measurement of absorbed dose to water.

  17. SU-C-BRF-04: Delivered 4D Dose Calculation for Lung-VMAT Patients Using In- Treatment CBCT and LINAC Log Data

    SciTech Connect

    Saotome, N; Haga, A; Imae, T; Kida, S; Nakano, M; Yamashita, H; Nakagawa, K; Ohtomo, K

    2014-06-15

    Purpose: To verify the delivered four-dimensional (4D) dose distribution for the lung VMAT using in-treatment 4D cone-beam CT (CBCT) and LINAC log data. Methods: Three patients for lung stereotactic radiotherapy (SRT) were treated by single-arc volumetric modulated arc therapy (VMAT) created by SmartArc in Pinnacle v9.2 (Philips, USA).Kilovoltage (kV) projection images were acquired during VMAT delivery using the x-ray volumetric imager, XVI (Elekta, UK). LINAC log data were also recorded via iCom interface (Elekta, UK). Subsequently, the iCom data format was converted to Pinnacle data format, thereby allowing Pinnacle to read actual MLC positions, jaw positions, gantry angles and MUs. These parameters were categorized into four groups according to patient's respiratory phase. The patient respiratory phase was determined from kV-projection images by in-house phase recognizing software. By exporting these data back to Pinnacle, in-treatment dose distributions for each respiratory phase were obtained by combining calculated dose having a particular phase. The 4D CBCT were reconstructed by in-house program. The density in the structures on the CBCT was overridden by the average density in the corresponding structures on the planning CT for the dose calculation. The dose indexes, such as maximum, minimum, mean dose in the target were compared among the plan, in-treatment 3D calculation, and in-treatment 4D calculation. Results: The day-to-day variation of the delivered dose was observed for all three patients. The maximum difference was 5.9% for the minimum dose in the target. Difference for the mean dose was found to be small (1.1% at maximum). Conclusion: We have obtained in-treatment dose distribution for each of the different respiratory phases using in-treatment 4D CBCT and LINAC log data during lung VMAT delivery. Our result indicate a small but significant dose difference between the 3D and 4D calculations for the case of large target traveling.

  18. TH-A-19A-03: Impact of Proton Dose Calculation Method On Delivered Dose to Lung Tumors: Experiments in Thorax Phantom and Planning Study in Patient Cohort

    SciTech Connect

    Grassberger, C; Daartz, J; Dowdell, S; Ruggieri, T; Sharp, G; Paganetti, H

    2014-06-15

    Purpose: Evaluate Monte Carlo (MC) dose calculation and the prediction of the treatment planning system (TPS) in a lung phantom and compare them in a cohort of 20 lung patients treated with protons. Methods: A 2-dimensional array of ionization chambers was used to evaluate the dose across the target in a lung phantom. 20 lung cancer patients on clinical trials were re-simulated using a validated Monte Carlo toolkit (TOPAS) and compared to the TPS. Results: MC increases dose calculation accuracy in lung compared to the clinical TPS significantly and predicts the dose to the target in the phantom within ±2%: the average difference between measured and predicted dose in a plane through the center of the target is 5.6% for the TPS and 1.6% for MC. MC recalculations in patients show a mean dose to the clinical target volume on average 3.4% lower than the TPS, exceeding 5% for small fields. The lower dose correlates significantly with aperture size and the distance of the tumor to the chest wall (Spearman's p=0.0002/0.004). For large tumors MC also predicts consistently higher V{sub 5} and V{sub 10} to the normal lung, due to a wider lateral penumbra, which was also observed experimentally. Critical structures located distal to the target can show large deviations, though this effect is very patient-specific. Conclusion: Advanced dose calculation techniques, such as MC, would improve treatment quality in proton therapy for lung cancer by avoiding systematic overestimation of target dose and underestimation of dose to normal lung. This would increase the accuracy of the relationships between dose and effect, concerning tumor control as well as normal tissue toxicity. As the role of proton therapy in the treatment of lung cancer continues to be evaluated in clinical trials, this is of ever-increasing importance. This work was supported by National Cancer Institute Grant R01CA111590.

  19. A Monte Carlo study on the effect of the orbital bone to the radiation dose delivered to the eye lens

    NASA Astrophysics Data System (ADS)

    Stratis, Andreas; Zhang, Guozhi; Jacobs, Reinhilde; Bogaerts, Ria; Bosmans, Hilde

    2015-03-01

    The aim of this work was to investigate the influence of backscatter radiation from the orbital bone and the intraorbital fat on the eye lens dose in the dental CBCT energy range. To this end we conducted three different yet interrelated studies; A preliminary simulation study was conducted to examine the impact of a bony layer situated underneath a soft tissue layer on the amount of backscatter radiation. We compared the Percentage Depth Dose (PDD) curves in soft tissue with and without the bone layer and we estimated the depth in tissue where the decrease in backscatter caused by the presence of the bone is noticeable. In a supplementary study, an eye voxel phantom was designed with the DOSxyznrc code. Simulations were performed exposing the phantom at different x-ray energies sequentially in air, in fat tissue and in realistic anatomy with the incident beam perpendicular to the phantom. Finally, a virtual head phantom was implemented into a validated hybrid Monte Carlo (MC) framework to simulate a large Field of View protocol of a real CBCT scanner and examine the influence of scattered dose to the eye lens during the whole rotation of the paired tube-detector system. The results indicated an increase in the dose to the lens due to the fatty tissue in the surrounding anatomy. There is a noticeable dose reduction close to the bone-tissue interface which weakens with increasing distance from the interface, such that the impact of the orbital bone in the eye lens dose becomes small.

  20. Intraoperative Full-Dose of Partial Breast Irradiation with Electrons Delivered by Standard Linear Accelerators for Early Breast Cancer

    PubMed Central

    Barros, Alfredo Carlos S. D.; Hanna, Samir A.; Carvalho, Heloísa A.; Martella, Eduardo; Andrade, Felipe Eduardo M.; Piato, José Roberto M.; Bevilacqua, José Luiz B.

    2014-01-01

    Purpose. To assess feasibility, efficacy, toxicity, and cosmetic results of intraoperative radiotherapy (IORT) with electrons delivered by standard linear accelerators (Linacs) during breast conserving surgeries for early infiltrating breast cancer (BC) treatment. Materials and Methods. A total of 152 patients with invasive ductal carcinoma (T ≤ 3.0 cm) at low risk for local relapses were treated. All had unicentric lesions by imaging methods and negative sentinel node. After a wide local excision, 21 Gy were delivered on the parenchyma target volume with electron beams. Local recurrences (LR), survival, toxicity, and cosmetic outcomes were analyzed. Results. The median age was 58.3 years (range 40–85); median follow-up was 50.7 months (range 12–101.5). There were 5 cases with LR, 2 cases with distant metastases, and 2 cases with deaths related to BC. The cumulative incidence rates of LR, distant metastases, and BC death were 3.2%, 1.5%, and 1.5%, respectively. Complications were rare, and the cosmetic results were excellent or good in most of the patients. Conclusions. IORT with electrons delivered by standard Linacs is feasible, efficient, and well tolerated and seems to be beneficial for selected patients with early infiltrating BC. PMID:25587452

  1. SU-E-T-515: Field-In-Field Compensation Technique Using Multi-Leaf Collimator to Deliver Total Body Irradiation (TBI) Dose

    SciTech Connect

    Lakeman, T; Wang, IZ

    2014-06-01

    Purpose: Total body irradiation (TBI) uses large parallel-opposed radiation fields to suppress the patient's immune system and eradicate the residual cancer cells in preparation of recipient for bone marrow transplant. The manual placement of lead compensators has been used conventionally to compensate for the varying thickness through the entire body in large-field TBI. The goal of this study is to pursue utilizing the modern field-in-field (FIF) technique with the multi-leaf collimator (MLC) to more accurately and efficiently deliver dose to patients in need of TBI. Method: Treatment plans utilizing the FIF technique to deliver a total body dose were created retrospectively for patients for whom CT data had been previously acquired. Treatment fields include one pair of opposed open large fields (collimator=45°) with a specific weighting and a succession of smaller fields (collimator=90°) each with their own weighting. The smaller fields are shaped by moving MLC to block the sections of the patient which have already received close to 100% of the prescribed dose. The weighting factors for each of these fields were calculated using the attenuation coefficient of the initial lead compensators and the separation of the patient in different positions in the axial plane. Results: Dose-volume histograms (DVH) were calculated for evaluating the FIF compensation technique. The maximum body doses calculated from the DVH were reduced from the non-compensated 179.3% to 148.2% in the FIF plans, indicating a more uniform dose with the FIF compensation. All calculated monitor units were well within clinically acceptable limits and exceeded those of the original lead compensation plan by less than 50 MU (only ~1.1% increase). Conclusion: MLC FIF technique for TBI will not significantly increase the beam on time while it can substantially reduce the compensator setup time and the potential risk of errors in manually placing lead compensators.

  2. Determination of absorbed dose to water around a clinical HDR {sup 192}Ir source using LiF:Mg,Ti TLDs demonstrates an LET dependence of detector response

    SciTech Connect

    Carlsson Tedgren, Aasa; Elia, Rouba; Hedtjaern, Haakan; Olsson, Sara; Alm Carlsson, Gudrun

    2012-02-15

    Purpose: Experimental radiation dosimetry with thermoluminescent dosimeters (TLDs), calibrated in a {sup 60}Co or megavoltage (MV) photon beam, is recommended by AAPM TG-43U1for verification of Monte Carlo calculated absorbed doses around brachytherapy sources. However, it has been shown by Carlsson Tedgren et al.[Med. Phys. 38, 5539-5550 (2011)] that for TLDs of LiF:Mg,Ti, detector response was 4% higher in a {sup 137}Cs beam than in a {sup 60}Co one. The aim of this work was to investigate if similar over-response exists when measuring absorbed dose to water around {sup 192}Ir sources, using LiF:Mg,Ti dosimeters calibrated in a 6 MV photon beam. Methods: LiF dosimeters were calibrated to measure absorbed dose to water in a 6 MV photon beam and used to measure absorbed dose to water at distances of 3, 5, and 7 cm from a clinical high dose rate (HDR) {sup 192}Ir source in a polymethylmethacrylate (PMMA) phantom. Measured values were compared to values of absorbed dose to water calculated using a treatment planning system (TPS) including corrections for the difference in energy absorption properties between calibration quality and the quality in the users'{sup 192}Ir beam and for the use of a PMMA phantom instead of the water phantom underlying dose calculations in the TPS. Results: Measured absorbed doses to water around the {sup 192}Ir source were overestimated by 5% compared to those calculated by the TPS. Corresponding absorbed doses to water measured in a previous work with lithium formate electron paramagnetic resonance (EPR) dosimeters by Antonovic et al. [Med. Phys. 36, 2236-2247 (2009)], using the same irradiation setup and calibration procedure as in this work, were 2% lower than those calculated by the TPS. The results obtained in the measurements in this work and those obtained using the EPR lithium formate dosimeters were, within the expanded (k = 2) uncertainty, in agreement with the values derived by the TPS. The discrepancy between the results using

  3. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetité, Bahia, Brazil

    NASA Astrophysics Data System (ADS)

    Pereira, Wagner de S.; Kelecom, Alphonse; Py Júnior, Delcy de Azevedo

    2008-08-01

    The uranium mining at Caetité (Uranium Concentrate Unit—URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5×103 μGy y-1 has been used. The derived absorbed dose rate calculated for Tilapia was 2.51×100 μGy y-1, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota.

  4. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetite, Bahia, Brazil

    SciTech Connect

    Pereira, Wagner de S; Kelecom, Alphonse

    2008-08-07

    The uranium mining at Caetite (Uranium Concentrate Unit--URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5x10{sup 3} {mu}Gy y{sup -1} has been used. The derived absorbed dose rate calculated for Tilapia was 2.51x10{sup 0} {mu}Gy y{sup -1}, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota.

  5. A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for (99m)Tc-hynic-Tyr(3)-octreotide Imaging.

    PubMed

    Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed Rasoul; Parach, Ali Asghar; Ghorbani, Mahdi; Asl, Ruhollah Ghahraman

    2016-01-01

    Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of (99m)Tc-hydrazinonicotinamide (hynic)-Tyr(3)-octreotide as a SPECT radiotracer. (99m)Tc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of (99m)hynic-Tyr(3)-octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results.

  6. Measurement of absorbed dose to water around an electronic brachytherapy source. Comparison of two dosimetry systems: lithium formate EPR dosimeters and radiochromic EBT2 film

    NASA Astrophysics Data System (ADS)

    Adolfsson, Emelie; White, Shane; Landry, Guillaume; Lund, Eva; Gustafsson, Håkan; Verhaegen, Frank; Reniers, Brigitte; Carlsson Tedgren, Åsa; Alm Carlsson, Gudrun

    2015-05-01

    Interest in high dose rate (HDR) electronic brachytherapy operating at 50 kV is increasing. For quality assurance it is important to identify dosimetry systems that can measure the absorbed doses in absolute terms which is difficult in this energy region. In this work a comparison is made between two dosimetry systems, EPR lithium formate dosimeters and radiochromic EBT2 film. Both types of dosimeters were irradiated simultaneously in a PMMA phantom using the Axxent EBS. Absorbed dose to water was determined at distances of 10 mm, 30 mm and 50 mm from the EBS. Results were traceable to different primary standards as regards to absorbed dose to water (EPR) and air kerma (EBT2). Monte Carlo simulations were used in absolute terms as a third estimate of absorbed dose to water. Agreement within the estimated expanded (k = 2) uncertainties (5% (EPR), 7% (EBT2)) was found between the results at 30 mm and 50 mm from the x-ray source. The same result was obtained in 4 repetitions of irradiation, indicating high precision in the measurements with both systems. At all distances, agreement between EPR and Monte Carlo simulations was shown as was also the case for the film measurements at 30mm and 50mm. At 10mm the geometry for the film measurements caused too large uncertainty in measured values depending on the exact position (within sub-mm distances) of the EBS and the 10 mm film results were exculded from comparison. This work has demonstrated good performance of the lithium formate EPR dosimetry system in accordance with earlier experiments at higher photon energies (192Ir HDR brachytherapy). It was also highlighted that there might be issues regarding the energy dependence and intrinsic efficiency of the EBT2 film that need to be considered for measurements using low energy sources.

  7. A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for (99m)Tc-hynic-Tyr(3)-octreotide Imaging.

    PubMed

    Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed Rasoul; Parach, Ali Asghar; Ghorbani, Mahdi; Asl, Ruhollah Ghahraman

    2016-01-01

    Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of (99m)Tc-hydrazinonicotinamide (hynic)-Tyr(3)-octreotide as a SPECT radiotracer. (99m)Tc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of (99m)hynic-Tyr(3)-octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results. PMID:27134562

  8. A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for 99mTc-hynic-Tyr3-octreotide Imaging

    PubMed Central

    Momennezhad, Mehdi; Nasseri, Shahrokh; Zakavi, Seyed Rasoul; Parach, Ali Asghar; Ghorbani, Mahdi; Asl, Ruhollah Ghahraman

    2016-01-01

    Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of 99mTc-hydrazinonicotinamide (hynic)-Tyr3-octreotide as a SPECT radiotracer. 99mTc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of 99mhynic-Tyr3-octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results. PMID:27134562

  9. SU-E-J-154: Deformable Image Registration Based Delivered Dose Estimation for Head and Neck Radiotherapy

    SciTech Connect

    Kumarasiri, A; Liu, C; Chetvertkov, M; Gordon, J; Siddiqui, F; Chetty, I; Kim, J

    2014-06-01

    Purpose: To estimate the accumulated dose to targets and organs at risk (OAR) for head and neck (H'N) radiotherapy using 3 deformable image registration (DIR) algorithms. Methods: Five H'N patients, who had daily CBCTs taken during the course of treatment, were retrospectively studied. All plans had 5 mm CTV-to-PTV expansions. To overcome the small field of view (FOV) limitations and HU uncertainties of CBCTs, CT images were deformably registered using a parameter-optimized B-spline DIR algorithm (Elastix, elastix.isi.uu.nl) and resampled onto each CBCT with a 4 cm uniform FOV expansion. The dose of the day was calculated on these resampled CT images. Calculated daily dose matrices were warped and accumulated to the planning CT using 3 DIR algorithms; SmartAdapt (Eclipse/Varian), Velocity (Velocity Medical Solutions), and Elastix. Dosimetric indices for targets and OARs were determined from the DVHs and compared with corresponding planned quantities. Results: The cumulative dose deviation was less than 2%, on average, for PTVs from the corresponding plan dose, for all algorithms/patients. However, the parotids show as much as a 37% deviation from the intended dose, possibly due to significant patient weight loss during the first 3 weeks of treatment (15.3 lbs in this case). The mean(±SD) cumulative dose deviations of the 5 patients estimated using the 3 algorithms (SmartAdapt, Velocity, and Elastix) were (0.8±0.9%, 0.5±0.9%, 0.6±1.3%) for PTVs, (1.6±1.9%, 1.4±2.0%, 1.7±1.9%) for GTVs, (10.4±12.1%, 10.7±10.6%, 6.5±10.1%) for parotid glands, and (4.5±4.6%, 3.4±5.7%, 3.9±5.7%) for mucosa, respectively. The differences among the three DIR algorithms in the estimated cumulative mean doses (1SD (in Gy)) were: 0.1 for PTVs, 0.1 for GTVs, 1.9 for parotid glands, and 0.4 for mucosa. Conclusion: Results of this study are suggestive that more frequent plan adaptation for organs, such as the parotid glands, might be beneficial during the course of H'N RT. This

  10. High-dose-rate brachytherapy delivered in two fractions as monotherapy for low-risk prostate cancer

    PubMed Central

    Alwers, Elizabeth; Cifuentes, Javier; Bobadilla, Ivan; Torres, Felipe; Arbelaez, Juan; Gaitan, Armando; Cortes, Helber; Acevedo, Yenny; Quintero, Paulo; Vasquez, Jaider

    2015-01-01

    Purpose High-dose-rate (HDR) brachytherapy has been accepted as an effective and safe method to treat prostate cancer. The aim of this study was to describe acute toxicity following HDR brachytherapy to the prostate, and to examine the association between dosimetric parameters and urinary toxicity in low-risk prostate cancer patients. Material and methods Patients with low-risk prostate cancer were given HDR brachytherapy as monotherapy in two 12.5 Gy fractions. Planning objectives for the planning target volume (PTV) were V100% ≥ 90% and V150% ≤ 35%. Planning objectives for organs at risk were V75% ≤ 1 cc for the bladder, rectum and perineum, and V125% ≤ 1 cc for the urethra. Toxicity was assessed three months after treatment using the Common Terminology Criteria for Adverse Events. Results Seventy-three patients were included in the analysis. Thirty-three patients (45%) reported having any type of toxicity in the three months following HDR brachytherapy. Most toxicity cases (26%) were grade 1 urinary toxicity. Mean coverage index was 0.89 and mean V100 was 88.85. Doses administered to the urethra were associated with urinary toxicity. Patients who received more than 111.3% of the prescribed dose in 1 cc of the urethra were four times more likely to have urinary toxicity compared to patients receiving less than 111.3% (OR = 4.71, 95% CI: 1.43-15.6; p = 0.011). Conclusions High-dose-rate brachytherapy administered as monotherapy for prostate cancer proved to be a safe alternative treatment for patients with low-risk prostate cancer. Urinary toxicity was associated with the dose administered to 1 cc and 0.1 cc of the urethra and was remarkably inferior to the reported toxicity in similar studies. PMID:25829931

  11. Role of shielding in modulating the effects of solar particle events: Monte Carlo calculation of absorbed dose and DNA complex lesions in different organs

    NASA Astrophysics Data System (ADS)

    Ballarini, F.; Biaggi, M.; De Biaggi, L.; Ferrari, A.; Ottolenghi, A.; Panzarasa, A.; Paretzke, H. G.; Pelliccioni, M.; Sala, P.; Scannicchio, D.; Zankl, M.

    2004-01-01

    Distributions of absorbed dose and DNA clustered damage yields in various organs and tissues following the October 1989 solar particle event (SPE) were calculated by coupling the FLUKA Monte Carlo transport code with two anthropomorphic phantoms (a mathematical model and a voxel model), with the main aim of quantifying the role of the shielding features in modulating organ doses. The phantoms, which were assumed to be in deep space, were inserted into a shielding box of variable thickness and material and were irradiated with the proton spectra of the October 1989 event. Average numbers of DNA lesions per cell in different organs were calculated by adopting a technique already tested in previous works, consisting of integrating into "condensed-history" Monte Carlo transport codes - such as FLUKA - yields of radiobiological damage, either calculated with "event-by-event" track structure simulations, or taken from experimental works available in the literature. More specifically, the yields of "Complex Lesions" (or "CL", defined and calculated as a clustered DNA damage in a previous work) per unit dose and DNA mass (CL Gy -1 Da -1) due to the various beam components, including those derived from nuclear interactions with the shielding and the human body, were integrated in FLUKA. This provided spatial distributions of CL/cell yields in different organs, as well as distributions of absorbed doses. The contributions of primary protons and secondary hadrons were calculated separately, and the simulations were repeated for values of Al shielding thickness ranging between 1 and 20 g/cm 2. Slight differences were found between the two phantom types. Skin and eye lenses were found to receive larger doses with respect to internal organs; however, shielding was more effective for skin and lenses. Secondary particles arising from nuclear interactions were found to have a minor role, although their relative contribution was found to be larger for the Complex Lesions than for

  12. Low-dose oxytocin delivered intranasally with Breath Powered device affects social-cognitive behavior: a randomized four-way crossover trial with nasal cavity dimension assessment

    PubMed Central

    Quintana, D S; Westlye, L T; Rustan, Ø G; Tesli, N; Poppy, C L; Smevik, H; Tesli, M; Røine, M; Mahmoud, R A; Smerud, K T; Djupesland, P G; Andreassen, O A

    2015-01-01

    Despite the promise of intranasal oxytocin (OT) for modulating social behavior, recent work has provided mixed results. This may relate to suboptimal drug deposition achieved with conventional nasal sprays, inter-individual differences in nasal physiology and a poor understanding of how intranasal OT is delivered to the brain in humans. Delivering OT using a novel ‘Breath Powered' nasal device previously shown to enhance deposition in intranasal sites targeted for nose-to-brain transport, we evaluated dose-dependent effects on social cognition, compared response with intravenous (IV) administration of OT, and assessed nasal cavity dimensions using acoustic rhinometry. We adopted a randomized, double-blind, double-dummy, crossover design, with 16 healthy male adults completing four single-dose treatments (intranasal 8 IU (international units) or 24 IU OT, 1 IU OT IV and placebo). The primary outcome was social cognition measured by emotional ratings of facial images. Secondary outcomes included the pharmacokinetics of OT, vasopressin and cortisol in blood and the association between nasal cavity dimensions and emotional ratings. Despite the fact that all the treatments produced similar plasma OT increases compared with placebo, there was a main effect of treatment on anger ratings of emotionally ambiguous faces. Pairwise comparisons revealed decreased ratings after 8 IU OT in comparison to both placebo and 24 IU OT. In addition, there was an inverse relationship between nasal valve dimensions and anger ratings of ambiguous faces after 8-IU OT treatment. These findings provide support for a direct nose-to-brain effect, independent of blood absorption, of low-dose OT delivered from a Breath Powered device. PMID:26171983

  13. Low-dose oxytocin delivered intranasally with Breath Powered device affects social-cognitive behavior: a randomized four-way crossover trial with nasal cavity dimension assessment.

    PubMed

    Quintana, D S; Westlye, L T; Rustan, Ø G; Tesli, N; Poppy, C L; Smevik, H; Tesli, M; Røine, M; Mahmoud, R A; Smerud, K T; Djupesland, P G; Andreassen, O A

    2015-01-01

    Despite the promise of intranasal oxytocin (OT) for modulating social behavior, recent work has provided mixed results. This may relate to suboptimal drug deposition achieved with conventional nasal sprays, inter-individual differences in nasal physiology and a poor understanding of how intranasal OT is delivered to the brain in humans. Delivering OT using a novel 'Breath Powered' nasal device previously shown to enhance deposition in intranasal sites targeted for nose-to-brain transport, we evaluated dose-dependent effects on social cognition, compared response with intravenous (IV) administration of OT, and assessed nasal cavity dimensions using acoustic rhinometry. We adopted a randomized, double-blind, double-dummy, crossover design, with 16 healthy male adults completing four single-dose treatments (intranasal 8 IU (international units) or 24 IU OT, 1 IU OT IV and placebo). The primary outcome was social cognition measured by emotional ratings of facial images. Secondary outcomes included the pharmacokinetics of OT, vasopressin and cortisol in blood and the association between nasal cavity dimensions and emotional ratings. Despite the fact that all the treatments produced similar plasma OT increases compared with placebo, there was a main effect of treatment on anger ratings of emotionally ambiguous faces. Pairwise comparisons revealed decreased ratings after 8 IU OT in comparison to both placebo and 24 IU OT. In addition, there was an inverse relationship between nasal valve dimensions and anger ratings of ambiguous faces after 8-IU OT treatment. These findings provide support for a direct nose-to-brain effect, independent of blood absorption, of low-dose OT delivered from a Breath Powered device. PMID:26171983

  14. Comparison of the action spectra and relative DNA absorbance spectra of microorganisms: information important for the determination of germicidal fluence (UV dose) in an ultraviolet disinfection of water.

    PubMed

    Chen, Ren Zhuo; Craik, Stephen A; Bolton, James R

    2009-12-01

    The action spectra of Bacillus subtilis spores (ATCC6633) and Salmonella typhimurium LT2 were characterized using physical radiometry for irradiance measurements and a multiple target model to interpret the inactivation kinetics. The observed action spectrum of B. subtilis spores deviated significantly from the relative absorbance spectrum of the DNA purified from the spores, but matched quite well with the relative absorbance spectrum of decoated spores. The action spectrum of B. subtilis spores determined in this study was statistically different from those reported in previous studies. On the other hand, the action spectrum of S. typhimurium bacteria matched quite well with the relative absorbance spectrum of DNA extracted from vegetative cells, except in the region below 240nm. It is concluded that the common use of the relative DNA absorbance spectrum as a surrogate for the germicidal action spectrum can result in systematic errors when evaluating the performance of a polychromatic UV light reactors using bioassays. For example, if the weighted germicidal fluence (UV dose) calculated using the relative DNA absorbance spectrum as the germicidal weighting factor is found to be 40mJcm(-2) for a medium pressure lamp UV reactor, that calculated using the relative action spectrum of B. subtilis spores, as determined in this study, would be 66mJcm(-2). PMID:19762061

  15. Comparison of the action spectra and relative DNA absorbance spectra of microorganisms: information important for the determination of germicidal fluence (UV dose) in an ultraviolet disinfection of water.

    PubMed

    Chen, Ren Zhuo; Craik, Stephen A; Bolton, James R

    2009-12-01

    The action spectra of Bacillus subtilis spores (ATCC6633) and Salmonella typhimurium LT2 were characterized using physical radiometry for irradiance measurements and a multiple target model to interpret the inactivation kinetics. The observed action spectrum of B. subtilis spores deviated significantly from the relative absorbance spectrum of the DNA purified from the spores, but matched quite well with the relative absorbance spectrum of decoated spores. The action spectrum of B. subtilis spores determined in this study was statistically different from those reported in previous studies. On the other hand, the action spectrum of S. typhimurium bacteria matched quite well with the relative absorbance spectrum of DNA extracted from vegetative cells, except in the region below 240nm. It is concluded that the common use of the relative DNA absorbance spectrum as a surrogate for the germicidal action spectrum can result in systematic errors when evaluating the performance of a polychromatic UV light reactors using bioassays. For example, if the weighted germicidal fluence (UV dose) calculated using the relative DNA absorbance spectrum as the germicidal weighting factor is found to be 40mJcm(-2) for a medium pressure lamp UV reactor, that calculated using the relative action spectrum of B. subtilis spores, as determined in this study, would be 66mJcm(-2).

  16. Ion chamber absorbed dose calibration coefficients, N{sub D,w}, measured at ADCLs: Distribution analysis and stability

    SciTech Connect

    Muir, B. R.

    2015-04-15

    Purpose: To analyze absorbed dose calibration coefficients, N{sub D,w}, measured at accredited dosimetry calibration laboratories (ADCLs) for client ionization chambers to study (i) variability among N{sub D,w} coefficients for chambers of the same type calibrated at each ADCL to investigate ion chamber volume fluctuations and chamber manufacturing tolerances; (ii) equivalency of ion chamber calibration coefficients measured at different ADCLs by intercomparing N{sub D,w} coefficients for chambers of the same type; and (iii) the long-term stability of N{sub D,w} coefficients for different chamber types by investigating repeated chamber calibrations. Methods: Large samples of N{sub D,w} coefficients for several chamber types measured over the time period between 1998 and 2014 were obtained from the three ADCLs operating in the United States. These are analyzed using various graphical and numerical statistical tests for the four chamber types with the largest samples of calibration coefficients to investigate (i) and (ii) above. Ratios of calibration coefficients for the same chamber, typically obtained two years apart, are calculated to investigate (iii) above and chambers with standard deviations of old/new ratios less than 0.3% meet stability requirements for accurate reference dosimetry recommended in dosimetry protocols. Results: It is found that N{sub D,w} coefficients for a given chamber type compared among different ADCLs may arise from differing probability distributions potentially due to slight differences in calibration procedures and/or the transfer of the primary standard. However, average N{sub D,w} coefficients from different ADCLs for given chamber types are very close with percent differences generally less than 0.2% for Farmer-type chambers and are well within reported uncertainties. Conclusions: The close agreement among calibrations performed at different ADCLs reaffirms the Calibration Laboratory Accreditation Subcommittee process of ensuring

  17. Estimation of absorbed radiation dose rates in wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi nuclear power plant accident.

    PubMed

    Kubota, Yoshihisa; Takahashi, Hiroyuki; Watanabe, Yoshito; Fuma, Shoichi; Kawaguchi, Isao; Aoki, Masanari; Kubota, Masahide; Furuhata, Yoshiaki; Shigemura, Yusaku; Yamada, Fumio; Ishikawa, Takahiro; Obara, Satoshi; Yoshida, Satoshi

    2015-04-01

    The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium ((134)Cs and (137)Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 μGy h(-1) (1.2 mGy d(-1)), even 3 years after

  18. Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

    SciTech Connect

    Shtejer, K.; Arruda-Neto, J. D. T.; Rodrigues, T. E.; Schulte, R.; Wroe, A.; Menezes, M. O. de; Moralles, M.

    2008-08-11

    Proton induced non-elastic nuclear reactions play an important role in the dose distribution of clinically used proton beams as they deposit dose of high biological effectiveness both within the primary beam path as well as outside the beam to untargeted tissues. Non-elastic nuclear reactions can be evaluated using transport codes based on the Monte Carlo method. In this work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit, which are currently the most widely used Monte Carlo programs for proton radiation transport simulations in medical physics, to study the contribution of non-elastic nuclear interactions to the absorbed dose of proton beams in the therapeutic energy range. The impact of different available theoretical models to address the nuclear reaction process was investigated. The contribution of secondary particles from non-elastic nuclear reactions was calculated in three materials relevant in radiotherapy applications: water, PMMA and A150. The results evidence that there are differences in the calculated contribution of the secondary particles heavier than protons to the absorbed dose, with different approaches to model the nuclear reactions. The MCNPX calculation give rise to a larger contribution of d, t, {alpha}{sup 3}He to the total dose compared to the GEANT4 physical models chosen in this work.

  19. KEY COMPARISON: Comparison of the standards for absorbed dose to water of the ENEA-INMRI (Italy) and the BIPM for 60Co γ rays

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Allisy-Roberts, P. J.; Burns, D. T.; Guerra, A. S.; Laitano, R. F.; Pimpinella, M.

    2010-01-01

    A comparison of the standards for absorbed dose to water of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of the Ente per le Nuove Tecnologie, l'Energia e l'Ambiente, Italy (ENEA-INMRI), and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co gamma radiation under the auspices of the key comparison BIPM.RI(I)-K4. The comparison result, based on the calibration coefficients for three transfer standards and expressed as a ratio of the ENEA and the BIPM standards for absorbed dose to water, is 0.9999 (0.0044). The present 2007 result replaces the earlier ENEA value in this key comparison. The degrees of equivalence between the ENEA and the other participants in this comparison have been calculated and the results are given in the form of a matrix for the ten national metrology institutes (NMIs) that have published results in this ongoing comparison for absorbed dose to water. A graphical presentation is also given. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  20. Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

    SciTech Connect

    Power, S.; Mirza, M.; Thakorlal, A.; Ganai, B.; Gavagan, L. D.; Given, M. F.; Lee, M. J.

    2015-06-15

    PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

  1. Cone Beam CT vs. Fan Beam CT: A Comparison of Image Quality and Dose Delivered Between Two Differing CT Imaging Modalities

    PubMed Central

    Weidlich, Georg A.

    2016-01-01

    A comparison of image quality and dose delivered between two differing computed tomography (CT) imaging modalities—fan beam and cone beam—was performed. A literature review of quantitative analyses for various image quality aspects such as uniformity, signal-to-noise ratio, artifact presence, spatial resolution, modulation transfer function (MTF), and low contrast resolution was generated. With these aspects quantified, cone beam computed tomography (CBCT) shows a superior spatial resolution to that of fan beam, while fan beam shows a greater ability to produce clear and anatomically correct images with better soft tissue differentiation. The results indicate that fan beam CT produces superior images to that of on-board imaging (OBI) cone beam CT systems, while providing a considerably less dose to the patient. PMID:27752404

  2. Treatment of acute severe asthma with inhaled albuterol delivered via jet nebulizer, metered dose inhaler with spacer, or dry powder.

    PubMed

    Raimondi, A C; Schottlender, J; Lombardi, D; Molfino, N A

    1997-07-01

    Despite the increasing use of dry powder formulations in the ambulatory setting, there is a paucity of information on the efficacy of this therapeutic modality to treat acute severe asthma. In addition, studies that compared wet nebulization vs metered dose inhalers formulated with chlorofluorocarbon (CFCMDI) attached to holding chambers have yielded discrepant results. Thus, it is unclear which of the three delivery systems would elicit a superior bronchodilator response, particularly in patients with life-threatening asthma. In a prospective, randomized open design, we studied the response to inhaled albuterol (salbutamol) in 27 adult asthmatics presenting to the emergency department (ED) with an FEV1 <30% predicted. Subjects were treated with one of the following regimens (nine subjects in each group): group A, mean (SD) baseline FEV1 of 0.7 (0.2) L, received albuterol solution, 5 mg, via a nebulizer (Puritan-Bennett Raindrop; Lawrenceville, Ga) impelled with oxygen (O2) at 8 L/min; group B, baseline FEV1 of 0.6 (0.15) L, received albuterol, 400 microg, via a CFCMDI attached to a 145-mL valved aerosol holding chamber (Aerochamber; Trudell Medical; London, ON); and group C, baseline FEV1 of 0.6 (0.17) L, received albuterol powder, 400 microg, by another means (Rotahaler; Glaxo; Research Triangle Park, NC). All groups received the respective treatments on arrival in the ED, every 30 min during the first 2 h, and then hourly until the sixth hour. Clinical parameters and FEV1 were recorded on ED admission and 15 min after each dose of albuterol. At the time of ED admission, all patients also received continuous O2 and one dose of I.V. steroids (dexamethasone, 8 mg). The total dose of inhaled albuterol administered during the 6-h treatment was 45 mg of nebulized solution in group A and 3,600 microg of albuterol aerosol and dry powder in groups B and C, respectively. No significant differences were found in the population demographics, baseline FEV1, and arterial

  3. Calculated and TLD-based absorbed dose estimates for I-131-labeled 3F8 monoclonal antibody in a human neuroblastoma xenograft nude mouse model.

    PubMed

    Ugur, O; Scott, A M; Kostakoglu, L; Hui, T E; Masterson, M E; Febo, R; Sgouros, G; Rosa, E; Mehta, B M; Fisher, D R

    1995-01-01

    Preclinical evaluation of the therapeutic potential of radiolabeled antibodies is commonly performed in a xenografted nude mouse model. To assess therapeutic efficacy it is important to estimate the absorbed dose to the tumor and normal tissues of the nude mouse. The current study was designed to accurately measure radiation does to human neuroblastoma xenografts and normal organs in nude mice treated with I-131-labeled 3F8 monoclonal antibody (MoAb) against disialoganglioside GD2 antigen. Absorbed dose estimates were obtained using two different approaches: (1) measurement with teflon-imbedded CaSO4:Dy mini-thermoluminescent dosimeters (TLDs) and (2) calculations using mouse S-factors. The calculated total dose to tumor one week after i.v. injection of the 50 microCi I-131-3F8 MoAb was 604 cGy. The corresponding decay corrected and not corrected TLD measurements were 109 +/- 9 and 48.7 +/- 3.4 cGy respectively. The calculated to TLD-derived dose ratios for tumor ranged from 6.1 at 24 h to 5.5 at 1 week. The light output fading rate was found to depend upon the tissue type within which the TLDs were implanted. The decay rate in tumor, muscle, subcutaneous tissue and in vitro, were 9.5, 5.0, 3.7 and 0.67% per day, respectively. We have demonstrated that the type of tissue in which the TLD was implanted strongly influenced the in vivo decay of light output. Even with decay correction, a significant discrepancy was observed between MIRD-based calculated and CaSO4:Dy mini-TLD measured absorbed doses. Batch dependence, pH of the tumor or other variables associated with TLDs which are not as yet well known may account for this discrepancy.

  4. Comparison of film measurements and Monte Carlo simulations of dose delivered with very high-energy electron beams in a polystyrene phantom

    SciTech Connect

    Bazalova-Carter, Magdalena; Liu, Michael; Palma, Bianey; Koong, Albert C.; Maxim, Peter G. E-mail: BWLoo@Stanford.edu; Loo, Billy W. E-mail: BWLoo@Stanford.edu; Dunning, Michael; McCormick, Doug; Hemsing, Erik; Nelson, Janice; Jobe, Keith; Colby, Eric; Tantawi, Sami; Dolgashev, Valery

    2015-04-15

    Purpose: To measure radiation dose in a water-equivalent medium from very high-energy electron (VHEE) beams and make comparisons to Monte Carlo (MC) simulation results. Methods: Dose in a polystyrene phantom delivered by an experimental VHEE beam line was measured with Gafchromic films for three 50 MeV and two 70 MeV Gaussian beams of 4.0–6.9 mm FWHM and compared to corresponding MC-simulated dose distributions. MC dose in the polystyrene phantom was calculated with the EGSnrc/BEAMnrc and DOSXYZnrc codes based on the experimental setup. Additionally, the effect of 2% beam energy measurement uncertainty and possible non-zero beam angular spread on MC dose distributions was evaluated. Results: MC simulated percentage depth dose (PDD) curves agreed with measurements within 4% for all beam sizes at both 50 and 70 MeV VHEE beams. Central axis PDD at 8 cm depth ranged from 14% to 19% for the 5.4–6.9 mm 50 MeV beams and it ranged from 14% to 18% for the 4.0–4.5 mm 70 MeV beams. MC simulated relative beam profiles of regularly shaped Gaussian beams evaluated at depths of 0.64 to 7.46 cm agreed with measurements to within 5%. A 2% beam energy uncertainty and 0.286° beam angular spread corresponded to a maximum 3.0% and 3.8% difference in depth dose curves of the 50 and 70 MeV electron beams, respectively. Absolute dose differences between MC simulations and film measurements of regularly shaped Gaussian beams were between 10% and 42%. Conclusions: The authors demonstrate that relative dose distributions for VHEE beams of 50–70 MeV can be measured with Gafchromic films and modeled with Monte Carlo simulations to an accuracy of 5%. The reported absolute dose differences likely caused by imperfect beam steering and subsequent charge loss revealed the importance of accurate VHEE beam control and diagnostics.

  5. Two doses of bovine viral diarrhea virus DNA vaccine delivered by electroporation induce long-term protective immune responses.

    PubMed

    van Drunen Littel-van den Hurk, Sylvia; Lawman, Zoe; Snider, Marlene; Wilson, Don; van den Hurk, Jan V; Ellefsen, Barry; Hannaman, Drew

    2013-02-01

    Bovine viral diarrhea virus (BVDV) is a pathogen of major importance in cattle, so there is a need for new effective vaccines. DNA vaccines induce balanced immune responses and are relatively inexpensive and thus promising for both human and veterinary applications. In this study, newborn calves with maternal antibodies were vaccinated intramuscularly (i.m.) with a BVDV E2 DNA vaccine with the TriGrid Delivery System for i.m. delivery (TDS-IM). Two doses of this vaccine spaced 6 or 12 weeks apart were sufficient to induce significant virus-neutralizing antibody titers, numbers of activated T cells, and reduction in viral shedding and clinical presentations after BVDV-2 challenge. In contrast to the placebo-treated animals, the vaccinated calves did not lose any weight, which is an excellent indicator of the well-being of an animal and has a significant economic impact. Furthermore, the interval between the two vaccinations did not influence the magnitude of the immune responses or degree of clinical protection, and a third immunization was not necessary or beneficial. Since electroporation may enhance not only the magnitude but also the duration of immunity after DNA immunization, the interval between vaccination and challenge was extended in a second trial, which showed that two doses of this E2 DNA vaccine again significantly reduced clinical disease against BVDV for several months. These results are promising and support this technology for use against infectious diseases in cattle and large species, including humans, in general.

  6. Early effects comparison of X-rays delivered at high-dose-rate pulses by a plasma focus device and at low dose rate on human tumour cells.

    PubMed

    Virelli, A; Zironi, I; Pasi, F; Ceccolini, E; Nano, R; Facoetti, A; Gavoçi, E; Fiore, M R; Rocchi, F; Mostacci, D; Cucchi, G; Castellani, G; Sumini, M; Orecchia, R

    2015-09-01

    A comparative study has been performed on the effects of high-dose-rate (DR) X-ray beams produced by a plasma focus device (PFMA-3), to exploit its potential medical applications (e.g. radiotherapy), and low-DR X-ray beams produced by a conventional source (XRT). Experiments have been performed at 0.5 and 2 Gy doses on a human glioblastoma cell line (T98G). Cell proliferation rate and potassium outward currents (IK) have been investigated by time lapse imaging and patch clamp recordings. The results showed that PFMA-3 irradiation has a greater capability to reduce the proliferation rate activity with respect to XRT, while it does not affect IK of T98G cells at any of the dose levels tested. XRT irradiation significantly reduces the mean IK amplitude of T98G cells only at 0.5 Gy. This work confirms that the DR, and therefore the source of radiation, is crucial for the planning and optimisation of radiotherapy applications. PMID:25883300

  7. Early effects comparison of X-rays delivered at high-dose-rate pulses by a plasma focus device and at low dose rate on human tumour cells.

    PubMed

    Virelli, A; Zironi, I; Pasi, F; Ceccolini, E; Nano, R; Facoetti, A; Gavoçi, E; Fiore, M R; Rocchi, F; Mostacci, D; Cucchi, G; Castellani, G; Sumini, M; Orecchia, R

    2015-09-01

    A comparative study has been performed on the effects of high-dose-rate (DR) X-ray beams produced by a plasma focus device (PFMA-3), to exploit its potential medical applications (e.g. radiotherapy), and low-DR X-ray beams produced by a conventional source (XRT). Experiments have been performed at 0.5 and 2 Gy doses on a human glioblastoma cell line (T98G). Cell proliferation rate and potassium outward currents (IK) have been investigated by time lapse imaging and patch clamp recordings. The results showed that PFMA-3 irradiation has a greater capability to reduce the proliferation rate activity with respect to XRT, while it does not affect IK of T98G cells at any of the dose levels tested. XRT irradiation significantly reduces the mean IK amplitude of T98G cells only at 0.5 Gy. This work confirms that the DR, and therefore the source of radiation, is crucial for the planning and optimisation of radiotherapy applications.

  8. Estimation of absorbed dose to the kidneys in patients after treatment with 177Lu-octreotate: comparison between methods based on planar scintigraphy

    PubMed Central

    2012-01-01

    Background Lu-[DOTA0, Tyr3]-octreotate (177Lu-octreotate) is used to treat neuroendocrine tumors with high somatostatin-receptor expression. 177Lu-octreotate is mainly excreted via the kidneys, but to some extent, accumulates in the kidney cortex due to, e.g., tubular reabsorption. Renal toxicity is one of the main limiting factors in 177Lu-octreotate treatment. Further knowledge of the biodistribution and dosimetry of 177Lu-octreotate in individual patients is needed. The aim of this study was to estimate the absorbed dose to the kidneys and compare the results obtained with planar imaging and different dosimetric methods: (1) conjugate-view (CV) method using patient-specific kidney sizes, (2) PA method, based on posterior images only, (3) CV method with reduced number of time points (CVreduced data), and (4) CV method using standard kidney sizes (CVstandard size). Methods Totally, 33 patients each received 3.4 to 8.2 GBq of 177Lu-octreotate up to five times, with infusion of lysine and arginine to block the renal uptake. Whole-body planar gamma camera images were acquired on days 0, 1, 2, and 7. The 177Lu concentration in the kidneys was determined by the CV method, and the absorbed dose was estimated with patient-specific organ sizes. Comparison to the CV method was made using posterior images only, together with the influence of the number of time points and with standard organ sizes. Results Large interindividual variations were found in the time-activity curve pattern and in the absorbed dose to the kidneys using the CV method: 0.33 to 2.4 Gy/GBq (mean =  0.80 Gy/GBq, SD = 0.30). In the individual patient, the mean deviation of all subsequent kidney doses compared to that of the first administration was 1% (SD = 19%) and 5% (SD = 23%) for the right and left kidneys, respectively. Excluding data for day 7 resulted in large variations in the absorbed dose. Conclusion Large interindividual variations in kidney dose were found, demonstrating the

  9. Using LiF:Mg,Cu,P TLDs to estimate the absorbed dose to water in liquid water around an {sup 192}Ir brachytherapy source

    SciTech Connect

    Lucas, P. Avilés Aubineau-Lanièce, I.; Lourenço, V.; Vermesse, D.; Cutarella, D.

    2014-01-15

    Purpose: The absorbed dose to water is the fundamental reference quantity for brachytherapy treatment planning systems and thermoluminescence dosimeters (TLDs) have been recognized as the most validated detectors for measurement of such a dosimetric descriptor. The detector response in a wide energy spectrum as that of an{sup 192}Ir brachytherapy source as well as the specific measurement medium which surrounds the TLD need to be accounted for when estimating the absorbed dose. This paper develops a methodology based on highly sensitive LiF:Mg,Cu,P TLDs to directly estimate the absorbed dose to water in liquid water around a high dose rate {sup 192}Ir brachytherapy source. Methods: Different experimental designs in liquid water and air were constructed to study the response of LiF:Mg,Cu,P TLDs when irradiated in several standard photon beams of the LNE-LNHB (French national metrology laboratory for ionizing radiation). Measurement strategies and Monte Carlo techniques were developed to calibrate the LiF:Mg,Cu,P detectors in the energy interval characteristic of that found when TLDs are immersed in water around an{sup 192}Ir source. Finally, an experimental system was designed to irradiate TLDs at different angles between 1 and 11 cm away from an {sup 192}Ir source in liquid water. Monte Carlo simulations were performed to correct measured results to provide estimates of the absorbed dose to water in water around the {sup 192}Ir source. Results: The dose response dependence of LiF:Mg,Cu,P TLDs with the linear energy transfer of secondary electrons followed the same variations as those of published results. The calibration strategy which used TLDs in air exposed to a standard N-250 ISO x-ray beam and TLDs in water irradiated with a standard{sup 137}Cs beam provided an estimated mean uncertainty of 2.8% (k = 1) in the TLD calibration coefficient for irradiations by the {sup 192}Ir source in water. The 3D TLD measurements performed in liquid water were obtained with a

  10. Neutron relative biological effectiveness for solid cancer incidence in the Japanese A-bomb survivors: an analysis considering the degree of independent effects from γ-ray and neutron absorbed doses with hierarchical partitioning.

    PubMed

    Walsh, Linda

    2013-03-01

    It has generally been assumed that the neutron and γ-ray absorbed doses in the data from the life span study (LSS) of the Japanese A-bomb survivors are too highly correlated for an independent separation of the all solid cancer risks due to neutrons and due to γ-rays. However, with the release of the most recent data for all solid cancer incidence and the increased statistical power over previous datasets, it is instructive to consider alternatives to the usual approaches. Simple excess relative risk (ERR) models for radiation-induced solid cancer incidence fitted to the LSS epidemiological data have been applied with neutron and γ-ray absorbed doses as separate explanatory covariables. A simple evaluation of the degree of independent effects from γ-ray and neutron absorbed doses on the all solid cancer risk with the hierarchical partitioning (HP) technique is presented here. The degree of multi-collinearity between the γ-ray and neutron absorbed doses has also been considered. The results show that, whereas the partial correlation between the neutron and γ-ray colon absorbed doses may be considered to be high at 0.74, this value is just below the level beyond which remedial action, such as adding the doses together, is usually recommended. The resulting variance inflation factor is 2.2. Applying HP indicates that just under half of the drop in deviance resulting from adding the γ-ray and neutron absorbed doses to the baseline risk model comes from the joint effects of the neutrons and γ-rays-leaving a substantial proportion of this deviance drop accounted for by individual effects of the neutrons and γ-rays. The average ERR/Gy γ-ray absorbed dose and the ERR/Gy neutron absorbed dose that have been obtained here directly for the first time, agree well with previous indirect estimates. The average relative biological effectiveness (RBE) of neutrons relative to γ-rays, calculated directly from fit parameters to the all solid cancer ERR model with both

  11. High-Dose-Rate Brachytherapy as Monotherapy Delivered in Two Fractions Within One Day for Favorable/Intermediate-Risk Prostate Cancer: Preliminary Toxicity Data

    SciTech Connect

    Ghilezan, Michel; Martinez, Alvaro; Gustason, Gary; Krauss, Daniel; Antonucci, J. Vito; Chen, Peter; Fontanesi, James; Wallace, Michelle; Ye Hong; Casey, Alyse; Sebastian, Evelyn; Kim, Leonard; Limbacher, Amy

    2012-07-01

    Purpose: To report the toxicity profile of high-dose-rate (HDR)-brachytherapy (BT) as monotherapy in a Human Investigation Committee-approved study consisting of a single implant and two fractions (12 Gy Multiplication-Sign 2) for a total dose of 24 Gy, delivered within 1 day. The dose was subsequently increased to 27 Gy (13.5 Gy Multiplication-Sign 2) delivered in 1 day. We report the acute and early chronic genitourinary and gastrointestinal toxicity. Methods and Materials: A total of 173 patients were treated between December 2005 and July 2010. However, only the first 100 were part of the IRB-approved study and out of these, only 94 had a minimal follow-up of 6 months, representing the study population for this preliminary report. All patients had clinical Stage T2b or less (American Joint Committee on Cancer, 5th edition), Gleason score 6-7 (3+4), and prostate-specific antigen level of {<=}12 ng/mL. Ultrasound-guided HDR-BT with real-time dosimetry was used. The prescription dose was 24 Gy for the first 50 patients and 27 Gy thereafter. The dosimetric goals and constraints were the same for the two dose groups. Toxicity was scored using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 3. The highest toxicity scores encountered at any point during follow-up are reported. Results: The median follow-up was 17 months (range, 6-40.5). Most patients had Grade 0-1 acute toxicity. The Grade 2 acute genitourinary toxicity was mainly frequency/urgency (13%), dysuria (5%), hematuria, and dribbling/hesitancy (2%). None of the patients required a Foley catheter at any time; however, 8% of the patients experienced transient Grade 1 diarrhea. No other acute gastrointestinal toxicities were found. The most common chronic toxicity was Grade 2 urinary frequency/urgency in 16% of patients followed by dysuria in 4% of patients; 2 patients had Grade 2 rectal bleeding and 1 had Grade 4, requiring laser treatment. Conclusions: Favorable

  12. SU-F-18C-08: A Validation Study of a Commercially Available Software Package's Absorbed Dose Estimates in a Physical Phantom

    SciTech Connect

    Supanich, M; Siegelman, J

    2014-06-15

    Purpose: This study assesses the accuracy of the absorbed dose estimates from CT scans generated by Monte Carlo (MC) simulation using a commercially available radiation dose monitoring software program. Methods: Axial CT studies of an anthropomorphic abdomen phantom with dose bores at a central location and 4 peripheral locations were conducted using a fixed tube current at 120 kV. A 100 mm ion chamber and a 0.6 cc ion chamber calibrated at diagnostic energy levels were used to measure dose in the phantom at each of the 5 dose bore locations. Simulations using the software program's Monte Carlo engine were run using a mathematical model of the anthropomorphic phantom to determine conversion coefficients between the CTDIvol used for the study and the dose at the location of the dose bores. Simulations were conducted using both the software's generic CT beam model and a refined model generated using HVL and bow tie filter profile measurements made on the scanner used for the study. Results: Monte Carlo simulations completed using the generalized beam model differed from the measured conversion factors by an absolute value average of 13.0% and 13.8% for the 100 mm and 0.6 cc ion chamber studies, respectively. The MC simulations using the scanner specific beam model generated conversion coefficients that differed from the CTDIvol to measured dose conversion coefficients by an absolute value average of 7.3% and 7.8% for the 100 mm and 0.6 cc ion chamber cases, respectively. Conclusion: A scanner specific beam model used in MC simulations generates more accurate dose conversion coefficients in an anthropomorphic phantom than those generated with a generalized beam model. Agreement between measured conversion coefficients and simulated values were less than 20% for all positions using the universal beam model.

  13. Dynamic evaluation of absorbed dose to the bladder wall with a balloon-bladder phantom during a study using [(18)F]fluorodeoxyglucose positron emission imaging.

    PubMed

    Wu, T H; Liu, R S; Dong, S L; Chung, Y W; Chou, K L; Lee, J S

    2002-08-01

    An accurate evaluation of the absorbed dose to the bladder wall from 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG) is clinically important because the bladder is considered as a critical organ in most positron emission tomography (PET) studies that cumulate about 20% of the total activity injection during image procedures. In the MIRD calculation, no allowance is made for the inclusion of all the dynamic parameters that affect the actual dose to the bladder wall to be taken in the dose assessment. The goal of the study is to propose a dose evaluation model by using a dynamic bladder phantom and time-activity curves from the bladder PET imaging. The proposed model takes all dynamic parameters into account and provides a much more accurate dose estimation to the bladder. In this study, the lowest dose to the bladder wall was obtained at the conditions of having a larger initial volume for the bladder contents and a higher production rate for urine. It is then advised patients to drink a bulk amount of water before the FDG injection or after urine voiding to facilitate urine production and to enlarge the bladder surface area, which are the most crucial steps in reducing the dose to the bladder wall. In our study, the voiding schedule in dose calculation plays certain roles although it is much more critical in the conventional MIRD calculation. The model estimated that the lowest dose to the bladder would occur at an initial void about 40 min after the FDG injection and the urine voiding was as complete as possible. PMID:12124480

  14. Treatment of small-cell lung cancer xenografts with iodine-313-anti-neural cell adhesion molecule monoclonal antibody and evaluation of absorbed dose in tissue

    SciTech Connect

    Hosono, Makoto; Endo, Keigo; Hosono, Masako N.

    1994-02-01

    Human small-cell lung cancer (SCLC) is considered a feasible target for immunotherapy using a radiolabeled monoclonal antibody (Mab). A murine Mab, NE150 (IgG1), reacts with the neural cell adhesion molecule, which is identical to cluster 1 antigen of SCLC. To estimate their therapeutic effects, NE150 and an isotype-matched control Mab were labeled with {sup 131}I and administered intravenously as a single dose into athymic mice inoculated with a NCI-H69 SCLC xenograft. The absorbed dose in organs was also examined based upon a long-term biodistribution study of {sup 131}I-NE150. Tumors initial volume 563.4 {plus_minus} 223.5 mm{sup 3} treated with 11.1 MBq (300 {mu}Ci) of {sup 131}I-NE150 diminished and became invisible at days 30-33, demonstrating a 60-day mean growth delay to reach a tripled initial volume compared with sham-treated tumors. Cumulative absorbed doses were estimated to be 2310, 410, 500, 330, and 790 cGy for the tumor, liver, kidney, spleen and lung, respectively. Iodine-131-NE150 had potent therapeutic effects against SCLC transplants in athymic mice, however, careful assessment of the side effects, improvement of radioiodination and chimerization of the Mab might be necessary to achieve efficient targeting in clinical therapeutic applications. 25 refs., 2 figs., 3 tabs.

  15. Monte Carlo evaluations of the absorbed dose and quality dependence of Al{sub 2}O{sub 3} in radiotherapy photon beams

    SciTech Connect

    Chen Shaowen; Wang Xuetao; Chen Lixin; Tang Qiang; Liu Xiaowei

    2009-10-15

    Purpose: The purpose of this work was to evaluate the absorbed dose to Al{sub 2}O{sub 3} dosimeter at various depths of water phantom in radiotherapy photon beams by Monte Carlo simulation and evaluate the beam quality dependence. Methods: The simulations were done using EGSnrc. The cylindrical Al{sub 2}O{sub 3} dosimeter ({Phi}4 mmx1 mm) was placed at the central axis of the water phantom ({Phi}16 cmx16 cm) at depths between 0.5 and 8 cm. The incident beams included monoenergetic photon beams ranging from 1 to 18 MeV, {sup 60}Co {gamma} beams, Varian 6 MV beams using phase space files based on a full simulation of the linac, and Varian beams between 4 and 24 MV using Mohan's spectra. The absorbed dose to the dosimeter and the water at the corresponding position in the absence of the dosimeter, as well as absorbed dose ratio factor f{sub md}, was calculated. Results: The results show that f{sub md} depends obviously on the photon energy at the shallow depths. However, as the depth increases, the change in f{sub md} becomes small, beyond the buildup region, the maximum discrepancy of f{sub md} to the average value is not more than 1%. Conclusions: These simulation results confirm the use of Al{sub 2}O{sub 3} dosimeter in radiotherapy photon beams and clearly indicate that more attention should be paid when using such a dosimeter in the buildup region of high-energy radiotherapy photon beams.

  16. Role of shielding in modulating the effects of solar particle events: Monte Carlo calculation of absorbed dose and DNA complex lesions in different organs

    NASA Technical Reports Server (NTRS)

    Ballarini, F.; Biaggi, M.; De Biaggi, L.; Ferrari, A.; Ottolenghi, A.; Panzarasa, A.; Paretzke, H. G.; Pelliccioni, M.; Sala, P.; Scannicchio, D.; Zankl, M.; Townsend, L. W. (Principal Investigator)

    2004-01-01

    Distributions of absorbed dose and DNA clustered damage yields in various organs and tissues following the October 1989 solar particle event (SPE) were calculated by coupling the FLUKA Monte Carlo transport code with two anthropomorphic phantoms (a mathematical model and a voxel model), with the main aim of quantifying the role of the shielding features in modulating organ doses. The phantoms, which were assumed to be in deep space, were inserted into a shielding box of variable thickness and material and were irradiated with the proton spectra of the October 1989 event. Average numbers of DNA lesions per cell in different organs were calculated by adopting a technique already tested in previous works, consisting of integrating into "condensed-history" Monte Carlo transport codes--such as FLUKA--yields of radiobiological damage, either calculated with "event-by-event" track structure simulations, or taken from experimental works available in the literature. More specifically, the yields of "Complex Lesions" (or "CL", defined and calculated as a clustered DNA damage in a previous work) per unit dose and DNA mass (CL Gy-1 Da-1) due to the various beam components, including those derived from nuclear interactions with the shielding and the human body, were integrated in FLUKA. This provided spatial distributions of CL/cell yields in different organs, as well as distributions of absorbed doses. The contributions of primary protons and secondary hadrons were calculated separately, and the simulations were repeated for values of Al shielding thickness ranging between 1 and 20 g/cm2. Slight differences were found between the two phantom types. Skin and eye lenses were found to receive larger doses with respect to internal organs; however, shielding was more effective for skin and lenses. Secondary particles arising from nuclear interactions were found to have a minor role, although their relative contribution was found to be larger for the Complex Lesions than for the

  17. Production and in vivo imaging of (203)Pb as a surrogate isotope for in vivo (212)Pb internal absorbed dose studies.

    PubMed

    Máthé, Domokos; Szigeti, Krisztián; Hegedűs, Nikolett; Horváth, Ildikó; Veres, Dániel S; Kovács, Béla; Szűcs, Zoltán

    2016-08-01

    (212)Pb is a clinically relevant therapeutic alpha emitter isotope. A surrogate, (203)Pb, if prepared with sufficiently high specific activity could be used to estimate (212)Pb in vivo absorbed doses. An improved production procedure of (203)Pb with a simple, new separation method and high specific radioactivity for imaging is reported. We determined the in-vivo biodistribution of (203)Pb in mice by SPECT/CT. This highlights application possibilities of (203)Pb for further in vivo and clinical uses (radiolabeled (212)Pb-peptide co-injection, dosimetry calculation).

  18. SU-F-19A-02: Comparison of Absorbed Dose to Water Standards for HDR Ir-192 Brachytherapy Between the LCR, Brazil and NRC, Canada

    SciTech Connect

    Salata, C; David, M; Almeida, C de; El Gamal, I; Cojocaru, C; Mainegra-Hing, E; McEwen, M

    2014-06-15

    Purpose: To compare absorbed dose to water standards for HDR brachytherapy dosimetry developed by the Radiological Science Laboratory of Rio de Janeiro State University (LCR) and the National Research Council, Canada (NRC). Methods: The two institutions have separately developed absorbed dose standards based on the Fricke dosimetry system. There are important differences between the two standards, including: preparation and read-out of the Fricke solution, irradiation geometry of the Fricke holder in relation to the Ir-192 source, and determination of the G-value to be used at Ir-192 energies. All measurements for both standards were made directly at the NRC laboratory (i.e., no transfer instrument was used) using a single Ir-192 source (microSelectron v2). In addition, the NRC group has established a self-consistent method to determine the G-value for Ir-192, based on an interpolation between G-values obtained at Co-60 and 250kVp X-rays, and this measurement was repeated using the LCR Fricke solution to investigate possible systematic uncertainties. Results: G-values for Co-60 and 250 kVp x-rays, obtained using the LCR Fricke system, agreed with the NRC values within 0.5 % and 1 % respectively, indicating that the general assumption of universal G-values is appropriate in this case. The standard uncertainty in the determination of G for Ir-192 is estimated to be 0.6 %. For the comparison of absorbed dose measurements at the reference point for Ir-192 (1 cm depth in water, perpendicular to the seed long-axis), the ratio Dw(NRC)/Dw(LCR) was found to be 1.011 with a combined standard uncertainty of 1.7 %, k=1. Conclusion: The agreement in the absorbed dose to water values for the LCR and NRC systems is very encouraging. Combined with the lower uncertainty in this approach compared to the present air-kerma approach, these results reaffirm the use of Fricke solution as a potential primary standard for HDR Ir-192 brachytherapy.

  19. Role of cardiac ultrafast cameras with CZT solid-state detectors and software developments on radiation absorbed dose reduction to the patients.

    PubMed

    Gunalp, Bengul

    2015-07-01

    Myocardial perfusion imaging (MPI) is one the most contributing nuclear medicine technique to the annual population dose. The purpose of this study is to compare radiation-absorbed doses to the patients examined by conventional cardiac SPECT (CSPECT) camera and ultrafast cardiac (UFC) camera with cadmium-zinc-telluride (CZT) solid-state detectors. Total injected activity was reduced by 50 % when both stress and rest images were acquired and by 75 % when only stress images were taken with UFC camera. As a result of this, the mean total effective dose was found significantly lower with UFC camera (2.2 ± 1.2 mSv) than CSPECT (7.7 ± 3.8 mSv) (p < 0.001). Further dose reduction was obtained by reducing equivocal test results and unnecessary additional examinations with UFC camera. Using UFC camera, MPI can be conveniently used for the detection of coronary artery disease (CAD) much less increasing annual population radiation dose as it had been before. PMID:25848109

  20. 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...

  1. Efficacy and Immunogenicity of Single-Dose AdVAV Intranasal Anthrax Vaccine Compared to Anthrax Vaccine Absorbed in an Aerosolized Spore Rabbit Challenge Model

    PubMed Central

    Krishnan, Vyjayanthi; Andersen, Bo H.; Shoemaker, Christine; Sivko, Gloria S.; Tordoff, Kevin P.; Stark, Gregory V.; Zhang, Jianfeng; Feng, Tsungwei; Duchars, Matthew

    2015-01-01

    AdVAV is a replication-deficient adenovirus type 5-vectored vaccine expressing the 83-kDa protective antigen (PA83) from Bacillus anthracis that is being developed for the prevention of disease caused by inhalation of aerosolized B. anthracis spores. A noninferiority study comparing the efficacy of AdVAV to the currently licensed Anthrax Vaccine Absorbed (AVA; BioThrax) was performed in New Zealand White rabbits using postchallenge survival as the study endpoint (20% noninferiority margin for survival). Three groups of 32 rabbits were vaccinated with a single intranasal dose of AdVAV (7.5 × 107, 1.5 × 109, or 3.5 × 1010 viral particles). Three additional groups of 32 animals received two doses of either intranasal AdVAV (3.5 × 1010 viral particles) or intramuscular AVA (diluted 1:16 or 1:64) 28 days apart. The placebo group of 16 rabbits received a single intranasal dose of AdVAV formulation buffer. All animals were challenged via the inhalation route with a targeted dose of 200 times the 50% lethal dose (LD50) of aerosolized B. anthracis Ames spores 70 days after the initial vaccination and were followed for 3 weeks. PA83 immunogenicity was evaluated by validated toxin neutralizing antibody and serum anti-PA83 IgG enzyme-linked immunosorbent assays (ELISAs). All animals in the placebo cohort died from the challenge. Three of the four AdVAV dose cohorts tested, including two single-dose cohorts, achieved statistical noninferiority relative to the AVA comparator group, with survival rates between 97% and 100%. Vaccination with AdVAV also produced antibody titers with earlier onset and greater persistence than vaccination with AVA. PMID:25673303

  2. Efficacy and immunogenicity of single-dose AdVAV intranasal anthrax vaccine compared to anthrax vaccine absorbed in an aerosolized spore rabbit challenge model.

    PubMed

    Krishnan, Vyjayanthi; Andersen, Bo H; Shoemaker, Christine; Sivko, Gloria S; Tordoff, Kevin P; Stark, Gregory V; Zhang, Jianfeng; Feng, Tsungwei; Duchars, Matthew; Roberts, M Scot

    2015-04-01

    AdVAV is a replication-deficient adenovirus type 5-vectored vaccine expressing the 83-kDa protective antigen (PA83) from Bacillus anthracis that is being developed for the prevention of disease caused by inhalation of aerosolized B. anthracis spores. A noninferiority study comparing the efficacy of AdVAV to the currently licensed Anthrax Vaccine Absorbed (AVA; BioThrax) was performed in New Zealand White rabbits using postchallenge survival as the study endpoint (20% noninferiority margin for survival). Three groups of 32 rabbits were vaccinated with a single intranasal dose of AdVAV (7.5 × 10(7), 1.5 × 10(9), or 3.5 × 10(10) viral particles). Three additional groups of 32 animals received two doses of either intranasal AdVAV (3.5 × 10(10) viral particles) or intramuscular AVA (diluted 1:16 or 1:64) 28 days apart. The placebo group of 16 rabbits received a single intranasal dose of AdVAV formulation buffer. All animals were challenged via the inhalation route with a targeted dose of 200 times the 50% lethal dose (LD50) of aerosolized B. anthracis Ames spores 70 days after the initial vaccination and were followed for 3 weeks. PA83 immunogenicity was evaluated by validated toxin neutralizing antibody and serum anti-PA83 IgG enzyme-linked immunosorbent assays (ELISAs). All animals in the placebo cohort died from the challenge. Three of the four AdVAV dose cohorts tested, including two single-dose cohorts, achieved statistical noninferiority relative to the AVA comparator group, with survival rates between 97% and 100%. Vaccination with AdVAV also produced antibody titers with earlier onset and greater persistence than vaccination with AVA.

  3. A two one-sided parametric tolerance interval test for control of delivered dose uniformity. Part 1--characterization of FDA proposed test.

    PubMed

    Novick, Steven; Christopher, David; Dey, Monisha; Lyapustina, Svetlana; Golden, Michael; Leiner, Stefan; Wyka, Bruce; Delzeit, Hans-Joachim; Novak, Chris; Larner, Gregory

    2009-01-01

    The FDA proposed a parametric tolerance interval (PTI) test at the October 2005 Advisory Committee meeting as a replacement of the attribute (counting) test for delivered dose uniformity (DDU), published in the 1998 draft guidance for metered dose inhalers (MDIs) and dry powder inhalers (DPIs) and the 2002 final guidance for inhalation sprays and intranasal products. This article (first in a series of three) focuses on the test named by the FDA "87.5% coverage." Unlike a typical two-sided PTI test, which controls the proportion of the DDU distribution within a target interval (coverage), this test is comprised of two one-sided tests (TOST) designed to control the maximum amount of DDU values in either tail of the distribution above and below the target interval. Through simulations, this article characterizes the properties and performance of the proposed PTI-TOST under different scenarios. The results show that coverages of 99% or greater are needed for a batch to have acceptance probability 98% or greater with the test named by the FDA "87.5% coverage" (95% confidence level), while batches with 87.5% coverage have less than 1% probability of being accepted. The results also illustrate that with this PTI-TOST, the coverage requirement for a given acceptance probability increases as the batch mean deviates from target. The accompanying articles study the effects of changing test parameters and the test robustness to deviations from normality.

  4. A two one-sided parametric tolerance interval test for control of delivered dose uniformity--part 3--investigation of robustness to deviations from normality.

    PubMed

    Novick, Steven; Christopher, David; Dey, Monisha; Lyapustina, Svetlana; Golden, Michael; Leiner, Stefan; Wyka, Bruce; Delzeit, Hans-Joachim; Novak, Chris; Larner, Gregory

    2009-01-01

    The robustness of the parametric tolerance interval test, which was proposed by the Food and Drug Administration for control of delivered dose uniformity in orally inhaled and nasal drug products, is investigated in this article using different scenarios for deviations from a univariate normal distribution. The studied scenarios span a wide range of conditions, the purpose of which is to provide an understanding of how the test performs depending on the nature and degree of the deviation from normality. Operating characteristic curves were generated to compare the performance of the test for different types of distributions (normal and non-normal) having the same proportion of doses in the tails (on one or both sides) outside the target interval. The results show that, in most cases, non-normality does not increase the probability of accepting a batch of unacceptable quality (i.e., the test is robust) except in extreme situations, which do not necessarily represent commercially viable products. The results also demonstrate that, in the case of bimodal distributions where the life-stage means differ from each other by up to 24% label claim, the test's criterion on life-stage means does not affect pass rates because the tolerance interval portion of the test reacts to shifting means as well.

  5. Calculation of the absorbed dose for the overexposed patients at the JCO criticality accident in Tokai-mura.

    PubMed

    Ishigure, N; Endo, A; Yamaguchi, Y; Kawachi, K

    2001-09-01

    The doses for the overexposed patients were estimated by the measurement result of specific activity of 24Na in blood. The present method is almost based on documents of the International Atomic Energy Agency (IAEA) and the Oak Ridge National Laboratory. The neutron energy spectrum obtained using the ANISN code (Multigroup One-Dimensional Discrete Ordinates Transport Code System with Anisotropic Scattering) was assumed. The values in ICRP Publication 74 were applied for the doses in each organ per unit neutron fluence. Gamma-ray dose was indirectly estimated based on (a) the result of environmental monitoring around the accident site and (b) a graph in IAEA manual, which gives the kerma ratio of neutrons and gamma-rays as a function of the critical volume or the atomic ratio of hydrogen to 235U. The estimated neutron doses were 5.4 Gy for patient A. 2.9 Gy for patient B and 0.81 Gy for patient C. The estimated gamma-ray doses were 8.5 or 13 Gy for patient A, 4.5 or 6.9 Gy for patient B, and 1.3 or 2.0 Gy for patient C. PMID:11791747

  6. Structural changes caused by radiation-induced reduction and radiolysis: the effect of X-ray absorbed dose in a fungal multicopper oxidase

    PubMed Central

    De la Mora, Eugenio; Lovett, Janet E.; Blanford, Christopher F.; Garman, Elspeth F.; Valderrama, Brenda; Rudino-Pinera, Enrique

    2012-01-01

    X-ray radiation induces two main effects at metal centres contained in protein crystals: radiation-induced reduction and radiolysis and a resulting decrease in metal occupancy. In blue multicopper oxidases (BMCOs), the geometry of the active centres and the metal-to-ligand distances change depending on the oxidation states of the Cu atoms, suggesting that these alterations are catalytically relevant to the binding, activation and reduction of O2. In this work, the X-ray-determined three-dimensional structure of laccase from the basidiomycete Coriolopsis gallica (Cg L), a high catalytic potential BMCO, is described. By combining spectroscopic techniques (UV–Vis, EPR and XAS) and X-ray crystallography, structural changes at and around the active copper centres were related to pH and absorbed X-­ray dose (energy deposited per unit mass). Depletion of two of the four active Cu atoms as well as low occupancies of the remaining Cu atoms, together with different conformations of the metal centres, were observed at both acidic pH and high absorbed dose, correlating with more reduced states of the active coppers. These observations provide additional evidence to support the role of flexibility of copper sites during O2 reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account. PMID:22525754

  7. Comparison of the calculated absorbed dose using the Cadplan™ treatment planning software and Tld-100 measurements in an Alderson-Rando phantom for a bronchogenic treatment

    SciTech Connect

    Gutiérrez Castillo, J. G.; Álvarez Romero, J. T. E-mail: fisarmandotorres@gmail.com Calderón, A. Torres E-mail: fisarmandotorres@gmail.com M, V. Tovar E-mail: fisarmandotorres@gmail.com

    2014-11-07

    To verify the accuracy of the absorbed doses D calculated by a TPS Cadplan for a bronchogenic treatment (in an Alderson-Rando phantom) are chosen ten points with the following D's and localizations. Point 1, posterior position on the left edge with 136.4 Gy. Points: 2, 3 and 4 in the left lung with 104.9, 104.3 and 105.8 Gy, respectively; points 5 and 6 at the mediastinum with 192.4 and 173.5 Gy; points 7, 8 and 9 in the right lung with 105.8, 104.2 and 104.7 Gy, and 10 at posterior position on right edge with 143.7 Gy. IAEA type capsules with TLD 100 powder are placed, planned and irradiated. The evaluation of the absorbed dose is carried out a curve of calibration for the LiF response (nC) {sup vs} {sup DW}, to several cavity theories. The traceability for the DW is obtained with a secondary standard calibrated at the NRC (Canada). The dosimetric properties for the materials considered are determined from the Hounsfield numbers reported by the TPS. The stopping power ratios are calculated for nominal spectrum to 6 MV photons. The percent variations among the planned and determined D in all the cases they are < ± 3%.

  8. The effect of differences in data base on the determination of absorbed dose in high-energy photon beams using the American Association of Physicists in Medicine protocol.

    PubMed

    Mijnheer, B J; Chin, L M

    1989-01-01

    Exposure rates were adjusted at the National Institute of Standards and Technology (NIST) on January 1, 1986 to take into account more recent values for some physical parameters, mainly in electron stopping power ratios. Exposure calibration factors for 60Co gamma rays Nx will therefore be lowered by 1.1%. Consequently, absorbed dose determinations in high-energy photon beams will be reduced by the same amount if the values for these physical parameters remain unchanged in the American Association of Physicists in Medicine (AAPM) protocol. If the same data base as used at NIST is applied in the AAPM protocol, then Ngas/Nx values, water-air stopping power ratios, and Pwall values will be different. The overall change in absorbed dose determinations using a consistent set of data will be a reduction of 0.8% for 60Co gamma rays and 1.5% for a 20-MV x-ray beam compared to the values before January 1, 1986. Since the net effect is small when different sets of data are applied, the new NIST exposure calibration factors may be used in combination with the AAPM protocol without significant error.

  9. Key comparison BIPM.RI(I)-K4 of the absorbed dose to water standards of the PTB, Germany and the BIPM in 60Co gamma radiation

    NASA Astrophysics Data System (ADS)

    Kessler, C.; Burns, D. T.; Kapsch, R.-P.; Krauss, A.

    2016-01-01

    An indirect comparison has been made of the standards for absorbed dose to water in 60Co radiation of the Physikalisch-Technische Bundesanstalt, (PTB), Germany and of the Bureau International des Poids et Mesures (BIPM). The measurements at the BIPM were carried out in October 2015. The comparison result, based on the calibration coefficients for two transfer standards and evaluated as a ratio of the PTB and the BIPM standards for absorbed dose to water, is 0.9977 with a combined standard uncertainty of 3.8 × 10-3. The results are analysed and presented in terms of degrees of equivalence for entry in the BIPM key comparison database. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  10. Comparison of the calculated absorbed dose using the Cadplan™ treatment planning software and Tld-100 measurements in an Alderson-Rando phantom for a bronchogenic treatment

    NASA Astrophysics Data System (ADS)

    Gutiérrez Castillo, J. G.; Álvarez Romero, J. T.; Torres Calderón, A.; Tovar, M. V.

    2014-11-01

    To verify the accuracy of the absorbed doses D calculated by a TPS Cadplan for a bronchogenic treatment (in an Alderson-Rando phantom) are chosen ten points with the following D's and localizations. Point 1, posterior position on the left edge with 136.4 Gy. Points: 2, 3 and 4 in the left lung with 104.9, 104.3 and 105.8 Gy, respectively; points 5 and 6 at the mediastinum with 192.4 and 173.5 Gy; points 7, 8 and 9 in the right lung with 105.8, 104.2 and 104.7 Gy, and 10 at posterior position on right edge with 143.7 Gy. IAEA type capsules with TLD 100 powder are placed, planned and irradiated. The evaluation of the absorbed dose is carried out a curve of calibration for the LiF response (nC) vs DW, to several cavity theories. The traceability for the DW is obtained with a secondary standard calibrated at the NRC (Canada). The dosimetric properties for the materials considered are determined from the Hounsfield numbers reported by the TPS. The stopping power ratios are calculated for nominal spectrum to 6 MV photons. The percent variations among the planned and determined D in all the cases they are < ± 3%.

  11. An ICRP-based Chinese adult male voxel model and its absorbed dose for idealized photon exposures--the skeleton.

    PubMed

    Liu, Liye; Zeng, Zhi; Li, Junli; Zhang, Binquan; Qiu, Rui; Ma, Jizeng

    2009-11-01

    A site-specific skeleton voxel model for a Chinese adult male was constructed in this paper upon a previous Chinese individual voxel model. The whole skeleton was divided into 19 site-specific bones and bone groups; the mass of various skeleton tissues at each bone site, e.g. red bone marrow, was specified according to Asian reference data and the distribution data from ICRP Publication 70. The resultant voxel model (called CAM) has a resolution of 1.741 mm x 1.741 mm in plane, and the total bone mass is 8397.8 g which is almost equal to the Asian reference value. Dose coefficients for the red bone marrow and bone surface in CAM were calculated, and then compared with those from Rex, CMP and ICRP 74. It shows that the dose to RBM in Rex is generally 12% lower than that to CAM in low-energy range (30-150 keV) for AP, LAT, ROT and ISO geometries. It is also found that the RBM dose from mathematical models, i.e. CMP and ICRP 74, is underestimated by -30% in AP geometry and overestimated by 30% in PA geometry for low-energy photons. Meanwhile, the bone surface dose in the low-energy range is overestimated by 150% and 75% in CMP and ICRP 74, respectively, if compared with that from CAM. PMID:19841519

  12. An ICRP-based Chinese adult male voxel model and its absorbed dose for idealized photon exposures—the skeleton

    NASA Astrophysics Data System (ADS)

    Liu, Liye; Zeng, Zhi; Li, Junli; Zhang, Binquan; Qiu, Rui; Ma, Jizeng

    2009-11-01

    A site-specific skeleton voxel model for a Chinese adult male was constructed in this paper upon a previous Chinese individual voxel model. The whole skeleton was divided into 19 site-specific bones and bone groups; the mass of various skeleton tissues at each bone site, e.g. red bone marrow, was specified according to Asian reference data and the distribution data from ICRP Publication 70. The resultant voxel model (called CAM) has a resolution of 1.741 mm × 1.741 mm in plane, and the total bone mass is 8397.8 g which is almost equal to the Asian reference value. Dose coefficients for the red bone marrow and bone surface in CAM were calculated, and then compared with those from Rex, CMP and ICRP 74. It shows that the dose to RBM in Rex is generally 12% lower than that to CAM in low-energy range (30-150 keV) for AP, LAT, ROT and ISO geometries. It is also found that the RBM dose from mathematical models, i.e. CMP and ICRP 74, is underestimated by -30% in AP geometry and overestimated by 30% in PA geometry for low-energy photons. Meanwhile, the bone surface dose in the low-energy range is overestimated by 150% and 75% in CMP and ICRP 74, respectively, if compared with that from CAM.

  13. Experimental assessment of absorbed dose to mineralized bone tissue from internal emitters: An electron paramagnetic resonance study

    SciTech Connect

    Desrosiers, M.F.

    1994-12-31

    EPR resonances attributable to radiation-induced centers in hydroxyapatite were not detectable in bone samples supplied by the USTUR. These centers are the basis for imaging and dose assessment. Presumable, the short range of the alpha particles emitted precluded the formation of appreciable amounts of hydroxyapatite centers. However, one bone sample did offer a suggestion of hydroxyapatite centers and newly-developed methods to extract this information will be pursued.

  14. PHITS simulations of the Protective curtain experiment onboard the Service module of ISS: Comparison with absorbed doses measured with TLDs

    NASA Astrophysics Data System (ADS)

    Ploc, Ondřej; Sihver, Lembit; Kartashov, Dmitry; Shurshakov, Vyacheslav; Tolochek, Raisa

    2013-12-01

    "Protective curtain" was the physical experiment onboard the International Space Station (ISS) aimed on radiation measurement of the dose - reducing effect of the additional shielding made of hygienic water-soaked wipes and towels placed on the wall in the crew cabin of the Service module Zvezda. The measurements were performed with 12 detector packages composed of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs) placed at the Protective curtain, so that they created pairs of shielded and unshielded detectors.

  15. Assessing the safety of cosmetic chemicals: Consideration of a flux decision tree to predict dermally delivered systemic dose for comparison with oral TTC (Threshold of Toxicological Concern).

    PubMed

    Williams, Faith M; Rothe, Helga; Barrett, Gordon; Chiodini, Alessandro; Whyte, Jacqueline; Cronin, Mark T D; Monteiro-Riviere, Nancy A; Plautz, James; Roper, Clive; Westerhout, Joost; Yang, Chihae; Guy, Richard H

    2016-04-01

    Threshold of Toxicological Concern (TTC) aids assessment of human health risks from exposure to low levels of chemicals when toxicity data are limited. The objective here was to explore the potential refinement of exposure for applying the oral TTC to chemicals found in cosmetic products, for which there are limited dermal absorption data. A decision tree was constructed to estimate the dermally absorbed amount of chemical, based on typical skin exposure scenarios. Dermal absorption was calculated using an established predictive algorithm to derive the maximum skin flux adjusted to the actual 'dose' applied. The predicted systemic availability (assuming no local metabolism), can then be ranked against the oral TTC for the relevant structural class. The predictive approach has been evaluated by deriving the experimental/prediction ratio for systemic availability for 22 cosmetic chemical exposure scenarios. These emphasise that estimation of skin penetration may be challenging for penetration enhancing formulations, short application times with incomplete rinse-off, or significant metabolism. While there were a few exceptions, the experiment-to-prediction ratios mostly fell within a factor of 10 of the ideal value of 1. It can be concluded therefore, that the approach is fit-for-purpose when used as a screening and prioritisation tool.

  16. Extrapolation algorithm to Forecast the Dynamics of Accumulation of the Absorbed Dose at the International Space Station, according to the Radiation Monitoring System Data

    NASA Astrophysics Data System (ADS)

    Lishnevskii, Andrey

    The ISS service module is equipped with the radiation monitoring system (RMS) which provides data for the daily estimation of the radiation environment on board the station. The sensitive elements of the RMS are silicon semiconductor detectors and ionization chambers. The data obtained in quiet radiation environment allowed to determine the contribution to the absorbed radiation dose due to galactic cosmic rays and the Earth’s inner radiation belt. The corresponding analysis was conducted for the 2005-2011 period. As a result empirical relations were obtained allowing to calculate the dose for one crossing of the area of the South Atlantic Anomaly. The initial parameters for the calculation are longitude and altitude on which the ISS trajectory crosses this area. The obtained empirical relations allowed to develop a simple calculation algorithm for the short-term forecasting of the dynamics of accumulation of the radiation dose at the ISS which is based on the assumption that the current level of contribution to the daily dose of galactic cosmic rays and the structure of the Earth’s inner radiation belt at the station flight altitude remains unchanged within a few days. The results of the analysis of the ISS RMS data which was conducted using the developed calculation algorithm for the period from 2005 to 2011 (the period in which solar cycle 23 ended and solar cycle 24 began) showed the possibility to implement a short-term (1-2 days) forecast of the dynamics of accumulation of the dose on board the station with an acceptable error (of no more than 30 percent). Besides, the developed forecast algorithm for the growth phase of the 24th solar cycle (2011-2014) was verified. The algorithm developed for forecasting the radiation environment may be used to process and analyse the current RMS information when providing effective radiation safety for the ISS crew.

  17. A single dose of oral DNA immunization delivered by attenuated Salmonella typhimurium down-regulates transgene expression in HBsAg transgenic mice.

    PubMed

    Zheng, Bo Jian; Ng, Mun Hon; Chan, Kwok Wah; Tam, Sidney; Woo, Patrick C Y; Ng, Sze Park; Yuen, Kwok Yung

    2002-11-01

    The efficacy of immunization with Salmonella typhimurium aroA to deliver the plasmid pRc/CMV-HBsAg (i.e. an oral DNA vaccine) was compared with that of intramuscular immunization with the same plasmid DNA, and with recombinant HBsAg protein, in a HBsAg transgenic mouse model. A single dose of oral DNA vaccine evoked vigorous Th1 cell and CTL responses and production of IgG2 subclass of anti-HBs after 2 weeks, and this was accompanied by a transient hepatitic flare with elevated alanine aminotransferase in the first 3 weeks. Concomitantly, the level of HBsAg-mRNA in liver tissues decreased by more than fourfold and viral-antigen expression was curtailed markedly in hepatocytes compared with controls. Hepatitic flare subsided after 3 weeks, but suppression of the transgene expression was continued in the absence of overt liver pathology for the remaining duration of the experiment (i.e. 12 weeks), and possibly beyond. The other vaccines could also break immune tolerance, but this was achieved only after repeated booster doses of the respective vaccines, and they did not affect transgene expression, or induce hepatic flare. We previously showed in non-transgenic mice that immunization by the oral DNA vaccine is achieved by an active intestinal infection with a bacterial carrier that is an adept intracellular parasite, and the immune response to the vaccination is orchestrated by phagocytic APC. Our present findings further implicated that the combined effects of an innate and a specific immune response induced by oral DNA vaccination are crucial in down-regulating HBsAg-transgene expression in hepatocytes.

  18. Monte Carlo evaluation of the relationship between absorbed dose and contrast-to-noise ratio in coherent scatter breast CT

    NASA Astrophysics Data System (ADS)

    Ghammraoui, B.; Popescu, L. M.; Badal, A.

    2015-03-01

    The objective of this work was to evaluate the advantages and shortcomings associated with Coherent Scatter Computed Tomography (CSCT) systems for breast imaging and study possible alternative configurations. The relationship between dose in a breast phantom and a simple surrogate of image quality in pencil-beam and fan-beam CSCT geometries was evaluated via Monte Carlo simulation, and an improved pencil-beam setup was proposed for faster CSCT data acquisition. CSCT projection datasets of a simple breast phantom have been simulated using a new version of the MC-GPU code that includes an improved model of x-ray coherent scattering using experimentally measured molecular interference functions. The breast phantom was composed of an 8 cm diameter cylinder of 50/50 glandular/adipose material and nine rods with different diameters of cancerous, adipose and glandular tissues. The system performance has been assessed in terms of the contrast-to-noise ratio (CNR) in multiple regions of interest within the reconstructed images, for a range of exposure levels. The enhanced pencil-beam setup consisted of multiplexed pencil beams and specific post-processing of the projection data to calculate the scatter intensity coming from each beam separately. At reconstruction spatial resolution of 1×1×1 mm3 and from 1 to 10 mGy of received breast dose, fan-beam geometry showed higher statistical noise and lower CNR than pencil-beam geometry. Conventional CT acquisition had the highest CNR per dose. However, the CNR figure of merit did not combine yet all the information available at different scattering angles in the CSCT, which has potential for increased discrimination of materials with similar attenuation properties. Preliminary evaluation of the multiplexed pencil-beam geometry showed that the scattering profiles simulated with the new approach are similar to those of the single pencil-beam geometry. Conclusion: It has been shown that the GPU-accelerated MC-GPU code is a practical

  19. Monte Carlo estimation of radiation dose in organs of female and male adult phantoms due to FDG-F18 absorbed in the lungs

    NASA Astrophysics Data System (ADS)

    Belinato, Walmir; Santos, William S.; Silva, Rogério M. V.; Souza, Divanizia N.

    2014-03-01

    The determination of dose conversion factors (S values) for the radionuclide fluorodeoxyglucose (18F-FDG) absorbed in the lungs during a positron emission tomography (PET) procedure was calculated using the Monte Carlo method (MCNPX version 2.7.0). For the obtained dose conversion factors of interest, it was considered a uniform absorption of radiopharmaceutical by the lung of a healthy adult human. The spectrum of fluorine was introduced in the input data file for the simulation. The simulation took place in two adult phantoms of both sexes, based on polygon mesh surfaces called FASH and MASH with anatomy and posture according to ICRP 89. The S values for the 22 internal organs/tissues, chosen from ICRP No. 110, for the FASH and MASH phantoms were compared with the results obtained from a MIRD V phantoms called ADAM and EVA used by the Committee on Medical Internal Radiation Dose (MIRD). We observed variation of more than 100% in S values due to structural anatomical differences in the internal organs of the MASH and FASH phantoms compared to the mathematical phantom.

  20. Tumour dose estimation using automated TLD techniques.

    PubMed

    Ferguson, H M; Lambert, G D; Gustard, D; Harrison, R M

    1998-01-01

    Lithium fluoride (TLD-700) dosimeters were used to measure exit surface absorbed doses in external beam radiotherapy using an automated TLD reader. Delivered tumour absorbed doses were derived from these measurements for head and neck, pelvis and breast treatments. For the head and neck treatments (first fraction only), the mean percentage difference between prescribed and delivered tumour absorbed doses was -0.15 +/- 3.0% (+/- 1 SD), for the pelvic treatments -0.83 +/- 2.8% and for the breast treatments +0.26 +/- 2.9%. The spread of results is approximately +/- 3% (+/- 1 SD). This is comparable with the estimated uncertainty in a single TLD absorbed dose measurement in phantom (+/- 2%; +/- 1 SD). Thus, ICRU recommended tolerances for absorbed dose delivery of +/- 5% may not be unequivocally detectable using this method. An action level of +/- 10% is suggested, allowing investigation of possible gross errors in treatment delivery at an early stage, before the course of treatment has progressed to a point at which absorbed dose compensation is impossible.

  1. The expression revealing variation trend about radiation resistance of aromatic polymers serving in nuclear environment over absorbed dose

    NASA Astrophysics Data System (ADS)

    Lu, Shuangying; Hu, Huasi; Hu, Guang; Liu, Bin

    2015-03-01

    For polymeric materials applied in nuclear environment, the macroscopic properties usually remain unchanged after irradiation for several years or decades up to a threshold dose at which the deterioration of materials begins to take place. In this paper, the general radiation response of aromatic polymers is firstly reviewed and discussed. Then percolation theory is employed innovatively to elucidate the critical phenomenon over the service life for polymeric materials with high radiation resistance. For a better quantitative evaluation, a novel two-parameter radiation resistance model is proposed by the method of analogy between two nuclear-related phenomena. Six epoxy systems are employed from the published literatures to verify the novel model and the result shows that it is reliable and helpful in not only estimating the radiation damage over the service period but also multi-objective optimum design of polymeric materials.

  2. Structural changes caused by radiation-induced reduction and radiolysis: the effect of X-ray absorbed dose in a fungal multicopper oxidase

    SciTech Connect

    De la Mora, Eugenio; Lovett, Janet E.; Blanford, Christopher F.; Garman, Elspeth F.; Valderrama, Brenda; Rudino-Pinera, Enrique

    2012-05-01

    Radiation-induced reduction, radiolysis of copper sites and the effect of pH value together with the concomitant geometrical distortions of the active centres were analysed in several fungal (C. gallica) laccase structures collected at cryotemperature. This study emphasizes the importance of careful interpretation when the crystallographic structure of a metalloprotein is described. X-ray radiation induces two main effects at metal centres contained in protein crystals: radiation-induced reduction and radiolysis and a resulting decrease in metal occupancy. In blue multicopper oxidases (BMCOs), the geometry of the active centres and the metal-to-ligand distances change depending on the oxidation states of the Cu atoms, suggesting that these alterations are catalytically relevant to the binding, activation and reduction of O{sub 2}. In this work, the X-ray-determined three-dimensional structure of laccase from the basidiomycete Coriolopsis gallica (Cg L), a high catalytic potential BMCO, is described. By combining spectroscopic techniques (UV–Vis, EPR and XAS) and X-ray crystallography, structural changes at and around the active copper centres were related to pH and absorbed X-ray dose (energy deposited per unit mass). Depletion of two of the four active Cu atoms as well as low occupancies of the remaining Cu atoms, together with different conformations of the metal centres, were observed at both acidic pH and high absorbed dose, correlating with more reduced states of the active coppers. These observations provide additional evidence to support the role of flexibility of copper sites during O{sub 2} reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account.

  3. The biodistribution and dosimetry of {sup 117m}Sn DTPA with special emphasis on active marrow absorbed doses

    SciTech Connect

    Stubbs, J.; Atkins, H.

    1999-01-01

    {sup 117m}Sn(4+) DTPA is a new radiopharmaceutical for the palliation of pain associated with metastatic bone cancer. Recently, the Phase 2 clinical trials involving 47 patients were completed. These patients received administered activities in the range 6.7--10.6 MBq/kg of body mass. Frequent collections of urine were acquired over the first several hours postadministration and daily cumulative collections were obtained for the next 4--10 days. Anterior/posterior gamma camera images were obtained frequently over the initial 10 days. Radiation dose estimates were calculated for 8 of these patients. Each patient`s biodistribution data were mathematically simulated using a multicompartmental model. The model consisted of the following compartments: central, bone, kidney, other tissues, and cumulative urine. The measured cumulative urine data were used as references for the cumulative urine excretion compartment. The total-body compartment (sum of the bone surfaces, central, kidney, and other tissues compartments) was reference to all activity not excreted in the urine.

  4. EURAMET.RI(I)-S7 comparison of alanine dosimetry systems for absorbed dose to water measurements in gamma- and x-radiation at radiotherapy levels

    NASA Astrophysics Data System (ADS)

    Garcia, Tristan; Anton, Mathias; Sharpe, Peter

    2012-01-01

    The National Physical Laboratory (NPL), the Physikalisch-Technische Bundesanstalt (PTB) and the Laboratoire National Henri Becquerel (LNE-LNHB) are involved in the European project 'External Beam Cancer Therapy', a project of the European Metrology Research Programme. Within this project, the electron paramagnetic resonance (EPR)/alanine dosimetric method has been chosen for performing measurements in small fields such as those used in IMRT (intensity modulated radiation therapy). In this context, these three National Metrology Institutes (NMI) wished to compare the result of their alanine dosimetric systems (detector, modus operandi etc) at radiotherapy dose levels to check their consistency. This EURAMET.RI(I)-S7 comparison has been performed with the support of the Bureau International des Poids et Mesures (BIPM) which collected and distributed the results as a neutral organization, to ensure the comparison was 'blind'. Irradiations have been made under reference conditions by each laboratory in a 60Co beam and in an accelerator beam (10 MV or 12 MV) in a water phantom of 30 cm × 30 cm × 30 cm in a square field of 10 cm × 10 cm at the reference depth. Irradiations have been performed at known values of absorbed dose to water (Dw) within 10% of nominal doses of 5 Gy and 10 Gy, i.e. between 4.5 Gy and 5.5 Gy and between 9 Gy and 11 Gy, respectively. Each participant read out their dosimeters and assessed the doses using their own protocol (calibration curve, positioning device etc) as this comparison aims at comparing the complete dosimetric process. The results demonstrate the effectiveness of the EPR/alanine dosimetry systems operated by National Metrology Institutes as a method of assuring therapy level doses with the accuracy required. The maximum deviation in the ratio of measured to applied dose is less than 1%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key

  5. Fluence-to-Absorbed Dose Conversion Coefficients for Use in Radiological Protection of Embryo and Foetus Against External Exposure to Muons from 20MeV to 50GeV

    SciTech Connect

    Chen Jing

    2008-08-07

    This study used the Monte-Carlo code MCNPX to determine mean absorbed doses to the embryo and foetus when the mother is exposed to external muon fields. Monoenergetic muons ranging from 20 MeV to 50 GeV were considered. The irradiation geometries include anteroposterior (AP), postero-anterior (PA), lateral (LAT), rotational (ROT), isotropic (ISO), and top-down (TOP). At each of these irradiation geometries, absorbed doses to the foetal body were calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months, respectively. Muon fluence-to-absorbed-dose conversion coefficients were derived for the four prenatal ages. Since such conversion coefficients are yet unknown, the results presented here fill a data gap.

  6. [Comparison of the absorbed dose at calibration depth of photon beams using the Japan Society of Medical Physics 12 beam quality conversion factor in the presence or absence of a waterproofing sleeve].

    PubMed

    Kinoshita, Naoki; Takemura, Akihiro; Kita, Akinobu; Murai, Emi; Nishimoto, Yasuhiro; Toi, Akiko; Shimada, Masato; Sasamoto, Kouhei; Adachi, Toshiki

    2013-10-01

    In standard external beam radiotherapy dosimetry, which is based on absorbed dose by water, the absorbed dose at any calibration depth is calculated using the same beam quality conversion factor, regardless of the presence or absence of a waterproofing sleeve. In this study, we evaluated whether there were differences between absorbed doses at calibration depths calculated using a beam quality conversion factor including a wall correction factor that corresponds to a waterproofing sleeve thickness of 0.3 mm, and without a waterproofing sleeve. The Japan Society of Medical Physics (JSMP) has reported that the uncertainty of the results using a beam quality conversion factor that included a wall correction factor corresponding to a waterproofing sleeve thickness of 0.3 mm, regardless of the presence or absence of the sleeve, was 0.2%. This uncertainty proved to be in agreement with the reported range.

  7. PLATIN (plant-atmosphere interaction) I: A model of plant-atmosphere interaction for estimating absorbed doses of gaseous air pollutants.

    PubMed

    Grünhage, L; Haenel, H D

    1997-01-01

    A PLant-ATmosphere INteraction model (PLATIN) was developed for estimating air pollutant absorbed doses under ambient conditions. PLATIN is based on the canopy energy balance combined with a gas transport submodel. The model has three major resistance components: (1) a turbulent atmospheric resistance Rah(zm) that describes the atmospheric transport properties between a measurement height above the canopy and the conceptual height z=d+z0m which represents the sink for momentum according to the big-leaf concept; (2) a quasilaminar layer resistance R(b,A) that quantifies the way in which the transfer of sensible heat and matter (e.g. latent heat, ozone) differs from momentum transfer; (3) a canopy or surface resistance R(c,A) that describes the influences of the plant/soil system on the exchange processes. Soil water content is simulated by a Force-Restore model. By a simple interception submodel precipitation and dew are partitioned into intercepted water and water reaching the soil surface. PLATIN can be run in a prognostic or a diagnostic mode. It is also intended for on-line use in air quality monitoring networks.

  8. Quantifying the Reproducibility of Heart Position During Treatment and Corresponding Delivered Heart Dose in Voluntary Deep Inhalation Breath Hold for Left Breast Cancer Patients Treated With External Beam Radiotherapy

    SciTech Connect

    McIntosh, Alyson; Shoushtari, Asal N.; Benedict, Stanley H.; Read, Paul W.; Wijesooriya, Krishni

    2011-11-15

    Purpose: Voluntary deep inhalation breath hold (VDIBH) reduces heart dose during left breast irradiation. We present results of the first study performed to quantify reproducibility of breath hold using bony anatomy, heart position, and heart dose for VDIBH patients at treatment table. Methods and Materials: Data from 10 left breast cancer patients undergoing VDIBH whole-breast irradiation were analyzed. Two computed tomography (CT) scans, free breathing (FB) and VDIBH, were acquired to compare dose to critical structures. Pretreatment weekly kV orthogonal images and tangential ports were acquired. The displacement difference from spinal cord to sternum across the isocenter between coregistered planning Digitally Reconstructed Radiographs (DRRs) and kV imaging of bony thorax is a measure of breath hold reproducibility. The difference between bony coregistration and heart coregistration was the measured heart shift if the patient is aligned to bony anatomy. Results: Percentage of dose reductions from FB to VDIBH: mean heart dose (48%, SD 19%, p = 0.002), mean LAD dose (43%, SD 19%, p = 0.008), and maximum left anterior descending (LAD) dose (60%, SD 22%, p = 0.008). Average breath hold reproducibility using bony anatomy across the isocenter along the anteroposterior (AP) plane from planning to treatment is 1 (range, 0-3; SD, 1) mm. Average heart shifts with respect to bony anatomy between different breath holds are 2 {+-} 3 mm inferior, 1 {+-} 2 mm right, and 1 {+-} 3 mm posterior. Percentage dose changes from planning to delivery: mean heart dose (7%, SD 6%); mean LAD dose, ((9%, SD 7%)S, and maximum LAD dose, (11%, SD 11%) SD 11%, p = 0.008). Conclusion: We observed excellent three-dimensional bony registration between planning and pretreatment imaging. Reduced delivered dose to heart and LAD is maintained throughout VDIBH treatment.

  9. A water calorimeter for on-site absorbed dose to water calibrations in (60)Co and MV-photon beams including MRI incorporated treatment equipment.

    PubMed

    de Prez, Leon; de Pooter, Jacco; Jansen, Bartel; Aalbers, Tony

    2016-07-01

    In reference dosimetry the aim is to establish the absorbed dose to water, D w, under reference conditions. However, existing dosimetry protocols are not always applicable for rapidly emerging new treatment modalities. For primary standard dosimetry laboratories it is generally not feasible to acquire such modalities. Therefore it is strongly desired that D w measurements with primary standards can be performed on-site in clinical beams for the new treatment modalities in order to characterize and calibrate detectors. To serve this need, VSL has developed a new transportable water calorimeter serving as a primary D w standard for (60)Co and MV-photons including MRI incorporated treatment equipment. Special attention was paid to its operation in different beam geometries and beam modalities including the application in magnetic fields. The new calorimeter was validated in the VSL (60)Co beam and on-site in clinical MV-photon beams. Excellent agreement of 0.1% was achieved with previous (60)Co field calibrations, i.e. well within the uncertainty of the previous calorimeter, and with measurements performed in horizontal and vertical MV-photon beams. k Q factors, determined for two PTW 30013 ionization chambers, agreed very well with available literature data. The relative combined standard uncertainty (k  =  1) for D w measurements in (60)Co and MV-photons is 0.37%. Calibrations are carried out with a standard uncertainty of 0.42% and k Q -factors are determined with a relative standard uncertainty of 0.40%. PMID:27300589

  10. A water calorimeter for on-site absorbed dose to water calibrations in 60Co and MV-photon beams including MRI incorporated treatment equipment

    NASA Astrophysics Data System (ADS)

    de Prez, Leon; de Pooter, Jacco; Jansen, Bartel; Aalbers, Tony

    2016-07-01

    In reference dosimetry the aim is to establish the absorbed dose to water, D w, under reference conditions. However, existing dosimetry protocols are not always applicable for rapidly emerging new treatment modalities. For primary standard dosimetry laboratories it is generally not feasible to acquire such modalities. Therefore it is strongly desired that D w measurements with primary standards can be performed on-site in clinical beams for the new treatment modalities in order to characterize and calibrate detectors. To serve this need, VSL has developed a new transportable water calorimeter serving as a primary D w standard for 60Co and MV-photons including MRI incorporated treatment equipment. Special attention was paid to its operation in different beam geometries and beam modalities including the application in magnetic fields. The new calorimeter was validated in the VSL 60Co beam and on-site in clinical MV-photon beams. Excellent agreement of 0.1% was achieved with previous 60Co field calibrations, i.e. well within the uncertainty of the previous calorimeter, and with measurements performed in horizontal and vertical MV-photon beams. k Q factors, determined for two PTW 30013 ionization chambers, agreed very well with available literature data. The relative combined standard uncertainty (k  =  1) for D w measurements in 60Co and MV-photons is 0.37%. Calibrations are carried out with a standard uncertainty of 0.42% and k Q -factors are determined with a relative standard uncertainty of 0.40%.

  11. Radiation dose delivered to the proximal penis as a predictor of the risk of erectile dysfunction after three-dimensional conformal radiotherapy for localized prostate cancer

    SciTech Connect

    Wernicke, A. Gabriella; Valicenti, Richard . E-mail: richard.valicenti@mail.tju.edu; DiEva, Kelly; Houser, Christopher; Pequignot, Ed

    2004-12-01

    Purpose/objective: In this study, we evaluated in a serial manner whether radiation dose to the bulb of the penis is predictive of erectile dysfunction, ejaculatory difficulty (EJ), and overall satisfaction with sex life (quality of life) by using serial validated self-administered questionnaires. Methods and materials: Twenty-nine potent men with AJCC Stage II prostate cancer treated with three-dimensional conformal radiation therapy alone to a median dose 72.0 Gy (range: 66.6-79.2 Gy) were evaluated by determining the doses received by the penile bulb. The penile bulb was delineated volumetrically, and the dose-volume histogram was obtained on each patient. Results: The median follow-up time was 35 months (range, 16-43 months). We found that for D{sub 30}, D{sub 45}, D{sub 60}, and D{sub 75} (doses to a percent volume of PB: 30%, 45%, 60%, and 75%), higher than the corresponding median dose (defined as high-dose group) correlated with an increased risk of impotence (erectile dysfunction firmness score = 0) (odds ratio [OR] = 7.5, p = 0.02; OR = 7.5, p = 0.02; OR = 8.6, p = 0.008; and OR = 6.9, p = 0.015, respectively). Similarly, for EJD D{sub 30}, D{sub 45}, D{sub 60}, and D{sub 75}, doses higher than the corresponding median ones correlated with worsening ejaculatory function score (EJ = 0 or 1) (OR = 8, p = 0.013; OR = 8, p 0.013; OR = 9.2, p = 0.015; and OR = 8, p = 0.026, respectively). For quality of life, low ({<=}median dose) dose groups of patients improve over time, whereas high-dose groups of patients worsen. Conclusions: This study supports the existence of a penile bulb dose-volume relationship underlying the development of radiation-induced erectile dysfunction. Our data may guide the use of inverse treatment planning to maximize the probability of maintaining sexual potency after radiation therapy.

  12. Measuring uncertainty in dose delivered to the cochlea due to setup error during external beam treatment of patients with cancer of the head and neck

    SciTech Connect

    Yan, M.; Lovelock, D.; Hunt, M.; Mechalakos, J.; Hu, Y.; Pham, H.; Jackson, A.

    2013-12-15

    Purpose: To use Cone Beam CT scans obtained just prior to treatments of head and neck cancer patients to measure the setup error and cumulative dose uncertainty of the cochlea. Methods: Data from 10 head and neck patients with 10 planning CTs and 52 Cone Beam CTs taken at time of treatment were used in this study. Patients were treated with conventional fractionation using an IMRT dose painting technique, most with 33 fractions. Weekly radiographic imaging was used to correct the patient setup. The authors used rigid registration of the planning CT and Cone Beam CT scans to find the translational and rotational setup errors, and the spatial setup errors of the cochlea. The planning CT was rotated and translated such that the cochlea positions match those seen in the cone beam scans, cochlea doses were recalculated and fractional doses accumulated. Uncertainties in the positions and cumulative doses of the cochlea were calculated with and without setup adjustments from radiographic imaging. Results: The mean setup error of the cochlea was 0.04 ± 0.33 or 0.06 ± 0.43 cm for RL, 0.09 ± 0.27 or 0.07 ± 0.48 cm for AP, and 0.00 ± 0.21 or −0.24 ± 0.45 cm for SI with and without radiographic imaging, respectively. Setup with radiographic imaging reduced the standard deviation of the setup error by roughly 1–2 mm. The uncertainty of the cochlea dose depends on the treatment plan and the relative positions of the cochlea and target volumes. Combining results for the left and right cochlea, the authors found the accumulated uncertainty of the cochlea dose per fraction was 4.82 (0.39–16.8) cGy, or 10.1 (0.8–32.4) cGy, with and without radiographic imaging, respectively; the percentage uncertainties relative to the planned doses were 4.32% (0.28%–9.06%) and 10.2% (0.7%–63.6%), respectively. Conclusions: Patient setup error introduces uncertainty in the position of the cochlea during radiation treatment. With the assistance of radiographic imaging during setup

  13. Total body irradiation must be delivered at high dose for efficient engraftment and tolerance in a rhesus stem cell gene therapy model

    PubMed Central

    Uchida, Naoya; Weitzel, R Patrick; Shvygin, Anna; Skala, Luke P; Raines, Lydia; Bonifacino, Aylin C; Krouse, Allen E; Metzger, Mark E; Donahue, Robert E; Tisdale, John F

    2016-01-01

    Reduced intensity conditioning (RIC) is desirable for hematopoietic stem cell (HSC) gene therapy applications. However, low gene marking was previously observed in gene therapy trials, suggesting that RIC might be insufficient for (i) opening niches for efficient engraftment and/or (ii) inducing immunological tolerance for transgene-encoded proteins. Therefore, we evaluated both engraftment and tolerance for gene-modified cells using our rhesus HSC gene therapy model following RIC. We investigated a dose de-escalation of total body irradiation (TBI) from our standard dose of 10Gy (10, 8, 6, and 4Gy), in which rhesus CD34+ cells were transduced with a VSVG-pseudotyped chimeric HIV-1 vector encoding enhanced green fluorescent protein (GFP) (or enhanced yellow fluorescent protein (YFP)). At ~6 months after transplantation, higher-dose TBI resulted in higher gene marking with logarithmic regression in peripheral blood cells. We then evaluated immunological tolerance for gene-modified cells, and found that lower-dose TBI allowed vigorous anti-GFP antibody production with logarithmic regression, while no significant anti-VSVG antibody formation was observed among all TBI groups. These data suggest that higher-dose TBI improves both engraftment and immunological tolerance for gene-modified cells. Additional immunosuppression might be required in RIC to induce tolerance for transgene products. Our findings should be valuable for developing conditioning regimens for HSC gene therapy applications.

  14. Total body irradiation must be delivered at high dose for efficient engraftment and tolerance in a rhesus stem cell gene therapy model.

    PubMed

    Uchida, Naoya; Weitzel, R Patrick; Shvygin, Anna; Skala, Luke P; Raines, Lydia; Bonifacino, Aylin C; Krouse, Allen E; Metzger, Mark E; Donahue, Robert E; Tisdale, John F

    2016-01-01

    Reduced intensity conditioning (RIC) is desirable for hematopoietic stem cell (HSC) gene therapy applications. However, low gene marking was previously observed in gene therapy trials, suggesting that RIC might be insufficient for (i) opening niches for efficient engraftment and/or (ii) inducing immunological tolerance for transgene-encoded proteins. Therefore, we evaluated both engraftment and tolerance for gene-modified cells using our rhesus HSC gene therapy model following RIC. We investigated a dose de-escalation of total body irradiation (TBI) from our standard dose of 10Gy (10, 8, 6, and 4Gy), in which rhesus CD34(+) cells were transduced with a VSVG-pseudotyped chimeric HIV-1 vector encoding enhanced green fluorescent protein (GFP) (or enhanced yellow fluorescent protein (YFP)). At ~6 months after transplantation, higher-dose TBI resulted in higher gene marking with logarithmic regression in peripheral blood cells. We then evaluated immunological tolerance for gene-modified cells, and found that lower-dose TBI allowed vigorous anti-GFP antibody production with logarithmic regression, while no significant anti-VSVG antibody formation was observed among all TBI groups. These data suggest that higher-dose TBI improves both engraftment and immunological tolerance for gene-modified cells. Additional immunosuppression might be required in RIC to induce tolerance for transgene products. Our findings should be valuable for developing conditioning regimens for HSC gene therapy applications. PMID:27652288

  15. Total body irradiation must be delivered at high dose for efficient engraftment and tolerance in a rhesus stem cell gene therapy model

    PubMed Central

    Uchida, Naoya; Weitzel, R Patrick; Shvygin, Anna; Skala, Luke P; Raines, Lydia; Bonifacino, Aylin C; Krouse, Allen E; Metzger, Mark E; Donahue, Robert E; Tisdale, John F

    2016-01-01

    Reduced intensity conditioning (RIC) is desirable for hematopoietic stem cell (HSC) gene therapy applications. However, low gene marking was previously observed in gene therapy trials, suggesting that RIC might be insufficient for (i) opening niches for efficient engraftment and/or (ii) inducing immunological tolerance for transgene-encoded proteins. Therefore, we evaluated both engraftment and tolerance for gene-modified cells using our rhesus HSC gene therapy model following RIC. We investigated a dose de-escalation of total body irradiation (TBI) from our standard dose of 10Gy (10, 8, 6, and 4Gy), in which rhesus CD34+ cells were transduced with a VSVG-pseudotyped chimeric HIV-1 vector encoding enhanced green fluorescent protein (GFP) (or enhanced yellow fluorescent protein (YFP)). At ~6 months after transplantation, higher-dose TBI resulted in higher gene marking with logarithmic regression in peripheral blood cells. We then evaluated immunological tolerance for gene-modified cells, and found that lower-dose TBI allowed vigorous anti-GFP antibody production with logarithmic regression, while no significant anti-VSVG antibody formation was observed among all TBI groups. These data suggest that higher-dose TBI improves both engraftment and immunological tolerance for gene-modified cells. Additional immunosuppression might be required in RIC to induce tolerance for transgene products. Our findings should be valuable for developing conditioning regimens for HSC gene therapy applications. PMID:27652288

  16. 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

  17. Comparison of Planned Versus Actual Dose Delivered for External Beam Accelerated Partial Breast Irradiation Using Cone-Beam CT and Deformable Registration

    SciTech Connect

    Hasan, Yasmin; Kim, Leonard; Wloch, Jennifer; Chi, Y.; Liang, J.; Martinez, Alvaro; Yan Di; Vicini, Frank

    2011-08-01

    Purpose: To assess the adequacy of dose delivery to the clinical target volume (CTV) using external beam (EB) accelerated partial breast irradiation (APBI). Methods and Materials: Sixteen patients treated with EB APBI underwent cone beam CT (CBCT) before each fraction and daily helical CT (HCT) scans to determine setup errors and calculate the dose per fraction. For 12 patients, an in-house image-intensity-based deformable registration program was used to register the HCTs to the planning CT and generate the cumulative dose. Treatment was 38.5 Gy in 10 fractions. EB APBI constraints from the National Surgical Adjuvant Breast and Bowel Project B39/Radiation Therapy Oncology Group 0413 Phase III protocol were used. Results: The mean setup error per CBCT registration was 9 {+-} 5 mm. Dose-volume histogram analysis showed only one patient (8%) with a decrease in the CTV V90 (8% underdosage). All other patients demonstrated adequate target coverage. PTV{sub E}VAL V90 was on average 3% (range, 0%-16%) less than planned. For the ipsilateral breast, four patients had an increase in V50 ({<=}1% increase) and three patients had an increase in V100 ({<=}9% increase). Only one patient showed an increase >5%. Four patients had an increase in ipsilateral lung V30 (maximum 3%), and one had an increase in heart V5 (1%). Four patients had an increase in MaxDose (maximum 89 cGy). Conclusions: The current CTV-to-PTV margin of 10 mm appears sufficient for {approx}92% of patients treated with EB APBI. Although expansion of the population PTV margin to 14 mm would provide {approx}97% confidence level for CTV coverage, online image guidance should be considered.

  18. Radiation dose descriptors: BERT, COD, DAP, and other strange creatures.

    PubMed

    Nickoloff, Edward L; Lu, Zheng Feng; Dutta, Ajoy K; So, James C

    2008-01-01

    Over the years, a number of terms have been used to describe radiation dose. Eight common radiation dose descriptors include background equivalent radiation time (BERT), critical organ dose (COD), surface absorbed dose (SAD), dose area product (DAP), diagnostic acceptable reference level (DARLing), effective dose (ED), fetal absorbed dose (FAD), and total imparted energy (TIE). BERT is compared to the annual natural background radiation (about 3 mSv per year) and is easily understandable for the general public. COD refers to the radiation dose delivered to an individual critical organ. SAD is the radiation dose delivered at the skin surface. DAP is a product of the irradiated surface area multiplied by the radiation dose at the surface. DARLing is usually the radiation level that encompasses 75% (the third quartile) of the data derived from a nationwide or regional survey. DARLings are meant for voluntary guidance. Consistently higher patient doses should be investigated for possible equipment deficiencies or suboptimal protocols. ED is obtained by multiplying the radiation dose delivered to each organ by its weighting factor and then by adding those values to get the sum. It can be used to assess the risk of radiation-induced cancers and serious hereditary effects to future generations, regardless of the procedure being performed, and is the most useful radiation dose descriptor. FAD is the radiation dose delivered to the fetus, and TIE is the sum of the energy imparted to all irradiated tissue. Each of these descriptors is intended to relate radiation dose ultimately to potential biologic effects. To avoid confusion, the key is to avoid using the terms interchangeably. It is important to understand each of the radiation dose descriptors and their derivation in order to correctly evaluate radiation dose and to consult with patients concerned about the risks of radiation.

  19. LESM: a laser-driven sub-MeV electron source delivering ultra-high dose rate on thin biological samples

    NASA Astrophysics Data System (ADS)

    Labate, L.; Andreassi, M. G.; Baffigi, F.; Bizzarri, R.; Borghini, A.; Bussolino, G. C.; Fulgentini, L.; Ghetti, F.; Giulietti, A.; Köster, P.; Lamia, D.; Levato, T.; Oishi, Y.; Pulignani, S.; Russo, G.; Sgarbossa, A.; Gizzi, L. A.

    2016-07-01

    We present a laser-driven source of electron bunches with average energy 260~\\text{keV} and picosecond duration, which has been setup for radiobiological tests covering the previously untested sub-MeV energy range. Each bunch combines high charge with short duration and sub-millimeter range into a record instantaneous dose rate, as high as {{10}9}~\\text{Gy}~{{\\text{s}}-1} . The source can be operated at 10~\\text{Hz} and its average dose rate is 35~\\text{mGy}~{{\\text{s}}-1} . Both the high instantaneous dose rate and high level of relative biological effectiveness, attached to sub-MeV electrons, make this source very attractive for studies of ultrafast radiobiology on thin cell samples. The source reliability, in terms of shot-to-shot stability of features such as mean energy, bunch charge and transverse beam profile, is discussed, along with a dosimetric characterization. Finally, a few preliminary biological tests performed with this source are presented.

  20. SU-E-P-55: The Reaserch of Cervical Cancer Delivered with Constant Dose Rate and Gantry Speed Arc Therapy(CDR-CAS-IMAT) On Conventional Linac

    SciTech Connect

    Zhang, R; Bai, W; Chi, Z; Gao, C; Xiaomei, F; Gao, Y

    2015-06-15

    Purpose: Postoperative cervical cancer patients with large target volume and the target shape is concave, treatmented with static intensity-modulated radiotherapy (IMRT) is time consuming. The purpose of this study is to investigate using constant dose rate and gantry speed arc therapy(CDR-CAS-IMAT) on conventional linear accelrator, by comparing with the IMRT technology to evaluate the performance of CDR-CAS-IMAT on postoperative cervical cancer patients. Methods: 18 cervical cancer patients treated with IMRT on Varian 23IX were replanted using CDR-CAS-IMAT. The plans were generated on Oncentra v4.1 planning system, PTV was prescribed to 50.4 Gy in 28 fractions. Plans were evaluated based on the ability to meet the dose volume histogram. The homogeneity index (HI), conformity index (CI) of target volume, the dose of organs at risk, radiation delivery time and monitor units were also compared. SPSS 19.0 software paired T-test analysis was carried out on the two sets of data. Results: Compared with the IMRT plans PTV’s CI (t= 3.85, P =0.001), CTV’s CI, HI, D90, D95, D98, V95, V98, V100 (t=4.21, −3.18, 2.13, 4.65, 7.79, 2.29, 6.00, 2.13, p=0.001, 0.005, 0.049, 0.000, 0.000, 0.035, 0.000, 0.049), and cord D2 and rectum V40 (t=−2.65, −2.47, p= P =0.017, 0.025), and treatment time and MU (t=−36.0, −6.26, P =0.000, 0.000) were better than that of IMRT group. But the IMRT plans in terms of decreasing bladder V50, bowel V30 (t=2.14, 3.00, P =0.048, 0.008) and low dose irradiation volume were superior to that of CDR-CAS-IMAT plans. There were no significant differences in other statistical index. Conclusion: Cervical cancer patients with CDR-CAS-IMAT on Varian Clinical 23IX can get equivalent or superior dose distribution compared with the IMRT technology. IMAT have much less treatment time and MU can reduce the uncertainty factor and patient discomfort in treatment. This work was supported by the Medical Science Foundation of the health department of Hebei

  1. Sound Absorbers

    NASA Astrophysics Data System (ADS)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  2. Data on biodistribution and radiation absorbed dose profile of a novel (64)Cu-labeled high affinity cell-specific peptide for positron emission tomography imaging of tumor vasculature.

    PubMed

    Merrill, Joseph R; Krajewski, Krzysztof; Yuan, Hong; Frank, Jonathan E; Lalush, David S; Patterson, Cam; Veleva, Anka N

    2016-06-01

    New peptide-based diagnostic and therapeutic approaches hold promise for highly selective targeting of cancer leading to more precise and effective diagnostic and therapeutic modalities. An important feature of these approaches is to reach the tumor tissue while limiting or minimizing the dose to normal organs. In this context, efforts to design and engineer materials with optimal in vivo targeting and clearance properties are important. This Data In Brief article reports on biodistribution and radiation absorbed dose profile of a novel high affinity radiopeptide specific for bone marrow-derived tumor vasculature. Background information on the design, preparation, and in vivo characterization of this peptide-based targeted radiodiagnostic is described in the article "Synthesis and comparative evaluation of novel 64Cu-labeled high affinity cell-specific peptides for positron emission tomography of tumor vasculature" (Merrill et al., 2016) [1]. Here we report biodistribution measurements in mice and calculate the radiation absorbed doses to normal organs using a modified Medical Internal Radiation Dosimetry (MIRD) methodology that accounts for physical and geometric factors and cross-organ beta doses. PMID:27014735

  3. Fluence-to-absorbed-dose conversion coefficients for neutron beams from 0.001 eV to 100 GeV calculated for a set of pregnant female and fetus models

    NASA Astrophysics Data System (ADS)

    Taranenko, Valery; Xu, X. George

    2008-03-01

    Protection of fetuses against external neutron exposure is an important task. This paper reports a set of absorbed dose conversion coefficients for fetal and maternal organs for external neutron beams using the RPI-P pregnant female models and the MCNPX code. The newly developed pregnant female models represent an adult female with a fetus including its brain and skeleton at the end of each trimester. The organ masses were adjusted to match the reference values within 1%. For the 3 mm cubic voxel size, the models consist of 10-15 million voxels for 35 organs. External monoenergetic neutron beams of six standard configurations (AP, PA, LLAT, RLAT, ROT and ISO) and source energies 0.001 eV-100 GeV were considered. The results are compared with previous data that are based on simplified anatomical models. The differences in dose depend on source geometry, energy and gestation periods: from 20% up to 140% for the whole fetus, and up to 100% for the fetal brain. Anatomical differences are primarily responsible for the discrepancies in the organ doses. For the first time, the dependence of mother organ doses upon anatomical changes during pregnancy was studied. A maximum of 220% increase in dose was observed for the placenta in the nine months model compared to three months, whereas dose to the pancreas, small and large intestines decreases by 60% for the AP source for the same models. Tabulated dose conversion coefficients for the fetus and 27 maternal organs are provided.

  4. Impact of High-Dose Chemotherapy on The Ability to Deliver Subsequent Local–Regional Radiotherapy for Breast Cancer: Analysis of Cancer and Leukemia Group B Protocol 9082

    PubMed Central

    Marks, Lawrence B.; Cirrincione, Constance; Fitzgerald, Thomas J.; Laurie, Frances; Glicksman, Arvin S.; Vredenburgh, James; Prosnitz, Leonard R.; Shpall, Elizabeth J.; Crump, Michael; Richardson, Paul G.; Schuster, Michael W.; Ma, Jinli; Peterson, Bercedis L.; Norton, Larry; Seagren, Steven; Henderson, I. Craig; Hurd, David D.; Peters, William P.

    2009-01-01

    Purpose To report, from Cancer and Leukemia Group B Protocol 9082, the impact of high-dose cyclophosphamide, cisplatin, and BCNU (HD-CPB) vs. intermediate-dose CPB (ID-CPB) on the ability to start and complete the planned course of local–regional radiotherapy (RT) for women with breast cancer involving ≥10 axillary nodes. Methods and Materials From 1991 to 1998, 785 patients were randomized. The HD-CPB and ID-CPB arms were balanced regarding patient characteristics. The HD-CPB and ID-CPB arms were compared on the probability of RT initiation, interruption, modification, or incompleteness. The impact of clinical variables and interactions between variables were also assessed. Results Radiotherapy was initiated in 82% (325 of 394) of HD-CPB vs. 92% (360 of 391) of ID-CPB patients (p = 0.001). On multivariate analyses, RT was less likely given to patients who were randomized to HD treatment (odds ratio [OR] = 0 .38, p < 0.001), older (p = 0.005), African American (p = 0.003), postmastectomy (p = 0.02), or estrogen receptor positive (p = 0.03). High-dose treatment had a higher rate of RT interruption (21% vs. 12%, p = 0.001, OR = 2.05), modification (29% vs. 14%, p = 0.001, OR = 2.46), and early termination of RT (9% vs. 2%, p = 0.0001, OR = 5.35), compared with ID. Conclusion Treatment arm significantly related to initiation, interruption, modification, and early termination of RT. Patients randomized to HD-CPB were less likely to initiate RT, and of those who did, they were more likely to have RT interrupted, modified, and terminated earlier than those randomized to ID-CPB. The observed lower incidence of RT usage in African Americans vs. non–African Americans warrants further study. PMID:19747781

  5. Impact of High-Dose Chemotherapy on the Ability to Deliver Subsequent Local-Regional Radiotherapy for Breast Cancer: Analysis of Cancer and Leukemia Group B Protocol 9082

    SciTech Connect

    Marks, Lawrence B.; Cirrincione, Constance M.S.; Fitzgerald, Thomas J.; Laurie, Frances; Glicksman, Arvin S.; Vredenburgh, James; Prosnitz, Leonard R.; Shpall, Elizabeth J.; Crump, Michael; Richardson, Paul G.; Schuster, Michael W.; Ma Jinli; Peterson, Bercedis L.; Norton, Larry; Seagren, Steven

    2010-04-15

    Purpose: To report, from Cancer and Leukemia Group B Protocol 9082, the impact of high-dose cyclophosphamide, cisplatin, and BCNU (HD-CPB) vs. intermediate-dose CPB (ID-CPB) on the ability to start and complete the planned course of local-regional radiotherapy (RT) for women with breast cancer involving >=10 axillary nodes. Methods and Materials: From 1991 to 1998, 785 patients were randomized. The HD-CPB and ID-CPB arms were balanced regarding patient characteristics. The HD-CPB and ID-CPB arms were compared on the probability of RT initiation, interruption, modification, or incompleteness. The impact of clinical variables and interactions between variables were also assessed. Results: Radiotherapy was initiated in 82% (325 of 394) of HD-CPB vs. 92% (360 of 391) of ID-CPB patients (p = 0.001). On multivariate analyses, RT was less likely given to patients who were randomized to HD treatment (odds ratio [OR] = 0 .38, p < 0.001), older (p = 0.005), African American (p = 0.003), postmastectomy (p = 0.02), or estrogen receptor positive (p = 0.03). High-dose treatment had a higher rate of RT interruption (21% vs. 12%, p = 0.001, OR = 2.05), modification (29% vs. 14%, p = 0.001, OR = 2.46), and early termination of RT (9% vs. 2%, p = 0.0001, OR = 5.35), compared with ID. Conclusion: Treatment arm significantly related to initiation, interruption, modification, and early termination of RT. Patients randomized to HD-CPB were less likely to initiate RT, and of those who did, they were more likely to have RT interrupted, modified, and terminated earlier than those randomized to ID-CPB. The observed lower incidence of RT usage in African Americans vs. non-African Americans warrants further study.

  6. Study of radiation effects on the cell structure and evaluation of the dose delivered by x-ray and {alpha}-particles microscopy

    SciTech Connect

    Kosior, Ewelina; Cloetens, Peter; Deves, Guillaume; Ortega, Richard; Bohic, Sylvain

    2012-12-24

    Hard X-ray fluorescence microscopy and magnified phase contrast imaging are combined to study radiation effects on cells. Experiments were performed on freeze-dried cells at the nano-imaging station ID22NI of the European synchrotron radiation facility. Quantitative phase contrast imaging provides maps of the projected mass and is used to evaluate the structural changes due to irradiation during X-ray fluorescence experiments. Complementary to phase contrast imaging, scanning transmission ion microscopy is performed and doses of all the experiments are compared. We demonstrate the sensitivity of the proposed approach to study radiation-induced damage at the sub-cellular level.

  7. Radionuclide characterization and associated dose from long-lived radionuclides in close-in fallout delivered to the marine environment at Bikini and Enewetak Atolls.

    PubMed

    Robison, W L; Noshkin, V E

    1999-09-30

    Between June 1946 and October 1958, Enewetak and Bikini Atolls were used by the US as testing grounds for 66 nuclear devices. The combined explosive yield from these tests was 107 million t (million t TNT equivalents). This testing produced close-in fallout debris that was contaminated with quantities of radioactive fission and particle activated products, and unspent radioactive nuclear fuel that entered the aquatic environment of the atolls. Today, the sediments in the lagoons are reservoirs for tens of TBq of the transuranics and some long-lived fission and activation products. The larger amounts of contamination are associated with fine and coarse sediment material adjacent to the locations of the high yield explosions. Radionuclides are also distributed vertically in the sediment column to various depths in all regions of the lagoons. Concentrations greater than fallout background levels are found in filtered water sampled over several decades from all locations and depths in the lagoons. This is a direct indication that the radionuclides are continuously mobilized to solution from the solid phases. Of particular importance is the fact that the long-lived radionuclides are accumulated to different levels by indigenous aquatic plants and organisms that are used as food by resident people. One might anticipate finding continuous high contamination levels in many of the edible marine organisms from the lagoons, since the radionuclides associated with the sediments are not contained and are available to the different organisms in a relatively shallow water environment. This is not the case. We estimate that the radiological dose from consumption of the edible parts of marine foods at Enewetak and Bikini is presently approximately 0.05% of the total 50-year integral effective dose from all other exposure pathways that include ingestion of terrestrial foods and drinking water, external exposure and inhalation. The total radiological dose from the marine pathway is

  8. Radionuclide characterization and associated dose from long-lived radionuclides in close-in fallout delivered to the marine environment at Bikini and Enewetak Atoll

    SciTech Connect

    Noshkin, V. E.; Robison, W. L.

    1998-09-01

    Between June 1946 and October 1958, Enewetak and Bikini Atolls were used by the United States as testing grounds for 66 nuclear devices. The combined explosive yield from these tests was 107 Mt (Mt TNT equivalents). This testing produced close-in fallout debris that was contaminated with quantities of radioactive fission and particle activated products, and unspent radioactive nuclear fuel that entered the aquatic environment of the atolls. Today, the sediments in the lagoons are reservoirs for 10's of TBq of the transuranics and some long-lived fission and activation products. The larger amounts of contamination are associated with fine and coarse sediment material adjacent to the locations of the high yield explosions. Radionuclides are also distributed vertically in the sediment column to various depths in all regions of the lagoons. Concentrations greater than fallout background levels are found in filtered water sampled over several decades from all locations and depths in the lagoons. This is a direct indication that the radionuclides are continuously mobilized to solution from the solid phases. Of particular importance is the fact that the long-lived radionuclides are accumulated to different levels by indigenous aquatic plants and organisms that are used as food by resident people. One might anticipate finding continuous high contamination levels in many of the edible marine organisms from the lagoons, since the radionuclides associated with the sediments are not contained and are available to the different organisms in a relatively shallow water environment. This is not the case. We estimate that the radiological dose from consumption of the edible parts of marine foods at Enewetak and Bikini is presently about 0.05% of the total 50-year integral effective dose from all other exposure pathways that include ingestion of terrestrial foods and drinking water, external exposure and inhalation. The total radiological dose from the marine pathway is dominated by

  9. TH-C-BRD-08: Reducing the Effect of Respiratory Motion On the Delivered Dose in Proton Therapy Through Proper Field Angle Selection

    SciTech Connect

    Matney, J; Park, P; Court, L; Zhu, X; Li, H; Mohan, R; Liu, W; Dong, L

    2014-06-15

    Purpose: This work investigated a novel planning strategy of selecting radiotherapy beam angles that minimizes the change in water equivalent thickness (dWET) during respiration in order to reduce the effects of respiratory motion in passively scattered proton therapy (PSPT). Methods: In a clinical trial treating locally-advanced lung cancer with proton therapy, 2–4 co-planar beams were previously selected by dosimetrists in the design of physician-approved PSPT treatment plans. The authors identified a cohort of patients in which respiratory motion affected the planned PSPT dose delivery. For this cohort, this work analyzed dWET during respiration over a 360 degree arc of potential treatment angles around the patient: the dWET was defined as the difference in WET between the full-exhale (T50) and full-inhale (T0) phases of the simulation 4DCT. New PSPT plans were redesigned by selecting new beam angles that demonstrated significant reduction in the value of dWET. Between the T50 and T0 phases, the root-mean-square deviation of dose and the change in dose-volume histogram curves (dAUC) for anatomical structures were calculated to compare the original to dWET reduction plans. Results: To date, three plans were retrospectively redesigned based on dWET analysis. In the dWET reduction plan, the root mean square dose (T50-T0) was reduced by 15–35% and the DVH dAUC values were reduced by more than 60%.The PSPT plans redesigned by selecting appropriate field angles to minimize dWET demonstrated less dosimetric variation due to respiration. Conclusion: We have introduced the use of a new metric to quantify respiratory motion in proton therapy: dWET. The use of dWET allows us to minimize the impact of respiratory motion of the entire anatomy in the beam path. This work is a proof of principle that dWET could suggest field angles in proton therapy that are more robust to the effects of respiratory motion.

  10. Effect of Infant Formula Containing a Low Dose of the Probiotic Bifidobacterium lactis CNCM I-3446 on Immune and Gut Functions in C-Section Delivered Babies: A Pilot Study

    PubMed Central

    Baglatzi, L.; Gavrili, S.; Stamouli, K.; Zachaki, S.; Favre, L.; Pecquet, S.; Benyacoub, J.; Costalos, C.

    2016-01-01

    BACKGROUND In the absence of breast-feeding and its immunomodulatory factors, supplementation of starter infant formula (IF) with probiotics is currently used to support immune functions and gut development. AIM To assess whether immune-related beneficial effects of regular dose (107 CFU/g of powder) of the probiotic Bifidobacterium lactis CNCM I-3446 (hereafter named B. lactis) in starter IF supplementation can be maintained with starter IF containing a low dose (104 CFU/g of powder) of B. lactis. METHOD This trial was designed as a pilot, prospective, double-blind, randomized, single-center clinical trial of two parallel groups (n = 77 infants/group) of C-section delivered infants receiving a starter IF containing either low dose or regular dose of the probiotic B. lactis from birth to six months of age. In addition, a reference group of infants breast-fed for a minimum of four months (n = 44 infants), also born by C-section, were included. All groups were then provided follow-up formula without B. lactis up to 12 months of age. Occurrence of diarrhea, immune and gut maturation, responses to vaccinations, and growth were assessed from birth to 12 months. The effect of low-dose B. lactis formula was compared to regular-dose B. lactis formula, considered as reference for IF with probiotics, and both were further compared to breast-feeding as a physiological reference. RESULTS Data showed that feeding low-dose B. lactis IF provides similar effects as feeding regular-dose B. lactis IF or breast milk. No consistent statistical differences regarding early life protection against gastrointestinal infections, immune and gut maturation, microbiota establishment, and growth were observed between randomized formula-fed groups as well as with the breast-fed reference group. CONCLUSION This pilot study suggests that supplementing C-section born neonates with low-dose B. lactis-containing starter formula may impact immune as well as gut maturation similarly to regular-dose B

  11. Comparison of internal doses calculated using the specific absorbed fractions of the average adult Japanese male phantom with those of the reference computational phantom-adult male of ICRP publication 110

    NASA Astrophysics Data System (ADS)

    Manabe, Kentaro; Sato, Kaoru; Endo, Akira

    2014-03-01

    In order to study the effects of body sizes and masses of organs and tissues on internal dose assessment, the values corresponding to effective dose coefficients for intakes of radionuclides were calculated using the specific absorbed fractions (SAFs) of two phantoms: the average adult Japanese male phantom (JM-103) and the reference computational phantom-adult male (RCP-AM) of the International Commission on Radiological Protection. SAFs were evaluated using the phantoms and Monte Carlo radiation transport code MCNPX or were taken from published data. As a result of a comparison for 2894 cases of 923 radionuclides, the maximum discrepancy in the effective dose coefficients between the JM-103 and RCP-AM was about 40%. However, the discrepancies were smaller than 10% in 97% of all cases.

  12. Peripheral dose measurements with diode and thermoluminescence dosimeters for intensity modulated radiotherapy delivered with conventional and un-conventional linear accelerator.

    PubMed

    Kinhikar, Rajesh; Gamre, Poonam; Tambe, Chandrashekhar; Kadam, Sudarshan; Biju, George; Suryaprakash; Magai, C S; Dhote, Dipak; Shrivastava, Shyam; Deshpande, Deepak

    2013-01-01

    The objective of this paper was to measure the peripheral dose (PD) with diode and thermoluminescence dosimeter (TLD) for intensity modulated radiotherapy (IMRT) with linear accelerator (conventional LINAC), and tomotherapy (novel LINAC). Ten patients each were selected from Trilogy dual-energy and from Hi-Art II tomotherapy. Two diodes were kept at 20 and 25 cm from treatment field edge. TLDs (LiF:MgTi) were also kept at same distance. TLDs were also kept at 5, 10, and 15 cm from field edge. The TLDs were read with REXON reader. The readings at the respective distance were recorded for both diode and TLD. The PD was estimated by taking the ratio of measured dose at the particular distance to the prescription dose. PD was then compared with diode and TLD for LINAC and tomotherapy. Mean PD for LINAC with TLD and diode was 2.52 cGy (SD 0.69), 2.07 cGy (SD 0.88) at 20 cm, respectively, while at 25 cm, it was 1.94 cGy (SD 0.58) and 1.5 cGy (SD 0.75), respectively. Mean PD for tomotherapy with TLD and diode was 1.681 cGy SD 0.53) and 1.58 (SD 0.44) at 20 cm, respectively. The PD was 1.24 cGy (SD 0.42) and 1.088 cGy (SD 0.35) at 25 cm, respectively, for tomotherapy. Overall, PD from tomotherapy was found lower than LINAC by the factor of 1.2-1.5. PD measurement is essential to find out the potential of secondary cancer. PD for both (conventional LINAC) and novel LINACs (tomotherapy) were measured and compared with each other. The comparison of the values for PD presented in this work and those published in the literature is difficult because of the different experimental conditions. The diode and TLD readings were reproducible and both the detector readings were comparable.

  13. 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.

  14. Immune response elicited by an intranasally delivered HBsAg low-dose adsorbed to poly-ε-caprolactone based nanoparticles.

    PubMed

    Jesus, Sandra; Soares, Edna; Costa, João; Borchard, Gerrit; Borges, Olga

    2016-05-17

    Among new strategies to increase hepatitis B virus (HBV) vaccination, especially in developing countries, the development of self-administered vaccines is considered one of the most valuable. Nasal vaccination using polymeric nanoparticles (NPs) constitutes a valid approach to this issue. In detail, poly-ε-caprolactone (PCL)/chitosan NPs present advantages as a mucosal vaccine delivery system: the high resistance of PCL against degradation in biological fluids and the mucoadhesive and immunostimulatory properties of chitosan. In vitro studies revealed these NPs were retained in a mucus-secreting pulmonary epithelial cell line and were capable of entering into differentiated epithelial cells. The intranasal (IN) administration of 3 different doses of HBsAg (1.5 μg, 5 μg and 10 μg) adsorbed on a fixed amount of PCL/chitosan NPs (1614 μg) generated identical titers of serum anti-HBsAg IgG and anti-HBsAg sIgA in mice nasal secretions. Besides other factors, the NP surface characteristics, particularly, zeta potential differences among the administered formulations are believed to be implicated in the outcome of the immune response generated.

  15. Influence of carrier cells on the clinical outcome of children with neuroblastoma treated with high dose of oncolytic adenovirus delivered in mesenchymal stem cells.

    PubMed

    Melen, Gustavo J; Franco-Luzón, Lidia; Ruano, David; González-Murillo, África; Alfranca, Arantzazu; Casco, Fernando; Lassaletta, Álvaro; Alonso, Mercedes; Madero, Luís; Alemany, Ramón; García-Castro, Javier; Ramírez, Manuel

    2016-02-28

    We report here our clinical experience of a program of compassionate use of Celyvir--autologous marrow-derived mesenchymal stem cells (MSCs) carrying an oncolytic adenovirus--for treating children with advanced metastatic neuroblastoma. Children received weekly doses of Celyvir with no concomitant treatments. The tolerance was excellent, with very mild and self-limited viral-related symptoms. Patients could be distinguished based on their response to therapy: those who had a clinical response (either complete, partial or stabilization) and those who did not respond. We found differences between patients who responded versus those who did not when analyzing their respective MSCs, at the expression levels of adhesion molecules (CCR1, CXCR1 and CXCR4) and in migration capacities in transwell assays, and in immune-related molecules (IFNγ, HLA-DR). These results suggest interpatient differences in the homing and immune modulation capacities of the therapy administered. In addition, the pretherapy immune T cell status and the T effector response were markedly different between responders and non-responders. We conclude that multidoses of Celyvir have an excellent safety profile in children with metastatic neuroblastoma. Intrinsic patients' and MSCs' factors appear to be related to clinical outcome.

  16. Comparison of gamma scintigraphy and a pharmacokinetic technique for assessing pulmonary deposition of terbutaline sulphate delivered by pressurized metered dose inhaler.

    PubMed

    Newman, S; Steed, K; Hooper, G; Källén, A; Borgström, L

    1995-02-01

    A comparison has been made of pulmonary deposition of terbutaline sulphate from a pressurized metered dose inhaler (pMDI), measured in 8 healthy male subjects by gamma scintigraphy and by a pharmacokinetic (charcoal-block) method, involving drug recovery in urine. Measurements were carried out with a pMDI at slow (27 l/min) and fast (151 l/min) inhaled flows and with Nebuhaler large volume spacer device (average inhaled flow 17 l/min). Overall, the two methods did not differ significantly in their estimates of whole lung deposition, although values obtained by gamma scintigraphy exceeded those from the charcoal-block method for the pMDI with fast inhalation. The regional distribution of drug within the lungs and deposition in the oropharynx could be assessed by gamma scintigraphy, but not by the charcoal-block method. It is concluded that either method may be used to assess whole lung deposition of terbutaline sulphate from pMDIs, both with and without a spacer, although each method has its own inherent advantages and disadvantages. PMID:7784338

  17. Delivering a “Dose of Hope”: A Faith-Based Program to Increase Older African Americans’ Participation in Clinical Trials

    PubMed Central

    Omer, Saad B; Parker, Kimberly; Bolton, Marcus; Schamel, Jay; Shapiro, Eve; Owens, Lauren; Saint-Victor, Diane; Boggavarapu, Sahithi; Braxton, Nikia; Archibald, Matthew; Kalokhe, Ameeta S; Horton, Takeia; Root, Christin M; Fenimore, Vincent L; Anderson, Aaron M

    2015-01-01

    Background Underrepresentation of older-age racial and ethnic minorities in clinical research is a significant barrier to health in the United States, as it impedes medical research advancement of effective preventive and therapeutic strategies. Objective The objective of the study was to develop and test the feasibility of a community-developed faith-based intervention and evaluate its potential to increase the number of older African Americans in clinical research. Methods Using a cluster-randomized design, we worked with six matched churches to enroll at least 210 persons. We provided those in the intervention group churches with three educational sessions on the role of clinical trials in addressing health disparity topics, and those in the comparison group completed surveys at the same timepoints. All persons enrolled in the study received ongoing information via newsletters and direct outreach on an array of clinical studies seeking participants. We evaluated the short-, mid-, and longer-term effects of the interventional program on clinical trial-related outcomes (ie, screening and enrollment). Results From 2012 to 2013, we enrolled a balanced cohort of 221 persons in the program. At a 3-month follow-up, mean intention to seek information about clinical trials was higher than baseline in both treatment (mu=7.5/10; sigma=3.1) and control arms (mu=6.6/10; sigma=3.3), with the difference more pronounced in the treatment arm. The program demonstrated strong retention at 3-month (95.4%, 211/221) and 6-month timepoints (94.1%, 208/221). Conclusions The “Dose of Hope” program addressed an unmet need to reach an often overlooked audience of older African Americans who are members of churches and stimulate their interest in clinical trial participation. The program demonstrated its appeal in the delivery of effective messages and information about health disparities, and the role of clinical research in addressing these challenges. PMID:26036841

  18. Safety and Efficacy of High Dose AAV9 Encoding SERCA2a Delivered by Molecular Cardiac Surgery with Recirculating Delivery (MCARD) in Ovine Ischemic Cardiomyopathy

    PubMed Central

    Katz, Michael G.; Fargnoli, Anthony S.; Williams, Richard D.; Steuerwald, Nury M.; Isidro, Alice; Ivanina, Anna V.; Sokolova, Inna M.; Bridges, Charles R.

    2014-01-01

    Objective Therapeutic safety and efficacy are the basic prerequisites for clinical gene therapy. Herein we investigate the effect of high dose MCARD-mediated AAV9/SERCA2a gene delivery on clinical parameters, oxidative stress, humoral and cellular immune response, and cardiac remodeling. Methods Ischemic cardiomyopathy was generated in a sheep model. Then animals were assigned to one of two groups: control (n=10), and study (MCARD, n=6). The control had no intervention while the study group received 1014 gc of AAV9.SERCA2a 4 weeks post-infarction. Results Our ischemic model produced reliable infarcts leading to heart failure. The baseline ejection fraction (EF) in the MCARD group was 57.6±1.6 vs. 61.2±1.9 in the control group, (p>0.05). Twelve weeks post-infarction, the MCARD group had superior LV function compared to control: stroke volume index (46.6±1.8 vs. 35.8±2.5 mL/m2, p<0.05), EF (46.2±1.9 vs. 38.7±2.5%, p<0.05); and LV end systolic and end diastolic dimensions [41.3±1.7 vs. 48.2±1.4 mm; 51.2±1.5 vs. 57.6±1.7 mm], p<0.05. Markers of oxidative stress were significantly reduced in the infarct zone in the MCARD group. There was no positive T cell mediated immune response in the MCARD group at any time point. Myocyte hypertrophy was also significantly attenuated in the MCARD group compared to control. Conclusions Cardiac overexpression of the SERCA2a gene via MCARD is a safe therapeutic intervention. It significantly improves LV function, decreases markers of oxidative stress, abrogates myocyte hypertrophy, arrests remodeling and does not induce a T cell mediated immune response. PMID:25037619

  19. USE OF PBPK MODELS FOR ASSESSING ABSORBED DOSE AND CHE INHIBITION FROM AGGREGATE EXPOSURE OF INFANTS AND CHILDREN TO ORGANOPHOSPHORUS INSECTICIDES

    EPA Science Inventory

    A physiological pharmacokinetic (PBPK) modeling framework has been established to assess cumulative risk of dose and injury of infants and children to organophosphorus (OP) insecticides from aggregate sources and routes. Exposure inputs were drawn from all reasonable sources, pr...

  20. Estimation of absorbed dose in irradiated dates ( Phoenix dactylifera L.). Test of ESR response function by a weighted linear least-squares regression analysis

    NASA Astrophysics Data System (ADS)

    Ghelawi, M. A.; Moore, J. S.; Bisby, R. H.; Dodd, N. J. F.

    2001-01-01

    Food spoilage is caused by infestation by insects, contamination by bacteria and fungi and by deterioration by enzymes. In the third world, it has been estimated that 25% of agricultural products are lost before they reach the market. One way to decrease such losses is by treatment with ionising radiation and maximum permitted doses have been established for treatment of a wide variety of foods. For dates this dose is 2.0 kGy. Detection of irradiated foods is now essential and here we have used ESR to detect and estimate the dose received by a single date. The ESR spectrum of unirradiated date stone contains a single line g=2.0045 (signal A). Irradiation up to 2.0 kGy induces radical formation with g=1.9895, g=2.0159 (signal C) and g=1.9984 (signal B) high field. The lines with g=1.9895 and 2.0159 are readily detected and stable at room temperature for at least 27 months for samples irradiated up to this dose. The yield of the radicals resulting in these lines increase linearly up to a dose of 5.0 kGy as is evidenced by the linear increase in their intensity. In blind trials of 21 unirradiated and irradiated dates we are able to identify with 100% accuracy an irradiated sample and to estimate the dose to which the sample was irradiated to within ˜0.5 kGy.

  1. Integral dose: Comparison between four techniques for prostate radiotherapy

    PubMed Central

    Ślosarek, Krzysztof; Osewski, Wojciech; Grządziel, Aleksandra; Radwan, Michał; Dolla, Łukasz; Szlag, Marta; Stąpór-Fudzińska, Małgorzata

    2014-01-01

    Aim Comparisons of integral dose delivered to the treatment planning volume and to the whole patient body during stereotactic, helical and intensity modulated radiotherapy of prostate. Background Multifield techniques produce large volumes of low dose inside the patient body. Delivered dose could be the result of the cytotoxic injuries of the cells even away from the treatment field. We calculated the total dose absorbed in the patient body for four radiotherapy techniques to investigate whether some methods have a potential to reduce the exposure to the patient. Materials and methods We analyzed CyberKnife plans for 10 patients with localized prostate cancer. Five alternative plans for each patient were calculated with the VMAT, IMRT and TomoTherapy techniques. Alternative dose distributions were calculated to achieve the same coverage for PTV. Integral Dose formula was used to calculate the total dose delivered to the PTV and whole patient body. Results Analysis showed that the same amount of dose was deposited to the treated volume despite different methods of treatment delivery. The mean values of total dose delivered to the whole patient body differed significantly for each treatment technique. The highest integral dose in the patient's body was at the TomoTherapy and CyberKnife treatment session. VMAT was characterized by the lowest integral dose deposited in the patient body. Conclusions The highest total dose absorbed in normal tissue was observed with the use of a robotic radiosurgery system and TomoTherapy. These results demonstrate that the exposure of healthy tissue is a dosimetric factor which differentiates the dose delivery methods. PMID:25859398

  2. Assessment of the accuracy of an MCNPX-based Monte Carlo simulation model for predicting three-dimensional absorbed dose distributions

    PubMed Central

    Titt, U; Sahoo, N; Ding, X; Zheng, Y; Newhauser, W D; Zhu, X R; Polf, J C; Gillin, M T; Mohan, R

    2014-01-01

    In recent years, the Monte Carlo method has been used in a large number of research studies in radiation therapy. For applications such as treatment planning, it is essential to validate the dosimetric accuracy of the Monte Carlo simulations in heterogeneous media. The AAPM Report no 105 addresses issues concerning clinical implementation of Monte Carlo based treatment planning for photon and electron beams, however for proton-therapy planning, such guidance is not yet available. Here we present the results of our validation of the Monte Carlo model of the double scattering system used at our Proton Therapy Center in Houston. In this study, we compared Monte Carlo simulated depth doses and lateral profiles to measured data for a magnitude of beam parameters. We varied simulated proton energies and widths of the spread-out Bragg peaks, and compared them to measurements obtained during the commissioning phase of the Proton Therapy Center in Houston. Of 191 simulated data sets, 189 agreed with measured data sets to within 3% of the maximum dose difference and within 3 mm of the maximum range or penumbra size difference. The two simulated data sets that did not agree with the measured data sets were in the distal falloff of the measured dose distribution, where large dose gradients potentially produce large differences on the basis of minute changes in the beam steering. Hence, the Monte Carlo models of medium- and large-size double scattering proton-therapy nozzles were valid for proton beams in the 100 MeV–250 MeV interval. PMID:18670050

  3. WE-A-17A-01: Absorbed Dose Rate-To-Water at the Surface of a Beta-Emitting Planar Ophthalmic Applicator with a Planar, Windowless Extrapolation Chamber

    SciTech Connect

    Riley, A; Soares, C; Micka, J; Culberson, W; DeWerd, L

    2014-06-15

    Purpose: Currently there is no primary calibration standard for determining the absorbed dose rate-to-water at the surface of β-emitting concave ophthalmic applicators and plaques. Machining tolerances involved in the design of concave window extrapolation chambers are a limiting factor for development of such a standard. Use of a windowless extrapolation chamber avoids these window-machining tolerance issues. As a windowless extrapolation chamber has never been attempted, this work focuses on proof of principle measurements with a planar, windowless extrapolation chamber to verify the accuracy in comparison to initial calibration, which could be extended to the design of a hemispherical, windowless extrapolation chamber. Methods: The window of an extrapolation chamber defines the electrical field, aids in aligning the source parallel to the collector-guard assembly, and decreases the backscatter due to attenuation of lower electron energy. To create a uniform and parallel electric field in this research, the source was made common to the collector-guard assembly. A precise positioning protocol was designed to enhance the parallelism of the source and collector-guard assembly. Additionally, MCNP5 was used to determine a backscatter correction factor to apply to the calibration. With these issues addressed, the absorbed dose rate-to-water of a Tracerlab 90Sr planar ophthalmic applicator was determined using National Institute of Standards and Technology's (NIST) calibration formalism, and the results of five trials with this source were compared to measurements at NIST with a traditional extrapolation chamber. Results: The absorbed dose rate-to-water of the planar applicator was determined to be 0.473 Gy/s ±0.6%. Comparing these results to NIST's determination of 0.474 Gy/s yields a −0.6% difference. Conclusion: The feasibility of a planar, windowless extrapolation chamber has been demonstrated. A similar principle will be applied to developing a primary

  4. Use of Monte Carlo simulations with a realistic rat phantom for examining the correlation between hematopoietic system response and red marrow absorbed dose in Brown Norway rats undergoing radionuclide therapy with {sup 177}Lu- and {sup 90}Y-BR96 mAbs

    SciTech Connect

    Larsson, Erik; Ljungberg, Michael; Martensson, Linda; Nilsson, Rune; Tennvall, Jan; Strand, Sven-Erik; Joensson, Bo-Anders

    2012-07-15

    Purpose: Biokinetic and dosimetry studies in laboratory animals often precede clinical radionuclide therapies in humans. A reliable evaluation of therapeutic efficacy is essential and should be based on accurate dosimetry data from a realistic dosimetry model. The aim of this study was to develop an anatomically realistic dosimetry model for Brown Norway rats to calculate S factors for use in evaluating correlations between absorbed dose and biological effects in a preclinical therapy study. Methods: A realistic rat phantom (Roby) was used, which has some flexibility that allows for a redefinition of organ sizes. The phantom was modified to represent the anatomic geometry of a Brown Norway rat, which was used for Monte Carlo calculations of S factors. Kinetic data for radiolabeled BR96 monoclonal antibodies were used to calculate the absorbed dose. Biological data were gathered from an activity escalation study with {sup 90}Y- and {sup 177}Lu-labeled BR96 monoclonal antibodies, in which blood cell counts and bodyweight were examined up to 2 months follow-up after injection. Reductions in white blood cell and platelet counts and declines in bodyweight were quantified by four methods and compared to the calculated absorbed dose to the bone marrow or the total body. Results: A red marrow absorbed dose-dependent effect on hematological parameters was observed, which could be evaluated by a decrease in blood cell counts. The absorbed dose to the bone marrow, corresponding to the maximal tolerable activity that could safely be administered, was determined to 8.3 Gy for {sup 177}Lu and 12.5 Gy for {sup 90}Y. Conclusions: There was a clear correlation between the hematological effects, quantified with some of the studied parameters, and the calculated red marrow absorbed doses. The decline in body weight was stronger correlated to the total body absorbed dose, rather than the red marrow absorbed dose. Finally, when considering a constant activity concentration, the phantom

  5. Monte Carlo Simulations on Neutron Transport and Absorbed Dose in Tissue-Equivalent Phantoms Exposed to High-Flux Epithermal Neutron Beams

    NASA Astrophysics Data System (ADS)

    Bartesaghi, G.; Gambarini, G.; Negri, A.; Carrara, M.; Burian, J.; Viererbl, L.

    2010-04-01

    Presently there are no standard protocols for dosimetry in neutron beams for boron neutron capture therapy (BNCT) treatments. Because of the high radiation intensity and of the presence at the same time of radiation components having different linear energy transfer and therefore different biological weighting factors, treatment planning in epithermal neutron fields for BNCT is usually performed by means of Monte Carlo calculations; experimental measurements are required in order to characterize the neutron source and to validate the treatment planning. In this work Monte Carlo simulations in two kinds of tissue-equivalent phantoms are described. The neutron transport has been studied, together with the distribution of the boron dose; simulation results are compared with data taken with Fricke gel dosimeters in form of layers, showing a good agreement.

  6. [Evaluation of the dose equivalent absorbed by the population of Como and surrounding area following the nuclear reactor accident at Chernobyl].

    PubMed

    Cirla, A; Ostinelli, A; Zingales, A

    1987-12-01

    The effects produced as a consequence of the Chernobyl nuclear reactor accident in the population of Como are assessed on the basis of the measurements taken in the environment and on the food. Exposure measurements produced by external radiation and the activities of the different radionuclides introduced into the body, by ingestion and inhalation, made it possible to obtain an estimate of the dose equivalent and its somatic and genetic effects on the population. The results show that such effects may produce 0.5-2 cases of malignant tumour in the next 25 years and 0.2-1 case of genetic damage in the next 60 years and are therefore statistically insignificant.

  7. A method for a short-term forecast of the absorbed dose accumulation dynamics on the international space station based on radiation monitoring system data

    NASA Astrophysics Data System (ADS)

    Lishnevskii, A. E.; Benghin, V. V.

    2014-12-01

    Many papers are devoted to the prediction of radiation conditions on board of a spacecraft (Pichkhadze et al., 2004; Khamidullina et al., 2008; 2012), and a number of software systems for corresponding calculations have been developed: the US information system CREME96 (https://creme.isde.vander-bilt.edu/); European SPENVIS (http://www.spenvis.oma.be/intro.php); Russian SEREIS (Kuznetsov et al., 2001; Model' kosmosa, 2007) and COSRAD (http://cosrad.sinp.msu.ru/manual.html; Kuznetsov et al., 2011) based on the models of the radiation environment in near-Earth space (Bashkirov et al., 1998; Nymmik, 2004; Model' kosmosa, 2007; Kuznetsov et al., 2011). In this paper we propose a simple calculation algorithm of short-term (for a few days) forecasting of dynamics of the radiation dose on the International Space Station (ISS) in radiation environment undisturbed by solar proton events. This algorithm does not use radiation environment models and detailed ballistic calculations, while it uses data of the onboard radiation monitoring system (RMS) and empirical relations, obtained for ISS orbital motion.

  8. Advantage and limitations of weighting factors and weighted dose quantities and their units in boron neutron capture therapy.

    PubMed

    Rassow, J; Sauerwein, W; Wittig, A; Bourhis-Martin, E; Hideghéty, K; Moss, R

    2004-05-01

    Defining the parameters influencing the biological reaction due to absorbed dose is a continuous topic of research. The main goal of radiobiological research is to translate the measurable dose of ionizing radiation to a quantitative expression of biological effect. Mathematical models based on different biological approaches (e.g., skin reaction, cell culture) provide some estimations that are often misleading and, to some extent, dangerous. Conventional radiotherapy is the simplest case because the primary radiation and secondary radiation are both low linear energy transfer (LET) radiation and have about the same relative biological effectiveness (RBE). Nevertheless, for this one-dose-component case, the dose-effect curves are not linear. In fact, the total absorbed dose and the absorbed dose per fraction as well as the time schedule of the fractionation scheme influence the biological effects. Mathematical models such as the linear-quadratic model can only approximate biological effects. With regard to biological effects, fast neutron therapy is more complex than conventional radiotherapy. Fast neutron beams are always contaminated by gamma rays. As a consequence, biological effects are due to two components, a high-LET component (neutrons) and a low-LET component (photons). A straight transfer of knowledge from conventional radiotherapy to fast neutron therapy is, therefore, not possible: RBE depends on the delivered dose and several other parameters. For dose reporting, the European protocol for fast neutron dosimetry recommends that the total absorbed dose with gamma-ray absorbed dose in brackets is stated. However, boron neutron capture therapy (BNCT) is an even more complex case, because the total absorbed dose is due to four dose components with different LET and RBE. In addition, the terminology and units used by the different BNCT groups is confusing: absorbed dose and weighted dose are both to be stated in grays and are never "photon equivalent." The

  9. Factors for converting dose measured in polystyrene phantoms to dose reported in water phantoms for incident proton beams

    SciTech Connect

    Moyers, M. F.; Vatnitsky, A. S.; Vatnitsky, S. M.

    2011-10-15

    Purpose: Previous dosimetry protocols allowed calibrations of proton beamline dose monitors to be performed in plastic phantoms. Nevertheless, dose determinations were referenced to absorbed dose-to-muscle or absorbed dose-to-water. The IAEA Code of Practice TRS 398 recommended that dose calibrations be performed with ionization chambers only in water phantoms because plastic-to-water dose conversion factors were not available with sufficient accuracy at the time of its writing. These factors are necessary, however, to evaluate the difference in doses delivered to patients if switching from calibration in plastic to a protocol that only allows calibration in water. Methods: This work measured polystyrene-to-water dose conversion factors for this purpose. Uncertainties in the results due to temperature, geometry, and chamber effects were minimized by using special experimental set-up procedures. The measurements were validated by Monte Carlo simulations. Results: At the peak of non-range-modulated beams, measured polystyrene-to-water factors ranged from 1.015 to 1.024 for beams with ranges from 36 to 315 mm. For beams with the same ranges and medium sized modulations, the factors ranged from 1.005 to 1.019. The measured results were used to generate tables of polystyrene-to-water dose conversion factors. Conclusions: The dose conversion factors can be used at clinical proton facilities to support beamline and patient specific dose per monitor unit calibrations performed in polystyrene phantoms.

  10. Deformable Dose Reconstruction to Optimize the Planning and Delivery of Liver Cancer Radiotherapy

    NASA Astrophysics Data System (ADS)

    Velec, Michael

    The precise delivery of radiation to liver cancer patients results in improved control with higher tumor doses and minimized normal tissues doses. A margin of normal tissue around the tumor requires irradiation however to account for treatment delivery uncertainties. Daily image-guidance allows targeting of the liver, a surrogate for the tumor, to reduce geometric errors. However poor direct tumor visualization, anatomical deformation and breathing motion introduce uncertainties between the planned dose, calculated on a single pre-treatment computed tomography image, and the dose that is delivered. A novel deformable image registration algorithm based on tissue biomechanics was applied to previous liver cancer patients to track targets and surrounding organs during radiotherapy. Modeling these daily anatomic variations permitted dose accumulation, thereby improving calculations of the delivered doses. The accuracy of the algorithm to track dose was validated using imaging from a deformable, 3-dimensional dosimeter able to optically track absorbed dose. Reconstructing the delivered dose revealed that 70% of patients had substantial deviations from the initial planned dose. An alternative image-guidance technique using respiratory-correlated imaging was simulated, which reduced both the residual tumor targeting errors and the magnitude of the delivered dose deviations. A planning and delivery strategy for liver radiotherapy was then developed that minimizes the impact of breathing motion, and applied a margin to account for the impact of liver deformation during treatment. This margin is 38% smaller on average than the margin used clinically, and permitted an average dose-escalation to liver tumors of 9% for the same risk of toxicity. Simulating the delivered dose with deformable dose reconstruction demonstrated the plans with smaller margins were robust as 90% of patients' tumors received the intended dose. This strategy can be readily implemented with widely

  11. Key comparison BIPM.RI(I)-K6 of the standards for absorbed dose to water at 10 g cm-2 of the NMIJ, Japan and the BIPM in accelerator photon beams

    NASA Astrophysics Data System (ADS)

    Picard, S.; Burns, D. T.; Roger, P.; Shimizu, M.; Morishita, Y.; Kato, M.; Tanaka, T.; Kurosawa, T.; Saito, N.

    2016-01-01

    A comparison of the dosimetry for accelerator photon beams was carried out between the National Metrology Institute of Japan (NMIJ) and the Bureau International des Poids et Mesures (BIPM) from 9 to 23 April 2015. The comparison was based on the determination of absorbed dose to water at 10 g cm-2 for three radiation qualities at the NMIJ. The results, reported as ratios of the NMIJ and the BIPM evaluations (and with the combined standard uncertainties given in parentheses), are 0.9966 (47) at 6 MV, 0.9965 (60) at 10 MV and 0.9953 (50) at 15 MV. This result is the eighth in the on-going BIPM.RI(I)-K6 series of comparisons. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  12. Metallochaperones: bind and deliver

    SciTech Connect

    Rosenzweig, A.C.

    2010-03-08

    Metallochaperones deliver metal ions directly to target proteins via specific protein-protein interactions. Recent research has led to a molecular picture of how some metallochaperones bind metal ions, recognize their partner proteins, and accomplish metal ion transfer.

  13. Ir-192 HDR transit dose and radial dose function determination using alanine/EPR dosimetry

    NASA Astrophysics Data System (ADS)

    Guzmán Calcina, Carmen S.; de Almeida, Adelaide; Oliveira Rocha, José R.; Abrego, Felipe Chen; Baffa, Oswaldo

    2005-03-01

    Source positioning close to the tumour in high dose rate (HDR) brachytherapy is not instantaneous. An increment of dose will be delivered during the movement of the source in the trajectory to its static position. This increment is the transit dose, often not taken into account in brachytherapeutic treatment planning. The transit dose depends on the prescribed dose, number of treatment fractions, velocity and activity of the source. Combining all these factors, the transit dose can be 5% higher than the prescribed absorbed dose value (Sang-Hyun and Muller-Runkel, 1994 Phys. Med. Biol. 39 1181 8, Nath et al 1995 Med. Phys. 22 209 34). However, it cannot exceed this percentage (Nath et al 1995). In this work, we use the alanine-EPR (electron paramagnetic resonance) dosimetric system using analysis of the first derivative of the signal. The transit dose was evaluated for an HDR system and is consistent with that already presented for TLD dosimeters (Bastin et al 1993 Int. J. Radiat. Oncol. Biol. Phys. 26 695 702). Also using the same dosimetric system, the radial dose function, used to evaluate the geometric dose degradation around the source, was determined and its behaviour agrees better with those obtained by Monte Carlo simulations (Nath et al 1995, Williamson and Nath 1991 Med. Phys. 18 434 48, Ballester et al 1997 Med. Phys. 24 1221 8, Ballester et al 2001 Phys. Med. Biol. 46 N79 90) than with TLD measurements (Nath et al 1990 Med. Phys. 17 1032 40).

  14. Dosimetry and pharmacokinetics of monoclonal antibody A6H with human renal cell carcinoma xenografts: single dose study.

    PubMed

    Palme, D F; Berkopec, J M; Wessels, B W; Elson, M K; Lange, P H; Vessella, R L

    1991-01-01

    Implantable miniature thermoluminescent dosimeters and conventional biodistribution analysis were used to determine the locally absorbed radiation dose delivered to three morphologically distinct human renal cell carcinoma xenografts (TK-39, TK-82 and TK-177C; N = 87) following a 50 microCi infusion of 131iodine-labeled monoclonal antibody A6H. Xenografts were clearly detected by radioimmuno-scintigraphy. Pronounced differences were noted among the three xenografts in MAb pharmacokinetics and in the locally absorbed irradiation doses which ranged from 2 to 5 cGy per injected microCi of 131iodine-labelled A6H. PMID:1917523

  15. Can solar power deliver?

    PubMed

    Nelson, Jenny; Emmott, Christopher J M

    2013-08-13

    Solar power represents a vast resource which could, in principle, meet the world's needs for clean power generation. Recent growth in the use of photovoltaic (PV) technology has demonstrated the potential of solar power to deliver on a large scale. Whilst the dominant PV technology is based on crystalline silicon, a wide variety of alternative PV materials and device concepts have been explored in an attempt to decrease the cost of the photovoltaic electricity. This article explores the potential for such emerging technologies to deliver cost reductions, scalability of manufacture, rapid carbon mitigation and new science in order to accelerate the uptake of solar power technologies.

  16. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  17. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  18. Modelling Absorbent Phenomena of Absorbent Structure

    NASA Astrophysics Data System (ADS)

    Sayeb, S.; Ladhari, N.; Ben Hassen, M.; Sakli, F.

    Absorption, retention and strike through time, as evaluating criteria of absorbent structures quality were studied. Determination of influent parameters on these criteria were realized by using the design method of experimental sets. In this study, the studied parameters are: Super absorbent polymer (SAP)/fluff ratio, compression and the porosity of the non woven used as a cover stock. Absorption capacity and retention are mostly influenced by SAP/fluff ratio. However, strike through time is affected by compression. Thus, a modelling of these characteristics in function of the important parameter was established.

  19. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  20. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  1. Defining the “Hostile Pelvis” for Intensity Modulated Radiation Therapy: The Impact of Anatomic Variations in Pelvic Dimensions on Dose Delivered to Target Volumes and Organs at Risk in Patients With High-Risk Prostate Cancer Treated With Whole Pelvic Radiation Therapy

    SciTech Connect

    Yirmibeşoğlu Erkal, Eda; Karabey, Sinan; Karabey, Ayşegül; Hayran, Mutlu; Erkal, Haldun Şükrü

    2015-07-15

    Purpose: The aim of this study was to evaluate the impact of variations in pelvic dimensions on the dose delivered to the target volumes and the organs at risk (OARs) in patients with high-risk prostate cancer (PCa) to be treated with whole pelvic radiation therapy (WPRT) in an attempt to define the hostile pelvis in terms of intensity modulated radiation therapy (IMRT). Methods and Materials: In 45 men with high-risk PCa to be treated with WPRT, the target volumes and the OARs were delineated, the dose constraints for the OARs were defined, and treatment plans were generated according to the Radiation Therapy Oncology Group 0924 protocol. Six dimensions to reflect the depth, width, and height of the bony pelvis were measured, and 2 indexes were calculated from the planning computed tomographic scans. The minimum dose (D{sub min}), maximum dose (D{sub max}), and mean dose (D{sub mean}) for the target volumes and OARs and the partial volumes of each of these structures receiving a specified dose (V{sub D}) were calculated from the dose-volume histograms (DVHs). The data from the DVHs were correlated with the pelvic dimensions and indexes. Results: According to an overall hostility score (OHS) calculation, 25 patients were grouped as having a hospitable pelvis and 20 as having a hostile pelvis. Regarding the OHS grouping, the DVHs for the bladder, bowel bag, left femoral head, and right femoral head differed in favor of the hospitable pelvis group, and the DVHs for the rectum differed for a range of lower doses in favor of the hospitable pelvis group. Conclusions: Pelvimetry might be used as a guide to define the challenging anatomy or the hostile pelvis in terms of treatment planning for IMRT in patients with high-risk PCa to be treated with WPRT.

  2. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  3. Absorbing Outflows in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  4. Effects of internal low-dose irradiation from 131I on gene expression in normal tissues in Balb/c mice

    PubMed Central

    2011-01-01

    Background The aim of this study was to investigate the global gene expression response of normal tissues following internal low absorbed dose irradiation of 131I. Methods Balb/c mice were intravenously injected with 13 to 260 kBq of 131I and euthanized 24 h after injection. Kidneys, liver, lungs, and spleen were surgically removed. The absorbed dose to the tissues was 0.1 to 9.7 mGy. Total RNA was extracted, and Illumina MouseRef-8 Whole-Genome Expression BeadChips (Illumina, Inc., San Diego, California, USA) were used to compare the gene expression of the irradiated tissues to that of non-irradiated controls. The Benjamini-Hochberg method was used to determine differentially expressed transcripts and control for false discovery rate. Only transcripts with a modulation of 1.5-fold or higher, either positively or negatively regulated, were included in the analysis. Results The number of transcripts affected ranged from 260 in the kidney cortex to 857 in the lungs. The majority of the affected transcripts were specific for the different absorbed doses delivered, and few transcripts were shared between the different tissues investigated. The response of the transcripts affected at all dose levels was generally found to be independent of dose, and only a few transcripts showed increasing or decreasing regulation with increasing absorbed dose. Few biological processes were affected at all absorbed dose levels studied or in all tissues studied. The types of biological processes affected were clearly tissue-dependent. Immune response was the only biological process affected in all tissues, and processes affected in more than three tissues were primarily associated with the response to stimuli and metabolism. Conclusion Despite the low absorbed doses delivered to the tissues investigated, a surprisingly strong response was observed. Affected biological processes were primarily associated with the normal function of the tissues, and only small deviations from the normal

  5. Computational assessment of effective dose and patient specific doses for kilovoltage stereotactic radiosurgery of wet age-related macular degeneration

    NASA Astrophysics Data System (ADS)

    Hanlon, Justin Mitchell

    Age-related macular degeneration (AMD) is a leading cause of vision loss and a major health problem for people over the age of 50 in industrialized nations. The current standard of care, ranibizumab, is used to help slow and in some cases stabilize the process of AMD, but requires frequent invasive injections into the eye. Interest continues for stereotactic radiosurgery (SRS), an option that provides a non-invasive treatment for the wet form of AMD, through the development of the IRay(TM) (Oraya Therapeutics, Inc., Newark, CA). The goal of this modality is to destroy choroidal neovascularization beneath the pigment epithelium via delivery of three 100 kVp photon beams entering through the sclera and overlapping on the macula delivering up to 24 Gy of therapeutic dose over a span of approximately 5 minutes. The divergent x-ray beams targeting the fovea are robotically positioned and the eye is gently immobilized by a suction-enabled contact lens. Device development requires assessment of patient effective dose, reference patient mean absorbed doses to radiosensitive tissues, and patient specific doses to the lens and optic nerve. A series of head phantoms, including both reference and patient specific, was derived from CT data and employed in conjunction with the MCNPX 2.5.0 radiation transport code to simulate treatment and evaluate absorbed doses to potential tissues-at-risk. The reference phantoms were used to evaluate effective dose and mean absorbed doses to several radiosensitive tissues. The optic nerve was modeled with changeable positions based on individual patient variability seen in a review of head CT scans gathered. Patient specific phantoms were used to determine the effect of varying anatomy and gaze. The results showed that absorbed doses to the non-targeted tissues were below the threshold levels for serious complications; specifically the development of radiogenic cataracts and radiation induced optic neuropathy (RON). The effective dose

  6. Internal absorber solar collector

    DOEpatents

    Sletten, Carlyle J.; Herskovitz, Sheldon B.; Holt, F. S.; Sletten, E. J.

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector. The miniature internal absorbers are generally made of solid copper with black selective surface and the collected solar heat is extracted at the collector ends by thermal conductivity along the absorber rods. Heat is removed from end fittings by use of liquid circulants. Several alternate constructions are provided for simplifying collector panel fabrication and for preventing the thermal expansion and contraction of the heated absorber or circulant tubes from damaging vacuum seals. In a modified version of the internal absorber collector, oil with temperature dependent viscosity is pumped through a segmented absorber which is now composed of closely spaced insulated metal tubes. In this way the circulant is automatically diverted through heated portions of the absorber giving higher collector concentration ratios than theoretically possible for an unsegmented absorber.

  7. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  8. Comparison of Radiation Dose Estimation for Myeloablative Radioimmunotherapy for Relapsed or Recurrent Mantle Cell Lymphoma using 131I Tositumomab to that of Other Types of Non-Hodgkin's Lymphoma

    SciTech Connect

    Rajendran, Joseph G.; Gopal, Ajay K.; Durack, Larry; Fisher, Darrell R.; Press, Oliver W.; Eary, Janet F.

    2004-12-01

    Patients with relapsed or refractory mantle cell lymphoma (MCL) demonstrate poor survival after standard treatment. Myeloablative radioimmunotherapy (RIT) using 131I tositumomab (anti-CD20) has the ability to deliver specific radiation absorbed dose to antigen bearing tumor. We reviewed normal organ radiation absorbed doses in MCL patients. METHODS: Records of patients with MCL (n = 25), who received myeloablative RIT between January 1996 and December 2003 were reviewed. Individual patient radiation dosimetry was performed on all patients after a trace labeled infusion of 131I tositumomab (mean = 348 MBq), to calculate the required amount of radioactivity for therapy, based on MIRD schema. RESULTS: Mean organ residence times (hr) corrected for CT derived organ volumes for MCL, were as follows: Lungs:9.0; Liver:12.4; Kidneys:1.7; Spleen:2.17; Whole Body:62.4 and mean radiation absorbed doses mGy/Mbq were: Lungs:1.2; Liver:1.1; Kidneys:0.85; Spleen:1.7; Whole Body: 0.21. This is similar to patients with other NHL. Patients received a mean activity of 21 GBq of 131I (range = 11.5 - 41.4) for therapy estimated to deliver 25 Gy to the normal organ receiving the highest radiation absorbed dose. CONCLUSION: Myeloablative RIT using 131I tositumomab results in normal organ radiation absorbed doses similar to those in patients with other non-Hodgkin's lymphoma, and is suitable for treating patients with relapsed or refractory MCL.

  9. Diagnostic beam absorber in Mu2e beam line

    SciTech Connect

    Rakhno, Igor; /Fermilab

    2011-03-01

    Star density, hadron flux, and residual dose distributions are calculated around the {mu}2e diagnostic beam absorber. Corresponding surface and ground water activation, and air activation are presented as well.

  10. Unidirectional perfect absorber

    PubMed Central

    Jin, L.; Wang, P.; Song, Z.

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  11. Unidirectional perfect absorber

    NASA Astrophysics Data System (ADS)

    Jin, L.; Wang, P.; Song, Z.

    2016-09-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  12. Unidirectional perfect absorber.

    PubMed

    Jin, L; Wang, P; Song, Z

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  13. Mechanical energy absorber

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J. (Inventor)

    1993-01-01

    An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

  14. Unidirectional perfect absorber.

    PubMed

    Jin, L; Wang, P; Song, Z

    2016-09-12

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  15. Dose quality assurance for industrial irradiation with an electron linac

    NASA Astrophysics Data System (ADS)

    White, B. F.; Lawrence, C. B.; Lee-Whiting, G. E.; Lord, S.; Mason, V. A.; Smyth, D. L.; Ungrin, J.

    1989-04-01

    In the development of the IMPELA family of electron linacs for industrial radiation processing, the needs for on-line monitoring of exposure dose have been recognized. The diverse applications under consideration demand a broad range of control-system performance and delivered-dose assurance measures appropriate to the sensitivities of the processes. The AAMI Guideline for Electron Beam Radiation Sterilization of Medical Devices points to a probable upper bound to the complexity of such requirements. ASTM and IAEA standards and guidelines for radiation dosimetry define the methods available for off-line verification of absorbed dose. The impact of the requirements for on-line measurements and the limitations inherent to the IMPELA design, are reviewed. The interdependencies of off-line product dosimetry and analyses with the on-line monitoring of process parameters are explored in search of criteria for optimization of cost-effective, flexible industrial irradiators.

  16. Dose rate effect on micronuclei induction in human blood lymphocytes exposed to single pulse and multiple pulses of electrons.

    PubMed

    Acharya, Santhosh; Bhat, N N; Joseph, Praveen; Sanjeev, Ganesh; Sreedevi, B; Narayana, Y

    2011-05-01

    The effects of single pulses and multiple pulses of 7 MV electrons on micronuclei (MN) induction in cytokinesis-blocked human peripheral blood lymphocytes (PBLs) were investigated over a wide range of dose rates per pulse (instantaneous dose rate). PBLs were exposed to graded doses of 2, 3, 4, 6, and 8 Gy of single electron pulses of varying pulse widths at different dose rates per pulse, ranging from 1 × 10(6) Gy s(-1) to 3.2 × 10(8) Gy s(-1). Different dose rates per pulse were achieved by changing the dose per electron pulse by adjusting the beam current and pulse width. MN yields per unit absorbed dose after irradiation with single electron pulses were compared with those of multiple pulses of electrons. A significant decrease in the MN yield with increasing dose rates per pulse was observed, when dose was delivered by a single electron pulse. However, no reduction in the MN yield was observed when dose was delivered by multiple pulses of electrons. The decrease in the yield at high dose rates per pulse suggests possible radical recombination, which leads to decreased biological damage. Cellular response to the presence of very large numbers of chromosomal breaks may also alter the damage.

  17. Delivering bad news to patients.

    PubMed

    Monden, Kimberley R; Gentry, Lonnie; Cox, Thomas R

    2016-01-01

    When physicians lack proper training, breaking bad news can lead to negative consequences for patients, families, and physicians. A questionnaire was used to determine whether a didactic program on delivering bad news was needed at our institution. Results revealed that 91% of respondents perceived delivering bad news as a very important skill, but only 40% felt they had the training to effectively deliver such news. We provide a brief review of different approaches to delivering bad news and advocate for training physicians in a comprehensive, structured model.

  18. Neutron Absorbing Alloys

    DOEpatents

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  19. Solar concentrator/absorber

    NASA Technical Reports Server (NTRS)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  20. Absorbing Software Testing into the Scrum Method

    NASA Astrophysics Data System (ADS)

    Tuomikoski, Janne; Tervonen, Ilkka

    In this paper we study, how to absorb software testing into the Scrum method. We conducted the research as an action research during the years 2007-2008 with three iterations. The result showed that testing can and even should be absorbed to the Scrum method. The testing team was merged into the Scrum teams. The teams can now deliver better working software in a shorter time, because testing keeps track of the progress of the development. Also the team spirit is higher, because the Scrum team members are committed to the same goal. The biggest change from test manager’s point of view was the organized Product Owner Team. Test manager don’t have testing team anymore, and in the future all the testing tasks have to be assigned through the Product Backlog.

  1. Fast motion-including dose error reconstruction for VMAT with and without MLC tracking.

    PubMed

    Ravkilde, Thomas; Keall, Paul J; Grau, Cai; Høyer, Morten; Poulsen, Per R

    2014-12-01

    Multileaf collimator (MLC) tracking is a promising and clinically emerging treatment modality for radiotherapy of mobile tumours. Still, new quality assurance (QA) methods are warranted to safely introduce MLC tracking in the clinic. The purpose of this study was to create and experimentally validate a simple model for fast motion-including dose error reconstruction applicable to intrafractional QA of MLC tracking treatments of moving targets.MLC tracking experiments were performed on a standard linear accelerator with prototype MLC tracking software guided by an electromagnetic transponder system. A three-axis motion stage reproduced eight representative tumour trajectories; four lung and four prostate. Low and high modulation 6 MV single-arc volumetric modulated arc therapy treatment plans were delivered for each trajectory with and without MLC tracking, as well as without motion for reference. Temporally resolved doses were measured during all treatments using a biplanar dosimeter. Offline, the dose delivered to each of 1069 diodes in the dosimeter was reconstructed with 500 ms temporal resolution by a motion-including pencil beam convolution algorithm developed in-house. The accuracy of the algorithm for reconstruction of dose and motion-induced dose errors throughout the tracking and non-tracking beam deliveries was quantified. Doses were reconstructed with a mean dose difference relative to the measurements of-0.5% (5.5% standard deviation) for cumulative dose. More importantly, the root-mean-square deviation between reconstructed and measured motion-induced 3%/3 mm γ failure rates (dose error) was 2.6%. The mean computation time for each calculation of dose and dose error was 295 ms. The motion-including dose reconstruction allows accurate temporal and spatial pinpointing of errors in absorbed dose and is adequately fast to be feasible for online use. An online implementation could allow treatment intervention in case of erroneous dose delivery in both

  2. Metasurface Broadband Solar Absorber

    PubMed Central

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  3. Metasurface Broadband Solar Absorber.

    PubMed

    Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  4. Metasurface Broadband Solar Absorber

    DOE PAGES

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

  5. Metasurface Broadband Solar Absorber.

    PubMed

    Azad, Abul K; Kort-Kamp, Wilton J M; Sykora, Milan; Weisse-Bernstein, Nina R; Luk, Ting S; Taylor, Antoinette J; Dalvit, Diego A R; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  6. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  7. Synchronized dynamic dose reconstruction

    SciTech Connect

    Litzenberg, Dale W.; Hadley, Scott W.; Tyagi, Neelam; Balter, James M.; Ten Haken, Randall K.; Chetty, Indrin J.

    2007-01-15

    Variations in target volume position between and during treatment fractions can lead to measurable differences in the dose distribution delivered to each patient. Current methods to estimate the ongoing cumulative delivered dose distribution make idealized assumptions about individual patient motion based on average motions observed in a population of patients. In the delivery of intensity modulated radiation therapy (IMRT) with a multi-leaf collimator (MLC), errors are introduced in both the implementation and delivery processes. In addition, target motion and MLC motion can lead to dosimetric errors from interplay effects. All of these effects may be of clinical importance. Here we present a method to compute delivered dose distributions for each treatment beam and fraction, which explicitly incorporates synchronized real-time patient motion data and real-time fluence and machine configuration data. This synchronized dynamic dose reconstruction method properly accounts for the two primary classes of errors that arise from delivering IMRT with an MLC: (a) Interplay errors between target volume motion and MLC motion, and (b) Implementation errors, such as dropped segments, dose over/under shoot, faulty leaf motors, tongue-and-groove effect, rounded leaf ends, and communications delays. These reconstructed dose fractions can then be combined to produce high-quality determinations of the dose distribution actually received to date, from which individualized adaptive treatment strategies can be determined.

  8. A Biodosimeter for Multiparametric Determination of Radiation Dose, Radiation Quality, and Radiation Risk

    NASA Technical Reports Server (NTRS)

    Richmond, Robert; Cruz, Angela; Jansen, Heather; Bors, Karen

    2003-01-01

    Predicting risk of human cancer following exposure of an individual or a population to ionizing radiation is challenging. To an approximation, this is because uncertainties of uniform absorption of dose and the uniform processing of dose-related damage at the cellular level within a complex set of biological variables degrade the confidence of predicting the delayed expression of cancer as a relatively rare event. Cellular biodosimeters that simultaneously report: 1) the quantity of absorbed dose after exposure to ionizing radiation, 2) the quality of radiation delivering that dose, and 3) the risk of developing cancer by the cells absorbing that dose would therefore be useful. An approach to such a multiparametric biodosimeter will be reported. This is the demonstration of a dose responsive field effect of enhanced expression of keratin 18 (K18) in cultures of human mammary epithelial cells irradiated with cesium-1 37 gamma-rays. Dose response of enhanced K18 expression was experimentally extended over a range of 30 to 90 cGy for cells evaluated at mid-log phase. K18 has been reported to be a marker for tumor staging and for apoptosis, and thereby serves as an example of a potential marker for cancer risk, where the reality of such predictive value would require additional experimental development. Since observed radiogenic increase in expression of K18 is a field effect, ie., chronically present in all cells of the irradiated population, it may be hypothesized that K18 expression in specific cells absorbing particulate irradiation, such as the high-LET-producing atomic nuclei of space radiation, will report on both the single-cell distributions of those particles amongst cells within the exposed population, and that the relatively high dose per cell delivered by densely ionizing tracks of those intersecting particles will lead to cell-specific high-expression levels of K18, thereby providing analytical end points that may be used to resolve both the quantity and

  9. Estimate Radiological Dose for Animals

    1997-12-18

    Estimate Radiological dose for animals in ecological environment using open literature values for parameters such as body weight, plant and soil ingestion rate, rad. halflife, absorbed energy, biological halflife, gamma energy per decay, soil-to-plant transfer factor, ...etc

  10. Know your dose: RADDOSE

    PubMed Central

    Paithankar, Karthik S.; Garman, Elspeth F.

    2010-01-01

    The program RADDOSE is widely used to compute the dose absorbed by a macromolecular crystal during an X-ray diffraction experiment. A number of factors affect the absorbed dose, including the incident X-ray flux density, the photon energy and the composition of the macromolecule and of the buffer in the crystal. An experimental dose limit for macromolecular crystallography (MX) of 30 MGy at 100 K has been reported, beyond which the biological information obtained may be compromised. Thus, for the planning of an optimized diffraction experiment the estimation of dose has become an additional tool. A number of approximations were made in the original version of RADDOSE. Recently, the code has been modified in order to take into account fluorescent X-­ray escape from the crystal (version 2) and the inclusion of incoherent (Compton) scattering into the dose calculation is now reported (version 3). The Compton cross-section, although negligible at the energies currently commonly used in MX, should be considered in dose calculations for incident energies above 20 keV. Calculations using version 3 of RADDOSE reinforce previous studies that predict a reduction in the absorbed dose when data are collected at higher energies compared with data collected at 12.4 keV. Hence, a longer irradiation lifetime for the sample can be achieved at these higher energies but this is at the cost of lower diffraction intensities. The parameter ‘diffraction-dose efficiency’, which is the diffracted intensity per absorbed dose, is revisited in an attempt to investigate the benefits and pitfalls of data collection using higher and lower energy radiation, particularly for thin crystals. PMID:20382991

  11. Absorber for terahertz radiation management

    DOEpatents

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  12. Dosimetric study of the effective doses resulting during dental X-ray and panoramic radiography

    NASA Astrophysics Data System (ADS)

    Shousha, Hany A.; Abd-El Hafez, A. I.; Ahmad, Fawzia

    2011-01-01

    The panoramic image is one of the most commonly used radiographic examinations in dentistry, owing to its low dose and large area for evaluation, including bone and teeth in the same image. Although digital images are usually reported to deliver a lower radiation dose to the patient, conventional images are still available, especially in countries where digital systems are not widely economically available. Dentists should weigh the benefits of dental radiographs against the consequences of increasing a patient's exposure to radiation, the effects of which accumulate from multiple sources over time. The "as low as reasonably achievable" principle should be followed to minimize the exposure to radiation. The purpose of this investigation is to measure the absorbed radiation doses at 12 anatomical sites of a Rando-phantom and calculate the effective doses result from a full-mouth survey and panoramic radiography. Organ-absorbed doses are measured using thermoluminescent dosimeters (TLD 100) and effective organ doses (μ Sv) are estimated according to the International Commission on Radiological Protection in 2007. The total effective dose results from the panoramic imaging system have so far been below those obtained using the full-mouth survey technique used in intra-oral radiographic examination.

  13. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  14. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C.; Lee, Chuck K.; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  15. Underwater acoustic omnidirectional absorber

    NASA Astrophysics Data System (ADS)

    Naify, Christina J.; Martin, Theodore P.; Layman, Christopher N.; Nicholas, Michael; Thangawng, Abel L.; Calvo, David C.; Orris, Gregory J.

    2014-02-01

    Gradient index media, which are designed by varying local element properties in given geometry, have been utilized to manipulate acoustic waves for a variety of devices. This study presents a cylindrical, two-dimensional acoustic "black hole" design that functions as an omnidirectional absorber for underwater applications. The design features a metamaterial shell that focuses acoustic energy into the shell's core. Multiple scattering theory was used to design layers of rubber cylinders with varying filling fractions to produce a linearly graded sound speed profile through the structure. Measured pressure intensity agreed with predicted results over a range of frequencies within the homogenization limit.

  16. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  17. Application of radiochromic gel detector (FXG) for UVA dose measurements

    NASA Astrophysics Data System (ADS)

    Abukassem, Issam; Bero, Mamdouh A.

    2010-12-01

    Tissue equivalent radiochromic gel material containing ferrous ions, xylenol-orange ion indicator and gelatin as gelling agent (FXG) is known to be sensitive to γ- and X-rays; hence it has been used for ionizing radiation dosimetry. Changes in optical absorbance properties of FXG material over a wide region in the visible spectrum were found to be proportional to the radiation absorbed dose. An earlier study demonstrated the sensitivity of FXG gel detector to ultraviolet radiation and therefore that could give quantitative measure for UV exposure. This study focuses on the detection of UVA radiation (315-400 nm), which forms an important part (˜97%) of the natural solar UV radiation reaching the earth surface. A solar UV simulator device was used to deliver UVA radiation to FXG samples. The beam was optically modified to irradiate gel samples at an exposure level about 58 W/m 2, which is comparable to the summer natural UVA radiation measured outside the laboratory building at midday (˜60 W/m 2). Experimental results were used to generate mathematical second order formulas that give the relationship between UVA dose and optical absorbance changes observed at two wavelengths in the visible region of the spectrum—430 and 560 nm.

  18. Liquid Cryogen Absorber for MICE

    SciTech Connect

    Baynham, D.E.; Bish, P.; Bradshaw, T.W.; Cummings, M.A.; Green,M.A.; Ishimoto, S.; Ivaniouchenkov, I.; Lau, W.; Yang, S.Q.; Zisman, M.S.

    2005-08-20

    The Muon Ionization Cooling Experiment (MICE) will test ionization cooling of muons. In order to have effective ionization cooling, one must use an absorber that is made from a low-z material. The most effective low z materials for ionization cooling are hydrogen, helium, lithium hydride, lithium and beryllium, in that order. In order to measure the effect of material on cooling, several absorber materials must be used. This report describes a liquid-hydrogen absorber that is within a pair of superconducting focusing solenoids. The absorber must also be suitable for use with liquid helium. The following absorber components are discussed in this report; the absorber body, its heat exchanger, the hydrogen system, and the hydrogen safety. Absorber cooling and the thin windows are not discussed here.

  19. A novel simple phantom for verifying the dose of radiation therapy.

    PubMed

    Lee, J H; Chang, L T; Shiau, A C; Chen, C W; Liao, Y J; Li, W J; Lee, M S; Hsu, S M

    2015-01-01

    A standard protocol of dosimetric measurements is used by the organizations responsible for verifying that the doses delivered in radiation-therapy institutions are within authorized limits. This study evaluated a self-designed simple auditing phantom for use in verifying the dose of radiation therapy; the phantom design, dose audit system, and clinical tests are described. Thermoluminescent dosimeters (TLDs) were used as postal dosimeters, and mailable phantoms were produced for use in postal audits. Correction factors are important for converting TLD readout values from phantoms into the absorbed dose in water. The phantom scatter correction factor was used to quantify the difference in the scattered dose between a solid water phantom and homemade phantoms; its value ranged from 1.084 to 1.031. The energy-dependence correction factor was used to compare the TLD readout of the unit dose irradiated by audit beam energies with (60)Co in the solid water phantom; its value was 0.99 to 1.01. The setup-condition factor was used to correct for differences in dose-output calibration conditions. Clinical tests of the device calibrating the dose output revealed that the dose deviation was within 3%. Therefore, our homemade phantoms and dosimetric system can be applied for accurately verifying the doses applied in radiation-therapy institutions.

  20. A Novel Simple Phantom for Verifying the Dose of Radiation Therapy

    PubMed Central

    Lee, J. H.; Chang, L. T.; Shiau, A. C.; Chen, C. W.; Liao, Y. J.; Li, W. J.; Lee, M. S.; Hsu, S. M.

    2015-01-01

    A standard protocol of dosimetric measurements is used by the organizations responsible for verifying that the doses delivered in radiation-therapy institutions are within authorized limits. This study evaluated a self-designed simple auditing phantom for use in verifying the dose of radiation therapy; the phantom design, dose audit system, and clinical tests are described. Thermoluminescent dosimeters (TLDs) were used as postal dosimeters, and mailable phantoms were produced for use in postal audits. Correction factors are important for converting TLD readout values from phantoms into the absorbed dose in water. The phantom scatter correction factor was used to quantify the difference in the scattered dose between a solid water phantom and homemade phantoms; its value ranged from 1.084 to 1.031. The energy-dependence correction factor was used to compare the TLD readout of the unit dose irradiated by audit beam energies with 60Co in the solid water phantom; its value was 0.99 to 1.01. The setup-condition factor was used to correct for differences in dose-output calibration conditions. Clinical tests of the device calibrating the dose output revealed that the dose deviation was within 3%. Therefore, our homemade phantoms and dosimetric system can be applied for accurately verifying the doses applied in radiation-therapy institutions. PMID:25883980

  1. Outdoor solar UVA dose assessment with EBT2 radiochromic film using spectrophotometer and densitometer measurements.

    PubMed

    Abukassem, I; Bero, M A

    2015-04-01

    Direct measurements of solar ultraviolet radiations (UVRs) have an important role in the protection of humans against UVR hazard. This work presents simple technique based on the application of EBT2 GAFCHROMIC(®) film for direct solar UVA dose assessment. It demonstrates the effects of different parts of the solar spectrum (UVB, visible and infrared) on performed UVA field measurements and presents the measurement uncertainty budget. The gradient of sunlight exposure level permitted the authors to establish the mathematical relationships between the measured solar UVA dose and two measured quantities: the first was the changes in spectral absorbance at the wavelength 633 nm (A633) and the second was the optical density (OD). The established standard relations were also applied to calculate the solar UVA dose variations during the whole day; 15 min of exposure each hour between 8:00 and 17:00 was recorded. Results show that both applied experimental methods, spectrophotometer absorbance and densitometer OD, deliver comparable figures for EBT2 solar UVA dose assessment with relative uncertainty of 11% for spectral absorbance measurements and 15% for OD measurements. PMID:25500756

  2. Dual broadband metamaterial absorber.

    PubMed

    Kim, Young Ju; Yoo, Young Joon; Kim, Ki Won; Rhee, Joo Yull; Kim, Yong Hwan; Lee, YoungPak

    2015-02-23

    We propose polarization-independent and dual-broadband metamaterial absorbers at microwave frequencies. This is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones. We demonstrate not only one broadband absorption from the fundamental magnetic resonances but additional broadband absorption in high-frequency range using the third-harmonic resonance, by both simulation and experiment. In simulation, the absorption was over 90% in 3.93-6.05 GHz, and 11.64-14.55 GHz. The corresponding experimental absorption bands over 90% were 3.88-6.08 GHz, 9.95-10.46 GHz and 11.86-13.84 GHz, respectively. The origin of absorption bands was elucidated. Furthermore, it is independent of polarization angle owing to the multilayered circular structures. The design is scalable to smaller size for the infrared and the visible ranges.

  3. Absorber coatings' degradation

    SciTech Connect

    Moore, S.W.

    1984-01-01

    This report is intended to document some of the Los Alamos efforts that have been carried out under the Department of Energy (DOE) Active Heating and Cooling Materials Reliability, Maintainability, and Exposure Testing program. Funding for these activities is obtained directly from DOE although they represent a variety of projects and coordination with other agencies. Major limitations to the use of solar energy are the uncertain reliability and lifetimes of solar systems. This program is aimed at determining material operating limitations, durabilities, and failure modes such that materials improvements can be made and lifetimes can be extended. Although many active and passive materials and systems are being studied at Los Alamos, this paper will concentrate on absorber coatings and degradation of these coatings.

  4. Use of effective dose.

    PubMed

    Harrison, J D; Balonov, M; Martin, C J; Ortiz Lopez, P; Menzel, H-G; Simmonds, J R; Smith-Bindman, R; Wakeford, R

    2016-06-01

    International Commission on Radiological Protection (ICRP) Publication 103 provided a detailed explanation of the purpose and use of effective dose and equivalent dose to individual organs and tissues. Effective dose has proven to be a valuable and robust quantity for use in the implementation of protection principles. However, questions have arisen regarding practical applications, and a Task Group has been set up to consider issues of concern. This paper focusses on two key proposals developed by the Task Group that are under consideration by ICRP: (1) confusion will be avoided if equivalent dose is no longer used as a protection quantity, but regarded as an intermediate step in the calculation of effective dose. It would be more appropriate for limits for the avoidance of deterministic effects to the hands and feet, lens of the eye, and skin, to be set in terms of the quantity, absorbed dose (Gy) rather than equivalent dose (Sv). (2) Effective dose is in widespread use in medical practice as a measure of risk, thereby going beyond its intended purpose. While doses incurred at low levels of exposure may be measured or assessed with reasonable reliability, health effects have not been demonstrated reliably at such levels but are inferred. However, bearing in mind the uncertainties associated with risk projection to low doses or low dose rates, it may be considered reasonable to use effective dose as a rough indicator of possible risk, with the additional consideration of variation in risk with age, sex and population group. PMID:26980800

  5. Use of effective dose.

    PubMed

    Harrison, J D; Balonov, M; Martin, C J; Ortiz Lopez, P; Menzel, H-G; Simmonds, J R; Smith-Bindman, R; Wakeford, R

    2016-06-01

    International Commission on Radiological Protection (ICRP) Publication 103 provided a detailed explanation of the purpose and use of effective dose and equivalent dose to individual organs and tissues. Effective dose has proven to be a valuable and robust quantity for use in the implementation of protection principles. However, questions have arisen regarding practical applications, and a Task Group has been set up to consider issues of concern. This paper focusses on two key proposals developed by the Task Group that are under consideration by ICRP: (1) confusion will be avoided if equivalent dose is no longer used as a protection quantity, but regarded as an intermediate step in the calculation of effective dose. It would be more appropriate for limits for the avoidance of deterministic effects to the hands and feet, lens of the eye, and skin, to be set in terms of the quantity, absorbed dose (Gy) rather than equivalent dose (Sv). (2) Effective dose is in widespread use in medical practice as a measure of risk, thereby going beyond its intended purpose. While doses incurred at low levels of exposure may be measured or assessed with reasonable reliability, health effects have not been demonstrated reliably at such levels but are inferred. However, bearing in mind the uncertainties associated with risk projection to low doses or low dose rates, it may be considered reasonable to use effective dose as a rough indicator of possible risk, with the additional consideration of variation in risk with age, sex and population group.

  6. Absorbed fractions for electrons in ellipsoidal volumes.

    PubMed

    Amato, E; Lizio, D; Baldari, S

    2011-01-21

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as (90)Y and to (131)I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  7. Absorbed fractions for electrons in ellipsoidal volumes

    NASA Astrophysics Data System (ADS)

    Amato, E.; Lizio, D.; Baldari, S.

    2011-01-01

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  8. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  9. Liquid Hydrogen Absorber for MICE

    SciTech Connect

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing

    2010-05-30

    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  10. Electrochemically regenerable carbon dioxide absorber

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.; Heppner, D. B.

    1979-01-01

    Preliminary designs were generated for two electrochemically regenerable carbon dioxide absorber concepts. Initially, an electrochemically regenerable absorption bed concept was designed. This concept incorporated the required electrochemical regeneration components in the absorber design, permitting the absorbent to be regenerated within the absorption bed. This hardware was identified as the electrochemical absorber hardware. The second hardware concept separated the functional components of the regeneration and absorption process. This design approach minimized the extravehicular activity component volume by eliminating regeneration hardware components within the absorber. The electrochemical absorber hardware was extensively characterized for major operating parameters such as inlet carbon dioxide partial pressure, process air flow rate, operational pressure, inlet relative humidity, regeneration current density and absorption/regeneration cycle endurance testing.

  11. Plants absorb heavy metals

    SciTech Connect

    Parry, J.

    1995-02-01

    Decontamination of heavy metals-polluted soils remains one of the most intractable problems of cleanup technology. Currently available techniques include extraction of the metals by physical and chemical means, such as acid leaching and electroosmosis, or immobilization by vitrification. There are presently no techniques for cleanup which are low cost and retain soil fertility after metals removal. But a solution to the problem could be on the horizon. A small but growing number of plants native to metalliferous soils are known to be capable of accumulating extremely high concentrations of metals in their aboveground portions. These hyperaccumulators, as they are called, contain up to 1,000 times larger metal concentrations in their aboveground parts than normal species. Their distribution is global, including many different families of flowering plants of varying growth forms, from herbaceous plants to trees. Hyperaccumulators absorb metals they do not need for their own nutrition. The metals are accumulated in the leaf and stem vacuoles, and to a lesser extent in the roots.

  12. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  13. Hydraulic shock absorber

    SciTech Connect

    Tanaka, T.

    1987-03-03

    This patent describes a hydraulic shock absorber including a piston reciprocating in a cylinder, a piston upper chamber and a piston lower chamber which are oil-tightly separated by the piston, piston ports formed through the piston in a circle for communicating the piston upper chamber with the piston lower chamber, and return ports formed outside of the piston ports in a circle for communicating the piston upper chamber with the piston lower chamber. It also includes a sheet ring-like non-return valve provided above the piston and fitted to a piston rod, valve holes formed through the non-return valve in opposed relation with the piston ports. A ring-like non-return valve stopper fixed to the piston rod on an upper side of the non-return valve with a small spaced defined between the non-return valve and the non-return valve stopper, and a spring is interposed between the non-return valve and the non-return valve stopper for normally urging the non-return valve to an upper surface of the piston. Movement of the piston to the piston upper chamber allows oil to flow from the piston upper chamber through the piston ports to the piston lower chamber, while the return ports are closed by the non-return valve to generate a vibration damping force by resistance upon pass of the oil through the piston parts. The improvement described here comprises a groove formed in an upper surface of the piston facing the non-return valve and aligned with the valve holes, the groove being in the circle where the piston ports lie and being in communication with the piston ports.

  14. Metal-shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P.

    1971-01-01

    Device, consisting of tongue of thin aluminum alloy strip, pull tab, slotted steel plate which serves as cutter, and steel buckle, absorbs mechanical energy when its ends are subjected to tensile loading. Device is applicable as auxiliary shock absorbing anchor for automobile and airplane safety belts.

  15. The broadband dynamic vibration absorber

    NASA Astrophysics Data System (ADS)

    Hunt, J. B.; Nissen, J.-C.

    1982-08-01

    The limited effectiveness of the linear passive dynamic vibration absorber is described. This is followed by an analysis producing the response of a primary system when a non-linear softening Belleville spring is used in the absorber. It is shown that the suppression bandwidth can be doubled by this means.

  16. In vitro RABiT measurement of dose rate effects on radiation induction of micronuclei in human peripheral blood lymphocytes.

    PubMed

    Bertucci, Antonella; Smilenov, Lubomir B; Turner, Helen C; Amundson, Sally A; Brenner, David J

    2016-03-01

    Developing new methods for radiation biodosimetry has been identified as a high-priority need in case of a radiological accident or nuclear terrorist attacks. A large-scale radiological incident would result in an immediate critical need to assess the radiation doses received by thousands of individuals. Casualties will be exposed to different doses and dose rates due to their geographical position and sheltering conditions, and dose rate is one of the principal factors that determine the biological consequences of a given absorbed dose. In these scenarios, high-throughput platforms are required to identify the biological dose in a large number of exposed individuals for clinical monitoring and medical treatment. The Rapid Automated Biodosimetry Tool (RABiT) is designed to be completely automated from the input of blood sample into the machine to the output of a dose estimate. The primary goal of this paper was to quantify the dose rate effects for RABiT-measured micronuclei in vitro in human lymphocytes. Blood samples from healthy volunteers were exposed in vitro to different doses of X-rays to acute and protracted doses over a period up to 24 h. The acute dose was delivered at ~1.03 Gy/min and the low dose rate exposure at ~0.31 Gy/min. The results showed that the yield of micronuclei decreases with decreasing dose rate starting at 2 Gy, whereas response was indistinguishable from that of acute exposure in the low dose region, up to 0.5 Gy. The results showed a linear-quadratic dose-response relationship for the occurrence of micronuclei for the acute exposure and a linear dose-response relationship for the low dose rate exposure. PMID:26791381

  17. In vitro RABiT measurement of dose rate effects on radiation induction of micronuclei in human peripheral blood lymphocytes

    PubMed Central

    Bertucci, Antonella; Smilenov, Lubomir B.; Turner, Helen C.; Amundson, Sally A.; Brenner, David J.

    2016-01-01

    Developing new methods for radiation biodosimetry has been identified as a high priority need in case of a radiological accident or nuclear terrorist attacks. A large-scale radiological incident would result in an immediate critical need to assess the radiation doses received by thousands of individuals. Casualties will be exposed to different doses and dose-rates due to their geographical position and sheltering conditions, and dose-rate is one of the principal factors that determine the biological consequences of a given absorbed dose. In these scenarios high-throughput platforms are required to identify the biological dose in a large number of exposed individuals for clinical monitoring and medical treatment. The RABiT (Rapid Automated Biodosimetry Tool) is designed to be completely automated from the input of blood sample into the machine to the output of a dose estimate. The primary goal of this paper was to quantify the dose-rate effects for RABiT-measured micronuclei in vitro in human lymphocytes. Blood samples from healthy volunteers were exposed in vitro to different doses of X-rays to acute and protracted doses over a period up to 24 hours. The acute dose (ADR) was delivered at ∼1.03Gy/min and the low dose rate (LDR) exposure at ∼0.31Gy/min. The results showed that the yield of micronuclei decreases with decreasing dose-rate starting at 2Gy, whereas response was indistinguishable from that of acute exposure in the low dose region, up to 0.5Gy. The results showed a linear-quadratic dose-response relationship for the occurrence of micronuclei for the acute exposure and a linear dose-response relationship for the low dose-rate exposure. PMID:26791381

  18. Absorbed radiation by various tissues during simulated endodontic radiography

    SciTech Connect

    Torabinejad, M.; Danforth, R.; Andrews, K.; Chan, C.

    1989-06-01

    The amount of absorbed radiation by various organs was determined by placing lithium fluoride thermoluminescent chip dosimeters at selected anatomical sites in and on a human-like X-ray phantom and exposing them to radiation at 70- and 90-kV X-ray peaks during simulated endodontic radiography. The mean exposure dose was determined for each anatomical site. The results show that endodontic X-ray doses received by patients are low when compared with other radiographic procedures.

  19. Evaluation of the peripheral dose in stereotactic radiotherapy and radiosurgery treatments

    SciTech Connect

    Di Betta, Erika; Fariselli, Laura; Bergantin, Achille; Locatelli, Federica; Del Vecchio, Antonella; Broggi, Sara; Fumagalli, Maria Luisa

    2010-07-15

    Purpose: The main purpose of this work was to compare peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using different devices. These data were used to estimate the risk of stochastic effects. Methods: Treatment plans were created for an anthropomorphic phantom and delivered using a LINAC with stereotactic cones and a multileaf collimator, a CyberKnife system (before and after a supplemental shielding was applied), a TomoTherapy system, and a Gamma Knife unit. For each treatment, 5 Gy were prescribed to the target. Measurements were performed with thermoluminescent dosimeters inserted roughly in the position of the thyroid, sternum, upper lung, lower lung, and gonads. Results: Mean doses ranged from of 4.1 (Gamma Knife) to 62.8 mGy (LINAC with cones) in the thyroid, from 2.3 (TomoTherapy) to 30 mGy (preshielding CyberKnife) in the sternum, from 1.7 (TomoTherapy) to 20 mGy (preshielding CyberKnife) in the upper part of the lungs, from 0.98 (Gamma Knife) to 15 mGy (preshielding CyberKnife) in the lower part of the lungs, and between 0.3 (Gamma Knife) and 10 mGy (preshielding CyberKnife) in the gonads. Conclusions: The peripheral dose absorbed in the sites of interest with a 5 Gy fraction is low. Although the risk of adverse side effects calculated for 20 Gy delivered in 5 Gy fractions is negligible, in the interest of optimum patient radioprotection, further studies are needed to determine the weight of each contributor to the peripheral dose.

  20. Absorbent product to absorb fluids. [for collection of human wastes

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  1. Evaluation of the medical exposure doses regarding dental examinations with different X-ray instruments

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Chi; Chuang, Keh-Shih; Yu, Cheng-Ching; Chao, Jiunn-Hsing; Hsu, Fang-Yuh

    2015-11-01

    Modern dental X-ray examination that consists of traditional form, panorama, and cone-beamed 3D technologies is one of the most frequent diagnostic applications nowadays. This study used the Rando Phantom and thermoluminescence dosimeters (TLD) to measure the absorbed doses of radiosensitive organs recommended by International Commission on Radiological Protection (ICRP), and whole body effective doses which were delivered due to dental X-ray examination performed with different types of X-ray instrument. Besides, enamel samples which performed reading with Electronic Paramagnetic Resonance (EPR) procedure were also used to estimate the tooth doses. EPR is a dose reconstruction method of measuring free radicals induced by radiation exposure to the calcified tissue (mainly in the tooth enamel or bone) to evaluate the accepted high dose. The tooth doses estimated by TLD and EPR methods were compared. Relationships between the tooth doses and effective doses by dental X-ray examinations with different types of X-ray equipment were investigated in this work.

  2. Tomotherapy dose distribution verification using MAGIC-f polymer gel dosimetry

    SciTech Connect

    Pavoni, J. F.; Pike, T. L.; Snow, J.; DeWerd, L.; Baffa, O.

    2012-05-15

    Purpose: This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. Methods: A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treatment was delivered by a TomoTherapy equipment. Dose distribution was evaluated by the R2 distribution measured in magnetic resonance imaging. Results: A high similarity was found by overlapping of isodoses of the dose distribution measured with the gel and expected by the treatment planning system (TPS). Another analysis was done by comparing the relative absorbed dose profiles in the measured and in the expected dose distributions extracted along indicated lines of the volume and the results were also in agreement. The gamma index analysis was also applied to the data and a high pass rate was achieved (88.4% for analysis using 3%/3 mm and of 96.5% using 4%/4 mm). The real three-dimensional analysis compared the dose-volume histograms measured for the planning volumes and expected by the treatment planning, being the results also in good agreement by the overlapping of the curves. Conclusions: These results show that MAGIC-f gel is a promise for tridimensional dose distribution measurements.

  3. An absolute dose determination of helical tomotherapy accelerator, TomoTherapy High-Art II

    SciTech Connect

    Bailat, Claude J.; Buchillier, Thierry; Pachoud, Marc; Moeckli, Raphaeel; Bochud, Francois O.

    2009-09-15

    Purpose: A helical tomotherapy accelerator presents a dosimetric challenge because, to this day, there is no internationally accepted protocol for the determination of the absolute dose. Because of this reality, we investigated the different alternatives for characterizing and measuring the absolute dose of such an accelerator. We tested several dosimetric techniques with various metrological traceabilities as well as using a number of phantoms in static and helical modes. Methods: Firstly, the relationship between the reading of ionization chambers and the absorbed dose is dependent on the beam quality value of the photon beam. For high energy photons, the beam quality is specified by the tissue phantom ratio (TPR{sub 20,10}) and it is therefore necessary to know the TPR{sub 20,10} to calculate the dose delivered by a given accelerator. This parameter is obtained through the ratio of the absorbed dose at 20 and 10 cm depths in water and was measured in the particular conditions of the tomotherapy accelerator. Afterward, measurements were performed using the ionization chamber (model A1SL) delivered as a reference instrument by the vendor. This chamber is traceable in absorbed dose to water in a Co-60 beam to a water calorimeter of the American metrology institute (NIST). Similarly, in Switzerland, each radiotherapy department is directly traceable to the Swiss metrology institute (METAS) in absorbed dose to water based on a water calorimeter. For our research, this traceability was obtained by using an ionization chamber traceable to METAS (model NE 2611A), which is the secondary standard of our institute. Furthermore, in order to have another fully independent measurement method, we determined the dose using alanine dosimeters provided by and traceable to the British metrology institute (NPL); they are calibrated in absorbed dose to water using a graphite calorimeter. And finally, we wanted to take into account the type of chamber routinely used in clinical

  4. Self-Regulating Shock Absorber

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1995-01-01

    Mechanical shock absorber keeps frictional damping force within tolerable limit. Its damping force does not increase with coefficient of friction between energy-absorbing components; rather, frictional damping force varies only slightly. Relatively insensitive to manufacturing variations and environmental conditions altering friction. Does not exhibit high breakaway friction and consequent sharp increase followed by sharp decrease in damping force at beginning of stroking. Damping force in absorber does not vary appreciably with speed of stroking. In addition, not vulnerable to leakage of hydraulic fluid.

  5. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, William H.

    1984-01-01

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system.

  6. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, W.H.

    1984-10-16

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system. 9 figs.

  7. Comparison of the targeting characteristics of various radioimmunoconjugates for radioimmunotherapy of neuroblastoma: dosimetry calculations incorporating cross-organ beta doses.

    PubMed

    Ugur, O; Kostakoglu, L; Hui, E T; Fisher, D R; Garmestani, K; Gansow, O A; Cheung, N K; Larson, S M

    1996-01-01

    To optimize the efficacy of radioimmunotherapy (RIT), the ideal antibody-radioisotope combinations should be used to deliver the highest tumor and the lowest normal tissue doses. In a mouse model, tumor and critical organ-absorbed doses delivered by different radioimmunoconjugates were calculated and compared. We used a Medical Internal Radiation Dosimetry (MIRD)-style mouse dosimetry model that incorporates cross-organ beta doses to make refined estimates of the radiation absorbed dose to tissues. Biodistribution data from neuroblastoma xenografted nude mice were used to estimate tumor, organ and bone marrow absorbed dose values for 90Y-3F8, 131I-3F8 and 131I-F(ab')2 fragments. Immunoreactive fractions of the radiolabeled antibodies were comparable. Although tumor uptake of the radioiodinated and radiometal labeled 3F8 was much higher than that of the radioiodinated F(ab')2 fragments (maximum percent injected dose per gram values were 39.4, 33.2 and 20.1 for 131I-3F8, 90Y-3F8 and 131I-F(ab')2, respectively), tumor to nontumor ratios were higher for radioiodinated fragments (with the exception of tumor to kidney ratio). For the minimum tumor dose necessary for complete ablation, the bone marrow received 195, 278 and 401 cGy for 131I-F(ab')2, 131I-3F8 and 90Y-3F8, respectively. Tumor doses were 50.1, 232 and 992 cGy/MBq for 131I-F(ab')2, 131I-3F8 and 90Y-3F8, respectively. Tumor to bone marrow dose, which is defined as the therapeutic index, was 21.5, 14.7 and 10.4 for 131I-F(ab')2, 131I-3F8 and 90Y-3F8. 131I-F(ab')2 fragments produced the highest therapeutic index but also the lowest tumor dose for radioimmunotherapy. Radiometal conjugated IgG produced the highest tumor dose but also the lowest therapeutic index.

  8. Myeloablative 131I-Tositumomab Radioimmunotherapy in Treating Non-Hodgkin’s Lymphoma: Comparison of Dosimetry Based on Whole-Body Retention and Dose to Critical Organ Receiving the Highest Dose

    SciTech Connect

    Rajendran, Joseph G.; Gopal, Ajay K.; Fisher, Darrell R.; Durack, L. D.; Gooley, Ted; Press, Oliver W.

    2008-05-01

    Objectives: Myeloablative radioimmunotherapy (RIT) using 131I tositumomab (anti-CD 20) monoclonal antibodies is an effective new therapy for B-cell non-Hodgkins lymphoma (NHL). The goal of this work is to determine optimum methods to deliver maximal myeloablative radioactivity without exceeding the radiation tolerance of critical normal organs such as liver and lungs, and avoiding serious toxicity. Methods: We reviewed dosimetry records for 100 consecutive patients who underwent biodistribution and dosimetry after a test infusion of 131I- tositumomab. Serial gamma camera images were used to determine organ and tissue activities over time and to calculate radiation-absorbed doses. Volumes of critical normal organs were determined from CT scans to adjust the dose estimates for the individual patient. These dose estimates helped us determine an appropriate therapy based on projected dose to the critical normal organ receiving a maximum tolerable radiation dose. We compared our method of organ-specific dosimetry for treatment planning with the standard clinical approaches using a whole-body dose-assessment method by assessing the difference in projected amounts of radiation-absorbed doses, as well as the ratios of projected amounts, that would be prescribed for therapy by each of these two strategies. Results: The mean organ doses (mGy/MBq) estimated by both methods were (1) Whole body method: liver = 0.33 and lungs = 0.33; and (2) Organ-specific method: liver 1.52 and lungs 1.72 (p = .0001). The median difference between the radiation-absorbed dose estimates was 3.40 (range of 1.37 to 7.96) for the lungs, 3.05 (range of 1.04 to 6.20) for the liver, and –0.05 for whole body (range of –0.18 to 0.16). The median ratio (OS divided by WB method) of radiation-absorbed dose estimates was 5.12 (range of 2.33 to 10.01) for the lungs, 4.14 (range of 2.16 to 6.67) for the liver, and 0.94 (range of 0.79 to 1.22) for whole body. There was significant difference between the

  9. Carbon Absorber Retrofit Equipment (CARE)

    SciTech Connect

    Klein, Eric

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  10. Mushroom plasmonic metamaterial infrared absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  11. Additive manufacturing of RF absorbers

    NASA Astrophysics Data System (ADS)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  12. Mushroom plasmonic metamaterial infrared absorbers

    SciTech Connect

    Ogawa, Shinpei Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  13. Nonventing, Regenerable, Lightweight Heat Absorber

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Chen, Weibo

    2008-01-01

    A lightweight, regenerable heat absorber (RHA), developed for rejecting metabolic heat from a space suit, may also be useful on Earth for short-term cooling of heavy protective garments. Unlike prior space-suit-cooling systems, a system that includes this RHA does not vent water. The closed system contains water reservoirs, tubes through which water is circulated to absorb heat, an evaporator, and an absorber/radiator. The radiator includes a solution of LiCl contained in a porous material in titanium tubes. The evaporator cools water that circulates through a liquid-cooled garment. Water vapor produced in the evaporator enters the radiator tubes where it is absorbed into the LiCl solution, releasing heat. Much of the heat of absorption is rejected to the environment via the radiator. After use, the RHA is regenerated by heating it to a temperature of 100 C for about 2 hours to drive the absorbed water back to the evaporator. A system including a prototype of the RHA was found to be capable of maintaining a temperature of 20 C while removing heat at a rate of 200 W for 6 hours.

  14. Effects of Proton Radiation Dose, Dose Rate and Dose Fractionation on Hematopoietic Cells in Mice

    PubMed Central

    Ware, J. H.; Sanzari, J.; Avery, S.; Sayers, C.; Krigsfeld, G.; Nuth, M.; Wan, X. S.; Rusek, A.; Kennedy, A. R.

    2012-01-01

    The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05–0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons. PMID:20726731

  15. Effects of proton radiation dose, dose rate and dose fractionation on hematopoietic cells in mice

    SciTech Connect

    Ware, J.H.; Rusek, A.; Sanzari, J.; Avery, S.; Sayers, C.; Krigsfeld, G.; Nuth, M.; Wan, X.S.; Kennedy, A.R.

    2010-09-01

    The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05-0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons.

  16. Evaluation of Drug Concentrations Delivered by Microiontophoresis.

    PubMed

    Kirkpatrick, Douglas C; Wightman, R Mark

    2016-06-21

    Microiontophoresis uses an electric current to eject a drug solution from a glass capillary and is often utilized for targeted delivery in neurochemical investigations. The amount of drug ejected, and its effective concentration at the tip, has historically been difficult to determine, which has precluded its use in quantitative studies. To address this, a method called controlled iontophoresis was developed which employs a carbon-fiber microelectrode incorporated into a multibarreled iontophoretic probe to detect the ejection of electroactive species. Here, we evaluate the accuracy of this method. To do this, we eject different concentrations of quinpirole, a D2 receptor agonist, into a brain slice containing the dorsal striatum, a brain region with a high density of dopamine terminals. Local electrical stimulation was used to evoke dopamine release, and inhibitory actions of quinpirole on this release were examined. The amount of drug ejected was estimated by detection of a coejected electrochemical marker. Dose response curves generated in this manner were compared to curves generated by conventional perfusion of quinpirole through the slice. We find several experimental conditions must be optimized for accurate results. First, selection of a marker with an identical charge was necessary to mimic the ejection of the cationic agonist. Next, evoked responses were more precise following longer periods between the end of the ejection and stimulation. Lastly, the accuracy of concentration evaluations was improved by longer ejections. Incorporation of these factors into existing protocols allows for greater certainty of concentrations delivered by controlled iontophoresis. PMID:27212615

  17. 131I-tositumomab myeloablative radioimmunotherapy for non-Hodgkin’s lymphoma: radiation dose to the testes

    SciTech Connect

    Hattori, Naoya; Gopal, Ajay K.; Shields, Andrew T.; Fisher, Darrell R.; Gooley, Ted; Pagel, John M.; Press, Oliver W.; Rajendran, Joseph G.

    2012-12-01

    Purpose: To investigate radiation doses to the testes delivered by a radiolabeled anti-CD20 antibody and its effects on male sex hormone levels. Materials and methods: Testicular uptake and retention of 131I-tositumomab were measured, and testicular absorbed doses were calculated for 67 male patients (54+/-11 years of age) with non-Hodgkin's lymphoma who had undergone myeloablative radioimmunotherapy (RIT) using 131I-tositumomab. Time-activity curves for the major organs, testes, and whole body were generated from planar imaging studies. In a subset of patients, male sex hormones were measured before and 1 year after the therapy. Results: The absorbed dose to the testes showed considerable variability (range=4.4-70.2 Gy). Pretherapy levels of total testosterone were below the lower limit of the reference range, and post-therapy evaluation demonstrated further reduction [4.6+/-1.8 nmol/l (pre-RIT) vs. 3.8+/-2.9 nmol/l (post-RIT), P<0.05]. Patients receiving higher radiation doses to the testes (>=25 Gy) showed a greater reduction [4.7+/-1.6 nmol/l (pre-RIT) vs. 3.3+/-2.7 nmol/l (post-RIT), P<0.05] compared with patients receiving lower doses (<25 Gy), who showed no significant change in total testosterone levels. Conclusion: The testicular radiation absorbed dose varied highly among individual patients. Finally, patients receiving higher doses to the testes were more likely to show post-RIT suppression of testosterone levels.

  18. Novel Glucagon-Like Peptide-1 Analog Delivered Orally Reduces Postprandial Glucose Excursions in Porcine and Canine Models

    PubMed Central

    Eldor, Roy; Kidron, Miriam; Greenberg-Shushlav, Yael; Arbit, Ehud

    2010-01-01

    Background Glucagon-like peptide-1 (GLP-1) and its analogs are associated with a gamut of physiological processes, including induction of insulin release, support of normoglycemia, β-cell function preservation, improved lipid profiles, and increased insulin sensitivity. Thus, GLP-1 harbors significant therapeutic potential for regulating type 2 diabetes mellitus, where its physiological impact is markedly impaired. To date, GLP-1 analogs are only available as injectable dosage forms, and its oral delivery is expected to provide physiological portal/peripheral concentration ratios while fostering patient compliance and adherence. Methods Healthy, fasting, enterically cannulated pigs and beagle canines were administered a single dose of the exenatide-based ORMD-0901 formulation 30 min before oral glucose challenges. Blood samples were collected every 15 min for evaluation of ORMD-0901 safety and efficacy in regulating postchallenge glucose excursions. Results Enterically delivered ORMD-0901 was well tolerated by all animals. ORMD-0901 formulations RG3 and AG2 led to reduced glucose excursions in pigs when delivered prior to a 5 g/kg glucose challenge, where area under the curve (AUC)0–120 values were up to 43% lower than in control sessions. All canines challenged with a glucose load with no prior exposure to exenatide, demonstrated higher AUC0–150 values than in their exenatide-treated sessions. Subcutaneous exenatide delivery amounted to a 51% reduction in mean glucose AUC0–150, while formulations AG4 and AG3 prompted 43% and 29% reductions, respectively. Conclusions When delivered enterically, GLP-1 (ORMD-0901) is absorbed from the canine and porcine gastrointestinal tracts and retains its biological activity. Further development of this drug class in an oral dosage form is expected to enhance diabetes control and patient compliance. PMID:21129350

  19. Delivering Science from Big Data

    NASA Astrophysics Data System (ADS)

    Quinn, Peter Joseph

    2015-08-01

    The SKA will be capable of producing a stream of science data products that are Exa-scale in terms